C-X-C chemokine receptor family genes in osteosarcoma: expression profiles, regulatory networks, and functional impact on tumor progression.

In this comprehensive study, we explored the molecular landscape C-X-C chemokine receptor (CXCR) family genes (CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, and CXCR7) in osteosarcoma (OS) by scrutinizing the expression profiles and functional implications using Bioinformatics analyses and molecular experiments. We found significant up-regulation of these genes in OS cell lines compared to control cell lines, as assessed by RT-qPCR, with high diagnostic potential demonstrated by receiver operating characteristic (ROC) curve analysis. Cross-validation using the GSE12865 dataset revealed consistent up-regulation of CXCR family genes in OS samples, alongside decreased promoter methylation in tumor samples compared to normal tissues, as confirmed by the UALCAN database. Mutational analysis, conducted using data from 237 OS samples from the cBioPortal database, revealed minimal mutations in CXCR1 and CXCR2, with no alterations in CXCR3, CXCR4, CXCR5, and CXCR7. Copy number variation (CNV) analysis showed some level of amplification in CXCR1 and CXCR2, but no significant alterations in the copy numbers of the other genes. Survival analysis using meta-analysis across multiple independent studies showed that the expression of some CXCR genes were significantly associated with poor patient survival. Further exploration of the transcriptional regulation of CXCR genes using the ENCORI database revealed an intricate miRNA-mRNA network involving miR-130a, miR-146a, miR-155, miR-21, and miR-7, which regulate the expression of these genes. Elevated expression of these miRNAs in OS samples was validated by RT-qPCR, with promising diagnostic potential highlighted by ROC analysis. Additionally, the immunological analysis revealed a positive correlation between the expressions of CXCR genes and immune cell types, including macrophages and T cells, and CXCR genes were found to enhance drug responsiveness in OS patients. Gene enrichment analysis identified critical biological processes and pathways, such as chemokine-mediated signaling and immune response, linked to the CXCR family. Knockdown of CXCR1 in HOS and MG-63 cells confirmed that CXCR1 plays a crucial role in cell proliferation, colony formation, and migration. CXCR1 knockdown significantly reduced cell proliferation and colony formation, while enhancing cell migration, underscoring its functional importance in OS progression. Overall, our findings suggest that the CXCR family genes are potential diagnostic and prognostic markers in OS, with implications for therapeutic targeting and further investigation into their role in OS pathogenesis.