Alternagin-C, an alpha2beta1 integrin ligand, attenuates collagen-based adhesion, stimulating the metastasis suppressor 1 expression in triple-negative breast tumor cells.

Triple-negative breast cancer has an aggressive clinical course and its treatment has been challenging due to high metastatic risk. Molecular targets have been sought to provide better strategies for this type of cancer. Integrins are cell adhesion receptors involved in tumor progression and α2ß1 integrin, a collagen receptor, has a key role in breast metastasis. Disintegrins, a family of proteins from snake venoms, selectively block the function of integrin receptors. Alternagin-C (ALT-C), a disintegrin-like protein purified from Bothrops alternatus venom, binds to α2ß1 integrin, attenuating inflammation and angiogenesis, and decreasing metalloprotease levels in the tumor microenvironment, which suggests anti-metastatic effects. However, its mechanisms of action in metastatic tumor cells have not been fully explored. Here, we investigated ALT-C effects in a triple-negative breast cancer cell line (MDA-MB-231) to elucidate how α2ß1 integrin affects cellular adhesion, migration and gene expression related to metastasis. We observed that ALT-C attenuated cell adhesion of MDA-MB-231 cells to collagen I. α2 integrin subunit silencing in MDA-MB-231 cells did not inhibit cell adhesion and migration to collagen I, indicating that other integrins play a crucial role in cell motility for this cell line. ALT-C also stimulated the metastasis suppressor 1 (MTSS1) expression and decreased metalloproteases MMP9 and MMP2. Therefore, we suggest that ALT-C contributes to impair metastasis, preventing extracellular matrix degradation and tumor attachment to collagen I, increasing MTSS1. This study is the first to elucidate the anti-metastatic mechanism involving a disintegrin-like protein from snake venom targeting α2ß1 integrin and stimulating a metastasis suppressor.

Resistance training variable manipulations are less relevant than intrinsic biology in affecting muscle fiber hypertrophy.

We aimed to investigate whether muscle fiber cross-sectional area (fCSA) and associated molecular processes could be differently affected at the group and individual level by manipulating resistance training (RT) variables. Twenty resistance-trained subjects had each leg randomly allocated to either a standard RT (RT-CON: without specific variables manipulations) or a variable RT (RT-VAR: manipulation of load, volume, muscle action, and rest interval at each RT session). Muscle fCSA, satellite cell (SC) pool, myonuclei content, and gene expression were assessed before and after training (chronic effect). Gene expression was assessed 24 h after the last training session (acute effect). RT-CON and RT-VAR increased fCSA and myonuclei domain in type I and II fibers after training (p < 0.05). SC and myonuclei content did not change for both conditions (p > 0.05). Pax-7, MyoD, MMP-2 and COL3A1 (chronic) and MGF, Pax-7, and MMP-9 (acute) increased similar for RT-CON and RT-VAR (p < 0.05). The increase in acute MyoG expression was significantly higher for the RT-VAR than RT-CON (p < 0.05). We found significant correlation between RT-CON and RT-VAR for the fCSA changes (r = 0.89). fCSA changes were also correlated to satellite cells (r = 0.42) and myonuclei (r = 0.50) changes. Heatmap analyses showed coupled changes in fCSA, SC, and myonuclei responses at the individual level, regardless of the RT protocol. The high between and low within-subject variability regardless of RT protocol suggests that the intrinsic biological factors seem to be more important to explain the magnitude of fCSA gains in resistance-trained subjects.

Associations between sociodemographic factors and physical activity and sedentary behaviors in adults with chronic diseases during COVID-19 pandemic.

