miR-34甲基化调控胃癌干性特征的作用及机制研究

Gastric cancer is one of the most prevalent cancer in our country. Our previous results demonstrated that restoration of functional miR-34 inhibits cell growth in p53-deficient human gastric cancer cells.The mechanism of miR-34-mediated suppression of gastric cancer cell self-renewal might be related to the direct modulation of downstream targets including Bcl-2,and Notch, implying that miR-34 may be involved in the maintenance of gastric cancer stem cell self-renewal/stemness. More significantly, miR-34 might be inactivated by CpG methylation. .In the present study, the methylation status of miR-34 will be investigated in multiple human gastric cancer cell lines and clinical samples The stemness phenotype will be detected after restoration of functional miR-34 by lentiviral system or demethylation, followed by the exploration of relative downstream signaling pathways. Our study will elucidate the link between epigenetic of miR-34 and function of its targeted gene. The current study will demonstrate that the regulatory mechanisms of gastric cancer cell self-renewal by tumor suppressor miR-34. Epigenetic silencing of miR-34 may hold significant promise as a novel therapeutic strategy of human gastric cancer.

胃癌在我国发病率居各类肿瘤之首，我们的前期研究发现重建miR-34可抑制胃癌细胞生长, miR-34的下游靶基因Bcl-2、Notch等是胃癌自我更新能力的关键分子，提示miR-34可作为抑癌基因通过其下游通路调控胃癌干性。进一步研究发现miR-34可能存在基因甲基化失活，因而在胃癌中低/缺失表达。miR-34的甲基化状态有可能成为各级不典型增生乃至胃癌风险/复发的预警信号。.本项目将以胃癌和各级不典型增生临床标本为研究对象，分析其中miR-34启动子区域的甲基化状态，通过去甲基化、慢病毒系统等手段重建miR-34表达，深入探讨miR-34的基因表观遗传学与其下游靶基因功能学的关系。全面阐明miR-34调控胃癌自我更新能力的作用机制，有助于更好地理解miR-34逆转胃癌恶性生物学行为的病理过程，进而为下一步以miR-34为新靶点预警分子开展胃癌的预防治疗提供有益的思路和方法。

本项目在既往研究提示miR-34可能通过靶向胃癌自我更新能力从而抑制胃癌生长的基础之上，进一步探讨miR-34的表观遗传沉默与胃癌干性特征的关系。从基因组到功能学研究miR-34基因启动子甲基化状态及其通过下游靶基因调控胃癌干性特征的作用及机制，阐明miR-34甲基化失活与胃癌恶性程度的相关性，深化理解miR-34逆转胃癌恶性生物学行为的病理过程，进而为下一步以miR-34为新靶点预警分子开展胃癌的预防治疗提供有益的思路和方法。.我们的研究发现胃癌中miR-34启动子区域高甲基化，从而导致miR-34沉默失活，在胃癌细胞中重建miR-34表达后，可通过Bcl2, SIRT1，Notch1和Notch2等下游靶基因，靶向胃癌自我更新能力，抑制胃癌细胞干性特征，从而逆转胃癌的恶性生物学表型。miR-34的甲基化状态与胃癌恶性程度相关，miR-34的低表达/缺失表达有可能成为各级不典型增生乃至胃癌风险/复发的预警信号。