Paradoxical prognosis of extracellular vesicle-derived miR-4435 expression in advanced colorectal cancer

Abstract Extracellular vesicle (EV)-derived microRNAs are promising non-invasive biomarkers for colorectal cancer (CRC), but their stage-specific prognostic significance remains unclear. We evaluated circulating EV-derived miR-4435 and its target TIMP3 in a retrospective cohort of 100 plasma samples (20 healthy controls and 80 CRC patients evenly distributed across stages 0–1, 2, 3, and 4). EVs were isolated, and miR-4435 and TIMP3 expression were quantified by real-time PCR. Patients were stratified into high- and low-expression groups using predefined cohort mean cutoffs, confirmed by median-cutoff sensitivity analysis. TIMP3 was significantly lower in CRC than in healthy controls, remaining significant after age adjustment; miR-4435 was also elevated in CRC, though attenuated after age adjustment. Stage-stratified survival analysis revealed a paradoxical, stage-dependent pattern for miR-4435: elevated expression was associated with significantly poorer recurrence-free survival and a non-significant trend toward poorer overall survival in early-stage CRC, but with significantly improved overall and recurrence-free survival in advanced-stage CRC, a pattern preserved under median-based stratification. TIMP3 was not significantly associated with survival at any stage. These findings suggest circulating EV-derived miR-4435 may have stage-dependent prognostic relevance, potentially reflecting tumor biology and tumor–host interactions across disease stages rather than indicating uniformly adverse prognosis.