Fundamental Studies On The Effect Of Antisense HIF-1α Gene Transfection In Improving The Radiosensitivity Of Oral Cancer

Hypoxia inducible factor-1α, as an oxygen-dependent regulation transcription cell factor and regulates less than 100 putative target genes, is a master regulator of the transcription of many different factors involved in the biological progress of hypoxia malignant tumors. HIF-la is a vital important biomarker of malignant tumor prognosis and helps reduce tumor radiosensitivity. The purpose of this study was to investigate the expression of HIF-1α in oral cancer and its clinical and prognosis signification, to evaluate the radiobiological response in vitro of human oral cancer cell line TCa8113 and BCaCD885. Furthermore, we try to investigate the effect of in vitro transfection of antisense HIF-la oligonucleotides under normoxic condition on the radiosensitivity of the two tumor cell lines. 1. LsAB immunohistochemistry staining was applied in this study to evaluate the expression levels of HIF-1α and CD34 in oral cancers. The relationship within HIF-1α expression, clinical pathologicalfactors and tumor prognosis were investigated. 2. MTT assay was employed to detect the survival fraction of the two oral cancer cell lines after different dose of 192Ir high dose rate γ ray brachytherapy. The survival curves were synthesized according to the MTT results via Sigma Plot 8.0, and some of the main radiobiological parameters were determined by statistic program. The morphological and ultrastructure changes of the two cell lines after brachytherapy were also observed through both optical microscope and transmission electron microscope. 3. Antisense HIF-1α oligonucleotides were transfected into TCa8113 and BCaCD885 cells. Changes of the radiobiological reaction of the two cell lines via flow cytometry and MTT assay.The results show that 1. HIF-1α high expression was observed in both tongue and buccal carcinoma specimens. There was no significant relationship between HIF-1α expression and the pathological differentiation, while high expression of HIF-1α was correlated with higher microvessels density, the clinical stages and tumor prognosis. 2. Both TCa8113 and BCaCD885 cells showed low radiosensitivity to 192Ir γ ray, SF2 values of which were 0. 878 and 0. 862 respectively. 3. Antisense HIF-1α oligonucleotides transfection under normoxic condition increased the apoptosis rate to the two cell lines significantly,the SER SF2 values of TCa8113 and BCaCD885 cells were 1.52 and 1.48 respectively.Based on these findigs, there exists over expression of HIF-1α in oral cancers, which is a vital important biomarker of oral cancer prognosis and helps reduce tumor radiosensitivity. In vitro antisense blocking of the HIF-1α mRNA expression under normoxic condition can significantly improve the radiosensitivity of oral cancer cells and increase the apoptosis rate of oral cancer cells after 192Ir y ray brachytherapy.