Jenkins, Brenita C.

Abstract During aging, muscle gradually undergoes sarcopenia, the loss of function associated with loss of mass, strength, endurance, and oxidative capacity. However, the 3D structural alterations of mitochondria associated with aging in skeletal muscle and cardiac tissues are not well described. Although mitochondrial aging is associated with decreased mitochondrial capacity, the genes responsible for the morphological changes in mitochondria during aging are poorly characterized. We measured changes in mitochondrial morphology in aged murine gastrocnemius, soleus, and cardiac tissues using serial block‐face scanning electron microscopy and 3D reconstructions. We also used reverse transcriptase‐quantitative PCR, transmission electron microscopy quantification, Seahorse analysis, and metabolomics and lipidomics to measure changes in mitochondrial morphology and function after loss of mitochondria contact site and cristae organizing system (MICOS) complex genes, Chchd3 , Chchd6 , and Mitofilin . We identified significant changes in mitochondrial size in aged murine gastrocnemius, soleus, and cardiac tissues. We found that both age‐related loss of the MICOS complex and knockouts of MICOS genes in mice altered mitochondrial morphology. Given the critical role of mitochondria in maintaining cellular metabolism, we characterized the metabolomes and lipidomes of young and aged mouse tissues, which showed profound alterations consistent with changes in membrane integrity, supporting our observations of age‐related changes in muscle tissues. We found a relationship between changes in the MICOS complex and aging. Thus, it is important to understand the mechanisms that underlie the tissue‐dependent 3D mitochondrial phenotypic changes that occur in aging and the evolutionary conservation of these mechanisms between Drosophila and mammals.

Abstract Ovarian cancer (OVCA) is the fifth leading cause of death in post-menopausal women in comparison to all other gynecologic malignancies. Late detection of OVCA is common as screening is done mostly in women over 63. This delay in screening coupled with poor prognosis presents the need for novel treatment measures. Repurposing of Metformin (Met), a biguanide used to increase insulin responses in the body, has been identified as a promising approach for therapeutic treatment in OVCA patients. The purpose of this study is to isolate metabolic pathways used by Met to alter OVCA onset. Preliminary results show that Met inhibits cell proliferation and clonogenic growth in both HeyA8 and HeyA8MDR which are drug-sensitive and drug-resistant cell lines, respectively. In combination with carboplatin, Met treatment enhanced chemosensitivity in both cell lines. In addition, lipidomic analysis was done to monitor the impact of lipid metabolites on OVCA cells. Our analysis showed differences in neutral lipid composition in drug-sensitive and resistant cells which indicates the role of various lipid species play in mediating drug-resistance. Furthermore, Met treatment triggered anti-cancerous pathways through syntheses of lipid metabolites. This data indicates that cell proliferation, along with clonogenic growth are inhibited dose dependently by Met treatment in drug-resistant and drug-sensitive cell lines. Chemosensitivity is enhanced by Met treatment in combination with carboplatin in HeyA8 and HeyA8MDR cell lines. Together, the data suggests that autophagy and lipid biogenesis can be altered through metabolic pathways by Met treatment. Through the use of repurposed Metformin, this approach shows promising results of a treatment regimen and potential prevention of OVCA. Citation Format: Brenita Colette Jenkins, Debarshi Roy, Kristal Maner-Smith, Viji Shridhar. Alterations in metformin mediated metabolism in chemoresistant ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2391.