FOLFOXIRI Resistance Induction and Characterization in Human Colorectal Cancer Cells

SIMPLE SUMMARY: We created colorectal cancer in vitro models to study how an induced drug resistance profile can alter cell response and sensitivity to a treatment. By chronically exposing the cells to current first-line treatments (5-FU+folinic acid+oxaliplatin+SN38), resistance to the chemotherapy was obtained. We further investigated the mechanism underlying the acquired chemoresistance and highlighted the main up- and downregulated genes implicated. We also showed that optimized drug combination composed of tyrosine kinase inhibitors overcome chemotherapy-induced resistance. ABSTRACT: FOLFOXIRI, i.e., the combination of folinic acid, 5-fluorouracil, oxaliplatin, and irinotecan, is a first-line treatment for colorectal carcinoma (CRC), yet non-personalized and aggressive. In this study, to mimic the clinical situation of patients diagnosed with advanced CRC and exposed to a chronic treatment with FOLFOXIRI, we have generated the CRC cell clones chronically treated with FOLFOXIRI. A significant loss in sensitivity to FOLFOXIRI was obtained in all four cell lines, compared to their treatment-naïve calls, as shown in 2D cultures and heterotypic 3D co-cultures. Acquired drug resistance induction was observed through morphometric changes in terms of the organization of the actin filament. Bulk RNA sequencing revealed important upregulation of glucose transporter family 5 (GLUT5) in SW620 resistant cell line, while in the LS174T-resistant cell line, a significant downregulation of protein tyrosine phosphatase receptor S (PTPRS) and oxoglutarate dehydrogenase-like gene (OGDHL). This acquired resistance to FOLFOXIRI was overcome with optimized low-dose synergistic drug combinations (ODCs) acting via the Ras-Raf-MEK-ERK pathway. The ODCs inhibited the cell metabolic activity in SW620 and LS174T 3Dcc, respectively by up to 82%.