Effect of Paullinia cupana on MCF-7 breast cancer cell response to chemotherapeutic drugs

Previous studies suggested that certain plants, such as guarana (Paullinia cupana), exert a protective effect against cancer-related fatigue in breast cancer patients undergoing chemotherapy. However, guarana possesses bioactive molecules, such as caffeine and catechin, which may affect the pharmacological properties of antitumor drugs. Therefore, the aim of this study was to evaluate the effects of guarana on breast cancer cell response to 7 chemotherapeutic agents currently used in the treatment of breast cancer. To perform this study, MCF-7 breast cancer cells were cultured under controlled conditions and exposed to 1, 5 and 10 µg/ml guarana concentrations, with and without chemotherapeutics (gemcitabine, vinorelbine, methotrexate, 5-fluorouracil, paclitaxel, doxorubicin and cyclophosphamide). The effect of these treatments on MCF-7 cell viability and proliferation was spectrophotometrically analyzed with the MTT assay. The main results demonstrated an antiproliferative effect of guarana at concentrations of 5 and 10 µg/ml and a significant effect on chemotherapeutic drug action. In general, guarana improved the antiproliferative effect of chemotherapeutic agents, causing a decrease of >40% in cell growth after 72 h of exposure. The results suggested an interaction of guarana with the chemotherapeutic drugs, which requires confirmation by in vivo complementary studies.

In vitro effects of Ala16Val manganese superoxide dismutase gene polymorphism on human white blood cells exposed to methylmercury

Environmental contamination by methylmercury (MeHg) is an enormous public health problem in world regions such as Amazonia. MeHg toxic effects seem to be influenced by environmental and genetic factors. However, few studies have evaluated the genetic influences of MeHg toxicity in humans. Therefore, the aim of this study was to evaluate the genetic influence of Ala16Val manganese superoxide dismutase gene polymorphism (Ala16Val-MnSOD) on the cytotoxic effects of in vitro human leukocytes exposed to MeHg. Subjects were selected from 100 individuals aged 26.4 ± 7.3 years genotyped to Ala16Val-MnSOD polymorphism (AA = 6, VV = 6, and AV = 12) to perform in vitro testing using white blood cells (WBCs). Reactive oxygen species production was measured using 2',7'-dichlorofluorescein diacetate fluorimetric assay, and cell viability was measured using MTT assay on WBC samples from the same subjects that were both exposed and not exposed to MeHg (2.5 µM for 6 h). The results showed that AA- and VV-WBCs exposed to MeHg did not display increased reactive oxygen species levels compared to those in cells that were not exposed. However, AV-leukocytes exposed to MeHg displayed increased ROS levels. Cellular viability comparison among genotypes exposed to MeHg showed that the viability of AA-WBCs was lower than that of VV-WBC, with mean values of 3.46 ± 0.13 and 3.08 ± 0.77 (standard error), respectively (P = 0.033), whereas heterozygous cells (AV) displayed intermediate values. This difference was likely due to the higher basal H2O2 production of AA-WBCs compared to that of other genotypes. These results suggest that the Ala16Val-MnSOD polymorphism has toxicogenetic effects in human cells exposed to MeHg.

Association between Machado-Joseph disease and oxidative stress biomarkers

Spinocerebellar ataxia type 3, also called Machado-Joseph disease (MJD), is an hereditary autosomal dominant neurodegenerative disease that affects the cerebellum and its afferent and efferent connections. Since the mechanism by which mutant ataxin-3 eventually leads to neuronal death is poorly understood, additional investigations to clarify the biological alterations related to Machado-Joseph disease are necessary. Recent investigations suggest that oxidative stress may contribute significantly to Machado-Joseph disease. We compared markers of oxidative stress between Machado-Joseph disease and healthy control subjects. The results showed that Machado-Joseph patients have higher catalase levels and lower thiol protein levels compared to control subjects. The peripheral blood lymphocyes of MJD patients also showed higher levels of DNA damage by the comet assay than control subjects. Our results corroborate the hypothesis that the oxidative stress is associated with MJD patients. However, whether strategies to increase cellular antioxidative capacity may be effective therapies for the treatment of Machado-Joseph disease is an open question.

Inflammatory cytokines in vitro production are associated with Ala16Val superoxide dismutase gene polymorphism of peripheral blood mononuclear cells

Obesity is considered a chronic low-grade inflammatory state associated with a chronic oxidative stress caused by superoxide production (O(2)(-)). The superoxide dismutase manganese dependent (SOD2) catalyzes O(2)(-) in H(2)O(2) into mitochondria and is encoded by a single gene that presents a common polymorphism that results in the replacement of alanine (A) with a valine (V) in the 16 codon. This polymorphism has been implicated in a decreased efficiency of SOD2 transport into targeted mitochondria in V allele carriers. Previous studies described an association between VV genotype and metabolic diseases, including obesity and diabetes. However, the causal mechanisms to explain this association need to be more elucidated. We postulated that the polymorphism could influence the inflammatory response. To test our hypothesis, we evaluated the in vitro cytokines production by human peripheral blood mononuclear cells (PBMCs) carrier's different Ala16Val-SOD2 genotypes (IL-1, IL-6, IL-10, TNF-α, IFN-γ). Additionally, we evaluated if the culture medium glucose, enriched insulin, could influence the cytokine production. Higher levels of proinflammatory cytokines were observed in VV-PBMCs when compared to AA-PBMCs. However, the culture medium glucose and enriched insulin did not affect cytokine production. The results suggest that Ala16Val-SOD2 gene polymorphism could trigger the PBMCs proinflammatory cytokines level. However, discerning if a similar mechanism occurs in fat cells is an open question.

