Doxorubicin causes cachexia, sarcopenia, and frailty characteristics in mice.

While chemotherapy treatment can be lifesaving, it also has adverse effects that negatively impact the quality of life. To investigate the effects of doxorubicin chemotherapy on body weight loss, strength and muscle mass loss, and physical function impairments, all key markers of cachexia, sarcopenia, and frailty. Seventeen C57/BL/6 mice were allocated into groups. 1) Control (n = 7): mice were exposed to intraperitoneal (i.p.) injections of saline solution. 2) Dox (n = 10): mice were exposed to doxorubicin chemotherapy cycles (total dose of 18 mg/kg divided over 15 days). The body weight loss and decreased food intake were monitored to assess cachexia. To assess sarcopenia, we measured muscle strength loss using a traction method and evaluated muscle atrophy through histology of the gastrocnemius muscle. To evaluate physical function impairments and assess frailty, we employed the open field test to measure exploratory capacity. Doxorubicin administration led to the development of cachexia, as evidenced by a significant body weight loss (13%) and a substantial decrease in food intake (34%) over a 15-day period. Furthermore, 90% of the mice treated with doxorubicin exhibited sarcopenia, characterized by a 20% reduction in traction strength (p<0,05), a 10% decrease in muscle mass, and a 33% reduction in locomotor activity. Importantly, all mice subjected to doxorubicin treatment were considered frail based on the evaluation of their overall condition and functional impairments. The proposed model holds significant characteristics of human chemotherapy treatment and can be useful to understand the intricate relationship between chemotherapy, cachexia, sarcopenia, and frailty.

Pre and Post-high-intensity Interval Training Delays Colon Tumor Onset in a Syngeneic Mouse Model.

BACKGROUND/AIM: High-intensity interval training (HIIT) can trigger transient anti-tumor cytotoxicity through the mobilization of natural killer cells (NK cells) and myokines. Yet, the effects of HIIT on tumor development and microenvironment are unclear. MATERIALS AND METHODS: Male C57/BL6 mice were administered either MC38 of syngeneic colon cancer cells or vehicle in a single subcutaneous injection. Before injection, the training group completed four weeks of the HIIT program (progressive swimming training, 3/week, 10-12 min, 4-6% of body weight for overload). Following injection, trained mice continued to exercise for two additional weeks. RESULTS: Pre and post-HIIT training was effective in preventing tumor onset (p=0.0065), maintaining body weight gain, and counteracting splenomegaly by 40% compared to the tumor group. However, HIIT had no impact on suppressing tumor growth, modifying final tumor volume, or significantly changing tumor proliferation (Ki-67), connective tissue content, or DNA double-strand damage detected by phospho-histone gamma-H2AX (γ-H2AX). CONCLUSION: Pre and post-HIIT program is feasible for mice carrying a subcutaneous syngeneic tumor and effective in delaying tumor burden; however, HIIT did not alter colon tumor endpoints.

Antioxidant and photoprotective role of latex C-serum from Hevea brasiliensis during 15-week UVB irradiation in male hairless SKH-1 mice.

It is known that UVB radiation induces several adverse skin alterations starting from simple photoaging to skin cancer. In addition, it was demonstrated that reactive oxygen species (ROS) were found to be related to cancer development and progression. The aim of study was to examine whether male hairless (SKH-1) mice (Mus musculus) that were subchronically exposed to UVB radiation presented with actinic keratosis (AK) and squamous cell carcinoma lesions, and that treatment with latex C-serum cream significantly prevented abnormal skin development. Data demonstrated for the first time the photoprotective activity of latex C-serum extracted from the rubber tree Hevea brasiliensis var. subconcolor Ducke. Latex C-serum prevented the progression of AK to squamous cell carcinoma in SKH-1 mice, indicating that mice topically treated with latex C-serum presented only AK lesions and treatment with the highest concentration (10%) significantly reduced epidermal thickness, suggesting diminished cell proliferation. Latex C-serum protected the skin of mice against oxidative stress damage, increasing catalase (CAT) activity, regenerating glutathione (GSH) levels, lowering thiobarbituric acid-reactive species (TBARS) production and regenerating the total antioxidant capacity (TAC) of the skin. Evidence that UV radiation in skin induced systemic alterations and erythrocytic analysis indicated that latex C-serum increased CAT activity and GSH levels. Taken together these data indicate that latex C-serum plays an important antioxidant and photoprotective role, preventing serious damage to the skin following exposure to UVB radiation.

