New chalcone-tethered 1,3,5-triazines potentiate the anticancer effect of cisplatin against human lung adenocarcinoma A549 cells by enhancing DNA damage and cell apoptosis

Article abstract of DOI:10.1016/j.bioorg.2020.104393

In the pursuit of new compounds for co-treatment to enhance the anticancer efficacy of cisplatin against lung adenocarcinoma, a series of chalcone-tethered 1,3,5-triazines was designed and synthesized. MTT assay was used to evaluate the anticancer activity of the combinations in which two hybrids 10 and 12 were found to significantly inhibit A549 cancer cells viability and their IC₅₀ values were 24.5 and 17 μM, respectively in reference to cisplatin (IC₅₀ = 21.5 μM). The combined effect of cisplatin with each of 10 and 12 was analyzed according to Chou-Talalay method against both A549 and normal human fibroblast cells. Mechanistic studies employing MALDI-TOF MS and fluorescence spectroscopy using Evagreen probe inferred that 10 and 12 induced DNA double strand breaks in contrast to cisplatin which induces DNA interstrand cross-links. Also, DNA damage kinetics study demonstrated the difference in the rate of DNA damage induced by both 10 and 12 alone and in combination with cisplatin. Further Annexin V-FITC/propidium iodide dual staining assay provided evidence that 10 and 12 induced apoptosis via different pattern to cisplatin and their combination with cisplatin promoted more cells to enter late apoptosis and necrosis. Molecular docking of 10 and 12 in the active pocket of DNA dodecamer displayed their binding modes with higher number of stable hydrogen bond donor as well as π-H interactions in reference to the original ligand.

Full text of DOI:10.1016/j.bioorg.2020.104393

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New chalcone-tethered 1,3,5-triazines potentiate the anticancer effect of cis-
platin against human lung adenocarcinoma A549 cells by enhancing DNA
damage and cell apoptosis
Marwa H. El-Wakil, Sherine N. Khattab, Amira F. El-Yazbi, Nefertiti El-
Nikhely, Ahmed Soffar, Hosam H. Khalil
PII:
S0045-2068(20)31691-6
DOI:
https://doi.org/10.1016/j.bioorg.2020.104393
YBIOO 104393
Reference:
To appear in:
Bioorganic Chemistry
Received Date:
Revised Date:
Accepted Date:
8 April 2020
6 October 2020
15 October 2020
Please cite this article as: M.H. El-Wakil, S.N. Khattab, A.F. El-Yazbi, N. El-Nikhely, A. Soffar, H.H. Khalil,
New chalcone-tethered 1,3,5-triazines potentiate the anticancer effect of cisplatin against human lung
adenocarcinoma A549 cells by enhancing DNA damage and cell apoptosis, Bioorganic Chemistry (2020), doi:
https://doi.org/10.1016/j.bioorg.2020.104393
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New chalcone-tethered 1,3,5-triazines potentiate the anticancer effect of
cisplatin against human lung adenocarcinoma A549 cells by enhancing DNA
damage and cell apoptosis
Marwa H. El-Wakila, Sherine N. Khattabb,c *, Amira F. El-Yazbid, Nefertiti El-Nikhelye,
Ahmed Soffarf, Hosam H. Khalilb
a
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Alexandria University, Alexandria
21521, Egypt.
b Department of Chemistry, Faculty of Science, Alexandria University, Alexandria 21321, Egypt.
c
Cancer Nanotechnology Research Laboratory (CNRL), Faculty of Pharmacy, Alexandria University,
Alexandria 21521, Egypt.
d
Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Alexandria University,
Alexandria 21521, Egypt.
e
Department of Biotechnology, Institute of Graduate Studies and Research, Alexandria University,
Alexandria 21526, Egypt.
f Department of Zoology, Faculty of Science, Alexandria University, Alexandria 21321, Egypt.
Corresponding author
*Sherine N. Khattab: Department of Chemistry, Faculty of Science, Alexandria University, Alexandria
21321, Egypt. Cancer Nanotechnology Research Laboratory (CNRL), Faculty of Pharmacy, Alexandria
University, Alexandria 21521, Egypt. E-mail: sh.n.khattab@gmail.com, sherinekhattab@alexu.edu.eg
Abstract
In the pursuit of new compounds for co-treatment to enhance the anticancer efficacy of cisplatin
against lung adenocarcinoma, a series of chalcone-tethered 1,3,5-triazines was designed and
synthesized. MTT assay was used to evaluate the anticancer activity of the combinations in which
two hybrids 10 and 12 were found to significantly inhibit A549 cancer cells viability and their IC50
values were 24.5 and 17 µM, respectively in reference to cisplatin (IC50= 21.5 µM). The combined
effect of cisplatin with each of 10 and 12 was analyzed according to Chou-Talalay method against
both A549 and normal human fibroblast cells. Mechanistic studies employing MALDI-TOF MS
and fluorescence spectroscopy using Evagreen probe inferred that 10 and 12 induced DNA double
strand breaks in contrast to cisplatin which induces DNA interstrand cross-links. Also, DNA
damage kinetics study demonstrated the difference in the rate of DNA damage induced by both 10
and 12 alone and in combination with cisplatin. Further Annexin V-FITC/propidium iodide dual
staining assay provided evidence that 10 and 12 induced apoptosis via different pattern to cisplatin
and their combination with cisplatin promoted more cells to enter late apoptosis and necrosis.
Molecular docking of 10 and 12 in the active pocket of DNA dodecamer displayed their binding
1

