R-sulforaphane modulates the expression profile of AhR, ERα, Nrf2, NQO1, and GSTP in human breast cell lines.

Our previous study showed remarkable differences in the effect of R-sulforaphane (R-SFN) on the expression of CYPs 19, 1A1, 1A2, and 1B1 in ER(+) MCF7, ER( -) MDA-MB-231, and non-tumorigenic immortalized MCF10A (8). This study aimed to evaluate the effect of R-SFN on phase II enzymes induction and expression of AhR, Nrf2, and ERα in the same breast cell lines. The results showed increased expression of GSTP as a result of treatment with R-SFN in breast cancer cells. An increased NQO1 transcript and protein levels were found in all breast cells, with the most significant increase in MCF7 cells. Similarly, the enhancement of Nrf2 expression was noticed in all tested cells. AhR gene transcript and protein were decreased in MCF7 cells. In MDA-MB-231, increased AhR mRNA was not confirmed at the protein level. No differences were found in the expression of ERα. Overall, the results of the present study extended our earlier suggestions on the possible interference of R-SFN with estrogens homeostasis in breast cancer cells differing in ERα status, as well as in non-tumorigenic immortalized breast epithelial cells. While some of R-SFN effects might be beneficial and useful in breast cancer prevention, the others, particularly GSTP induction, may lead to adverse effects.

Glutathione S-transferases P1-mediated interleukin-6 in tumor-associated macrophages augments drug-resistance in MCF-7 breast cancer.

Glutathione S-transferase P1 (GSTP1), a phase II detoxifying enzyme, is overexpressed and plays an important role during breast cancer drug resistance. Tumor-associated macrophages (TAMs), representing most of the leukocyte population in solid tumors, are involved in cancer cell resistance to chemotherapy. Although GSTP1 exists in TAMs, whether GSTP1 in TAMs promotes drug resistance is still unclear. In the current study, we found a novel mechanism that GSTP1 in TAMs contributes breast cancer cell drug resistance. GSTP1 is aberrantly expressed in TAMs from breast cancer tissues of patients after chemotherapy than that without chemotherapy. Adriamycin (ADR) time-dependently induced the expression of GSTP1 in TAMs in vitro. Conditional medium of TAMs significantly inhibited ADR-induced cell death of MCF-7 breast cancer cells. Meanwhile, overexpression of GSTP1 in TAMs promoted the expression and release of interleukin-6 (IL-6) associated with reduced ADR-induced breast cell death, which was reversed by IL-6 antibody. Mechanistically, GSTP1 interacted with inhibitor of nuclear factor κB kinase ß (IKKß) to activate nuclear factor-κB (NF-κB) to induced the expression and release of IL-6 in TAMs. Moreover, IL-6 further upregulated GSTP1 through c-Jun, and ultimately mediated drug resistance in MCF-7 cells. Taken together, our data demonstrated for the first time that GSTP1 in TAMs promoted ADR-resistance in breast cancer by regulating interleukin-6 release.

Targeting G6PD reverses paclitaxel resistance in ovarian cancer by suppressing GSTP1.

Ovarian cancer is one of the leading causes of mortality in women worldwide. Currently, paclitaxel is one of the most effective chemotherapies. However, resistance to paclitaxel is a major cause of therapy failure and the precise mechanism of paclitaxel resistance remains unclear. In this study, we demonstrated that the oxidative pentose phosphate pathway (PPP) enzyme glucose-6-phosphate dehydrogenase (G6PD) promotes paclitaxel resistance. We showed that G6PD expression was higher in paclitaxel-resistant cancer cells than in their paclitaxel-sensitive counterparts. Furthermore, we demonstrated that suppressing G6PD using shRNA, or an inhibitor, either as single agents or in combination, sensitized paclitaxel-resistant cancer cells to paclitaxel treatment and thereby improving the therapeutic efficacy of paclitaxel. Interestingly, we found that the upregulation of G6PD in paclitaxel-resistant cells was due to the decreased expression of protein arginine methyltransferase 6 (PRMT6), which targets the promoter of G6PD. We further identified that G6PD promotes paclitaxel resistance by regulating the expression of glutathione S-transferase P1 (GSTP1), which confers resistance to chemotherapy by detoxifying several anticancer drugs. Taken together, our results suggest that G6PD is a novel potential target to overcome paclitaxel resistance.

