Evaluation of anti-tumor effect of the exopolysaccharide from new cold-adapted yeast, Rhodotorula mucilaginosa sp. GUMS16 on chronic myeloid leukemia K562 cell line.

Recently, the development and application of fungal exopolysaccharides (EPS) as natural biopolymers are on the rise. The present study is based on the investigation of possible antiproliferative and antioxidant activities of EPS from the Rhodotorula mucilaginosa sp. GUMS16 on BCR-ABL positive cells (K562). The cytotoxicity, colony formation assays lactate and dehydrogenase (LDH) activity were performed to assess the possible cancer cell death. To elucidate the underlying antiproliferative mechanism of the EPS, cell cycle analysis following real-time PCR (gene expression assessment) were evaluated. The results indicated that, the EPS with an IC50 dose of 1500 μg/ml, reduced the viability of K562 cells without having toxic effects on normal cells as well as decrease in size and number of colonies in EPS-treated group (p < 0.0001). The increase of LDH was 2.75 times more than the control (p < 0.0001). Gene expression revealed up- and down-regulation of apoptotic and anti-apoptotic genes in EPS group compared with the control. Moreover, the DPPH scavenging activity of the EPS in treated cells was significantly higher than the control group (p < 0.0001). Taken together, we concluded that the EPS from GUMS16 strain is able to inhibit the growth of K562 cells besides having antioxidant activities.