In vitro and in vivo evaluation of novel cinnamyl sulfonamide hydroxamate derivative against colon adenocarcinoma

Article abstract of DOI:10.1016/j.cbi.2015.03.015

The potential of cinnamic acid as an anti-inflammatory and anti-cancer agent has been studied previously. In our investigation, novel bio-isosters of cinnamyl sulfonamide hydroxamate were synthesized, characterized and confirmed for their structure and ev

Full text of DOI:10.1016/j.cbi.2015.03.015

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Chemico-Biological Interactions xxx (2015) xxx–xxx
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Contents lists available at ScienceDirect
Chemico-Biological Interactions
journal homepage: www.elsevier.com/locate/chembioint
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In vitro and in vivo evaluation of novel cinnamyl sulfonamide
hydroxamate derivative against colon adenocarcinoma
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Neetinkumar D. Reddy a, M.H. Shoja a, B.S. Jayashree b, Pawan G. Nayak a, Nitesh Kumar a,
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V. Ganga Prasad a, K. Sreedhara R. Pai a, C. Mallikarjuna Rao a,
⇑
a Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka, India
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b Department of Pharmaceutical Chemistry, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka, India
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a r t i c l e i n f o
a b s t r a c t
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Article history:
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The potential of cinnamic acid as an anti-inflammatory and anti-cancer agent has been studied pre-
viously. In our investigation, novel bio-isosters of cinnamyl sulfonamide hydroxamate were synthesized,
characterized and confirmed for their structure and evaluated for cytotoxicity. Three NCEs namely, NMJ-
1, -2 and -3 showed cell-growth inhibition in 6 human cancer cell lines with IC50 at the range of
Received 26 August 2014
Received in revised form 3 February 2015
Accepted 18 March 2015
Available online xxxx
3.3 0.15–44.9 2.6
of HDAC enzyme. Thus, the effectiveness of these molecules was determined by whole cell HDAC assay
in HCT 116 cell line. NMJ-2 (0.41 0.01 M) exhibited better enzyme inhibition (IC50) compared to SAHA
lM. The hydroxamate derivatives of cinnamyl sulfonamide are reported inhibitors
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Keywords:
l
Colon cancer
Cinnamic acid
HDAC
Apoptosis
Caspase 3/7
(2.63 0.07). In order to evaluate induction of apoptosis by treatment, Hoechst 33342 and AO/EB nuclear
staining methods were used. Further, cell cycle analysis, Annexin V binding and caspase 3/7 activation
assays were performed by flow cytometry where NMJ-2 significantly arrested the cell cycle at G2/M
phase, increased Annexin V binding to the cell surface and activation of caspase-3/7. Bax/Bcl-2 ratio
was observed by Western blot and showed an increase with NMJ-2 treatment. This was comparable to
standard SAHA. The acute toxicity study (OECD-425) showed that NMJ-2 was safe up to 2000 mg/kg in
rats. 1,2-Dimethyl hydrazine (DMH) was used to produce experimental colon adenocarcinoma in
Wistar rats. 5-FU and NMJ-2 (100 mg/kg p.o. and 10 mg/kg i.p. once daily for 21 days, respectively) were
administered to the respective groups. Both treatments significantly reduced ACFs, adenocarcinoma
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1,2-Dimethyl hydrazine (DMH)
count, TNF-a, IL-6, nitrite and nitrate levels in colonic tissue. Our findings indicate that NMJ-2 has potent
anti-cancer activity against colon cancer, by acting through HDAC enzyme inhibition and activation of
intrinsic mitochondrial apoptotic pathway, with additional anti-inflammatory activity.
Ó 2015 Published by Elsevier Ireland Ltd.
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1. Introduction
is now a common malignancy in various parts of the world.
Numerous cell-signaling pathways have pivotal roles to play in
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Cancer has reached epidemic proportions globally and accounts
for 12 million cases worldwide and 7.9 million deaths [1]. It
accounts for 13% of all deaths each year with the most common
being lung, stomach, colorectal, liver and breast cancer [2,3]. It is
found that generally cancer risk rises with old age [4]. Colon cancer
the proliferation of malignant cells. The search for newer avenues
in the treatment of cancer has led research into the elucidation of
signaling pathways. The complexity associated with this disease
has led scientists to identify targets for the different phases of
tumor formation via cell differentiation, proliferation, cell cycle
Abbreviations: ACF, aberrant crypt foci; AO/EB, acridine orange/ethidium bromide; CPCSEA, Committee for the Purpose of Control and Supervision of Experiments on
Animals; CMC, carboxymethylcellulose; DMEM, Dulbecco’s minimum essential media; DMSO, dimethyl sulfoxide; DMH, 1,2-dimethyl hydrazine; FBS, fetal bovine serum; 5-
FU, 5-fluorouracil; HDAC, histone deacetylase; HDACi, HDAC inhibitors; HepG2, human liver adenocarcinoma; HCT 116, human colon adenocarcinoma; IL-6, interleukin-6;
i.p., intra-peritoneal; MCF-7, human breast (ER+) adenocarcinoma; MDA-MB-231, human breast (ERÀ) adenocarcinoma; MTT,
3-(4,5-dimethylthiazol-2-yl)-2,5-
diphenyltetrazolium bromide; NCE, new chemical entity; NO, nitric oxide; OECD, Organization for Economic Co-operation and Development; PC3, human prostate
adenocarcinoma; PBS, phosphate buffer saline; PI, propidium iodide; p.o., per oral; S.E.M., standard error of mean; SAHA, suberoyl anilide hydroxamic acid; SH-SY5Y, human
neuroblastoma; TNF-
a
, tumor necrosis factor-
a
; Vero, African green monkey kidney epithelial cell line.
⇑
Corresponding author. Tel.: +91 0820 2922482 (O).
E-mail addresses: mallikin123@gmail.com, mallik.rao@manipal.edu (C. Mallikarjuna Rao).
http://dx.doi.org/10.1016/j.cbi.2015.03.015
0009-2797/Ó 2015 Published by Elsevier Ireland Ltd.
Please cite this article in press as: N.D. Reddy et al., In vitro and in vivo evaluation of novel cinnamyl sulfonamide hydroxamate derivative against colon
adenocarcinoma, Chemico-Biological Interactions (2015), http://dx.doi.org/10.1016/j.cbi.2015.03.015

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check point defect, migration and cell survival through onco-gene
activation etc. [5].
2.2. Equipment for synthesis and characterization of synthesized
compounds
Cancer is caused by abnormal epigenetic modifications in addi-
tion to multiple genetic mutations. Certain validated targets such as
tyrosine kinase, farnesyl transferase, histone deacetylase (HDAC),
aromatase, etc. play a central role in the development of target
specific anticancer agents. Histone deacetylase (HDAC) enzyme
overexpression, linked to many cancer types, is responsible
for tumor suppressor gene silencing and activation of proto-
oncogenes. The altered expression of HDACs play a direct or indirect
role in tumor development [6]. HDAC inhibitors (HDACi), a new
class of anti-cancer agents, play a crucial role in epigenetic mod-
ification, activation of tumor suppressor genes, cell cycle regulation
and apoptosis induction in cancer cells. Several HDACi are under
pre-clinical or clinical trials. The limitations of these molecules
include thrombocytopenia, cardiac problems and poor efficacy
against solid tumors etc. [7]. Thus, there is a scope to improve their
safety and efficacy.
