Membrane gamma-glutamyl transferase activity promotes iron-dependent oxidative DNA damage in melanoma cells

Biomarkers of Hepatic Toxicity: An Overview

Background

Hepatotoxicity is the foremost issue for clinicians and the primary reason for pharmaceutical product recalls. A biomarker is a measurable and quantifiable attribute used to evaluate the efficacy of a treatment or to diagnose a disease. There are various biomarkers which are used for the detection of liver disease and the intent of liver damage.

Objective

This review aims to investigate the current state of hepatotoxicity biomarkers and their utility in clinical settings. Using hepatic biomarkers, the presence of liver injury, its severity, prognosis, causative agent, and type of hepatotoxicity can all be determined.

Methods

Relevant published articles up to 2022 were systematically retrieved from MEDLINE/PubMed, SCOPUS, EMBASE, and WOS databases using keywords such as drug toxicity, hepatotoxicity biomarkers, biochemical parameters, and nonalcoholic fatty liver disease.

Results

In clinical trials and everyday practice, biomarkers of drug-induced liver injury are essential for spotting the most severe cases of hepatotoxicity. Hence, developing novel biomarker approaches to enhance hepatotoxicity diagnosis will increase specificity and/or identify the person at risk. Importantly, early clinical studies on patients with liver illness have proved that some biomarkers such as aminotransferase, bilirubin, albumin, and bile acids are even therapeutically beneficial.

Conclusions

By assessing the unique signs of liver injury, health care professionals can rapidly and accurately detect liver damage and evaluate its severity. These measures contribute to ensuring prompt and effective medical intervention, hence reducing the risk of long-term liver damage and other major health concerns.

Advances and Perspectives of Responsive Probes for Measuring γ-Glutamyl Transpeptidase

Gamma-glutamyltransferase (GGT) is a plasma-membrane-bound enzyme that is involved in the γ-glutamyl cycle, like metabolism of glutathione (GSH). This enzyme plays an important role in protecting cells from oxidative stress, thus being tested as a key biomarker for several medical conditions, such as liver injury, carcinogenesis, and tumor progression. For measuring GGT activity, a number of bioanalytical methods have emerged, such as chromatography, colorimetric, electrochemical, and luminescence analyses. Among these approaches, probes that can specifically respond to GGT are contributing significantly to measuring its activity in vitro and in vivo. This review thus aims to highlight the recent advances in the development of responsive probes for GGT measurement and their practical applications. Responsive probes for fluorescence analysis, including "off-on", near-infrared (NIR), two-photon, and ratiometric fluorescence response probes, are initially summarized, followed by discussing the advances in the development of other probes, such as bioluminescence, chemiluminescence, photoacoustic, Raman, magnetic resonance imaging (MRI), and positron emission tomography (PET). The practical applications of the responsive probes in cancer diagnosis and treatment monitoring and GGT inhibitor screening are then highlighted. Based on this information, the advantages, challenges, and prospects of responsive probe technology for GGT measurement are analyzed.

Targeting gamma-glutamyl transpeptidase: A pleiotropic enzyme involved in glutathione metabolism and in the control of redox homeostasis

Gamma-glutamyl transpeptidase (GGT) is an enzyme located on the outer membrane of the cells where it regulates the metabolism of glutathione (GSH), the most abundant intracellular antioxidant thiol. GGT plays a key role in the control of redox homeostasis, by hydrolyzing extracellular GSH and providing the cell with the recovery of cysteine, which is necessary for de novo intracellular GSH and protein biosynthesis. Therefore, the upregulation of GGT confers to the cell greater resistance to oxidative stress and the advantage of growing fast. Indeed, GGT is upregulated in inflammatory conditions and in the progression of various human tumors and it is involved in many physiological disorders related to oxidative stress, such as cardiovascular disease and diabetes. Currently, increased GGT expression is considered a marker of liver damage, cancer, and low-grade chronic inflammation. This review addresses the current knowledge on the structure-function relationship of GGT, focusing on human GGT, and provides information on the pleiotropic biological role and relevance of the enzyme as a target of drugs aimed at alleviating oxidative stress-related diseases. The development of new GGT inhibitors is critically discussed, as are the advantages and disadvantages of their potential use in clinics. Considering its pleiotropic activities and evolved functions, GGT is a potential "moonlighting protein".

Inhibition of γ-glutamyl transferase suppresses airway hyperresponsiveness and airway inflammation in a mouse model of steroid resistant asthma exacerbation

Introduction

Despite recent advances, there are limited treatments available for acute asthma exacerbations. Here, we investigated the therapeutic potential of GGsTop, a γ-glutamyl transferase inhibitor, on the disease with a murine model of asthma exacerbation.

Methods

GGsTop was administered to mice that received lipopolysaccharide (LPS) and ovalbumin (OVA) challenges. Airway hyperresponsiveness (AHR), lung histology, mucus hypersecretion, and collagen deposition were analyzed to evaluate the hallmark features of asthma exacerbation. The level of proinflammatory cytokines and glutathione were determined with/without GGsTop. The transcription profiles were also examined.

Results

GGsTop attenuates hallmark features of the disease with a murine model of LPS and OVA driven asthma exacerbation. Airway hyperresponsiveness (AHR), mucus hypersecretion, collagen deposition, and expression of inflammatory cytokines were dramatically inhibited by GGsTop treatment. Additionally, GGsTop restored the level of glutathione. Using RNA-sequencing and pathway analysis, we demonstrated that the activation of LPS/NFκB signaling pathway in airway was downregulated by GGsTop. Interestingly, further analysis revealed that GGsTop significantly inhibited not only IFNγ responses but also the expression of glucocorticoid-associated molecules, implicating that GGsTop profoundly attenuates inflammatory pathways.

Conclusions

Our study suggests that GGsTop is a viable treatment for asthma exacerbation by broadly inhibiting the activation of multiple inflammatory pathways.

Utility of gamma-glutamyl transpeptidase to lymphocyte count ratio in predicting prognosis of patients with oral cancer: A prospective cohort study in Southeastern China

BACKGROUND

To assess the prognostic role of gamma-glutamyl transpeptidase to lymphocyte count ratio (GLR) and develop a prognostic nomogram for patients with oral cancer.

METHODS

A prospective cohort (n = 1011) was conducted during July 2002 to March 2021 in Southeastern China.

RESULTS

The median follow-up time was 3.5 years. Multivariate Cox regression (OS: HR = 1.51, 95% CI: 1.04, 2.18) and Fine-Gray model (DSS: HR = 1.68, 95% CI: 1.14, 2.49) both showed that high GLR could act as an indicator of poor prognosis. A nonlinear dose-response relationship was observed between continuous GLR and the risk of all-cause mortality (p for overall = 0.028, p for nonlinear = 0.048). Compare with TNM stage, time-dependent ROC curve proved that GLR-based nomogram model performs better in predicting prognosis (the area under curve for 1-, 3-, and 5-years mortality: 0.63, 0.65, and 0.64 vs. 0.76, 0.77, and 0.78, p < 0.001).

CONCLUSION

GLR might be a useful tool in predicting prognosis for patients with oral cancer.

Therapeutic drug monitoring and safety evaluation of voriconazole in the treatment of pulmonary fungal diseases

Aims:

The gene polymorphism of voriconazole metabolism–related liver enzyme is notable in East Asia population. It casts a significant influence on the rational use of voriconazole. We conducted this study to investigate the relationship between steady-state voriconazole trough concentration (C_trough) and adverse effects (AEs), especially hepatotoxicity.

