【作者】 韩波；

【导师】 李龙江；

【作者基本信息】 四川大学 ， 口腔临床医学， 2005， 博士

【摘要】 氧依赖性转录活化细胞因子低氧诱导因子-1α（Hypoxia inducible factor-1α,HIF-1α）在恶性肿瘤普遍存在的低氧微环境中处于重要的中枢调节地位,其调控的下游靶基因近百种,除涉及肿瘤生长、发展、侵袭、肿瘤细胞凋亡、血管生成外,还导致肿瘤细胞对放化疗的抵抗,其表达水平对恶性肿瘤的放射治疗敏感性与预后具有重要的影响。 本研究拟通过免疫组化染色了解HIF-1α在人口腔癌中的表达及其与口腔癌微血管密度之间的关系,探讨口腔癌HIF-1α表达水平对放化疗敏感性和临床预后的影响;并通过口腔癌细胞¹⁹²Irγ射线近距离放射治疗体外研究,了解口腔癌¹⁹²Irγ射线近距离放射治疗的放射生物学效应及其敏感性,为口腔癌临床治疗提供放射生物学实验基础,并为针对口腔癌低氧状态下的处于中枢调节地位的HIF-1α治疗研究提供实验基础。在此基础上,应用反义基因治疗手段反义阻断HIF-1α表达,研究主动下调HIF-1α表达水平对口腔癌放射敏感性更多还原

【Abstract】 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.更多还原