From time immemorial, use of Tolu balsam as an anti-in-
flammatory and anti-cancer agent has been well documented
owing to the presence of esters of benzoic and cinnamic acid [8].
In recent studies, cinnamic acid derivatives showed anti-cancer
activity via HDAC enzyme inhibition [9]. Based on these findings,
we made modifications in the cinnamic acid moiety to obtain cin-
namyl sulfonamide hydroxamate derivatives. The design evolved
around the concept of bio-isosterism and was used as a tool in lead
modification [10]; where, the benzene ring of the known available
HDACi such as SAHA/PDX101, was conveniently replaced by elec-
tronically equivalent ring counterpart such as thiophene. The bio-
logical activities of these newly formed NCEs were compared with
their phenyl counterparts. Hence, the aim of the present study was
to synthesize novel cinnamyl sulfonamide-hydroxamate deriva-
tives and evaluate them for anti-cancer efficacy by in vitro and
in vivo colon adenocarcinoma models.
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Melting point of the synthesized test compounds were deter-
mined using capillary melting point apparatus (Toshniwal
Systems and Instruments Pvt. Ltd., Chennai, TN, India). The reac-
tion status was checked by TLC on pre-coated silica gel plates
(Merck # 60F254). Spots were visualized under both long and short
UV range using UV lamp (366 or 254 nm) and iodine chamber. The
Rf values for the synthesized test compounds were determined
using chloroform: methanol (9:1) solvent system. Further, the test
compounds were purified by silica gel column chromatography.
The IR spectra were recorded using IR spectrometer (Model FTIR-
8300, Shimadzu Co., Kyoto, Japan) using KBr pellets. 1H and 13C
NMR were recorded at 400 MHz (Model Ascend 400, Bruker
Biosciences Corporation, Billerica, MA, USA) using DMSO (D6) as
solvent. Mass spectra were recorded using LC-MS (ESI) (Model
LCMS-2010A, Shimadzu Co., Kyoto, Japan). CHN-S elementary
analyses were done by Vario EL Ver III CHNS analyzer from
Elemental Analysensysteme, GmbH, Germany. NMR, Mass spectra
and CHN-S analysis fully supported the final structures of the test
compounds. Purity of the test compounds was established on RP-
HPLC unit (Shimadzu Co., Kyoto, Japan) with a PDA detector
(254 nm) using a Hichrom C18 (250 Â 4.6 mm i.d., 5
lm) column
with acetonitrile as solvent in pump A and aqueous solution of
0.1% formic acid (pH 6.0) as solvent in pump B by gradient elution.
Flow rate of 1.0 ml/min was maintained with a run time of 35 min
and column temperature of 30 °C.
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2.3. Cell culture and maintenance
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All the cell lines (HCT 116, MCF-7, MDA-MB-231, HepG2, SH-
SY5Y and Vero) were procured from the National Centre for Cell
Science, Pune, MH, India. The cells were maintained in high glucose
DMEM medium with 10% FBS and 1% penicillin–streptomycin, at
37 °C in a CO2 incubator (NU-5510E, NuAire Inc., Plymouth, MN,
USA). Trypan blue dye exclusion method was used to check viabil-
ity of cells and >95% viable cells in culture were used through the
experiments. The MTT cell viability assay was performed in all 6
cancer cell lines and rest of the in vitro studies were done in HCT
116 colon cancer cell line. Three independent experiments in tripli-
cates were done for the all in vitro procedures (n = 3).
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2. Materials and methods
2.1. Common chemicals and reagents
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Starting materials of synthetic grade were obtained from
(Sigma–Aldrich Co. LLC, St. Louis, MO, USA; Merck KGaA,
Darmstadt, Germany; Spectrochem Pvt. Ltd., Mumbai, MH, India;
TCI Co. Ltd., Tokyo, Japan). Dulbecco’s modified Eagle’s medium
(DMEM), phosphatase inhibitor cocktail, protease inhibitor cock-
tail, propidium iodide (# P4170), SAHA (# SML0061), Boc-
Lys(Ac)-AMC substrate (# SCP0168) and Nonidet-P 40 (NP-40),
Griess’ reagent (# 03553), vanadium (III) chloride (# 208272) were
obtained from Sigma–Aldrich Co. LLC, MO, USA; fetal bovine serum
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2.4. Animals, dose administration and treatments
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Wistar rats (120–150 g) were used in the study from well-main-
tained in-house bred, of the Central Animal Research Facility,
Manipal University, Manipal, Karnataka, India. All animal experi-
ments were conducted according CPCSEA guidelines, Government
of India and after obtaining the experimental protocol approval
(No. IAEC/KMC/19/2012) from the Institutional Animal Ethics
Committee (Animal Use and Care Committee). Animals were accli-
matized in polypropylene cages in experimental room and given
standard food pellet rodent diet and water ad libitum and kept
under controlled humidity conditions 45–55%, temperature
25 2 °C, ventilation 10–12 exchanges/h and 12:12 h light and
dark cycle. 5-FU was used as standard drug at a dose of 10 mg/
kg, i.p. injection which is one twenty fifth (1/25th) of human dose,
converted to the rat dose (Paget and Barnes, 1964). NMJ-2 dose
was selected based on acute toxicity study limit test (up to
2000 mg/kg). One twentieth (1/20th) of the maximum tested safe
dose, i.e. 100 mg/kg was selected for anti-cancer study and admi-
nistered for a period of 21 days. All other test compounds were
prepared as suspensions in 0.25% carboxymethylcellulose (CMC)
and administered through oral route.
(FBS) (Gibco;
# 10437036) was obtained from Invitrogen
BioServices India Pvt. Ltd., Bangalore, KA, India; 5-fluorouracil (5-
FU) was procured from Biochem Pharmaceutical Industries Ltd.,
Mumbai, MH, India. All chemicals and buffers for Western blotting
were obtained from Bio-Rad Laboratories Inc., Hercules, CA, USA.
Bax (# 2772S), Bcl-2 (# 2876S), GAPDH (# 2118S), Anti-rabbit
IgG HRP-linked (# 7074S) antibodies were procured from Cell
Signaling Technology Inc., Danvers, MA, USA. Tissue culture plastic
wares and materials were purchased from Tarsons Products Pvt.
Ltd., Bangalore, KA, India; Muse™ Annexin V & Dead Cell Kit
(Cat# MCH100105), Muse™ Caspase-3/7 Kit (# MCH100108)
(Merck KGaA, Darmstadt, Germany); 1,2-dimethylhydrazine
hydrochloride [DMH] (# D0742) from TCI Co. Ltd., Tokyo, Japan;
IL-6 ELISA kit (# KRC3011), TNF-a ELISA kit (# KRC3011) was pur-
chased from Invitrogen BioServices India Pvt. Ltd., Bangalore, KA,
India. All other reagents, chemicals and solvents used in study
were of analytical grade quality.