GSTP1 Inhibits LPS-Induced Inflammatory Response Through Regulating Autophagy in THP-1 Cells.

Glutathione S-transferase Pi (GSTP1) was originally identified as one of the cytosolic phase II detoxification enzymes and was also considered to function via its non-catalytic, ligand-binding activity. Autophagy is a self-protective mechanism of the cell to remove unnecessary or dysfunctional components, which plays a crucial role in balancing the beneficial and detrimental effects of immunity and inflammation. However, little is known about whether and how GSTP1 mediates autophagy via inhibiting LPS-induced inflammatory response. Here, we show that LPS-induced autophagy and autophagic flux blockade in THP-1 cells in a concentration- and time-dependent manner. Further, we found that the autophagy activation inhibited the activation of inflammatory signaling pathway and the release of inflammatory factors. However, inhibition of autophagy by 3-methyladenine or chloroquine significantly reduced the anti-inflammatory effect of GSTP1. In addition, our findings provide evidence that GSTP1 regulates autophagy through PI3K-Akt-mTOR pathway and inhibits LPS-induced inflammation. Overall, the current study provides an important reference for future applications of GSTP1 in the treatment of inflammatory diseases.

Combined Detection of HER2, Ki67, and GSTP1 Genes on the Diagnosis and Prognosis of Breast Cancer.

OBJECTIVE: Breast cancer (BC) is a common malignant tumor in females. The combined assay of multiple molecular markers benefits the diagnosis and prognostic prediction. Human epidermal growth factor receptor 2 (HER2) facilitates the proliferation and differentiation of cancer cells through ligand binding. Ki67 is a tumor proliferation-related gene, whereas GSTP1 is a DNA repair-related gene. This study thus investigated the significance of HER2 and Ki67/GSTP1 gene combined assay in the diagnosis and prognosis of BC. MATERIALS AND METHODS: A total of 86 breast tumor tissues and adjacent tissues were collected. Gene expression and protein levels of HER2 and Ki67 were quantified by real-time polymerase chain reaction (PCR) and Western blot, respectively. Methylation frequency of GSTP1 was analyzed by methylation-specific PCR. The correlation between HER2 and Ki67/GSTP1 and clinical/pathological features of BC was analyzed. RESULTS: Gene and protein expression levels of HER2 and Ki67 in tumor tissues were increased (p < 0.05 compared with adjacent tissues). Methylation frequency of GSTP1 gene was 37.2%, which was significantly higher in breast tumor tissues than in adjacent tissues (12.79%, p < 0.05). HER2 expression was positively correlated with TNM stage, tumor size, and lymph node metastasis, and negatively correlated with tissue grade and estrogen receptor (ER)/progesterone receptor (PR) expression (p < 0.05). GSTP1 methylation was positively correlated with TNM stage and tumor size, and negatively correlated with ER/PR expression (p < 0.05). CONCLUSIONS: HER2, Ki67, and GSTP1 methylation were correlated with clinical and pathological features of BC. The combined assay benefits the early diagnosis and prognostic prediction of cancer.

Small hepatitis delta antigen selectively binds to target mRNA in hepatic cells: a potential mechanism by which hepatitis D virus downregulates glutathione S-transferase P1 and induces liver injury and hepatocarcinogenesis.

Liver coinfection by hepatitis B virus (HBV) and hepatitis D virus (HDV) can result in a severe form of hepatocellular carcinoma with poor prognosis. Coinfection with HDV and HBV causes more deleterious effects than infection with HBV alone. Clinical research has shown that glutathione S-transferase P1 (GSTP1), a tumor suppressor gene, is typically downregulated in liver samples from hepatitis-infected patients. In the present study, our data indicated that small HDV antigen (s-HDAg) could specifically bind to GSTP1 mRNA and significantly downregulate GSTP1 protein expression. For the human fetal hepatocyte cell line L-02, cells transfected with s-HDAg, along with decreased GSTP1 expression, there was a significant accumulation of reactive oxygen species (ROS) and increased apoptotic ratios. Restoring GSTP1 expression through silencing s-HDAg via RNAi or overexpressing exogenous GSTP1 could largely recover the abnormal cell status. Our results revealed a novel potential mechanism of HDV-induced liver injury and hepatocarcinogenesis: s-HDAg can inhibit GSTP1 expression by directly binding to GSTP1 mRNA, which leads to accumulation of cellular ROS, resulting in high cellular apoptotic ratios and increased selective pressure for malignant transformation. To our knowledge, this is the first study to examine s-HDAg-specific pathogenic mechanisms through potential protein-RNA interactions.

