Involvement of γ-Glutamyl Transpeptidase in Ischemia/Reperfusion-Induced Cardiac Dysfunction in Isolated Rat Hearts.

GGsTop is a highly potent and specific, and irreversible γ-glutamyl transpeptidase (GGT) inhibitor without any influence on glutamine amidotransferases. The aim of the present study was to investigate the involvement of GGT in ischemia/reperfusion-induced cardiac dysfunction by assessing the effects of a treatment with GGsTop. Using a Langendorff apparatus, excised rat hearts underwent 40 min of global ischemia without irrigation and then 30 min of reperfusion. GGT activity was markedly increased in cardiac tissues exposed to ischemia, and was inhibited by the treatment with GGsTop. Exacerbation of cardiac functional parameters caused by ischemia and reperfusion, namely the reduction of left ventricular (LV) developed pressure and the maximum and negative minimum values of the first derivative of LV pressure, and the increment in LV end-diastolic pressure was significantly attenuated by GGsTop treatment. The treatment with GGsTop suppressed excessive norepinephrine release in the coronary perfusate, a marker for myocardial dysfunction, after ischemia/reperfusion. In addition, oxidative stress indicators in myocardium, including superoxide and malondialdehyde, after ischemia/reperfusion were significantly low in the presence of GGsTop. These observations demonstrate that enhanced GGT activity contributes to cardiac damage after myocardial ischemia/reperfusion, possibly via increased oxidative stress and subsequent norepinephrine overflow. GGT inhibitors have potential as a therapeutic strategy to prevent myocardial ischemia/reperfusion injury in vivo.

Proteome analysis of human embryonic stem cells organelles.

As the functions of proteins are associated with their cellular localization, the comprehensive sub-cellular proteome knowledge of human embryonic stem cells (hESCs) is indispensable for ensuring a therapeutic effect. Here, we have utilized a sub-cellular proteomics approach to analyze the localization of proteins in the nucleus, mitochondria, crude membrane, cytoplasm, heavy and light microsomes. Out of 2002 reproducibly identified proteins, we detected 762 proteins in a single organelle whereas 160 proteins were found in all sub-cellular fractions. We verified the localization of identified proteins through databases and discussed the consistency of the obtained results. With regards to the ambiguity in the definition of a membrane protein, we tried to clearly define the plasma membrane, peripheral membrane and membrane proteins by annotation of these proteins in databases, along with predictions of transmembrane helices. Among ten enriched signaling pathways highlighted in our results, non-canonical Wnt signaling were analyzed in greater detail. The functions of three novel hESC membrane proteins (ERBB4, GGT1 and ZDHHC13) have been assessed in terms of pluripotency. Our report is the most comprehensive for organellar proteomics of hESCs. SIGNIFICANCE: Mass spectrometric identification of proteins using a TripleTOF 5600 from nucleus, mitochondria, crude membrane, cytoplasm, heavy and light microsomal fractions highlighted the significance of the non-canonical Wnt signaling in human embryonic stem cells.

Role of bacterial γ-glutamyltranspeptidase as a novel virulence factor in bone-resorbing pathogenesis.

