Page 111 - SRPSKO DRUŠTVO ISTRAŽIVAČA RAKA

SDIRSACR Oncology Insights

In this study, we aimed to investigate the effect of both pharmacological and genetic inhibition of PDK1 on human
breast cancer cell proliferation and viability.
Methods: Three breast cancer cell lines (MCF7, SK-BR-3 and MDA-MB-231) were screened using four small-molecule
PDK1 inhibitors (GSK2334470, BX-517, BX-912, and PDK1- IN-RS2) via SRB cytotoxicity assay. The triple-negative MDA-
MB-231 cell line was selected for further experiments. The most active inhibitor was then tested in wound healing
(scratch) assay and cell viability assay in order to investigate its anti-migratory and anti-proliferative capacity. Flow
cytometry was performed to examine the inhibitor’s effect on the cell cycle of asynchronous MDA-MB-231 cells,
while siRNA-mediated silencing of PDK1 was used to compare pharmacological versus genetic inhibition of the kinase.
Western blotting was used to evaluate the expression of apoptotic markers, including caspases, in PDK1-silenced MDA-
MB-231 cells.
Results: Among all tested inhibitors, BX-912 exhibited dose- and time-dependent suppression of proliferation and
migration of MDA-MB-231 cells without inducing notable cytotoxicity, suggesting a cytostatic effect. In contrast,
silencing of PDK1 using specific siRNA induced significant cell death at both 24 and 48 hours post-transfection, partially
through apoptotic pathways, suggesting that additional mechanisms of cell death may also be involved.
Conclusions: Our results suggest that while pharmacological inhibition of PDK1 suppresses growth and migration in
breast cancer cells, genetic silencing using siRNA leads to a stronger and more profound cytotoxic effect. This highlights
both the importance of the role of PDK1 in the survival of Triple Negative Breast cancer cells and the need for more
selective and potent PDK1 inhibitors. Further experiments are underway to investigate the role and therapeutic
potential of PDK1 inhibition in breast cancer.

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Sigma receptor 2 ligand Siramesine: Unraveling its role in angiogenesis

Sima Kilic , Ayca Uvez ,Elif Ilkay Armutak , Konstantinos Dimas 3
1
2
2
1 Institute of Nanotechnology and Biotechnology, Department of Biotechnology Istanbul University – Cerrahpaşa, Istanbul, Turkey
2Department of Histology and Embryology, Faculty of Veterinary Medicine, Istanbul University- Cerrahpasa, Istanbul, Turkey
3Department of Pharmacology, Faculty of Medicine, University of Thessaly, Larissa, Greece

Keywords: angiogenesis, siramisine, σ2 receptor ligand, CAM assay, anti-angiogenic effect

Background: Siramesine is a selective σ2 receptor ligand that has demonstrated potent antiproliferative properties;
however, its role in angiogenesis remains unexplored. This study investigated the antiangiogenic and anticancer
potential of siramesine using in vitro, ex vivo, and in vivo models.
Methods: The cytotoxic effect of siramesine on endothelial cells (EA.hy926) was examined with the SRB assay. Molecular
markers of angiogenesis and survival pathways were also examined using Western blotting. The anti-angiogenic activity
of siramesine was evaluated by an in vitro tube formation assay, an ex-vivo aortic ring assay, and in vivo chick embryo
chorioallantoic membrane (CAM) and Matrigel plug assay.
Results: Cytotoxicity assays (SRB) revealed dose- and time-dependent suppression of endothelial cell viability in HUVEC
and EA.hy926 cell lines. Functional assays, including tube formation, wound healing, colony formation and aortic ring
assays, demonstrated that siramesine significantly inhibited angiogenic activity and cellular migration. Western blot
analysis showed that siramesine modulates angiogenesis-related pathways by downregulating PGRMC1 and altering
AKT and ERK1/2 signaling in both endothelial cells and PDAC xenograft tissues. Additionally, siramesine induced G1 cell
cycle arrest, as evidenced by FACS analysis. In vivo validation via CAM and Matrigel plug assays confirmed the presence
of strong antiangiogenic effects.
Conclusions: Taken together, these findings suggest that siramesine exerts potent anti-angiogenic and anti-tumour
effects by modulating survival and proliferation pathways, thus supporting its potential as a novel therapeutic candidate
in PDAC. Further mechanistic studies are required to elucidate its precise mode of action.

Acknowledgments and funding: This study was funded by the TUBITAK 2219 International Post Doctoral Research
Fellowship Programme.

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