Statin protects men but not women with HIV against loss of muscle mass, strength, and physical function: a pilot study.

Statins are cholesterol-lowering drugs commonly used among people with HIV, associated with an increased risk of myopathies. Considering that cardiovascular disease, statin therapy, and sarcopenia are independently prevalent in people with HIV, clarity on the potential benefits or harms of statin therapy on muscle health is useful to provide insight into ways to maximize skeletal muscle health and minimize CVD risk in this population. We aimed to study the effects of statin therapy on strength, muscle mass, and physical function parameters in people with HIV. This was a pilot cross-sectional study. People with HIV on continuous statin therapy (n = 52) were paired 1:1 according to age (people with HIV 53.9 ± 8.2 and people with HIV on statins 53.9 ± 8.4 years), sex, body mass index (Body mass index, people with HIV 28.6 ± 5.3 and people with HIV on statins 28.8 ± 6.3 kg/m2), and race with people with HIV not using statin (n = 52). Participants were evaluated for muscle strength (i.e. handgrip strength), lean and fat body mass (using bioelectric impedance analysis), and physical function (i.e. Short Physical Performance Battery-SPPB). Isokinetic strength and appendicular lean mass (using dual-energy X-ray absorptiometry), more accurate strength and body composition measures, were determined in 38% of the participants. Overall, statin usage does not exacerbated loss of muscle strength (32.2 ± 11.5 vs. 30.3 ± 9.6 kg, p > 0.05) muscle mass (7.6 ± 1.8 vs. 7.7 ± 1.1 kg/m2, p > 0.05), and impaired physical performance (10.1 ± 1.8 vs. 9.7 ± 2.1 points, p > 0.05) of PLWH. When analyzed by sex, men living with HIV on statins usage presented higher appendicular muscle mass (28.4 ± 3.1 vs. 26.2 ± 4.9 kg, p < 0.05) handgrip strength (42.1 ± 8.8 vs. 37.1 ± 8.3 kg, p < 0.05) and physical function through SPPB score (10.9 ± 1.3 vs. 9.5 ± 2.1, p < 0.05) than men living with HIV not on statins treatment. The same protection was not observed in women. This data was demonstrated when muscle mass and strength were determined clinically (i.e. handgrip strength and electrical impedance) and when more precise laboratory measurements of muscle mass and strength were conducted (i.e. isokinetic strength and DXA scans). Statin does not exacerbate muscle wasting, strength loss, or muscle dysfunction among people with HIV. Indeed, statins may protect men, but not woman with HIV against HIV and antiretroviral therapy-induced loss of muscle mass and strength.

Role of papillary thyroid carcinoma patients with Hashimoto thyroiditis: evaluation of oxidative stress and inflammatory markers

Purpose Papillary thyroid carcinoma (PTC) is the most frequent subtype of thyroid cancer; Hashimoto's thyroiditis (HT), autoimmune disease, commonly affects the thyroid gland; there is possibly a correlation between both, but the exact mechanisms that involve this relationship are still under debate. Since oxidative stress (OS) and the inflammatory environment participate in the development of several types of cancer, the objective of the present study was to establish the microenvironment and systemic participation of OS and inflammatory markers in patients with PTC and HT. Methods Blood and tissue samples were collected from 115 patients: BENIGN (n = 63); PTC (n = 27); HT (n = 15) and PTC + HT (n = 10), and sixty-three were samples from healthy individuals (control group). Results Superoxide dismutase, Catalase, reduced Glutathione, markers of lipid peroxidation and inflammation were evaluated in blood. Immunohistochemistry was performed on 3-nitrotyrosine, 4-hydroxynonenal, Ki-67 and VEGF. The results indicate that antioxidant enzymes were more active in groups with thyroid disorders compared to control, while the concentration of Reduced glutathione was reduced in BENIGN and PTC groups. When PTC and PTC + HT groups were analyzed, no significant differences were found in relation to the antioxidant defense and inflammatory markers. The ability to contain the induced lipid peroxidation was lower and a high level of malondialdehyde was observed in the PTC group. All immunohistochemical markers had higher scores in the PTC group compared to PTC + HT. Conclusion There was a more pronounced presence of OS and a greater activity of cell proliferation and angiogenesis markers in PTC than in PTC + HT group (AU)

