Synthesis and antitumor activity of an inhibitor of fatty acid synthase

Abstract

Compared to normal human tissues, many common human cancers, including carcinoma of the colon, prostate, ovary, breast, and endometrium, express high levels of fatty acid synthase (FAS, EC ), the primary enzyme responsible for the synthesis of fatty acids. This differential expression of FAS between normal tissues and cancer has led to the notion that FAS is a target for anticancer drug development. Recent studies with C75, an inhibitor of fatty acid synthesis, have shown significant antitumor activity with concomitant inhibition of fatty acid synthesis in tumor tissue and normal liver. Importantly, histopathological analysis of normal tissues after C75 treatment showed no adverse effects on proliferating cellular compartments, such as bone marrow, gastrointestinal tract, skin, or lymphoid tissues. In this study, we describe the de novo synthesis of C75 based on the known mechanism of action of cerulenin and the theoretical reaction intermediates of the beta-ketoacyl synthase moiety of FAS. In addition, we demonstrate that C75 is a synthetic, chemically stable inhibitor of FAS. C75 inhibits purified mammalian FAS with characteristics of a slow-binding inhibitor and also inhibits fatty acid synthesis in human cancer cells. Treatment of human breast cancer cells with [5-(3)H]C75 demonstrates that C75 reacts preferentially with FAS in whole cells. Therefore, we have shown that the primary mechanism of the antitumor activity of C75 is likely mediated through its interaction with, and inhibition of, FAS. This development will enable the in vivo study of FAS inhibition in human cancer and other metabolic diseases.

Inhibition of fatty acid synthase (FAS) suppressesHER2/neu(erbB-2) oncogene overexpression in cancer cells

“…Given that the specificity of pharmacological inhibitors in general, cannot be conclusively determined, it is possible that chemical FAS blockers modulate HER2 localization through a FAS-independent mechanism. However, the fact that an analogous nuclear accumulation of p185 HER2 takes place after treatment with two different FAS blockers operating through different mechanisms of action (20)(21)(22) argues against a nonspecific pleiotropic effect. Therefore, it is tempting to suggest a previously undescribed working model connecting FAS activity and functioning of HER2 oncogene in tumor cells.…”

“…We first examined how blockade of FAS activity affected p185 HER2 expression in HER2-and FAS-overexpressing SK-Br3 cells. We used two well characterized chemical inhibitors of FAS activity: the natural mycotoxin cerulenin (20,21), or a more stable synthetic FAS inhibitor, the ␣-methylene-␥-butyrolactone C75 (22). A dose-dependent decrease in the expression and tyrosine phosphorylation of p185 HER2 was observed in SK-Br3 cells after 48 h of treatment with cerulenin as assessed by Western blotting.…”

The mitochondrial H+-ATP synthase and the lipogenic switch

“…Recent studies have provided strong evidence that cancer cells are identical to their undifferentiated ancestors or embryonic stem cells, not only in terms of their metabolism, but also inhibit lipid droplet formation in several experimental systems, 60,61 slightly reduced the size of iPS colonies but largely failed to affect the levels of LipidTOX-positive intracellular bodies (data not shown). The pharmacological suppression of the lipogenic activity of FASN using a synthetic, chemically stable inhibitor of FASN that inactivates the β-ketoacyl synthase (3-oxoacyl synthase), enoyl reductase and thioesterase partial activities of FASN, [62][63][64][65][66] similarly failed to significantly alter the accumulation of LipidTOX-positive intracellular bodies in iPS cells (data not shown). To address the functional effects of a deficit in de novo fatty acid biogenesis on the generation of iPS cells, we performed experiments using the three-factor (Oct4, Sox2 and Klf4) induction protocol in early-passage MEFs in the absence or presence of ACACA-and FASN-directed blockers.…”

Inhibition of tumor-associated fatty acid synthase activity antagonizes estradiol- and tamoxifen-induced agonist transactivation of estrogen receptor (ER) in human endometrial adenocarcinoma cells

“…To further establish the ability to pharmacologically inhibit FAS activity, and to provide additional evidence that FAS-dependent endogenous lipogenesis is the major mechanism modulating ER signaling in endometrial adenocarcinoma cells, a second FAS inhibitor C75 was used. The a-methylene-g-butyrolactone C75 is a synthetic, chemically stable inhibitor of FAS activity that has recently become available (Kuhajda et al, 2000b). Structurally, C75 lacks the reactive epoxide present on cerulenin, enhancing chemical stability and specificity.…”