The mechanistic action of Silver(I) thiocyanate 4-methoxyphenyl phosphine promoting apoptosis in MCF-7 and MDA-MB-231 breast cancer cell lines
Breast cancer is at the forefront of the most frequently diagnosed cancer globally. The available multidisciplinary treatments succumb to adverse toxicity and drug resistance. Anti- cancer metallodrugs with apoptosis potential have been adopted in systemic cancer therapeutics. The quest for effective metal coordination complexes with improved pharmacological profiles are on the rise in the current cancer metallotherapy era. Herein, we aim to report the apoptosis-inducing potential and mechanistic action of UJ3 on in vitro MCF- 7 and MDA-MB-231 breast cancer cell lines. A cytotoxicity assessment involving dose- response and viability studies was undertaken to evaluate the pharmacological profile of UJ3. In the MCF-7, UJ3 operated as a pharmacological anti-cancer agent, exhibiting malignant selectivity and sustained potency. In the MDA-MB-231, UJ3 proved selective and cytotoxic; however, cell recovery impeded the drugs profile. The Annexin V and 7-AAD assay, MitoPotential assay, oxidative stress assay, MitoTracker Orange dye and Hoechst 33258 dye were used to determine the cell death modality. UJ3 elicited mitochondrial-mediated apoptosis in both malignant cell lines, made evident via reduced mitochondrial membrane potential, disrupted bioenergetics, phosphatidylserine exposure, oxidative stress, cellular morphology and nuclear apoptotic morphology. Pro-apoptotic caspases and poly-(ADP-ribose) polymerase (PARP) were studied via western blots to gain insight into the apoptosis pathway. In the MCF-7, UJ3 activated the intrinsic apoptosis pathway via cytochrome c expulsion, caspase-7 activity and PARP cleavage. In the MDA-MB-231, UJ3 activated a caspase- independent cell death pathway which led to the study of the apoptosis-inducing factor (AIF) via fluorescent tracking. UJ3 induced an AIF-mediated apoptosis pathway in MDA-MB-231. This study highlights UJ3 as an apoptosis-inducing agent that executes selective malignant death via mitochondrial targeting in MCF-7 and MDA-MB-231 cell lines. UJ3 demonstrates promising activity in MCF-7 cells that warrant further investigation. Future studies are required to further clarify and validate UJ3s mechanistic action.
A dissertation submitted in fulfilment of the requirements for the degree of Master of Science to the Faculty of Science, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, 2022