Methods:

We conducted a real-world study in the Jinling Hospital from January 2015 to June 2020. A total of 140 patients receiving voriconazole were enrolled in this study. The determination and scoring of voriconazole-associated hepatotoxicity were performed according to the Roussel Uclaf Causality Assessment Method scoring scale and the severity of hepatotoxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE).

Results:

Elevated steady-state voriconazole C_trough with concomitant AEs are the most common reason for dose adjustments during treatment. Compared with the group without any AEs, voriconazole C_trough was significantly higher in the hepatotoxicity and neurotoxicity groups, and the incidence of both events showed an overall increasing trend with increasing voriconazole C_trough. Hepatotoxicity occurred in 66.7% of patients within 7 days of the first dose of voriconazole and 94.4% within 15 days of the dose. Steady-state voriconazole C_trough >3.61 mg/l was associated with an increased incidence of hepatotoxicity (area under the curve = 0.645, p = 0.047). Logistic regression analysis showed that timely voriconazole dose adjustment was a predictor of attenuated hepatotoxicity after adjustment for confounders, but hepatotoxicity was not associated with voriconazole C_trough measured at a single time point.

Conclusion:

Hepatotoxicity and neurotoxicity correlate with voriconazole C_trough, and dose reduction in patients with elevated steady-state voriconazole C_trough may prevent hepatotoxicity. In patients with early occurrence of hepatotoxicity, initial therapeutic drug monitoring (TDM) might predict the risk of hepatotoxicity. Follow-up TDM may be necessary to predict late onset hepatotoxicity.

Plain Language Summary

Safety of voriconazole for the treatment of pulmonary fungal diseases

Introduction: Several studies have suggested an association between the concentration of voriconazole in the blood and liver damage, but the evidence is weak. This study aimed to investigate relationships between voriconazole drug concentration and side effects and to analyze the factors affecting liver damage caused by voriconazole.

Methods: We conducted a study at the Jinling Hospital from January 2015 to June 2020, in which a total of 140 patients were finally enrolled.

Results: Voriconazole doses were adjusted in 44 patients due to abnormal voriconazole drug concentration or side effects, 32 patients reduced the dose and 8 patients increased the dose. An elevated liver enzyme level was the most common cause for dose adjustment. After the first dose adjustment, most patients achieved the target drug concentration. A total of 18 patients were determined as probable or highly probable to have drug-induced liver injury from voriconazole. Voriconazole drug concentration was significantly higher in the liver damage and nervous system damage groups as compared with the group without any side effects, and most liver damage events occurred within 14 days of the first dose. Voriconazole drug concentration >3.61 mg/l was associated with an increased incidence of liver damage.

Conclusion: In this study, approximately one-third of patients with pulmonary fungal disease needed to adjust their dose after the standard dose of voriconazole treatment. The incidence of liver damage and nervous system damage showed an overall increasing trend with increasing voriconazole baseline concentrations. Initial therapeutic drug monitoring may be predictive of liver damage. Follow-up monitoring of liver enzymes may be needed.

The AGH score is a predictor of disease-free survival and targeted therapy efficacy after liver transplantation in patients with hepatocellular carcinoma

BACKGROUND

Liver transplantation (LT) is the "cure" therapy for patients with hepatocellular carcinoma (HCC). However, some patients encounter HCC recurrence after LT. Unfortunately, there is no effective methods to identify the LT patients who have high risk of HCC recurrence and would benefit from adjuvant targeted therapy. The present study aimed to establish a scoring system to predict HCC recurrence of HCC patients after LT among the Chinese population, and to evaluate whether these patients are suitable for adjuvant targeted therapy.

METHODS

Clinical data of HCC patients who underwent LT from March 2015 to June 2019 were retrospectively collected and analyzed.

RESULTS

A total of 201 patients were included in the study. The multivariate Cox analysis suggested that preoperative alpha fetoprotein (AFP) > 200 µg/L (HR = 2.666, 95% CI: 1.515-4.690; P = 0.001), glutamyl transferase (GGT) > 96 U/L (HR = 1.807, 95% CI: 1.012-3.224; P = 0.045), and exceeding the Hangzhou criteria (HR = 2.129, 95% CI: 1.158-3.914; P = 0.015) were independent risk factors for poor disease-free survival (DFS) in patients with HCC who underwent LT. We established an AFP-GGT-Hangzhou (AGH) scoring system based on these factors, and divided cases into high-, moderate-, and low-risk groups. The differences in overall survival (OS) and disease-free survival (DFS) rates among the three groups were significant (P < 0.05). The efficacy of the AGH scoring system to predict DFS was better than that of the Hangzhou criteria, UCSF criteria, Milan criteria, and TNM stage. Only in the high-risk group, we found that lenvatinib significantly improved prognosis compared with that of the control group (P < 0.05).

CONCLUSIONS

The AGH scoring system provides a convenient and effective way to predict HCC recurrence after LT in HCC patients in China. Patients with a high-risk AGH score may benefit from lenvatinib adjuvant therapy after LT.

In utero exposure to parabens and early childhood BMI z-scores - Associations between placental ethyl paraben, longitudinal BMI trajectories and cord blood metabolic biomarkers

BACKGROUND

Parabens are used as antimicrobial preservatives in personal care products. Few studies have dealt with adverse health outcomes, transplacental transfer, and obesogenic effects of prenatal exposure to parabens. We examined the association between placental paraben levels and cord blood metabolic biomarkers, considering modulating effects of maternal pre-pregnancy BMI and underlying epigenetic mechanisms, and investigated longitudinal effects of in utero paraben exposure on early childhood trajectories of BMI z-scores.

METHODS

Placental concentrations of four parabens [methyl (MeP), ethyl (EtP), propyl (PrP), and butyl (BuP)] were measured by ultra-performance liquid chromatography/tandem mass spectrometry in 229 placentas of the ENVIRONAGE birth cohort. The association with cord blood metabolic biomarkers [glucose, insulin, γ-glutamyltransferase (GGT), high-density and low-density lipoprotein (HDL and LDL)] was analyzed in multiple regression models with two different sets of, a priori selected potential confounders, additionally stratified for different maternal BMI groups and assessed by causal mediation analysis. The association between placental paraben concentration and differential DNA methylation of CpGs annotated to GGT and longitudinal measurements of BMI z-scores were investigated with adjusted linear mixed models.

RESULTS

The geometric means of placental MeP, EtP, PrP, and BuP levels above the limit of detection (LOD) were 4.42, 1.32, 1.51, and 0.35 ng/g respectively, with only EtP showing sufficient (88%) measurements above LOD for further analyses. An interquartile ratio (IQR) increase in placental EtP was associated with an increase of 12.61 % (95% CI: 1.80 24.57) in the geometric mean of cord GGT activity, and with a decrease of -3.64 % (95% CI: -6.80 to -0.39) in the geometric mean of cord glucose. Placental EtP levels were significantly associated with hypermethylation of cg08612779 annotated to GGT7 after correcting for multiple testing (ß = 0.0017, p = 0.049). An interquartile ratio (IQR) increment in placental EtP was associated with a decrease in longitudinal BMI z-score of 0.27 points (95% CI: -0.46 to -0.088).

CONCLUSION

Prenatal EtP exposure may affect early childhood BMI. The association of placental EtP with cord blood GGT and glucose levels provides a starting point for further research on mechanisms of paraben-related metabolic processes in utero.

