Evaluation of Anti-cancer Effect of Carotenoids Produced by A Halophilic Archaeon, Haloarcula Sp. Strain A15 Isolated from Saline Environment of Iran on Breast Cancer Cells

Abstract The halophilic microorganisms living in Extreme environments contain high concentrations of carotenoids with notable medical abilities. We evaluated the anti-cancer activity of carotenoids extracted from native Iranian halophilic microorganisms with the ability to inhibit breast cancer cell line. To begin the study, 40 halophilic strains were cultured and eight strains capable of producing pigmented colonies were chosen from among those cultured strains. In the next step, from among eight strains using MTT assay, one of them capable of reducing cell viability of the breast cancer MCF-7 cell line was chosen as a selective strain. The principal carotenoid was characterized based on the UV-Visible, FT-IR spectroscopic and LC-MASS analyses. Using Real time PCR technique, the expression of genes specific for apoptosis, in the presence or absence of carotenoid was examined. Among all strains, carotenoid extracted from strain A15 showed the strongest cytotoxic effect on breast cancer cell line (IC50 = 0.0625 mg/mL). 16S rRNA analysis indicated that strain A15 showed similarity with Haloarcula hispanica for about 99.5%. According to the results of the analysis, we can estimate that the principal carotenoid extracted form Haloarcula sp. strain A15 was similar to bacterioruberin. Both late and early apoptosis were increased significantly about 10% and 39%, respectively as a result of up-regulation of CASP3, CASP8, BAX genes expression in MCF-7 cell line. In contrast, the expression of genes MKI67, SOX2 were significantly down-regulated in treated MCF-7 cell line. Halophilic archaeon strain could be a good option to produce high added-value bacterioruberin due to its possible anti-cancer properties.