OT17 a novel microsatellite stable colorectal cancer cell line and organoid model for investigating mutant tumorigenesis and targeted therapeutics.

Human cancer cell lines serve as essential in vitro models for investigating tumor biology, carcinogenesis, molecular genetics, metastasis, and tumor evolution. In this study, we establish and characterize the OT17 cell line, derived from a moderately to poorly differentiated colorectal adenocarcinoma surgical specimen. Genetic analysis of OT17 revealed key mutations, including BRAF V600E, APC, and ERBB2, along with a deletion in TP53. Immunohistochemical profiling confirmed the expression of MLH1, MSH2, MSH6, and PMS2, indicating a microsatellite-stable (MSS) phenotype consistent with the primary tumor. The OT17 cell line demonstrated robust tumorigenicity in vivo, achieving a 100 % success rate in forming subcutaneous tumors in NOD-scid Il2rg(NSG)(NSG) mice. Additionally, a corresponding 3D organoid model (CO17) was established, which retained genetic concordance with OT17, further validating its relevance for preclinical applications. Together, the OT17 cell line and CO17 organoid system represent robust models for advancing colorectal cancer research, with potential applications in therapeutic screening, immunotherapy development, and MSS tumor biology studies.