Project description:<p>BRCA1 mutations are a hallmark of hereditary ovarian cancer, strongly linked to deficiencies in homologous recombination (HR) DNA repair and impaired DNA replication fork protection. However, its roles in cancer progression beyond maintaining genomic integrity remain poorly understood. Through metabolomics approaches, we found BRCA1-deficiency strikingly increased choline metabolism. Loss of BRCA1 promotes choline uptake through upregulating choline transporter-like protein 4 (CTL4). BRCA1 directly binds and recruits EZH2-mediated H3K27Me3 deposition to CTL4 promoter. CTL4 was therefore overexpressed in ovarian cancer tissues with BRCA1 mutations. Furthermore, BRCA1-deficiency significantly promotes ovarian cancer invasion, while inhibition of CTL4 reverses the high metastatic potential of BRCA1-deficient ovarian cancer cells, suggesting the functionality and specificity of CTL4 as a therapeutic target. Additionally, we discovered that phosphocholine, the choline metabolite increased by CTL4 overexpression, interacted with and stabilized the epithelial-to-mesenchymal transition inducer FAM3C in BRCA1-deficient ovarian cancer cells. Importantly, we identified a potent CTL4 inhibitor, DT-13, which significantly reduces choline metabolism and effectively suppresses metastasis in BRCA1-deficient ovarian cancers. Therefore, our study uncovers a mechanism underlying metastasis in BRCA1-deficient cancers and identifies CTL4 as a therapeutic target for metastatic ovarian cancer patients with BRCA1 mutations.</p>
Project description:Heredity is a major cause of ovarian cancer. Lynch syndrome is associated with 10-12% risk of ovarian cancer, diagnosis at young age and a predilection for endometrioid and clear cell tumors. Global gene expression profiling applied to 25 Lynch syndrome-associated and 42 sporadic ovarian cancers revealed 335 differentially expressed genes and involvement of the mTOR and the MAPK/ERK pathways. The clear cell tumors had distinct expression profiles with upregulation of HER2 and apoptosis signaling pathways. The distinct expression profiles provide clues relevant for hereditary tumorigenesis and may be relevant for therapeutic strategies and refined diagnostics in ovarian cancer linked to Lynch syndrome. Ovarian cancers linked to Lynch syndrome (n=25) were compared to a matched series of sporadic ovarian cancers (n=42), selected from a population-based consecutive series in which hereditary was excluded based on family history, normal MMR protein staining and lack of mutations in BRCA1 and BRCA2.