Selective activation of the fatty acid synthesis pathway in human prostate cancer.

A substantial subset of breast, colorectal, ovarian, endometrial and prostatic cancers displays markedly elevated expression of immunohistochemically detectable fatty acid synthase, a feature that has been associated with poor prognosis and that may be exploited in anti-neoplastic therapy. Here, using an RNA array hybridisation technique complemented by in situ hybridisation, we report that in prostate cancer fatty acid synthase expression is up-regulated at the mRNA level together with other enzymes of the same metabolic pathway. Contrary to the observations that in many cell systems (including androgen-stimulated LNCaP prostate cancer cells) fatty acid and cholesterol metabolism are co-ordinately regulated so as to supply balanced amounts of lipids for membrane biosynthesis, storage or secretion, no changes in the expression of genes involved in cholesterol synthesis were found. These findings point to selective activation of the fatty acid synthesis pathway and suggest a shift in the balance of lipogenic gene expression in a subgroup of prostate cancers.

Progestins and androgens increase expression of Spot 14 in T47-D breast tumor cells.

Enhanced expression of fatty acid synthase and other lipogenic enzymes has been observed in a subset of breast cancers with poor prognosis. This phenomenon has been related to amplification of a gene on chromosome region 11q13 encoding Spot 14, a putative regulator of lipogenic enzyme expression. In this paper we demonstrate that the induction of lipogenesis by progestins and androgens in the breast cancer cell line T47-D is accompanied by a marked increase in the expression of Spot 14. These data corroborate the correlation between Spot 14 expression and increased lipogenesis. Moreover they show that apart from gene amplification there is another steroid-regulated pathway that may enhance Spot 14 expression and lipogenesis in tumor cells.

Nandrolone decanoate does not enhance training effects but increases IGF-I mRNA in rat diaphragm.

To examine whether concomitant anabolic steroid treatment combined with training might enhance previously observed training effects (A. Bisschop, G. Gayan-Ramirez, H. Rollier, R. Gosselink, R. Dom, V. de Bock, and M. Decramer. Am. J. Respir. Crit. Care Med. 155: 1583-1589, 1997) and whether insulin-like growth factor I (IGF-I) was involved in these changes, male and female rats were submitted to inspiratory muscle training (IMT) for 8 wk (30 min/day, 5 times/wk) and were compared with untrained controls. During the last 5 wk of training, trained rats were divided to receive weekly either low-dose (LD; 1.5 mg/kg) or high-dose (HD; 7.5 mg/kg) nandrolone decanoate or saline for the IMT and control rats. In both sexes, diaphragm muscle mass and contractile properties were unchanged with treatment. In males, HD resulted in decreased diaphragm type I cross-sectional area (-15%; P < 0.05, HD vs. IMT), whereas no changes were observed in females. Finally, an increase in IGF-I mRNA levels was present in HD male (+73%; P < 0.05, HD vs. IMT) and female treated rats [LD (+58%) and HD (+96%) vs. IMT; P < 0.001]. We conclude that administration of nandrolone decanoate did not enhance the previously observed training effects in rat diaphragm, although it increased the IGF-I mRNA expression levels.

Acute treatment with corticosteroids decreases IGF-1 and IGF-2 expression in the rat diaphragm and gastrocnemius.

Massive doses of methylprednisolone (M) or triamcinolone (T) induced diaphragmatic type IIx/b atrophy, resulting in a leftward shift of the force-frequency curve in rats (). To examine the role of insulin-like growth factors (IGFs) in these changes, IGF mRNA content was measured in costal diaphragm, gastrocnemius, and liver removed from 32 rats treated daily during 5 d either with saline (control, C and pair-fed, PF), M, or T (80 mg/kg). Blood samples were taken to measure IGF-1 serum levels. RNA levels were measured by Northern and dot-blots after hybridization with rat IGF-1 or IGF-2 cDNA probes labeled with alpha-32P. Compared with C (845 +/- 128 ng/ml), IGF-1 serum levels were significantly decreased in M (699 +/- 90 ng/ml, p < 0.001 versus C) and PF animals (505 +/- 33 ng/ml, p < 0.001 versus others) and even more so, in T-treated animals (273 +/- 134 ng/ml, p < 0.001 versus others). Along the same lines, IGF-1 expression in the liver was depressed after corticosteroid treatment and in PF, whereas IGF-2 mRNA content remained unchanged. Compared with C, the relative expression of IGF-1 mRNA in the diaphragm was depressed by 44% and 69% in the M and T groups, respectively (p < 0.0001 versus C), while it was unchanged in PF animals. In the gastrocnemius, IGF-1 expression was reduced after M and T (-51% and -59%, respectively, p < 0.0001 versus C) as well as in PF animals (-40%, p < 0.001 versus C). For IGF-2, a similar pattern of expression was found in the diaphragm and the gastrocnemius. Indeed, IGF-2 mRNA tended to decrease in corticosteroid-treated rats (NS) whereas it was unchanged in PF rats. We conclude that decreased IGF expression after corticosteroid treatment was similar in diaphragm and gastrocnemius and may be responsible for the diaphragmatic changes observed after steroid treatment.

