Glutathione S-transferase T1-1 activity upregulated in transitional cell carcinoma of urinary bladder

Urinary Exosomes from Bladder Cancer Patients Show a Residual Cancer Phenotype despite Complete Pathological Downstaging

Invasive urinary bladder cancer shows high recurrence rates after cystectomy even with apparent complete downstaging at cystectomy. Exosomes are nano-sized vesicles important in cell-cell communication, which have been hypothesized to contribute to cancer dissemination and recurrence. The aim of this study was to investigate if pro-carcinogenic exosomes could be detected in urine from histologically downstaged bladder cancer patients. 13 Patients were included in this study. Paired ureter and urine samples from nine patients underwent mass spectrometry, while samples from the remaining patients were used for exosome characterization. At cystectomy, exosomes were isolated from bladder and ureter urine, whereafter quantitative proteome profiling was performed. Urinary exosomes clustered based on whether they came from the bladder, with tumour contact, or the ureters, without tumour contact, even though all came from completely downstaged patients. Proteins overexpressed in exosomes derived from bladder urine contained several oncogenes and were mainly associated with tumour metabolism pathways. Although patients were histologically tumour-free at cystectomy, the bladder urine contained exosomes with a carcinogenic metabolic profile. This suggests a continuous release of exosomes from the bladder, which may promote recurrence at distant sites through metabolic rewiring, even after apparent complete downstaging. These exosomes, coming from either undetected cancer cells or partly transformed cells, are likely to increase the risk of metastasis and encourages cystectomy even in completely downstaged patients.

Approaches and Methods to Measure Oxidative Stress in Clinical Samples: Research Applications in the Cancer Field

Reactive oxygen species (ROS) are common by-products of normal aerobic cellular metabolism and play important physiological roles in intracellular cell signaling and homeostasis. The human body is equipped with antioxidant systems to regulate the levels of these free radicals and maintain proper physiological function. However, a condition known as oxidative stress (OS) occurs, when ROS overwhelm the body's ability to readily detoxify them. Excessive amounts of free radicals generated under OS conditions cause oxidative damage to proteins, lipids, and nucleic acids, severely compromising cell health and contributing to disease development, including cancer. Biomarkers of OS can therefore be exploited as important tools in the assessment of disease status in humans. In the present review, we discuss different approaches used for the evaluation of OS in clinical samples. The described methods are limited in their ability to reflect on OS only partially, revealing the need of more integrative approaches examining both pro- and antioxidant reactions with higher sensitivity to physiological/pathological alternations. We also provide an overview of recent findings of OS in patients with different types of cancer. Identification of OS biomarkers in clinical samples of cancer patients and defining their roles in carcinogenesis hold great promise in promoting the development of targeted therapeutic approaches and diagnostic strategies assessing disease status. However, considerable data variability across laboratories makes it difficult to draw general conclusions on the significance of these OS biomarkers. To our knowledge, no adequate comparison has yet been performed between different biomarkers and the methodologies used to measure them, making it difficult to conduct a meta-analysis of findings from different groups. A critical evaluation and adaptation of proposed methodologies available in the literature should therefore be undertaken, to enable the investigators to choose the most suitable procedure for each chosen biomarker.

Uroplakin IIIa Is a Marker in Bladder Cancer but Seems Not to Reflect Chemical Carcinogenesis

Background

Uroplakins are glycoproteins investigated as potential markers of urothelial carcinoma. However, their role in chemical carcinogenesis is uncertain. In this study the diagnostic value of plasma and urine uroplakin IIIa (UPIIIa) levels in bladder cancer (BC) was investigated, particularly in the aspect of environmental exposure to chemical carcinogens, measured by DNA damage and detoxification ability in the BC smoking group. The correlation between uroplakin, 8-OHdG, and GSTπ was investigated.

Material and Methods

This study included 61 BC patients and 33 healthy controls. UPIIIa, 8-OHdG, and GSTπ levels were estimated by the immunoenzymatic method (ELISA).