Please cite this article in press as: N.D. Reddy et al., In vitro and in vivo evaluation of novel cinnamyl sulfonamide hydroxamate derivative against colon
adenocarcinoma, Chemico-Biological Interactions (2015), http://dx.doi.org/10.1016/j.cbi.2015.03.015

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2.5. General synthetic procedure for cinnamyl sulfonamide
hydroxamate derivatives
tetrahydrofuran (THF) solvent and the reaction mixture was then
stirred at 35 °C for 2 h and further partitioned between ethyl acet-
ate and 2 M HCl. The ethyl acetate layer was washed successively
with distilled water and evaporated. The residue was purified by
silica gel column chromatography to obtain final product 4
(Fig. 1) [13].
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2.5.1. Synthesis of (E)-3-(4-(chlorosulfamoyl)phenyl)acrylic acid
Cinnamic acid 1 (Fig. 1) (0.05 mM) and chlorosulfonic acid
(0.5 M) were stirred at 35 °C for 4 h. Pre-coated TLC plates were
used to monitor the reaction progress. The viscous reaction mix-
ture was poured into ice cubes contained in a beaker. The yel-
low-colored precipitate that was formed was filtered, washed
with distilled water and dried in vacuo (anhydrous CaCl2). The
crude product was recrystallized from dioxane as 2 (Fig. 1) [11].
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2.6. Characterization of cinnamyl sulfonamide hydroxamate
derivatives
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2.6.1. (E)-N-hydroxy-3-(4-(N-(thiophen-2yl)methyl)sulfamoyl)phenyl)
acrylamide [NMJ-1]
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2.5.2. Synthesis of (E)-3-(4-(N-(2-(thiophen-2yl) methyl) or
(thiophen-2yl)ethyl) or furan-2yl)methyl) sulfamoyl)phenyl)acrylic
acid
To a suspension of 2 (Fig. 1) (7.7 mM) in distilled water, thio-
phene methyl amine (7.7 mM) or thiophene ethyl amine or fur-
furylamine was added and maintained at pH 8 with aqueous
NaHCO3. The reaction mixture was stirred at 35 °C for 4 h. The mix-
ture was then brought to pH 2 by the drop wise addition of 12 M
HCl. The product 3 (Fig. 1) obtained as a white precipitate was
washed, dried and recrystallized [12].
Yield = 76%. m.p. uncorrected 178 2 °C; Rf value 0.70. IR (KBr);
3284 (OH), 3209 (NAH 2°), 1672 (C@O carboxylic), 1313, 1180
(O@S@O), 690 (CAS) cmÀ1 respectively. 1H NMR (400 MHz,
,
DMSO(D6)) d 10.87 (1H, s), 9.1(1H, s), 8.3–7.7 (3H, m), 7.5–6.8
(4H, m), 6.6 (1H, d), 6.5 (1H,d), 4.1(3H,s), 1.20 (1H,d) ppm; 13C
NMR (400 MHz, DMSO(D6)) d 162.6 (NAC@O), 141.04 (CAS),
137.1 (CAS), 128.5–126.1 (6CAC), 41.74 (CAN) ppm; CHN-S
Elemental analysis: C – 54.28% H – 4.57% N – 8.22% S – 20.51%
MS (ESI): m/z = 339.0
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2.5.3. Synthesis of (E)-N-hydroxy-3-(4-(N-(thiophen-2yl)methyl) or
(thiophen-2yl)ethyl) or furan-2yl)methyl)sulfamoyl)phenyl)-
acrylamide
2.6.2. (E)-N-hydroxy-3-(4-(N-(thiophen-2yl)ethyl)sulfamoyl)phenyl)-
acrylamide [NMJ-2]
Yield = 74%. m.p. uncorrected 150 2 °C; Rf value 0.65. IR (KBr);
3288 (OH), 3205 (NAH 2°), 1691 (C@O carboxylic), 1334, 1168
To a suspension of 3 (Fig. 1) (10 mM) in dichloromethane
(Cl2CH2), ethylchloroformate (12 mM) and N-methylmorpholine
(13 mM) were added under anhydrous condition using calcium
chloride guard tube and the reaction mixture was then stirred at
35 °C for 5 h. The complete conversion of acrylic acid to acid
chloride was monitored on pre-coated TLC plates. The simultane-
ous reaction of conversion of acid chloride to hydroxamate was
completed by adding neutral solution of hydroxylamine in
(O@S@O), 692 (CAS) cmÀ1 respectively. 1H NMR (400 MHz,
,
DMSO(D6)) d 8.32 (1H, s), 7.79 (1H, s), 7.49–7.29 (3H, m), 6.93–
6.84 (4H, m), 6.61 (1H, d), 6.51 (1H,d), 4.15(2H,s), 3.9 (2H,s) 1.15
(1H,d) ppm; 13C NMR (400 MHz, DMSO(D6)) d 162.1 (NAC@O),
140.9 (CAS), 138.9 (CAS), 128.3–125.5 (6CAC), 44.32 (CAN)
ppm; CHN-S Elemental analysis: C – 49.02% H – 6.64% N – 7.0% S
– 18.29% MS (ESI): m/z = 350.9
O
O
OH
a
OH
Cl
S
O
O
2
Cinnamic acid
1
d
c,
b,
O
OH
H
N
R
S
O
O
3
e,
f, g
h, i,
j
O
OH
NH
H
N
R
S
O
O
4
Fig. 1. Synthesis scheme of (E)-N-hydroxy-3-(4-(N-(2-(thophen-2yl)ethyl) sulfamoyl)phenyl)acrylamide. Reagents and conditions: (a) chlorosulfonic acid; stirred mixture at
35 °C for 4 h, (b) thiophene ethyl amine or thiophene methyl amine or furfurylamine, (c) double distilled water, (d) aq. Na2CO3; pH maintained at 8 and stirred for at 35 °C for
4 h, (e) ethylchloroformate, (f) CH2Cl2, (g) cat. N-methylmorpholine; maintained anhydrous condition and stirred 5 h, (h) NH2OH, (i) CH3OH and (j) aq. NaOH; stirred mixture
for 2 h.
Please cite this article in press as: N.D. Reddy et al., In vitro and in vivo evaluation of novel cinnamyl sulfonamide hydroxamate derivative against colon
adenocarcinoma, Chemico-Biological Interactions (2015), http://dx.doi.org/10.1016/j.cbi.2015.03.015

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2.6.3. (E)-N-hydroxy-3-(4-(N-(furan-2yl)methyl)sulfamoyl)phenyl)-
acrylamide [NMJ-3]
stained cells were analyzed using Accuri C6 flow cytometer (BD
Biosciences, San Jose, CA, USA) using excitation at 488 nm and
emission at 575/40 nm. A minimum of 10,000 events were
acquired for each sample and data analysis was done by using
BD Accuri™ C6 software [17].
