Regulation of FN1 levels in endometrial cancer cells: Probiotics activate the p62-dependent autophagy-lysosome pathway to reduce tumor metastasis.

Endometrial cancer (EC) is a common female reproductive system malignancy, with metastasis being a major cause of poor prognosis. Intestinal flora imbalance is linked to gynecological tumor progression, and probiotics exhibit anti-tumor potential, but their regulatory mechanisms in EC migration/invasion/metastasis remain unclear. Bioinformatics analysis: TCGA database screened 1063 metastasis-related differentially expressed genes (DEGs), and 3915 DEGs after probiotic intervention, with 301 overlapping DEGs enriched in "ECM assembly", "autophagy regulation", and "epithelial migration" (GO analysis). GEPIA2 validated FOXA2, FN1, and CITED2 as survival-related genes in EC patients; STRING database identified p62 as a key FN1-interacting protein (interaction score=0.913). Cell experiments: Low-autophagy, high-FN1, highly invasive Ishikawa/KLE cells were selected. CCK-8 assay showed probiotic supernatant inhibited cell viability in a time/dose-dependent manner, with 1/32 and 1/64 dilutions chosen (based on IC50 values). qPCR/Western Blot confirmed probiotics downregulated FN1, upregulated p62 and LC3-II/LC3-I ratio (P < 0.01); Co-IP verified p62-FN1 interaction. p62 knockdown attenuated probiotic-induced FN1 degradation (P < 0.01), while p62 overexpression enhanced probiotics' inhibitory effect on EC cell migration/invasion (P < 0.001). Animal experiments: Nude mouse EC metastasis models showed significantly lower tumor fluorescence intensity in the probiotic intervention group (Vehicle+BS) than controls (P < 0.01). Western Blot revealed higher p62/LC3-II/LC3-I and lower FN1/N-cadherin in Vehicle + BS group (P < 0.01). Routine blood and liver/kidney function tests confirmed probiotic safety (P > 0.05). In conclusion, probiotics inhibit EC cell migration, invasion, and in vivo metastasis by activating autophagic flux and promoting p62-mediated autophagic degradation of FN1, with good safety, providing potential experimental evidence and target reference for clinical microecological adjuvant EC treatment.