Results

UPIIIa levels were elevated in BC patients in plasma (p≤0.001) and in urine (p≤0.001), as were 8-OHdG and GSTπ levels in urine. Moreover, the 8-OHdG level was higher in invasive or high grade tumors. A positive correlation between UPIIIa/GSTπ and 8-OHdG/GSTπ was observed, but no UPIIIa/8-OHdG correlation was noted.

Conclusion

The study showed the diagnostic value of urine and plasma UPIIIa in BC (good sensitivity, specificity, and predictive value). The lack of UPIIIa correlation with 8-OHdG and smoking suggests that UPIIIa does not reflect the environmental exposure. The increased levels of 8-OHdG and GSTπ in the invasive tumor stage indicate their value in BC monitoring.

Upregulated glutathione transferase omega-1 correlates with progression of urinary bladder carcinoma

OBJECTIVES

Newly discovered glutathione transferase omega 1 (GSTO1-1) plays an important role in the glutathionylation cycle, a significant mechanism of protein function regulation. GSTO1-1 expression pattern has not been studied in transitional cell carcinoma (TCC), as yet.

METHODS

A total of 56 TCC tumor and corresponding non-tumor specimens were investigated. Glutathione content and thioltransferase activity were measured spectrophotometrically. Protein-glutathione mixed disulfides were measured fluorimetrically. GSTO1-1 expression was determined by immunoblot and qPCR. Immunoprecipitation with GSTO1-1 antibody was followed by immunoblot using anti-GSTO1, GSTP1, c-Jun, JNK, Akt, phospho-Akt, and ASK1 antibody, while for the total S-glutathionylation levels non-reducing electrophoresis was performed.

RESULTS

The contents of reduced glutathione and thioltransferase activity were significantly increased in tumor compared to non-tumor tissue. The increased GSTO1 expression in tumor tissue showed clear correlation with grade and stage. However, decreased total protein glutathionylation level in tumor compared to non-tumor samples was found. Immunoprecipitation has shown an association of GSTO1-1 with GSTP1, Akt, phospho-Akt, and ASK1 proteins.

CONCLUSIONS

GSTO1 deglutathionylase activity suggests its potential important role in redox perturbations present in TCC. Increased GSTO1-1 expression might contribute to TCC development and/or progression supporting the notion that GSTO1-1 may be a promising novel cancer target.

Recent Progress in Triple Negative Breast Cancer Research

Triple-negative breast cancer (TNBC) is defined as a type of breast carcinoma that is negative for expression of oestrogene and progesterone hormone receptors (ER, PR) and HER2. This form of breast cancer is marked by its aggressiveness, low survival rate and lack of specific therapies. Recently, important molecular characteristics of TNBC have been highlighted and led to the identification of some biomarkers that could be used in diagnosis, as therapeutic targets or to assess the prognosis. In this review, we summarize recent progress in TNBC research focusing on the genetic and epigenetic alterations of TNBC and the potential use of these biomarkers in the targeted therapy for better management of TNBC.

Glutathione S-transferase expression in upper urinary tract urothelial carcinomas: a Taiwan study

OBJECTIVES

Glutathione S-transferase (GST) isoenzymes play important roles in resistance to cell apoptosis and carcinogenesis. We aimed to establish the relationship between GST expression and the prognosis of upper urinary tract urothelial carcinoma (UTT-UC) in Taiwan.

METHODS

This study retrospectively reviewed 46 patients with pathologically confirmed UUT-UC at Kaohsiung Medical University Hospital. In each patient, expression of GSTT1 and GSTP1 was compared between urothelial carcinoma and normal urothelial cells by Western blotting.

RESULTS

GSTP1 expression in the UUT-UC cells was significantly higher than that in normal urothelial cells (1.6 fold, p<0.001). Expression of GSTT1 was significantly associated with the invasiveness of the carcinoma (p=0.006).

CONCLUSIONS

In UUT-UC, GSTP1 might be a potential tumor marker, whereas high GSTT1 expression could be used as an indicator of cancer progression. This study is the first to demonstrate potential applications of different GST isoenzymes for biomolecular analysis of UUT-UCs in Taiwan.