Mammalian γ-glutamyltranspeptidase (GGT) has been identified as a bone-resorbing factor. Since GGT of Bacillus subtilis exhibits similarity in their primary structure and enzymatic characteristics with mammalian GGTs, the bone-resorbing activity of bacterial GGT was examined in this study. Osteoclastogenesis was performed in a co-culture system of mouse calvaria-derived osteoblasts and bone marrow cells. A conditioned medium from GGT-overproducing B. subtilis culture showed significantly higher activity of osteoclast formation than a conditioned medium from wild-type B. subtilis culture. Recombinant GGT (rGGT) of wild-type B. subtilis and an enzymatic activity-defected rGGT of B. subtilis 2288 mutant were expressed in Escherichia coli and purified using His tag. Both purified rGGTs induced similar levels of osteoclastogenesis, suggesting that B. subtilis GGT possesses virulent bone-resorbing activity and its activity is probably independent of its enzymatic activity. Furthermore, a recombinant protein of B. subtilis GGT heavy subunit (Bs rGGT/H) showed strong activity of osteoclastogenesis while the light subunit failed to show strong activity, suggesting that the bone-resorbing activity is mainly located at the heavy subunit. More importantly, the GGT enzymatic activity may not be required for this virulence activity since the light subunit contains the catalytic pocket. In addition, B. subtilis rGGT stimulated mRNA expressions of receptor activator of nuclear factor kappa-B ligand (RANKL) and cyclooxygenase-2 (COX-2), while an osteoprotegerin inhibited the osteoclast formation induced by Bs rGGT/H. This is the first demonstration that bacterial GGT itself is sufficient to act as a bone-resorbing virulence factor via RANKL-dependent pathway. Therefore, it can be hypothesized that GGT of periodontopathic bacteria may play an important role as a virulence factor in bone destruction.

Instrumental Role of Helicobacter pylori γ-Glutamyl Transpeptidase in VacA-Dependent Vacuolation in Gastric Epithelial Cells.

Helicobacter pylori causes cellular vacuolation in host cells, a cytotoxic event attributed to vacuolating cytotoxin (VacA) and the presence of permeant weak bases such as ammonia. We report here the role of γ-glutamyl transpeptidase (GGT), a constitutively expressed secretory enzyme of H. pylori, in potentiating VacA-dependent vacuolation formation in H. pylori-infected AGS and primary gastric cells. The enhancement is brought about by GGT hydrolysing glutamine present in the extracellular medium, thereby releasing ammonia which accentuates the VacA-induced vacuolation. The events of vacuolation in H. pylori wild type (WT)- and Δggt-infected AGS cells were first captured and visualized by real-time phase-contrast microscopy where WT was observed to induce more vacuoles than Δggt. By using semi-quantitative neutral red uptake assay, we next showed that Δggt induced significantly less vacuolation in AGS and primary gastric epithelial cells as compared to the parental strain (P<0.05) indicating that GGT potentiates the vacuolating effect of VacA. Notably, vacuolation induced by WT was significantly reduced in the absence of GGT substrate, glutamine (P<0.05) or in the presence of a competitive GGT inhibitor, serine-borate complex. Furthermore, the vacuolating ability of Δggt was markedly restored when co-incubated with purified recombinant GGT (rGGT), although rGGT itself did not induce vacuolation independently. Similarly, the addition of exogenous ammonium chloride as a source of ammonia also rescued the ability of Δggt to induce vacuolation. Additionally, we also show that monoclonal antibodies against GGT effectively inhibited GGT activity and successfully suppressed H. pylori-induced vacuolation. Collectively, our results clearly demonstrate that generation of ammonia by GGT through glutamine hydrolysis is responsible for enhancing VacA-dependent vacuolation. Our findings provide a new perspective on GGT as an important virulence factor and a promising target in the management of H. pylori-associated gastric diseases.

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.

γ-glutamyl transpeptidase 1 specifically suppresses green-light avoidance via GABAA receptors in Drosophila.

Drosophila larvae innately show light avoidance behavior. Compared with robust blue-light avoidance, larvae exhibit relatively weaker green-light responses. In our previous screening for genes involved in larval light avoidance, compared with control w(1118) larvae, larvae with γ-glutamyl transpeptidase 1 (Ggt-1) knockdown or Ggt-1 mutation were found to exhibit higher percentage of green-light avoidance which was mediated by Rhodopsin6 (Rh6) photoreceptors. However, their responses to blue light did not change significantly. By adjusting the expression level of Ggt-1 in different tissues, we found that Ggt-1 in malpighian tubules was both necessary and sufficient for green-light avoidance. Our results showed that glutamate levels were lower in Ggt-1 null mutants compared with controls. Feeding Ggt-1 null mutants glutamate can normalize green-light avoidance, indicating that high glutamate concentrations suppressed larval green-light avoidance. However, rather than directly, glutamate affected green-light avoidance indirectly through GABA, the level of which was also lower in Ggt-1 mutants compared with controls. Mutants in glutamate decarboxylase 1, which encodes GABA synthase, and knockdown lines of the GABAA receptor, both exhibit elevated levels of green-light avoidance. Thus, our results elucidate the neurobiological mechanisms mediating green-light avoidance, which was inhibited in wild-type larvae.

