[Hypoxia-inducible factor-1 alpha dependent expression and significance of the related multidrug resistance genes induced by hypoxia in human hepatocarcinoma cell].

Objective: To explore the mechanism of multidrug resistance of hepatocellular carcinoma induced by hypoxia and the potential role of hypoxia-inducible factor-1 alpha (HIF-1 alpha) and multidrug resistance related genes.
Methods: Human hepatocarcinoma cell lines HepG2 cells were exposed to hypoxia and were transfected by plasmid HIF-1 alpha/PCDNA3, respectively. The expressions of multidrug resistance gene (mdr1), multidrug resistance protein (MRP1), and lung resistance protein (LRP) gene at the mRNA and the protein levels in the above two groups were respectively analyzed by real-time fluorescent quantitative PCR and Western-blot technique.
Results: In the hypoxia group, the expressions of mdr1, MRP1 and LRP were stepped up correlating to the degree of hypoxia, especially the prominent increase in the expression of MRP1. Furthermore, they were synchronous with the changes of the expression of HIF-1 alpha. Also the increased expression of mdr1, MRP1, and LRP gene was observed in transfected HepG2 cells by plasmid HIF-1 alpha/PCDNA3.
Conclusions: Resistance of hepatocellular carcinoma to chemotherapeutics could be induced by hypoxia. HIF-1 alpha may be critical to the upregulation of the expression of the related multidrug resistance genes induced by hypoxia. HIF-1 alpha and these related multidrug resistance genes could be potential molecular targets for reversing multidrug resistance of hepatocellular carcinoma.