Cancer during pregnancy alters the activity of rat placenta and enhances the expression of cleaved PARP, cytochrome-c and caspase 3

BACKGROUND: The presence of cancer makes it difficult to predict the progress of pregnancy and can be deleterious to the maternal-foetal relationship. Apoptosis may affect a range of placental functions and result in the retardation of foetal growth. In this work, we investigated the placental alterations produced by tumour growth and the effects on the expression of apoptotic factors in placental tissue. METHODS: Adult female Wistar rats (90 days old, n = 54) were allocated to control (C), tumour-bearing (W), or ascitic fluid-injected (A) groups and were killed on the 16(th), 19(th )or 21(st )day of pregnancy. Placental tissues were analysed using biochemical and histochemical assays. RESULTS: The placental protein content and glutathione-S-transferase activity were decreased in groups W and A. Histochemical analysis showed an increase in the number of cells with cleaved PARP, caspase 3 and cytochrome-c in groups W and A, indicating that the tumour growth clearly damaged placental tissue and affected the levels of apoptotic factors. These results were confirmed by western blotting. CONCLUSION: Since trophoblastic cells are responsible for maintaining a normal placental function, the uncontrolled death of these cells in response to tumour cell growth or substances derived from ascitic fluid could have a negative impact on foetal development. Further knowledge of these events may help to preserve the foetus and placenta during development

Dietary leucine supplementation minimises tumour-induced damage in placental tissues of pregnant, tumour-bearing rats

Background: The occurrence of cancer during pregnancy merges two complex, poorly understood metabolic and hormonal conditions. This association can exacerbate the conditions of both the mother and the foetus. The branched-chain amino acid leucine enhances cellular activity, particularly by increasing protein synthesis. This study aimed to analyse the modulatory effect of a leucine-rich diet on direct and indirect tumour-induced placental damage. This was accomplished by evaluating the expression of genes involved in protein synthesis and degradation and assessing anti-oxidant enzyme activity in placental tissues collected from pregnant, tumour-bearing rats. Results: Pregnant rats were either implanted with Walker 256 tumour cells or injected with ascitic fluid (to study the indirect effects of tumour growth) and then fed a leucine-rich diet. Animals in a control group underwent the same procedures but were fed a normal diet. On the 20th day of pregnancy, tumour growth was observed. Dams fed a normoprotein diet showed the greatest tumour growth. Injection with ascitic fluid mimicked the effects of tumour growth. Decreased placental protein synthesis and increased protein degradation were observed in both the tumour-bearing and the ascitic fluid-injected groups that were fed a normoprotein diet. These effects resulted in low placental DNA and protein content and high lipid peroxidation (measured by malondialdehyde content). Decreased placental protein synthesis-related gene expression was observed in the tumour group concomitant with increased expression of genes encoding protein degradation-associated proteins and proteolytic subunits. Conclusions: Consumption of a leucine-rich diet counteracted the effects produced by tumour growth and injection with ascitic fluid. The diet enhanced cell signalling, ameliorated deficiencies in DNA and protein content, and balanced protein synthesis and degradation processes in the placenta. The improvements in cell signalling included changes in the mTOR/eIF pathway. In conclusion, consumption of a leucine-rich diet improved placental metabolism and cell signalling in tumour-bearing rats, and these changes reduced the deleterious effects caused by tumour growth16CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP302863/2013-32010/00209-9; 2011/08276-0; 2013/16115-

Prehydrolyzed dietary protein reduces gastrocnemial DNA without impairing physical capacity in the rat

Previous studies have shown that hydrolyzed proteins exhibit antioxidant properties and may confer physical and physiological advantages when consumed by the exercising rat. The purpose of this study was to compare the effects of feeding either intact (I) and partly hydrolyzed (H) milk whey proteins on gastrocnemial DNA contents and protein metabolism in exercising Wistar rats. Protein synthesis and degradation, protein and DNA contents, and concentration of the serum insulin-like growth factor-1 (IGF1) were determined in six experimental groups according to the type of protein consumed [casein (C), whey protein isolate (I), hydrolyzed whey protein (H) and level of physical activity (sedentary (S) and trained (T)]. H produced significantly lower rates of protein synthesis and degradation and DNA contents in the gastrocnemius, while no differences were observed in the total muscle protein content and serum levels of IGF1. These results indicate that consumption of prehydrolyzed whey protein alters muscle metabolism resulting in less DNA, but maintains the muscle protein levels constant and sustain or improves physical performance, compared to the unhydrolyzed protein.Keywords: Dietary protein, hydrolyzed whey protein, peptides in muscle metabolism, phenylalanine, tyrosine, physical activityAfrican Journal of Biotechnology Vol. 12(16), pp. 2058-206

Leucine and Its Importance for Cell Signalling Pathways in Cancer Cachexia-Induced Muscle Wasting

The anabolic effects of a supplemented diet with branched-chain amino acids, especially leucine, on skeletal muscle wasting and as a co-adjuvant in cancer treatment have been well-studied. Leucine is a precursor of protein synthesis and acts as a nutritional signal, affecting multiple metabolic processes (e.g., satiety, thermogenesis, energy efficiency, and body composition). Previous studies related to nutritional therapy have mainly focused on myopenia, which is the loss of skeletal muscle mass in some pathologies, including cancer. Leucine plays a role in the maintenance and even increase of lean body mass in healthy individuals as well as the prevention of disease states that culminate in myopenia. Herein, we review the available data addressing the mechanisms by which leucine acts as a cellular signal, thereby stimulating muscle protein synthesis, leading to the inhibition of muscle catabolism, especially in an experimental model of cancer cachexia. We also show differences found in the metabolomic and proteomic analyses, including the use of leucine in maternal diets as a preventative for muscle wasting as supported by our experimental data