The pandemic of the new coronavirus (COVID-19) may be affecting the physical activity (PA) level in much of the population. This study aimed to investigate the prevalence of physical inactivity and sedentary behavior (SB) among adults with chronic diseases and their associations with sociodemographic factors during the COVID-19 pandemic. This cross-sectional study included 249 participants (age: 18-91 years; 61.4% female) with chronic conditions and attended the Family Health Strategy program in a small town in Brazil. Data were collected between 2020-07-13 and 2020-07-24 by face-to-face interviews. Self-reported PA, sitting time, chronic diseases, medication use, sociodemographic data, and self-isolation adherence were obtained by questionnaire. During this specific time point of the COVID-19 pandemic, 71.5% of participants did not meet the PA recommendations (≥500 METs-min/week), and the prevalence of SB risk (≥4 h sitting) was 62.7%. Adjusted logistic regression indicated that male participants (odds ratio [OR]: 1.89 [95% CI 1.02-3.53]), living alone (OR: 2.92 [95% CI 1.03-8.30]) or in a two-person household (OR: 2.32 [95% CI 1.16-4.63]), and those who reported sometimes performing self-isolation (OR: 3.07 [95% CI 1.47-6.40]) were more likely to meet the minimum PA recommendations. Current smokers had a lower odds (OR: 0.36 [95% CI 0.14-0.95]) of meeting the PA recommendations. Older participants (OR: 2.18 [95% CI 1.06-4.50]) and those who had multimorbidity (OR: 1.92 [95% CI 1.07-3.44]) were more likely to have a higher degree of SB. There is an urgent need to mitigate physical inactivity and SB, and public health interventions must take into account sociodemographic status.

Benefits of resistance training on body composition and glucose clearance are inhibited by long-term low carbohydrate diet in rats.

BACKGROUND/OBJECTIVES: Regular exercise training is effective to altering many markers of metabolic syndrome and its effects are strongly influenced by the type of consumed diet. Nowadays, resistance training (RT) has been frequently associated with low-carbohydrate high-fat diet (LCD). After long term these diets causes body weight (BW) regain with deleterious effects on body composition and metabolic risk factors. The effects of RT associated with long-term LCD on these parameters remain unexplored. We aimed to investigate the effects of RT when associated with long-term LCD on BW, feed efficiency, body composition, glucose homeostasis, liver parameters and serum biochemical parameters during BW regain period in rats. SUBJECTS/METHODS: Male Sprague-Dawley rats were fed with LCD (LC groups) or standard diet (STD) (ST groups). After 10 weeks-diet animals were separated into sedentary (Sed-LC and Sed-ST) and resistance-trained (RT-LC and RT-ST) groups (N = 8/group). RT groups performed an 11-week climbing program on a ladder with progressive load. Dual x-ray absorptiometry, glucose tolerance tests and insulin tolerance tests were performed at weeks 10 and 20. Liver and serum were collected at week 21. RESULTS: RT reduced feed efficiency, BW gain, liver fat and total and LDL cholesterol, and improved body composition and glucose clearance in animals fed on STD. In those fed with LCD, RT reduced caloric intake, BW regain, liver fat and serum triglycerides levels. However, improvement in body composition was inhibited and bone mineral density and glucose clearance was further impaired in this association. CONCLUSIONS: The LCD nullifies the beneficial effects of RT on body composition, glucose homeostasis and impairs some health parameters. Our results do not support the association of RT with LCD in a long term period.

Effects of resistance training and estrogen replacement on adipose tissue inflammation in ovariectomized rats.

Estrogen deficiency is directly related to central obesity and low-grade inflammation. Hormonal replacement and exercise training are both able to decrease fat accumulation and inflammation in postmenopausal women. However, the efficiency of resistance training (RT) and estrogen replacement (ER) in minimizing adiposity and inflammation in the visceral adipose tissue (VAT) of ovariectomized (OVX) rats has not yet been elucidated. In this study, Sprague-Dawley rats were divided into the following 6 groups: sham-operated sedentary (Sham-Sed), OVX-Sed, Sham-RT, OVX-RT, OVX-Sed-ER, and OVX-RT-ER groups. ER was performed by implanting silastic capsules containing 17ß-estradiol. For RT, the animals were required to climb a 1.1-m vertical ladder with conical flasks containing weights attached to their tails for 12 weeks. Histological analyses were used to evaluate morphological changes. Gene expression levels were determined by quantitative real-time reverse transcriptase polymerase chain reaction, and protein concentrations were determined using Multiplex/Luminex assays. Ovariectomy increased the body mass (BM), adipocyte area, and inflammation in the VAT, the latter of which was indicated by reduced interleukin-10 (48%) and increased tumor necrosis factor (TNF)-α concentration (∼3%). RT efficiently decreased BM, adipocyte area, and inflammation in the OVX groups. The combination of RT and ER decreased BM (19%) and the TNF-α concentration (18%) and increased the gene and protein expression levels of adiponectin (173% and 18%). These results indicate that RT and the combination of RT and ER are efficient strategies for reducing the BM and improving the inflammatory status of OVX rats.

