Abstract 472: Long non-coding RNA MIR31HG-derived circRNA enhances the oncogenicity of oral carcinoma

Abstract Introduction: Oral carcinoma (OC) represents a significant health challenge, with the role of non-coding RNAs, particularly microRNAs and long non-coding RNAs (LncRNAs), being well-established in its progression. However, the implications of circular RNAs (circRNAs) in this context are less well understood, presenting a notable gap in current research. Our study focuses on the MIR31HG LncRNA, identified as crucial in OC, particularly its role in producing circRNA, as evidenced by sequencing. This specific MIR31HG-derived circRNA, designated 31HGcircR, which contains a potential open reading frame (ORF), and may demonstrate phenotypic significances. Alterations to 31HGcircR, either through knockout or ORF mutation, result in remarkable phenotypic changes, highlighting its potential importance in the pathogenesis of OC. Methods: We implemented 31HGcircR overexpression in OC cell lines, utilizing the TetOff system for gene expression control. CRISPR/Cas9 was employed for gene knockout, and siRNA for gene knockdown. Gene expression was quantified using qPCR. Additionally, the BaseScope assay was used to label and detect the spatial expression of overexpressed 31HGcircR within the cells. Assays to assess cell proliferation, invasion, migration, anchorage-independent growth (AIG), and clonogenicity were conducted. Results: The findings revealed specific junctions of 31HGcircR and varied expression levels across different OC cell lines. There was a significant correlation among the expression of 31HGcircR, MIR31HG and miR-31-5p. Notably, the knockdown of 31HGcircR led to pronounced inhibition of cell growth, migration, invasion, AIG, and clonogenic activity. Conversely, overexpression of 31HGcircR or its ORFs augmented invasion and clonogenic potential in certain cell lines. The TetOff system demonstrated that minimal concentrations of Doxycycline effectively suppressed 31HGcircR expression, with reversible effects upon removal. Knocking out 31HGcircR resulted in reduced invasion and clonogenic capabilities. Conclusion: This study provides clues demonstrating the oncogenic roles of 31HGcircR in OC, which simulate the functions of MIR31HG or miR-31-5p. The changes in cell phenotypes following 31HGcircR manipulation suggest its potential as a therapeutic target or biomarker in OC. These findings offer valuable insights, contributing to the evolving understanding of circRNAs in cancer research and potential treatment avenues. Citation Format: Chung-Hsien Chou, Hsi-Feng Tu, Kuo-Wei Chang, Shu-Chun Lin. Long non-coding RNA MIR31HG-derived circRNA enhances the oncogenicity of oral carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 472.