PTENp1靶向miRNAs调控PTEN的机制及对口腔鳞癌增殖和化疗耐药的影响

Mutations and deletions in the genes PTEN are rarely reported in oral squamous cell carcinoma, but its protein level was significantly lower, mainly due to the regulation of miRNAs. The latest study found the relationship between PTEN and its pseudogene PTENP1. PTENP1 did not coding protein, However, PTEN-targeting miRNA seed matches within the high homology region between PTEN and PTENP1. PTENP1 could compete for the binding of many PTEN-targeting miRNAs, regulate cellular levels of PTEN and affect the PI3K/AKT pathway. It may be the new regulator of PTEN. The pseudogene PTENP1 showed decreased expression in oral dysplasias, which raises the intriguing possibility mechanism that the PTENP1-PTEN regulatory network is similarly perturbed in oral cancer. In our previous study, we found that miRNA21 could regulates PTEN expression in oral squamous cell carcinoma and affect the cell proliferation and drug resistance. This project intends to elaborates the downregulation mechanism of PTENp1 in oral squamous cell carcinoma, clarify the the role and position of the new regulator PTENp1 in the mechanism of PTEN regulatory network.This project will include the analysis of clinical samples, in vitro studies of cell and molecule biology experiment, and the in vivo studies in nude mouse model. The purpose of this study is to test this new regulatory mechanism and the role of the new regulator PTENp1, verify its function in the cell proliferation and drug resistance and thus provide a new target for gene therapy and drug resistance treatment for oral squamous cell carcinoma.

在口腔鳞状细胞癌中，PTEN基因缺失及突变少见，但蛋白水平降低明显，主要受miRNAs的调控。最新研究发现PTEN的假基因PTENp1虽不编码蛋白，但和调控PTEN的多个miRNA有结合位点。因此PTENp1可以和PTEN竞争性结合miRNAs，间接调控PTEN表达，影响PI3K/AKT信号通路。口腔癌前病变中PTENp1下调，也符合上述调控机制的推论。结合前期研究发现，口腔癌中miRNA21可以调控PTEN表达，并影响口腔鳞癌增殖及耐药。本课题拟从临床标本分析，细胞生物学和分子生物学的体外研究、裸鼠模型的体内研究明确口腔鳞癌中PTENp1下调机制，阐明新的调控者PTENp1在调控PTEN-mRNA及蛋白表达中的角色和地位，检验这一新的调控机制对口腔鳞癌增殖和化疗耐药的影响，从而为口腔鳞癌的基因治疗和耐药治疗提供一个新的靶点。

本课题通过口腔鳞状细胞癌（OSCC）临床标本分析，细胞生物学和分子生物学的体外及裸鼠移植瘤的体内实验研究了PTENp1作为miR-21海绵对PTEN表达的调节机制及对OSCC细胞功能学的调控效用。研究结果显示PTENp1在OSCC组织和细胞中的表达下调，相关性分析提示PTENp1与PTEN的表达呈负相关；PTENp1可作为内源竞争性RNA通过抑制miR-21的表达解除miR-21对PTEN的转录抑制，经AKT信号通路抑制OSCC细胞的增殖活性及克隆形成能力，同时阻滞S-G2期转换。采用裸鼠移植瘤实验也证实了PTENp1与PTEN在OSCC肿瘤中的表达。OSCC临床样本分析显示PTENp1与PTEN与OSCC患者组织分型及预后呈负相关。本课题通过体内外实验揭示了PTENp1、PTEN和miR-21之间的调控机制，为OSCC的早期标记物的筛选及发生进展机制提供了新的理论依据。