Polymorphisms of NRF2 and NRF2 target genes in urinary bladder cancer patients

PURPOSE

NRF2 transcription factor is involved in modulation of various antioxidant and metabolic genes and, therefore, may modulate anti-carcinogenic potential. Association between polymorphisms of NRF2 and five NRF2-regulated genes and urinary bladder cancer (BC) risk was analyzed.

METHODS

The study group included 244 BC patients, while the control group comprised 365 individuals with no evidence of malignancy. Genotyping of GSTM1 (deletion), GSTT1 (deletion), GSTA1 -69C/T (rs3957357), GSTP1 Ile105Val (rs1695), SOD2 Ala16Val (rs4880) and NRF2 -617C/A (rs6721961) in blood genomic DNA was performed by means of real-time PCR assays. The associations between gene polymorphism and BC risk were computed by logistic regression.

RESULTS

The frequency of GSTA1, GSTP1, SOD2 and NRF2 genotypes did not differ in both groups. A significantly higher BC risk was associated with GSTM1 null genotype after adjusting to age, sex and smoking habit (OR 1.85, 95 % CI 1.30-2.62; P = 0.001). GSTT1 null (OR 0.50, 95 % CI 0.31-0.81; P = 0.005) and GSTP1 Val105Val (OR 0.52, 95 % CI 0.27-0.98; P = 0.04) genotypes were associated with reduced BC risk separately or in combination (OR 0.24, 95 % CI 0.11-0.51; P < 0.0001) (P heterogeneity = 0.01). Combined GSTT1 null and SOD2 with at least one 16Val allele among never smokers encompass reduced BC risk (OR 0.14, 95 % CI 0.03-0.63; P = 0.01) (P heterogeneity = 0.04).

CONCLUSIONS

This study supports hypothesis that GSTM1 null genotype may be a moderate BC risk factor. The gene-gene and gene-environment interactions associated with combined GSTP1/GSTT1 and combined GSTT1/SOD2 genetic polymorphisms along with cigarette smoking habit may play a significant role in BC risk modulation.

Does occupational exposure to solvents and pesticides in association with glutathione S-transferase A1, M1, P1, and T1 polymorphisms increase the risk of bladder cancer? The Belgrade case-control study

OBJECTIVE

We investigated the role of the glutathione S-transferase A1, M1, P1 and T1 gene polymorphisms and potential effect modification by occupational exposure to different chemicals in Serbian bladder cancer male patients.

PATIENTS AND METHODS

A hospital-based case-control study of bladder cancer in men comprised 143 histologically confirmed cases and 114 age-matched male controls. Deletion polymorphism of glutathione S-transferase M1 and T1 was identified by polymerase chain reaction method. Single nucleotide polymorphism of glutathione S-transferase A1 and P1 was identified by restriction fragment length polymorphism method. As a measure of effect size, odds ratio (OR) with corresponding 95% confidence interval (95%CI) was calculated.

RESULTS

The glutathione S-transferase A1, T1 and P1 genotypes did not contribute independently toward the risk of bladder cancer, while the glutathione S-transferase M1-null genotype was overrepresented among cases (OR = 2.1, 95% CI = 1.1-4.2, p = 0.032). The most pronounced effect regarding occupational exposure to solvents and glutathione S-transferase genotype on bladder cancer risk was observed for the low activity glutathione S-transferase A1 genotype (OR = 9.2, 95% CI = 2.4-34.7, p = 0.001). The glutathione S-transferase M1-null genotype also enhanced the risk of bladder cancer among subjects exposed to solvents (OR = 6,5, 95% CI = 2.1-19.7, p = 0.001). The risk of bladder cancer development was 5.3-fold elevated among glutathione S-transferase T1-active patients exposed to solvents in comparison with glutathione S-transferase T1-active unexposed patients (95% CI = 1.9-15.1, p = 0.002). Moreover, men with glutathione S-transferase T1-active genotype exposed to pesticides exhibited 4.5 times higher risk in comparison with unexposed glutathione S-transferase T1-active subjects (95% CI = 0.9-22.5, p = 0.067).

