Mitochondria-mediated Epigenetic Transfer Between Chondrosarcoma and Wild-type Cells

Glioblastoma (GB), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), cholangiocarcinoma, and chondrosarcoma (CS) cancers all contain mutations in the gene isocitrate dehydrogenase 2 (IDH2). The mutant IDH2 enzyme exhibits transformation of alpha-ketoglutarate (αKG) into the oncometabolite D-2-hydroxyglutarate (D2HG) in the mitochondria of these cancers. Mitochondrial-mediated transfer between cancer cells and recipient cells is a significant event that impacts the physiology of the receiving cell, specifically the epigenetic landscape. Previous experiments indicating increased DNA methylation in mesenchymal stem cells exposed to IDH1 or IDH2 conditioned medium underscore the potential role of D2HG to alter methylation states. Additionally, the presence of nanotubular highways facilitating mitochondrial exchange between IDH2 mutant chondrosarcoma cells further motivates investigation into mitochondria-mediated epigenetic transfer. I hypothesize that mitochondria derived from IDH2-mutant chondrosarcoma cells are transferred to recipient normal lymphoblastoid B cells (N-LCL) primarily through tunneling nanotubes (TNTs), and that disruption of the actin cytoskeleton will inhibit this transfer. Secondly, the presence of D2HG generated in the mitochondria due to IDH2 mutations will lead to increased levels of mitochondrial DNA and RNA methylation. Cell physiology is expected to be affected by this genetic alteration in both host and recipient cells. Thirdly, transcriptional downregulation will be triggered by D2HG-mediated methylation of DNA and histones. My specific aims are 1) Quantify the exchange of mitochondria via nanotubular highways between IDH2 mutant cells and wild-type cells and control transfer via cytoskeletal inhibitors, 2) compare extent of variation of D2HG accumulation in mitochondria segregated from IDH mutant cells and wild-type chondrocytes and 3) characterize methylation patterns of mitochondrial DNA and RNA between mutant cells and wild-type counterparts. The experimental data acquired here will reveal a better understanding of the molecular mechanisms behind the progression of IDH2 cancers and make advancements in our understanding of intercellular communication in cancer biology.