Anastrozole Regulates Fatty Acid Synthase in Breast Cancer.
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ABSTRACT:
SUBMITTER: Cairns J
PROVIDER: S-EPMC8742770 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Fatty acid synthase (FASN), the key enzyme for endogenous synthesis of fatty acids, is overexpressed and hyperactivated in a biologically aggressive subset of sex steroid-related tumors, including breast carcinomas. Using pharmacological and genetic approaches, we assessed the molecular relationship between FASN signaling and estrogen receptor alpha (ER?) signaling in breast cancer. The small compound C75, a synthetic slow-binding inhibitor of FASN activity, induced a dramatic augmentation of estradiol (E2)-stimulated, ER?-driven transcription. FASN and ER? were both necessary for the synergistic activation of ER? transcriptional activity that occurred following co-exposure to C75 and E2: first, knockdown of FASN expression using RNAi (RNA interference) drastically lowered (>100 fold) the amount of E2 required for optimal activation of ER?-mediated transcriptional activity; second, FASN blockade synergistically increased E2-stimulated ER?-mediated transcriptional activity in ER?-negative breast cancer cells stably transfected with ER?, but not in ER?-negative parental cells. Non-genomic, E2-regulated cross-talk between the ER? and MAPK pathways participated in these phenomena. Thus, treatment with the pure antiestrogen ICI 182?780 or the potent and specific inhibitor of MEK/ERK, U0126, was sufficient to abolish the synergistic nature of the interaction between FASN blockade and E2-stimulated ER? transactivation. FASN inhibition suppressed E2-stimulated breast cancer cell proliferation and anchorage-independent colony formation while promoting the reduction of ER? protein. FASN blockade resulted in the increased expression and nuclear accumulation of the cyclin-dependent kinase inhibitors p21WAF1/CIP1 and p27Kip1, two critical mediators of the therapeutic effects of antiestrogen in breast cancer, while inactivating AKT, a key mediator of E2-promoted anchorage-independent growth. The ability of FASN to regulate E2/ER? signaling may represent a promising strategy for anticancer treatment involving a new generation of FASN inhibitors.
| S-EPMC5337623 | biostudies-literature
Project description:Fatty acid metabolism is closely associated with the occurrence and development of tumors. The aim of the present study was to investigate whether the key enzyme involved in fatty acid synthesis, fatty acid synthase (FASN), mediates fatty acid changes that affect the activity and migration of breast cancer cells, and whether specific fatty acids play a role in tumor metastasis. The difference in serum fatty acid profiles between patients with invasive ductal carcinoma (IDC) and healthy controls was evaluated by gas chromatography-mass spectrometry (GC-MS) fatty acid profile analysis, and it was revealed that five types of fatty acids may be potential tumor markers in IDC. Immunohistochemistry and GC-MS analysis revealed that FASN expression affected the serum fatty acid profiles of patients with IDC. Following FASN knockdown, the migration of SK-Br-3 breast cancer cells was inhibited, and the contents of various fatty acids both inside and outside the cell decreased, while the contents of various fatty acids inside and outside the cell increased following FASN overexpression. The results of the present study revealed that the expression level of FASN affected the content of fatty acids in IDC tissues and breast cancer cell lines, and that FASN-mediated changes in specific fatty acids promoted tumor cell migration.
| S-EPMC7681230 | biostudies-literature
Project description:The identification of clinically important molecular mechanisms driving endocrine resistance is a priority in estrogen receptor-positive (ER+) breast cancer. Although both genomic and non-genomic cross-talk between the ER and growth factor receptors such as human epidermal growth factor receptor 2 (HER2) has frequently been associated with both experimental and clinical endocrine therapy resistance, combined targeting of ER and HER2 has failed to improve overall survival in endocrine non-responsive disease. Herein, we questioned the role of fatty acid synthase (FASN), a lipogenic enzyme linked to HER2-driven breast cancer aggressiveness, in the development and maintenance of hormone-independent growth and resistance to anti-estrogens in ER/HER2-positive (ER+/HER2+) breast cancer. The stimulatory effects of estradiol on FASN gene promoter activity and protein expression were blunted by anti-estrogens in endocrine-responsive breast cancer cells. Conversely, an AKT/MAPK-related constitutive hyperactivation of FASN gene promoter activity was unaltered in response to estradiol in non-endocrine responsive ER+/HER2+ breast cancer cells, and could be further enhanced by tamoxifen. Pharmacological blockade with structurally and mechanistically unrelated FASN inhibitors fully impeded the strong stimulatory activity of tamoxifen on the soft-agar colony forming capacity-an in vitro metric of tumorigenicity-of ER+/HER2+ breast cancer cells. In vivo treatment with a FASN inhibitor completely prevented the agonistic tumor-promoting activity of tamoxifen and fully restored its estrogen antagonist properties against ER/HER2-positive xenograft tumors in mice. Functional cancer proteomic data from The Cancer Proteome Atlas (TCPA) revealed that the ER+/HER2+ subtype was the highest FASN protein expressor compared to basal-like, HER2-enriched, and ER+/HER2-negative breast cancer groups. FASN is a biological determinant of HER2-driven endocrine resistance in ER+ breast cancer. Next-generation, clinical-grade FASN inhibitors may be therapeutically relevant to countering resistance to tamoxifen in FASN-overexpressing ER+/HER2+ breast carcinomas.
