Modulation of glutathione transferase P1-1 activity by retinoic acid in neuroblastoma cells

The effects of olibanum on male reproductive system damage in a lipopolysaccharide induced systemic inflammation model in rat

Background

Lipopolysaccharide (LPS) as a particle of Gram-negative bacteria is a main contributer in the pathogenesis of the male reproductive system infectious. Male infertility due to LPS is reported to be related to overproduction reactive oxygen species. This study aimed to investigate the effects of olibanum on oxidative stress and apoptosis in testes and sperm dysfunction induced by LPS.

Methods

The male (n = 28) rats were allocated in four groups: control, LPS (1 mg/kg, i.p., 14 days), LPS + Olibanum 100 (100 mg/kg, i.p., 14 days), and LPS + Olibanum 200 (200 mg/kg, i.p., 14 days). Germ cell apoptosis was determined by TUNEL assays and computed using the stereological method. Additionally, semen samples of the animals were analyzed for sperm count and morphology. Oxidative stress indicators were also determined.

Results

The count of TUNEL-positive germ cells in LPS-treated rats was more than that in the controls. Treatment of the animals with olibanum significantly attenuated the number of apoptotic cells compared to the LPS group. The sperm count and those with a normal morphology in LPS-treated rats was lower than that in the controls. Administration of olibanum significantly improved the sperms with normal morphology and sperm count. Olibanum treatment also improved superoxide dismutase, catalase, and total thiol in testicular tissue and decreased malondialdehyde.

Conclusion

Administering both doses of olibanum in LPS-treated rats had potentially a therapeutic value in reducing germ cell apoptosis, as well as improving sperm parameters.

Proteomic approach reveals novel targets for retinoic acid-mediated therapy of thyroid carcinoma

Our previous studies demonstrated that retinoic acid (RA)-induced reduction of both, the key glycolytic enzyme ENO1 and proliferation-promoting c-Myc, resulted in decreased vitality and invasiveness of the follicular thyroid carcinoma cell lines FTC-133 and FTC-238. By employing two-dimensional electrophoresis and mass spectrometry, we identified proteins affected by RA treatment. In addition to previously reported decrease in ENO1 expression, we found that RA led to significantly reduced levels of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase isoenzymes M1/M2 (PKM1/M2), peptidyl-prolyl cis-trans isomerase A (PPIA), transketolase (TKT), annexin A2 (ANXA2), glutathione S-transferase P (GSTP1) and peroxiredoxin 2 (PRDX2) as compared to untreated control. The same proteins investigated on thyroid tissues were found to be significantly up-regulated in follicular, papillary and undifferentiated thyroid carcinomas when compared with goiter and adenoma tissues. These findings identify new target proteins for RA-mediated anti-tumor and re-differentiation therapies and provide novel insights into treatments for thyroid carcinoma.

Bacterial lipopolysaccharide-induced oxidative stress in adult rat Sertoli cells in vitro

Inflammatory reactions that result from microbial infections, both localized and systemic, are reported to cause transient or permanent male infertility. The cellular mechanisms underlying the inhibitory effect of microbial infection on spermatogenesis is not fully understood. However, there is evidence that spermatogenesis is affected by bacterial lipopolysaccharides (LPS) that induce acute inflammatory responses. The aim here was to use LPS treatments to investigate the potential oxidative stress and toxicity in primary cultures of adult rat Sertoli cells. The Sertoli cells were established and incubated with different concentrations of LPS (5, 10 or 20 microg/ml) for 6, 12 and 24h. Lipid peroxidation (LPO) and hydrogen peroxide (H(2)O(2)) production, along with superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), glutathione reductase (GR), reduced glutathione (GSH), lactate, lactic acid dehydrogenase (LDH), gamma-glutamyl transpeptidase (gamma-GT) and beta-glucuronidase were measured in these cells. LPO as well as H(2)O(2) production were significantly increased while antioxidant enzyme activities and GSH concentration were significantly depressed. Effects were dose and time-dependent at all incubation periods with 10 and 20 microg/ml LPS. Moreover, markers of Sertoli cell function such as lactate production, LDH, gamma-GT and beta-glucuronidase activities were decreased in a time and dose-dependent manner. Incubation of Sertoli cells with 5 microg/ml LPS for 12 and 24h significantly increased oxidative status but significantly decreased the antioxidant enzyme activities, GSH concentration and Sertoli cell markers. In contrast, the oxidative and antioxidant status and markers of Sertoli cell function did not show any significant change in treated Sertoli cells with 5 microg/ml LPS for 6h. Therefore, it may be concluded that LPS induces oxidative stress in Sertoli cells and adversely affects Sertoli cell functions.

