Fatty acid synthase (FAS) expression in human breast cancer cell culture supernatants and in breast cancer patients
ABSTRACT Fatty acid synthase (FAS) is selectively expressed in certain human cancers, including carcinoma of the breast, prostate, colon, ovary, and endometrium, compared to normal human tissues and therefore is a putative tumor marker. In this study, we found FAS concentrations were elevated in cell culture supernatants during cell growth in two human breast cancer cell lines but not other cancer cell lines. A quantitative enzyme-linked immunosorbent assay and Western blot analysis were employed in this study. In addition, serum FAS levels were significantly higher in breast cancer patients with different clinical stages (Stage II: 0.59+/-0.09 units/l, Stage III: 0.79+/-0.13 units/l, and Stage IV: 1.39+/-0.35 units/l) compared with healthy subjects (0.27+/-0.02 units/l, P<0.05). Taken together, our data suggest that FAS expression may be a useful tumor marker for breast cancer and play a role in assessing cancer virulence.
- SourceAvailable from: Helga Ogmundsdottir
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- "In 1994 Kuhajda and colleagues reported that a protein (oncogenic antigen-519) linked to poor prognosis in breast cancer was identical to FASN (Kuhajda et al. 1994). Since then FASN has been shown to be up-regulated in a variety of cancers such as breast (Vazquez- Martin et al. 2008; Wang et al. 2001), prostate (Migita et al. 2009) and colon (Notarnicola et al. 2012). The mechanism behind the FASN overexpression is not completely understood but sex steroid hormones and their receptor (Chalbos et al. 1987; Menendez et al. 2005b) as well as the human epidermal growth factor receptor 2 (HER2) (Kumar-Sinha et al. 2003; Vazquez-Martin et al. 2009) have been shown to have an important role involving the mitogen activated protein (MAP) kinase and phosphatidylinositol (PI) 3-kinase signalling cascades (Yang et al. 2002). "
ABSTRACT: Background The lichen compound (+)-protolichesterinic acid (+)-PA, isolated from Iceland moss, has anti-proliferative effects on several cancer cell lines. The chemical structure of (+)-PA is similar to a known fatty acid synthase (FASN) inhibitor C75. Aims To test whether the anti-proliferative activity of (+)-PA is associated with effects on FASN and HER2 (human epidermal growth factor receptor 2) and major signalling pathways. Synergism between (+)-PA and lapatinib, a HER2 active drug, was also evaluated. Materials and methods Pure compound was isolated by preparative high-performance liquid chromatography (HPLC) and purity of (+)-PA analyzed by analytical HPLC. Cell viability was assessed using Crystal violet staining. FASN and HER2 expression was estimated by immunofluorescence. The Meso Scale Discovery (MSD)® assay was used to measure activation of ERK1/2 and AKT. Synergism was estimated by the CalcuSyn software. Results Treatment with (+)-PA increased FASN expression in SK-BR-3 cells, which overexpress FASN and HER2, implying a compensatory response to inhibition of FASN activity. HER2 expression was decreased suggesting secondary downregulation. ERK1/2 and AKT signalling pathways were inhibited, probably due to reduced levels of HER2. No effects were observed in T-47D cells. Synergism between (+)-PA and lapatinib was observed in the SK-BR-3 cells. Conclusion Results suggest that the primary effect of (+)-PA is inhibition of FASN activity. Synergistic effects with lapatinib were seen only in SK-BR-3 cells, and not T-47D cells, further supporting the notion that (+)-PA acts by inhibiting FASN with secondary effects on HER2 expression and signalling. (+)-PA could therefore be a suitable agent for further testing, alone or in combination treatment against HER2-overexpressing breast cancer.Phytomedicine 10/2014; 21(12):1717–1724. DOI:10.1016/j.phymed.2014.08.006 · 2.88 Impact Factor
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ABSTRACT: A new model ELISA, based on two monoclonal antibodies, was developed for the quantification of fatty acid synthase (FAS). In this sandwich assay, a monoclonal antibody M6 was used as a capture on Nunc MaxiSorp ELISA/EIA Modules and another monoclonal antibody M3, labeled with biotin, was used as a detection antibody. More than 10 molecules of biotin were labeled on the anti-FAS monoclonal antibody using modified biotinylation conditions. The within- and between-run CVs were less than 10%, and the detection limit was 3.22 ng/mL. Recoveries were 98.54-121.95%, averaging 106.05%. The average FAS concentration obtained from the total 55 healthy volunteers blood was 4.07 +/- 1.81 ng/mL, 4.25 +/- 2.14 ng/mL in women (n = 37) and 3.70 +/- 0.74 ng/mL in men (n = 18). When compared with the previously developed polyclonal-monoclonal ELISA, a different pattern of FAS levels was observed in the supernatant of two cultured breast cancer cell lines in a time course study and there was no linear correlation between the two assays using 215 human blood samples. Thus, this new model FAS-ELISA could be used as an independent assay in measuring clinical samples. In summary, this monoclonal-monoclonal FAS-ELISA is sensitive, accurate, and precise in quantification of fatty acid synthase and has potential as a complementary tool in testing clinical samples.Journal of Immunoassay and Immunochemistry 02/2002; 23(3):279-92. DOI:10.1081/IAS-120013027 · 0.73 Impact Factor
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ABSTRACT: Activation of fatty acid synthase (FAS) expression and fatty acid synthesis is a common event in tumor cells from a variety of human cancers and is closely linked to malignant transformation and to tumor virulence in population studies of human cancer. We now show that, in contrast to nutritional regulation of lipogenesis in liver or adipose tissue, changes in fatty acid metabolism during in vitro transformation of the human mammary epithelial cell line MCF-10a are driven by increases in epidermal growth factor signaling, acting in major part through the mitogen-activated protein (MAP) kinase and phosphatidylinositol (PI) 3-kinase signaling cascades. H-ras transformation of MCF-10a cells resulted in upregulation of MAP kinase and PI 3-kinase signals, upregulation of sterol regulatory element binding protein 1 (SREBP-1) transcription factor levels, and upregulation of FAS expression and FA synthesis. Deletion of the major SREBP binding site from the FAS promoter abrogated transcription in transformed MCF-10a cells. Inhibitors of MAP and PI 3-kinases downregulated SREBP-1 levels and decreased transcription from the FAS promoter, reducing FAS expression and fatty acid synthesis in transformed MCF-10a cells and in MCF-7 and HCT116 carcinoma cells. H-ras transformation sensitized MCF-10a cells to the FAS inhibitors cerulenin and C-75. These results confirm an important role for SREBP-1 in neoplastic lipogenesis, and provide a likely basis for the linkage of upregulated fatty acid metabolism with neoplastic transformation and with tumor virulence, since MAP and PI 3-kinase signaling contributes to both.Experimental Cell Research 10/2002; 279(1):80-90. · 3.37 Impact Factor