Loss of miR-16-1-3p Activity Predicts Chemoresistance and Progression in Osteosarcoma: An Integrative Clinicopathologic Study

Introduction Chemotherapy resistance contributes significantly to mortality in osteosarcoma (OS) patients. The role of miR-16, miR-16-1-3p, and miR-16-2-3p in modulating chemotherapy response and disease progression in OS remains unclear. Methods RNA-seq and clinical data from 82 OS patients in the TARGET-OS database were analyzed. Patients were classified by progression status (progressive disease [PD] vs. progression-free survivors [PFS]) and chemotherapy response (resistant vs. responsive). Target genes of the three miRNAs were predicted using TargetScan 7.2 and analyzed via Gene Set Enrichment Analysis (GSEA). Kaplan-Meier analysis was used to evaluate the prognostic value of cumulative Z-scores of enriched target gene sets. We used lentivirus to overexpress miRNAs in an osteosarcoma cell line to assess their effect on cisplatin sensitivity. Sensors of miR-16-1/2-3p activity were constructed. miR-16-1-3p-mediated biological effects were tested in vitro and in vivo. Results Overexpression of miR-16, miR-16-1-3p, and miR-16-2-3p sensitized OS cells to cisplatin. Predicted target genes of all three miRNAs were significantly enriched among genes upregulated in chemotherapy-resistant OS samples, suggesting reduced miRNA activity. Target genes of miR-16-1-3p were further enriched in PD cohort. High cumulative Z-scores of target gene sets correlated with poor survival. MiR-Sensor assays confirmed that miR-16-1-3p suppresses protein expression via target mRNA sequence recognition. Functional assays demonstrated significant tumor-suppressive effects of miR-16-1-3p in vitro and in vivo. Conclusion Reduced activities of miR-16, miR-16-1-3p, and miR-16-2-3p are linked to chemoresistance in OS, and only miR-16-1-3p activity loss correlates with disease progression. MiR-16-1-3p may serve as a biomarker for chemoresistance and prognosis in OS.