H2AX/microRNAs作用模式调控肺癌细胞凋亡的机制研究

Phosphorylation of H2AX (γ-H2AX) is considered to be a biomarker for DNA double-strand breaks (DSB). In recent years, a large number of studies have shown that γ-H2AX is required for apoptosis. H2AX is considered to be a new tumor suppressor which closely related to the fate of tumor cells. However, the specific mechanisms of H2AX in tumor cell apoptosis remain unclear. Our previous studies showed that H2AX played a key regulatory role in cancer cells apoptosis, and microRNAs expression level was also changed. Therefore, we speculate that H2AX may regulate the expression of microRNAs, and then regulate cancer cell apoptosis at the epigenetic level. This project will uncover regulation of microRNAs by H2AX, identify key target genes of microRNAs in apoptosis, and make clear the molecular mechanism of regulation of H2AX in apoptosis. This project contributes to a better understanding of the epigenetic regulation function of the tumor suppressor protein H2AX, and also provides relatively specific molecular targets for the treatment of lung and other tumors.

磷酸化H2AX（γ-H2AX）是DNA发生双链断裂时的一个标记物。最近研究发现γ-H2AX是细胞凋亡所必需，尤其与肿瘤细胞的命运密切相关，因而被认为是一种新的抑癌蛋白。然而H2AX在肿瘤细胞凋亡中的具体调控机制仍不十分清楚。我们前期工作发现，肺癌细胞发生凋亡时，H2AX起关键调控作用，microRNAs表达谱也发生显著改变。因此，我们推测H2AX可能通过调节microRNAs表达，进而在表观遗传水平调控肺癌细胞凋亡。本项目拟采用高通量研究手段分析H2AX调节的microRNAs表达谱，并对microRNAs的表达调控及其影响肺癌细胞凋亡的作用机制进行深入研究，明确microRNAs的关键靶基因及其功能，深度揭示 H2AX调控肿瘤细胞凋亡的分子机制。本项目的开展有助于深入了解抑癌蛋白 H2AX 在肺癌细胞凋亡中的表观遗传学功能，并为肺癌等其它肿瘤临床治疗提供相对完整而具体的分子靶点。

磷酸化H2AX（γ-H2AX）是DNA发生双链断裂时的一个标记物。最近研究发现γ-H2AX与肿瘤细胞凋亡密切相关，然而H2AX在肿瘤细胞凋亡中的具体调控机制仍不十分清楚。本课题采用miRNAs芯片技术以H2AX敲降的肺癌A549细胞为研究对象，筛选得到了受H2AX负调控的miRNA-3196，进一步研究发现H2AX磷酸化负调控miR-3196表达并且miRNA-3196通过其功能性靶基因PUMA抑制VP-16诱导的肺癌细胞凋亡。另外，我们详细研究了H2AX调控miRNA-3196表达的机制，我们发现γ-H2AX能够结合miRNA-3196启动子区增强该启动子区H3K27甲基化水平并抑制RNA聚合酶II与该启动子区的结合进而影响miRNA-3196表达。本研究发现H2AX/miRNA-3196/PUMA在肺癌细胞的凋亡中发挥了重要的作用，为肿瘤尤其是肺癌诊疗提供了新的潜在分子靶点，具有一定的潜在应用价值。