Development and Validation of Artificial Neural Networks for Survival Prediction Model for Patients with Spontaneous Hepatocellular Carcinoma Rupture After Transcatheter Arterial Embolization

Background

Spontaneous rupture bleeding is a fatal hepatocellular carcinoma (HCC) complication and a significant determinant of survival outcomes. This study aimed to develop and validate a novel artificial neural network (ANN)-based survival prediction model for patients with spontaneous HCC rupture after transcatheter arterial embolization (TAE).

Methods

Patients with spontaneous HCC rupture bleeding who underwent TAE at our hospital between January 2010 and December 2018 were included in our study. The least absolute shrinkage and selection operator (LASSO) Cox regression model was used to screen clinical variables related to prognosis. We incorporated the above clinical variables identified by LASSO Cox regression into the ANNs model. Multilayer perceptron ANNs were used to develop the 1-year overall survival (OS) prediction model for patients with spontaneous HCC ruptured bleeding in the training set. The area under the receiver operating characteristic curve and decision curve analysis were used to compare the predictive capability of the ANNs model with that of existing conventional prediction models.

Results

The median survival time for the whole set was 11.8 months, and the 1-year OS rate was 47.5%. LASSO Cox regression revealed that sex, extrahepatic metastasis, macroscopic vascular invasion, tumor number, hepatitis B surface antigen, hepatitis B e antigen, tumor size, alpha-fetoprotein, fibrinogen, direct bilirubin, red blood cell, and γ-glutamyltransferase were risk factors for OS. An ANNs model with 12 input nodes, seven hidden nodes, and two corresponding prognostic outcomes was constructed. In the training set and the validation set, AUCs for the ability of the ANNs model to predict the 1-year OS of patients with spontaneous HCC rupture bleeding were 0.923 (95% CI, 0.890–0.956) and 0.930 (95% CI, 0.875–0.985), respectively, which were higher than that of the existing conventional models (all P < 0.0001).

Conclusion

The ANNs model that we established has better survival prediction performance.

Risk of gastrointestinal cancer in patients with an elevated level of gamma-glutamyltransferase: A nationwide population-based study

Emerging evidence that an elevated serum gamma-glutamyltransferase (GGT) level is associated with an increased risk of gastrointestinal cancer, but still controversial. The aim of this study to assess the relationship between GGT level and risk of gastrointestinal cancer, and the contribution of the interaction of hyperglycemia with elevated GGT level to the incidence of gastrointestinal cancer by the stratified analysis. A total of 8,120,665 Koreans who received medical checkups in 2009 were included. Subjects were classified according to the quartile of GGT level for women and men. The incidence rates of gastrointestinal cancer for each group were analyzed using Cox proportional hazards models. During follow-up, 129,853 cases of gastrointestinal cancer newly occurred (esophagus, 3,792; stomach, 57,932; and colorectal, 68,789 cases). The highest GGT quartile group showed an increased risk of gastrointestinal cancer (esophagus, hazard ratio = 2.408 [95% confidence interval, 2.184–2.654]; stomach, 1.121 [1.093–1.149]; and colorectal, 1.185 [1.158–1.211]). The risk increased significantly with the rise in GGT quartile level, regardless of the site of cancer. The stratified analysis according to glycemic status showed that the effect of elevated GGT was predominant in the risk of esophageal cancer. The effect of elevated GGT further increased the risk of stomach and colorectal cancers in diabetic patients. An elevated level of GGT was associated with an increased risk of gastrointestinal cancer, regardless of the site of cancer. The effect of the increase in GGT level on the risk of gastrointestinal cancer depended on the type of cancer and glycemic status.

The dark side of gamma-glutamyltransferase (GGT): Pathogenic effects of an 'antioxidant' enzyme

Having long been regarded as just a member in the cellular antioxidant systems, as well as a clinical biomarker of hepatobiliary diseases and alcohol abuse, gamma-glutamyltransferase (GGT) enzyme activity has been highlighted by more recent research as a critical factor in modulation of redox equilibria within the cell and in its surroundings. Moreover, due to the prooxidant reactions which can originate during its metabolic function in selected conditions, experimental and clinical studies are increasingly involving GGT in the pathogenesis of several important disease conditions, such as atherosclerosis, cardiovascular diseases, cancer, lung inflammation, neuroinflammation and bone disorders. The present article is an overview of the laboratory findings that have prompted an evolution in interpretation of the significance of GGT in human pathophysiology.

Induction of Gamma-Glutamyltransferase Activity and Consequent Pro-oxidant Reactions in Human Macrophages Exposed to Crocidolite Asbestos

Asbestos is the main causative agent of malignant pleural mesothelioma. The variety known as crocidolite (blue asbestos) owns the highest pathogenic potential, due to the dimensions of its fibers as well as to its content of iron. The latter can in fact react with macrophage-derived hydrogen peroxide in the so called Fenton reaction, giving rise to highly reactive and mutagenic hydroxyl radical. On the other hand, hydroxyl radical can as well originate after thiol-dependent reduction of iron, a process capable of starting its redox cycling. Previous studies showed that glutathione (GSH) is one such thiol, and that cellular gamma-glutamyltransferase (GGT) can efficiently potentiate GSH-dependent iron redox cycling and consequent oxidative stress. As GGT is expressed in macrophages and is released upon their activation, the present study was aimed at verifying the hypothesis that GSH/GGT-dependent redox reactions may participate in the oxidative stress following the activation of macrophages induced by crocidolite asbestos. Experiments in acellular systems confirmed that GGT-mediated metabolism of GSH can potentiate crocidolite-dependent production of superoxide anion, through the production of highly reactive dipeptide thiol cysteinyl-glycine. Cultured THP-1 macrophagic cells, as well as isolated monocytes obtained from healthy donors and differentiated to macrophages in vitro, were investigated as to their expression of GGT and the effects of exposure to crocidolite. The results show that crocidolite asbestos at subtoxic concentrations (50-250 ng/1000 cells) can upregulate GGT expression, which raises the possibility that macrophage-initiated, GSH/GGT-dependent pro-oxidant reactions may participate in the pathogenesis of tissue damage and inflammation consequent to crocidolite intoxication.

Development and Validation of a Prognostic Nomogram to Predict the Long-Time Prognosis in Non-B, Non-C Hepatocellular Carcinoma

Purpose

To develop and validate a nomogram for individualized prediction of the long-term prognosis of patients with non-B, non-C hepatocellular carcinoma (NBNC-HCC) who underwent hepatectomy.

Materials and Methods

Five hundred ninety-four patients who met the criteria were included in the research and randomly categorized into the training or validation cohort. The nomogram was constructed on the basis of the independent risk variables that were acquired via multivariate Cox proportional hazard regression analysis. Several complementary methods included the Harrell c-index, time-dependent areas under the receiver operating characteristic curve (tdAUC), and calibration plot, and the Kaplan–Meier curve with Log rank test were used to test predictive performance of the model. The clinical utility of the model was tested by the decision cure analysis (DCA).

