Oxidative stress and TGF-ß1 induction by metformin in MCF-7 and MDA-MB-231 human breast cancer cells are accompanied with the downregulation of genes related to cell proliferation, invasion and metastasis.

High doses of metformin induces oxidative stress (OS) and transforming growth factor ß1 (TGF-ß1) in breast cancer cells, which was associated with increased cancer stem cell population, local invasion, liver metastasis and treatment resistance. Considering the impact of TGF- ß1 and OS in breast cancer and the interrelation between these two pathways, the objective of this work was to investigate the effects of consecutive metformin treatments, at a non-cytotoxic dosage, in TGF- ß1 targets in MCF-7 and MDA-MB-231 cells. Cells were exposed to 6 µM of metformin for seven consecutive passages. Samples were collected to immunocytochemistry (evaluation of p53, Nf-кB, NRF2 and TGF-ß1), biochemical (determination of lipoperoxidation, total thiols and nitric oxide/peroxynitrite levels) and molecular biology analyzes (microarray and Real-time quantitative array PCR). Microarray analysis confirmed alterations in genes related to OS and TGF-ß1. Treatment interfered in several TGF-ß1 target-genes. Metformin upregulated genes involved in OS generation and apoptosis, and downregulated genes associated with metastasis and epithelial mesenchymal transition in MCF-7 cells. In MDA-MB-231 cells, metformin downregulated genes involved with cell invasion, viability and proliferation. The results shows that even a non-cytotoxic dosage of metformin can promote a less aggressive profile of gene expression in breast cancer cells.

Creatine supplementation in Walker-256 tumor-bearing rats prevents skeletal muscle atrophy by attenuating systemic inflammation and protein degradation signaling.

PURPOSE: The aim of this study was to investigate the effects of creatine supplementation on muscle wasting in Walker-256 tumor-bearing rats. METHODS: Wistar rats were randomly assigned into three groups (n = 10/group): control (C), tumor bearing (T), and tumor bearing supplemented with creatine (TCr). Creatine was provided in drinking water for a total of 21 days. After 11 days of supplementation, tumor cells were implanted subcutaneously into T and TCr groups. The animals' weight, food and water intake were evaluated along the experimental protocol. After 10 days of tumor implantation (21 total), animals were euthanized for inflammatory state and skeletal muscle cross-sectional area measurements. Skeletal muscle components of ubiquitin-proteasome pathways were also evaluated using real-time PCR and immunoblotting. RESULTS: The results showed that creatine supplementation protected tumor-bearing rats against body weight loss and skeletal muscle atrophy. Creatine intake promoted lower levels of plasma TNF-α and IL-6 and smaller spleen morphology changes such as reduced size of white pulp and lymphoid follicle compared to tumor-bearing rats. In addition, creatine prevented increased levels of skeletal muscle Atrogin-1 and MuRF-1, key regulators of muscle atrophy. CONCLUSION: Creatine supplementation prevents skeletal muscle atrophy by attenuating tumor-induced pro-inflammatory environment, a condition that minimizes Atrogin-1 and MuRF-1-dependent proteolysis.

Evaluation of resistance training to improve muscular strength and body composition in cancer patients undergoing neoadjuvant and adjuvant therapy: a meta-analysis.

PURPOSE: Muscle atrophy and strength decline are two of the most prominent characteristics in cancer patients undergoing cancer therapy, leading to decreased functional ability and reduced quality of life. Therefore, the aim is to systematically review research evidence of the effects of resistance exercise (RE) on lower-limb muscular strength, lean body mass (LBM), and body fat (BF) in cancer patients undertaking neoadjuvant or adjuvant therapy. METHODS: This research was conducted using the following online database: Clinical Trial Register, Cochrane Trial Register, PubMed, SPORT Discus, and SciELO, from September 2014 until May 2015. We used the following keywords in various combinations with a systematic search: "Cancer therapy," "Wasting muscle," "Muscle loss," "Muscle function," "Neoadjuvant therapy," "Adjuvant thera-py," "Resistance Training," "Weight training," and "Exercise." After selection of 272 full-text articles, 14 publications were included in this meta-analysis. RESULTS: Resistance exercise (RE) during neoadjuvant or adjuvant therapy increased lower-limb muscular strength (mean: 26.22 kg, 95% CI [16.01, 36.43], heterogeneity: P = <0.01, I 2 = 76%, P = 0.00001) when compared to controls over time. Similarly, lean body mass (LBM) increased (mean 0.8 kg, 95% CI [0.7, 0.9], heterogeneity: P = 0.99, I 2 = 0%, P < 0.00001), and decreased body fat (BF) (mean: -1.3 kg, 95% CI [-1.5, 1.1], heterogeneity: P = 0.93, I2 = 0%, P < 0.00001) compared to controls over time. CONCLUSION: RE is effective to increase lower-limb muscular strength, increase LBM, and decrease BF in cancer patients undergoing neoadjuvant and adjuvant therapy regardless of the kind of treatment. IMPLICATIONS FOR CANCER SURVIVORS: RE increases muscle strength, maintains LBM, and reduces BF in cancer patients undergoing adjuvant and neoadjuvant therapies. Cancer patients and survivors should consider undertaking RE as an effective countermeasure for treatment-related adverse effects to the musculoskeletal system.

