Influence Of Hypoxia On Proliferation And Invasion, And On Expression Of The Associated Gene HIF-1α And E-cadherin In Human Colorectal Cancer Cell Lines SW480in Vitro

[Objectives]To explore the influence on the biological behaviors of human colorectal cancer cell under hypoxia conditions, both the expression of HIF-1α(the gene associated to hypoxia) and E-cadherin(the related gene to EMT) was detected in human colorectal cancer cell lines SW480, as well as the tumor cell proliferation activity and invasive capacity in vitro was examined under hypoxia conditions simulated by CoC12. We purpose to diseuss its contribution in development of Colorectal carcinoma and raise morphology foundation for clinia study of Colorectal carcinoma..[Methods]Simulated hypoxia environment was chemically formed by CoC12in different concentrations. SW480cells were divided into three groups:normoxic group, hypoxic group and anaerobic group.The proliferation of SW480cell lines was observed by MTT assay, while the invasion by Transwell chamber. The expression sites of HIF-1α and E-cadherin were detected by immunocytochemistry. The expression levels of HIF-1α and E-cadherin in mRNA and protein were measured respectively by reverse transcription-polymerase chain reaction (RT-PCR) and Western-blotting assay.[Results]The results are as the followings:1. The growth of SW480cell lines was significant inhibited in all of the hypoxia manners, and the cells growth gradually declined along with the development of hypoxic extent. The difference between the normoxic and the hypoxic or the anaerobic showed statistical significance (P<0.01), and so did that between the hypoxic and the anaerobic.2. Contrasted with the growth, the invasiveness of the normoxia, the hypoxia and the anaerobic inversely increased in turn.3. At high magnification, the expression site of HIF-la protein was mainly in nuclei and cytoplasm,whereas E-cadherin in cytomembrane and cytoplasm.The locations were not changed by all of the hypoxia manners. With the increase of hypoxia levels, the expression levels of HIF-la did rise gradually, whereas E-cadherin descended by degrees.4. By RT-PCR assay, HIF-1α mRNA expression in from group normoxia to hypoxia to anaerobism increased along with the increase of CoCl2concentrations,while E-cadherin mRNA expression in the corresponding groups inversely decreased in turn. Similar expression results were observed by Western-blotting assay for protein of HIF-1α and E-cadherin. Abnormal expression of HIF-1α and E-cadherin are closely associated with proliferation and migration in CRC cell SW480. It suggests that HIF-1α can be treated as the target in further study of targeted therapy and E-cadherin expressions can serve as important molecular signals for judgment of malignant potency of CRC.[Conclusion]1. Hypoxia enhances the invasiveness of SW-480cells in vitro, but reduces their proliferation capacity.2. Hypoxia up-regulates expression of HIF-1α in gene and protein,but down-regulates that of E-cadherin.3. The expressions HIF-la and E-cadherin were negatively correlated, and showed a good uniformity by mRNA and protein assays(r=-0.85,P<0.01; r=-0.97,P<0.01; respectively).