Creatine supplementation protects against diet-induced non-alcoholic fatty liver but exacerbates alcoholic fatty liver.

AIMS: This work investigated the effects of creatine supplementation on different pathways related to the pathogenesis of non-alcoholic fatty liver disease and alcoholic liver disease. MAIN METHODS: To induce alcoholic liver disease, male Swiss mice were divided into three groups: control, ethanol and ethanol supplemented with creatine. To induce non-alcoholic fatty liver disease, mice were divided into three groups: control, high-fat diet and high-fat diet supplemented with creatine. Each group consisted of eight animals. In both cases, creatine monohydrate was added to the diets (1 %; weight/vol). KEY FINDINGS: Creatine supplementation prevented high-fat diet-induced non-alcoholic fatty liver disease progression, demonstrated by attenuated liver fat accumulation and liver damage. On the other hand, when combined with ethanol, creatine supplementation up-regulated key genes related to ethanol metabolism, oxidative stress, inflammation and lipid synthesis, and exacerbated ethanol-induced liver steatosis and damage, demonstrated by increased liver fat accumulation and histopathological score, as well as elevated oxidative damage markers and inflammatory mediators. SIGNIFICANCE: Our results clearly demonstrated creatine supplementation exerts different outcomes in relation to non-alcoholic fatty liver disease and alcoholic liver disease, namely it protects against high-fat diet-induced non-alcoholic fatty liver disease but exacerbates ethanol-induced alcoholic liver disease. The exacerbating effects of the creatine and ethanol combination appear to be related to oxidative stress and inflammation-mediated up-regulation of ethanol metabolism.

Resistance Training Attenuates Activation of STAT3 and Muscle Atrophy in Tumor-Bearing Mice.

Purpose: Although the role of signal transducers and activators of transcription (STAT3) in cachexia due to the association of circulating IL-6 and muscle wasting has been extensively demonstrated, the effect of resistance training on STAT3 in mediating muscle atrophy in tumor-bearing mice is unknown. The aim of this study is to investigate the effects of resistance exercise training on inflammatory cytokines and oxidative-mediated STAT3 activation and muscle loss prevention in tumor-bearing mice. Methods: Male Swiss mice were inoculated with Ehrlich tumor cells and exposed or not exposed to resistance exercise protocol of ladder climbing. Skeletal muscle STAT3 protein content was measured, compared between groups, and tested for possible association with plasma interleukins and local oxidative stress markers. Components of the ubiquitin-proteasome and autophagy pathways were assessed by real-time PCR or immunoblotting. Results: Resistance training prevented STAT3 excessive activation in skeletal muscle mediated by the overabundance of plasma IL-6 and muscle oxidative stress. These mechanisms contributed to preventing the increased key genes and proteins of ubiquitin-proteasome and autophagy pathways in tumor-bearing mice, such as Atrogin-1, LC3B-II, and Beclin-1. Beyond preventing muscle atrophy, RT also prevented strength loss and impaired locomotor capacity, hallmarks of sarcopenia. Conclusion: Our results suggest that STAT3 inhibition is central in resistance exercise protective effects against cancer-induced muscle atrophy and strength loss.

Role of papillary thyroid carcinoma patients with Hashimoto thyroiditis: evaluation of oxidative stress and inflammatory markers.

