Differential Expression of Long Non-coding Ribonucleic Acid (RNA) Genes in Endometriosis-associated Ovarian Cancer (EAOC): A Pilot Meta-analysis for Pathological Insights and Potential Diagnostic Biomarker Identification

Introduction: Endometrioid and clear cell carcinomas of the ovary are the most common subtypes of epithelial malignancy arising from endometriosis and are often termed endometriosis-associated ovarian carcinomas (EAOCs). There is a paucity of experimental evidence in the medical literature regarding the role of long non-coding ribonucleic acid (RNA) gene expression in the pathogenesis of these carcinomas. Purpose: There is a need to develop understanding of the pathogenesis of these carcinomas for neoplastic risk stratification in endometriosis and to develop novel diagnostic biomarkers. Clear cell carcinoma of the ovary, in particular, has a poor prognosis as a result of resistance to standard platinum-based chemotherapy. Methods: RNAseq datasets from EAOCs were downloaded from Gene Expression Omnibus (GEO) and compared with normal ovarian control sequences using a customized bioinformatic pipeline. Results: We found 88 differentially expressed non-coding RNA molecules present in both endometrioid and clear cell carcinoma types compared with controls. A further 117 were specifically differentially expressed in the endometrioid carcinoma group and 128 in clear cell carcinoma samples alone. Genes of interest for further study from the 88 shared set in both EAOC types include CASC9, RP4-561L24.3, SLC2A1-AS1, LUCAT1, XIST, CASC15, and MIR99AHG. These genes appear to influence ferroptosis as a common pathway. Conclusions: Alterations in the ferroptosis pathway may be a key event in development of EAOC in ovarian endometriosis patients. Further work is required to elucidate the function of the candidate RNA genes identified in this study by in-vitro, cell line and cultured organoid experiments. These candidate RNA gene biomarkers have potential clinical utility in early diagnosis, risk stratification of endometriosis, and post-surgical monitoring.