eIF3c通过下调DDIT3调控非小细胞肺癌增殖与凋亡的机制研究

Lung cancer is the most common cause of cancer-related death and the insight into the pathogenesis of lung cancer is of great significance. In recent years, abnormal protein synthesis has gained wide concern in cancer researches. eIF3c，a key element in the initiation of protein synthesis, is responsible for the translation initiation of eukaryotic cells and controls the cell cycle. Studies have shown that eIF3c is a tumor-promoting factor for breast cancer and glioma, but the role of eIF3c in lung cancer remains unknown. We investigated 48 lung cancer samples using tissue microarray-immunohistochemistry and found eIF3c was highly expressed in lung cancer tissues. Knockdown of eIF3c resulted in the significant decrease of cell proliferation, as well as the incrase of the activity of Caspase3/7, suggesting a crucial role of eIF3cin the proliferation and apoptosis of lung cancer cells. Our Gene expression microarray and IPA analysis reveals the synergistic effect of DDIT3 and eIF3c regulate the proliferation and apoptosis of lung cancer cells. Therefore, this study aimed to further investigate and verify the role of eIF3c in the proliferation and apoptosis of lung cancer cells in vitro and in vivo and explore whether eIF3c interacts with DDIT3 to mediate cell proliferation and inhibit cell apoptosis. Furthermore we will evaluate the.feasibility of eIF3c as a marker of clinical prognosis for lung cancer with the enlarging sample size. Our study will provide a new theoretical basis for the diagnosis and treatment and mechanism research of lung cancer.

肺癌是癌症相关死亡最常见的原因，深入了解其发病机制意义重大。近年来，异常蛋白质合成在肿瘤研究中受到广泛关注。eIF3c是蛋白质合成起始的关键元件，主要负责真核细胞的翻译起始与控制细胞周期。研究表明eIF3c是乳腺癌与胶质瘤的促癌因子，但在肺癌未见报道。我们通过48例肺癌样本的组织芯片-免疫组化检测发现eIF3c在肺癌组织中显著高表达，当敲减eIF3c后，肺癌细胞增殖明显减弱、凋亡显著增高，并且Caspase3/7酶活性增强，提示eIF3c影响肺癌细胞的增殖及凋亡。通过表达谱芯片及IPA分析发现，DDIT3可能与eIF3c共同作用调控肺癌细胞的增殖与凋亡。因此，本项目拟通过体内外实验进一步研究与验证eIF3c在肺癌细胞增殖、凋亡方面的作用，并探讨eIF3c是否与DDIT3相互作用介导增殖、抑制凋亡，同时扩大样本评估eIF3c为肺癌临床预后指标的可行性，为肺癌的诊疗与机制研究提供新的理论依据。

eIF3c是翻译起始复合物的重要组件，并且是一个具有肿瘤特性的致癌基因，然而在肺癌中未见有报道，其在肺癌的表达及功能尚不清楚。本课题组首次发现eIF3c在肺癌中异常高表达，由此我们推测 eIF3c在肺癌发生发展中有重要临床意义。本研究旨在探讨eIF3c在肺癌增殖和凋亡中的作用和机制，为预测该疾病的进展提供新的治疗性生物标志物。我们采用免疫组织化学法检测临床肺癌组织中eIF3c表达。用Lipofectamine 2000慢病毒eIF3c短发夹RNA (shRNA)转染细胞。通过Celigo和MTT测定评估细胞增殖。使用Caspase-3/7检测试剂盒评估Caspase-3/7活性，用于细胞凋亡检测。通过流式细胞术评估肺癌细胞的凋亡率。建立移植肿瘤裸鼠模型，阐明eIF3c在肺癌中的作用。通过mRNA微阵列分析探讨了eIF3c的潜在机制。在选择用于RT-qPCR的前30个上调和下调mRNA中，有5个被选中用于蛋白质印迹分析。结果提示：① eIF3c在肺癌细胞系和组织中异常高表达。② 敲低eIF3c后，肺癌细胞体外增殖受到抑制，肺癌细胞凋亡增加。③ 移植瘤裸鼠体内实验表明eIF3c促进肺癌的发生。④ 此外，mRNA微阵列分析在KD组和阴性对照组之间鉴定出189个上调和83个下调的差异表达mRNA。通过RT-qPCR和western blot验证，确定了3个下游基因(APP、HSPA1A和LMNB1)。因此，我们得到结论：eIF3c过表达可能通过调节APP/HSPA1A/LMNB1促进肺癌细胞的增殖并阻碍其凋亡。本研究通过体内外实验证实eIF3c具有促进肺癌细胞增殖，抑制凋亡的作用，是肺癌潜在的分子生物标志物，对肺癌的诊疗与机制研究提供一定的理论依据。