Page 156 - SRPSKO DRUŠTVO ISTRAŽIVAČA RAKA

Serbian Association for Cancer Research SDIRSACR

framework of a quantitative structure-activity relationship (QSAR) approach. To put QSAR into practice, the ZINC15
database was screened with extended scaffolds that were designed to correspond to the application range of the
model. The screened structures were ranked based on the QSAR prediction and evaluated against VEGFR-2 enzyme.
Results and conclusion: The resulting QSAR allowed for the analysis of the structure-activity relationship of the
compounds. One of several experimentally tested compounds showed high activity at the sub-micromolar level in
inhibiting VEGFR-2, with IC50= 0.497±0.04 μM. The anticancer activity of this compound was evaluated against several
glioblastoma cell lines. The selected compound was active against H4 and A172 cancer cell lines with EC50=16.3 μM
and EC50=23.3 μM, respectively. Its toxicity profile in non-cancerous cells was low. After biological evaluation, it can
be concluded that discovered molecule, with unique structural configuration, can be used as lead molecule to design
new, potent, and effective VEGFR-2 inhibitors. Further testing of similar molecules in glioblastoma cell lines should be
continued.

Acknowledgments and funding: This research was funded by Estonian Research Council grants number MOBJD1101
and number PRG1509.

P65

Copper(II) complexes of indolobenzazepine-derived ligands with kinase inhibitory potential: mechanism
of cytotoxic action in colorectal tumor cells

Irina Kuznetcova , Nevenka Gligorijević , Vladimir B. Arion , Sandra Aranđelović 1
2
1
2
1Institute for Oncology and Radiology of Serbia, Department of Experimental Oncology, Pharmacology Laboratory,Belgrade,
Serbia
2Institute of Inorganic Chemistry of the University of Vienna, Vienna, Austria

Keywords: Antineoplastic agents, copper complexes, indolobenzazepine ligands, colorectal carcinoma hct 116 cells,
mtt assay, cell cycle, kinase inhibition

Background: Following the approval of cisplatin (CDDP) as anticancer drug, research into metallotherapeutics has
expanded, aiming to develop metal-based drugs with improved efficacy and reduced toxicity. The chemical diversity of
metal based complexes enables the development of hybrid drugs with bioactive ligands that may overcome limitations
of traditional treatments, exploiting mechanisms beyond DNA binding, such as enzyme inhibition, redox modulation,
and interference with cancer signaling. This study explores a new class of ligands structurally related to paullones, which
exhibit CDK kinase inhibitory activity. Series of eight novel ligands with an indolobenzazepine core were synthesized
and complexed with copper(II) to improve pharmacological properties.
Material and Methods: The biological evaluation in vitro included tests for antiproliferative activity, cell cycle effects,
kinase inhibition and apoptosis induction, with cisplatin as a reference.
Results and Conclusions: MTT assays in a panel of human tumor cell lines showed that metal-free ligand HL8 and
Cu(II) complexes 4 and 8 exhibited the highest cytotoxic activities against colorectal carcinoma HCT 116 cells, with IC50
values in the sub micromolar range (0.8–0.9 µM). A structure-activity relationship analysis suggested that the presence
of a methyl substituent at the Schiff base C=N group contributes to the potency of ligand HL8 in HCT 116 cells, an effect
maintained in complex 8 (IC50 = 0.8 μM), while in non-tumor MRC-5 cells IC50 = 1.7 μM. Copper coordination also
enhanced the activity of HL4 (IC50 =2.03) yielding complex 4 with an improved IC50 of 0.71 µM. Further mechanistic
studies including cell cycle analysis revealed that HL4 and complex 4 caused mainly G2/M arrest and increased Sub-G1
apoptotic population. Complex 8 induced a certain Sub-G1 peak, while HL8 led to concentration-dependent cell
accumulation in G1 phase (after 24 h), suggesting inhibition of key mediators of G1 phase progression. Kinase inhibition
test confirmed strong inhibitory potency of HL8. Annexin V-FITC apoptosis assay revealed the pro-apoptotic effects
of complexes 8, HL8, and HL4. Morphological studies showed reduced cell confluency and the presence of rounded,
irregular cells in a time- and dose-dependent manner, further supporting apoptosis as the main mechanism of cell
death. Indolobenzazepines HL4 and HL8 represent promising structures for further development of metal complexes
with multi targeted mode of action.

Acknowledgments and funding This work was supported by the Austrian Science Fund (FWF) via grant number
P31293-N37, and by the Ministry of Science, Technological Development and Innovation of the Republic of Serbia
(grant numbers: 451-03-66/2024-03/200043 and 451-03-136/2025-3/200043).

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