Integrated pan-cancer analysis and experimental verification of the roles of meiotic nuclear divisions 1 in breast cancer

Introduction: The aberrant up-regulation of meiotic nuclear division 1 (MND1) in somatic cells is considered as one of the driving factors of oncogenesis, whereas its expression and role in breast invasive cancer (BRCA) remain unclear. Hence, this study embarked on a comprehensive evaluation of MND1 across various cancers and identified its roles in BRCA. Methods: Based on publicly available databases, including but not limited to UCSC Xena, TCGA, GTEx, GEO, STRING, GeneMANIA, and CancerSEA, we evaluated the expression patterns, genomic features, and biological functions of MND1 from a pan-cancer viewpoint and delved into the implications of MND1 in the prognosis and treatment of BRCA. Further molecular biology experiments were undertaken to identify the role of MND1 in proliferation, migration, and apoptosis in BRCA cells. Results: Elevated levels of MND1 were notably observed in a wide array of tumor types, especially in BRCA, COAD, HNSC, LIHC, LUAD, LUSC, STAD, and UCEC. Elevated MND1 expression was markedly associated with shortened OS in several tumors, including BRCA (HR = 1.52 [95%CI, 1.10–2.09], P = 0.011). The up-regulation of MND1 in BRCA was validated in external cohorts and clinical samples. Survival analyses demonstrated that elevated MND1 expression was associated with decreased survival for patients with BRCA. Co-expressed genes of MND1 were identified, and subsequent pathway analyses based on significantly associated genes indicated that MND1 plays key roles in DNA replication, cell cycle regulation, and DNA damage repair. The observed abnormal elevation and activation of MND1 led to increased proliferation and migration, along with decreased apoptosis in BRCA cells. Conclusions: MND1 emerges as a promising biomarker for diagnostic and therapeutic targeting in various cancers, including BRCA. The abnormal up-regulation and activation of MND1 are linked to carcinogenesis and poor prognosis among BRCA patients, which may be attributed to its involvement in HR-dependent ALT, warranting further scrutiny.