الملخص الإنجليزي
Epithelial Ovarian Cancer (EOC) is the 8th most common cause of death from cancer in
women worldwide. The disease is characterized by advanced presentation, multiple
relapses, resistance to treatment, and ultimately poor prognosis. Thus, there is an urgent
need to support research to identify effective drugs that may have cytotoxic properties
and may help overcome the resistance to frontline chemotherapy. Such compounds may
be obtained from natural resources. Oman's extensive coastline may contain marine
species from which bioactive natural chemicals can be harvested. In a previous study, 40
Omani marine compounds were screened for the anti-cancer activity using the MCF-7
breast cancer cell line. Five compounds, including MalforminA1 (MA1),
Hymenialdisine, and Sarcophyton sp. extracts, were found to have significant anti-cancer
activity. Objective: The present study aimed to test these compounds' anti-cancer activity
and potential on cisplatin-sensitive (A2780S) and cisplatin-resistant (A2780CP) ovarian
cancer cell lines. In addition to choose one compound with maximum activity and study
whether this compound will help overcome resistance to cisplatin. In addition, we sought
to study this compound's putative mechanism of cytoxicity. Results: Using AlamarBlue
and Cell Counting Kit (CCK8) assay, our results revealed that MalforminA1 exhibited
the highest cytotoxicity on A2780S and A2780CP cell lines with IC50 values of 0.23µM
and 0.34µM respectively, whereas 10Z-hymenialdisine exhibited a very low cytotoxic
effect. Both the DNA fragmentation test and Flow cytometry analysis confirmed the
cytotoxic effect of MA1 and the synergism of MA1 and cisplatin. Several key genes and
proteins were examined using RT-qPCR, western blot, and immunofluorescence
techniques to investigate the mechanisms of cell death induced by MA1 in ovarian cancer
cells. The results suggest that in addition to apoptosis, there are other pathways that MA1
follows to kill ovarian cancer cells. A significant reduction in the pro-apoptotic genes
BAD, BAX, FADD, TRADD, and RIP1, and a significant increase in the expression of
γ-H2AX and caspase1, activation of NF-Kβ following the treatment indicates that MA1
causes DNA damage in inflammatory-related programmed cellular death. Moreover, the
data suggest the involvement of the autophagy cellular death pathway as seen by the
conversion of LC3B-I protein to the lipidated protein LC3B-II after MA1 treatment.
Furthermore, MA1 was found to suppress several vital biological process-related genes
like Yap/Taz, Stat3, and Akt, as well as to affect the cell dynamics by suppressing cellular
cytoskeleton-related genes such as α-Tubulin, β-Tubulin, Vimentin, β-actin, GAPDH,
Beta-catenin. Conclusion: MA1 induces significant cytotoxicity at very low
concentrations and overcomes resistance to cisplatin in cisplatin-resistant cell lines.
Further investigations are required to fully elucidate the mechanism of action of
cytotoxicity.