PURPOSE: Papillary thyroid carcinoma (PTC) is the most frequent subtype of thyroid cancer; Hashimoto's thyroiditis (HT), autoimmune disease, commonly affects the thyroid gland; there is possibly a correlation between both, but the exact mechanisms that involve this relationship are still under debate. Since oxidative stress (OS) and the inflammatory environment participate in the development of several types of cancer, the objective of the present study was to establish the microenvironment and systemic participation of OS and inflammatory markers in patients with PTC and HT. METHODS: Blood and tissue samples were collected from 115 patients: BENIGN (n = 63); PTC (n = 27); HT (n = 15) and PTC + HT (n = 10), and sixty-three were samples from healthy individuals (control group). RESULTS: Superoxide dismutase, Catalase, reduced Glutathione, markers of lipid peroxidation and inflammation were evaluated in blood. Immunohistochemistry was performed on 3-nitrotyrosine, 4-hydroxynonenal, Ki-67 and VEGF. The results indicate that antioxidant enzymes were more active in groups with thyroid disorders compared to control, while the concentration of Reduced glutathione was reduced in BENIGN and PTC groups. When PTC and PTC + HT groups were analyzed, no significant differences were found in relation to the antioxidant defense and inflammatory markers. The ability to contain the induced lipid peroxidation was lower and a high level of malondialdehyde was observed in the PTC group. All immunohistochemical markers had higher scores in the PTC group compared to PTC + HT. CONCLUSION: There was a more pronounced presence of OS and a greater activity of cell proliferation and angiogenesis markers in PTC than in PTC + HT group.

Effect of running exercise on titanium dioxide (TiO2)-induced chronic arthritis and sarcopenia in mice. A titanium prosthesis loosening injury model study.

AIMS: This study aimed to investigate if titanium dioxide (TiO2) joint administration is a useful pre-clinical model to study sarcopenia-related chronic arthritis, and if exercise is a useful therapeutic approach against the pathogenesis of TiO2-induced arthritis and sarcopenia in mice. MAIN METHODS: Two experiments were conducted. Firstly, 36 female Swiss mice were randomly divided into a control group (n = 12) and two groups who received intra-articular TiO2 injections of 0.3-mg (n = 12) and 3-mg (n = 12), respectively. Mice were euthanized 4 and 8 weeks after TiO2 injections. Based on data of the first experiment, mice were exposed to four groups: control (C, n = 10), exercised (Ex, n = 10), injected with 3-mg of TiO2 (TiO2, n = 10), and injected with 3-mg of TiO2 and exercised (TiO2 + Ex, n = 10) for a total of 8-weeks. KEY FINDINGS: Eight-week of 3 mg of TiO2 joint administration promoted characteristics of chronic inflammation such as elevated histopathological score, inflammation, edema and pain. Hallmarks of sarcopenia were also observed such as muscle atrophy and loss of strength. Furthermore, voluntary exercise running reduced TiO2-induced chronic inflammation and pain, attenuating chronic arthritis-related muscle atrophy, strength loss and impairment of locomotion capacity. In addition, exercise was also able to prevent TiO2-induced collagen degradation, an important marker of functional and structural integrity loss of cartilage and chronic arthritis disease progression. SIGNIFICANCE: TiO2 joint administration mimed titanium prosthesis release-induced joint chronic arthritis and sarcopenia-related chronic arthritis, disturbances that were attenuated by voluntary exercise.

Caffeine improves the cytotoxic effect of dacarbazine on B16F10 murine melanoma cells.

OBJECTIVE: Caffeine has been studied as a potentiating agent in chemotherapy against some types of cancer, but there are few reports on its effects on melanoma. This study aimed to investigate caffeine's ability to enhance the effects of dacarbazine in vitro. MATERIALS AND METHODS: Murine melanoma B16F10 cells were treated 24 h with 1-40 µM caffeine. We evaluated cytotoxicity, DNA damage, apoptosis, and oxidative lesion induced by dacarbazine associated with caffeine. The metabolization of these drugs, as well as immunocytochemical labeling, were also evaluated. CONCLUSIONS: The pre-treatment with caffeine showed to be more effective. Caffeine potentiated dacarbazine-induced cytotoxic effects by increasing dacarbazine biotransformation, apoptosis, DNA damage, and malondialdehyde levels; also, caffeine reduced Ki67 and ERK1/2 nuclear labeling and increased p53 labeling in B16F10 cells. In our experiment, caffeine promoted modifications associated with dacarbazine metabolism by viable cells potentiating this antineoplastic drug. These promising results should be further evaluated in experimental models in vivo.