Influence of Val16Ala SOD2 polymorphism on the in-vitro effect of clomiphene citrate in oxidative metabolism

This study investigated the in-vitro antioxidant properties of the ovulation induction drug, clomiphene citrate, and assessed whether its effects are influenced by the Val16Ala polymorphism in the SOD2 gene, which encodes manganese superoxide dismutase enzyme. The investigation involved an in-vitro experimental protocol testing the effect of different concentrations of clomiphene citrate on antioxidant capacity, reactive oxygen species (ROS) production and peripheral blood mononuclear cell (PBMC) culture viability. A total of 58 healthy adult women were genotyped for the Val16Ala SOD2 polymorphism, and blood samples were collected to perform in-vitro experiments. ROS production and cytotoxicity assays were performed on blood and PBMC from carriers of different Val16Ala SOD2 genotypes. Clomiphene citrate exhibited antioxidant capacity and effects and decreased ROS production. The AA genotype displayed a more responsive antioxidant effect with clomiphene citrate treatment than other genotypes. AA and AV PBMC showed an increase in viability following treatment with 10 μmol/l clomiphene citrate when compared with control groups. The results suggest that clomiphene citrate exhibits antioxidant activity similar to that observed with other selective oestrogen receptor modulators, and the intensity of the effect appears to be SOD2 polymorphism dependent. This study was performed to investigate whether clomiphene citrate, a drug broadly used to evaluate reproductive function in women, presents antioxidant effects and if these effects could be influenced by genetic variation in the women. We found evidence that clomiphene citrate has some antioxidant properties similar to those observed with other selective oestrogen receptor modulators such as tamoxifen. As the antioxidant enzyme manganese superoxide dismutase (SOD2) is considered a key molecule involved in female reproductive metabolism, we also tested if a functional SOD2 gene polymorphism (Val16Ala) could influence the in-vitro antioxidant clomiphene citrate response. Significant differences of the clomiphene citrate antioxidant effect on PBMC with different Val16Ala SOD genotypes were observed in this study. Based on these results, we could speculate that alterations in SOD2 activity caused by the Val16Ala polymorphism can result in differential responses to drugs such as clomiphene citrate. In assisted reproduction clinics, clomiphene citrate is commonly used to induce ovulation, especially in patients with polycystic ovary syndrome. However, some women have clomiphene citrate resistance and either ovulation is not triggered by the drug or ovulation is induced but the pregnancy still fails. The causes of no effect of clomiphene citrate remain unclear and we cannot discard the influence of genetic effects including the Val16Ala SOD2 polymorphism. Therefore, it is important to perform complementary investigations considering the potential pharmacogenetic influence of Val16Ala SOD2 polymorphism on the treatment of polycystic ovary syndrome or in ovulation to elucidate this question.

Lifestyle, health characteristics and alcohol abuse in young adults who are non-daily smokers

CONTEXT AND OBJECTIVES

Despite the decline in the prevalence of tobacco use in many countries, including Brazil, there are growing numbers of smokers who continue to smoke at a low daily rate, or less frequently (non-daily smokers). This group needs to be better characterized in order to direct preventive actions and public health policies. The aim here was to compare lifestyle, health characteristics and alcoholism problems among young adult smokers, non-daily smokers and non-smokers.

DESIGN AND SETTING

This was a cross-sectional study in which volunteers from the university community and its surrounds in Santa Maria, State of Rio Grande do Sul, Brazil, were included between October 2007 and January 2008.

METHODS

Out of 1240 volunteers initially contacted in a university cafeteria, a total of 728 participants of mean age 22.45 ± 3.32 years were selected for final analysis. Data were collected using structured questionnaires.

RESULTS

In general, it was observed that the non-daily smokers showed intermediate characteristics in relation to the smokers and non-smokers. However, there was a significant association between non-daily smoking and alcohol abuse. The non-daily smokers presented an odds ratio of 2.4 (95% confidence interval: 1.10-5.48) in relation to the daily smokers and an odds ratio of 3.3 (confidence interval: 1.7-6.5) in relation to the non-smokers, with regard to presenting a positive CAGE test, thereby indicating alcohol abuse or dependence.

CONCLUSION

The study suggested that non-daily smoking and alcohol consumption were concomitant behaviors.