alpha1,2-fucosyl transferase gene, the key enzyme of Lewis y synthesis, promotes Taxol resistance of ovarian carcinoma through apoptosis-related proteins

Fei-Fei Li, Dan Sha, Xiao-Yan Qin,  Chang-Zhong Li,  Bei Lin

Abstract:

We aimed to investigate the role of FUT1 gene in Taxol resistance and to explore its mechanism in epithelial ovarian cancer. Three ovarian cancer cell lines, ES-2, SK-OV-3 and OVCAR-3 were selected from epithelial ovarian cancer in this experiment. Western blot was used to validate the protein expression level of FUT1 and the apoptosis proteins. The expression level of the corresponding carrier was validated by RT-PCR. Transfection and isolation of stable transfectants were carried out to establish the cell line models. The different concentrations of Taxol on the inhibition of cell growth rate was measured by MTT, in which Taxol resistance profiling in ovarian cancer cells was determined by IC50 data. Flow cytometry was conducted to compare cell apoptosis ability. Caspase-3 activity and the apoptosis proteins were measured by colorimetry and western blot, respectively, to further compare the cell apoptosis ability in different groups. To demonstrate the inhibition of miR-FUT1 combined with Taxol therapy against ovarian cancer, xenograft assay was carried out for the in vivo effect. The western blot results indicate that FUT1 is expressed in all of the ovarian cancer cells with different expression level: ES-2 ˃ SK-OV-3 ˃ OVCAR-3. Besides, FUT1 siRNA was used in the maximum expression of FUT1 cell line ES-2, or over-expression plasmid was used in the minimum expression of FUT1 cell line OVCAR-3, to establish stable expression cell lines. After the treatment with Taxol, the inhibition rate of Taxol was obviously decreased with the established cell model above, and the IC50 level was significantly increased in the FUT1 over-expression + Taxol group (P<0.05, respectively). Additionally, after the treatment with Taxol, the results of flow cytometry demonstrated that the apoptosis rate was increased or decreased obviously in the FUT1 low or high expression group compared with the control group (P<0.05, respectively). Furthermore, the results of western blot indicated that the expression of the anti-apoptotic proteins such as survivin, XIAP, BCL-2 and BCL-xL was significantly decreased or increased in the FUT1 low or high expression group compared with the control group (P<0.05, respectively), and the determination of pro-apoptotic protein caspase-3 enzyme activity test demonstrated that the caspase-3 enzyme activity was increased or decreased obviously in the FUT1 low or high expression group compared with the control group (P<0.05, respectively). Finally, we verified the inhibition effect of siRNA-FUT1 combined with Taxol therapy against ovarian cancer through xenograft assay in vivo. Our results suggest that FUT1 combined with Taxol could promote Taxol resistance and inhibit cell apoptosis by raising the expression of anti-apoptotic proteins such as survivin, XIAP, BCL-2, and BCL and inhibiting caspase-3 enzyme activity. Thus, FUT1 might serve as a therapeutic target for ovarian cancer.