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modes with higher number of stable hydrogen bond donor as well as π-H interactions in reference
to the original ligand.
Keywords: 1,3,5-Triazinyl chalcones; Cytotoxicity; DNA damage; Molecular Docking;
Apoptosis
1. Introduction
Cancer is the second most deadly disease worldwide. The recent advances in cancer research
revealed cancer to be a disease characterized by dysfunction in the cell cycle mechanisms with
uncontrolled cell proliferation and migration [1]. Recent statistics reported 9.6 million deaths, out
of which, lung cancer accounted for nearly 2 million death cases. Lung cancer is now accepted as
the most fatal type of malignancies globally, particularly non-small cell lung cancer (NSCLC)
constituting 80-90 % of lung cancer cases [2].
Conventional methods for cancer treatment include surgery, radiotherapy and chemotherapy; in
which targeted chemotherapy has proven effectiveness in the treatment of various cancer types
and its ability to combat cancer cells resistance [3]. Chemotherapeutic agents targeting the DNA
constitute one of the most efficient classes of anticancer drugs that possess adequate clinical use
and provide enhanced patients’ survival rates either used solely or in combination with other drugs
[4]. Cisplatin is one of the effective anticancer agents usually directed in the treatment of a number
of solid tumors including ovarian, cervical, bladder and NSCLC carcinomas [5–7]. Water
solubility and the planar geometry of cisplatin facilitates its incorporation into the DNA double
strands forming interstrand cross links [8]. This causes toxic DNA lesions and inhibits DNA strand
separation thus halts DNA replication leading to apoptosis. However, cisplatin’s clinical use as
mono-chemotherapeutic agent suffers limitations due to its nephrotoxicity and adverse side effects
towards normal cells [9,10]. Cisplatin’s efficacy is diminished by the increasing emergence of
resistance that occurs through several ways like decreased drug uptake by cancer cells, drug
detoxification by elevated levels of intracellular glutathiones and increased cellular repair of
cisplatin-damaged DNA [11]. In an attempt to circumvent the single-use drawbacks of cisplatin,
combination therapy with other anticancer drugs has been widely applied for enhancing the
anticancer efficacy and limiting cisplatin’s therapeutic dose while decreasing the toxic side effects
and overcoming the induced drug resistance [12]. This concept of combination therapy, also
known as cocktail therapy, is considered the cornerstone in cancer treatment [13]. Some reported
successful combinations include synergistic treatment of cisplatin with anticancer drugs as
doxorubicin [14], gemcitabine [15] and paclitaxel [16]. Other efficient cisplatin combinations were
reported with antitumor compounds of natural origin as triptolide [6], osthole [17], quercetin [18]
and curcumin [19]. Moreover, caffeine, although itself does not possess antiproliferative activity,
but has shown to enhance the anticancer properties of cisplatin in combination by inhibiting
essential proteins involved in the repair of cisplatin-DNA induced damage [20]. The same case
was observed with dipyridamole (DPM), a coronary vasodilator, which has proven to
2

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synergistically enhance the cytotoxicity of cisplatin against cisplatin-sensitive human ovarian
carcinoma cells by increasing the cellular uptake of cisplatin in a concentration dependent manner
[21].
Combination of cisplatin with anticancer small molecule heterocyclic compounds is discussed in
the literature [22–25]. From the interesting small molecule heterocyclic scaffolds, 1,3,5-triazines
have been intensely studied for their significant wide range of biological activities, especially their
anticancer properties [26]. Examples of reported 1,3,5-triazines anticancer drugs include;
Altretamine (Hexalen®), I [27], Decitabine (Dacogen®), II [28], and Azacitidine (Vidaza®), III
[29] that are employed in the treatment of ovarian cancer, acute myeloid leukemia (AML) and
myelodysplastic syndrome (MDS), respectively. Also, there are several anticancer 1,3,5-triazines
that have reached phase III clinical trials such as BKM-120, IV [30], ZSTK474, V [31] and
BMCL-200908069-1, VI [32] that proved efficacy against different cancer cell lines (Fig. 1). The
wide interest in the 1,3,5-triazine core has led to synthesis of a large number of derivatives with
promising anticancer activities (Fig. 2, A) [32–36].
Chalcones, on the other hand, are privileged scaffolds known for their promising diverse biological
activities of which the anticancer properties are gaining much attention. The ease of preparation
of chalcones make them an appealing synthetic precursor and pharmacologic scaffold [37]. It is
believed that chalcones exert their anticancer effect as DNA interactive agents by integration
between DNA strands via Van der Waal and π-stacking interactions of the chalcone aromatic ring.
While the α,β-unsaturated carbonyl system provides additional electrostatic hydrogen bond
interactions with DNA bases [38]. Furthermore, chalcones are reported to induce apoptosis in
cancerous cells [39–41]. As a result, many chalcone based compounds have been reported over
the last decade as promising anticancer agents (Fig. 2,B) [38,42–47]. Of interest, chalcone-based
1,3,5-triazines have proved to possess valuable anticancer activities [48] but are seldom discussed
in the scientific literature. Thus, much attention needs to be paid on the design of new and efficient
1,3,5-triazinyl-chalcone hybrids.
NH2
N
NH2
N
N
N
N
O
N
N
N
HO
HO
N
O
N
O
N
N
O
OH OH
OH
Azacitidine, III
Decitabine, II
Altretamine, I
O
N
O
N
O
N
O
OH
O
N
N
CF3
N
N
N
N
N
N
N
N
N
N
N
N
N
N
3
H
O
O
O
N
NH2
F2HC
BKM-120, IV
BMCL-200908069-1, VI
ZSTK474, V