Yield = 78%. m.p. uncorrected 138 2 °C; Rf value 0.63. IR (KBr);
3289 (OH), 3209 (NAH 2°), 1685 (C@O carboxylic), 1327, 1180
(O@S@O), 695 (CAS) cmÀ1 respectively. 1H NMR (400 MHz,
,
DMSO(D6)) d 10.92 (1H, s), 9.2 (1H, s), 8.2–7.87 (3H, m), 7.7–6.6
(4H, m), 6.5 (1H, d), 6.2 (1H,d), 4.03 (3H,s), 1.23 (1H,d) ppm; 13C
NMR (400 MHz, DMSO(D6)) d 166.9 (NAC@O), 150.2 (CAS), 142.7
(CAS), 128.6–126.7 (6CAC), 40.1 (CAN) ppm; CHN-S Elemental
analysis: C – 42.97% H – 3.62% N – 5.93% S – 8.06% MS (ESI): m/
z = 320.9
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2.7.5. Early and late apoptosis detection by Annexin V staining
In brief, as per Annexin V flow cytometry kit protocol, 1 Â 106
cells were seeded in 25 cm2 flasks and after overnight adherence,
incubated with test compounds. Then cells were detached by
trypsinization and mixed with floating cells, centrifuged and
washed with PBS. Cell suspension (100
ll) was mixed with Muse
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2.7. Cell culture and treatment
Annexin V and Dead Cell kit reagent (100
ll) and incubated for
20 min at room temperature. The stained cells were quantitatively
analyzed for live, early and late apoptosis and dead by using Muse
Cell Analyzer (# 0500-3115 Merck Millipore) with Annexin V kit (#
MCH100105 Merck Millipore) [18].
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2.7.1. Cell viability study by MTT assay
In brief, 70% confluent cultured flask containing 5 Â 103 cells/
100 ll cells were plated in 96-well plates and allowed to attach
cells at bottom by keeping plates overnight in incubator. Then cells
were exposed to different concentrations of compound for 48 h.
After the incubation, MTT reagent 10 ll (5 mg/ml in PBS) was
added and cells incubated for an additional 3 h. The formazan crys-
tals formed by the viable cells were solubilized by addition of
DMSO and plate absorbance was measured at 540 nm using micro-
plate ELISA reader (ELx800, BioTek Instruments Inc., Winooski, VT,
USA) [14]. The IC50 for compound was determined by using Prism
5.03 Demo Version (GraphPad Software Inc., La Jolla, CA, USA).
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2.7.6. Detection of caspase 3/7 activation
In brief, as per caspase 3/7 activation flow cytometry kit proto-
col, 1 Â 106 cells were seeded in 25 cm2 flasks and after overnight
adherence, incubated with the test compounds. Then cells were
detached by trypsinization and mixed with floating cells, cen-
trifuged and washed with PBS. Cell suspension (50
with Caspase-3/7 antibody reagent (5 l) and incubated at 37 °C
temperature for 30 min. 7-AAD working solution (150 l) was
ll) was mixed
l
l
added and stained cell were analyzed in Muse Cell Analyzer (#
0500-3115 Merck Millipore) with Caspase 3/7 kit (# MCH100108
Merck Millipore) [18].
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2.7.2. Whole cell HDAC enzyme assay
In brief, 2 Â 104 cells were seeded in 50
ll in 96-well standard
sterile black plates and incubated over night at 37 °C with 5% CO2
in incubator. The cells were incubated for 18 h with different con-
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2.7.7. Western blot analysis
centration of compounds. Then, 2
substrate was added and incubated for 1 h at 37 °C with 5% CO2
in an incubator. The reaction was stopped by adding 100
ll of 15 mM Boc-Lys(Ac)-AMC
In brief, the whole-cell extract was generated from cell pellets
in mammalian protein extraction buffer supplemented with pro-
tease and phosphatase inhibitor cocktail. The protein quan-
tification was done by using commercial protein estimation
BCA™ kit (Thermo Fisher Scientific Inc., Waltham, MA, USA) and
l
l
HADC assay buffer containing 2 mg/ml of trypsin and 1% NP-40.
The reaction was allowed to proceed for 15 min at 37 °C with 5%
CO2 in incubator and the fluorescence was taken at excitation
360 nm and emission 460 nm by using fluorescence microplate
reader (FLx800, BioTek Instruments Inc., Winooski, VT, USA) [15].
The IC50 for compound was determined by using fully functional
Prism 5.03 Demo Version (GraphPad Software Inc., La Jolla, CA,
USA).
protein samples (20
l
g) were dissolved in 5Â sample loading buf-
fer and DTT (100 mg/ml) and boiled for 5 min at 99 °C. This was
resolved on a 10% SDS–PAGE and blotted on to a PVDF membrane
and blocked with 5% non-fat milk protein in TBS-T buffer for 1 h at
room temperature. The primary antibodies (anti-rabbit Bax, anti-
rabbit Bcl-2 and anti-rabbit GAPDH) were probed overnight at
4 °C. After washing with TBS-T buffer, the horseradish peroxi-
dase–conjugated secondary antibody was subsequently incubated
for 1 h at 25 °C room temperature. The signal was visualized by
using Pierce enhanced chemiluminescent (ECL) Western Blotting
Substrate kit (Thermo Fisher Scientific Inc., Waltham, MA, USA)
on medical grade X-ray film [19]. The relative densities were
quantified by using calibrated densitometer (GS 800, Bio-Rad
289
290
291
292
293
294
295
296
297
298
299
300
301
302
2.7.3. Hoechst 33342 and AO/EB (dual) nuclear staining
In brief, the 5 Â 103 cells/well were seeded in 24-well plates
with DMEM containing 10% FBS. After 24 h, cells were treated with
different concentration of compounds and incubated for 48 h. The
plate was washed with PBS, pH 7.4 and cells were fixed with ice-
cold methanol for 20 min. Then cells were washed with PBS again
and 300 ll of Hoechst 33342 stain (2 lg/ml) or AO/EB (20/30 lg/
ml) was added to each well. The plate was incubated at 37 °C for
20 min. Finally the plate was washed thrice with PBS and observed
Table 1
under
a
fluorescent microscope (Eclipse TS100-F, Nikon
List of cinnamyl sulfonamide-hydroxamate derivatives with different substitutions.
Instruments Inc., Melville, NY, USA) for morphological changes in
nucleus like condensed chromatin and fragmented nuclei. The
apoptotic index (AI) was calculated as % of apoptotic cells from
randomly counted 100 cells in each treatment group [16].
S.
no.
Compound
code
Heteroaromatic amines (R) Structure
Name
1
2
3
NMJ-1
NMJ-2
NMJ-3
Thiophene methyl amine
Thiophene ethyl amine
Furfurylamine
303
304
305
306
307
308
309
310
2.7.4. Cell cycle analysis
In brief, the 1 Â 106 cells were seeded in 25 cm2 flasks and after
overnight adherence, incubated with test compounds. Then cells
were detached by trypsinization and mixed with floating cells, cen-
trifuged and washed with PBS. The cell pellets were fixed in 70%
ice-cold methanol and stored at À20 °C for 24 h. After that cell pel-
lets were washed with PBS and isotonic PI solution [25
l
g/ml pro-
pidium iodide, 0.03% NP-40 and 40
l
g/ml RNase A] was added. The
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Table 3
357
358
Laboratories Inc., and Hercules, CA, USA) with Quantity One 1D
analysis software.
Effect of NMJ-1, 2, 3 and SAHA incubated for 18 h, on whole cell HDAC enzyme and its
correlation with apoptotic protein expression such as phosphatidylserine (Annexin
V), Bax/Bcl-2 ratio and activated caspase 3/7 in HCT 116 cells.
359
2.8. In vivo studies
S.
Compound Whole cell Phosphatidylserine Bax/ Caspase 3/7
no. name
HDAC
inhibition
IC50
(Annexin V)
(% early apoptosis) ratio
Bcl-2 (% apoptosis)
360
361
362
363
364
365
366
367
368
369
2.8.1. Acute toxicity studies
The safe dose was determined according to OECD-425; Limit
test dose (2000 mg/kg) was given p.o. to fasting female rats.