Evaluation of glutathione S-transferase pi 1 expression and gene promoter methylation in Moroccan patients with urothelial bladder cancer.

BACKGROUND: Glutathione S-transferase pi 1 (GSTP1) is a cytosolic detoxifying enzyme that protects cells against deleterious effects of oxidative stress. Deregulated expression of GSTP1 protein and aberrant promoter methylation of GSTP1 gene were reported in various human tumors and were shown to be involved in the molecular pathway for cancer development. AIMS AND METHODS: In this study, we aimed to determine the expression status of GSTP1 in relation to its gene promoter methylation in Moroccan population of 30 bladder cancer (BC) patients and in two noncancerous bladder tissues used as controls. GSTP1 expression was assessed by immunohistochemistry and GSTP1 gene promoter methylation status was studied by methylation-specific PCR (MS-PCR). RESULTS: Glutathione S-transferase pi 1 was expressed in the two normal tissues. In BC cases, GSTP1 expression was strong in 23.33% (7/30), moderate in 60% (18/30), and weak in 13.33% (4/30) of cases, while GSTP1 was not expressed in one cancer case (3.33%). Variability of GSTP1 expression does not correlate with high-grade cancer or invasive-stage (p > 0.05). No GSTP1 gene promoter methylation was detected in all control and cancer cases. CONCLUSION: Our data suggest that GSTP1 expression is not associated with BC development, limiting its use as a biomarker for BC management in Morocco. Moreover, difference in GSTP1 expression among BC cases is not due to GSTP1 promoter methylation.

Strong carcinogenic stress response induction of preneoplastic cells positive for GST-P in the rat liver: Physiological mechanism for initiation.

AIMS: To identify experimental conditions that induce preneoplastic cells positive for glutathione S-transferase P-form (GST-P) in the rat liver by new approaches, and analysis of the mechanism of cancer initiation based on the findings. MAIN METHODS: The experimental protocols employed to induce GST-P+ preneoplastic cells in rat liver were as follows. Protocol 1: adult rats were fed basal diet containing 2-acetylaminofluorene (AAF, 0.02% by wt) and high concentrations of N-acetyl-l-cysteine (0.5%) over 10 weeks. Protocol 2: rats were subjected to partial hepatectomy (2/3PH), followed by an AAF (0.04%) diet for two more weeks. Vibratome-prepared liver sections were then immunostained for GST-P. KEY FINDINGS: GST-P was inducible in the rat liver in response to the strong carcinogenic stress by AAF in the two experimental protocols. When examined immunocytochemically with vibratome sections, the biliary tracts of hepatocytes, GST-P+ single hepatocytes and foci were heavily positive for the marker enzyme in addition to ordinary cytosolic staining of preneoplastic cell populations. The biliary tracts of hepatocytes were severely injured, and the excretory portions of GST-P+ single hepatocytes were significantly injured. SIGNIFICANCE: The cytotoxic action of AAF that give rise to the GST-P+ single hepatocytes was suggested to be an injury to the excretory pump(s) and the duct of hepatocytes. A new physiological mechanism was hypothesized for the induction of preneoplastic cell populations in the rat liver instead of a genetic mechanism.

Exenatide Increases IL-1RA Concentration and Induces Nrf-2‒Keap-1‒Regulated Antioxidant Enzymes: Relevance to ß-Cell Function.

Purpose: We previously demonstrated the anti-inflammatory and antioxidant effects of exenatide. We now hypothesized that exenatide also increases the plasma concentration of interleukin-1 receptor antagonist (IL-1RA), an endogenous anti-inflammatory protein, and modulates the nuclear factor erythroid 2‒related factor‒Kelchlike ECH-associated protein 1‒antioxidant response element (Nrf-2‒Keap-1‒ARE) system to induce key antioxidant enzymes to suppress inflammatory and oxidative stress. Methods: Twenty-four patients with obesity and type 2 diabetes receiving combined oral and insulin therapy were randomly assigned to receive either exenatide 10 µg or placebo twice a day for 12 weeks. Results: Exenatide increased IL-1RA concentration by 61% (from 318 ± 53 to 456 ± 88 pg/mL; P < 0.05). Exenatide treatment also suppressed Keap-1 protein (P < 0.05) and increased messenger RNA expression of NQO-1, glutathione S-transferase PI, heme oxygenase-1, and p21 and increased NAD(P)H dehydrogenase [quinone] 1 protein (P < 0.05) in mononuclear cells. Conclusions: Because IL-1RA protects, maintains, and stimulates ß-cell function in humans and Nrf-2‒Keap-1‒ARE protects ß cells in animals with experimental diabetes, these actions of exenatide may contribute to a potential protective effect on ß cells in diabetes.

