FDXR Drives Primary and Endocrine Resistant Tumor Cell Growth in ER+ Breast Cancer via CPT1A-Mediated Fatty Acid Oxidation

The majority of breast cancers (BCs) harboring estrogen receptor (ER) have shown endocrine resistance. Our previous study has demonstrated that ferredoxin reductase (FDXR) promotes mitochondrial function and ER+ breast tumorigenesis. Here, integrative analyses of targeted metabolomics assay and gene expression profiling show that FDXR potentiates fatty acid oxidation (FAO) through positive regulation of carnitine palmitoyltransferase 1A (CPT1A) expression. Treatment with ER antagonist (tamoxifen) or degrader (fulvestrant) leads to increased expression of FDXR and CPT1A. In line with this finding, we find that FDXR-CPT1A-FAO axis is required for primary and endocrine resistant breast cancer cell growth. Therapeutically,combining endocrine therapy with FAO inhibitor synergistically reduces primary and endocrine resistant breast cancer cell growth, thus providing a potential combinatory treatment for ER+ breast cancer. We used microarrays to be able to elucidate to some extent the gene regulatory mechanisms of FDXR regulating breast cancer metabolism. T47D cells were infected with a retrovirus encoding the shRNA of FDXR(FDXR sh434) or control vector (Vec).