orlistat and 4-methylene-2-octyl-5-oxofuran-3-carboxylic-acid

The mechanisms that allow breast cancer (BCa) cells to metabolically sustain rapid growth are poorly understood. Here we report that BCa cells are dependent on a mechanism to supply precursors for intracellular lipid production derived from extracellular sources and that the endothelial lipase (LIPG) fulfils this function. LIPG expression allows the import of lipid precursors, thereby contributing to BCa proliferation. LIPG stands out as an essential component of the lipid metabolic adaptations that BCa cells, and not normal tissue, must undergo to support high proliferation rates. LIPG is ubiquitously and highly expressed under the control of FoxA1 or FoxA2 in all BCa subtypes. The downregulation of either LIPG or FoxA in transformed cells results in decreased proliferation and impaired synthesis of intracellular lipids.

Topics: 4-Butyrolactone; Animals; Biological Transport; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Doxycycline; Enzyme Inhibitors; Female; Gene Expression Regulation, Neoplastic; Hepatocyte Nuclear Factor 3-alpha; Hepatocyte Nuclear Factor 3-beta; Humans; Lactones; Lipase; Lipid Metabolism; MCF-7 Cells; Mice; Mice, Nude; Neoplasm Invasiveness; Orlistat; RNA, Small Interfering; Signal Transduction; Xenograft Model Antitumor Assays

Fatty acid synthase (FASN), catalyzing the de novo synthesis of fatty acids, is known to be deregulated in several cancers. Inhibition of this enzyme reduces tumor cell proliferation. Unfortunately, adverse effects and chemical instability prevent the in vivo use of the best-known inhibitors, Cerulenin and C75. Orlistat, a drug used for obesity treatment, is also considered as a potential FASN inhibitor, but its impact on glioma cell biology has not yet been described. In this study, we analyzed FASN expression in human glioma samples and primary glioblastoma cell cultures and the effects of FASN inhibition with Orlistat, Cerulenin and C75. Immunohistochemistry followed by densitometric analysis of 20 glioma samples revealed overexpression of FASN that correlated with the WHO tumor grade. Treatment of glioblastoma cells with these inhibitors resulted in a significant, dose-dependent reduction in tumor cell viability and fatty acid synthesis. Compared to Cerulenin and C75, Orlistat was a more potent inhibitor in cell cultures and cell lines. In LN229, cell-growth was reduced by 63.9 ± 8.7 % after 48 h and 200 µM Orlistat compared to controls; in LT68, the reduction in cell growth was 76.3 ± 23.7 %. Nuclear fragmentation assay and Western blotting analysis after targeting FASN with Orlistat demonstrated autophagy and apoptosis. Organotypic slice cultures treated with Orlistat showed reduced proliferation after Ki67 staining and increased caspase-3 cleavage. Our results suggest that FASN may be a therapeutic target in malignant gliomas and identify Orlistat as a possible anti-tumor drug in this setting.

Topics: 4-Butyrolactone; Apoptosis; Autophagy; Brain; Brain Neoplasms; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cells, Cultured; Cerulenin; Dose-Response Relationship, Drug; Fatty Acid Synthase, Type I; Fatty Acid Synthesis Inhibitors; Glioblastoma; Glioma; Humans; Lactones; Neoplasm Grading; Orlistat; Tissue Culture Techniques

Inhibition of FASN has emerged as a promising therapeutic target in cancer, and numerous inhibitors have been investigated. However, severe pharmacological limitations have challenged their clinical testing. The synthetic FASN inhibitor triclosan, which was initially developed as a topical antibacterial agent, is merely affected by these pharmacological limitations. Yet, little is known about its mechanism in inhibiting the growth of cancer cells. Here we compared the cellular and molecular effects of triclosan in a panel of eight malignant and non-malignant prostate cell lines to the well-known FASN inhibitors C75 and orlistat, which target different partial catalytic activities of FASN. Triclosan displayed a superior cytotoxic profile with a several-fold lower IC50 than C75 or orlistat. Structure-function analysis revealed that alcohol functionality of the parent phenol is critical for inhibitory action. Rescue experiments confirmed that end product starvation was a major cause of cytotoxicity. Importantly, triclosan, C75 and orlistat induced distinct changes to morphology, cell cycle, lipid content and the expression of key enzymes of lipid metabolism, demonstrating that inhibition of different partial catalytic activities of FASN activates different metabolic pathways. These finding combined with its well-documented pharmacological safety profile make triclosan a promising drug candidate for the treatment of prostate cancer.

Topics: 3T3 Cells; 4-Butyrolactone; Animals; Anti-Infective Agents, Local; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Drug Repositioning; Fatty Acid Synthase, Type I; Fatty Acid Synthesis Inhibitors; G1 Phase Cell Cycle Checkpoints; Humans; Lactones; Lipid Metabolism; Male; Mice; Orlistat; Prostatic Neoplasms; Structure-Activity Relationship; Triclosan