Troxerutin with copper generates oxidative stress in cancer cells: Its possible chemotherapeutic mechanism against hepatocellular carcinoma.

Troxerutin (TXER) a rutin derivative is known for its anticancer effect against hepatocellular carcinoma (HCC). As part of large study, recently we have shown TXER interact with genetic material and its anti-mutagenic property. In the present study we have explored its possible mode of action in HCC. Since TXER alone did not show significant anticancer effect on Huh-7 cells, in vitro biochemical assays were performed for determining anticancer efficacy of TXER + metal complex using transition metals such as Cu, Zn, and Fe. The anticancer efficacy of TXER + Cu on Huh-7 cells were evaluated using MTT assay, DCFDA, JC-1 staining, comet assay, cell cycle analysis, immunocytochemistry, and Western blotting. Non-toxic nature of TXER was analyzed on primary rat hepatocytes. The in vivo efficacy of TXER was tested in N-nitrosodiethylamine initiated and γ-benzene hexachloride and partial hepatectomy promoted rat liver cancer. Liver markers, transition metal levels, histopathological examination, and expression levels of GST-P, 8-OHdG and Ki-67 were studied to assess the in vivo anticancer effect of TXER. We observed that TXER + Cu induced extensive cellular death on Huh-7 cells through generating free radicals and did not possess any toxic effect on normal hepatocytes. The in vivo studies revealed that TXER possess significant anti-cancer effect as assessed through improved liver markers and suppressed GST-P, 8-OHdG, and Ki-67 expression. TXER treatment reduced the hepatic Cu level in cancer bearing animals. Current study brings the putative mechanism involved in anti-cancer effect of TXER, further it will help to formulate phytoconstituents coupled anti-cancer drug for effective treatment of HCC.

Identification and characterization of the zebrafish glutathione S-transferase Pi-1.

Zebrafish has in recent years emerged as a popular vertebrate model for use in pharmacological and toxicological studies. While there have been sporadic studies on the zebrafish glutathione S-transferases (GSTs), the zebrafish GST gene superfamily still awaits to be fully elucidated. We report here the identification of 15 zebrafish cytosolic GST genes in NCBI GenBank database and the expression, purification, and enzymatic characterization of the zebrafish cytosolic GST Pi-1 (GSTP1). The cDNA encoding the zebrafish GSTP1 was cloned from a 3-month-old female zebrafish, expressed in Eschelichia coli host cells, and purified. Purified GSTP1 displayed glutathione-conjugating activity toward 1-chloro-2,4-dinitrobenzene as a representative substrate. The enzymatic characteristics of the zebrafish GSTP1, including pH-dependency, effects of metal cations, and kinetic parameters, were studied. Moreover, the expression of zebrafish GSTP1 at different developmental stages during embryogenesis, throughout larval development, onto maturity was examined.

Aberrant Epigenetic Alterations of Glutathione-S-Transferase P1 in Age-Related Nuclear Cataract.