Leucine-rich diet induces a shift in tumour metabolism from glycolytic towards oxidative phosphorylation, reducing glucose consumption and metastasis in Walker-256 tumour-bearing rats

Leucine can stimulate protein synthesis in skeletal muscle, and recent studies have shown an increase in leucine-related mitochondria! biogenesis and oxidative phosphorylation capacity in muscle cells. However, leucine-related effects in tumour tissues are still poorly understood. Thus, we described the effects of leucine in both in vivo and in vitro models of a Walker-256 tumour. Tumour-bearing Wistar rats were randomly distributed into a control group (W; normoprotein diet) and leucine group (LW; leucine-rich diet [normoprotein +3% leucine]). After 20 days of tumour evolution, the animals underwent (18)-fludeoxyglucose positron emission computed tomography (F-18-FDG PET-CT) imaging, and after euthanasia, fresh tumour biopsy samples were taken for oxygen consumption rate measurements (Oroboros Oxygraph), electron microscopy analysis and RNA and protein extraction. Our main results from the LW group showed no tumour size change, lower tumour glucose (F-18-FDG) uptake, and reduced metastatic sites. Furthermore, leucine stimulated a shift in tumour metabolism from glycolytic towards oxidative phosphorylation, higher mRNA and protein expression of oxidative phosphorylation components, and enhanced mitochondria! density/area even though the leucine-treated tumour had a higher number of apoptotic nuclei with increased oxidative stress. In summary, a leucine-rich diet directed Walker-256 tumour metabolism to a less glycolytic phenotype profile in which these metabolic alterations were associated with a decrease in tumour aggressiveness and reduction in the number of metastatic sites in rats fed a diet supplemented with this branched-chain amino acid.9CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPSem informação302863/2013-3; 302425/2016-92012/06955-0; 2014/13334-7; 2015/21890-0; 2017/02739-

Leucine Affects The Fibroblastic Vero Cells Stimulating The Cell Proliferation And Modulating The Proteolysis Process.

Branched-chain amino acids, especially leucine, exert regulatory influences on protein and carbohydrate metabolism, ribosome biogenesis and gene expression. This study investigated the effects of leucine in fibroblastic cells analysing viability, proliferation, morphology, proteolysis enzymes activities and protein turnover. After exposure to culture medium enriched with 25 or 50 microM leucine for 24, 48 and 72 h, Vero cells have no alterations on viability and morphology. Leucine-treated cells showed increase on alkaline phosphatase activity and proliferation. The protein synthesis was slightly increased, whereas the protein degradation showed a deep reduction after leucine incubation. The chymotrypsin-like, cathepsin B and H and calpain activities were decreased in leucine-treated cells. In conclusion, the proteolytic pathways and the total protein degradation were modulated by leucine in Vero cells. Our observations support the concept that Vero cells may represent a new model for protein turnover study.38145-5

A leucine-rich diet modulates the tumor-induced down-regulation of the MAPK/ ERK and PI3K/Akt/mTOR signaling pathways and maintains the expression of the ubiquitin-proteasome pathway in the placental tissue of NMRI mice

Placental tissue injury is concomitant with tumor development. We investigated tumor-driven placental damage by tracing certain steps of the protein synthesis and degradation pathways under leucine-rich diet supplementation in MAC16 tumor-bearing mice. Cell signaling and ubiquitin-proteasome pathways were assessed in the placental tissues of pregnant mice, which were distributed into three groups on a control diet (pregnant control, tumor-bearing pregnant, and pregnant injected with MAC-ascitic fluid) and three other groups on a leucine-rich diet (pregnant, tumor-bearing pregnant, and pregnant injected with MAC-ascitic fluid). MAC tumor growth down-regulated the cell-signaling pathways of the placental tissue and decreased the levels of IRS-1, Akt/PKB, Erk/MAPK, mTOR, p70S6K, STAT3, and STAT6 phosphorylated proteins, as assessed by the multiplex Millipore Luminex assay. Leucine supplementation maintained the levels of these proteins within the established cell-signaling pathways. In the tumor-bearing group (MAC) only, the placental tissue showed increased PC5 mRNA expression, as assessed by quantitative RT-PCR, decreased 19S and 20S protein expression, as assessed by Western blot analysis, and decreased placental tyrosine levels, likely reflecting up-regulation of the ubiquitin-proteasome pathway. Similar effects were found in the pregnant injected with MAC-ascitic fluid group, confirming that the effects of the tumor were mimicked by MAC-ascitic fluid injection. Although tumor progression occurred, the degradation pathway-related protein levels were modulated under leucine-supplementation conditions. In conclusion, tumor evolution reduced the protein expression of the cell-signaling pathway associated with elevated protein degradation, thereby jeopardizing placental activity. Under the leucine-rich diet, the impact of cancer on placental function could be minimized by improving the cell-signaling activity and reducing the proteolytic process92218CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP304604/2010-0; 302863/2013-32009/11982-3; 2010/00209- 9; 2012/06955-