Abstract: Objective To investigate the involvement of NRF2/PI3K signaling pathway in sorafenib resistance with a liver cancer cell line SMMC-7721. Methods A SMMC-7721 drug-resistant cell line SMMC-7721-SR was first established by screening under ascendant concentrations of sorafinib. The cells were then transfected with NRF2 siRNA and treated with 10 μmol/L sorafenib for 48 h. Cells viability was detected by CCK-8 method. Apoptosis was detected by flow cytometry. The protein levels of NRF2, Keap1, ARE, p-PI3K and p-Akt were detected by Western blot. The mRNA levels of NRF2, Keap1, ARE, PI3K and Akt gene expression were detected by Real-Time quantitative PCR. Results Sorafenib significantly reduced the survival rate and promoted the apoptosis of SMMC-7721 cells (P<0.05). The promoting effect of Sorafenib on the cells apoptosis was more significant in SMMC-7721 cells when compared to the SMMC-77211-SR cells (P<0.05). The expression of NRF2 mRNA and protein in SMMC-7721-SR cells was significantly higher than that in SMMC-7721 cells, and the levels of Keap1, ARE, p-PI3K and p-Akt protein were significantly higher in SMMC-7721-SR cells (P<0.05). Sorafenib significantly upregulated NRF2 protein and mRNA expression in SMMC-7721 cells (P<0.05). After inhibiting the expression of NRF2 mRNA by specific siRNA, the survival rate of SMMC-7721-SR cells was significantly decreased, and the apoptosis rate was significantly increased, accompanied by decreases in the levels of Keap1, ARE, p-PI3K and p-Akt protein and mRNA expression in the cells after sorafenib treatment (P<0.05). Conclusion Sorafenib induces drug resistance in SMMC-7721 cells via activating NRF2. Inhibition of NRF2 may reverse the sorafenib resistance in SMMC-7721 cells.

Key words: NRF2/PI3K, Liver cancer, SMMC-7721, Sorafenib, Drug resistance