CPSF4调控hTERT表达及在肺癌发生发展中的作用机制和临床意义

Elevated hTERT activity is an important indicator of lung tumorigenesis. It is necessary to discover and identify tumor-specific protein factors which regulate hTERT expression. In previous studies, the applicant established a magnetic biopanning technique and successfully used it to pulldown the binding proteins of functional small molecules(PloS One,2012).In our preliminary study, we discovered and identified a new hTERT promoter binding protein CPSF4 in lung cancer cells by using the same technique. We found that CPSF4 was highly expressed in lung cancer cells and tissues, promoted hTERT transcription activation, and affected lung cancer cell growth. However, it is unclear that CPSF4 regulates lung tumorigenesis through hTERT signaling pathway and the underlying mechanisms and clinical implications. In this study, we will knockdown or overexpress the expression of CPSF4, and study the effects of CPSF4 on hTERT expression, telemerasae activity, telomere length, tumor cell growth and apoptosis as well as their underlying signaling pathways in human lung cancer cell lines and animal models, thereby revealing the molecular mechanisms and biological functions of CPSF4. Moreover,we will analyze the expression levels of CPSF4 and hTERT in tumor tissues from lung cancer patients by tissue arrays, and then assess the relationship between CPSF4 and lung cancer staging, metastasis, recurrence and patient survival, thereby elucidating its clinical significance. The results from our study will provide theoretical and experimental basis for identification of CPSF4 as a new therapeutic target for lung cancer treatment.

hTERT活性增高是肺癌发生发展的重要指标，发现和确定调控hTERT表达的肿瘤特异性蛋白因子十分必要。前期研究中申请者建立了磁生物淘洗技术,成功垂钓出小分子药物结合蛋白（PloS One，2012）。预实验采用同样技术，在肺癌细胞中垂钓确定了一个新的hTERT启动子结合蛋白CPSF4，并证实其在肺癌细胞和组织中高表达，促进hTERT转录活性，影响肺癌细胞生长。但CPSF4通过hTERT信号通路调控肺癌发生发展的机制和临床意义，尚不清楚。本项目拟在肺癌细胞和动物模型中敲低或过表达CPSF4，研究其对hTERT表达、端粒酶活性、端粒长度、肿瘤细胞生长和凋亡以及相关信号通路的影响，揭示其生物学功能和分子机制。并利用组织芯片分析肺癌患者组织中CPSF4和hTERT的表达水平，评估其与肺癌发生、转移、复发和预后的相关性，确定其临床意义。本项目将为确立CPSF4作为肺癌治疗的新靶点提供理论和实验依据。

人端粒酶逆转录酶（hTERT）在肺癌发生发展中发挥着重要作用，然而其具体的转录调控机制尚不十分明确。我们前期研究发现CPSF4可以作为转录因子上调hTERT的转录和表达并促进肺癌细胞的生长。本项目拟通过研究进一步揭示CPSF4调控hTERT转录的具体分子机制和临床意义。我们通过近两年多的研究发现，在肺癌细胞中，CPSF4可以与转录共活化子CBP相互作用，被CBP乙酰化，二者共同锚定在hTERT的启动子区协同调控hTERT的转录和表达，进而协同调控肺癌细胞的生长和凋亡以及与此相关的分子信号通路。在临床组织样本中，我们发现CBP与CPSF4同样存在表达相关性，CBP高表达的病人中，CPSF4的高表达也占有较大的比例，而且二者同时高表达的病人总的存活率较同时低表达的病人低很多。因此，通过研究我们不仅找到了肺癌细胞中hTERT的新的转录调控因子CPSF4, 而且揭示了其调控hTERT转录和表达的关键分子机制，表明CBP在CPSF4/hTERT信号通路中的关键协同性，从而为肺癌的分子治疗提供了新的候选靶点，也为肺癌的多靶点协同治疗提供了一定的理论和实验依据。