Animals were observed for toxic signs for the first 4 h continuously
and then daily observed for 14 days.
There was no mortality with 2000 mg/kg dose of NMJ-2. The
external morphological, behavioral, neurological profile was found
to be normal. Thus, NMJ-2 passed limit test and was found to be
safe up to 2000 mg/kg dose level. So, 1/20th dose, i.e. 100 mg/kg,
p.o. was selected for efficacy studies.
(lM
SEM)
1
Normal
–
4.8
0.308 21.55
control
5-FU
SAHA
NMJ-1
NMJ-2
NMJ-3
2
3
4
5
6
–
13.95
1.010 56.10
1.573 43.50
2.63 0.07 14.30
3.89 0.17
0.41 0.01 12.0
5.85 0.79
–
–
–
1.708 79.75
–
–
–
370
371
372
373
2.8.2. DMH (1,2-dimethyl hydrazine) induced colon cancer in Wistar
rats
2.8.2.1. Experimental design. Animals were divided into 4 groups
and dose was administered as follows:
403
404
405
406
407
stereo microscope (40Â magnification). ACFs were clearly defined
as microscopically elevated slit-like opening with a thick epithelial
lining that deeply takes up the stain in the vicinity of the cryptal
zone that was larger than normal crypts. ACF were counted and
calculated as number of counts/5 cm2 [21].
374
375
376
377
378
379
ꢀ Normal control (sham control)
ꢀ DMH control [0.25% CMC, p.o. 10 ml/kg and saline i.p. 1 ml/kg]
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
2.8.2.4. Biochemical parameters. 10% homogenate of colon tissue
was prepared in ice cold mammalian tissue lysis buffer supple-
mented with protease and phosphatase inhibitor cocktail using a
homogenizer (RQ-124A/D, REMI Laboratory Instruments,
Mumbai, India). The homogenate was centrifuged by using cooling
(DMH + vehicle)
ꢀ Standard drug (5-FU injection; 10 mg/kg, i.p.) (DMH + 5-FU)
ꢀ Test compound (NMJ-2; 100 mg/kg, p.o.) (DMH + NMJ-2)
centrifuge (MIKRO 22R, Andreas Hettich GmbH
& Co.KG,
380
381
382
383
384
385
386
387
388
389
390
2.8.2.2. Procedure. In brief, animals (Wistar rats) in the weight
range of 120–150 g were taken for study. DMH (1,2-dimethyl
hydrazine) 30 mg/kg body weight was given by i.p., once a week,
for 20 weeks [20]. After 20 weeks one animal from each group
was sacrificed and observed for incidence of aberrant crypt foci
(ACFs) and adenocarcinoma. Animals were randomized on the
basis of equal mean body weight throughout the groups and test
compound and standard drug were administered for 21 days. At
the end of the study, rats were sacrificed humanely and colons
were excised, blotted and dried. The following parameters were
estimated.
Tuttlingen, Germany) at 14,000 rpm for 10 min at 4 °C and the pel-
lets were discarded. The supernatant was used for total protein
estimation, using BCA™ commercial kit (Thermo Fisher Scientific
Inc., Waltham, MA, USA), TNF-a (ELISA kit # KRC3011,
Invitrogen) and IL-6 (ELISA kit # KRC3011, Invitrogen) [22], nitrite
and nitrate estimation.
Nitrite, total nitrate + nitrite contents were estimated by Griess’
reagent method, adopting the established procedure [23,24].
Nitrate was reduced into nitrite by using acidic solution of vana-
dium (III) chloride and mild heat.
Nitrite estimation: 100 ll of Griess’ reagent and 100 ll of super-
natant were incubated at 37 °C in 96 well plates for 20 min and
absorbance was measured at 540 nm. The amount of nitrite was
quantified from sodium nitrite standard curve.
391
392
393
394
395
396
ꢀ ACF, adenocarcinoma incidence and count
ꢀ Biochemical parameters
ꢀ Organ index
Total nitrate + nitrite estimation: 100
of supernatant and 100 l of vanadium (III) chloride (0.8% in 1 N
HCl) were incubated in microcentrifuge tubes at 45 °C for 60 min.
100 l of each of the samples were added into 96 well plates and
ll of Griess’ reagent, 100 ll
ꢀ Hematological parameters
ꢀ Histopathology of colon
l
l
absorbance was measured at 540 nm.
Nitrate contents were calculated by subtracting nitrite values
from total nitrate + nitrite contents.
397
398
399
400
401
402
2.8.2.3. ACF, adenocarcinoma incidence and count. Initially, the
entire colon was observed for adenocarcinoma. If present, the
count and size from each animal was noted. The distal colon tissue
(5 cm2) was cut open and fixed flat on filter paper and fixed with
10% buffered formalin for 12 h and then stained with 0.1% of
methylene blue in PBS for 5 min. Specimens were observed under
435
436
2.8.2.5. Organ index. Colons were isolated, length was measured in
cm and weight was measured in g and the colon weight/length
Table 2
Effect of treatments on the proliferation of different cells after 48 h.
S. no.
Cell line
Cytotoxicity assay compound incubation time for 48 h
IC50 SEM)
(lM
5-FU
SAHA
NMJ-1
NMJ-2
NMJ-3
1
2
3
4
5
6
7
HCT 116
MCF-7
MDA-MB-231
HepG2
PC3
SH-SY5Y
Vero
22.0 0.35
23.7 2.2
33.4 1.1
8.8 0.8
30.2 0.47
5.3 0.43
45.0 3.0
3.1 0.35
5.2 0.1
3.8 0.25
11.7 1.1
2.4 0.3
5.07 0.9
5.3 0.3
4.4 0.2
9.8 1.3
5.6 0.5
4.5 0.6
9.7 1.7
3.3 0.15
5.5 0.3
3.9 0.3
4.1 0.6
5.8 0.2
3.6 0.3
8.2 1.0
17.3 0.9
26.8 2.0
21.7 1.7
44.9 2.6
18.6 0.9
20.1 0.42
15.1 1.5
4.7 0.52
5.1 0.2
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Fig. 2. The representative images for induction of apoptosis by different treatments for 48 h in HCT 116 cells. Apoptotic index was calculated by counting specific pattern of
condensed and fragmented nuclear morphology. Figure A: Hoechst 3342 staining, B: AO/EB staining. Graph A: Hoechst 3342 staining, B: AO/EB staining. All values are
mean SEM of three samples, ap < 0.05 vs normal control.
437
438
448
449
450
451
452
453
ratio was calculated. Spleen and liver were isolated, weighed in g
and spleen index and liver index were calculated.
Sections were spread in a temperature regulated tissue float
(Model 375, Lipshaw Manufacturing Corporation, Detroit, MI,
USA) and fixed on clean slides pre-coated with egg albumin. The
sections were stained with methylene blue, Harris hematoxylin,
counter stained with eosin and mounted in DPX and scored for
gross anatomical and histopathological changes.
439
440
441
442
2.8.2.6. Hematological parameters. Blood was collected into di-
potassium EDTA-coated vacutainers from the retro-orbital plexus
and analyzed for various circulatory blood cells by using veterinary
blood cell counter (Model PCE-210 VET, ERMA Inc., Tokyo, Japan).