Results

Tumor diameter, tumor number, elevated serum gamma-glutamyl transpeptidase (GGT) level, microvascular invasion (MVI), and macrovascular invasion were independent risk factors of prognosis of NBNC-HCC. C-indexes of the nomogram were 0.702 (95% confidence interval [CI], 0.662–0.741) in the training cohort and 0.700 (95% CI, 0.643–0.758) in the validation cohort, and median tdAUC values of the nomogram were 0.743 (range, 0.736–0.775) in the training cohort and 0.751 (range, 0.686–0.793) in the validation cohort, which were both higher than those in the conventionally used Barcelona Clinic Liver Cancer staging system, American Joint Committee on Cancer, and eighth edition and the model of Zhang et al. The calibration plot depicted a good consistency between prediction of the model and observed outcome. The Kaplan–Meier curve analysis showed that the model was able to separate patients into three distinct risk subgroups. The DCA analysis also demonstrated that the nomogram was clinically useful.

Conclusion

We developed and validated a nomogram that was accurate and clinically useful in patients with NBNC-HCC who underwent hepatectomy.

Combined preoperative albumin-bilirubin (ALBI) and serum γ-glutamyl transpeptidase (GGT) predicts the outcome of hepatocellular carcinoma patients following hepatic resection

Background: Liver function is an important prognostic factor for patients with hepatocellular carcinoma. The purpose of this study was to develop and validate a nomogram integrating the albumin-bilirubin (ALBI) and serum γ-glutamyl transpeptidase (GGT) level to predict postoperative overall survival (OS) and disease-free survival (DFS) of hepatocellular carcinoma (HCC).

Methods: The effect of combined of ALBI and GGT on HCC prognosis was investigated using univariate and multivariate Cox analyses. The nomogram for OS and DFS were developed, respectively, and their predictive ability was compared with other conventional staging systems, including the American Joint Commission on Cancer (AJCC), Barcelona Clinic Liver Cancer (BCLC) and the Cancer of the Liver Italian Program (CLIP).

Results: Combined ALBI and GGT was highly associated with OS (P<0.001) and DFS (P<0.001) of HCC patients treated with hepatic resection. In addition, the C-index of the OS (0.706±0.034) or DFS (0.674±0.032) nomogram in the training cohort was larger than AJCC, BCLC and CLIP. The Akaike information criterion (AICs) of the OS (2178.405) or DFS (2961.018) nomogram in the training cohort was smaller than above staging systems. The results suggested that the OS or DFS nomogram was the most powerful model to predict HCC prognosis. The similar trend was observed in the validation cohort.

Conclusion: The novel nomogram integrating ALBI and GGT was highly associated with OS and DFS of postoperative HCC patients.

Sulfur-containing histidine compounds inhibit γ-glutamyl transpeptidase activity in human cancer cells

γ-Glutamyl transpeptidase (GGT) is an enzyme located on the surface of cellular membranes and involved in GSH metabolism and maintenance of redox homeostasis. High GGT expression on tumor cells is associated with increased cell proliferation and resistance against chemotherapy. GGT inhibitors evaluated so far in clinical trials are too toxic for human use. In this study, using enzyme kinetics analyses, we demonstrate that ovothiols, 5(Nπ)-methyl thiohistidines of marine origin, act as noncompetitive inhibitors of GGT, with an apparent K_i of 21 μm, when we fixed the concentrations of the donor substrate. We found that these compounds are more potent than the known GGT inhibitor 6-diazo-5-oxo-l-norleucine and are not toxic toward human embryonic cells. In particular, cellular process-specific fluorescence-based assays revealed that ovothiols induce a mixed cell-death phenotype of apoptosis and autophagy in GGT-overexpressing cell lines, including human liver cancer and chronic B leukemic cells. The findings of our study provide the basis for further development of 5-thiohistidines as therapeutics for GGT-positive tumors and highlight that GGT inhibition is involved in autophagy.

Gamma-glutamyltransferase as a preoperative differential diagnostic marker in patients with adnexal mass

OBJECTIVE

Gamma-glutamyltransferase (GGT) is involved in tumor development, progression and chemotherapy resistance. The present study evaluated GGT serum levels as a preoperative predictive marker for ovarian cancer in patients with adnexal mass.

STUDY DESIGN

Preoperative GGT serum levels of 2235 patients with adnexal mass and subsequent surgery were ascertained (patients with benign ovarian tumors: n = 1811; borderline tumor of the ovary [BTO]: n = 85; epithelial ovarian cancer [EOC]: n = 339). Standardized expert transvaginal ultrasound was documented.

RESULTS

Median (interquartile range) GGT serum levels in patients with benign ovarian tumors, BTO, and EOC were 15.0 U/l (11.0-23.0), 17.0 U/l (10.0-23.5), and 20.0 U/l (13.0-34.0), respectively (p = 0.002). Elevated GGT serum levels were associated with the presence of BTO/EOC in univariate analysis (p < 0.0001, hazard ratio 1.8, confidence interval 1.5-2.3). GGT did not outperform established tools for preoperative prediction of BTO/EOC in patients with adnexal mass, such as CA-125 measurement or transvaginal ultrasound.

CONCLUSION

Elevated GGT serum levels were not associated with the presence of BTO/EOC in women with suspicious adnexal mass in multivariate analysis. GGT serum levels did not outperform established risk factors and therefore might add only limited additional value to CA-125 serum levels in the differential diagnosis between benign and malignant adnexal masses.

Glutathione "Redox Homeostasis" and Its Relation to Cardiovascular Disease

More people die from cardiovascular diseases (CVD) than from any other cause. Cardiovascular complications are thought to arise from enhanced levels of free radicals causing impaired "redox homeostasis," which represents the interplay between oxidative stress (OS) and reductive stress (RS). In this review, we compile several experimental research findings that show sustained shifts towards OS will alter the homeostatic redox mechanism to cause cardiovascular complications, as well as findings that show a prolonged antioxidant state or RS can similarly lead to such cardiovascular complications. This experimental evidence is specifically focused on the role of glutathione, the most abundant antioxidant in the heart, in a redox homeostatic mechanism that has been shifted towards OS or RS. This may lead to impairment of cellular signaling mechanisms and elevated pools of proteotoxicity associated with cardiac dysfunction.

Prognostic and clinicopathological significance of Gamma-Glutamyltransferase in patients with hepatocellular carcinoma: A PRISMA-compliant meta-analysis

BACKGROUND

Many studies explored the prognostic and clinicopathological significance of pretreatment serum Gamma-Glutamyltransferase (GGT) level in hepatocellular carcinoma (HCC). However, there are inconsistent results in the prognostic and clinicopathological significance of pretreatment serum GGT level in HCC. Thus, we conducted this meta-analysis to comprehensively assess the prognostic and clinicopathological significance of pretreatment serum GGT level in HCC patients.

METHODS

We systematically searched PubMed, EMBASE and Web of Science for relevant studies (up to June 14, 2018). The estimated hazard ratios (HRs) were used to assess the association between pretreatment serum GGT level and survival in HCC patients. The estimated odds ratios (ORs) were applied to evaluate the correlation between pretreatment serum GGT and clinicopathological features in HCC.

RESULTS

Our results showed that high pretreatment serum GGT level was significantly correlated with poor overall survival (OS) (HR = 1.70, 95% CI: 1.54-1.87; P < .01) and disease-free survival/relapse-free survival (DFS/RFS) (HR = 1.56, 95% CI: 1.42-1.71; P < .01). Additionally, our results also revealed that there was a close correlation between GGT level and several clinicopathological features in HCC patients, including vascular invasion, tumor size, tumor number and Alpha-fetoprotein (AFP) level.

CONCLUSIONS

This meta-analysis shows that high pretreatment serum GGT level is significantly correlated with poor survival and unfavorable clinicopathological features in HCC patients, suggesting that pretreatment serum GGT may be an economical and effective prognostic biomarker for HCC patients. However, more high-quality studies are still warranted to further validate our findings, considering there are several limitations in this meta-analysis.