PURPOSE: Oxidative damage of lens tissue contributes to the formation of age-related cataract. Pi-class glutathione-S-transferase (GSTP1) plays a role in the removal of oxidative adducts by transferring them to glutathione. To assess epigenetic regulation of GSTP1 and its potential role in age-related nuclear cataract (ARNC) pathogenesis, we evaluated GSTP1 mRNA expression, methylation, and chromatin modifications in lenses from ARNC patients. METHODS: The mRNA and protein of lens GSTP1 were assayed by relative quantitative real-time polymerase chain reaction (qRT-PCR) and Western blots. Methylation of the GSTP1 promoter was determined by bisulfite genomic sequencing. Chromatin modification was detected by chromatin immunoprecipitation. DNA methyltransferase (DNMT) and histone deacetylase (HDAC) activities were also assayed by enzyme-linked immunosorbent assay (ELISA)-like reaction. To assess the effect of DNA methylation on the mRNA expression of GSTP1, human lens epithelium HLE-B3 cells were treated with the demethylation compound 5-aza-dC, followed by qRT-PCR assay. RESULTS: GSTP1 mRNA and protein levels were significantly reduced in lens epithelium and cortex of ARNC cases versus age-matched controls. The changes corresponded to hypermethylation of the GSTP1 promoter CpG islands. The loss of GSTP1 mRNA and protein and the increased DNA promoter methylation might be correlated with the severity of the ARNC. ARNC lenses also had lower acetylation of histone proteins H3, H4, and lower methylation of H3K4, and higher methylation of H3K9. Histone modifications were not correlated with the severity of the ARNCs. DNMT and HDAC were elevated in lenses from ARNCs compared with controls. Demethylation treatment of HLE-B3 cells with 5-aza-dC enhanced the expression of GSTP1. CONCLUSIONS: Epigenetic alteration of GSTP1 regulates its expression in lens epithelial and cortical tissues. These changes likely contribute to the pathogenesis of ARNC.

Effects of Ginger Phenylpropanoids and Quercetin on Nrf2-ARE Pathway in Human BJ Fibroblasts and HaCaT Keratinocytes.

Quercetin and phenylpropanoids are well known chemoprotective compounds identified in many plants. This study was aimed at determining their effects on activation of Nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant response element (Nrf2-ARE) signalling pathway and expression of its important downstream effector phase II detoxification enzyme glutathione-S-transferase P1 (GSTP1) in BJ foreskin fibroblasts and skin HaCaT keratinocytes. Cell lines and their corresponding Nrf2-ARE luciferase reporter cells were treated by ginger phenylpropanoids and quercetin for 10 h and the level of Nrf2 activity was subsequently determined. Both, ginger phenylpropanoids and quercetin, significantly increased the level of Nrf2 activity. Subsequent western blot analyses of proteins showed the increased expression level of glutathione-S-transferase P1 (GSTP1) in BJ cells but not in HaCaT cells. Such phenomenon of unresponsive downstream target expression in HaCaT cells was consistent with previous studies showing a constitutive expression of their GSTP1. Thus, while both ginger phenylpropanoids and quercetin have the property of increasing the level of Nrf2 both in HaCaT and in BJ cells, their effects on its downstream signalling were mediated only in BJ cells.

Glutathione S-transferase pi expression regulates the Nrf2-dependent response to hormetic diselenides.

Glutathione S-transferase pi (GSTP), a phase II gene downstream of the nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant-responsive element (ARE)/electrophile response element (EpRE) transcription pathway, plays a key role in both the signaling and detoxification response to Se-organic compounds with thiol peroxidase activity. We here investigated the role of GSTP on the Nrf2 activation response of cells challenged with a new class of diselenides derived from the basic structure of diphenyl diselenide [(PhSe)2]. These diselenides, and particularly 2,2'-diselenyl dibenzoic acid (DSBA), behave as mild thiol peroxidases leading to a moderate generation of H2O2 and NOx, and signaling of stress-activated and survival-promoting MAPKs, which ultimately control the mitochondrial pathway of apoptosis. Used in murine embryonic fibroblasts (MEFs) and HepG2 human hepatocarcinoma cells to produce submaximal conditions of stress, the diselenide compounds stimulated Nrf2 nuclear translocation and then the transcription of the same Nrf2 gene as well as of GSTP and other phase II genes. This resulted in a higher degree of protection against H2O2 cytotoxicity (hormetic effect). Diselenide toxicity increased in GSTP knockout MEFs by a higher generation of NOx and stress activated protein kinase (SAPK)/JNK activation. A lowered hormetic potential of these cells was observed in association with an abnormal expression and nuclear translocation of Nrf2 protein. Immunoprecipitation and affinity purification experiments revealed the existence of an Nrf2/GSTP complex in MEFs and HepG2 cells. Covalent oligomers of GSTP subunits were observed in DSBA-treated HepG2 cells. In conclusion, GSTP gene expression influences the Nrf2-dependent response to hormetic diselenides. Mechanistic interpretation for this GSTP-dependent effect may include a direct and redox-sensitive interaction of GSTP with Nrf2 protein.

