Exosomes and their distinct integrins transfer the characteristics of oxaliplatin- and 5-FU-resistant behaviors in colorectal cancer cells.

backgroundExosomes are communication carriers and suitable biomarker candidates due to their cargoes with specific dynamic profiles. Integrins, as valuable prognostic markers in cancer, have importance in exosome-cell interaction. However, the role of exosome integrins in chemoresistant colorectal cancer remained unclear.

methodsOxaliplatin- and 5-FU-resistant cells (OXR and FUR) were established from human HCT-116 cells of colorectal cancer. Exosomes were collected from untreated and treated cells with oxaliplatin or 5-FU. Exosomes were isolated via ultracentrifugation and characterized using DLS and electron microscopy to evaluate size and morphology. Western blot analysis was employed to identify exosomal markers. The effects of exosomes on parental cells were examined using various methods, including MTT assay for proliferation, wound healing assay for migration, flow cytometry for cell cycle and apoptosis analysis, Matrigel-coated transwell inserts for invasion, and western blot for integrin expression evaluation.

resultsExosome integrins determine resistance behaviors in cells. We observed that exosomes from OXR cells or OXR cells treated with oxaliplatin increased ITGβ3 expression and decreased ITGβ4 expression in parental cells, resulting in distinct resistance behaviors. Exosomes from FUR cells or FUR cells treated with 5-FU reduced ITGβ4 levels and elevated ITGαv levels in parental cells, leading to varying degrees of invasive resistance behaviors. These findings suggest that exosome integrins may affect these behaviors. High ITGβ3 exosomes induced oxaliplatin resistance behaviors in parental cells. Lowering ITGβ3 levels in these exosomes inhibited the resistance behaviors observed in these cells. FUR exosomes that overexpressed ITGαv or ITGβ4 resulted in invasive 5-FU resistance behaviors in parental cells. A reduction in these exosome integrin levels led to moderate invasive behaviors. The decrease of ITGβ4 in FUR cell exosomes inhibited resistant migration and proliferation in parental cells. A twofold reduction of ITGαv in FUR cell exosomes resulted in a threefold decrease in invasion and inhibited migration in parental cells compared to those treated with high ITGαv exosomes.

conclusionOur findings reveal that, despite discrepancies between cellular integrin patterns and cellular behaviors, the levels of exosomal ITGβ3, ITGαv, or ITGβ4 could serve as potential diagnostic and therapeutic markers for resistance to oxaliplatin and 5-FU in future cancer treatments.