Substitutions in interferon sensitivity-determining region and hepatocarcinogenesis after hepatitis C virus eradication

BACKGROUND AND AIM

Amino-acid substitutions in the interferon sensitivity-determining region (ISDR) within the NS5A region are known to be associated with responsiveness to interferon (IFN)-based therapy. Additionally, previous studies reported that the ISDR was related to the development of hepatocellular carcinoma (HCC) in patients infected with hepatitis C virus (HCV). However, the association between substitutions in the ISDR and the development of HCC in patients who achieved sustained virological response (SVR) is unclear. The aim of this study was to clarify the association between amino-acid substitutions in the ISDR and development of HCC after SVR.

METHODS

One thousand five hundred eighty-eight patients infected with HCV who were treated with IFN-based therapy were enrolled, and 475 patients who achieved SVR and underwent complete virological analysis at pretreatment were investigated. HCV genotypes consisted of 1a (n = 10), 1b (n = 307), 2a (n = 110), 2b (n = 41), and 3a (n = 7), and the ISDR in each genotype was examined by direct sequencing.

RESULTS

Nineteen patients developed HCC after SVR. The cumulative incidence of HCC was 2.1% and 15.9% at 5 and 10 years after SVR, respectively. Multivariate analysis indicated older age (≥ 60 years: hazard ratio [HR], 3.23; P = 0.014), higher γ-glutamyl transpeptidase level (≥ 50 IU/L: HR, 8.42; P < 0.001) and ≥ 3 substitutions in the ISDR (HR, 3.24; P = 0.016) as independent factors that were significantly associated with HCC development.

CONCLUSION

Amino-acid substitutions in the ISDR are useful to predict not only IFN responsiveness but also HCC development in patients who achieved SVR by IFN-based therapy.

Role of β-Interferon Inducer (DEAE-Dextran) in Tumorigenesis by VEGF and NOTCH1 Inhibition along with Apoptosis Induction

As a novel target for breast cancer, interferon inducers have found its role as anti-angiogenic agents with diethylaminoethyl dextran (DEAE-Dextran) being a molecule used for centuries as a transfection agent. Our results herein offer an explanation for the emergence of DEAE-Dextran as an anti-tumor agent for TNBC with in-depth mechanistic approach as an anti-angiogenic molecule. DEAE-Dextran has found to possess cytotoxic activity demonstrated during the various in vitro cytotoxicity assays; moreover, as an anti-oxidant, DEAE-Dextran has shown to possess excellent reactive oxygen species scavenging activity. The interferon inducing capacity of DEAE-Dextran was determined qualitatively as well as quantitatively specifically demonstrating overexpression of β-interferon. As a measure of anti-proliferative activity, DEAE-Dextran exhibited reduced ki67, p53, and PCNA levels. Also, overexpression of CK5/6 and p63 in DEAE-Dextran treated animals indicated improvement in breast cell morphology along with an improvement in cell–cell adhesion by virtue of upregulation of β-catenin and E-cadherin. Anti-angiogenic property of DEAE-Dextran was concluded by the downregulation of CD31, VEGF, and NOTCH1 both in vivo and in vitro. Further, apoptosis due to DEAE-Dextran, initially determined by downregulation of Bcl2, was confirmed with flow cytometry. Overall, results are defensive of DEAE-Dextran as an emerging anti-tumor agent with mechanisms pertaining to β-interferon induction with probable VEGF and NOTCH1 inhibition as well as apoptosis which still needs to be studied in further depth.

Preoperative Albumin-Bilirubin Score for Postoperative Solitary Hepatocellular Carcinoma within the Milan Criteria and Child-Pugh A Cirrhosis

Surgical resection remains the initial treatment of choice for the majority of early stage hepatocellular carcinoma (HCC) patients. Although the factors that influence the prognosis of postoperative HCC patients have been well elucidated, there are a limited number of simple, objective, and distinct methods for estimating survival for postoperative patients with solitary HCC within the Milan criteria and Child-Pugh (C-P) A cirrhosis. The Albumin-Bilirubin (ALBI) score is a new evidence-based approach to assess liver function. The ALBI score eliminates subjective variables, such as ascites and encephalopathy which are the requirements for the conventional C-P grading system. This study enrolled 654 patients to determine whether the ALBI score can predict the outcomes of postoperative solitary HCC patients within the Milan criteria and C-P A cirrhosis. Our results showed the ALBI score significantly influenced the overall survival and cumulative recurrence rates. Furthermore, the ALBI score was significantly related to the degree of liver cirrhosis and serum γ-glutamyl transpeptidase (GGT) concentration in solitary HCC cases within the Milan criteria and C-P A cirrhosis. Additionally, the combination of the ALBI score and serum GGT concentration contributed to the prognosis prediction in this cohort. In conclusion, we externally validated the ALBI grade as a novel biomarker to predict prognosis for solitary HCC within the Milan Criteria and C-P A cirrhosis.

Association of serum gamma-glutamyltransferase and C-reactive proteins with neuromyelitis optica and multiple sclerosis

BACKGROUND

Many studies have demonstrated that serum gamma glutamyltransferase (GGT) within normal range might be an early marker of oxidative stress. However the role of GGT in neuromyelitis optica (NMO) and multiple sclerosis (MS) is unknown.

METHODS

We assessed the correlations among GGT and C-reactive protein (CRP) levels, as well as clinical characteristics of NMO and MS. Serum GGT and CRP levels were measured in 106 NMO patients, 87 MS patients, 79 patients with non-inflammatory neurological diseases (Parkinson disease) and 80 healthy controls (HC). Clinical parameters, blood-brain barrier (BBB) index and Delpech index of MS and NMO were also investigated.

RESULTS

We found that NMO patients had higher serum GGT and CRP levels within their normal ranges compared to MS, PD, healthy controls. NMO patients exhibited significantly higher EDSS scores than MS patients. The BBB index in NMO patients was significantly higher than that in MS patients. Significant correlations existed between serum GGT and CRP levels and EDSS scores, BBB index in NMO and MS patients.

CONCLUSION

Elevated GGT and CRP levels within their normal ranges in NMO and MS may be associated with inflammatory response, oxidative stress and BBB disturbance in the diseases. Further study into the underlying pathophysiology of this relationship is warranted.

Elevated serum gamma-glutamyltransferase is associated with an increased risk of oesophageal carcinoma in a cohort of 8,388,256 Korean subjects

Gamma-glutamyltransferase (GGT) is a marker for hepatic injury and alcohol consumption. However, the association of GGT with the risk of oesophageal carcinoma (OC) has not been fully recognized to date. Therefore, this study aimed to determine the association between elevated GGT and OC, by also considering the body mass index (BMI) of the subjects. Clinical data from 8,388,256 Korean individuals, who were aged 40 years and over and who received healthcare check-ups arranged by the national insurance program in 2007 and 2008, were analysed. Newly diagnosed OC was identified using claims data during a median follow-up duration of 8.72 years. During the study period, 6,863 individuals (0.08%) developed OC. We found that there was an increased risk of OC in subjects with serum GGT values >18 IU/L. Furthermore, a BMI <18.5 kg/m² (underweight) was associated with increased OC risk, while a BMI ≥23.0 kg/m² was associated with a reduced OC risk. Individuals who were both underweight and in the highest GGT quartile (≥40 IU/L) had a far greater risk of OC compared to other individuals (hazard ratio: 3.65, 95% confidence interval: 3.10–4.30). In conclusion, increased serum GGT was associated with an increased risk of developing OC in the general Korean population, regardless of age, sex, smoker status, or alcohol consumption.