CONCLUSION

Null or low-activity genotypes of the glutathione S-transferase A1, T1, and P1 did not contribute independently towards the risk of bladder cancer in males. However, in association with occupational exposure, low activity glutathione S-transferase A1 and glutathione S-transferase M1-null as well as glutathione S-transferase T1-active genotypes increase individual susceptibility to bladder cancer.

GSTA1, GSTM1, GSTP1, and GSTT1 polymorphisms and susceptibility to smoking-related bladder cancer: a case-control study

OBJECTIVES

Glutathione S-transferases (GSTs) are a family of enzymes involved in detoxification. Genes encoding for GSTA1, GSTM1, GSTP1, and GSTT1 proteins are polymorphic, which can result in complete or partial loss of enzyme activity. Previous studies have associated polymorphisms of GSTA1, GSTM1, and GSTP1 genes with a higher risk of bladder cancer, but this is still controversial. Potential role of GSTA1 polymorphism in susceptibility to bladder cancer in Whites is lacking. We examined association between GSTA1, GSTM1, GSTP1, and GSTT1 gene variants and bladder cancer risk and evaluated whether they were modified by smoking.

MATERIALS AND METHODS

A hospital-based case-control study recruited 201 incidence cases and 122 age-matched controls. Deletion polymorphism of GSTM1 and GSTT1 was identified by polymerase chain reaction method. Single nucleotide polymorphism of GSTA1 and GSTP1 was identified by restriction fragment length polymorphism method. Uniconditional multivariate logistic regression was applied to model association between genetic polymorphisms and bladder cancer risk, as well as effect modification by smoking.

RESULTS

No significant difference was observed in the distributions of GSTM1, GSTT1, GSTA1, and GSTP1 gene variants between patients and controls. None of the examined polymorphisms was significantly associated with bladder cancer risk independently. The results of gene-smoking interaction analyses indicated a significant combined effect of smoking and all common GST polymorphisms tested (P for trend = 0.001). However, the most significant effect on bladder cancer risk was observed in smokers carrying lower activity GSTA1-AB/BB and GSTM-null genotype (OR = 3.5, P < 0.05) compared with GSTA1-AA and GSTM1-active non-smokers. Overall, the risk observed did not significantly differ with respect to quantity of cigarettes smoked. However, heavy smokers with GSTM1-null genotype had 2 times higher risk of bladder cancer than GSTM1-null light smokers (OR = 4.8 vs. OR = 2.0) when GSTM1-active non-smokers served as reference group. Smokers carrying both GSTM1-null and GSTA1-AB + BB genotypes exhibited the highest risk of bladder cancer (OR = 2.00, P = 0.123).

CONCLUSIONS

Null or low-activity genotypes of the GSTA1, GSTM1, GSTT1, and GSTP1 did not contribute independently towards the risk of bladder cancer in our patients. However, in association with smoking, both low activity GSTA1 and GSTM1-null genotype increase individual susceptibility to bladder cancer.

Glutathione S-transferase T1, O1 and O2 polymorphisms are associated with survival in muscle invasive bladder cancer patients

Objective

To examine the association of six glutathione transferase (GST) gene polymorphisms (GSTT1, GSTP1/rs1695, GSTO1/rs4925, GSTO2/rs156697, GSTM1, GSTA1/rs3957357) with the survival of patients with muscle invasive bladder cancer and the genotype modifying effect on chemotherapy.

Patients and Methods

A total of 105 patients with muscle invasive bladder cancer were included in the study. The follow-up lasted 5 years. The effect of GSTs polymorphisms on predicting mortality was analyzed by the Cox proportional hazard models, while Kaplan-Meier analysis was performed to assess differences in survival.

