HuR与miR-888拮抗调控CDC7在非小细胞肺癌发生及转移中的机制研究

Lung cancer plays a key role on mortality of cancer patients. Although target therapies improved survival rate of cancer patients, 40% of cancer patients have no correlation on oncogenes. Searching for the new therapeutic target is very important.CDC7 overexpressed across several species of tumor cell. As the previous experiment shows, DNA synthesis and cell proliferation was inhibited after knocking down the expression of CDC7 in non-small cell lung cancer cell line A549.In addition, p38 signal pathway will be activated following the low expression of CDC7. Based on the above, CDC7 could be one therapeutic target of non-small cell lung cancer, but mechanism on the regulation of the expression of CDC7 remains elusive.In the previous studies, we verified miR-888 could down-regulate the expression of CDC7, however, miR-888 and its target CDC7 were proved to be high expressed in non-small cell lung cancer. We predict miR-888 inhibited the expression of CDC7 but activated the p38 signal pathway, activation of p38 MAPK signal pathway could induced the accumulation of RNA binding protein HuR in the cytoplasm, furthermore, HuR could bind with the mRNA of CDC7 and promote the translation of CDC7. High abundance of HuR and CDC7 play a significant role on the carcinogenesis and metastasis of non-small cell lung cancer. In order to certificate the above presumption, the regulation of miR-888 and HuR on the expression of CDC7 will be proved with molecular assay, animal model and clinical tries, and explain miR-888, HuR independently and antagonistically regulating on the expression of CDC7 which impacts on impact on the carcinogenesis and metastasis of non-small cell lung cancer, then we certificate miR-888 as non-invasive biomarkers for cancer through comparing the expression of miR-888 in tumor patient and normal, This project are important for diagnosis and therapy of non-small cell lung cancer.

肺癌是导致癌症死亡主要因素之一，尽管靶向治疗能很大改善生存率，但仍有40%患者无已知靶点，因此寻找新靶点对癌症治疗至关重要。CDC7在多种肿瘤细胞中高表达，前期实验显示，在肺癌细胞中敲低CDC7可抑制细胞增殖并诱导凋亡。因此，CDC7可作为癌症潜在治疗靶点，但其调控机制并不清楚。我们发现miR-888可下调CDC7表达，但在非小细胞肺癌组织中，miR-888和靶分子CDC7均表达上调，我们推测在癌组织中，miR-888抑制CDC7表达并激活p38途径，引起HuR在胞质中积累，进而上调CDC7表达，HuR及CDC7上调导致非小细胞肺癌发生及转移。为证实该假说，我们将从分子—动物—临床三个水平证实miR-888、HuR对CDC7的调控，揭示其调控对非小细胞肺癌发生和转移的影响，并结合临床血清标本分析，证实miR-888可做为非小细胞肺癌非侵袭性肿瘤标志物，为非小细胞肺癌诊断及治疗提供理论基础。

肺癌是导致癌症死亡主要因素之一，尽管靶向治疗能很大改善生存率，但仍有40%患者无已知靶点，因此寻找新靶点对癌症治疗至关重要。CDC7在多种肿瘤细胞中高表达，前期实验显示，在肺癌细胞中敲低CDC7可抑制细胞增殖并诱导凋亡。因此，CDC7可作为癌症潜在治疗靶点，但其在非小细胞肺癌病人中的表达及调控机制并不清楚。本课题从细胞水平、动物水平、临床水平研究miR-888、HuR、CDC7之间的调控通路，并揭示其对非小细胞肺癌发生及转移的影响。在细胞水平上，一方面，miR-888通过结合CDC7 3'-UTR抑制CDC7的表达，而HuR则通过结合CDC7 3'-UTR促进CDC7的表达；另一方面，miR-888下调CDC7表达，激活p38途径，进而促进HuR的上调。在动物水平上，过表达miR-888或敲低CDC7均能明显抑制裸鼠肿瘤的生长，而过表达HuR则促进裸鼠肿瘤的生长；当过表达miR-888同时过表达HuR时，其肿瘤生长较单独过表达miR-888强，而比单独过表达HuR弱；过表达miR-888的同时敲低HuR，对裸鼠肿瘤生长抑制最为明显。在临床水平上，miR-888及CDC7在非小细胞肺癌组织中均明显上调，且miR-888表达与肿瘤分期呈正相关。此外，相比较非肿瘤人群，miR-888在非小细胞肺癌病人血清中明显上调。在功能上，一方面，miR-888通过下调CDC7抑制细胞的增殖及肿瘤的形成，而HuR则通过上调CDC7促进细胞的增殖及肿瘤的形成；另一方面，miR-888通过调控E-cadherin及TIMP2促进细胞的侵袭和转移，而HuR通过调控CDC7促进肿瘤细胞的侵袭和转移。此外，我们扩大肿瘤类型分析CDC7发现，CDC7在食管鳞状细胞癌病人标本中明显上调，敲低CDC7可促进食管鳞状细胞癌对化疗的敏感性。综合上述结果，本研究揭示，miR-888具有作为非小细胞肺癌诊断非侵袭性肿瘤标志物的潜能；CDC7可作为肿瘤治疗潜在的广谱靶点。