Lab No. 213, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh, India.
Department of Genetic and Genome Sciences, University of Connecticut Health Centre, Farmington, CT, USA.
Lab Invest. 2020 Dec;100(12):1589-1601. doi: 10.1038/s41374-020-0466-8. Epub 2020 Jul 15.
The deregulation of splicing factors and alternative splicing are increasingly viewed as major contributory factors in tumorigenesis. In this study, we report overexpression of a key splicing factor, heterogeneous nuclear ribonucleoprotein A2B1 (HNRNPA2B1), and thereby misregulation of alternative splicing, which is associated with the poor prognosis of head and neck cancer (HNC). The role of HNRNPA2B1 in HNC tumorigenesis via deregulation of alternative splicing is not well understood. Here, we found that the CRISPR/Cas9-mediated knockout of HNRNPA2B1 results in inhibition of HNC cells growth via the misregulation of alternative splicing of MST1R, WWOX, and CFLAR. We investigated the mechanism of HNRNPA2B1-mediated HNC cells growth and found that HNRNPA2B1 plays an important role in the alternative splicing of a proto-oncogene, macrophage stimulating 1 receptor (MST1R), which encodes for the recepteur d'origine nantais (RON), a receptor tyrosine kinase. Our results indicate that HNRNPA2B1 mediates the exclusion of cassette exon 11 from MST1R, resulting in the generation of RON∆165 isoform, which was found to be associated with the activation of Akt/PKB signaling in HNC cells. Using the MST1R-minigene model, we validated the role of HNRNPA2B1 in the generation of RON∆165 isoform. The depletion of HNRNPA2B1 results in the inclusion of exon 11, thereby reduction of RON∆165 isoform. The decrease of RON∆165 isoform causes inhibition of Akt/PKB signaling, which results in the upregulation of E-cadherin and downregulation of vimentin leading to the reduced epithelial-to-mesenchymal transition. The overexpression of HNRNPA2B1 in HNRNPA2B1 knockout cells rescues the expression of the RON∆165 isoform and leads to activation of Akt/PKB signaling and induces epithelial-to-mesenchymal transition in HNC cells. In summary, our study identifies HNRNPA2B1 as a putative oncogene in HNC that promotes Akt/PKB signaling via upregulation of RON∆165 isoform and promotes epithelial to mesenchymal transition in head and neck cancer cells.
剪接因子的失调和选择性剪接越来越被认为是肿瘤发生的主要因素。在这项研究中，我们报告了关键剪接因子异质核核糖核蛋白 A2B1（HNRNPA2B1）的过表达，以及由此导致的选择性剪接失调，这与头颈部癌症（HNC）的预后不良有关。HNRNPA2B1 通过调节选择性剪接在 HNC 肿瘤发生中的作用尚不清楚。在这里，我们发现 CRISPR/Cas9 介导的 HNRNPA2B1 敲除通过调节 MST1R、WWOX 和 CFLAR 的选择性剪接，导致 HNC 细胞生长受到抑制。我们研究了 HNRNPA2B1 介导的 HNC 细胞生长的机制，发现 HNRNPA2B1 在原癌基因巨噬细胞刺激 1 受体（MST1R）的选择性剪接中发挥重要作用，该基因编码 recepteur d'origine nantais（RON），一种受体酪氨酸激酶。我们的结果表明，HNRNPA2B1 介导 MST1R 外显子 11 的排除，导致 RON∆165 异构体的产生，RON∆165 异构体与 HNC 细胞中 Akt/PKB 信号的激活有关。使用 MST1R 迷你基因模型，我们验证了 HNRNPA2B1 在 RON∆165 异构体产生中的作用。HNRNPA2B1 的耗竭导致外显子 11 的包含，从而减少 RON∆165 异构体。RON∆165 异构体的减少导致 Akt/PKB 信号的抑制，导致 E-钙粘蛋白的上调和波形蛋白的下调，从而减少上皮-间充质转化。HNRNPA2B1 在 HNRNPA2B1 敲除细胞中的过表达挽救了 RON∆165 异构体的表达，并导致 Akt/PKB 信号的激活，并诱导 HNC 细胞的上皮-间充质转化。总之，我们的研究确定 HNRNPA2B1 是 HNC 中的一个推定癌基因，通过上调 RON∆165 异构体促进 Akt/PKB 信号，并促进头颈部癌细胞的上皮-间充质转化。
