Project description:Fumarylacetoacetate hydrolase (Fah), the last enzyme of the tyrosine degradation pathway, is specifically expressed in hepatocytes in the liver. Loss of Fah leads to liver failure in mice within 6-8 weeks. This can be prevented by blocking tyrosine degradation upstream of Fah with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC). Here, we investigate the impact of p21 on global gene expression in Fah deficiency. Experiment Overall Design: Livers from adult wildtype, Fah or Fah, p21 knockout mice were analyzed either after continuous treatment (ON) with NTBC or after NTBC withdrawal for 14 days (OFF).
Project description:Fumarylacetoacetate hydrolase (Fah), the last enzyme of the tyrosine degradation pathway, is specifically expressed in hepatocytes in the liver. Loss of Fah leads to liver failure in mice within 6-8 weeks. This can be prevented by blocking tyrosine degradation upstream of Fah with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC). Here, we investigate the impact of p21 on global gene expression in Fah deficiency. Keywords: treatment, genotype
Project description:FAH knockdown SNU-182 cells and corresponding controls were used for metabolic flux analysis. Parallel [U-¹³C₆]-glucose metabolic flux was conducted
Project description:Resistance to standard-of-care therapies remains a major clinical challenge in the treatment of the most common breast cancer, the hormone receptor–positive (HR+) subtype. Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors improve outcomes in early-stage HR+ disease, yet many patients relapse. Resistance mechanisms of relapsed tumors include genetic alterations, but in many cases no genetic drivers are identified. Here, we investigated mechanisms underlying resistance to CDK4/6 inhibitors using breast cancer patient-derived models and tumors. We identified an unexpected, non-catalytic nuclear function of fumarylacetoacetate hydrolase (FAH), an enzyme in the tyrosine catabolism pathway, as a driver of resistance. FAH translocated to the nucleus upon CDK4/6 inhibition, where it interacted with cyclin-dependent kinase 9 (CDK9), and promoted resistance. Nuclear FAH was enriched in tumors from relapsed patients, and inhibition of CDK9 reversed FAH-mediated resistance. These findings establish nuclear FAH as a biomarker of resistance and revealed CDK9 as a therapeutic vulnerability in CDK4/6 inhibitor-resistant HR+ breast cancer.
Project description:Resistance to standard-of-care therapies remains a major clinical challenge in the treatment of the most common breast cancer, the hormone receptor–positive (HR+) subtype. Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors improve outcomes in early-stage HR+ disease, yet many patients relapse. Resistance mechanisms of relapsed tumors include genetic alterations, but in many cases no genetic drivers are identified. Here, we investigated mechanisms underlying resistance to CDK4/6 inhibitors using breast cancer patient-derived models and tumors. We identified an unexpected, non-catalytic nuclear function of fumarylacetoacetate hydrolase (FAH), an enzyme in the tyrosine catabolism pathway, as a driver of resistance. FAH translocated to the nucleus upon CDK4/6 inhibition, where it interacted with cyclin-dependent kinase 9 (CDK9), and promoted resistance. Nuclear FAH was enriched in tumors from relapsed patients, and inhibition of CDK9 reversed FAH-mediated resistance. These findings establish nuclear FAH as a biomarker of resistance and revealed CDK9 as a therapeutic vulnerability in CDK4/6 inhibitor-resistant HR+ breast cancer.
Project description:Reprogramming metabolism plays an important role in tumor cells for maintaining their abnormal biologic behaviors. Therefore, special factors could regulate metabolic processes and influence the overall status of tumor cells. This phenomenon was obviously found in melanoma. Fumarylacetoacetate hydrolase (fumarylacetoacetase, FAH) is an enzyme encoded by the FAH gene located on the chromosome 15q25.1 region and contains 14 exons. FAH enzyme catalyzes the hydrolysis of 4- fumarylacetoacetase into fumarate and acetoacetate. It is the last enzyme in the subpathway from L-phenylalanine and tyrosine degradation. Mutations in the FAH gene cause type I tyrosinemia, which is a hereditary error of metabolism that is characterized by increased tyrosine levels in the blood and urine of patients. In the present study, we will explore whether FAH is an essential enzyme to promote multiple metabolic processes and elucidate the functions of FAH in melanoma. Gene microarrays and bioinformatics analysis of the differentially expressed genes (DEGs) were performed using A375 cells, and we concentrated on the biologic functions of FAH. In general, our work revealed several functional mechanisms of FAH in melanoma, which indicated FAH might be a potentially therapeutic target and an independent prognostic indicator for this disease.
Project description:HBV-stably transfected HepG2 cells were subjected to both FAH overexpression and siRNA-mediated FAH knockdown, and global gene expression changes were assessed by RNA microarray analysis to identify host pathways associated with FAH-dependent antitumor and antiviral effects. Comprehensive transcriptomic profiling revealed distinct FAH-regulated gene signatures linked to tumor-related biological processes and HBV regulation, providing mechanistic insights into how FAH modulates both tumor biology and antiviral responses in this in vitro system.