Circulating gamma-glutamyl transferase and development of specific breast cancer subtypes: findings from the Apolipoprotein Mortality Risk (AMORIS) cohort

BACKGROUND

Different etiological pathways may precede development of specific breast cancer subtypes and impact prevention or treatment strategies. We investigated the association between gamma-glutamyl transferase (GGT) and development of specific breast cancer subtypes based on oestrogen receptor (ER), progesterone receptor (PR) and HER2 status.

METHODS

We included 231,283 cancer-free women in a Swedish cohort. Associations between GGT and breast cancer subtypes were investigated with nested case-control and case-case analyses. We used logistic regression models to assess serum GGT in relation to breast cancer subtype, based on individual and combined receptor status.

RESULTS

Positive associations were found between serum GGT and development of ER+, ER- and PR+ breast cancers compared to controls (odds ratio (OR) 1.14 (95% confidence interval (CI) 1.08-1.19), 1.11 (1.01-1.23) and 1.18 (1.12-1.24), respectively) and of ER+/PR+ tumours. We found inverse associations between GGT levels and PR- breast cancers compared to PR+ (OR 0.87 (0.80-0.95)), between ER+/PR- tumours compared to ER+/PR+ tumours and between ER-/PR-/HER+ compared to ER+/HER2 or PR+/HER2 tumours (OR 0.55 (95% CI 0.34-0.90).

CONCLUSION

The observed associations between pre-diagnostic serum GGT and different breast cancer subtypes may indicate distinct underlying pathways and require further investigations to tease out their clinical implications.

Serum liver enzymes serve as prognostic factors in patients with intrahepatic cholangiocarcinoma

Objective

Liver functions, reflective of the overall status of the host, have been reported to be important factors affecting the prognosis in many types of cancers. In this study, we explored the influences of liver enzymes albumin (ALB), globulin (GELO), total protein (TP), alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), direct bilirubin (DBIL), gamma glutamyltranspeptidase (GGT), and lactate dehydrogenase (LDH) on the overall survival (OS) in a number of 173 patients with intrahepatic cholangiocarcinoma (ICC).

Patients and methods

Between 2011 and 2015, we enrolled patients with pathologically proven locally advanced or metastatic ICC. The impact of ALB, GELO, TP, ALP, ALT, AST, TBIL, DBIL, GGT, and LDH on OS were analyzed using Kaplan–Meier analysis. Next, the associations between these liver enzymes and OS were evaluated by univariate and multivariate analyses. Finally, the role of these enzymes in OS was evaluated in the subgroups.

Results

Elevated liver enzymes were linked with OS. We revealed that independent prognostic factors of poor outcome were ALP, TBIL, DBIL, and GGT, whereas ALB is a protective factor in ICC patients.

Conclusion

Our results demonstrate that these liver enzymes may serve as valuable predictive markers in ICC patients.

Advances of diagnostic and mechanistic studies of γ-glutamyl transpeptidase in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the second major cause of cancerous deaths in the world, accounting for 80-90% of all cases of liver cancer with an assessed global incidence of 782,000 new cases and approximate 746,000 deaths in 2012. Preoperative laboratory data (des-γ carboxyprothrombin (DCP), α-fetoprotein (AFP), Indocyanine green retention 15 min (ICG-R15), and γ-glutamyl transferase (GGT)) should be completely assessed before deciding a treatment and predicting prognosis in order to improve the prognosis for patients with HCC. A few recent studies have suggested GGT as an independent prognostic indicator in cases with HCC. And the data of our and other research teams revealed that combination of GGT and ICG-R15 or other factors may improve the efficiency of GGT as a prognostic predictor. In addition of clinical studies, a few mechanistic studies had been performed and GGT was suggested to promote tumor progression and poor prognosis through inducing DNA damage and genome instability, releasing reactive oxygen species to activating invasion-related signaling pathway, blocking chemotherapy, regulating microRNAs, and managing CpG island methylation. Although there were a few mechanistic studies, further and accurate researches were still in need.

γ-Glutamyltransferase and Breast Cancer Risk Beyond Alcohol Consumption and Other Life Style Factors - A Pooled Cohort Analysis

Objective

Elevated γ-Glutamyltransferase serum levels are associated with increased risk of overall cancer incidence and several site-specific malignancies. In the present prospective study we report on the associations of serum γ-Glutamyltransferase with the risk of breast cancer in a pooled population-based cohort considering established life style risk factors.

Methods

Two cohorts were included in the present study, i.e. the Vorarlberg (n = 97,268) and the Malmoe cohort (n = 9,790). Cox proportional hazards regression models were fitted to estimate HRs for risk of breast cancer.

Results

In multivariate analysis adjusted for age, body mass index and smoking status, women with γ-Glutamyltransferase levels in the top quartile were at significantly higher risk for breast cancer compared to women in the lowest quartile (HR 1.21, 95% CI 1.09 to 1.35; p = 0.005). In the subgroup analysis of the Malmoe cohort, γ-Glutamyltransferase remained an independent risk factor for breast cancer when additionally considering alcohol intake. A statistically significant increase in risk was seen in women with γ-Glutamyltransferase-levels in the top versus lowest quartile in a multivariate model adjusted for age, body mass index, smoking status, physical activity, parity, oral contraceptive-use and alcohol consumption (HR 1.37, 95% CI 1.11–1.69, p = 0.006).

Conclusion

Our findings identified γ-Glutamyltransferase as an independent risk factor for breast cancer beyond the consumption of alcohol and other life style risk factors.

Gamma-Glutamyltransferase: A Predictive Biomarker of Cellular Antioxidant Inadequacy and Disease Risk

Gamma-glutamyltransferase (GGT) is a well-established serum marker for alcohol-related liver disease. However, GGT's predictive utility applies well beyond liver disease: elevated GGT is linked to increased risk to a multitude of diseases and conditions, including cardiovascular disease, diabetes, metabolic syndrome (MetS), and all-cause mortality. The literature from multiple population groups worldwide consistently shows strong predictive power for GGT, even across different gender and ethnic categories. Here, we examine the relationship of GGT to other serum markers such as serum ferritin (SF) levels, and we suggest a link to exposure to environmental and endogenous toxins, resulting in oxidative and nitrosative stress. We observe a general upward trend in population levels of GGT over time, particularly in the US and Korea. Since the late 1970s, both GGT and incident MetS and its related disorders have risen in virtual lockstep. GGT is an early predictive marker for atherosclerosis, heart failure, arterial stiffness and plaque, gestational diabetes, and various liver diseases, including viral hepatitis, other infectious diseases, and several life-threatening cancers. We review literature both from the medical sciences and from life insurance industries demonstrating that serum GGT is a superior marker for future disease risk, when compared against multiple other known mortality risk factors.

