RAS诱导miR-134调节人卵巢癌细胞增殖和迁移的作用机制

RAS has long been known to play a significant role in signal transduction，cell proliferation, tumor formation and metastasis. RAS mutations are found in approximately 30% human cancer. After comparing the miRNA expression between T29 (human ovarian epithelial cell immortalized with SV40T/t antigens and the human catalytic subunit of telomerase) and T29H (T29 transformed with an additional oncogenic H-RASv12) cell lines, we found that the expression of miR-134 was induced obviously by H-RASv12. Over-expression or inhibition of miR-134 significantly affected cell proliferation and migration. Bioinformatics prediction and Dual-luciferase assay preliminary validated that PPP1R7, MYPT1 and PHLPP2 were the candidate targets of miR-134. In this project, based on the results above, further studies will be performed, including: 1) identifying the signaling pathway by which H-RASv12 regulates the expression of miR-134; 2) determining the effects of miR-134 and its candidate targets (PPP1R7，MYPT1 and PHLPP2) on cell proliferation and migration; 3) clarifying the molecular mechanism that H-RASv12 regulates the expression of miR-134 and target genes, and eventually cell proliferation and migration; 4) performing the correlation analysis between the expression of H-RAS, H-RASv12, miR-134 and target genes in ovarian cancer specimens. Taken together, our study will be beneficial for understanding the downstream functions of RAS-mediated pathway in human ovarian cancer, and providing new ideas for finding targets of anti-tumor drugs.

RAS在信号转导、细胞增殖、恶性转化及肿瘤转移等方面起着极其重要的作用。约30%的恶性肿瘤中存在RAS突变。通过比较卵巢癌细胞株T29H（稳定转染癌基因H-RASv12）和T29的miRNA表达谱，我们发现H-RASv12明显诱导miR-134的表达；瞬时转染miR-134影响细胞的增殖和迁移能力；生物信息学预测并初步确认了PPP1R7，MYPT1和PHLPP2为miR-134的候选靶基因。本项目拟在此基础上深入研究H-RASv12对miR-134的调节，研究miR-134及其候选靶基因PPP1R7，MYPT1和PHLPP2对细胞增殖和迁移的影响，以阐明H-RASv12调节miR-134及其靶基因，诱导细胞增殖和迁移的分子机制；并应用临床卵巢癌标本研究H-RAS，H-RASv12与miR-134及其靶基因的相关性，深入研究RAS信号通路的致癌机理，为寻找抗肿瘤药物的新靶点提供理论依据。

RAS蛋白在细胞的正常生理过程和肿瘤的发生发展等方面起着极其重要的作用。大约30%的恶性肿瘤中存在RAS突变。研究表明，miRNA在肿瘤发生过程中起着非常重要的作用，且能够被多种因子或信号通路调节。那么，miRNA是否参与了与肿瘤发生密切相关的RAS信号途径。通过比较两个细胞株T29（永生化的人卵巢上皮细胞）和T29H（在T29的基础上转染了一个组成型活性的癌基因H-RASv12，具有许多与自然的卵巢癌相似的特征）的miRNAs表达谱，我们发现H-RASv12明显诱导miR-134的表达。在此基础上，我们研究了H-RASv12对miR-134的调节机制；鉴定了miR-134的新靶基因；深入探讨了miR-134及其靶基因诱导卵巢癌细胞恶性表型和化疗药物耐受的分子机理。结果表明，H-RASv12通过激活ERK/JNK信号诱导miR-134的表达。进一步，我们鉴定了miR-134的新靶基因SDS22，发现miR-134能够调节SDS22的表达，进而诱导卵巢癌细胞的增殖，迁移和侵袭等恶性特征。深入研究发现，miR-134与SDS22和ERK/JNK形成正反馈环路，并提高卵巢癌细胞的化疗药物耐受性。这些成果为探讨miR-134在卵巢癌及其它肿瘤的发生发展中的作用提供了理论基础，同时也为寻找抗肿瘤药物的新靶点提供理论依据。在研究的过程中，我们还发现了一类受HBsAg诱导的miRNAs。我们证实，这些miRNAs能够通过作用于MICA/MICB的3′-UTR，抑制MICA/MICB的表达，降低自然杀伤细胞介导的细胞溶解作用；抑制miRNA的表达能够逆转HBsAg对MICA和MICB的抑制作用。因此，我们的结果表明，miRNAs 可以通过抑制天然免疫分子的表达，降低机体的抗肿瘤免疫应答 (Carcinogenesis, 2014), 此部分研究成果可能为探讨肿瘤免疫治疗提供新思路。