MBNL2 enhances cisplatin resistance by regulating apoptosis in ovarian cancer cells.

Although cisplatin is an effective anticancer agent for treating ovarian cancer, it encounters significant resistance. A full understanding of the mechanisms behind cisplatin resistance has not been achieved. This study identifies MBNL2 as a crucial regulator of cellular responses to cisplatin, examining variations in gene expression and methylation profiles between cisplatinsensitive and -resistant ovarian cancer cells. Cells resistant to cisplatin exhibited increased MBNL2 mRNA expression and significant demethylation at promoter CpG sites. Treating ovarian cancer cell lines with a DNA demethylating agent significantly raised MBNL2 mRNA expression, indicating that epigenetic mechanisms involving DNA methylation control MBNL2 expression. Modulating MBNL2 levels altered the response to cisplatin through survival pathways that shield cells from cisplatin-induced apoptosis. Overexpressing MBNL2 enhanced resistance, while its depletion heightened cisplatin sensitivity. Furthermore, MBNL2 mRNA levels differed among patients based on their response to platinum-based chemotherapeutics. Patients resistant to these drugs had higher MBNL2 mRNA levels, effectively distinguishing them from those who were sensitive (AUC = 0.89, P = 0.0308). A meta-analysis of seventeen datasets confirmed that lower MBNL2 expression levels are associated with a better chemotherapy response and longer relapse-free survival. Conversely, higher MBNL2 expression levels correlated with increased recurrence rates and reduced survival. Thus, MBNL2 may serve as a promising prognostic and therapeutic target for overcoming cisplatin resistance. [BMB Reports 2025; 58(5): 224-231].