Estrogen deficiency in ovariectomized rats: can resistance training re-establish angiogenesis in visceral adipose tissue?

OBJECTIVE: The purpose of this study was to investigate the effects of resistance training on angiogenesis markers of visceral adipose tissue in ovariectomized rats. METHOD: Adult Sprague-Dawley female rats were divided into four groups (n=6 per group): sham-sedentary, ovariectomized sedentary, sham-resistance training and ovariectomized resistance training. The rats were allowed to climb a 1.1-m vertical ladder with weights attached to their tails and the weights were progressively increased. Sessions were performed three times per week for 10 weeks. Visceral adipose tissue angiogenesis and morphology were analyzed by histology. VEGF-A mRNA and protein levels were analyzed by real-time PCR and ELISA, respectively. RESULTS: Ovariectomy resulted in higher body mass (p=0.0003), adipocyte hypertrophy (p=0.0003), decreased VEGF-A mRNA (p=0.0004) and protein levels (p=0.0009), and decreased micro-vascular density (p=0.0181) in the visceral adipose tissue of the rats. Resistance training for 10 weeks was not able to attenuate the reduced angiogenesis in the visceral adipose tissue of the ovariectomized rats. CONCLUSION: Our findings indicate that the resistance training program used in this study could not ameliorate low angiogenesis in the visceral adipose tissue of ovariectomized rats.

Estrogen deficiency in ovariectomized rats: can resistance training re-establish angiogenesis in visceral adipose tissue?

OBJECTIVE: The purpose of this study was to investigate the effects of resistance training on angiogenesis markers of visceral adipose tissue in ovariectomized rats. METHOD: Adult Sprague-Dawley female rats were divided into four groups (n=6 per group): sham-sedentary, ovariectomized sedentary, sham-resistance training and ovariectomized resistance training. The rats were allowed to climb a 1.1-m vertical ladder with weights attached to their tails and the weights were progressively increased. Sessions were performed three times per week for 10 weeks. Visceral adipose tissue angiogenesis and morphology were analyzed by histology. VEGF-A mRNA and protein levels were analyzed by real-time PCR and ELISA, respectively. RESULTS: Ovariectomy resulted in higher body mass (p=0.0003), adipocyte hypertrophy (p=0.0003), decreased VEGF-A mRNA (p=0.0004) and protein levels (p=0.0009), and decreased micro-vascular density (p=0.0181) in the visceral adipose tissue of the rats. Resistance training for 10 weeks was not able to attenuate the reduced angiogenesis in the visceral adipose tissue of the ovariectomized rats. CONCLUSION: Our findings indicate that the resistance training program used in this study could not ameliorate low angiogenesis in the visceral adipose tissue of ovariectomized rats.

Effects of ovariectomy and resistance training on oxidative stress markers in the rat liver.

OBJECTIVE: The objective of this study was to assess the effects of resistance training on oxidative stress markers in the livers of ovariectomized rats. METHOD: Adult Sprague-Dawley rats were divided into the following four groups (n = 8 per group): sham-operated sedentary, ovariectomized sedentary, sham-operated resistance training, and ovariectomized resistance training. During the resistance training period, the animals climbed a 1.1-m vertical ladder with weights attached to their tails; the sessions were conducted 3 times per week, with 4-9 climbs and 8-12 dynamic movements per climb. The oxidative stress was assessed by measuring the levels of reduced glutathione and oxidized glutathione, the enzymatic activity of catalase and superoxide dismutase, lipid peroxidation, vitamin E concentrations, and the gene expression of glutathione peroxidase. RESULTS: The results showed significant reductions in the reduced glutathione/oxidized glutathione ratio (4.11±0.65 nmol/g tec), vitamin E concentration (55.36±11.11 nmol/g), and gene expression of glutathione peroxidase (0.49±0.16 arbitrary units) in the livers of ovariectomized rats compared with the livers of unovariectomized animals (5.71±0.71 nmol/g tec, 100.14±10.99 nmol/g, and 1.09±0.54 arbitrary units, respectively). Moreover, resistance training for 10 weeks was not able to reduce the oxidative stress in the livers of ovariectomized rats and induced negative changes in the hepatic anti-oxidative/oxidative balance. CONCLUSION: Our findings indicate that the resistance training program used in this study was not able to attenuate the hepatic oxidative damage caused by ovariectomy and increased the hepatic oxidative stress.

