Effects Of Hypoxia On Apoptosis And Proliferation Of Rat Hepatocellular Carcinoma Cell Line CBRH7919 Induced By Cobalt Dichloride

Objective: Hypoxia is a common phenomenon in solid tumors. Thekey regulator of the hypoxia response is the hypoxia inducible factor1(HIF-1). HIF-1 is a vital transcription regulating factor and is involvedin tumor angiogenesis, tumor growth, metastasis and apoptosis. Thisproject was designed to investigate the apoptosis and proliferation ofhepatocellular carcinoma cell induced by hypoxia, and to study the role ofHIF-1αin the induction course.Methods: Rat hepatocellular carcinoma cell line CBRH7919 wastreated with different concentrations of CoCl₂ for different times: 100μM,200μM, 300μM and 400μM for 24, 48, 72 and 96 hours, respectively.MTT assay was used to measure the anti-proliferating effect of CoCl₂.Then CBRH7919 cells were treated with 300μM of CoCl₂ for 0, 4 and 24hours. The expression of HIF-1αat the levels of transcription andtranslation were detected by RT-PCR and immunocytochemistry. Thechange of cell cycle, membrane potential of mitochondria and apoptoticratio were detected by flow cytometry or fluorescence microscopy.Results: 1. MTT assay showed COCl₂ could inhibit CBRH7919 cells ina dose- and time- dependent manner. 2. HIF-1αis upregulated both at thetranscriptional and translational levels under hypoxic condition. 3.CBRH7919 cells appeared notable apoptosis aider incubated with 300μMCoCl₂ for 24 hours or more, apoptotic ratio of CBRH7919 cells were 2.31±1.1%,5.62±2.4%,21.2±7.5%, respectively. There were also adecrease in the mitochondrial membrane potential and cell cycle arrest atG₀/G₁ phase.Conclusion: CoCl₂ can induce apoptosis of rat hepatocellular cell lineCBRH7919. HIF-1αplays an important role in this hypoxia-inducedapoptosis, which supplys a further theoretical foundation to theanti-cancer use of HIF-1α.