TY - JOUR
T1 - Fatty Acid Synthase Inhibition Triggers Apoptosis during S Phase in Human Cancer Cells
AU - Zhou, Weibo
AU - Simpson, P. Jeanette
AU - McFadden, Jill M.
AU - Townsend, Craig A.
AU - Medghalchi, Susan M.
AU - Vadlamudi, Aravinda
AU - Pinn, Michael L.
AU - Ronnett, Gabriele V.
AU - Kuhajda, Francis P.
PY - 2003/11/1
Y1 - 2003/11/1
N2 - C75, an inhibitor of fatty acid synthase (FAS), induces apoptosis in cultured human cancer cells. Its proposed mechanism of action linked high levels of malonyl-CoA after FAS inhibition to potential downstream effects including inhibition of carnitine palmitoyltransferase-1 (CPT-1) with resultant inhibition of fatty acid oxidation. Recent data has shown that C75 directly stimulates CPT-1 increasing fatty acid oxidation in MCF-7 human breast cancer cells despite inhibitory concentrations of malonyl-CoA. In light of these findings, we have studied fatty acid metabolism in MCF7 human breast cancer cells to elucidate the mechanism of action of C75. We now report that: (a) in the setting of increased fatty acid oxidation, C75 inhibits fatty acid synthesis; (b) C273, a reduced form of C75, is unable to inhibit fatty acid synthesis and is nontoxic to MCF7 cells; (c) C75 and 5-(tetradecyloxy)-2-furoic acid (TOFA), an inhibitor of acetyl-CoA carboxylase, both cause a significant reduction of fatty acid incorporation into phosphatidylcholine, the major membrane phospholipid, within 2 h; (d) pulse chase studies with [ 14C]acetate labeling of membrane lipids show that both C75 and TOFA accelerate the decay of 14C-labeled lipid from membranes within 2 h; (e) C75 also promotes a 2-3-fold increase in oxidation of membrane lipids within 2 h; and (f) because interference with phospholipid synthesis during S phase is known to trigger apoptosis in cycling cells, we performed double-labeled terminal deoxynucleotidyltransferase-mediated nick end labeling and BrdUrd analysis with both TOFA and C75. C75 triggered apoptosis during S phase, whereas TOFA did not. Moreover, application of TOFA 2 h before C75 blocked the C75 induced apoptosis, whereas etomoxir did not. Taken together these data indicate that FAS inhibition and its downstream inhibition of phospholipid production is a necessary part of the mechanism of action of C75. CPT-1 stimulation does not likely play a role in the cytotoxic response. The continued ability of TOFA to rescue cancer cells from C75 cytotoxicity implies a proapoptotic role for malonyl-CoA independent of CPT-1 that selectively targets cancer cells as they progress into S phase.
AB - C75, an inhibitor of fatty acid synthase (FAS), induces apoptosis in cultured human cancer cells. Its proposed mechanism of action linked high levels of malonyl-CoA after FAS inhibition to potential downstream effects including inhibition of carnitine palmitoyltransferase-1 (CPT-1) with resultant inhibition of fatty acid oxidation. Recent data has shown that C75 directly stimulates CPT-1 increasing fatty acid oxidation in MCF-7 human breast cancer cells despite inhibitory concentrations of malonyl-CoA. In light of these findings, we have studied fatty acid metabolism in MCF7 human breast cancer cells to elucidate the mechanism of action of C75. We now report that: (a) in the setting of increased fatty acid oxidation, C75 inhibits fatty acid synthesis; (b) C273, a reduced form of C75, is unable to inhibit fatty acid synthesis and is nontoxic to MCF7 cells; (c) C75 and 5-(tetradecyloxy)-2-furoic acid (TOFA), an inhibitor of acetyl-CoA carboxylase, both cause a significant reduction of fatty acid incorporation into phosphatidylcholine, the major membrane phospholipid, within 2 h; (d) pulse chase studies with [ 14C]acetate labeling of membrane lipids show that both C75 and TOFA accelerate the decay of 14C-labeled lipid from membranes within 2 h; (e) C75 also promotes a 2-3-fold increase in oxidation of membrane lipids within 2 h; and (f) because interference with phospholipid synthesis during S phase is known to trigger apoptosis in cycling cells, we performed double-labeled terminal deoxynucleotidyltransferase-mediated nick end labeling and BrdUrd analysis with both TOFA and C75. C75 triggered apoptosis during S phase, whereas TOFA did not. Moreover, application of TOFA 2 h before C75 blocked the C75 induced apoptosis, whereas etomoxir did not. Taken together these data indicate that FAS inhibition and its downstream inhibition of phospholipid production is a necessary part of the mechanism of action of C75. CPT-1 stimulation does not likely play a role in the cytotoxic response. The continued ability of TOFA to rescue cancer cells from C75 cytotoxicity implies a proapoptotic role for malonyl-CoA independent of CPT-1 that selectively targets cancer cells as they progress into S phase.
UR - http://www.scopus.com/inward/record.url?scp=0242694902&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0242694902&partnerID=8YFLogxK
M3 - Article
C2 - 14612531
AN - SCOPUS:0242694902
VL - 63
SP - 7330
EP - 7337
JO - Journal of Cancer Research
JF - Journal of Cancer Research
SN - 0099-7013
IS - 21
ER -