Prognostic significance of gamma-glutamyltransferase in patients with resectable esophageal squamous cell carcinoma

Gamma-glutamyltransferase (GGT) is a membrane-bound enzyme involved in the glutathione metabolism. Studies suggested that GGT was a marker of apoptotic balance and modulated tumor progression, invasion and drug resistance. Recently, GGT was shown to be associated with the progression of high-grade esophageal epithelial dysplasia to invasive carcinoma. This study was conducted to investigate the value of pre-therapeutic serum GGT levels as prognostic parameter in esophageal squamous cell carcinoma. Six hundred thirty-nine resectable esophageal squamous cell carcinoma patients were recruited in this study and were stratified into two GGT risk groups. The association of pre-therapeutic serum GGT levels and clinical-pathological parameters was examined. Univariate and multivariate survival analyses were performed. GGT serum levels were associated with gender, smoking status, TNM stage and lymph node involvement. Higher pre-therapeutic serum GGT was found in males, smoker, advanced TNM stage and lymph node positive patients. Patients assigned to the low-risk group had higher 5-year overall survival rate (53.1% vs. 33.0%, P < 0.01) and disease-free survival rate (45.2% vs. 23.4%, P < 0.01) than the high-risk group. Patients with high-risk group of GGT had 1.568 (95% confidence interval [CI], 1.259 ∼ 1.952) times the risk of death and 1.582 (95% CI, 1.286 ∼ 1.946) times the risk of disease recurrence contrast with those with low-risk group of GGT. The pre-therapeutic serum GGT is a novel independent prognostic parameter for disease-free survival and overall survival in resectable esophageal squamous cell carcinoma.

High Levels of Gamma-Glutamyl Transferase and Indocyanine Green Retention Rate at 15 min as Preoperative Predictors of Tumor Recurrence in Patients With Hepatocellular Carcinoma

This study investigated the preoperative independent risk factors associated with survival and recurrence for patients with hepatocellular carcinoma (HCC) who underwent hepatic resection. In total, 384 consecutive patients who underwent curative hepatic resection for single primary HCC were studied. Predictive factors associated with 1-, 3-, and 5-year survival and recurrence-free survival (RFS) were assessed using a univariate log-rank test and multivariate Cox proportional hazards regression model. Gamma-glutamyl transferase (GGT) > 100 U/L was identified as a preoperative independent risk factor affecting 1-, 3-, and 5-year survival whereas GGT > 50 U/L and indocyanine green retention 15 min (ICG-R15) > 10% were identified as preoperative independent risk factors affecting 1-, 3-, and 5-year RFS. The 384 patients studied had a 1-, 3-, and 5-year RFS rate of 72.8%, 43.3%, and 27%, respectively. Patients with GGT > 50 U/L had a 1-, 3-, and 5-year RFS rate of 64.5%, 36.0%, and 21.7%. These patients had lower survival rates than did patients with GGT ≤ 50 U/L (P < 0.05). Patients with GGT > 50 U/L and ICG-R15 > 10% had a 1-, 3-, and 5-year RFS rate of 62.4%, 29.5%, and 14.1%, respectively. These patients had lower survival rates than did patients in the other 2 groups with different levels of GGT and ICG (P < 0.05, respectively). The same was also true for patients with a tumor < 5 cm in size. Combined information in the form of high levels of GGT and ICG-R15 is a preoperative predictor that warrants full attention when evaluating tumor recurrence postoperatively.

Can gamma-glutamyl transferase levels contribute to a better prognosis for patients with hepatocellular carcinoma?

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. Hepatic resection has long been considered a main treatment option for HCC, but the high rate of recurrence after hepatic resection remains a problem that impacts the prognosis and survival of patients with HCC. Thus, clarifying the factors for survival and risk factors for tumor recurrence after hepatic resection is crucial. Imaging studies are currently emphasized before selecting a treatment and predicting the prognosis for patients with HCC. Recently, laboratory testing of des-gamma-carboxyprothrombin (DCP), alpha-fetoprotein (AFP), indocyanine green 15 min after administration (ICG-R15), and γ-glutamyl transpeptidase (γ-GTP) has garnered attention as a way to select treatment and predict the prognosis of patients with HCC. γ-GTP in particular has critical clinical significance as an indicator of prognosis. This indicator helps to predict prognosis and it helps with the selection of further treatment, as was revealed by studies based on different subgroups of patients published in the past 5 years. The reason for the association between γ-GTP and early recurrence and poor survival is being investigated. Preoperative laboratory results (DCP, AFP, ICG-R15, and γ-GTP) may warrant attention and need to be fully evaluated before selecting a treatment and predicting prognosis in order to improve the prognosis for patients with HCC.

Gamma-glutamyl transpeptidase: redox regulation and drug resistance

The expression of gamma-glutamyl transpeptidase (GGT) is essential to maintaining cysteine levels in the body. GGT is a cell surface enzyme that hydrolyzes the gamma-glutamyl bond of extracellular reduced and oxidized glutathione, initiating their cleavage into glutamate, cysteine (cystine), and glycine. GGT is normally expressed on the apical surface of ducts and glands, salvaging the amino acids from glutathione in the ductal fluids. GGT in tumors is expressed over the entire cell membrane and provides tumors with access to additional cysteine and cystine from reduced and oxidized glutathione in the blood and interstitial fluid. Cysteine is rate-limiting for glutathione synthesis in cells under oxidative stress. The induction of GGT is observed in tumors with elevated levels of intracellular glutathione. Studies in models of hepatocarcinogenesis show that GGT expression in foci of preneoplastic hepatocytes provides a selective advantage to the cells during tumor promotion with agents that deplete intracellular glutathione. Similarly, expression of GGT in tumors enables cells to maintain elevated levels of intracellular glutathione and to rapidly replenish glutathione during treatment with prooxidant anticancer therapy. In the clinic, the expression of GGT in tumors is correlated with drug resistance. The inhibitors of GGT block GGT-positive tumors from accessing the cysteine in extracellular glutathione. They also inhibit GGT activity in the kidney, which results in the excretion of GSH in the urine and a rapid decrease in blood cysteine levels, leading to depletion of intracellular GSH in both GGT-positive and GGT-negative tumors. GGT inhibitors are being developed for clinical use to sensitize tumors to chemotherapy.

Calpain-3 impairs cell proliferation and stimulates oxidative stress-mediated cell death in melanoma cells

Calpain-3 is an intracellular cysteine protease, belonging to Calpain superfamily and predominantly expressed in skeletal muscle. In human melanoma cell lines and biopsies, we previously identified two novel splicing variants (hMp78 and hMp84) of Calpain-3 gene (CAPN3), which have a significant lower expression in vertical growth phase melanomas and, even lower, in metastases, compared to benign nevi. In the present study, in order to investigate the pathophysiological role played by the longer Calpain-3 variant, hMp84, in melanoma cells, we over-expressed it in A375 and HT-144 cells. In A375 cells, the enforced expression of hMp84 induces p53 stabilization, and modulates the expression of a few p53- and oxidative stress-related genes. Consistently, hMp84 increases the intracellular production of ROS (Reactive Oxygen Species), which lead to oxidative modification of phospholipids (formation of F₂-isoprostanes) and DNA damage. Such events culminate in an adverse cell fate, as indicated by the decrease of cell proliferation and by cell death. To a different extent, either the antioxidant N-acetyl-cysteine or the p53 inhibitor, Pifithrin-α, recover cell viability and decrease ROS formation. Similarly to A375 cells, hMp84 over-expression causes inhibition of cell proliferation, cell death, and increase of both ROS levels and F₂-isoprostanes also in HT-144 cells. However, in these cells no p53 accumulation occurs. In both cell lines, no significant change of cell proliferation and cell damage is observed in cells over-expressing the mutant hMp84^C42S devoid of its enzymatic activity, suggesting that the catalytic activity of hMp84 is required for its detrimental effects. Since a more aggressive phenotype is expected to benefit from down-regulation of mechanisms impairing cell growth and survival, we envisage that Calpain-3 down-regulation can be regarded as a novel mechanism contributing to melanoma progression.

