cerulenin and Prostatic-Neoplasms

Both experimental and epidemiological data indicate that androgens are among the main factors controlling the development, maintenance and progression of prostate cancer. Identifying the genes that are regulated by androgens represents a major step towards the elucidation of the mechanisms underlying the impact of androgens on prostate cancer cell biology and is an attractive approach to find novel targets for prostate cancer therapy. Among the genes that have been identified thus far, several genes encode lipogenic enzymes. Studies aimed at the elucidation of the mechanisms underlying androgen regulation of lipogenic genes revealed that androgens coordinately stimulate the expression of these genes through interference with the molecular mechanism controlling activation of sterol regulatory element-binding proteins (SREBPs), lipogenic transcription factors governing cellular lipid homeostasis. The resulting increase in lipogenesis serves the synthesis of key membrane components (phospholipids, cholesterol) and is a major hallmark of cancer cells. Pharmacologic inhibition of lipogenesis or RNA-interference-mediated down-regulation of key lipogenic genes induces apoptosis in cancer cell lines and reduces tumor growth in xenograft models. While increased lipogenesis is already found in the earliest stages of cancer development (PIN) and initially is androgen-responsive it persists or re-emerges with the development of androgen-independent cancer, indicating that lipogenesis is a fundamental aspect of prostate cancer cell biology and is a potential target for chemoprevention and for antineoplastic therapy in advanced prostate cancer.

Topics: Androgens; CCAAT-Enhancer-Binding Proteins; Cerulenin; Cholesterol; DNA-Binding Proteins; Fatty Acid Synthases; Gene Expression Regulation, Neoplastic; Humans; Intracellular Signaling Peptides and Proteins; Lipid Metabolism; Lipids; Male; Membrane Proteins; Prostatic Neoplasms; Signal Transduction; Sterol Regulatory Element Binding Protein 1; Sterol Regulatory Element Binding Protein 2; Transcription Factors

FAS and FACL3 are enzymes of fatty acid metabolism. In our previous studies, we found that FAS and FACL3 genes were vitamin D3-regulated and involved in the antiproliferative effect of 1alpha,25(OH)2D3 in the human prostate cancer LNCaP cells. Here, we elucidated the mechanism behind the downregulation of FAS expression by vitamin D3. Triacsin C, an inhibitor of FACL3 activity, completely abolished the downregulation of FAS expression by vitamin D3, whereas an inhibitor of FAS activity, cerulenin, had no significant effect on the upregulation of FACL3 expression by vitamin D3 in LNCaP cells. In human prostate cancer PC3 cells, in which FACL3 expression is not regulated by vitamin D3, no regulation of FAS expression was seen. This suggests that the downregulation of FAS expression by vitamin D3 is mediated by vitamin D3 upregulation of FACL3 expression. Myristic acid, one of the substrates preferential for FACL3, enhanced the repression of FAS expression by vitamin D3. The action of myristic acid was abrogated by inhibition of FACL3 activity, suggesting that the enhancement in the downregulation of FAS expression by vitamin D3 is due to the formation of myristoyl-CoA. The data suggest that vitamin D3-repression of FAS mRNA expression is the consequence of feedback inhibition of FAS expression by long chain fatty acyl-CoAs, which are formed by FACL3 during its upregulation by vitamin D3 in human prostate cancer LNCaP cells.

