Effect of all -trans retinoic acid on differentiation of liver cancer stem cells

Abstract

Objective To investigate the differentiation effect of All-trans retinoic acid (ATRA) treating CD133+ liver cancer stem cells. Methods ATRA was added into the stem cell culture medium at different concentrations (1×10-9-1×10-5 mol/L). After cultured for 5 days, the expression of CD133 antigen was detected by flow cytometry. The expressions of sex determining region Y box 2 (Sox2), Octamer-binding transcription factor 4 (Oct4), Nanog mRNA and protein were detcted by quantitative polymerase chain reaction (qPCR) and Western blotting. The cell proliferations in different groups were tested using methyl thiazol tetrazolium (MTT) assay. Results The percentage of HepG2/CD133+ cells decreased with the increase of ATRA concentration from (90.81±0.48)% to (90.23±0.37)%, (89.77±0.41)%, (88.65±0.29)%, (84.92±0.35)% and (79.6±0.27)%, respectively. The level of Oct4 mRNA in the 1×10-6 mol/L ATRA group was significantly lower than that in the blank control group (P=0.037), and there was no significant difference between the Sox2 and Nanog groups (P=0.067, 0.229). The protein expression levels of all the three markers decreased, and Sox2 and Nanog were significantly decreased. Cell proliferation activity increased slightly at 1, 2, 3, 5 d, but did not show significant increase (P=0.562, 0.318, 0.863, 0.444). Conclusion Liver cancer stem cells had significantly reduced stem cell characteristics after ATRA treatment. ATRA induces differentiation of liver cancer stem cells at different concentrations within a certain concentration range. The higher the concentration, the stronger the differentiation. Key words: Neoplastic stem cells; Tretinoin; Differentiation