长非编码RNA介导乳腺癌辐射抵抗及其分子机制研究

Breast carcinoma is a leading cause of cancer deaths among women every year worldwide. Radiotherapy is adopted as a commonly used therapy for patients with breast cancer. Heretofore, mounting clinical and epidemiological studies have reported that patients with breast neoplasms exhibit remarkably radioresistance, resulting in poor prognosis. However, the underlying mechanism remains largely unknown. HOX transcript antisense RNA (HOTAIR), as a long non-coding RNA, has been associated with a spectrum of biological functions and the disruption of these functions play a critical role in the development of cancer. It has been reported that HOTAIR is overexpressed in various cancer, such as breast carcinoma. Nevertheless, whether HOTAIR underpins the radioresistance of breast cancer is still enigmatic. Thus, we aim to explore whether HOTAIR contributes to the radioresistance of breast cancer cells. Our previous observation reveals that HOTAIR is able to strengthen the radioresistance of breast cancer cells in vitro. In addition, HOTAIR up-regulates the mRNA and protein levels of HSP70 in breast cancer cells in a dose-dependent fashion treated with radiation. These results give us a clue to hypothesize that HOTAIR indeed involves in the radioresistance of breast carcinoma cells. Therefore, we further seek to investigate the molecular mechanism by which HOTAIR enhances the radioresistance of breast cancer cells. We also would like to validate our conclusions using mouse models as well as clinical breast cancer tissues. Our finding will provide new insights into the mechanism of breast cancer radioresistance and a novel target for individual therapy of breast cancer patients.

我国乳腺癌的发病率与致死率均超过全球平均水平。放疗是治疗乳腺癌惯用的手段，但流行病学研究显示不少乳腺癌患者表现出辐射耐受，导致治疗效果不佳。长非编码RNA（lncRNA）是分子生物学领域的研究热点，报道指出lncRNA在个体生理和病理的进程中发挥着重要的作用。基于此，本课题以乳腺癌为模型，主要探讨lncRNA HOTAIR在乳腺癌辐射抵抗中的作用并揭示其具体分子机制。实验拟应用分子克隆、报告基因、流式细胞术等分子生物学技术，验证HOTAIR在乳腺癌细胞辐射抵抗中的作用，并阐明其激活的信号通路及具体作用方式。结合临床标本验证HOTAIR与下游基因在乳腺癌组织中的相关性，并结合回访资料探讨HOTAIR与乳腺癌患者放疗预后的关系。最后运用裸鼠成瘤模型佐证上述结果。本研究将揭示lncRNA在肿瘤细胞辐射抵抗中的作用，并为乳腺癌个体化治疗提供新的依据和治疗靶点。

我国乳腺癌的发病率与致死率均超过全球平均水平。放疗是治疗乳腺癌惯用的手段，但流行病学研究显示不少乳腺癌患者表现出辐射耐受，导致治疗效果不佳。国内外研究显示长非编码RNA能够通过多种方式在转录和转录后等水平调控基因的表达。基于此，本课题以乳腺癌为模型，以长非编码RNA HOTAIR为研究对象，提出“长非编码RNA HOTAIR参与介导乳腺癌细胞辐射抵抗”的科学假说。我们的实验结果显示，内源性HOTAIR高表达与乳腺癌细胞辐射抵抗呈正相关。HOTAIR通过“海绵”作用吸附miRNA，上调热休克蛋白HSPA1A表达，从而促进乳腺癌细胞辐射抵抗。本项工作揭示了长非编码RNA HOTAIR是提高乳腺癌放射治疗效果的潜在靶点。该部分工作处于投稿阶段。此外我们的研究发现低剂量照射能够上调肝细胞中长非编码RNA HULC的表达。HULC的高表达下调其“邻居基因”CDKN1，促进细胞周期进程，从而导致肝细胞增殖异常。.意外和医源性照射伴随着严重且不可逆的急慢性辐射损伤。急慢性辐射损伤的救治一直是放射医学领域的临床难题。肠道微生物生态系统是哺乳动物体内最庞杂的微生态系统，肠道菌群的紊乱将引发肠内外多种疾病。为研发缓解与治疗急慢性辐射损伤的新技术和新方法，我们以肠道微生物为抓手，开展了一系列的研究。我们的结果显示：腹部局部照射改变受照小鼠肠道微生物组、小肠组织microRNA 表达谱，导致其认知与记忆障碍；节律异常使宿主肠道微生物丰度下降，影响个体对于电离辐射的耐受性；利用健康小鼠的肠道菌群进行粪菌移植显著增加受照小鼠肠道完整性和功能，重构受照小鼠肠道微生物组成，重编程受照小鼠肠道组织基因表达谱，缓解受照小鼠造血系统损伤和肠型急慢性辐射损伤；口服水素水能够重塑腹部局部照射小鼠肠道微生物组，缓解与救治肠型急慢性辐射损伤。上述前期实验结果表明肠道微生物与宿主的电离辐射敏感性密切相关；通过重塑宿主肠道微生物的丰度与组成能够缓解和救治受照小鼠肠型急性辐射损伤；粪菌移植技术能够用于缓解与救治意外或医源照射引起的急慢性辐射损伤。