Topics: Cell Line, Tumor; Cerulenin; Cholecalciferol; Coenzyme A Ligases; Down-Regulation; Enzyme Inhibitors; Fatty Acid Synthases; Gene Expression Regulation, Neoplastic; Humans; Male; Myristic Acid; Prostatic Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; Time Factors; Triazenes; Up-Regulation

1alpha,25-dihydroxyvitamin D(3) (1alpha,25(OH)(2)D(3)) and its derivatives are a potential treatment of human prostate cancer. The antiproliferative action of 1alpha,25(OH)(2)D(3) is mainly exerted through nuclear vitamin D receptor (VDR)-mediated control of target gene transcription. To explore the target genes which are regulated by 1alpha,25(OH)(2)D(3) in human prostate cancer LNCaP cells, cDNA microarray was performed by using a chip that contains 3000 gene probes. The results showed that 24 genes were regulated by 1alpha,25(OH)(2)D(3). Five of them encode proteins which belong to metabolic enzymes and fatty acid biosynthesis. Fatty acid synthase (FAS) was found to be down-regulated by 1alpha,25(OH)(2)D(3), and the regulation was confirmed by real-time quantitative RT-PCR analysis. Inhibition of FAS expression by 1alpha,25(OH)(2)D(3) in LNCaP cells was more than 50% at 6h. Inhibitory effect of 1alpha,25(OH)(2)D(3) on FAS expression was completely blocked in the presence of protein synthesis inhibitor cycloheximide, indicating that the down-regulation of FAS gene expression by 1alpha,25(OH)(2)D(3) was indirect in LNCaP cells. An inhibition of FAS activity by cerulenin resulted in a strong inhibition of LNCaP cell proliferation. The inhibition of FAS expression and cell proliferation by 1alpha,25(OH)(2)D(3) seemed to be androgen-dependent, since antiandrogen, casodex and DCC-treatment of serum blocked the vitamin D action. The findings suggest that FAS is involved in the antiproliferative effect of 1alpha,25(OH)(2)D(3) in presence of androgens on prostate cancer LNCaP cells.

Topics: Androgen Antagonists; Anilides; Calcitriol; Cerulenin; Cycloheximide; Down-Regulation; Enzyme Inhibitors; Fatty Acid Synthases; Flutamide; Gene Expression Regulation, Neoplastic; Humans; Male; Nitriles; Oligonucleotide Array Sequence Analysis; Prostatic Neoplasms; Protein Synthesis Inhibitors; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tosyl Compounds; Tumor Cells, Cultured

Fatty acid synthase (FAS) is the major enzyme required to convert carbohydrates to fatty acids. Recent evidence suggests that FAS activity is essential for prostate cancer growth and survival, since blocking the enzyme activity results in cell death. In this study, the role of FAS up-regulation during prostate tumor progression in the transgenic adenocarcinoma of mouse prostate (TRAMP) model was investigated. Sensitivity to FAS anti-metabolites was also analyzed in TRAMP prostate tumor cells and tissue to determine therapeutic potential of FAS inhibition in the treatment of prostate cancer.. FAS expression was evaluated by immunohistochemistry of TRAMP tissues, including primary and metastatic lesions in mice of varying ages. FAS pathway activity was studied in vitro using TRAMP-derived cell lines and in vivo in TRAMP tissues. The sensitivity of TRAMP cell lines and tissues to the antimetabolite drugs (2R,3S)-2,3-epoxy-4-oxo-7,10-trans, transdodecadienamide (cerulenin) and C-75, which target FAS, was determined by FAS antimetabolite inhibition of 14C-acetate conversion to fatty acids, cell growth inhibition, and apoptosis analyses.. High FAS expression and activity in the TRAMP mouse prostate was evident at 12 weeks of age compared with nontransgenic littermates and further increased with age, tumor progression, and in metastatic lesions. FAS pathway inhibition resulted in a dose-dependent reduction in cell survival and decreased enzyme activity in these models.. These data suggest that the up-regulation of FAS expression play a role in tumorigenesis of the prostate in the TRAMP model and hence can provide valuable insight into human prostate cancer. Given the response of tumor cells to FAS antimetabolites, FAS may serve as a novel target for prostate cancer therapy.

Topics: Adenocarcinoma; Animals; Apoptosis; Blotting, Western; Cerulenin; Disease Models, Animal; Disease Progression; Enzyme Inhibitors; Fatty Acid Synthases; Immunohistochemistry; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Prostatic Neoplasms