443
444
445
446
447
454
455
456
457
458
2.8.2.7. Histopathology of colon. The colon tissue was fixed in 10%
neutral buffered formalin for 24 h and dehydrated with alcohol.
The tissue was then cleared in xylene and paraffin-embedded.
Five micron thick sections were cut using a rotary microtome
(RM2245, Leica Microsystems GmbH, Wetzlar, Germany).
2.8.2.8. Statistical analysis. Statistical analysis of the data was done
by one-way ANOVA followed by the Tukey’s post hoc test using
fully functional Prism 5.03 Demo Version (GraphPad Software
Inc., La Jolla, CA, USA). A value of p < 0.05 was considered to be
significant.
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Fig. 3. Effect on the cell cycle of HCT 116 after 48 h treatment. The % cells in specific G0/G1, S and G2/M phase was estimated the by flow cytometry. (A) FSC vs SSC plot for
normal control population, (B) width vs FL2-A plot for 2n to 4n normal control gated population, (C) FL2-A vs count histogram plot for normal control (0.01%), (D, E and F) FL2-
A vs count histogram plots for 5-FU (10 lM), SAHA (5 lM) and NMJ-2 (5 lM) respectively.
488
489
490
491
its IC50 of 3.3 0.15 lM and had 2.5-fold selectivity towards
459
3. Results and discussion
human colon adenocarcinoma cells (HCT 116) over normal kidney
epithelial cells (Vero). The above result showed its selective cyto-
toxicity towards cancerous cells compared to normal cells.
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
The present study explored the anti-cancer potential of three
novel cinnamyl sulfonamide hydroxamate derivatives [NMJ series]
against the target enzyme, HDAC by a series of in vitro and in vivo
screening models of colon adenocarcinoma. A number of different
approaches were adopted to establish the anti-cancer and anti-in-
flammatory effects of NMJ-2, which showed the maximum efficacy
out of the three tested compounds.
A number of targets have multiple roles in the complexities of
carcinogenesis, which may be biochemically mediated, genetically
predisposed and epigenetically controlled. Overexpressed HDAC is
responsible for sustaining the levels of deacetylated histones,
which in turn, are responsible for activation of tumor promoter
gene and inactivation of tumor suppressor genes [7]. This was
selected as a target for the development of newer therapies
(Table 1).
492
3.2. Whole cell HDAC enzyme assay
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
The interaction of HDAC enzyme with associated protein,
mainly histone, present in intact nuclei of cells, is a complex
physiological process. However, isolated, recombinant and purified
enzyme interaction solely with the test compound will not give
any clear picture regarding the natural protein–protein interac-
tions. To overcome this limitation, whole cell HDAC assay provides
a better insight in understanding the natural protein–protein inter-
actions in intact cells or tissues and further helps in simulating the
physiological system [25]. Thus, the same has been employed in
the present study to assess the inhibition activity of the NCEs on
HDAC.
The whole cell HDAC enzyme inhibition activity of NMJ-2
(being the most potent one) was compared with that of the stan-
dard, SAHA (marketed HDAC inhibitor), as shown in Table 3. A dose
dependent HDAC inhibition was clearly observed with NMJ-2.
Besides, it had higher potency than the standard SAHA. The whole
cell HDAC enzyme inhibition IC50 of NMJ-2 and SAHA were about
475
3.1. Cell viability study by MTT assay
476
477
478
479
480
481
482
483
484
485
486
487
The pre-requisite for any chemical scaffold to show anti-cancer
activity is that the compounds should primarily be cytotoxic to
cancer cells. Generally anti-cancer activity of the test compounds
is primarily evaluated by their cytotoxic potential in different types
of cancer cell lines. The anti-cancer potential of NMJ-1, 2, 3 was
evaluated against six different human cancer cell lines in vitro by
MTT cytotoxicity assay after 48 h of incubation with the following
drugs viz. 5-FU, SAHA and test compounds NMJ-1, 2, 3 is shown in
Table 2. The three test compounds NMJ-1, 2, 3 showed growth
0.41 0.01 and 2.63 0.07 lM, respectively, as shown in Table 3.
511
3.3. Hoechst 33342 and AO/EB (dual) nuclear staining
512
513
514
515
Both the fluorescent nuclear staining dyes have the property of
permeation into cells and hence are used to study the morphologi-
cal features of nuclear DNA or RNA. The mechanism underlying the
cell death induced by test compounds in HCT 116 was confirmed
inhibition IC50 at a range of 3.3 0.15–44.9 2.6 lM. NMJ-2, was
more cytotoxic than 5-FU and comparable with that of SAHA.
NMJ-2 was more active against HCT 116 (highly metastatic) with
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Fig. 4. Effect on Annexin V surface binding in HCT 116 cancer cells after 48 h treatment. Apoptosis profile was assessed as % live, early, late apoptosis and dead cells by flow
cytometry. (A) Population profile for normal control (0.01%); (B, C, D and E) Annexin V staining apoptosis profile for normal control, 5-FU (10 M), SAHA (5 M) and NMJ-2
(5 M), respectively.
l
l
l
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
543
544
545
546
547
548
549
550
551
552
by these fluorescent dyes. Hoechst 33342 indicates the DNA frag-
mentation or chromatin condensation whereas AO/EB (dual) stain-
ing facilitates visualization of apoptotic changes and/or necrosis.
The hallmark features of Hoechst 33342 staining included the pres-
ence of fragmented nuclear DNA (seen as visible cluster of blue
spots) and condensed chromatin (appear as a bright blue colored
intense spot). However, in case of AO/EB stain, the cells appear
as green colored distinct spots for viable cells, yellow color for
early apoptotic cells and reddish to orange staining for the late
apoptotic cells [26].
The normal control (0.01% DMSO) showed the apoptotic index
about 3.3 0.88 and 5.0 1.0% with Hoechst 33342 and AO/EB
(dual) staining, respectively. Further, NMJ-2 treatment showed
dose dependent significant increase in apoptotic index and was
comparable with that of the standard SAHA and 5-FU as shown
in Fig. 2.
G0/G1, S and G2/M phase. The normal control showed the dis-
tribution of cells in G0/G1, S and G2/M phase as 70.9%, 11.6% and
16.5% cells, respectively. However, the standard drug, 5-FU at
10
(74.7%), indicating clearly the cell cycle arrest. SAHA (5
NMJ-2 (5 M) treatments showed increase in cell population at
l
M treatment caused accumulation of cells in G0/G1 phase
l
M) and
l
36.1% and 35.5% cells, respectively in G2/M phase (Fig. 3). This is
an indication that cell cycle of the cancer cells is arrested in G2/
M phase by the compounds perhaps due to overexpression of nega-
tive cell cycle regulators through HDAC inhibition.
