ObjectiveTo investigate whether lncRNA SOX2-OT inhibits the proliferation and migration of colorectal cancer (CRC) HCT-116 cells by regulating the miR-215-5p/NIN/RPN12 binding protein 1 homolog (NOB1) signaling pathway.MethodsCancerous and paired adjacent tissue samples from 29 CRC patients treated at Wuhan Jinyintan Hospital from June 2022 to May 2024 were collected, along with CRC cell lines (SW480, HCT-116, HP116, and LoVo) and normal human colon epithelial HCoApiC cells. The mRNA expression levels of SOX2-OT, miR-215-5p, and NOB1 in CRC tissues and cells were measured using qPCR method. HCT-116 cells were transfected with SOX2-OT knockdown or overexpression plasmids and corresponding negative control plasmids using RNA interference technology, dividing the cells into control group, si-NC group, si-SOX2-OT group, si-SOX2-OT + inhibitor (Inh) NC group, si-SOX2-OT + miR-215-5p Inh group, si-SOX2-OT + oe-NC group, and si-SOX2-OT + oe-NOB1 group. The mRNA expression levels of SOX2-OT, miR-215-5p, and NOB1 in each group of cells were detected using qPCR method. MTT assay, scratch wound healing assay, Transwell chamber assay, and flow cytometry were used to measure cell proliferation, migration, invasion, and apoptosis, respectively. Western blot was applied to detect protein expression levels of E-cadherin, N-cadherin, vimentin, Bcl-2, BAX, PCNA, MMP-9, and NOB1. The targeting relationship between miR-215-5p and SOX2-OT or NOB1 was validated using dualluciferase reporter gene assays.ResultsSOX2-OT and NOB1 mRNA were significantly upregulated, while miR-215-5p was downregulated in both CRC tissues and cells (all P < 0.05). In HCT-116 cells with SOX2-OT knockdown, the expression of SOX2-OT and NOB1 mRNA, cell proliferation, wound healing rate, invasive cell number, and protein levels of N-cadherin, vimentin, Bcl-2, NOB1, PCNA, and MMP-9 were significantly reduced (all P < 0.05), while miR-215-5p expression, apoptosis rate, and protein levels of E-cadherin and BAX were significantly increased (all P < 0.05). Both miR-215-5p knockdown and NOB1 overexpression reversed the inhibitory effects of SOX2-OT knockdown on HCT-116 cells (both P < 0.05). miR-215-5p was validated to target SOX2-OT and NOB1.ConclusionSOX2-OT knockdown upregulates miR-215-5p expression and downregulates NOB1 expression, further inhibiting the proliferation, migration, and invasion of HCT-116 cells and promoting apoptosis.