Identification of proteins responsible for adriamycin resistance in breast cancer cells using proteomics analysis.

Chemoresistance is a poor prognostic factor in breast cancer and is a major obstacle to the successful treatment of patients receiving chemotherapy. However, the precise mechanism of resistance remains unclear. In this study, a pair of breast cancer cell lines, MCF-7 and its adriamycin-resistant counterpart MCF-7/ADR was used to examine resistance-dependent cellular responses and to identify potential therapeutic targets. We applied nanoflow liquid chromatography (nLC) and tandem mass tags (TmT) quantitative mass spectrometry to distinguish the differentially expressed proteins (DEPs) between the two cell lines. Bioinformatics analyses were used to identify functionally active proteins and networks. 80 DEPs were identified with either up- or down-regulation. Basing on the human protein-protein interactions (PPI), we have retrieved the associated functional interaction networks for the DEPs and analyzed the biological functions. Six different signaling pathways and most of the DEPs strongly linked to chemoresistance, invasion, metastasis development, proliferation, and apoptosis. The identified proteins in biological networks served to resistant drug and to select critical candidates for validation analyses by western blot. The glucose-6-phosphate dehydrogenase (G6PD), gamma-glutamyl cyclotransferase (GGCT), isocitrate dehydrogenase 1 (NADP+,soluble)(IDH1), isocitrate dehydrogenase 2 (NADP+,mitochondrial) (IDH2) and glutathione S-transferase pi 1(GSTP1), five of the critical components of GSH pathway, contribute to chemoresistance.

Correlation between the expression of DNMT1, and GSTP1 and APC, and the methylation status of GSTP1 and APC in association with their clinical significance in prostate cancer.

The aim of the present study was to investigate the correlation between the expression of DNA (cytosine­5)­methyltransferase 1 (DNMT1), glutathione S­transferase­P1 (GSTP1) and adenomatous polyposis coli (APC), and the methylation status of GSTP1 and APC in prostate cancer (PCa) and benign prostatic hyperplasia (BPH), and to examine its clinical significance. Immunohistochemistry and reverse transcription­polymerase chain reaction (RT­PCR) was used to detect the expression of DNMT1, GSTP1 and APC in 56 samples of PCa tissue and 10 samples of BPH tissue. Methylation­specific­PCR was used to detect the methylation status of the CpG island promoters of GSTP1 and APC. The positive rate of expression of DNMT1 in poorly­differentiated PCa, moderately­differentiated PCa, well­differentiated PCa and BPH was 86.7%, 70.6%, 55.6% and 30.0%, respectively (P<0.05); for GSTP1, the positive rate was 13.3%, 29.4%, 44.4% and 90.0%, respectively (P<0.05); and for APC, the positive rate was 23.3%, 47.6%, 55.6% and 70.0%, respectively (P<0.05). The correlation coefficient for the association between the expression of DNMT1 and GSTP1 was ­0.891 (P<0.05). Between the expression of DNMT1 and APC, the correlation coefficient was ­0.721 (P<0.05). GSTP1 and APC were hypermethylated in the majority of PCa tissue samples. The positive rate of methylation of these genes in poorly­differentiated PCa was 83.3% and 73.3%, respectively. By contrast, hypomethylation (or demethylation) was observed in BPH samples, in which the positive rate of methylation was 10.0% and 20.0%, respectively (P<0.05). The increased expression of DNMT1, and the reduced expression of GSTP1 and APC have an important role in the development of PCa. Due to the high expression of DNMT1 mRNA, it is likely that the hypermethylation of CpG islands contributed to the silencing of GSTP1 and APC in PCa tissues.