Preliminary study of the level of visfatin and the relationship with insulin resistance in Chinese patients with chronic hepatitis C.

BACKGROUND: Many studies have suggested that visfatin expression is closely related to the occurrence of insulin resistance (IR), while the precise role of visfatin in the regulation of IR in chronic hepatitis C (CHC) is not clear. METHODS: We investigated fasting glucose, fasting insulin (FINS), C peptide, visfatin, visfatin mRNA, interleukin (IL)-6, tumor necrosis factor (TNF)-α, C-reactive protein (CRP) and other parameters of 315 patients with CHC and 150 control cases in China. Meanwhile we collected clinical and other laboratory data for further analysis. RESULTS: Compared with the control group, the CHC group had a significant increase in alanine aminotransferase (ALT), aspartate aminotransferase (AST), the AST to platelet ratio index (APRI), ratio of AST to ALT (AAR), gammaglutamyl trans-peptidase, IL-6, TNF-α, visfatin, visfatin mRNA, FINS, fasting C peptide, and IR index. The visfatin, visfatin mRNA, insulin, IR index, Homaß cell function index (HBCI), and fasting ß-cell function index (FBCI) of the subjects with high body mass index (BMI) from the CHC sub-group were significantly higher than the normal BMI sub-group of CHC patients. We found a positive correlation between visfatin, visfatin mRNA and BMI, IL-6, TNF-α, and IR index. CONCLUSION: Our data suggest that visfatin may be related to IR in Chinese CHC patients.

Evidence for conserved function of γ-glutamyltranspeptidase in Helicobacter genus.

The confounding consequences of Helicobacter bilis infection in experimental mice populations are well recognized, but the role of this bacterium in human diseases is less known. Limited data are available on virulence determinants of this species. In Helicobacter pylori, γ-glutamyltranspeptidase (γGT) contributes to the colonization of the gastric mucosa and to the pathogenesis of peptic ulcer. The role of γGT in H. bilis infections remains unknown. The annotated genome sequence of H. bilis revealed two putative ggt genes and our aim was to characterize these H. bilis γGT paralogues. We performed a phylogenetic analysis to understand the evolution of Helicobacter γGTs and to predict functional activities of these two genes. In addition, both copies of H. bilis γGTs were expressed as recombinant proteins and their biochemical characteristics were analysed. Functional complementation of Esherichia coli deficient in γGT activity and deletion of γGT in H. bilis were performed. Finally, the inhibitory effect of T-cell and gastric cell proliferation by H. bilis γGT was assessed. Our results indicated that one gene is responsible for γGT activity, while the other showed no γGT activity due to lack of autoprocessing. Although both H. bilis and H. pylori γGTs exhibited a similar affinity to L-Glutamine and γ-Glutamyl-p-nitroanilide, the H. bilis γGT was significantly less active. Nevertheless, H. bilis γGT inhibited T-cell proliferation at a similar level to that observed for H. pylori. Finally, we showed a similar suppressive influence of both H. bilis and H. pylori γGTs on AGS cell proliferation mediated by an apoptosis-independent mechanism. Our data suggest a conserved function of γGT in the Helicobacter genus. Since γGT is present only in a few enterohepatic Helicobacter species, its expression appears not to be essential for colonization of the lower gastrointestinal tract, but it could provide metabolic advantages in colonization capability of different niches.

The prognostic role of gamma-glutamyltransferase activity in non-diabetic ST-elevation myocardial infarction.