Results

GSTT1 active, GSTO1 Asp140Asp or GSTO2 Asp142Asp genotypes were independent predictors of a higher risk of death among bladder cancer patients (HR = 2.5, P = 0.028; HR = 2.9, P = 0.022; HR = 3.9, P = 0.001; respectively) and significantly influenced the overall survival. There was no association between GSTP1, GSTM1 and GSTA1 gene variants with overall mortality. Only GSTO2 polymorphism showed a significant effect on the survival in the subgroup of patients who received chemotherapy (P = 0.006).

Conclusion

GSTT1 active genotype and GSTO1 Asp140Asp and GSTO2 Asp142Asp genotypes may have a prognostic/pharmacogenomic role in patients with muscle invasive bladder cancer.

GSTM1-null and GSTA1-low activity genotypes are associated with enhanced oxidative damage in bladder cancer

OBJECTIVES

To examine the association between gene variants of the detoxifying and antioxidant enzymes glutathione transferase M1 (GSTM1) and glutathione transferase A1 (GSTA1) and the extent of oxidative damage in patients with transitional cell carcinoma (TCC) of the urinary bladder.

METHODS

GSTM1 deletion polymorphism was identified by polymerase chain reaction, and the restriction fragment length polymorphism method was used for the single nucleotide polymorphism of GSTA1. Enzyme immunoassay was used to determine markers of DNA (8-hydroxy-2′-deoxyguanosine, 8-OHdG) and lipid (8-epiprostaglandin F2α) oxidative damage in the urine of 80 TCC patients and 60 age-matched controls.

RESULTS

Urinary 8-OHdG and 8-epi-prostaglandin F2α concentrations in TCC patients were significantly higher than in controls (P=0.043 and 0.001, respectively). GSTM1 and GSTA1 polymorphisms influence vulnerability to both DNA and lipid oxidation, with the GSTM1-null gene variant having a more pronounced effect. A significant effect of combined GSTM1 and GSTA1 genotypes on the extent of oxidative damage was found only for 8-OHdG (P=0.018). In addition, TCC patients with the most malignant tumors exhibited significantly higher frequencies of GSTM1-null or GSTA1-low activity genotypes, associated with a twofold increase in urinary 8-OHdG concentration (P=0.044).

CONCLUSIONS

Our results suggest that absent GSTM1 or reduced GSTA1 antioxidant activity may increase the accumulation of oxidative DNA damage, thereby contributing to the malignant potential of TCC.

MiR-133a induces apoptosis through direct regulation of GSTP1 in bladder cancer cell lines

OBJECTIVE

We previously demonstrated that miR-133a is a tumor-suppressive microRNA (miRNA) and is commonly down-regulated in human bladder cancer (BC). The aim of this study is to determine a novel oncogenic gene targeted by miR-133a in BC.

METHODS

To identify genes targeted by miR-133a, an oligo-microarray analysis was performed using the miR-133a-transfected BC cell lines. For gain/loss-of-function studies, miR-133a/si-glutathione S-transferase π1 (GSTP1)-transfectants were subjected to XTT assay and flow cytometry to evaluate their cell viability and apoptosis status. The luciferase reporter assay was used to confirm the actual binding sites between miR-133a and GSTP1 mRNA. The mRNA and protein expression of GSTP1 in BC cell lines and clinical samples were evaluated by real-time RT-PCR and Western blot, respectively.

RESULTS

MiR-133a transfection induced cell viability inhibition and apoptosis in BC cell lines. We focused on the GSTP1 gene that was the top 7 down-regulated one in the gene profile from the miR-133a-transfectants. MiR-133a transfection repressed expression levels of mRNA and protein levels of GSTP1. A luciferase reporter assay suggested that the actual binding may occur between miR-133a and GSTP1 mRNA. Cell viability inhibition and apoptosis were induced in the si-GSTP1 transfectants compared with the controls (P < 0.005). GSTP1 mRNA expression levels in 43 clinical BCs were significantly higher than those in eight normal bladder epitheliums (P = 0.0277).

