Identification of MTFR1 as a Novel Prognostic Biomarker and Putative Oncogene for Breast Cancer: A Multi-Omics Analysis and in Vitro Experimental Validation.

Mitochondrial Fission Regulator 1 (MTFR1) plays a critical regulatory role in various malignancies; however, its specific function and clinical significance in breast cancer (BRCA) remain unexplored. This study systematically characterised MTFR1 by integrating multi-omics data, spatial transcriptomics, and single-cell sequencing, followed by in vitro experimental validation. MTFR1 was significantly overexpressed in BRCA tissues and predominantly localised to malignant cells. Functionally, MTFR1 was closely associated with cell cycle progression; in vitro knockdown significantly suppressed cell proliferation and induced cell cycle arrest. Clinically, high MTFR1 expression served as an independent predictor of poor prognosis and was linked to chemotherapy resistance. Cross-cancer immunotherapy analyses revealed that MTFR1 exhibited improved predictive performance for anti-PD-1 response during the on-treatment phase compared with pretreatment settings. This study elucidates the multidimensional role of MTFR1 as a putative oncogene in BRCA, highlighting it as a promising prognostic biomarker and therapeutic target.