Project description:Metabolic reprogramming is a hallmark of cancer. Herein we discover that the key glycolytic enzyme pyruvate kinase M2 isoform (PKM2), but not the related isoform PKM1, is methylated by co-activator-associated arginine methyltransferase 1 (CARM1). PKM2 methylation reversibly shifts the balance of metabolism from oxidative phosphorylation to aerobic glycolysis in breast cancer cells. Oxidative phosphorylation depends on mitochondrial calcium concentration, which becomes critical for cancer cell survival when PKM2 methylation is blocked. By interacting with and suppressing the expression of inositol-1,4,5-trisphosphate receptors (InsP3Rs), methylated PKM2 inhibits the influx of calcium from the endoplasmic reticulum to mitochondria. Inhibiting PKM2 methylation with a competitive peptide delivered by nanoparticles perturbs the metabolic energy balance in cancer cells, leading to a decrease in cell proliferation, migration and metastasis. Collectively, the CARM1-PKM2 axis serves as a metabolic reprogramming mechanism in tumorigenesis, and inhibiting PKM2 methylation generates metabolic vulnerability to InsP3R-dependent mitochondrial functions.
Project description:Background Breast cancer is the leading cause of cancer related deaths in women. Triple negative breast cancers are highly aggressive, have an overall poor prognosis and has limited therapeutic options. Previously, we have identified an environmental induced gene mdig that predicted the overall survival in breast cancer patients and regulated breast cancer cell growth, motility and invasion partially through DNA and histone methylation. Mdig’s role in breast cancer growth and motility has been revealed however a comprehensive analysis of the proteomic profile of mdig affected cells in triple negative breast cancer has not been attempted yet. Methods We applied mass spectrometry technology featuring global proteomics and post translational modifications in triple negative breast cancer cells MDA-MB-231 that were deleted for mdig via CRISPR Cas 9 gene editing. Using label-free bottom up quantitative proteomics, we compared the proteomes of wildtype control (WT) and mdig knockout (KO) MDA-MB-231 cells and identified the proteins and pathways that are significantly altered with mdig deletion. Ingenuity Pathway Analysis (IPA) platform was further used to explore the signaling pathway networks with differentially expressed proteins and identified top canonical pathways, upstream regulators, and causal disease networks. Results 904 differentially expressed (p < 0.005) proteins were identified in MDA-MB-231 cells knocked out for mdig. Post-translational modification (PTM) analysis indicated that mdig loss reduced the abundance of oxidized histidine 39 of 60S ribosomal protein L27a (q = 0.00030) whereas global abundance of di-methylated lysine containing peptides was increased (p = 0.02). Relevance Our data provides the first insight towards the protein expression pattern in breast cancer associated with a complete disruption of the mdig gene. Differentially expressed proteins between WT and KO MDA-MB-231 triple negative breast cancer cells provided substantial information regarding the key proteins, biological process and pathways that are specifically upregulated in breast cancer tumorigenicity and invasiveness. Mdig affected signaling pathways and hub molecules will benefit for the development of novel treatment strategies for the development of breast cancer therapies.