Metformin pretreatment reduces effect to dacarbazine and suppresses melanoma cell resistance.

Oxidative stress role on metformin process of dacarbazine (DTIC) inducing resistance of B16F10 melanoma murine cells are investigated. To induce resistance to DTIC, murine melanoma cells were exposed to increasing concentrations of dacarabazine (DTIC-res group). Metformin was administered before and during the induction of resistance to DTIC (MET-DTIC). The oxidative stress parameters of the DTIC-res group showed increased levels of malondialdehyde (MDA), thiol, and reduced nuclear p53, 8-hydroxy-2'-deoxyguanosine (8-OH-DG), nuclear factor kappa B (NF-ĸB), and Nrf2. In presence of metformin in the resistant induction process to DTIC, (MET-DTIC) cells had increased antioxidant thiols, MDA, nuclear p53, 8-OH-DG, Nrf2, and reducing NF-ĸB, weakening the DTIC-resistant phenotype. The exclusive administration of metformin (MET group) also induced the cellular resistance to DTIC. The MET group presented high levels of total thiols, MDA, and reduced percentage of nuclear p53. It also presented reduced nuclear 8-OH-DG, NF-ĸB, and Nrf2 when compared with the control. Oxidative stress and the studied biomarkers seem to be part of the alterations evidenced in DTIC-resistant B16F10 cells. In addition, metformin administration is able to play a dual role according to the experimental protocol, preventing or inducing a DTIC-resistant phenotype. These findings should help future research with the aim of investigating DTIC resistance in melanoma.

Resistance Training's Ability to Prevent Cancer-induced Muscle Atrophy Extends Anabolic Stimulus.

PURPOSE: This study aimed to determine the role of mammalian target of rapamycin (mTORC1) activation and catabolic markers in resistance training's (RT) antiatrophy effect during cachexia-induced muscle loss. METHODS: Myofiber atrophy was induced by injecting Walker 256 tumor cells into rats exposed or not exposed to the RT protocol of ladder climbing. The role of RT-induced anabolic stimulation was investigated in tumor-bearing rats with the mTORC1 inhibitor rapamycin, and cross-sectional areas of skeletal muscle were evaluated to identify atrophy or hypertrophy. Components of the mTORC1 and ubiquitin-proteasome pathways were assessed by real-time polymerase chain reaction or immunoblotting. RESULTS: Although RT prevented myofiber atrophy and impaired the strength of tumor-bearing rats, in healthy rats, it promoted activated mTORC1, as demonstrated by p70S6K's increased phosphorylation and myofiber's enlarged cross-sectional area. However, RT promoted no changes in the ratio of p70S6K to phospho-p70S6K protein expression while prevented myofiber atrophy in tumor-bearing rats. Beyond that, treatment with rapamycin did not preclude RT's preventive effect on myofiber atrophy in tumor-bearing rats. Thus, RT's ability to prevent cancer-induced myofiber atrophy seems to be independent of mTORC1's and p70S6K's activation. Indeed, RT's preventive effect on cancer-induced myofiber atrophy was associated with its capacity to attenuate elevated tumor necrosis factor α and interleukin 6 as well as to prevent oxidative damage in muscles and an elevated abundance of atrogin-1. CONCLUSIONS: By inducing attenuated myofiber atrophy independent of mTORC1's signaling activation, RT prevents muscle atrophy during cancer by reducing inflammation, oxidative damage, and atrogin-1 expression.

Oxidative Stress in Caffeine Action on the Proliferation and Death of Human Breast Cancer Cells MCF-7 and MDA-MB-231.

