G-quadruplex Structures in Dysregulated Long Non-Coding RNA of Ovarian Cancer and their Binding Interactions with Human Serum Albumin

Abstract

Ovarian carcinoma (OC) is a major cause of cancer-related mortality among women worldwide, with especially poor outcomes in resource-constrained regions. Long non-coding RNAs (lncRNAs) have emerged as critical players in OC progression, influencing drug resistance, metastasis, and other cellular processes. This study examines the potential of dysregulated lncRNAs in OC to form G-quadruplex (G4) structures. Using in silico predictions and experimental validation, we identified five lncRNAs ERLNC1, DLX6-AS1, LINC01127, FMNL1-DT, and LINP1 as candidates with a high propensity towards G4 formation. A combination of circular dichroism (CD) spectroscopy, Thioflavin T (ThT) fluorescence assay, Dot Blot assay, and reverse transcriptase stop assay, confirmed the ability of the lncRNAs to fold into stable G4 structures. Competitive DNA binding assays enabled the identification of essential G-tracts within each G4 motif highlighting the subtle differences in structure and stability of the different quadruplexes. Human serum albumin (HSA), a major circulatory protein, was found to interact with these G4-forming lncRNAs, albeit with different affinities and structural implications on the G4 motifs. This study provides the first detailed characterization of G4 structures in OC-dysregulated lncRNAs and elucidates their interactions with HSA. The G4 structures identified in these lncRNAs and their interaction with HSA can be of potential value for early OC diagnosis.