553
3.5. Early and late apoptosis detection by Annexin V staining
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
Annexin V is a cellular protein exclusively used for staining pur-
pose in the detection of apoptosis. In this method, Annexin V is
combined with propidium iodide. Generally Annexin V helps the
early detection of apoptosis whereas the combined stain would
enable the detection of the late stage of apoptosis. This protein
has affinity to bind with the phosphatidylserine (PS) which is
located along the cytosolic side of the plasma membrane in healthy
cells. Whenever apoptosis is initiated, PS translocates into the
extracellular membrane after which Annexin V interacts and thus
facilitates the identification of various stages of apoptosis [29]. In
the early stages, only Annexin V would bind to the surface protein
while in the later stage of apoptosis, there would be loss in the cell
membrane integrity allowing Annexin V to further bind to cytoso-
lic PS along with cellular uptake of propidium iodide. These
changes are clearly identified by flow cytometry. The test com-
pound, NMJ-2, significantly promoted the early and late stages of
532
3.4. Cell cycle analysis
533
534
535
536
537
538
539
540
541
542
The cell cycle involves different phases such as G0–G1, S, G2 and
M with check point at G1 (restriction point), G2 check point and M
(metaphase) check point. These check points play an important
role, working as sensors to assess the extent of DNA damage
caused by the external factors and facilitate the cell’s need to
undergo proliferation or apoptosis. If the arrest in the cell cycle
continues, it could either repair the damaged DNA or induce apop-
tosis if the repair of damaged DNA does not happen [27,28].
The effects of the compounds on cell cycle were assessed using
flow cytometry and the result of the same was shown as % cells in
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Fig. 5. Effect on caspase 3/7 activation in HCT 116 cancer cells after 48 h treatment. Apoptosis profile was assessed as % live, early, late apoptosis and dead cells by flow
cytometry. (A) Population profile for normal control (0.01%); (B, C, D and E) caspase 3/7 activation profile for normal control, 5-FU (10
respectively.
lM), SAHA (5 lM) and NMJ-2 (5 lM),
570
571
594
595
596
597
598
apoptosis and the effects were comparable with that of the stan-
dard drugs, SAHA and 5-FU, as shown in the Fig. 4.
NMJ-2 showed a 3-fold increase in Bax expression and 1.2, 1.8
and 1.9-fold decrease in Bcl-2 expression, respectively when com-
pared with that of the normal control. The ratio of Bax/Bcl-2 was
increased by 3.2, 5.0 and 5.5 folds with 5-FU, SAHA and NMJ-2,
respectively (Fig. 6).
572
3.6. Detection of caspase 3/7 activation
573
574
575
576
577
578
Caspases are the central regulators of programmed cell death.
The effector caspase 3/7 activation plays a very important role in
the initiation of apoptosis [30]. Our study on caspase activation
revealed that the test compound, NMJ-2 increased early and late
stages of apoptosis and its activity was comparable with standard
drugs, SAHA and 5-FU as shown in the Fig. 5.
599
600
3.8. Correlation of HDAC enzyme inhibition with apoptotic protein
expressions
601
602
603
604
605
606
607
608
The HDAC enzyme inhibition is correlated with apoptotic pro-
tein expression such as phosphatidylserine (Annexin V), Bax/Bcl-
2 ratio and activated caspase 3/7. NMJ-2 treatment resulted in
HDAC enzyme inhibition which led to increased Bax/Bcl-2 ratio
and increased activation of caspase 3/7 leading to apoptosis. The
expression levels of phosphatidylserine in NMJ-2 were comparable
with that of 5-FU and SAHA. Hence, NMJ-2 seems to be a more
potent HDAC inhibitor than SAHA, NMJ-2 and NMJ-3 (Table 3).
579
3.7. Western blot analysis
580
581
582
583
584
585
586
587
588
589
590
591
592
593
Bcl-2 gene family members are the most important regulators
of apoptosis. Bax and Bcl-2 have apoptosis induction and inhibition
roles, respectively [31]. The pro-apoptotic action of Bax protein is
dependent on the formation of Bax homodimers on the outer
mitochondrial membrane. The antagonistic effect of Bcl-2 protein
is by preventing the formation of Bax homodimers [32]. The cellu-
lar Bax/Bcl-2 ratio is a key factor in the regulation of apoptosis; a
low Bax/Bcl-2 ratio makes cells resistant to apoptotic signal, while
a high ratio induces cell death [32,33]. The Bax protein induces
apoptosis through the opening of mitochondrial voltage-gated
anion channels [34], which further raises the mitochondrial outer
membrane permeability. This leads to the release of cytochrome
c that triggers the activation of effector caspases 3 and 7 [35]. In
the present study, all the three treatments, i.e. 5-FU, SAHA and
609
610
3.9. DMH (1,2-dimethyl hydrazine) induced colon cancer in Wistar
rats
611
612
613
614
615
616
617
The development of colon cancer involves three important
phases. In the initiation phase, a single mutation leads to the
abnormal proliferation of cells. Next, additional mutations lead to
the proliferation of selected transformed cells within the pop-
ulation in the promotion phase. Finally, in the progression phase,
multiple mutated tumor clone cells produce malignant tumors.
Thus, the sequence of events consists of phases for both prevention
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Fig. 6. Effect of 5-FU, SAHA and NMJ-2 incubated for 48 h, on Bax, Bcl-2 protein expression in HCT 116 cells. The relative integrated density of Bax/GAPDH, Bcl-2/GAPDH and
Bax/Bcl-2 ratio was calculated using calibrated densitometer with Quantity One 1D analysis software. All values were mean SEM of three samples, ap < 0.001 as compared to
normal control and bp < 0.001 as compared to 5-FU (standard).
Table 4
Effect of DMH + 5-FU (10 mg/kg, i.p.) and DMH + NMJ-2 (100 mg/kg, p.o.) administration for 21 days on ACF incidence and count; adenocarcinoma count and size (measured by
Vernier caliper). All values are mean SEM, n = 6.
S. no. Group
ACF incidence (%) No. of ACF/5 cm2 (mean SEM) Adenocarcinoma
Small ꢁ(0.1–2 mm) Medium ꢁ(2–4 mm) Large ꢁ(4–8 mm) Total
1
2
3
4
Normal control
DMH + Vehicle
DMH + 5-FU (10 mg/kg)
DMH + NMJ-2 (100 mg/kg) 100.0
0
0
0
7
4
5
0
6
3
2
0
4
1
2
0
17
8
100.0
100.0
84.25 7.6a
58 5.0a,b
64.5 6.7a,b
9
a
p < 0.05 vs normal control.
p < 0.05 vs DMH control.
b
618
619
620
621
622
623
624
625
626
627
628
629
and intervention [36]. Further, in human cancer development, gene
mutation is associated with chronic inflammation which is consid-
ered one of the major risk factor [37].
DMH, a chemical carcinogen, is known to cause colon cancer in
a reproducible in vivo experimental system for studying sporadic
(non-familial) forms of colon carcinoma where, DMH is converted
to its final carcinogenic metabolite such as diazonium ions, azoxy-
methane (AOM) and methylazoxymethanol (MAM) by NAD+-de-
pendent dehydrogenase enzyme. Further, these intermediates,
alkylate (methylation) colonic mucosal DNA and generate oxida-
tive stress. This results in a delayed or incomplete repair of dam-
aged DNA leading to the accumulation of multiple mutations
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Fig. 7. Effect of DMH + 5-FU (10 mg/kg, i.p.) and DMH + NMJ-2 (100 mg/kg, p.o.) administration for 21 days on inflammatory markers. (A) Nitrite, (B) nitrate, (C) IL-6 and (D)
TNF-
contents in colon tissue homogenate. All values are mean SEM of six samples. ap < 0.05 vs normal control, bp < 0.05 vs DMH control.
a
Fig. 8. Effect of DMH + 5-FU (10 mg/kg, i.p.) and DMH + NMJ-2 (100 mg/kg, p.o.) administration for 21 days on organ index. (A) Spleen index, (B) liver index, (C) colon weight/
length ratio. All values are mean SEM of six samples. ap < 0.05 vs normal control, bp < 0.05 vs DMH control.