To investigate the effects of caffeine on the proliferation and death of human breast cancer cells MCF-7 and MDA-MB-231. Cells were exposed to 1, 2.5, 5 and 10 mM of caffeine during 24 h, and oxidative stress (OS), cell proliferation and death, metabolic activity and DNA lesions were evaluated in the collected samples. Caffeine was cytotoxic to the cell lines analyzed, reducing cell proliferation and viability by interfering with the cellular metabolism and with lysosomal function. Although the cells presented different behaviors to treatment, in both cell lines, the drug induced OS and predominantly apoptosis. MCF-7 cells responded to OS induction (lipid peroxidation) increasing their antioxidant defenses. However, the OS generated induced oxidative DNA lesions, a finding not observed in MDA-MB-231 cells. The association of different scavengers with caffeine did not result in the recovery of cell viability, which suggests that it is not possible to attribute the caffeine induction of OS to only one of the specific ROS analyzed (superoxide anion, singlet oxygen and peroxyl radical). These results are promising and suggest that caffeine may be a good target for studies to prove its usefulness as an adjuvant in breast cancer treatment.

Antiviral therapies: advances and perspectives.

Viral infections cause high morbidity and mortality, threaten public health, and impose a socioeconomic burden. We have seen the recent emergence of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2), the causative agent of COVID-19 that has already infected more than 29 million people, with more than 900 000 deaths since its identification in December 2019. Considering the significant impact of viral infections, research and development of new antivirals and control strategies are essential. In this paper, we summarize 96 antivirals approved by the Food and Drug Administration between 1987 and 2019. Of these, 49 (51%) are used in treatments against human immunodeficiency virus (HIV), four against human papillomavirus, six against cytomegalovirus, eight against hepatitis B virus, five against influenza, six against herpes simplex virus, 17 against hepatitis C virus and one against respiratory syncytial virus. This review also describes future perspectives for new antiviral therapies such as nanotechnologies, monoclonal antibodies and the CRISPR-Cas system. These strategies are suggested as inhibitors of viral replication by various means, such as direct binding to the viral particle, blocking the infection, changes in intracellular mechanisms or viral genes, preventing replication and virion formation. We also observed that a large number of viral agents have no therapy available and the majority of those approved in the last 32 years are restricted to some groups, especially anti-HIV. Additionally, the emergence of new viruses and strains resistant to available antivirals has necessitated the formulation of new antivirals.

Low Agreement Between Initial and Revised European Consensus on Definition and Diagnosis of Sarcopenia Applied to People Living With HIV.

BACKGROUND: In 2019, the European Working Group on Sarcopenia in Older People (EWGSOP2) proposed low muscle strength as the primary outcome for sarcopenia diagnosis instead of low muscle mass, as proposed in 2010 (EWGSOP1). Therefore, the aim of this study was to compare the prevalence of sarcopenia using both EWGSOP1 and EWGSOP2 operational definitions in people living with HIV (PLHIV) and to determine the agreement and correlation between different tests proposed by EWGSOP2. SETTING: Cross-sectional study, where 302 PLHIV (151 men), 51.7 ± 9.0 years old were evaluated for the presence of sarcopenia using both EWGSOP1 and EWGSOP2 operational definitions. METHODS: Appendicular skeletal muscle was estimated using bioimpedance analysis. Handgrip strength, chair stand, gait speed, and static balance were used as muscle function measures. Agreement was determined using Cohen kappa and Pearson correlation coefficient was calculated. RESULTS: Sarcopenia prevalence was 4.3% using EWGSOP1 and 1.0% using EWGSOP2. Agreement for sarcopenia diagnosis between EWGSOP1 and EWGSOP2 was fair (k = 0.37, P < 0.01). From the 13 cases of sarcopenia diagnosed using EWGSOP1, only 3 cases (23.1%) were also diagnosed using EWGSOP2. A medium correlation (r = -0.32, P < 0.01) and poor agreement (k = 0.14, P < 0.01) between muscle strength tests (handgrip strength and chair stand) were observed. Concordance between handgrip and chair stand was observed in 11 participants only, whereas 65 participants were considered to have low muscle strength using chair stand but not using handgrip. CONCLUSIONS: Lower sarcopenia prevalence using EWGSOP2 and low agreement between EWGSOP1 and EWGSOP2 operational definitions in diagnosing sarcopenia were observed in PLHIV.