| S-EPMC7961649 | biostudies-literature
Project description:Fatty acid synthase (FASN) plays an important role in cancer development, providing excess lipid sources for cancer growth by participating in de novo lipogenesis. Although several inhibitors of FASN have been developed, there are many limitations to using FASN inhibitors alone as cancer therapeutics. We therefore attempted to effectively inhibit cancer cell growth by using a FASN inhibitor in combination with an inhibitor of a deubiquitinating enzyme USP14, which is known to maintain FASN protein levels in hepatocytes. However, when FASN and USP14 were inhibited together, there were no synergistic effects on cancer cell death compared to inhibition of FASN alone. Surprisingly, USP14 rather reduced the protein levels and activity of FASN in cancer cells, although it slightly inhibited the ubiquitination of FASN. Indeed, treatment of an USP14 inhibitor IU1 did not significantly affect FASN levels in cancer cells. Furthermore, from an analysis of metabolites involved in lipid metabolism, metabolite changes in IU1-treated cells were significantly different from those in cells treated with a FASN inhibitor, Fasnall. These results suggest that FASN may not be a direct substrate of USP14 in the cancer cells. Consequently, we demonstrate that USP14 regulates proliferation of the cancer cells in a fatty acid synthase-independent manner, and targeting USP14 in combination with FASN may not be a viable method for effective cancer treatment.
| S-EPMC8707130 | biostudies-literature
Project description:The lipogenic enzyme fatty acid synthase (FAS) is up-regulated in a wide variety of cancers, and is considered a potential metabolic oncogene by virtue of its ability to enhance tumor cell survival. Inhibition of tumor FAS causes both cell cycle arrest and apoptosis, indicating FAS is a promising target for cancer treatment.Here, we used gene expression profiling to conduct a global study of the cellular processes affected by siRNA mediated knockdown of FAS in MDA-MB-435 mammary carcinoma cells. The study identified 169 up-regulated genes (> or = 1.5 fold) and 110 down-regulated genes (< or = 0.67 fold) in response to knockdown of FAS. These genes regulate several aspects of tumor function, including metabolism, cell survival/proliferation, DNA replication/transcription, and protein degradation. Quantitative pathway analysis using Gene Set Enrichment Analysis software further revealed that the most pronounced effect of FAS knockdown was down-regulation in pathways that regulate lipid metabolism, glycolysis, the TCA cycle and oxidative phosphorylation. These changes were coupled with up-regulation in genes involved in cell cycle arrest and death receptor mediated apoptotic pathways.Together these findings reveal a wide network of pathways that are influenced in response to FAS knockdown and provide new insight into the role of this enzyme in tumor cell survival and proliferation.
| S-EPMC1913522 | biostudies-literature
Project description:De novo fatty acid (FA) synthesis is required for prostate cancer (PCa) survival and progression. As a key enzyme for FA synthesis fatty acid synthase (FASN) is often overexpressed in human prostate cancers and its expression correlates with worse prognosis and poor survival. P300 is an acetyltransferase that acts as a transcription co-activator. Increasing evidence suggests that P300 is a major PCa promoter, although the underlying mechanism remains poorly understood. Here, we demonstrated that P300 binds to and increases histone H3 lysine 27 acetylation (H3K27Ac) in the FASN gene promoter. We provided evidence that P300 transcriptionally upregulates FASN expression and promotes lipid accumulation in human PCa cells in culture and Pten knockout prostate tumors in mice. Pharmacological inhibition of P300 decreased FASN expression and lipid droplet accumulation in PCa cells. Immunohistochemistry analysis revealed that expression of P300 protein positively correlates with FASN protein levels in a cohort of human PCa specimens. We further showed that FASN is a key mediator of P300-induced growth of PCa cells in culture and in mice. Together, our findings demonstrate P300 as a key factor that regulates FASN expression, lipid accumulation and cell growth in PCa. They also suggest that this regulatory pathway can serve as a new therapeutic target for PCa treatment.
| S-EPMC4924775 | biostudies-literature
Project description:T cell activation and effector function is characterized by changes in metabolism. Altered metabolism is common to almost all types of activated T cells, but fatty acid synthesis seems to especially drive the formation of Th17 cells. Indeed, research has demonstrated that inhibition of early fatty acid synthesis through targeting of acetyl-CoA carboxylase (ACC1) can inhibit Th17 cell formation and instead promote the generation of regulatory T cells. Fatty acid synthase (FASN) is downstream of ACC, and previous studies have shown that FASN activity influences both cancer and inflammation. However, it remains to be determined whether FASN is a viable target for inhibiting Th17 cell function. Here, we demonstrate that FASN is a critical metabolic control for the generation of inflammatory subsets of Th17 cells. Conversely, inhibiting FASN function promotes IFN-? production by Th1 and Th1-like Th17 cells. In vivo, inhibition of FASN, specifically in Th17 cells, leads to reduction of experimental autoimmune encephalomyelitis disease. These studies demonstrate the necessity of FASN in the autoimmune inflammatory function of Th17 cells.