In patients with acute coronary syndrome, gamma-glutamyltransferase activity (GGT) proved to be an independent predictor of the development of major adverse cardiac events at early and long terms. No data are available on GGT in ST-elevation myocardial infarction (STEMI). We assessed, in 337 consecutive STEMI patients without previously known diabetes submitted to mechanical revascularization, the prognostic role of GGT for in-Intensive Cardiac Care Unit mortality, together with the relation(s) between GGT and acute glucose dysmetabolism (admission glycemia, peak glycemia, insulin resistance as indicated by the Homeostatic Model Assessment HOMA index). At logistic regression analysis, GGT was an independent predictor for in-ICU mortality (OR 1.01 (95% CI 1.003-1.013) p = 0.002), when adjusted for BMI and for major bleedings [(OR 1.005 (95% CI 1.001-1.009) p = 0.029]. At linear regression analyses, GGT was significantly correlated with admission glycemia (r = 0.172; p = 0.002), uric acid (r = 0.146; p = 0.011), insulin (r = 0.171; p = 0.002) and age (r = -0.129; p = 0.020). We document that in STEMI patients without previously known diabetes submitted to mechanical revascularization, GGT values are an independent predictor of early mortality. The significant correlation between GGT and acute glucose dysmetabolism (as indicated by admission glycemia and insulin-resistance) can account, at least in part, for the prognostic role of GGT.

Cefalalgia cardíaca: cuando la angina es embriagadora / Cardiac cephalalgia: when angina is heady

La angina cafalalgica cardíaca es un fenómeno poco frecuente como manifestación de un evento coronario agudo. Presentamos un caso típico de ésta manifestación que se asocia a la presencia de vasospasmo coronario y flujo coronario muy lento a nivel epicárdico y miocárdico. La presencia de palpitaciones durante la cefalea advirtió a la paciente del probable origen cardíaca de sus síntomas.

Headache angina or heart headache is a rare phenomenon as a manifestation of an acute coronary event. We report a typical case of this event that is associated with the presence of coronary vasospasm and slow coronary flow on myocardial and epicardial levels. The presence of palpitations during the headache warned the patient of probable cardiac origin of their symptoms.

Gamma-glutamyl transferase: the silent partner?

Glutathione is one of the most abundant proteins in vivo involved in maintaining cellular homeostasis and is essential for the regulation of oxidant stress. Gamma-Glutamyl transferase (GGT) is the first enzyme of the gamma glutamyl cycle that regulates the antioxidant glutathione, hence it is a critical enzyme in glutathione homeostasis. Recent findings have indicated upregulation of GGT in inflammation, increasing antioxidant defence whilst potentially driving leukotriene-induced inflammation. GGT is a marker of future comorbid diseases consistent with inflammation (and oxidative stress) as a key central pathophysiological process. COPD reflects several distinct pathological phenotypes. Inflammation (and hence oxidative stress) is influenced by other factors such as bacterial colonisation and exacerbations. The increased incidence of other co-morbid conditions with systemic inflammation suggests that common pathophysiological processes are responsible. Active oxidant stress and hence the role of GGT may play a role in these processes. Future studies of systemic and local GGT function and genotypes in well characterised patients may lead to a better understanding of the processes involved and hence the development of new treatment strategies.

Helicobacter pylori gamma-glutamyltranspeptidase induces cell cycle arrest at the G1-S phase transition.

In our previous study, we showed that Helicobacter pylori gamma-glutamyltranspeptidase (GGT) is associated with H. pylori-induced apoptosis through a mitochondrial pathway. To better understand the role of GGT in apoptosis, we examined the effect of GGT on cell cycle regulation in AGS cells. To determine the effect of recombinant GGT (rGGT) on cell cycle distribution and apoptosis, rGGT-treated and untreated AGS cells were analyzed in parallel by flow cytometry using propidium iodide (PI). We found that rGGT inhibited the growth of AGS cells in a time-dependent manner, and that the pre-exposure of cells to a caspase-3 inhibitor (z-DEVD-fmk) effectively blocked GGT-induced apoptosis. Cell cycle analysis showed G1 phase arrest and apoptosis in AGS cells following rGGT treatment. The rGGT-mediated G1 phase arrest was found to be associated with down-regulation of cyclin E, cyclin A, Cdk 4, and Cdk 6, and the up-regulation of the cyclin-dependent kinase (Cdk) inhibitors p27 and p21. Our results suggest that H. pylori GGT induces cell cycle arrest at the G1-S phase transition.

