One of the most important metabolic hallmarks of breast cancer cells is enhanced lipogenesis. Increasing evidences suggest that fatty acid synthase (FAS) plays an important role in human breast cancer. Previously we discovered that alpha-mangostin showed apoptotic effect on human breast cancer cells via inhibiting FAS activity. The endoplasmic reticulum (ER) stress and autophagy are involved in cell apoptosis. However, the role of ER stress and autophagy in FAS inhibition induced apoptosis still remains unclear. We evaluated the effects of alpha-mangostin on ER stress and autophagy in human breast cancer cells. Intracellular FAS activity was measured by a spectrophotometer at 340 nm of NADPH absorption. Cell Counting Kit assay was used to test the cell viability. Immunoblot analysis was performed to detect protein expression levels. Apoptotic effects were detected by flow cytometry. Alpha-mangostin induced endoplasmic reticulum stress and autophagy, both of which reduced the apoptotic effect of alpha-mangostin in MDA-MB-231 cells. Palmitic acid, the end product of FAS catalyzed reaction, rescued the ER stress and autophagy induced by alpha-mangostin. Cell apoptosis was markedly promoted by inhibiting ER stress and autophagy while treating cells with alpha-mangostin. We propose a hypothesis that a combination of FAS inhibition and ER stress and autophagy inhibition has an application potential in the chemoprevention and treatment of breast cancer.

Fatty acid synthase (FAS) is a multifunctional homodimeric protein, and is the key enzyme required for the anabolic conversion of dietary carbohydrates to fatty acids. FAS synthesizes long-chain fatty acids from three substrates: acetyl-CoA as a primer, malonyl-CoA as a 2 carbon donor, and NADPH for reduction. The entire reaction is composed of numerous sequential steps, each catalyzed by a specific functional domain of the enzyme. FAS comprises seven different functional domains, among which the β-ketoacyl synthase (KS) domain carries out the key condensation reaction to elongate the length of fatty acid chain. Acyl tail length controlled fatty acid synthesis in eukaryotes is a classic example of how a chain building multienzyme works. Different hypotheses have been put forward to explain how those sub-units of FAS are orchestrated to produce fatty acids with proper molecular weight. In the present study, molecular dynamic simulation based binding free energy calculation and access tunnels analysis showed that the C16 acyl tail fatty acid, the major product of FAS, fits to the active site on KS domain better than any other substrates. These simulations supported a new hypothesis about the mechanism of fatty acid production ratio: the geometric shape of active site on KS domain might play a determinate role.

Fatty acid synthase (FAS) is highly expressed in human adipocytes and cancer cells and is considered as a dual therapeutic target for obesity and cancer treatment. Garcinone E is a natural xanthone and exists in the pericarp of Garcinia mangostana. In previous studies, xanthones were reported to be highly active inhibitors of FAS. In the present study, the detailed inhibitory mechanism of garcinone E on FAS was investigated. We found that garcinone E inhibited the activity of FAS in a concentration-dependent manner with a half-inhibitory concentration value of 3.3 μM. The inhibition kinetic results showed that the inhibition of FAS by garcinone E was competitive with respect to acetyl-CoA, mixed competitive and noncompetitive with respect to malonyl-CoA, and noncompetitive to NADPH. In addition, garcinone E showed irreversible inhibition on FAS, which was different from all other xanthones. Since FAS is believed to be a therapeutic target for obesity and cancer treatment, these findings suggest the clinical potential of garcinone E in the prevention and treatment of both obesity and cancer.