Association of gamma-glutamyltransferase with severity of disease at diagnosis and prognosis of ovarian cancer

Background:

Gamma-glutamyltransferase (GGT) – a membrane-bound enzyme crucially involved in the cell's detoxification pathway and apoptotic balance – is involved in tumour development, progression and chemotherapy resistance. Elevated GGT serum levels are associated with increased cancer risk in women and worse prognosis in gynaecologic cancers. The present study investigated the prognostic role of GGT in ovarian cancer patients.

Methods:

In this multicenter study, pre-therapeutic GGT levels were ascertained in 634 consecutive patients with epithelial ovarian cancer (EOC, n=567) and borderline tumour of the ovary (BTO, n=67). Gamma-glutamyltransferase serum levels were associated with clinicopathological parameters and uni- and multivariate survival analyses were performed. Immunohistochemistry of GGT was performed in ovarian cancer tissue and correlated with GGT serum levels.

Results:

Pre-therapeutic GGT serum levels were higher in patients with EOC (28.56 (38.24) U l⁻¹) than in patients with BTO (20.01 (12.78) U l⁻¹, P=0.01). High GGT serum levels were associated with advanced FIGO stage (P<0.001) and with worse overall survival in univariate (P<0.001) and multivariable analysis (P=0.02, HR 1.2 (1.1–1.5)). We further investigated the association between systemic GGT serum levels and local GGT expression in EOC tumour tissue and observed an association between these two parameters (P=0.03).

Conclusion:

High pre-therapeutic GGT serum levels are associated with advanced tumour stage and serve as an independent prognostic marker for worse overall survival in patients with EOC. Gamma-glutamyltransferase expression in ovarian cancer tissue is reflected in GGT serum levels.

Role of glutathione in cancer progression and chemoresistance

Glutathione (GSH) plays an important role in a multitude of cellular processes, including cell differentiation, proliferation, and apoptosis, and disturbances in GSH homeostasis are involved in the etiology and progression of many human diseases including cancer. While GSH deficiency, or a decrease in the GSH/glutathione disulphide (GSSG) ratio, leads to an increased susceptibility to oxidative stress implicated in the progression of cancer, elevated GSH levels increase the antioxidant capacity and the resistance to oxidative stress as observed in many cancer cells. The present review highlights the role of GSH and related cytoprotective effects in the susceptibility to carcinogenesis and in the sensitivity of tumors to the cytotoxic effects of anticancer agents.

Gamma-glutamyltransferase, general and cause-specific mortality in 19,000 construction workers followed over 20 years

BACKGROUND & AIMS

Associations of serum gamma-glutamyltransferase levels with a variety of incident diseases and mortality have been suggested. The present study attempted to expand the body of evidence to especially relevant occupational cohorts in which exposure to established γ-GT determinants may greatly differ from the general population.

METHODS

The study was based on occupational health examinations conducted from 1986 to 1992 in 19,090 German male workers from the construction industry, aged 25-64years. Sociodemographics and other health-related information were collected during the exam. Vital status follow-up was conducted through 2008. Associations of baseline γ-GT levels (measurements at 25°C) with all-cause and cause-specific mortality were examined by Kaplan-Meier plotting and multiple adjusted Cox regression models.

RESULTS

A total of 2170 deaths occurred during 303,198 person-years of follow-up. The risk of death due to any cause was 2.5-fold increased in subjects in the highest (⩾39U/L) versus lowest (<11U/L) γ-GT quintile. To varying extents, elevated γ-GT was associated with higher mortality due to cancer, circulatory, respiratory, and digestive causes, as well as accidents/poisoning.

CONCLUSIONS

The findings in this cohort provide evidence for γ-GT being associated with a broad range of causes of death, including less investigated outcomes. Some characteristics of the observed patterns need to be seen in the context of our cohort, featuring particularly high γ-GT levels.

Antitumoral and antioxidant effects of a hydroalcoholic extract of cat's claw (Uncaria tomentosa) (Willd. Ex Roem. & Schult) in an in vivo carcinosarcoma model

AIM OF THE STUDY

The present work intended to study the antitumoral and antioxidant effects of Uncaria tomentosa (UT) hydroalcoholic extract in the Walker-256 cancer model.

METHODS AND MATERIALS

Walker-256 cells were subcutaneously inoculated in the pelvic limb of male Wistar rats. Daily gavage with UT extract (10, 50 or 100 mg kg(-1), Groups UT) or saline solution (Control, Group C) was subsequently initiated, until 14 days afterwards. For some parameters, a group of healthy rats (Baseline, Group B) was added. At the end of treatment the following parameters were evaluated: (a) tumor volume and mass; (b) plasmatic concentration of urea, alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT) and lactate dehydrogenase (LDH); (c) hepatic and tumoral activity of catalase (CAT) and superoxide dismutase (SOD), as well as the rate of lipid peroxidation (LPO) and gluthatione (GSH); and (d) hepatic glutathione-S-transferase (GST) activity. The reactivity of UT extract with the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was assessed in parallel.

RESULTS

UT hydroalcoholic extract successfully reduced the tumor growth. In addition, treatment with UT reduced the activity of AST, which had been increased as a result of tumor inoculation, thus attempting to return it to normal levels. UT did not reverse the increase of LDH and GGT plasma levels, although all doses were remarkably effective in reducing urea plasma levels. An important in vitro free radical-scavenging activity was detected at various concentrations of UT extract (1-300 microg mL(-1)). Treatment also resulted in increased CAT activity in liver, while decreasing it in tumor tissue. SOD activity was reduced in liver as well as in tumor, compared to Group C. No statistical significance concerning ALT, GST, LPO or GSH were observed.

CONCLUSIONS

This data represent an in vivo demonstration of both antitumoral and antioxidant effects of UT hydroalcoholic extract. The antineoplastic activity may result, partially at least, from the ability of UT to regulate redox and metabolism homeostasis.

gamma-Glutamyl transferase and breast cancer risk

Background:

It has been reported that there is an increased risk of cancer in individuals with elevated levels of serum γ-glutamyl transferase (GGT).

Methods:

In the Guernsey Breast Cancer Cohort Study, GGT was measured in sera from 1803 normal women. Among these women, 251 subsequently developed cancer, of whom 96 developed breast cancer.

Results:

After adjustment for age at entry, height, weight, age at menarche and first birth with nulliparity, there was a highly significant relationship between elevated GGT and breast cancer risk. In the highest quartile, the hazard ratio (HR) was 2.17 (95% confidence interval (CI): 1.19, 3.93). When subdivided by menopausal status, there was a reduced non-significant effect in postmenopausal women, whereas for premenopausal women in the highest quartile, HR was 3.81 (95% CI: 1.37, 10.59). Premenopausal women with serum GGT levels above the normal range had a significantly elevated HR of 4.90 (95% CI: 1.86, 12.94).

Conclusions:

These results suggest that premenopausal women with high normal (above median) serum GGT or elevated levels (⩽40 IU l⁻¹) are at increased risk of breast cancer and might benefit from close surveillance, possibly with breast magnetic resonance imaging scans. Serum GGT may mark previous exposure to carcinogens and lead to the identification of DNA adducts involved in mammary carcinogenesis.