Coupled amino acid deamidase-transport systems essential for Helicobacter pylori colonization.

In addition to their classical roles as carbon or nitrogen sources, amino acids can be used for bacterial virulence, colonization, or stress resistance. We found that original deamidase-transport systems impact colonization by Helicobacter pylori, a human pathogen associated with gastric pathologies, including adenocarcinoma. We demonstrated that l-asparaginase (Hp-AnsB) and gamma-glutamyltranspeptidase (Hp-gammaGT) are highly active periplasmic deamidases in H. pylori, producing ammonia and aspartate or glutamate from asparagine and glutamine, respectively. Hp-GltS was identified as a sole and specialized transporter for glutamate, while aspartate was exclusively imported by Hp-DcuA. Uptake of Gln and Asn strictly relies on indirect pathways following prior periplasmic deamidation into Glu and Asp. Hence, in H. pylori, the coupled action of periplasmic deamidases with their respective transporters enables the acquisition of Glu and Asp from Gln and Asn, respectively. These systems were active at neutral rather than acidic pH, suggesting their function near the host epithelial cells. We showed that Hp-DcuA, the fourth component of these novel deamidase-transport systems, was as crucial as Hp-gammaGT, Hp-AnsB, and Hp-GltS for animal model colonization. In conclusion, the pH-regulated coupled amino acid deamidase-uptake system represents an original optimized system that is essential for in vivo colonization of the stomach environment by H. pylori. We propose a model in which these two nonredundant systems participate in H. pylori virulence by depleting gastric or immune cells from protective amino acids such as Gln and producing toxic ammonia close to the host cells.

[Glutathione system. II. Other enzymes, thiol-disulphide metabolism, inflammation and immunity, functions].

The great significance of glutathione as a redox regulator and the reducing carrier has been established. There is a clear necessity for subdivision of an independent mitochondrial glutathione subsystem. The data on a specificity of glutathione metabolism in different organs are accumulated. The significance of glutathione system for inflammation and immunity has been proved. The investigations of glutathione system for elucidation of pathogenesis of diseases and its diagnostics are used in medicine.

Inhibition of glyoxalase I: the first low-nanomolar tight-binding inhibitors.

A series of rational modifications to the structure of known S-(N-aryl-N-hydroxycarbamoyl)glutathione-based glyoxalase I inhibitors culminated in the discovery of the first single-digit nanomolar inhibitor. This study makes available key information about possible means to address the issues of metabolic instability, low potency, and synthetic complexicity that have plagued the area of glyoxalase I inhibition. Knowledge garnered from this study has implications in the design of inhibitors with higher conformational definition and lower peptidic character.

[Gamma-glytamiltransferase activity and cardiovascular diseases (ischemic heart disease and cerebral stroke)].

PURPOSE: To investigate association between gamma-glytamiltransferase levels and the development of CVD. The data were taken from materials of the epidemiological study " Determinants of cardiovascular disease in Eastern Europe " , the HAPPIE project. We investigated representative samples from non-organized population of men and women 45 - 69 years old living in Novosibirsk - 9361 subjects (4275 men and 5086 women). The program of study included: questionnaire of previous CVD, smoking status and alcohol consumption; two blood pressure measurements; anthropometry, biochemical analysis (gamma-glytamiltransferase, total cholesterol, HDL cholesterol, and triglycerides) and rest ECG. Among all subjects we distinguished three groups: first - patients with diagnosed ischemic heart disease (angina pectoris or myocardial infarction) and without previous cerebral stroke; second - patients with previous cerebral stroke (without ischemic heart disease); third - patients without previous ischemic heart disease and cerebral stroke (control group). We revealed reliable data on sex-dependent difference of gamma-glytamiltransferase activity: men have higher gamma-glytamiltransferase activity compared with women in all age groups. Subjects who didn t take alcoholic drinks during the last year have noticeably lower gamma-glytamiltransferase level than those who took alcoholic drinks during that period. Gamma-glytamiltransferase activity was higher both in men and women in group with ischemic heart disease, than in control group. We did not reveal difference in gamma-glytamiltransferase activity between groups with cerebral stroke and control group. The similar patterns were revealed in subjects who didn't take alcoholic drinks during the last year.

