BTG2甲基化调控肝癌细胞放疗敏感性的分子机制研究

功能基因DNA甲基化状态和miRNA与肿瘤放疗敏感性密切相关。BTG2是调控肿瘤放疗敏感性的重要功能基因。我们前期证实BTG2是miR-29b的靶基因，miR-29b与BTG2在肝癌组织和细胞中都呈低表达，均未发现甲基化现象，而在肝癌细胞电离辐射后BTG2水平上调并发生高甲基化，而目前这种甲基化转换现象与miRNA和肝癌放疗敏感的相关性研究尚未见报道。miR-29b是DNMTs上游miRNA，可负向调节DNA甲基化；而近期报道DNMTs通过结合BTG2甲基化位点调节其转录功能。由此我们提出假设：miR-29b通过直接作用于BTG2或/和通过DNMTs介导BTG2甲基化调控肝癌细胞放疗敏感性。本课题拟采用焦磷酸测序、报告基因分析、CHIP和WB等方法旨在从表观遗传调控2个角度揭示BTG2甲基化调节肝癌放疗敏感性作用方式，拓展miR-29b调控BTG2的新机制，为诠释肝癌放疗抵抗提供新思路。

The status of DNA methylation and microRNA is associated with the radiotherapy sensitivity. BTG2 is a gene that could regulate key functional genes related to tumor chemoradiotherapy sensitivity. DNA methylation transferase (DNMTs) are target genes of miR-29b that has the ability of regulation on DNA methylation. Our previous study have demonstrated that BTG2 is a target gene of miR-29b, and both of them are down-regulated in liver cancer tissues and liver cancer cells. Methylation does not exist in BTG2 gene, however, the level of BTG2 expression increases and BTG2 gene has to be found to exist methylation in liver cancer cells after radiation. However, the relationship between methylation and tumor radiotherapy sensitivity has not been reported yet. Recent study has reported that BTG2 could regulate its translation function by binding with DNMTs. Thus, we propose hypothesis that miR-29b could regulate BTG2 directly by targeting BTG2-3’UTR or could induce BTG2 methylation to regulate radiotherapy sensitivity of liver cancer cell by DNMTs. From two points of epigenetics, we elaborate “The mechanism on the regulation of BTG2 methylation in HCC radiotherapy sensitivity” according to pyrosequencing, luciferase reporters, CHIP and WB etc, which will expand the new mechanism about the regulation of miR-29b to BTG2 and provide theory basis for explaining the mechanism of methylation in regulation of HCC radiosensitivity.