Abstract 4822: Investigating the role of miR-27a-3p in the WNT signaling pathway in colorectal cancer stem cells

Abstract Cancer stem cell (CSC) overpopulation drives colorectal cancer (CRC) development and growth, but molecular mechanisms are unclear. CSCs functional phenotypic characteristics include signaling pathway dysregulation. CRC CSCs, in particular, are defined by their high WNT signaling activity, particularly those defined by the stem cell maker leucine-rich-repeat containing G protein-coupled receptor 5 (LGR5). A growing body of scientific evidence indicates that miRNAs, involved in post-transcriptional gene expression, play an important role in maintaining the CSC phenotype. However, the exact mechanism is still unknown. Our goal is to investigate how miRNAs contribute to the SC origin of CRC. My preliminary experiments used HT-29 CRC cells and NanoString profiling to identify miRNAs enriched in FACS-isolated CSCs. I discovered that miR-27a-3p is differentially upregulated in LGR5+ CSCs versus LGR5- cells. Analysis of available deep sequencing data also shows that the canonical miR-27a-3p is the highest expressed isoform in human CRC and is significantly upregulated during the colonic adenoma-carcinoma progression. miR-27a-3p has been shown to: i) be enriched in human CSCs in CRC utilizing other CSCs markers and methods; ii) activate or repress WNT signaling activity in various cancers; iii) increase chemoresistance in various cancers. The exact mechanism by which miR-27a-3p functions in CRC to regulate WNT signaling has not been elucidated. Hypothesis: miR-27a-3p is enriched in CRC and the LGR5+ SC subpopulation; miR-27a-3p promotes WNT signaling expression through repression of WNT antagonist targets. A significant increase in cellular proliferation was seen in the HT-29 stable lentiviral overexpressing cell line, and an increase in the WNT target genes mRNA of LGR, cMYC, cyclin D1, MET, and CD44. Decreases in LGR5, cMYC, cyclin D1, and MET were seen in the HCT116 stable lentiviral knockdown CRC cell line. My findings show that miR-27a-3p modulates WNT signaling in CRC cell lines by targeting WNT antagonistic targets that affect the stability and expression of β-catenin. Citation Format: Molly A. Lausten, Victoria A. Stark, Caroline O. Facey, Lynn M. Opdenaker, Bruce M. Boman. Investigating the role of miR-27a-3p in the WNT signaling pathway in colorectal cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 4822.