Inhibition of Forkhead box protein M1 by thiostrepton increases chemosensitivity to doxorubicin in T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive type of blood malignancy, deriving from T-cell progenitors in the thymus, and comprises 10-15% of pediatric and 25% of adult primary ALL cases. Despite advances, 20% of pediatric and the majority of adult patients with T-ALL succumb to mortality from resistant or relapsed disease, and the survival rate for patients with resistant or relapsed T-ALL remains poor. Alterations in the expression of Forkhead box protein M1 (FoxM1) have been detected in several types of cancer, and the inhibition of FoxM1 has been investigated as therapeutic strategy in cancer. The present study investigated the effects of the inhibition of FoxM1 by thiostrepton in human T-ALL Jurkat cells. The cells were treated with different concentrations of thiostrepton, either alone or in combination with doxorubicin. Cell viability was measured using CCK-8 assays and the cell cycle distribution, apoptosis and cell-associated mean fluorescence intensity of intracellular doxorubicin were assessed using flow cytometric analysis. The mRNA and protein expression levels were detected by reverse transcription-quantitative polymerase chain reaction and western blot analyses. The inhibition of FoxM1 by thiostrepton significantly decreased the proliferation of the Jurkat cells proliferation in a time- and dose-dependent manner. Cell arrest at the G2/M phase, and apoptosis was significantly increased in the thiostrepton-treated Jurkat cells. Thiostrepton reduced the half maximal inhibitory concentration of doxorubicin in the Jurkat cells, and significantly enhanced the cytotoxicity of doxorubicin within the Jurkat cells by enhancing doxorubicin-induced apoptosis and increasing the accumulation of intracellular doxorubicin. Furthermore, the inhibition of FoxM1 by thiostrepton enhanced doxorubicin-induced apoptosis, possibly through a caspase-3-dependent pathway, and increased the accumulation of intracellular doxorubicin, possibly through downregulating the expression of glutathione S-transferase pi. Collectively, the results of the present study suggested that targeting FoxM1 with thiostrepton resulted in potent antileukemia activity and chemosensitizing effects in human T-ALL Jurkat cells.

Induction of Pi form of glutathione S-transferase by carnosic acid is mediated through PI3K/Akt/NF-κB pathway and protects against neurotoxicity.

Carnosic acid (CA), a diterpene found in the rosemary (Rosmarinus officinalis), has been reported to have a neuroprotective effect. Glutathione S-transferase (GST) P (GSTP) is a phase II detoxifying enzyme that provides a neuroprotective effect. The aim of this study was to explore whether the neuroprotective effect of CA is via an upregulation of GSTP expression and the possible signaling pathways involved. SH-SY5Y cells were pretreated with 1 µM CA followed by treatment with 100 µM 6-hydroxydopamine (6-OHDA). Both immunoblotting and enzyme activity results show that CA also induced protein expression and enzyme activity of GSTP. Moreover, CA significantly increased the phosphorylation of phosphatidylinositol 3-kinase (PI3K)/Akt, the nuclear translocation of p65, but not mitogen-activated protein kinases (p < 0.05). Pretreatment with LY294002 (a PI3K/Akt inhibitor) suppressed the CA-induced phosphorylation of IκB kinase (IKK) and IκBα, p65 nuclear translocation, and nuclear factor-kappa B (NF-κB)-DNA binding activity as well as GSTP protein expression. Furthermore, CA attenuated 6-OHDA-induced caspase 3 activation, and cell death was reversed by GSTP siRNA or LY294002 treatment. Additionally, male Wistar rats with lesions induced by 6-OHDA treatment in the right striatum responded to treatment with CA, which significantly reversed the reduction in GSTP protein expression that resulted from lesioning. We suggest that CA prevents 6-OHDA-induced apoptosis through an increase in GSTP expression via activation of the PI3K/Akt/NF-κB pathway. Therefore, CA may be a promising candidate for use in the prevention of Parkinson's disease.

Ontogeny of the major xenobiotic-metabolizing enzymes expression and the dietary lipids modulatory effect in the rat dimethylbenz(a)anthracene-induced breast cancer model.

Breast cancer is the most common malignancy in women worldwide. Environmental factors such as xenobiotic exposure and lifestyle and nutrition play a key role in its etiology. This study was designed to evaluate the age-related changes in the expression of major xenobiotic-metabolizing enzymes (XMEs) in the rat liver and the mammary gland in the dimethylbenz(a)anthracene-induced breast cancer model. The influence of dietary lipids on the ontogeny of XMEs was also evaluated. mRNA and protein levels of phase I (CYP1A1, CYP1A2, and CYP1B1) and phase II (NAD(P)H:quinone acceptor oxidoreductase 1 and GSTP1) enzymes were analyzed, as well as their regulation by AhR and Nrf2, respectively. Results showed differences in the phase I enzymes expression, whereas little changes were obtained in phase II. High corn oil and olive oil diets differentially influenced the expression of age-related changes, suggesting that the different susceptibility to xenobiotic exposure depending upon the age may be modulated by dietary factors.