Our previous reports demonstrated that NAC1, a BTB/POZ domain-containing nuclear protein, upregulates in recurrent ovarian serous carcinoma and participates in developing drug resistance in cancer cells. The current study applies quantitative proteomics to identify the proteins controlled by NAC1 by comparing the proteomes of SKOV3 cells with and without expression of a dominant negative NAC1 construct, N130. From the proteins that are downregulated by N130 (upregulated by NAC1), we chose to further characterize fatty acid synthase (FASN). Similar to change in protein level, the FASN transcript level in SKOV3 cells was significantly reduced by N130 induction or by NAC1 knockdown. Immunohistochemistry showed that NAC1 and FASN immunointensities in ovarian serous carcinoma tissues had a highly significant correlation (P < .0001). Moreover, we found that recurrent serous carcinomas exhibited higher FASN immunointensities than their matched primary tumors (P < .001). Multivariate analysis showed that an FASN staining score of >1 in serous carcinomas was associated with a worse overall survival time (P < .01). Finally, C93, a new FASN inhibitor, induced massive apoptosis in carboplatin/paclitaxel resistant ovarian cancer cells. In conclusion, we show that NAC1 is essential for FASN expression in ovarian serous carcinomas and the expression of FASN significantly correlates with tumor recurrence and disease aggressiveness. The dependence of drug resistant tumor cells on FASN suggests a potential application of FASN-based therapeutics for recurrent ovarian cancer patients.

The accumulation of triglycerides in the myocardium of nonketotic and overtly ketotic diabetic rats was studied. There was no increase in heart triglycerides of nonketotic rats taken off insulin treatment, although the rats exhibited several indices of diabetes. In nonketotic diabetic rats untreated with insulin, myocardial triglycerides repeatedly increased and declined to control levels. In severely ketotic rats, heart triglycerides increased about threefold and did not decline with time. In order to understand the mechanism of increase in myocardial triglycerides in ketotic diabetes, the biosynthesis of triglycerides was studied with heart homogenates. The total esterification of sn-glycero-3-phosphate was unaltered, but the synthesis of diglycerides and triglycerides was increased in the myocardium of the ketotic rat. On treatment of the diabetic rats with insulin, the synthesis of di- and triglycerides in heart homogenates reverted to control values. Thus the results of the present study demonstrate that (1) a persistent increase in myocardial triglyceride content was observed only in the ketotic diabetic rat and (2) increased synthesis of triglycerides is a factor in its accumulation in the myocardium of the ketotic rat.

The relationship between the severity of diabetes and the hepatic accumulation of triglycerides in the streptozotocin-diabetic rat was studied. A consistent increase in hepatic triglyceride content was observed only in the ketotic diabetic state. Insulin treatment of the ketotic diabetic rat resulted in the reversal of increased plasma concentrations of glucose, free fatty acids, /3-hydroxybutyric acid, and triglycerides to those observed in nondiabetic controls. Insulin treatment of the ketotic rats, however, did not completely eliminate the accumulation of the hepatic triglycerides.To determine whether increased triglyceride synthesis was a contributory factor to the hepatic triglyceride accumulation, triglyceride synthesis was studied in vitro using nuclear-free homogenates of liver. Triglyceride synthesis increased in ketotic diabetes. Insulin treatment of the ketotic rats partially reversed the increased diglyceride synthesis observed in ketosis but had no effect on the accelerated triglyceride synthesis. The effects of ketotic diabetes and insulin treatment of the diabetic rat on the activities of two key enzymes of the triglyceride biosynthetic pathway were examined next. The maximal velocities (V max ) of liver-soluble phosphatidate phosphohydrolase and of microsomal diglyceride acyltransferase increased in ketosis. Insulin treatment of the diabetic rats reverted the activity of these two enzymes to control values.The results of our study demonstrate that hepatic triglyceride synthesis in ketotic rats accelerates at a time when hepatic triglyceride content increases, the increased synthesis of triglycerides was associated with increases in the activities of two key enzymes of triglyceride biosynthesis. There was a correlation between hepatic triglyceride content and triglyceride synthesis in control, ketotic diabetic, and insulin-treated rats. These observations suggest a physiologic role for the observed changes in the accumulation of hepatic triglycerides in ketotic diabetes. DIABETES 28:472-478, May 1979.H epatic triglycerides are known to accumulate in experimental diabetes. 1 " 3 The accumulation may result from increased synthesis of triglyceride (TG) or its decreased output from liver [as very low density lipoproteins (VLDL)] or a combination of these factors. VLDL released from liver is considered to be one measure of TG synthesis in liver, since the total output of TG by the liver is proportional to the uptake and esterification of free fatty acids (FFA). 4 -5 Hepatic TG are complexed with the appropriate apoproteins and phospholipids before released as VLDL. 6 Reports on TG synthesis, measured as release of VLDL, in liver of diabetic animals are variable. Heimberg and colleagues 4 -7 -8 observed decreased secretion of TG in perfused livers of alloxan-diabetic rats. In the pancreatectomized dog with chronic diabetes, Basso and Havel 9 noted that the secretion of VLDL-TG was depressed in response to an infusion of palmitate. Balasse, Bier, and Havel, 10 however, observed increased synthesis and re...

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