Acer truncatum Bunge is now widely cultivated throughout the world. Fatty acid synthase (FAS) is a potential target in the treatment of both obesity and cancer. Only a few FAS inhibitors have been reported. In this study, the inhibitory effect of A. truncatum seed coat (ESA) on FAS and the inhibition mechanisms were investigated using a FAS activity assay and an enzyme kinetics study. The main chemicals of ESA were analyzed with UPLC-MS/MS. The effects of ESA on 3T3-L1 adipocyte differentiation and lipid accumulation were investigated using Oil red O staining. We first identified seven main compounds (quinic acid, malic acid, gentisic acid, procyanidin dimer, procyanidin trimer, catechin, and quercetin) from 50% ethanol extracts of seed coats of A. truncatum (ESAs), which were then found to inhibit 3T3-L1 adipocyte differentiation at the concentration of 50 μg/mL. ESA obviously reduced the visible triglyceride droplets accumulation, and dramatically decreased the number of the adipocytes at a comparatively high concentration. It is suggested that the effects are due to the inhibition of FAS by ESA; FAS activity is inhibited by ESA at a half inhibition concentration (IC₅₀) of 0.57 μg/mL, which is lower than that of classically known FAS inhibitors. Meanwhile, ESA displayed different inhibition kinetics and reacting sites for FAS. These results provide new clues for the development of novel products for obesity treatment and a scientific basis for the full use of byproducts for future industrial production of vegetable oil.

Marine mangrove vegetation has been traditionally employed in folk medicine to address various ailments. Notably, Rhizophora apiculata Blume has exhibited noteworthy properties, demonstrating efficacy against cancer, viruses, and bacteria. The enzyme fatty acid synthase (FAS) plays a pivotal role in de novo fatty acid synthesis, making it a promising target for combating colon cancer. Our study focused on evaluating the FAS inhibitory effects of both the crude extract and three isolated compounds from R. apiculata. The n-butanol fraction of R. apiculata extract (BFR) demonstrated a significant inhibition of FAS, with an IC₅₀ value of 93.0 µg/mL. For inhibition via lyoniresinol-3α-O-β-rhamnopyranoside (LR), the corresponding IC₅₀ value was 20.1 µg/mL (35.5 µM). LR competitively inhibited the FAS reaction with acetyl-CoA, noncompetitively with malonyl-CoA, and in a mixed manner with NADPH. Our results also suggest that both BFR and LR reversibly bind to the KR domain of FAS, hindering the reduction of saturated acyl groups in fatty acid synthesis. Furthermore, BFR and LR displayed time-dependent inhibition for FAS, with k_obs values of 0.0045 min⁻¹ and 0.026 min⁻¹, respectively. LR also exhibited time-dependent inhibition on the KR domain, with a k_obs value of 0.019 min⁻¹. In human colon cancer cells, LR demonstrated the ability to reduce viability and inhibit intracellular FAS activity. Notably, the effects of LR on human colon cancer cells could be reversed with the end product of FAS-catalyzed chemical reactions, affirming the specificity of LR on FAS. These findings underscore the potential of BFR and LR as potent FAS inhibitors, presenting novel avenues for the treatment of human colon cancer.

Fatty acid synthase (FASN) is frequently overexpressed in human breast cancer and has emerged as a potential therapeutic target. Resveratrol has been shown to inhibit FASN activity in vitro through both fast-reversible and slow-irreversible mechanisms. In this study, resveratrol reduced intracellular fatty acid levels by inhibiting FASN activity and downregulating its expression across various breast cancer subtypes, including SK-BR-3, MCF-7, and MDA-MB-231 cells. Knockdown of FASN via small interfering RNA (siRNA) further enhanced resveratrol-induced cytotoxicity. Resveratrol significantly suppressed cell viability and triggered apoptosis, as evidenced by increased cleavage of poly(ADP-ribose) polymerase (PARP) and disruption of Bcl-2 family protein balance. Furthermore, resveratrol inhibited key signaling pathways involved in cell proliferation and survival, notably FAK, AKT, and ERK1/2. FASN silencing by siRNA also modulated the activation states of these signaling proteins. Collectively, these findings support resveratrol as a promising anti-cancer candidate that induces apoptosis in diverse breast cancer subtypes via FASN inhibition.