CONCLUSION

Our data suggest that tumor suppressive miR-133a directly regulated oncogenic GSTP1 gene in BC, and that an anti-apoptotic effect mediated by GSTP1 is maintained by miR-133a down-regulation in human BC.

GSTT1: a marker of the aggressiveness of bladder cancer

INTRODUCTION

Glutathione S-transferases have been implicated in the development of bladder cancer (BC). We investigated the genotype and expression of glutathione S-transferase-mu (GSTM1) and glutathione S-transferase-theta (GSTT1) in BC tissue specimens.

MATERIALS AND METHODS

Tumor samples and matched normal mucosae were obtained from 34 patients. Genomic DNA was used to analyze GSTM1 and GSTT1 genotypes using multiplex polymerase chain reaction. GSTM1 and GSTT1 mRNA levels were measured using real-time reverse transcriptase polymerase chain reaction.

RESULTS

GSTM1 mRNA expression was lower in tumor tissues than in matched normal bladder mucosae, whereas GSTT1 mRNA expression was significantly higher. GSTT1 mRNA expression was higher in muscle-invasive BC and high-grade cancers than in non-muscle-invasive BC and lower-grade tumors.

CONCLUSIONS

GSTT1 is correlated with characteristics of aggressive BC. GSTT1 may play an important role in tumorigenesis and disease progression in patients with BC.

Co-localization of GSTP1 and JNK in transitional cell carcinoma of urinary bladder

Transitional cell carcinoma (TCC) of urinary bladder belongs to glutathione S-transferase P1 (GSTP1) overexpressing tumors. Upregulated GSTP1 in TCC is related to apoptosis inhibition. This antiapoptotic effects of GSTP1 might be mediated through protein:protein interaction with c-Jun NH₂ -terminal kinase (JNK). Herein, we analyzed whether a direct link between GSTP1 and JNK exists in TCC. The presence of GSTP1/JNK complexes was analyzed by immunoprecipitation and Western blotting in 20 TCC specimens, obtained after surgery. Co-localization of GSTP1 and JNK was also investigated in the 5637 TCC cell line by immunofluorescence confocal microscopy. By means of immunoprecipitation we show for the first time the presence of GSTP1/JNK complexes in all TCC samples studied. A co-localization of GSTP1 and JNK was also demonstrated in the 5637 TCC cell line by means of confocal microscopy. Protein-protein interactions, together with co-localization between GSTP1 and JNK provide evidence that GSTP1 most probably inhibits apoptosis in TCC cells by non-covalent binding to JNK.

Isoenzyme profile of glutathione transferases in transitional cell carcinoma of upper urinary tract

Upregulated glutathione S-transferase P1 (GSTP1) plays an important role in the resistance to apoptosis in transitional cell carcinoma (TCC) of the urinary bladder (UB) and represents a potential target for chemotherapeutic agents. Our aim was to perform a systematic investigation of a glutathione S-transferase (GST) isoenzyme profile (GSTM, GSTP1, and GSTT1) in the upper urinary tract (UUT) TCC and compare it with the GST isoenzyme pattern of the UB TCC and normal urothelium. We examined GST activity spectrophotometrically by using substrates for the overall GST activity, GSTP1, and GSTT1 in the cytosolic fraction. GSTP1 and GSTM expression was analyzed by Western blotting. The results obtained have shown that the overall GST activity was significantly higher in UUT TCC in comparison with urothelium (P<0.001), which gradually increases with tumor grade (P<0.05). The mean GSTP1 and GSTT1 activities in UUT TCC were 2- and 3.6-fold higher, respectively, than in the normal urothelium (P<0.001), and these values did not differ significantly from activities found in the UB TCC. GSTM was expressed in 42% of the UUT TCC and 50% of the UB TCC specimens. The level of GSTM expression was slightly increased in the UUT TCC specimens in comparison with normal urothelium (P>0.05). We conclude that 3 major cytosolic GST classes, GSTM, GSTP1, and GSTT1, are expressed in the UUT TCC. The isoenzyme profile of GST in the UUT TCC is similar to that observed in the UB TCC; it shows essentially the same alteration of the GST phenotype in the course of cancerization. The association of GSTT1 and GSTP1 upregulation with the malignant phenotype of the UUT TCC might result in resistances to both chemotherapy and apoptosis.