Please cite this article in press as: N.D. Reddy et al., In vitro and in vivo evaluation of novel cinnamyl sulfonamide hydroxamate derivative against colon
adenocarcinoma, Chemico-Biological Interactions (2015), http://dx.doi.org/10.1016/j.cbi.2015.03.015

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Fig. 9. Effect of DMH + 5-FU (10 mg/kg, i.p.) and DMH + NMJ-2 (100 mg/kg, p.o.) administration for 21 days on blood profile. (A) WBC count, (B) RBC count, (C) granulocytes
count, (D) platelet count. All values are mean SEM of six samples. ap < 0.05 vs normal control, bp < 0.05 vs DMH control.
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such as Apc, K-ras, b-catenin and thus leads to susceptibility of
specific adenocarcinoma of colon [38–40]. The following parame-
ters were monitored in this model.
NO metabolites in biological samples provides valuable informa-
tion about nitrosative and nitrative stress. In blood, plasma, other
physiological fluids, tissue homogenates or buffers, metabolites
of NO remain stable for several hours and can be estimated by dif-
ferent methods [43].
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3.9.1. ACF, adenocarcinoma incidence and count
From our study, it was observed that DMH control had raised
Aberrant crypt foci (ACF) are well accepted biomarkers for the
detection of colon cancer [41]. The ACF count helps in the analysis
of the extent of damage to the mucosa of colon by DMH treatment.
In this present study, DMH control showed 100% ACF incidence
throughout treatment groups whereas, in normal control the inci-
dence was 0%. Further, tissue sections from distal 5 cm2 of colon
tissues were selected and the ACFs in all the treatment groups such
as DMH control, 5-FU and NMJ-2 were observed as 84.24 7.6,
58.5 1.0 and 64.5 6.7, respectively. Besides, the number of
ACFs were also significantly (p < 0.05) reduced (about ꢁ30%) in
both 5-FU and NMJ-2 treated groups as compared with that of
DMH control. The colon adenocarcinoma was found in all the treat-
ment groups. However, 5-FU and NMJ-2 treatment shown a 50%
reduction in adenocarcinoma count when compared with that of
DMH control as shown in Table 4. NMJ-2 showed comparable
anti-cancer efficacy with the standard 5-FU.
TNF-
control as shown in Fig. 7. It was found that in DMH control there
was a 20-fold increase in TNF- level. However, the IL-6 level was
a, IL-6, nitrite and nitrate contents as compared to normal
a
increased by 10-fold when compared with that of normal control.
Further, 5-FU and NMJ-2 treatment led to a significant (p < 0.05)
decrease in the TNF-a, IL-6, nitrite and nitrate contents as com-
pared to DMH control.
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3.9.3. Organ index
A rise in the colon weight/length ratio indicates colonic edema
or hyperplasia due to tissue injury or inflammation leading to
development of micro adenomas, adenomas and adenocarcinomas
[44]. In the present study, the rat colon weight/length ratio was
significantly increased (p < 0.05) in DMH control as compared with
normal control. However, in 5-FU and NMJ-2 treated groups, the
ratio was reduced but statistically not significant when compared
with DMH control (Fig. 8). No significant changes were observed
in liver and spleen indices in any of the treatment groups when
compared with normal and DMH controls.
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3.9.2. Biochemical parameters
TNF-a and IL-6 are known markers of tissue inflammation. The
metabolites of DMH formed in the liver are transported to colon via
bile and blood to cause methylation of colonic DNA leading to
oxidative stress and inflammation which eventually cause multiple
mutations in genes [40]. The major pathway for NO metabolism is
oxidation. This involves the step where NO is completely metabo-
lized to nitrite and nitrate in the body [42]. The quantification of
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3.9.4. Hematological parameters
None of the treatment groups had significant alterations in
WBC, RBC and granulocyte count. However, the total WBC count
was found to be slightly reduced in NMJ-2 treatment which was
Please cite this article in press as: N.D. Reddy et al., In vitro and in vivo evaluation of novel cinnamyl sulfonamide hydroxamate derivative against colon
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Fig. 10. Effect of DMH + 5-FU (10 mg/kg, i.p.) and DMH + NMJ-2 (100 mg/kg, p.o.) administration for 21 days on histopathology of colon. (A) Hematoxylin and eosin staining in
5
l
m colonic section (40Â); (B) methylene blue staining with 5
l
m colonic section (40Â); (C) methylene blue staining with formalin fixed 5 cm2 intact colon tissue (10Â). The
inflammatory lesions were indicated by stars and ACFs were indicated by arrows in hematoxylin and eosin (H and E) stained sections.
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statistically insignificant. A decrease in the granulocyte count was
observed with 5-FU and NMJ-2 compared to DMH control which
was statistically insignificant (Fig. 9). Further, it was observed that
there was a significant (p < 0.05) decrease in platelet count of DMH
control, 5-FU and NMJ-2 treatment compared to normal control.
findings showed that NMJ-2 acts through HDAC inhibition and
induction of intrinsic mitochondrial apoptotic pathway in colon
cancer cells. In vivo studies on DMH-induced colon adenocarci-
noma in rats showed a considerable reduction in ACFs and adeno-
carcinoma count, decreased inflammatory mediators (TNF-a, IL-6),
normal hematological parameters, organ index, anatomical and
histopathological characteristics of the colon. These results indi-
cate NMJ-2 as a promising anti-cancer agent with efficacy at par
with the existing standard 5-FU. The effect of the compound can
be further assessed in suitable transgenic cancer models to mimic
the human condition and to better understand its potential as a
drug.
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3.9.5. Histopathology of colon
The colon tissue of normal control had the usual histoarchitec-
ture with no signs of crypt abscess and dysplasia. However, in
DMH control group, it was observed that the colonic mucosa had
enlarged with crypt abscess, infiltration of inflammatory cells,
aberrant crypt foci formation and nuclear enlargement with ade-
nocarcinoma [40]. Hematoxylin–eosin and methylene blue stained
ACFs are shown by arrows in Fig. 10. Absence of mucosal crypt
abscess, reduced number of ACFs with putative pre-neoplastic
lesions and minimal infiltration of inflammatory cells were the
key features of 5-FU and NMJ-2 treatments.
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Conflict of Interest
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The author(s) declare(s) that they have no conflicts of interest to
disclose.
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4. Conclusion
Transparency Document
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Among the synthesized bio-isosters, NMJ-2, a thiophene deriva-
tive, was found to be the potent candidate for the treatment of
colon cancer in both in vitro and in vivo models. Our research
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The Transparency document associated with this article can be
found in the online version.
Please cite this article in press as: N.D. Reddy et al., In vitro and in vivo evaluation of novel cinnamyl sulfonamide hydroxamate derivative against colon
adenocarcinoma, Chemico-Biological Interactions (2015), http://dx.doi.org/10.1016/j.cbi.2015.03.015

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The authors would like to acknowledge the Department of
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adenocarcinoma, Chemico-Biological Interactions (2015), http://dx.doi.org/10.1016/j.cbi.2015.03.015