Biliary cirrhosis induces type IIx/b fiber atrophy in rat diaphragm and skeletal muscle, and decreases IGF-I mRNA in the liver but not in muscle.

BACKGROUND/AIMS: Patients with cirrhosis complain of fatigue, which in part may be due to the progressive muscle atrophy, noted especially when signs of decompensation appear. In addition, weaning from mechanical ventilation may be difficult in some patients following liver transplantation. Since little is known about the peripheral muscles and the diaphragm in cirrhosis, we investigated diaphragm and gastrocnemius histochemical properties, and diaphragm contractile properties in male rats with biliary cirrhosis. In addition, the extent to which insulin-like growth factor I (IGF-I) was involved in the regulation of muscle function was also examined, since IGF-I is known to induce growth and regeneration as well as to exert a protein anabolic action. METHODS: Ten rats underwent a sham operation, while another ten underwent bile duct ligation and excision. After 5 weeks, biliary cirrhosis was confirmed histologically in random liver biopsies. RESULTS: Compared to sham animals, diaphragm mass in cirrhotic rats was decreased by 10% (p<0.05), while masses of other respiratory (e.g. scalenus medius -21%, p<0.001) or peripheral muscles (e.g. gastrocnemius -24%, p<0.0001) decreased more. No changes in diaphragm force nor in its endurance were observed between the two groups. However, a clear decrease in the cross-sectional area of type IIx/b muscle fiber was present in both diaphragm (1360+/-147 vs 1112+/-167 microm2, p<0.02) and gastrocnemius (1954+/-265 vs 2328+/-245 microm2, p<0.02). Finally, hybridization of Northern blot with a rat cDNA IGF-I probe (gift from Dr D. Leroith, Bethesda, USA) labeled with alpha-32P revealed that in cirrhotic rats, the relative expression of IGF-I was markedly reduced by 45% in the liver (p<0.05) but was unchanged in the two muscles studied. CONCLUSIONS: In this model of biliary cirrhosis: (i) muscle wasting was less pronounced in the diaphragm than in other muscles; (ii) type IIx/b fiber atrophy in respiratory (diaphragm) and peripheral muscles (gastrocnemius) developed while diaphragm contractile properties remained unchanged; and (iii) the relative expression of IGF-I was reduced in the liver only, while it remained unchanged in the muscle. The functional significance of these changes, their pathogenesis and presence in other models and in human cirrhosis remain to be elucidated.

Effect of androgens on the germ cell-depleted testes of prenatally irradiated rats.

To study the effect of androgens on somatic testicular cells, rats were rendered germ cell depleted by prenatal irradiation (RX). Adult RX rats were treated with a desensitizing dose of a GnRH agonist (GnRHa; Zoladex), combined with an antiandrogen (Nilutamide) to preclude all androgen effects, or combined with testosterone or hCG to restore androgen action. The effect of these treatments for 3 weeks on the weight of testes and accessory sex glands, hormones (LH, FSH, testosterone, inhibin), testicular proteins, the pattern of incorporation of [35S]-methionine into testicular proteins (studied by two dimensional gel electrophoresis) and steady state mRNA levels for transferrin and androgen-binding protein (ABP) were evaluated. Combined treatment with GnRHa and antiandrogen virtually eliminated gonadotrophins, androgens and androgen effects. Testicular weight was reduced to 50% of that observed in RX controls. Treatment with GnRHa and testosterone resulted in supraphysiological levels of testosterone and testicular weights comparable to those observed in RX controls. FSH levels in these animals, however, were in the normal range. A low dose of hCG also restored testicular weight in the presence of low concentrations of serum testosterone and low normal levels of FSH. Neither polyacrylamide gel electrophoresis of total testicular proteins nor two dimensional gel electrophoresis of [35S]-methionine labelled proteins revealed striking changes in distinct testicular proteins as a result of androgen withdrawal or androgen treatment. Dot blot hybridization showed a three-fold increase in the mRNA level for ABP (expressed per microgram total RNA) in the Sertoli cell enriched testes of RX rats. This level was barely influenced by androgen withdrawal or androgen administration. The mRNA level for transferrin was increased six-fold in RX rats. A 50% reduction of this level was observed after combined treatment with GnRHa and antiandrogen. It is concluded that, in the germ cell-depleted testis, the major effect of androgens is an overall increase in protein and RNA synthesis rather than a very important and selective increase of a few gene products.