异常的可变剪接事件在癌症生物学中起着至关重要的作用。有助于肿瘤侵袭,转移,上皮-间质转化,和抗药性。最近的研究表明,选择性剪接是结直肠癌转录组变异的关键特征。在全球恶性肿瘤中,发病率和死亡率均排名第三。长链非编码RNA可以通过充当反式调节剂来调节这一过程,招募剪接因素,或者驱使他们去特定的目标基因。LncH19是一种在几种肿瘤类型中不调节的lncRNA,在结直肠癌中,它在肿瘤发病中起着至关重要的作用,programming,和转移。在本文中,我们发现,在结肠直肠癌细胞中,长链非编码RNAH19可以结合未成熟RNA和剪接因子如hnRNPM和RBFOX2。通过生物信息学分析,我们确定了57个与lncH19相关的转录本,并且含有两种剪接因子的结合位点,hnRNPM,RBFOX2在这些成绩单中,我们鉴定了GTPase-RAC1的mRNA,其选择性剪接的同工型,RAC1B,在恶性转化中被归因于几个角色。我们确认了,在体外,剪接因子与转录物RAC1和lncH19的结合。在两种结直肠癌细胞系(SW620和HCT116)中表达实验的损失和获得证明,lncH19是RAC1B表达所必需的,通过RAC1B,它诱导c-Myc和Cyclin-D增加。在体内,结直肠癌患者活检的调查显示,所有探索的基因水平较高(lncH19,RAC1B,c-Myc和Cyclin-D)关于健康的对应物,从而支持我们的体外模型。此外,我们发现结直肠癌患者中lncH19和RAC1B呈正相关.最后,我们证明了lncH19作为航天飞机,驱动剪接因子RBFOX2和hnRNPM到RAC1,允许外显子保留和RAC1B表达。本文显示的数据代表了一种新的作用机制的第一个证据,通过该机制,lncH19通过调节可变剪接来促进结直肠癌,从而发挥其作为癌基因的功能。
Aberrant alternative splicing events play a critical role in cancer biology, contributing to tumor invasion, metastasis, epithelial-mesenchymal transition, and drug resistance. Recent studies have shown that alternative splicing is a key feature for transcriptomic variations in colorectal cancer, which ranks third among malignant tumors worldwide in both incidence and mortality. Long non-coding RNAs can modulate this process by acting as trans-regulatory agents, recruiting splicing factors, or driving them to specific targeted genes. LncH19 is a lncRNA dis-regulated in several tumor types and, in colorectal cancer, it plays a critical role in tumor onset, progression, and metastasis. In this paper, we found, that in colorectal cancer cells, the long non-coding RNA H19 can bind immature RNAs and splicing factors as hnRNPM and RBFOX2. Through bioinformatic analysis, we identified 57 transcripts associated with lncH19 and containing binding sites for both splicing factors, hnRNPM, and RBFOX2. Among these transcripts, we identified the mRNA of the GTPase-
RAC1, whose alternatively spliced isoform, RAC1B, has been ascribed several roles in the malignant transformation. We confirmed, in vitro, the binding of the splicing factors to both the transcripts
RAC1 and lncH19. Loss and gain of expression experiments in two colorectal cancer cell lines (SW620 and HCT116) demonstrated that lncH19 is required for RAC1B expression and, through RAC1B, it induces c-Myc and Cyclin-D increase. In vivo, investigation from biopsies of colorectal cancer patients showed higher levels of all the explored genes (lncH19, RAC1B, c-Myc and Cyclin-D) concerning the healthy counterpart, thus supporting our in vitro model. In addition, we identified a positive correlation between lncH19 and RAC1B in colorectal cancer patients. Finally, we demonstrated that lncH19, as a shuttle, drives the splicing factors RBFOX2 and hnRNPM to
RAC1 allowing exon retention and RAC1B expression. The data shown in this paper represent the first evidence of a new mechanism of action by which lncH19 carries out its functions as an oncogene by prompting colorectal cancer through the modulation of alternative splicing.