| S-EPMC5636042 | biostudies-literature
Project description:Cancer cells exhibit an aberrant metabolism which facilitates more efficient production of biomass, and hence tumor growth and progression. The genetic cues modulating this metabolic switch remain largely undetermined, however. Here we identify a metabolic function for PML which reveals an unexpected role for this bona-fide tumor suppressor in pro-survival activity in breast cancer. We find that PML acts as both a negative regulator of PGC1A acetylation and as a potent activator of peroxisome proliferator-activated receptor (PPAR) signaling and fatty acid oxidation (FAO). We further show that as FAO PML promotes ATP production, inhibits anoikis, and allows luminal filling in 3D basement membrane breast culture models. Furthermore, analysis of breast cancer biopsies reveals that PML is over-expressed in a subset of breast cancers, and is enriched in triple-negative cases. Indeed, PML expression in breast cancer correlates strikingly with reduced time to recurrence, a gene signature of poor prognosis and activated PPAR signaling. These findings have important therapeutic implications, as PML and its key role in FAO metabolism are amenable to pharmacological suppression as a mode of cancer prevention and treatment. Mouse livers from Pml-WT and Pml-KO mice were harvested after 20 week diet with high fat diet (60% Cal from fat; Harlan 06414) or control diet (10% Cal from fat; Harlan 08806). Mice were fasted for 8h prior to tissue harvesting in order to avoid the effect of immediate food intake. 3 tissue extracts per genotype and condition were analyzed (out of a total of 8 mice per group).
2013-01-29 | E-GEOD-39220 | biostudies-arrayexpress
Project description:IntroductionThe human epidermal growth factor receptor 2 (HER2) is a validated therapeutic target in breast cancer. Heterodimerization of HER2 with other HER family members results in enhanced tyrosine phosphorylation and activation of signal transduction pathways. HER2 overexpression increases the translation of fatty acid synthase (FASN), and FASN overexpression markedly increases HER2 signaling, which results in enhanced cell growth. However, the molecular mechanism and regulation of HER2 and FASN interaction are not well defined. Lapatinib is a small-molecule tyrosine kinase inhibitor that blocks phosphorylation of the epidermal growth factor receptor and HER2 in breast cancer cells, resulting in apoptosis. We hypothesized that FASN is directly phosphorylated by HER2, resulting in enhanced signaling and tumor progression in breast cancer cells.MethodsUsing mass spectrometry, we identified FASN as one of the proteins that is dephosphorylated by lapatinib in SKBR3 breast cancer cells. Immunofluorescence, immunoprecipitation, Western blotting, a kinase assay, a FASN enzymatic activity assay, an invasion assay, a cell viability assay and zymography were used to determine the role of FASN phosphorylation in invasion of SKBR3 and BT474 cells. The FASN inhibitor C75 and small interfering RNA were used to downregulate FASN expression and/or activity.ResultsOur data demonstrated that FASN is phosphorylated when it is in complex with HER2. FASN phosphorylation was induced by heregulin in HER2-overexpressing SKBR3 and BT474 breast cancer cells. Heregulin-induced FASN phosphorylation resulted in increased FASN enzymatic activity, which was inhibited by lapatinib. The FASN inhibitor C75 suppressed FASN activity by directly inhibiting HER2 and FASN phosphorylation. Blocking FASN phosphorylation and activity by lapatinib or C75 suppressed the activity of matrix metallopeptidase 9 and inhibited invasion of SKBR3 and BT474 cells.ConclusionsFASN phosphorylation by HER2 plays an important role in breast cancer progression and may be a novel therapeutic target in HER2-overexpressing breast cancer cells.
| S-EPMC3046439 | biostudies-literature
Project description:NO regulates a variety of physiological processes, including cell proliferation, differentiation, and inflammation. S-nitrosylation, a NO-mediated reversible protein modification, leads to changes in the activity and function of proteins. In particular, the role of S-nitrosylation during adipogenesis is largely unknown. We hypothesized that the normal physiological levels of NO, but not the excess levels generated under severe conditions, such as inflammation, may be critically involved in the proper regulation of adipogenesis. We found that endogenous S-nitrosylation of proteins was required for adipocyte differentiation. By performing a biotin-switch assay, we identified FAS, a key lipogenic enzyme in adipocytes, as a target of S-nitrosylation during adipogenesis. Interestingly, we also observed that the dimerization of FAS increased in parallel with the amount of S-nitrosylated FAS during adipogenesis. In addition, we found that exogenous NO enhanced the dimerization and the enzymatic activity of FAS. Moreover, site-directed mutagenesis of three predicted S-nitrosylation sites indicated that S-nitrosylation of FAS at Cys(1471)and Cys(2091), but not at Cys(1127), increased its enzymatic activity. Taken together, these results suggest that the S-nitrosylation of FAS at normal physiological levels of NO increases its activity through dimerization and may contribute to the proper regulation of adipogenesis.
| S-EPMC4808769 | biostudies-literature