الملخص الإنجليزي
Background: Marine environment is a natural reservoir for different products, some of which have been tried for the treatment of different diseases including cancer where apoptosis was induced for the killing of cancer cells. Corals have many potential secondary metabolites such as sesquiterpenoids, diterpenes and sterols that exhibit cytotoxicity on cancer cells. Thus, the major interest in testing corals against cancer cells to discover curative, effective and tumor-specific chemopreventive agents. Aim: This study aimed to screen coral extracts from two different species (Sarcophyton sp. and Acanthogorgia sp.) collected from Bandar Al-Khayran area (Muscat, Sultanate of Oman) for their cytotoxicity against breast cancer cells (MCF-7) and to explore the cellular apoptotic pathways induced by these natural products. Methods: MTT assay was performed to test the cytotoxicity and determine the IC50 - a concentration at which 50% of the cells are killed. Also, Hoechst stain was used to confirm apoptosis induction and assess the morphological change of nuclei. Moreover, qRT-PCR and western blot analyses were used to examine the expression of the genes and proteins associated with apoptosis, respectively. Results: The IC50 for Sarcophyton sp. and Acanthogorgia sp. was determined to be 97.46 (ug/ml) and 385.2 (ug/mL), respectively. Hoechst staining revealed pyknotic and fragmented nuclei compared to the untreated cell. Sarcophyton sp.- induced apoptosis involved an increase in caspase-3. Moreover, an increase in the expression of p53 proteins was observed in MCF-7 cells treated with Acanthogorgia sp. Crude extract. Conclusion: The two corals used in this study induced apoptosis in the cancer cell line MCF-7 as indicated by nuclear condensation, fragmentation and the increased expression of caspase-3 and p53 proteins. Although, the chemical properties of these two corals are not studied yet, this study clearly shows an apoptotic induction in treated cells. This present investigations could be considered as a pilot study, and purification of the extracts as well as the use of appropriate normal cells would most likely improve the effectiveness of theses natural products on cancer cells.