Luminal型乳腺癌特异高表达的长链非编码RNA LOL在肿瘤进展中的机制研究

Luminal breast cancer accounts for more than two-thirds of all breast cancers and has a sustained risk of late disease recurrence and death. Considerable numbers of patients suffer from anti-endocrine therapy (such as tamoxifen) resistance, which have also severely affected their survival. Therefore, it is of great significance to explore new potential therapeutic targets for luminal breast cancer. At present, there are few studies on luminal breast cancer related long non-coding RNA (lncRNA). For this situation, by using transcriptome analysis, we found a novel luminal breast cancer-specific lncRNA LOL. Using in vitro and in vivo experiments and clinical data analysis, we found that LOL plays vital roles in tumor growth, tamoxifen resistance and patients’ prognosis. We also found that LOL may directly bind to let-7 and RBM14 (CoAA). However, the mechanism of its functions remains to be further explored. To this end, we hypothesized that LOL interacts with let-7 and RBM14 to influence signaling pathway related with tumor growth and tamoxifen resistance. In order to verify the hypothesis, we will use a variety of luminal breast cancer cell lines, tamoxifen resistant cell lines and transplanted tumor animal models, RNA Pull - down, mass spectrum analysis, RNA immunoprecipitation, Western Blot, virus transfection, RNA interference and so on, to clarify the molecular mechanism of LOL. This research will provide a new potential therapeutic target for luminal breast cancer, offering important guidance for its diagnosis, treatment and prognosis.

Luminal型乳腺癌（LBC）占所有乳腺癌的2/3以上，其拥有长期的持续增高的复发和死亡风险。部分LBC病人对他莫昔芬耐药，亦严重影响了病人的生存。故探寻LBC新的潜在治疗靶点仍有重大的意义。目前，针对LBC相关lncRNA的研究较少。针对这一现状，我们利用转录组分析，首次发现了在LBC中特异性高表达的lncRNA LOL。通过体内、外实验和临床数据分析发现，LOL在肿瘤生长，他莫昔芬耐药和病人预后中均起重要的作用，且与let-7和RBM14蛋白相互结合。但其作用机制还有待进一步探讨。为此，我们提出假说，LOL通过调控let-7-下游靶基因及RBM14-MYC信号通路，进而影响肿瘤生长和他莫昔芬耐药。为了验证该假说，我们将采用RNA-pull down，RIP等手段，从分子、细胞、组织以及动物模型等多方面阐述LOL的作用分子机制，为LBC提供新的潜在治疗靶点和理论依据。

Luminal型乳腺癌(LBC)占所有乳腺癌的2/3以上，其拥有长期的持续增高的复发和死亡风险。部分LBC病人对他莫昔芬耐药，亦严重影响了病人的生存。故探寻LBC新的潜在治疗靶点仍有重大的意义。目前，针对LBC相关lncRNA的研究较少。针对这一现状，我们利用对21对LBC癌与癌旁标本的转录组测序和分析，首次发现了在LBC中特异性高表达的lncRNA LOL (luminal lncRNA of luminal)。通过体内、外实验和临床数据分析发现，LOL在肿瘤生长、他莫昔芬耐药和病人预后中均起重要的作用。它作为let-7 microrna的天然海绵，调节肿瘤生长和他莫西芬耐药。在他莫昔芬处理的亲代MCF-7细胞中，LOL过表达比阴性对照表现出增殖优势。抑制TamR MCF-7细胞中的LOL，恢复了细胞对他莫西芬的敏感性。令人惊讶的是，我们证明了LOL是从一个增强子的基因组位点转录而来，以维持其在腔内BC中的高表达，并且它对增强子调节因子(如ZMYND8和BRD4)极其敏感。雌激素剥夺或ERα信号通路阻断可进一步刺激LOL表达，从而促进肿瘤进展。对374例管腔乳腺癌样本的临床分析表明，LOL是管腔BC患者生存不良的独立预后因素。综上所述，使用临床前/临床药物(如BRD4抑制剂)靶向LOL，可能是一种有前途的抑制LBC进展和他莫西芬耐药的方法。

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