BMAT1通过结合hnRNP-I调控TAZ可变剪接促进膀胱癌EMT的机制研究

Emerging evidence revealed that long noncoding RNA play important roles in epithelial-mesenchymal transition (EMT) process and metastasis of malignant diseases. In our pilot study, we identified a differentially expressed long noncoding RNA, here we termed BMAT1, in bladder cancer tissues using microarray analysis and showed that BMAT1 promotes EMT of bladder cancer. And we found that BMAT1 may bind to hnRNP-I and modulate alternative splicing of TAZ mRNA, yield. Here we proposed a novel hypothesis that long noncoding RNA BMAT1 promotes bladder cancer cells transition from a epithelial cell type to a mesenchymal cell type through binding to hnRNP-I and thus modulating alternative splicing of TAZ pre-mRNA, and ultimately promotes invasiveness and metastasis of bladder cancer cells. In the current study, we will further verify the role of BMAT1 in modulating molecular functions of hnRNP-I and alternative splicing of down-stream genes including TAZ, through in vitro and in vivo experiments, RNA immunoprecipitation and high throughput sequencing, functional reversal and rescue experiments. Success of this study will provide original scientific basis for BMAT1 and down-stream target genes acting as novel candidates for targeted therapy.

研究表明，长链非编码RNA参与恶性肿瘤上皮-间质转化（EMT）和转移过程的调控。我们课题组通过基因芯片筛选在膀胱癌组织中鉴定了差异表达长链非编码RNA BMAT1，并证明BMAT1具有促进膀胱癌EMT作用。进一步实验提示BMAT1可通过结合hnRNP-I蛋白，介导TAZ mRNA可变剪接，产生不同的剪接体。由此，我们提出长链非编码RNA调控膀胱癌转移机制的新假说，即“BMAT1通过影响hnRNP-I对TAZ 等pre-mRNA的剪接调控，促进细胞由上皮型向间质型转化，进而促进细胞侵袭和转移”。本研究拟进一步采用体内外实验，RNA免疫沉淀和高通量测序等技术，获得BMAT1与hnRNP-I直接相互作用的实验证据，并通过功能逆转实验、挽救实验等方法，获得BMAT1通过影响hnRNP-I功能进而调控TAZ等基因可变剪接的可靠证据，为BMAT1及下游通路作为靶向治疗的新靶点提供更充分的科学依据。

本研究表明上皮-间质转化（EMT）的发生与恶性肿瘤的浸润及远处转移密切相关，长链非编码RNA的表达异常在恶性肿瘤EMT的过程中发挥着重要调控作用。我们前期通过高通量测序鉴定了在膀胱癌肿瘤组织及癌旁组织中差异表达的长链非编码RNA BMAT1。体内外实验证实BMAT1过表达可促进膀胱癌细胞发生EMT及转移。进一步RNA pulldown、RNA免疫沉淀、高通量测序、功能逆转实验、挽救实验等获得“BMAT1通过与hnRNP-I结合，介导hnRNP-I调控TAZ的可变剪接，诱导膀胱癌细胞的EMT，从而促进膀胱癌的侵袭转移”的可靠证据，并分析了BMAT1与膀胱癌临床病理特征的关系，为BMAT1作为膀胱癌转移的分子标记物及靶向治疗的新靶点提供充分的科学依据。