Ornithine decarboxylase activity in mouse tumour tissue in response to refeeding and diet components

The role of diet components, gastrointestinal factors, and muscle innervation on activation of protein synthesis in skeletal muscles following oral refeeding

The aim of this study was to quantify the effect of oral refeeding on the synthesis of soluble and contractile proteins in skeletal muscles, and to evaluate to what extent diet components (carbohydrate, fat, amino acids), hormones (insulin, IGF-I, GIP), Ca2+ flux, polyamine synthesis, cyclooxygenase activity, and muscle innervation are related to activation of protein synthesis at the translational level following oral refeeding. Adult, weight-stable, non-growing mice (C57B1) were used in starvation/refeeding experiments with oral chow. Growing rats (150 g) were used in parenteral refeeding experiments. Protein synthesis was measured in vivo in mixed muscles (phenylalanine flooding), in phasic EDL muscles (in vitro), and in cultured L-6 muscle cells. Overnight starvation reduced synthesis of soluble proteins by 37 +/- 8% (from 0.242 +/- 0.025 to 0.151 +/- 0.009 microgram-1.mg-1) and contractile proteins by 55 +/- 6% (from 0.148 +/- 0.018 to 0.068 microgram-1.mg-1) (P < 0.01). Soluble proteins with a basic net charge were more sensitive to nutrition compared to neutral and acidic proteins. Somatostatin treatment before refeeding attenuated muscle protein synthesis by 15% (P < 0.02). Mechanical stimulation of the gastrointestinal tract (bulk feeding) did not activate protein synthesis in muscles, while i.v. or i.p. provision of nutrients did. Oral refeeding normalized rates of protein synthesis within 3 h (P < 0.01), independently of intact muscle innervation, Ca2+ flux, polyamine synthesis, and cyclooxygenase activity in the skeletal muscles, while it was dependent on a complete substrate composition of the oral diet. Our results support the hypothesis that amino acids, probably in concerted action with locally produced tissue IGF-I, stimulate protein synthesis in skeletal muscles during refeeding.

Tumour purine nucleotides and cell proliferation in response to exercise in rats

Voluntary physical exercise can delay the onset of anorexia and cachexia in tumour-bearing rats. A substrate deviation in the host which has been hypothesised as tumour burden is reduced despite an increase in food intake. Therefore, we determined the levels of purine nucleotides, the energy charge and the cell division rate in tumours from exercising animals in the postexercise period. Tumour content of purine nucleotides was analysed by HPLC. Tumour cell kinetics was studied by flow cytometry after incorporation of bromodeoxyuridine (BrdU) into DNA. Exercising animals demonstrated a 34.4% reduction in tumour volume (P < 0.05) but a 1.31-fold increase in energy charge in tumour tissue (P < 0.05). Labelling index (LI), DNA synthesis time (Ts) and potential doubling time (Tpot) were not significantly altered. These results suggest that the influence on tumour growth is closely related to the exercise period.

Effects of nandrolone propionate on experimental tumor growth and cancer cachexia

We studied the tumor host response to excessive doses of an anabolic steroid (nandrolone propionate, 2.5 mg 20 g intraperitoneally every second day for 11 days) with respect to body composition and tumor cell kinetics in MCG 101 sarcoma-bearing mice (C57BL/6J) with progressive cachexia. Although survival and food intake were not affected, a significant weight gain was observed that was essentially attributed to water retention. Net protein content was increased only to a minor extent (15%), of which only the liver accounted for a significant part of the body compartments. Hepatic protein accumulation was obviously caused by decreased protein degradation, since hepatic RNA content was unchanged. After anabolic steroid administration, reduced histochemical staining of succinate dehydrogenase was observed in skeletal muscles rich in oxidative type 1 fibers, but it was not different from that of tumor-bearing control animals, which was also confirmed by measurements of citrate synthase and cytochrome c oxidase activities in skeletal muscle and liver tissue. The anabolic steroid had no significant effect on tumor growth in terms of weight progression, energy state, polyamine synthesis rate, cell division rate, and cell cycle cytocompartments. We conclude that anabolic steroid supplementation is not therapeutically beneficial in counteracting progressive weight loss in experimental cancer.

Energetics of nutrition and polyamine-related tumor growth alterations in experimental cancer

The aim of this study was to evaluate whether food intake modulates experimental tumour growth by acute alterations in the energy state and blood flow of the tumour, and if so whether such changes are related to alterations in the enzyme ornithinedecarboxylase (ODC) and DNA synthesis. Inbred mice (C57BL/J) bearing a syngeneic undifferentiated and rapidly growing tumour were used. The tumour levels of high energy phosphates were measured in vivo by 31-P-NMR spectroscopy and biochemically following tissue extraction. DNA synthesis was estimated by measuring the incorporation of bromodeoxy-uridine into tumour DNA. Difluoro-methylornithine (DFMO) was used to inhibit ODC-activity. Tumour blood flow was estimated by a 132Xe local clearance technique. Tumour progression was associated with a significant decrease in tumour tissue high energy phosphates. Acute starvation decreased DNA-synthesis and tumour energy charge as well as its PCr/Pi which were rapidly normalised during subsequent refeeding. These changes were related to similar alterations in tumour blood flow. The inorganic phosphate (Pi) resonance and the resonances in the phosphomonoester (PME) region were considerably increased in tumour tissue. Inhibition of ODC-activity by DFMO decreased DNA-synthesis, which was associated with a secondary increase in tumour high energy phosphates probably due to a lowered energy demand for tumour cell division. The results demonstrate that host undernutrition was translated into retarded tumour growth associated with a decrease in the energy state and blood flow of the tumour. The results have bearing for the evaluation and planning of all treatment protocols with potential influence on food intake in experimental tumour-bearing animals.

Evaluation of mechanisms behind elevated energy expenditure in cancer patients with solid tumours

The aim of this study was to demonstrate significant factors behind elevated resting energy expenditure in weight-losing cancer patients. Therefore, weight-losing cancer patients (n = 60), with normal liver and kidney function tests, were randomized to receive one of four drug treatments for 5 days: (a) Propranolol 80 mg x 2 (beta-adrenoceptor blockade); (b) Indomethacin 50 mg x 2 (prostaglandin synthesis inhibition); (c) Morphine 5 mg x 3 (pain relief) or (d) Placebo x 2. A reference group of healthy well-nourished individuals were examined outside the formal randomization protocol and they received Propranolol 80 mg x 2. The cancer patients were randomized by a computer based algorithm stratifying for measured resting energy expenditure (REE), body composition, biochemical tests, previous therapy, tumour type and tumour stage. Resting energy expenditure was measured by indirect calorimetry in the morning after an overnight fast before and after drug treatment. beta-blockade reduced REE significantly in cancer patients from 1416 +/- 95 kcal day-1 to 1160 +/- 63 kcal day-1 (P < 0.02) and from 1472 +/- 69 vs, 1398 +/- 63 kcal day-1 (P < 0.01) in the well-nourished reference individuals. The reduction found in cancer patients (10%) was significantly larger than that in the group of reference patients (5%), (P < 0.01). Indomethacin, morphine or placebo did not induce any significant alteration in energy expenditure in our cancer patients. Propranolol treatment was associated with a significant reduction in plasma concentrations of free fatty acids (FFA), but not in plasma glycerol.(ABSTRACT TRUNCATED AT 250 WORDS)