Abstract 4417: Identification of signaling and apoptotic pathway alterations in oxaliplatin resistant HCT116 colorectal cancer cells

Abstract Background: Chemoresistance remains a significant barrier in colorectal cancer (CRC) treatment, particularly with oxaliplatin, a key first-line chemotherapy agent. This study is therefore aimed to develop an in vitro model of oxaliplatin-resistant HCT116 cells and investigate the associated morphological and molecular adaptations to identify potential dysregulated survival and apoptotic pathways that are playing a role in developing chemoresistance. Methods: HCT116 CRC cells were cultured, and resistance was induced by stepwise oxaliplatin exposure, with recovery phases between treatments. Morphological changes during resistance development were observed using phase-contrast microscopy. Flow cytometry was performed to analyze cell cycle distribution and apoptotic cell populations. Gene expression of key survival pathways, including Wnt/β-catenin, NFκB, and PI3K/Akt, was assessed using qPCR to identify molecular alterations associated with resistance. Results: Parental HCT116 cells displayed cuboidal morphology, high proliferation (Ki-67 positivity), and epithelial characteristics (moderate E-cadherin and ALDH1 expression). Resistant cells exhibited increased morphological heterogeneity, cell detachment, and features of epithelial-mesenchymal transition (EMT). Flow cytometry revealed a significant reduction in the sub-G1 population and an increase in the G2/M phase, suggesting diminished apoptosis and cell cycle dysregulation in oxaliplatin resistant HCT116 cells as compared to wild type. Gene expression analysis showed a marked upregulation of β-catenin, NFκB, and PI3K/Akt pathway components, coupled with increased expression of EMT markers (Snail, Vimentin) and drug efflux genes (ABCG2, ABCC1) in oxaliplatin resistant cells as compared to wild type HCT116 cells suggesting a role of these survival pathways and genes in induction of resistance. Conclusion: Oxaliplatin resistance in HCT116 CRC cells is characterized by morphological plasticity, altered cell cycle regulation, and activation of survival pathways, including Wnt/β-catenin, NFκB, and PI3K/Akt. These findings highlight the complexity of chemoresistance and provide a basis for identifying novel targets to enhance treatment efficacy in CRC. Citation Format: Aliza Jafri, Sheerien Rajput, Areeb Ahmed, Azhar Hussain Rajabali, Kulsoom Ghias. Identification of signaling and apoptotic pathway alterations in oxaliplatin resistant HCT116 colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4417.