Patients with TNBC can benefit significantly from earlier diagnosis/prognosis, targeted therapy, and predictive biomarker panels for optimal therapy. However, currently there are no clinically accepted markers for the prognosis of TN BCa and to predict its potential to metastasize. Although genomics and to some extent proteomic approaches have been used to address this gap in knowledge, these studies have resulted in limited success. Mitochondria are the only organelles, besides the nucleus, that contain their own DNA (mtDNA). mtDNA is highly susceptible to mutations due to lack of protective histones and increased exposure to reactive oxygen species (ROS). A recent study reported that the tumor cells with depleted mtDNA are having delayed tumor growth. Similarly, when mitochondrial DNA (mtDNA)-depleted tumor cells (?0 cells) were injected into mice, they enhanced their tumor growth property by acquisition of mtDNA from the host mouse cells and reassembling a mitochondrial electron transport chain complex (ETC) and respiratory function. Recent analysis of TCGA data suggested that `TCA Cycle and ETC gene sets' were the most frequently correlated gene sets to mtDNA copy number. Other one of the top correlated gene set was related mitochondrial Fatty Acid ?- Oxidation (FAO). These observations suggest that, at least in selected subgroups of cancers, mitochondrial biogenesis is important for their oncogenesis and tumor progression. PI lab recently discovered that mitochondrial reprogramming to FAO is critical in TNBC progression. Also, c-Src, FAO regulates one of the frequently activated oncopathways in TNBC by its autophosphorylation at Y419. We discovered that in Src activated TNBC, mitochondrial OXPHOS is enhanced. Src is also known to regulate several ETC proteins via its phosphorylation. Importantly, knockdown of FAO rate-limiting proteins carnitine palmitoyltransferase I (CPT1) or 2 (CPT2) abolished Src (Y419) autophosphorylation and that TNBC metastatic properties. This proposal aim to understand the role of mtDNA copy number in FAO reprogrammed TNBC and Src signature. We currently have 67 TNBC and 65 adjacent benign tissues with metabolomic, genomic and clinical follow-up information. mtDNA copy number will be analyzed in these tumors and adjacent tissues. Further bioinformatic analysis will focus on the significance of copy number in already available FAO, Src signature and metastatic potential of these tumors. This information will be critical for future larger studies to establish mtDNA copy number as a prognostic marker for TNBC that has metastatic potential driven by Src cancer pathway. We have assembled an excellent team of collaborators to work on this project including experts in mitochondrial genetics, TNBC progression, metabolomics, and bioinformatics, who are excited to work with us on these proposed studies.
We discovered the critical role of mitochondrial reprogramming to fatty acid oxidation in cancer pathway regulation. This project understands the significance of mitochondrial DNA copy number between benign and triple negative breast cancer as well as its significance in fatty acid oxidation. Using DNA from cancer and benign tissues and already available data from different OMICs approaches, this project aims to understand the relevance of mitochondria in triple negative breast cancer metastasis.
