Departments of Pathology, Saint Louis University, Missouri, USA.
Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China.
J Biol Chem. 2022 May;298(5):101895. doi: 10.1016/j.jbc.2022.101895. Epub 2022 Apr 1.
Long noncoding RNAs (lncRNAs) have gained widespread attention as a new layer of regulation in biological processes during development and disease. The lncRNA ELDR (EGFR long noncoding downstream RNA) was recently shown to be highly expressed in oral cancers as compared to adjacent nontumor tissue, and we previously reported that ELDR may be an oncogene as inhibition of ELDR reduces tumor growth in oral cancer models. Furthermore, overexpression of ELDR induces proliferation and colony formation in normal oral keratinocytes (NOKs). In this study, we examined in further detail how ELDR drives the neoplastic transformation of normal keratinocytes. We performed RNA-seq analysis on NOKs stably expressing ELDR (NOK-ELDR), which revealed that ELDR enhances the expression of cell cycle-related genes. Expression of Aurora kinase A and its downstream targets Polo-like kinase 1, cell division cycle 25C, cyclin-dependent kinase 1, and cyclin B1 (CCNB1) are significantly increased in NOK-ELDR cells, suggesting induction of G2/M progression. We further identified CCCTC-binding factor (CTCF) as a binding partner of ELDR in NOK-ELDR cells. We show that ELDR stabilizes CTCF and increases its expression. Finally, we demonstrate the ELDR-CTCF axis upregulates transcription factor Forkhead box M1, which induces Aurora kinase A expression and downstream G2/M transition. These findings provide mechanistic insights into the role of the lncRNA ELDR as a potential driver of oral cancer during neoplastic transformation of normal keratinocytes.
长链非编码 RNA（lncRNA）作为发育和疾病过程中生物过程的新调控层，已引起广泛关注。最近发现，lncRNA ELDR（EGFR 长非编码下游 RNA）在口腔癌中的表达明显高于相邻非肿瘤组织，我们之前曾报道过 ELDR 可能是一种癌基因，因为抑制 ELDR 可减少口腔癌模型中的肿瘤生长。此外，ELDR 的过表达可诱导正常口腔角质细胞（NOK）的增殖和集落形成。在本研究中，我们进一步详细研究了 ELDR 如何驱动正常角质细胞的肿瘤转化。我们对稳定表达 ELDR 的 NOK（NOK-ELDR）进行了 RNA-seq 分析，结果表明 ELDR 增强了与细胞周期相关的基因表达。Aurora 激酶 A 及其下游靶标 Polo 样激酶 1、细胞分裂周期蛋白 25C、细胞周期蛋白依赖性激酶 1 和细胞周期蛋白 B1（CCNB1）在 NOK-ELDR 细胞中的表达显著增加，表明 G2/M 期进展受到诱导。我们进一步鉴定出 CCCTC 结合因子（CTCF）是 NOK-ELDR 细胞中 ELDR 的结合伴侣。我们表明 ELDR 稳定了 CTCF 并增加了其表达。最后，我们证明了 ELDR-CTCF 轴上调转录因子叉头框 M1，从而诱导 Aurora 激酶 A 的表达和下游 G2/M 转变。这些发现为 lncRNA ELDR 在正常角质细胞的肿瘤转化过程中作为口腔癌潜在驱动因子的作用提供了机制见解。
