Gut microbiota metabolites drive osteosarcoma progression through JUP activation: a multi-omics mendelian randomization study.

Osteosarcoma exhibits high heterogeneity and lacks effective therapeutic targets. This study integrated Mendelian randomization, transcriptomics, and 16S rRNA sequencing to investigate potential associations between gut microbiota, metabolites, and osteosarcoma. Multi-omics analysis identified junction plakoglobin (JUP) as a candidate node gene. 16S rRNA sequencing revealed reduced abundance of bacteria belonging to the genus Lactobacillus in osteosarcoma patients. Based on database-derived associations from gutMGene, we selected a Lactobacillus-associated metabolite, 5-(3,4-dihydroxyphenyl)-valerolactone (DPV), for molecular docking analysis, which computationally predicted that DPV may bind JUP, though this finding remains to be experimentally validated. JUP expression positively correlated with M0 macrophage infiltration, suggesting a potential link to the immune microenvironment. To explore this axis experimentally, we established JUP-knockdown osteosarcoma cells and examined responses to Lactiplantibacillus plantarum and DPV. Both treatments significantly inhibited proliferation, colony formation, and invasion in JUP-expressing cells, whereas these effects were attenuated in JUP-knockdown cells, suggesting that JUP may play a role. Overall, this study provides a working hypothesis-generating framework linking gut microbiota, microbial metabolites, and JUP in osteosarcoma, presenting this connection as a testable hypothesis rather than an established biological axis. The multi-omics datasets were analyzed separately without formal integrative modeling; therefore, this study is exploratory and the findings should be interpreted as hypothesis-generating. These findings suggest directions for further investigation into microbiota-related strategies in osteosarcoma.