Abstract B022: Metallothionein 2A loss shifts mitochondrial function and metabolism in high-grade serous ovarian cancer

Abstract Approximately 70% of high-grade serous ovarian cancer (HGSOC) cases exhibit a copy number loss in the genomic region encoding Metallothionein 2A (MT2A). MT2A is the most highly expressed of eleven coding genes of the Metallothionein (MT) proteins. MT proteins are small, cysteine-rich proteins known to chelate heavy metals. MT proteins are predominantly bound to zinc, which is essential for the catalytic activity of over 300 enzymes, including key enzymes involved in mitochondrial metabolism. While MT proteins have been linked to oncogenesis, the precise role of MT2A loss on mitochondrial function and cancer cell metabolism remains poorly understood. This gap is particularly critical given the essential role of mitochondrial function and metabolism in tumor growth. In this study, we investigate the consequences of MT2A loss on mitochondrial dynamics and metabolic pathways in HGSOC. We hypothesize that the loss of MT2A shifts mitochondrial function and metabolism in HGSOC, contributing to phenotypes associated with tumor progression. To explore this, MT2A expression levels were adjusted in CAOV3 HGSOC cells via lentiviral shRNA knockdown (KD). KD was confirmed transcriptionally via RT-qPCR and functionally using a nuclei-counting viability assay, which assesses sensitivity to cadmium chloride (CdCl2), a cytotoxic heavy metal. Mitochondrial membrane potential (MMP) was assessed via flow cytometry, and oxygen consumption rate (OCR) was measured with Resipher technology. Clonogenic potential was evaluated by soft agar colony formation assays. MT2A KD cells showed a significant decrease in nuclei count in response to CdCl2. MMP was reduced in MT2A KD cells, indicating compromised mitochondrial integrity with loss of MT2A. OCR was significantly decreased in MT2A KD cells, suggesting impaired oxidative phosphorylation with MT2A loss. These phenotypes decreased MMP and oxidative phosphorylation, are characteristic features of the Warburg effect, which is a hallmark of aggressive cancers. Soft agar assays revealed that MT2A loss significantly enhanced the cell’s ability to multiply adhesion free from a single cell which is a phenotype associated with aggressive oncogenic transformation. In summary, MT2A loss disrupts mitochondrial dynamics and oxidative metabolism while promoting traits associated with tumor aggressiveness. These findings support our hypothesis that MT2A plays a key role in regulating mitochondrial homeostasis and may influence metabolic adaptation in HGSOC. Citation Format: Mirna Mina-Abouda, M.S., Della Evans, B.S., Joe Delaney, Ph.D.. Metallothionein 2A loss shifts mitochondrial function and metabolism in high-grade serous ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr B022.