Transformer 2β regulates alternative splicing of cell cycle regulator genes to promote ovarian cancer cell progression

Poor prognosis of late stage ovarian cancer patients is observed with high metastasis rate, but the underlying molecular mechanism is ambiguous. RNA binding proteins (RBPs) play important roles in post-transcriptional regulation in tumor neoplasia and metastasis. In this study, we dedicated to explore the molecular functions of a canonical RBP, TRA2B, in cancer cells. By knocking TRA2B expression in HeLa cells and performing whole transcriptome sequencing experiment (RNA-seq), we found TRA2B-regulated alternative splicing profile was tightly associated with mitotic cell cycle, apoptosis, and several cancer pathways. Meanwhile, hundreds of genes were regulated by TRA2B at expression level, and their functions were enriched in cell proliferation, cell adhesion and angiogenesis, which were also related to cancer progression. We also observed the AS regulation and expression regulation were independent by integrating AS genes and expression changed genes. We then explored and validated the carcinogenic functions of TRA2B by knocking down its expression in ovarian cancer cells. In vivo, higher expression level of TRA2B was associated with poor prognosis in ovarian cancer patients. In conclusion, we demonstrated the important roles of TRA2B in ovarian cancer neoplasia and progression, and identified the underlying molecular mechanisms, making a contribution to molecular targeting treatment of ovarian cancer in the future. In this study, using next-generation RNA sequencing (RNA-seq) technology, we systematically investigated the global TRA2B-regulated AS events and the global gene expression change by silencing the expression of Tra2β in cancer cells. We found TRA2B could extensively regulate gene expression and AS in HeLa cells, which was highly related to its carcinogenic functions. Silencing experiment of TRA2B in ovarian cells validated its functions in cell proliferation, cell invasion and cell apoptosis in ovarian cancer cells. In summary, we extensively confirmed the carcinogenic functions of TRA2B in ovarian cancer cells, which were completed by regulating the expression and alternative splicing of associated genes.

晚期卵巢癌患者预后较差且转移率居高不下，但其潜在分子机制仍未明确。RNA结合蛋白（RNA binding proteins, RBPs）在肿瘤发生与转移的转录后调控中发挥关键作用。本研究旨在探讨经典RNA结合蛋白TRA2B在癌细胞中的分子功能。通过在HeLa细胞中敲低TRA2B的表达，并开展全转录组测序实验（whole transcriptome sequencing, RNA-seq），我们发现TRA2B调控的可变剪接（alternative splicing, AS）谱与细胞有丝分裂周期、细胞凋亡及多条癌症通路密切相关。与此同时，数百个基因的表达水平受TRA2B调控，这些基因的功能富集于细胞增殖、细胞黏附与血管生成等与癌症进展相关的生物学过程。进一步通过整合可变剪接差异基因与表达差异基因，我们发现TRA2B的可变剪接调控与基因表达调控彼此独立。随后，我们在卵巢癌细胞中敲低TRA2B的表达，对其致癌功能进行了探究与验证。体内实验结果显示，卵巢癌患者体内TRA2B高表达与不良预后显著相关。综上，本研究阐明了TRA2B在卵巢癌发生与进展中的重要作用，并揭示了其潜在分子机制，为未来卵巢癌的分子靶向治疗提供了理论支撑。
本研究借助下一代RNA测序（next-generation RNA sequencing, RNA-seq）技术，通过敲低癌细胞中Tra2β的表达，系统解析了TRA2B调控的全域可变剪接事件及全基因组基因表达变化。研究发现，TRA2B可广泛调控HeLa细胞中的基因表达与可变剪接，这与其致癌功能高度相关。在卵巢细胞中进行的TRA2B敲低实验验证了其在卵巢癌细胞中调控细胞增殖、侵袭与凋亡的功能。综上，本研究全面证实了TRA2B在卵巢癌细胞中的致癌功能，该功能通过调控相关基因的表达与可变剪接得以实现。