Overexpression of AQP9 inhibits the proliferation of human hepatocarcinoma SMMC-7721 and Huh-7 cells in hypoxic microenvironment / 肿瘤

ABSTRACT

Objective: To investigate the aquaporin 9 (AQP9) involved in the hypoxia response of hepatocellular carcinoma cells in hypoxic microenvironment, and to explore its possible mechanism. Methods: The hypoxia model of hepatocellular carcinoma SMMC-7721 and Huh-7 cells was constructed by using hypoxia incubator. The expression of AQP9 mRNA in SMMC-7721 and Huh-7 cells and the expression of AQP9 protein in Huh-7 cells after hypoxic incubation were detected by real-time fluorescent quantitative PCR and Western blotting, respectively. After SMMC-7721 and Huh-7 cells were infected with recombinant lentivirus LV-AQP9 with AQP9 over-expression or empty vector lentivirus LV-PWPI, the SMMC-7721-AQP9 and Huh-7-AQP9 cells with stable over-expression of AQP9 as well as the negative control SMMC-7721-PWPI and Huh-7-PWPI cells were established. The proliferation and the expressions of hypoxia-inducible factor-1α (HIF-1α), mammalian target of rapamycin (mTOR) and phosphorylated mTOR (p-mTOR) in SMMC-7721-AQP9, SMMC-7721-PWPI, Huh-7-AQP9 and Huh-7-PWPI cells after hypoxic incubation were detected by CCK-8 assay and Western blotting, respectively. Results: In hypoxic microenvironment, the expression levels of AQP9 mRNA and protein in Huh-7 cells were decreased (both P < 0.05), and the expression level of AQP9 mRNA in SMMC-7721 cells was decreased (P < 0.05). As compared with normoxic microenvironment, the inhibitory effect of over-expression of AQP9 on the proliferation of SMMC-7721 and Huh-7 cells was stronger in hypoxic microenvironment (both P < 0.05). The expression levels of HIF-1α and p-mTOR proteins in SMMC-7721-AQP9 and Huh-7-AQP9 cells after hypoxic incubation were significantly lower than those in the SMMC-7721-PWPI and Huh-7-PWPI cells (all P < 0.05). Conclusion: In hypoxic microenvironment, the over-expression of AQP9 may inhibit the proliferation of SMMC-7721 and Huh-7 cells by down-regulating the expression of HIF-1α, and this inhibitory effect is stronger than in normoxic microenvironment.