The Influence Of Hypoxia Inducible Factor 2 Alpha On The Biological Behaviour Of Hepatocellular Carcinoma Cells

The aims of this article were to study the expression of hypoxia inducible factor-2 alpha in the hepatoma tissue, and the influence of mionectic culture on the expression of hypoxia inducible factor-2 alpha, and another, the influence of hypoxia inducible factor-2 alpha on the proliferative and invasive abilities of hepatocellular carcinoma cells. To explore primarily the significance of hypoxia inducible factor-2 alpha in the hepatocellular carcinoma cells.PART ONE Expression of HIF-1α and HIF-2α in Hepatoma CellsObjectives: The constructions and functions of hypoxia inducible factor-2 alpha (HIF-2α) and hypoxia inducible factor-1 alpha (HIF-1 α) are resemble, but they can not be replaced by each other. The expressions of them disaccord. This article is to examine the differential expression of hypoxia inducible factor-2 alpha (HIF-2α) and hypoxia inducible factor-1 alpha (HIF-1α) in SMMC-7721 hepatoma cells after prolonged hypoxia, and explore the possible regulatory mechanism.Methods: Using 1% mionectic incubator to simulate the anoxic circumstance of SMMC-7721 hepatoma cells, and measure the expressional quantum of mRNA and protein of HIF-1α and HIF-2α, and quantum of mRNA of natural antisense of HIF-1α lpha (aHIF), and meantime measure the half life of HIF-1 and HIF-2α mRNA by CoCl₂ and transcription inhibitor 5,6 -dichlorobenzimidazole-1- beta-d-ribo furanoside (DRB) .Results: Actual hypoxia induces rapidly the accumulation of HIF-1 and HIF-2 α protein in hepatoma cells. With the prolonged hypoxia, the HIF-1 α mRNA drops due to its stability, whereas HIF-2α mRNA and protein and aHIF mRNA increase.Conclusions: In prolonged hypoxia, HIF-2 α may play a more important role than HIF-1α on the metabolic adaption of tumor cells, involving the progress, the invasion and metastasis, and the resistance of chems and radiotharepy of the hepatoma cells. aHIF may participate the regulation of HIF-1α mRNA .PART TWO The Clinical Significance of the HIF-2α Expression in HCCObjectives: To investigate the expressional and clinical meaning of hypoxia inducible factor-2 alpha (HIF-2α) in hepatocellular carcinoma (HCC).Methods: Tumor tissues in 67 cases of HCC were studied by the semi-quantitative reverse transcriptase-polymerase chain reaction(RT-PCR) and immuno-histochemical technique.Results: HIF-2α could be detected in 27 cases (40.3%). For the transcription of HIF-2α mRNA and the expression of HIF-2α protein, there are significant differences between large and small tumors, tumors of spreading type and non-spreading type, and tumors with necrosis and without necrosis. No apparent significant difference was observed between tumor histological grades.Concisions: HIF-2α is expressed in lots of HCC, and its expression is at significant high level in the HCC with large size, with necrosis and being spreading type (P<0.05), which indicates the expression of HIF-2 α is not only responsible for the malignant growth of HCC, but a factor influencing the infiltration and metastasis of HCC (P>0.05).PART THREEThe Effects of HIF-2α on The Proliferation and The Invasion of Hepatocellular Carcinoma CellsObjectives: To study the effects of hypoxia inducible factor-2 α (HIF-2α) on the proliferation , adhesion and the invasion of SMMC-7721 cells under anoxia culture.Methods: Lipofectamine-mediated HIF-2α ODN was transfected into SMMC-7721 cells, and cultured under 37°C, 1%O₂,5%CO₂. Then determine the expression of HIF-2α mRNA and protein to evaluate the effect of transfection. Using MTT to measure the proliferative and adhesive activity of SMMC-7721 cells, and transwell cell culture chambers toexplore the adhensive and invasive activity of SMMC-7721 cells.Results: The expressions of HIF-2α mRNA and protein were inhibited significantly by HIF-2 α ASODN (P<0.01). The blockage of HIF-2 α expression significantly inhibited the adhesive activity (inhibition ratio 16. 99%—31.07%, P<0.01) and invasive activity (inhibition ratio 17.9%, P<0.01), while had no significant influence on the proliferative activity of SMMC-7721 cells (P>0.05).Conclusions: The blockage of HIF-2 α expression inhibits the adhesive and invasive activities of SMMC-7721cells, and has no impact on their proliferation.