Hypoxia Induced Pemetrexed Resistance In Human Non-small Cell Lung Cancer Via Hypoxia-inducible Factor 1α

Purpose: We have proved hypoxia conditions are connected with the occurrence and development of chemoresistance closely. Hypoxia inducible factor-1(HIF-1) is a critical transcription factor. Pemetrexed is the new chemotherapy drugs for non-small cell lung cancer treatment, but also exists chemoresistance. Our experiment study the mechanism of hypoxia induced pemetrexed resistance in human non-small cell lung cancer via hypoxia-inducible factor 1α.Methods: The A549 NSCLC cells are cultured in hypoxic conditions .the sensitivity of the cells to Pemetrexed and the cell inhibitory rate were determined by MTT assay. The expression and the transcriptional activity of HIF-1αwere examined by western blot.The cell cycle distribution was analyzed by the flow cytometry. In addition, we silence HIF-1αexpression via performing RNA interference.Results: (1) The MTT assay demonstrates that hypoxia substantially reduces the susceptibility of non-small cell lung cancer cells to pemetrexed.(2) Building HIF-1α/siRNA model, knockdown of endogenous HIF-1αto prove the function of HIF-1 in hypoxia cells. Westernblot testing suggests under the hypoxia condition HIF-1αis significantly overexpressed .HIF-1α/siRNA can significantly reduce the expression of HIF-1α.(3) The MTT assay of silencing HIF-1αby siRNA shows that the inhibiting rates of A549 cell to pemetrexed increases. There are no differences between hypoxic and normoxic conditions.(4) Cell cycle analysis suggests that hypoxia promote G0/G1 arrest and silencing HIF-1αby siRNA switches G0/G1 arrest into the cell cycle, cell cycle arrest at the S phase increases, ultimately, recovers the responsivity of A549 cells to pemetrexed.Conclusion: Our experiment proves that hypoxia-inducible - 1 alpha via hypoxia causes non-small cell lung cancer in G0 / G1 arrest, and causes the chemoresistance to pemetrexed that acts on S phase. Eliminating anoxic conditions or silencing endogenous HIF-1 by RNA interference might provide a novel method to enhance effectiveness of pemetrexed in the treatment of human lung and other tumors.