Isoflavin-ß modifies muscle oxidative stress and prevents a thyrotoxicosis-induced loss of muscle mass in rats.

INTRODUCTION: We sought to verify whether isoflavin-beta (Iso-ß), a mixture of isoflavones with antioxidant properties, could prevent thyrotoxicosis-induced loss of muscle mass and the participation of oxidative stress (OS) in the mechanisms of this prevention. METHODS: Two experimental periods of thyrotoxicosis induction were used in Wistar rats: 3 and 5 days to assess Iso-ß effects before and after thyrotoxicosis-induced muscle wasting. After euthanasia, peritoneal fat and gastrocnemius muscle were collected, weighed, and muscle OS was assessed. RESULTS: Iso-ß prevented the loss of gastrocnemius mass in thyrotoxic rats through the prevention of muscle OS generation during thyrotoxicosis, increasing muscle total antioxidant capacity and decreasing mitochondrial cytochrome c oxidase activity, lipid peroxidation, and protein carbonyl content. CONCLUSION: Iso-ß decreased oxidative modification of proteins, which is known to exert a major role during proteolysis induction and is present in thyrotoxic myopathy, highlighting the potential action of Iso-ß in this complication of the disease. Muscle Nerve 56: 975-981, 2017.

Creatine supplementation prevents hyperhomocysteinemia, oxidative stress and cancer-induced cachexia progression in Walker-256 tumor-bearing rats.

The purpose of this study was to investigate (1) the impact of tumor growth on homocysteine (Hcy) metabolism, liver oxidative stress and cancer cachexia and, (2) the potential benefits of creatine supplementation in Walker-256 tumor-bearing rats. Three experiments were conducted. First, rats were killed on days 5 (D5), 10 (D10) and 14 (D14) after tumor implantation. In experiment 2, rats were randomly assigned to three groups designated as control (C), tumor-bearing (T) and tumor-bearing supplemented with creatine (TCr). A life span experiment was conducted as the third experiment. Creatine was supplied in drinking water for 21 days (8 g/L) in all cases. Tumor implantation consisted of a suspension of Walker-256 cells (8.0 × 10(7) cells in 0.5 mL of PBS). The progressive increase (P < 0.05) in tumor mass coincided with a progressively lower body weight and higher hepatic oxidative stress; plasma Hcy concentration was 80 % higher (P < 0.05) by 10 days of tumor implantation. Impaired Hcy metabolism was evidenced by decreased hepatic betaine-homocysteine methyltransferase (Bhmt), glycine N-methyltransferase (Gnmt) and cystathionine beta synthase (CBS) gene expression. In contrast, creatine supplementation promoted a 28 % reduction of tumor weight (P < 0.05). Plasma Hcy (C 6.1 ± 0.6, T 10.3 ± 1.5, TCr 6.3 ± 0.9, µmol/L) and hepatic oxidative stress were lower in the TCr group compared to T. Creatine supplementation was unable to decrease Hcy concentration and to increase SAM/SAH ratio in tumor tissue. These data suggest that creatine effects on hepatic impaired Hcy metabolism promoted by tumor cell inoculation are responsible to decrease plasma Hcy in tumor-bearing rats. In conclusion, Walker-256 tumor growth is associated with progressive hyperhomocysteinemia, body weight loss and liver oxidative stress in rats. Creatine supplementation, however, prevented these tumor-associated perturbations.