Copy number alterations and expression profiles of candidate genes in a pulmonary inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumor (IMT) is a soft tissue neoplasm composed of myofibroblastic spindle cells accompanied by the inflammatory infiltrate. In addition to its phenotypic ambiguity, pathogenic mechanisms of the IMT also remain elusive. Although several chromosomal aberrations have been identified by karyotyping, detailed characteristics and extent of copy number alterations in IMT are unknown. Copy number alterations of an IMT case were examined using 30K whole-genome oligoarray-comparative genomic hybridization. RNA expression of putative cancer-related genes located in the chromosomal altered regions was assessed by qRT-PCR. We identified seven copy number gained regions, seven lost regions, nine amplifications and six homozygous deletions, which covers 2.5% of total genome. In homozygously deleted regions, RNA levels of putative tumor suppressors, SEMA3B, SEMA3F and SULT2A1, were significantly repressed being consistent with copy number status. In high-level amplification regions, RNA expression of four potential cancer-related genes was examined; GSTT1, ESR1, EVI1 and MITF. Among them, GSTT1 and ESR1 were significantly up-regulated, but EVI1 and MITF showed insignificant elevation of RNA expression. To our knowledge, this is the first genome-wide analysis of copy number alterations in IMT. Most of the putative cancer-related genes identified in this study are supposedly novel in IMT. Taken together, our results will help to elucidate the pathogenic mechanisms of IMT.

Expression of glutathione-S-transferases isoenzymes and p53 in exfoliated human bladder cancer cells

OBJECTIVES

This study investigates the usefulness of glutathione-S-transferases (GST) isoenzymes and p53 immunostaining as a marker of malignancy in urinary cytology, and evaluates their potential effect in increasing diagnostic accuracy in a series of urine cytologic samples. They are also correlated with cytopathology diagnosis and histopathologic diagnosis.

MATERIALS AND METHODS

In this study, the slides from 124 bladder carcinoma patients prepared by the cytocentrifugation method were observed. The cytomorphologic properties of these cancer cells were determined. Moreover, the immunocytochemical distributions of GST alpha (GSTA), pi (GSTP), mu (GSTM4), theta (GSTT1) isoenzymes and p53 protein were studied for the patients.

RESULTS

The urothelial cancer cells had small cytoplasm and rough nuclear membrane. The chromatin granules were heterogeneously distributed in each malignant cell's nucleus. There was a pleomorphism of the malignant cells' nuclei. According to immunocytopathologic observations, the urothelial cancer cells had stronger staining intensity than the benign cells had in 48% of cases for GSTA, 46% of cases for GSTP, 38% of cases for GSTM4, and 42% of cases for GSTT1. For all papillary cases, the malignant cells were stained negative, while the benign cells were positive. For 83% of patients, the malignant cells were stained positive for p53. There was a significant difference in GSTA (P = 0.006), GSTT1 (P = 0.004), GSTP (P = 0.000) and p53 (P = 0.000) expressions for benign cells whereas, a non-statistical difference in the malignant cells for GSTA, GSTT1, GSTP, GSTM4, and p53 expressions (P > 0.05).

CONCLUSIONS

GST isoenzymes and p53 immunostaining were not found to be markers of malignancy in urinary cytology.

Glutathione S-Transferase-P1 Expression Correlates with Increased Antioxidant Capacity in Transitional Cell Carcinoma of the Urinary Bladder

OBJECTIVES

Our aim was to perform a comprehensive analysis of the antioxidant capacity of transitional cell carcinoma (TCC) of urinary bladder and discern the role of enzymes associated with glutathione (GSH) in maintaining high GSH levels in these tumours. Because the redox-sensitive protein glutathione S-transferase P1 (GSTP1) might provide an important link between high antioxidant capacity and inhibition of apoptotic pathways, we also explored how the redox state in tumour cells interacts with the expression of GSTP1.