Effects of ovariectomy and resistance training on oxidative stress markers in the rat liver

OBJECTIVE: The objective of this study was to assess the effects of resistance training on oxidative stress markers in the livers of ovariectomized rats. METHOD: Adult Sprague-Dawley rats were divided into the following four groups (n = 8 per group): sham-operated sedentary, ovariectomized sedentary, sham-operated resistance training, and ovariectomized resistance training. During the resistance training period, the animals climbed a 1.1-m vertical ladder with weights attached to their tails; the sessions were conducted 3 times per week, with 4-9 climbs and 8-12 dynamic movements per climb. The oxidative stress was assessed by measuring the levels of reduced glutathione and oxidized glutathione, the enzymatic activity of catalase and superoxide dismutase, lipid peroxidation, vitamin E concentrations, and the gene expression of glutathione peroxidase. RESULTS: The results showed significant reductions in the reduced glutathione/oxidized glutathione ratio (4.11±0.65 nmol/g tec), vitamin E concentration (55.36±11.11 nmol/g), and gene expression of glutathione peroxidase (0.49±0.16 arbitrary units) in the livers of ovariectomized rats compared with the livers of unovariectomized animals (5.71±0.71 nmol/g tec, 100.14±10.99 nmol/g, and 1.09±0.54 arbitrary units, respectively). Moreover, resistance training for 10 weeks was not able to reduce the oxidative stress in the livers of ovariectomized rats and induced negative changes in the hepatic anti-oxidative/oxidative balance. CONCLUSION: Our findings indicate that the resistance training program used in this study was not able to attenuate the hepatic oxidative damage caused by ovariectomy and increased the hepatic oxidative stress. .

Resistance training restores the gene expression of molecules related to fat oxidation and lipogenesis in the liver of ovariectomized rats.

Decreased levels of estrogen are associated with hepatic steatosis (HS), through changes in gene expression of molecules related to fat oxidation and lipogenesis. Both resistance training (RT) and endurance training (ET) prevent HS in ovariectomized (Ovx) rats. However, the molecular events associated with this process were only investigated for ET, but not for RT. Thus, the aim of this study was to investigate the effects of Ovx and RT on the gene expression of molecules related to fat oxidation and lipogenesis in the liver of rats. Sprague-Dawley adult female rats were grouped into four (n = 6 per group): sham-operated sedentary (Sham-Sed); Ovx sedentary (Ovx-Sed); sham-Rt and Ovx-Rt. A 10-week RT period, during which the animals climbed a 1.1-m vertical ladder with weights attached to their tails, was used. The sessions were performed three times a week, with 4-9 climbs and 8-12 dynamic movements per climb. Gene expression was analyzed by RT-PCR by the ∆∆Ct method. The estrogen deficiency associated with ovariectomy decreased the gene expression of molecules related to fat oxidation, carnitine palmitoyltransferase I (53%) and ß-hydroxyacyl-CoA dehydrogenase (27%), and increased molecules related to lipogenesis, sterol regulatory element-binding protein-1c (106%), acetyl-CoA carboxylase (ACC) (72%) and stearoyl CoA desaturase-1 (109%). With the exception of ACC, the ovariectomy-induced changes in the expression of these molecules were restored by RT. The present results indicate that RT has important effects on the prevention of HS in Ovx animals, through changes in gene expression of molecules related to hepatic lipid metabolism.