小激活RNA恢复抑癌基因HIC-1活性在乳腺癌的生物学效应研究

HIC-1 is a tumor suppressor gene located on chromosome 17p13.3, which is closely related to development and progression of breast cancer. The hypermethylation of HIC-1 promoter leads to the loss of tumor suppressor function by decreased or absent gene expression in breast cancer. RNA interference is widely used for knockdown of oncogenes, while RNA activation of tumor suppressor genes was initiated recently. This technology provides a convenient for studying the function of tumor suppressors. Our group established a RNA activating platform-on which, we successfully activated tumor suppressor gene HIC-1. We found that HIC-1 modulated cell growth, cell cycle and cell invasion. We assayed the whole transcriptome microarray after HIC-1 reactivation. A group of differential expressed genes and related pathways had been characterized and verified in subsequent qRT-PCR analysis. Receptor for hyaluronan-mediated motility (HMMR), a metastasis-associated gene is first characterized as a downstream target of HIC-1. HMMR play a role on cell migration and invasion in breast cancer. There is lack of reports about its association with HIC-1. In present study, we will explore the relation of HIC-1 and HMMR. The biological functions of HIC-1 and HMMR will be analyzed by a combination of saHIC-1 and siHMMR on breast cancer cells or animal model. Our study will clarify the regulatory relation of HIC-1-HMMR pathway, and uncover the molecular mechanism of HIC-1 tumor suppressor on breast cancer progression. The results will provide valuable references for developing new therapeutic strategy on gene interfering treatment.

HIC-1基因是位于17号染色体上与乳腺癌发生发展密切相关的抑癌基因，该基因失活主要与启动子区高甲基化有关。当前，以原癌基因为靶点的RNA干扰技术已广为应用，而以抑癌基因为靶点的RNA激活技术则最近几年刚刚兴起。RNA激活技术为研究抑癌基因功能提供了便利。本课题组最近建立了能够有效激活HIC-1抑癌基因的技术平台，并发现活化HIC-1在体外可有效抑制乳腺癌细胞的增殖、细胞周期以及细胞侵袭。通过全基因组表达谱芯片分析，首次发现HIC-1可以调控转移相关基因HMMR。HMMR为透明质酸受体，参与调控癌细胞的迁移与侵袭。本项目中我们将沿着这一重要发现，探讨HIC-1与HMMR的相互关系；以saHIC-1及siHMMR相结合方式探讨saHIC-1-HMMR通路在调控乳腺癌生长与浸润转移中的作用，明确HIC-1发挥抑癌作用的分子机制，为开发乳腺癌新型基因干预靶点提供实验依据。

HIC-1基因是位于17号染色体上与乳腺癌发生发展密切相关的抑癌基因，该基因失活主要与启动子区高甲基化有关。当前，以原癌基因为靶点的RNA干扰技术已广为应用，而以抑癌基因为靶点的RNA激活技术则最近几年刚刚兴起。RNA激活技术为研究抑癌基因功能提供了便利。本课题组在前期研究过程中，建立了能够有效激活HIC-1抑癌基因的技术平台，并发现活化HIC-1在体外可有效抑制乳腺癌细胞的增殖、细胞周期以及细胞侵袭。通过全基因组表达谱芯片分析，首次发现HIC-1可以调控转移相关基因HMMR。HMMR为透明质酸受体，参与调控癌细胞的迁移与侵袭。本项目首先应用免疫组织化学方法证实，抑癌基因HIC-1在乳腺癌组织呈明显低表达，致癌基因HMMR在乳腺癌组织呈明显高表达，HIC-1和受HIC-1调控的下游基因HMMR可能与乳腺恶性肿瘤的发生发展有关。然后应用siRNA和saRNA序列设计及转染技术，研究HIC-1和HMMR基因在不同遗传学背景乳腺癌细胞的生物学功能差异。结果表明，乳腺癌HIC-1转录抑制因子对HMMR基因具有抑制作用，乳腺癌细胞中HIC-1表达失活导致HMMR高表达，从而促进乳腺癌细胞的迁移和侵袭。通过以上研究，明确了HIC-1与HMMR基因的相互关系，以及HIC-1发挥抑癌作用的可能分子机制，为开发乳腺癌新型基因干预靶点提供了实验依据。