Bacterial lipopolysaccharide-induced oxidative stress in the impairment of steroidogenesis and spermatogenesis in rats

Microbial infections, localized as well as systemic, are known to cause transitive or permanent male infertility. However, the mechanisms of infection-induced infertility are largely unknown. Earlier reports showed that steroidogenesis and spermatogenesis are affected during bacterial lipopolysaccharide (LPS)-induced acute inflammation. The present study used an LPS rat model to investigate the role of oxidative stress in spermatogenesis. Intraperitoneal administration of bacterial LPS (5mg/kg body weight) to adult male albino rats elevated testicular malondialdehyde (MDA) and 4-hydroxy-2-nonenal (HNE), and decreased the activities of testicular antioxidant enzymes such as catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase. The GSH/GSSG ratio also decreased significantly. Time series analysis revealed transitory oxidative stress and expression of inflammatory mediators such as interleukin-1beta (IL-1beta), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) from 3h to 12h after LPS. Testicular expression of steroidogenic acute regulatory (StAR) protein decreased to 24h, in correlation with damage to spermatogenesis. These data are consistent with oxidative stress as a major causal factor in altered steroidogenesis, spermatogenesis, and perhaps male infertility during endotoxin-induced acute inflammation.

Single nucleotide polymorphism of pi-class glutathione s-transferase and susceptibility to endometrial carcinoma

PURPOSE

Endometrial carcinoma is the most common gynecologic cancer in developed countries. Prolonged unopposed estrogen exposure has been identified as the major risk factor. The pi-class glutathione S-transferase (GSTP1) is a phase II metabolic enzyme that is important in the detoxification of a wide range of electrophiles including carcinogenic steroid-hormone intermediates generated through oxidative metabolism. In this study, we aimed at determining the association between the GSTP1 polymorphism and the risk of endometrial carcinoma in a Chinese population.

EXPERIMENTAL DESIGN

Genotyping of 180 cases and 200 age-matched controls were assessed by PCR-RFLP approach and confirmed by direct sequencing.

RESULTS

Statistical analysis showed that patients of valine allele carriers had 2.03-fold of increased risk of developing endometrial carcinoma (P < 0.01). The allele frequencies for the Ile and Val variants between the cancer cases and controls were also significantly different (P < 0.01; odds ratio, 1.59; 95% confidence interval, 1.13-2.23). Such association was shown in endometrial cancers as a group and in type I endometrioid adenocarcinoma but not the type II nonendometrioid adenocarcinoma. In addition, the Val allele was found significantly associated with high-grade endometrial cancer and/or endometrial cancer of deep myometrial invasion (P < 0.01). Interestingly, the relatively low frequency of Val/Val genotype in both the cancer cases and controls, in parallel with the lower incidence of endometrial cancer in Chinese, was observed when compared with those in Caucasians.

CONCLUSIONS

Our findings suggested that the GSTP1 Ile(105)Val polymorphism was associated with an increased risk of endometrial cancer. Further studies may be required to explore the possible significance of these polymorphisms on GSTP1-related metabolism that may affect the susceptibility of Asians to endometrial carcinoma.

Phorbol ester responsiveness of the glutathione S-transferase P1 gene promoter involves an inducible c-jun binding in human K562 leukemia cells

Overexpression of the glutathione S-transferase P1 (GSTP1) gene is related to drug resistance in human cancer cells. However, the mechanisms of the transcriptional activation of this gene remain unclear. In this study, we examined the molecular mechanisms underlying phorbol ester mediated gene regulation using human K562 leukemia cells as a model. Promoter deletion analyses revealed that the activator protein-1 (AP-1) transcription factor site was crucial for 12-O-tetradecanoyl phorbol 13-acetate (TPA)-mediated GSTP1 gene transcription. Electrophoretic mobility shift assays and transient transfection analysis demonstrated that both DNA binding and transactivation activities of AP-1 were induced by TPA. By supershift analysis, we identified transcription factors c-jun and fra-1 as well as NF-E2p45 as components of the induced binding complex. These results show for the first time that the phorbol ester TPA is involved in the molecular mechanism(s) mediating the activation of the GSTP1 promoter in a human leukemia model.

Role of glutathione S-transferases in oxidative stress-induced male germ cell apoptosis

Cellular apoptosis in a tissue may occur for the maintenance of proper ratio of cells or because of toxic effects of free radicals or other agents. Male germ cell apoptosis is pivotal in maintaining the proper functioning of the testis, but it is not clear how free radicals affect germ cells and what the defense mechanisms are that are used by these cells to combat the toxic effects of the products of oxidative stress. This study shows that male germ cells are susceptible to H(2)O(2)-induced stress and, upon exposure to H(2)O(2) in vitro, demonstrate a typical apoptotic phenotype that includes DNA fragmentation and formation of DNA ladders. Other changes include considerable accumulation of products of lipid peroxidation in the germ cells after exposure to H(2)O(2). Evidence is presented for the existence of multiple isoforms of glutathione S-transferases (GSTs) that possess both transferase and Se-independent peroxidase activity. Germ cell GST activity increases after H(2)O(2) exposure. If this increase in activity is inhibited with suitable inhibitors, the formation of products of lipid peroxidation is augmented, resulting in germ cell apoptosis. Also, when constitutive GST activity is inhibited, accumulation of products of lipid peroxidation occurs, resulting in increased cellular apoptosis. These data show that GSTs form a part of adaptive response of germ cells to oxidative stress and are important constituents in detoxifying the products of lipid peroxidation.