Upstream Regulation and Downstream effectors of c-MYC in Ovarian Cancer

摘要 卵巢癌仍然是女性癌症相关死亡的重要原因，约有 22,440 例新发卵巢癌 预计 2017 年将有 14,080 例病例和约 14,080 例死亡。与本提案的目标一致， 迫切需要确定针对晚期和耐药高级别浆液的更好治疗靶点 卵巢癌（HGSOC）是妇科癌症中恶性程度最高、致死率最高的。其中一种可能性是 c-MYC，一种在大多数癌症（包括 HGSOC）中高度丰富的癌基因。我们的研究机构之前的研究 团队使用“癌症基因组图谱”（TCGA）数据门户显示 HGSOC 发生复发 对于 c-MYC 表达较高的患者，速度更快。此外，小干扰 RNA (siRNA) 介导的 c-MYC 在卵巢癌小鼠模型中，沉默可减少细胞增殖并减少肿瘤生长。在一起， 这些结果表明 c-MYC 可能是 HGSOC 患者的临床相关靶点。虽然 c-MYC 过度表达的分子机制已在不同类型的癌症中得到广泛研究， 导致 HGSOC 中 c-MYC 上调的机制尚未得到解决。初步结果来自 我们的研究团队表明，c-MYC 可以通过 HGSOC 中的 microRNA 进行转录后调节。 MicroRNA (miRNA) 是一种小型非编码 RNA，可以与数千种不同的RNA 结合。 信使RNA并抑制蛋白质合成。通过使用生物信息学和分子研究，我们确定 一些可能调节卵巢癌细胞中 c-MYC 表达的 miRNA。最重要的是，短暂的 转染这些 miRNA 的寡核苷酸 miRNA 模拟物表明 miR-98、miR-106a 和 miR-18a 显着降低c-MYC蛋白水平，并减少卵巢癌细胞的细胞增殖。 总之，我们的数据提供了对 HGSOC 中 c-MYC 调节新机制的见解。我们的整体 假设 miR-98、miR-106a 和 miR-18a 转录后调节 c-MYC 表达 HGSOC。此外，我们将检验 c-MYC 调节与细胞存活相关的关键基因的假设 并具有 HGSOC 细胞的顺铂耐药性。该假设将通过追求以下内容来解决 具体目标：（1）鉴定HGSOC细胞中转录后调节c-MYC表达的microRNA； (2) 研究siRNA介导的c-MYC沉默的生物学后果和治疗效果 在 HGSOC 中与 miR-98、miR-106a 或 miR-18a 模拟物组合； (3) 阐明 c-MYC 下游 卵巢癌细胞中的效应子。我们对耐药分子机制领域的贡献将 详细阐述了 HGSOC 中 c-MYC 的上游调控和下游效应器。在 响应“健康差异合作研究中心”（RCMI）的主要使命之一， 该提案将提高少数民族机构研究人员在基础和转化方面的参与度 癌症研究，并将对当地研究生和本科生进行前沿技术培训 癌症研究中的技术和新颖概念。

ABSTRACT Ovarian cancer remains an important cause of female cancer-related deaths, with approximately 22,440 new cases and about 14,080 deaths predicted for 2017. Consistent with the objective of this proposal, there is an urgent need to identify better targets for therapy against advanced and drug-resistant high-grade serous ovarian cancer (HGSOC), the most malignant and lethal of the gynecological cancers. One such possibility is c-MYC, an oncogene highly abundant in most cancers, including HGSOC. Previous studies by our research team using “The Cancer Genome Atlas” (TCGA) data portal showed that recurrence of HGSOC occurred faster for patients with higher c-MYC expression. In addition, small-interference RNA (siRNA)-mediated c-MYC silencing decreased cell proliferation and reduced tumor growth in an ovarian cancer mouse model. Together, these results suggest that c-MYC could be a clinically relevant target for HGSOC patients. Although the molecular mechanisms of c-MYC overexpression have been extensively studied in different types of cancer, the mechanism leading to c-MYC up-regulation in HGSOC have not been addressed. Preliminary results from our research team indicate that c-MYC could be regulated post-transcriptionally by microRNAs in HGSOC. MicroRNAs (miRNAs) are small non-coding RNAs that can potentially bind to thousands of different messenger RNAs and inhibit protein synthesis. By using bioinformatics and molecular studies we identified several miRNAs that potentially regulate c-MYC expression in ovarian cancer cells. Most important, transient transfection of oligonucleotide miRNA mimics for those miRNAs showed that miR-98, miR-106a and miR-18a significantly decreased the c-MYC protein levels, and reduced the cell proliferation of ovarian cancer cells. Together, our data provide insight into novel mechanisms of c-MYC regulation in HGSOC. Our overall hypothesis is that miR-98, miR-106a and miR-18a post-transcriptionally regulate c-MYC expression in HGSOC. In addition, we will test the hypothesis that c-MYC regulates key genes associated with cell survival and with the cisplatin resistance of HGSOC cells. This hypothesis will be addressed by pursuing the following Specific Aims: (1) identify the microRNAs post-transcriptionally regulating c-MYC expression in HGSOC cells; (2) investigate the biological consequences and therapeutic effects of siRNA-mediated c-MYC silencing in combination with miR-98, miR-106a or miR-18a mimics, in HGSOC; and (3) elucidate the c-MYC downstream effectors in ovarian cancer cells. Our contribution to the field of molecular mechanisms of drug resistance will be a detailed elucidation of the Upstream Regulation and Downstream Effectors of c-MYC in HGSOC. In response to one of the main missions of the “Center for Collaborative Research in Health Disparities” (RCMI), this proposal will improve the participation of researchers in minority institutions in basic and translational cancer research and will result in the training of local graduate and undergraduate students in cutting-edge technology and novel concepts in cancer research.