Department of Genetics, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, 600 113, India.
Department of Health Research, Multi Disciplinary Research Unit (DHR-MRU), Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, 600 113, India.
Sci Rep. 2021 Apr 22;11(1):8808. doi: 10.1038/s41598-021-88161-3.
Tyrosine kinase inhibitor is an effective chemo-therapeutic drug against tumors with deregulated EGFR pathway. Recently, a genetic variant rs10251977 (G>A) in exon 20 of EGFR reported to act as a prognostic marker for HNSCC. Genotyping of this polymorphism in oral cancer patients showed a similar frequency in cases and controls. EGFR-AS1 expressed significantly high level in tumors and EGFR-A isoform expression showed significant positive correlation (r = 0.6464, p < 0.0001) with reference to EGFR-AS1 expression levels, consistent with larger TCGA HNSCC tumor dataset. Our bioinformatic analysis showed enrichment of alternative splicing marks H3K36me3 and presence of intronic polyA sites spanning around exon 15a and 15b of EGFR facilitates skipping of exon 15b, thereby promoting the splicing of EGFR-A isoform. In addition, high level expression of PTBP1 and its binding site in EGFR and EGFR-AS1 enhances the expression of EGFR-A isoform (r = 0.7404, p < 0.0001) suggesting that EGFR-AS1 expression modulates the EGFR-A and D isoforms through alternative splicing. In addition, this polymorphism creates a binding site for miR-891b in EGFR-AS1 and may negatively regulate the EGFR-A. Collectively, our results suggested the presence of genetic variant in EGFR-AS1 modulates the expression of EGFR-D and A isoforms.
酪氨酸激酶抑制剂是一种针对 EGFR 通路失调的肿瘤的有效化疗药物。最近,EGFR 外显子 20 中的遗传变异 rs10251977(G>A)被报道可作为头颈部鳞状细胞癌(HNSCC)的预后标志物。在口腔癌患者中对该多态性的基因分型表明,病例和对照之间的频率相似。在肿瘤中,EGFR-AS1 表达水平显著升高,并且 EGFR-A 异构体的表达与 EGFR-AS1 表达水平呈显著正相关(r=0.6464,p<0.0001),与更大的 TCGA HNSCC 肿瘤数据集一致。我们的生物信息学分析显示,替代剪接标记 H3K36me3 的富集以及 EGFR 中外显子 15a 和 15b 周围存在内含子多 A 位点,促进了外显子 15b 的跳过,从而促进了 EGFR-A 异构体的剪接。此外,PTBP1 的高表达及其在 EGFR 和 EGFR-AS1 中的结合位点增强了 EGFR-A 异构体的表达(r=0.7404,p<0.0001),表明 EGFR-AS1 表达通过选择性剪接调节 EGFR-A 和 D 异构体的表达。此外,该多态性在 EGFR-AS1 中创建了一个 miR-891b 的结合位点,可能负调控 EGFR-A。总之,我们的结果表明 EGFR-AS1 中的遗传变异存在可调节 EGFR-D 和 A 异构体的表达。