Fatty Acid Synthase Inhibitors Induce Apoptosis in Non-Tumorigenic Melan-A Cells Associated with Inhibition of Mitochondrial Respiration

Author(s)

Rossato, Franco A. ^[1] ; Zecchin, Karina G. ^{[1, 2]} ; La Guardia, Paolo G. ^[1] ; Ortega, Rose M. ^[2] ; Alberici, Luciane C. ^[3] ; Costa, Rute A. P. ^[1] ; Catharino, Rodrigo R. ^[1] ; Graner, Edgard ^[2] ; Castilho, Roger F. ^[1] ; Vercesi, Anibal E. ^[1]

Affiliation

^[1] Univ Estadual Campinas UNICAMP, Fac Ciencias Med, Dept Patol Clin, Campinas, SP - Brazil

^[2] Univ Estadual Campinas UNICAMP, Fac Odontol Piracicaba, Dept Diagnost Oral, Piracicaba, SP - Brazil

^[3] Univ Sao Paulo, Fac Ciencias Farmaceut Ribeirao Preto, Dept Quim & Fis, BR-14049 Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: PLoS One; v. 9, n. 6 JUN 25 2014.
• Web of Science Citations: 17

Abstract

The metabolic enzyme fatty acid synthase (FASN) is responsible for the endogenous synthesis of palmitate, a saturated long-chain fatty acid. In contrast to most normal tissues, a variety of human cancers overexpress FASN. One such cancer is cutaneous melanoma, in which the level of FASN expression is associated with tumor invasion and poor prognosis. We previously reported that two FASN inhibitors, cerulenin and orlistat, induce apoptosis in B16-F10 mouse melanoma cells via the intrinsic apoptosis pathway. Here, we investigated the effects of these inhibitors on non-tumorigenic melan-a cells. Cerulenin-and orlistat treatments were found to induce apoptosis and decrease cell proliferation, in addition to inducing the release of mitochondrial cytochrome c and activating caspases-9 and -3. Transfection with FASN siRNA did not result in apoptosis. Mass spectrometry analysis demonstrated that treatment with the FASN inhibitors did not alter either the mitochondrial free fatty acid content or composition. This result suggests that cerulenin- and orlistat-induced apoptosis events are independent of FASN inhibition. Analysis of the energy-linked functions of melan-a mitochondria demonstrated the inhibition of respiration, followed by a significant decrease in mitochondrial membrane potential (Delta psi m) and the stimulation of superoxide anion generation. The inhibition of NADH-linked substrate oxidation was approximately 40% and 61% for cerulenin and orlistat treatments, respectively, and the inhibition of succinate oxidation was approximately 46% and 52%, respectively. In contrast, no significant inhibition occurred when respiration was supported by the complex IV substrate N,N,N',N' -tetramethyl-p-phenylenediamine (TMPD). The protection conferred by the free radical scavenger acetyl-cysteine indicates that the FASN inhibitors induced apoptosis through an oxidative stress-associated mechanism. In combination, the present results demonstrate that cerulenin and orlistat induce apoptosis in non-tumorigenic cells via mitochondrial dysfunction, independent of FASN inhibition. (AU)

• FAPESP's process: 06/59786-0 - Energetic metabolism, intracellular homeostasis of CA2+ and mitochondrial oxidative stress in cell death
• Grantee: Aníbal Eugênio Vercesi
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 11/50400-0 - Mitochondrial energy metabolism, redox state and functionality in cell death and cardiometabolic and neurodegenerative disorders
• Grantee: Aníbal Eugênio Vercesi
• Support Opportunities: Research Projects - Thematic Grants