The progression of metastatic melanoma augments a pro-oxidative milieu locally but not systemically.

Malignant melanoma is the most dangerous form of skin cancer. Despite new therapies for melanoma treatment, effective therapy is mainly limited by excessive metastasis. Currently, the factors determining metastasis development are not elucidated, but oxidative stress was suggested to be involved. To this end, we analyzed oxidative stress parameters during the metastatic development using the syngeneic B16F10 melanoma model. An increase in blood plasma lipid peroxidation occurred at the earliest stage of the disease, with a progressive decrease in oxidative damage and an increase in antioxidant defense. Vice versa, increased lipid peroxidation and 3-nitrotyrosine, and decreased antioxidant parameters were observed in the metastatic nodules throughout the disease. This was concomitant with a progressive increase in vascular endothelial growth factor and proliferating cell nuclear antigen. We conclude that the oxidative stress in the bloodstream decreases during the metastatic process and that nitrosative stress increases during the proliferation and growth of metastatic nodules in the tumor microenvironment. These results will help to better understand the role of oxidative stress during melanoma metastasis.

Creatine supplementation does not promote tumor growth or enhance tumor aggressiveness in Walker-256 tumor-bearing rats.

OBJECTIVES: This study aimed to analyze the effect of creatine (Cr) supplementation on tumor microenvironment, evaluating the parameters of tumor aggressiveness. METHODS: Sixteen male Wistar rats were randomly assigned to 2 groups (n = 8/group): Tumor-bearing (T) and tumor-bearing supplemented with Cr (TCr). Cr supplementation was provided in drinking water for a total of 21 d. After 11 d of Cr supplementation (TCr group) or water (T group), Walker-256 tumor cells were inoculated subcutaneously in the right flank of all rats, which kept receiving Cr supplementation (TCr group) or water (T group) for 10 more days. The total period of the experiment was 21 d. RESULTS: Tumor weight corresponded with approximately 3.5% ± 0.9% of animal body weight in the T group. Cr supplementation did not accelerate tumor growth or increase tumor size. The histopathological analysis demonstrated the presence of nuclear pleomorphisms and atypical nuclei, with the presence of low-differentiated tumor cells, in both groups. Cr supplementation did not alter apoptosis and cell proliferation markers, nor tumor capsule thickness and viable tumor area. CONCLUSIONS: Cr supplementation in Walker-256 tumor-bearing rats did not induce significant changes in tumor development, and did not interfere with the parameters of tumor aggressiveness, such as the level of cell differentiation and proliferation.

Patterns of cell death induced by metformin in human MCF-7 breast cancer cells.

The ability to evade apoptosis is an important mechanism of drug resistance and tumor progression in breast cancer. The induction of different pathways of cell death could be an important strategy to limit tumor progression. Metformin, a drug used to treat type two diabetes, has demonstrated promising results in breast cancer experiments. However, little is known about the patterns of cell death induced by this drug. We analyzed the involvement of apoptosis, necroptosis and ferroptosis in the toxicity of metformin in MCF-7 cells, evaluating proliferation, viability and oxidative stress. It was used different inhibitors of cell death: Z-VAD, a pan-caspase inhibitor that blocks apoptosis; Necrostatin-1, which inhibits RIPK1 activity and blocks necroptosis; and the iron chelator, deferoxamine, that chelates iron and prevents ferroptosis. The participation of oxidative stress was analyzed through the evaluation of total thiols, reduced glutathione (GSH) and malondialdehyde (MDA). Our results showed that metformin increased cell death, reduced proliferation, thiol and GSH and increased MDA in cells. After the association between metformin and Z-VAD or Necrostatin-1, the drug toxicity was abolished. Ferroptosis did not significantly enrolled in metformin action against MCF-7 cells. The preservation of cellular antioxidants was found in all situations that cell death was blocked. Together, these results reveals that metformin induces necroptosis and apoptosis in MCF-7 cells and oxidative stress generation play a role in these two pathways of cell death. This information could help future studies to improve strategies to breast cancer treatment.