METHODS

We examined spectrophotometrically the specific activities of GSH-replenishing enzymes involved in GSH synthesis (gamma-glutamylcysteine synthetase, gamma-GCS), GSH regeneration (glutathione reductase, GR), and antioxidant protection (glutathione peroxidase, GPX; superoxide dismutase, SOD) in the cytosolic fraction of tumours and the surrounding normal tissue of 30 TCC patients. GSTP1-1 expression was also analyzed.

RESULTS

We found a significant increase in the activity of both GSH-replenishing and antioxidant enzymes as well as enhanced GSTP1-1 expression in tumours in comparison with adjacent normal uroepithelium. Mean gamma-GCS and GR activities in tumours were about 4- and 2-fold higher, respectively, than in corresponding normal tissue. Expression of GSTP1 correlated significantly with GSH level and gamma-GCS and GR activities. GPX and SOD activities in TCC were also markedly increased.

CONCLUSIONS

Enhanced GSH-replenishing pathways account for increased GSH levels in TCC. Upregulated GPX and SOD also contribute to high antioxidant potential in TCC. Under such conditions, expression of redox-sensitive GSTP1 protein is upregulated.

Glutathione S-transferase: differential expression of alpha, mu, and pi isoenzymes in benign prostate, prostatic intraepithelial neoplasia, and prostatic adenocarcinoma

Glutathione S-transferases (GST) comprise a family of enzymes which are critical for inactivation of toxins and carcinogens. We examined the cellular expression of multiple subclasses of GST immunohistochemically in 25 radical prostatectomy specimens with clinically localized prostate cancer. Gleason scores ranged from 5 to 9, and pathologic stages varied from pT2a to pT3b (all N0M0). Antibodies were directed against GST Ya, Yc, and Yk (alpha subclass), Yb1 (micro subclass), and YPr (pi subclass). The percentage of positive cells and intensity of staining was assessed for benign epithelium, high-grade prostatic intraepithelial neoplasia (PIN), and adenocarcinoma. GSTalpha (Ya) was detected in 30% of cells (mean) in benign acini, 4.9% of cells in high-grade PIN, and 4.5% of cells in adenocarcinoma. The corresponding results for alpha (Yk), micro (Yb1), and pi (Yp) were 12.7%, 10.9%, and 3.5%; 8.7%, 5.2%, and 0.6%; and 66.7,% 0%, and 0%, respectively. GST Yc (alpha subclass) displayed the lowest level of expression, with diffuse weak staining in scattered benign secretory cells and only single cells (<1%) in high-grade PIN and carcinoma. These results demonstrate consistent reduction or loss of expression of all subclasses of GST with progression of prostatic neoplasia from benign epithelium to high-grade PIN and carcinoma. We hypothesize that carcinogenesis in the prostate results from impaired cellular handling of mutagenic agents owing to reduction or loss of expression of multiple GST and other detoxifying and antimutagenesis agents.

Glutathione S-transferase pi (GSTP1) hypermethylation in prostate cancer: review 2007

Prostatic carcinoma is characterised by the silencing of the pi-class glutathione S-transferase gene (GSTP1), which encodes a detoxifying enzyme. The silencing of GSTP1 results from aberrant methylation at the CpG island in the promoter-5' and occurs in the vast majority of cases of high-grade prostatic intraepithelial neoplasia (PIN) and prostate cancers. We review the potential novel role of GSTP1 and its related expression in prostate cancer. The loss of expression (silencing) of the GSTP1 gene is the most common (>90%) genetic alteration reported to date in prostate cancer. Quantitative methylation-specific PCR assays allow detection of GSTP1 methylation in prostate biopsies and may improve the sensitivity of cancer detection. Advances in the epigenetic characterisation of prostate cancer have enabled the development of DNA methylation assays that may soon be used in diagnostic testing of serum and tissue for prostate cancer. Inhibition of aberrant promoter methylation could theoretically prevent carcinogenesis.