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B细胞易位基因2(B-cell translocation gene 2,BTG2)是细胞增殖抑制蛋白家族TOB/BTG的成员之一。目前的研究发现,BTG2参与包括肿瘤细胞在内的细胞分化、发育、凋亡等功能调节[1-6]。最近研究发现,人为提高BTG2的表达可以提高人乳腺癌T-47D细胞的放射敏感性,且可能与诱导细胞凋亡有关[7]。本研究通过提高和降低肿瘤细胞中BTG2的表达水平进一步了解BTG2在肿瘤细胞放射敏感性调节中的关键作用及其机制,为BTG2临床肿瘤放射治疗增敏性的预测和预后可行性提供实验基础和理论依据。
B细胞易位基因2的表达水平对肿瘤细胞放射敏感性的影响
Effect of B-cell translocation gene 2 alteration on radiosensitivity of cancer cells
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摘要:
目的 研究B细胞易位基因2(BTG2)表达水平的改变对肿瘤细胞放射敏感性的影响。 方法 通过pcDNA3-BTG2脂质体转染的方法提高细胞的BTG2的表达水平,利用噻唑蓝和细胞克隆形成实验研究细胞放射敏感性的改变,应用Western blot方法研究蛋白表达水平的变化。 结果 噻唑蓝和细胞克隆形成实验结果显示,在不同剂量的γ射线照射后,提高BTG2的表达水平可明显提高乳腺癌MCF-7和MDA-MB-231细胞的放射敏感性。免疫共沉淀-Western blot实验结果显示BTG2蛋白与DNA损伤修复和抗氧化蛋白乳腺癌易感基因1(BRCA1)相互作用,形成复合物。高表达的BRCA1明显地抑制了BTG2高表达对乳腺癌细胞放射敏感性的调节作用,而降低BRCA1的表达水平则提高了BTG2对乳腺癌细胞放射敏感性的调节作用。另外,肺癌细胞放射敏感性与其所含的BRCA1的表达水平成反比,而与BTG2的表达水平成正比。 结论 BTG2的高表达明显提高了肿瘤细胞的放射敏感性,其机制可能与其同BRCA1形成复合物有关。 Abstract:Objective To investigate the effects of B-cell translocation gene 2(BTG2) overexpression on the radiosensitivity of cancer cells. Methods Cancer cells with overexpression of BTG2 were established via stable transfection of full-length human BTG2 cDNA which was inserted into a mammalian expression plasmid pcDNA3(pcDNA3-BTG2). Cell survival was determined by thiazolyl blue tetrazolium bromide (MTT) and clonogenic survival assays. Protein-protein interaction was performed by immune precipitation(IP)-Western blot assay. Protein expression was assayed by Western blot assay. Results As demonstrated in MTT assay and clonogenic survival assay, enforced expression of BTG2 significantly enhanced radiosenstivity of human breast cancer MCF-7 and MAD-MB-231 cells. The BTG2 protein was able to be determined in the breast cancer susceptibility gene1(BRCA1) IP. Silence of BRCA1 enhanced the increased radiosensitivity by BTG2, however, co-overexpression of BRCA1 reduced the BTG2-mediated radiosenstivity. Finally, the radiosensitivity of lung cancer cell lines tested exhibited a positive relationship with the levels of BTG2 protein expression and a negative correlation with the levels of BRCA1 protein expression. Conclusion The present study further demonstrates that there is a significant relationship of radiosenstivity with BTG2 and BRCA1 expression, suggesting that BTG2 may be a new and important target in cancer radiotherapy via its binding to BRCA1. -
Key words:
- Neoplasms /
- Radiation tolerance /
- B-cell translocation gene 2 /
- Gene, BRCA1
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