Cisplatin nephrotoxicity is mediated by gamma glutamyltranspeptidase, not via a C-S lyase governed biotransformation pathway.

Cisplatin exhibits dose-limiting nephrotoxicity in rodents and man. This study investigates the mechanism of cisplatin nephrotoxicity in vivo and in an in vitro model system. Nephrotoxicity was induced in rats (6 mg/kg cisplatin i.p.) and mice (10 mg/kg cisplatin i.p.). Cisplatin administration significantly elevated blood urea nitrogen (BUN) and serum creatinine in male Sprague Dawley rats day 5 post-treatment (BUN Delta+28+/-5 micromol/ml; serum creatinine Delta+108+/-4 nmol/ml, P<0.05) and in male C57BL6 mice day 4 post-treatment (BUN Delta+21+/-4 micromol/ml; serum creatinine Delta+81+/-5 nmol/ml, P<0.05). Nephrotoxicity was confirmed by histological analysis that revealed significant damage to the proximal tubules of cisplatin- versus saline vehicle-treated animals. Inhibition of gamma glutamyltranspeptidase prevented cisplatin nephrotoxicity in Sprague Dawley rats (day 5 BUN Delta+1+/-2 micromol/ml; serum creatinine Delta+8+/-4 nmol/ml) and C57BL6 mice (day 4 BUN Delta+1+/-0.8 micromol/ml; serum creatinine Delta-1+/-2 nmol/ml), but not cellular toxicity in rat proximal tubular (RPT) or human proximal tubular (HPT) cultures. Inhibition of aminopeptidase N (AP-N) or renal dipeptidase (RDP) in male Sprague Dawley rats, or in RPT and HPT cell cultures, did not reduce cisplatin toxicity. In contrast to published findings inhibition of C-S lyase did not prevent the nephrotoxicity of cisplatin in vivo or cellular toxicity in vitro. These data demonstrate that the biotransformation enzymes AP-N, RDP and C-S lyase are not implicated in the metabolism of cisplatin to a nephrotoxic metabolite as has been previously hypothesised. Instead, our data demonstrate that gamma glutamyltranspeptidase is a key enzyme involved in mediating cisplatin nephrotoxicity, which potentially acts to cleave cisplatin-GSH conjugates to a toxic metabolite.

Association of gamma-glutamyltransferase and risk of cancer incidence in men: a prospective study.

Although several epidemiologic studies have shown that gamma-glutamyltransferase (GGT) is independently associated with cardiovascular disease and all-cause mortality, its relationship with cancer incidence remains widely unexplored. In several experimental models, the ability of cellular GGT to modulate crucial redox-sensitive functions has been established, and it thus may play a role in tumor progression, as has been repeatedly suggested. We prospectively investigated the association between GGT and risk of overall and site-specific cancer incidence in a large population-based cohort of 79,279 healthy Austrian men with serial GGT measurements. Median follow-up was 12.5 years. Adjusted Cox proportional hazards models were calculated to evaluate GGT as an independent predictor for cancer incidence, and nonparametric regression splines were fitted to flexibly capture the dose-response relationship. Elevated GGT significantly increased overall cancer risk, showing a clear dose-response relationship (P for GGT log-unit increase < 0.0001; P for trend < 0.0001). In comparison with the reference GGT concentration (25 units/L), we found adjusted relative risks (95% confidence intervals) equalling 1.19 (1.15-1.22) for GGT concentrations of 60 units/L, 1.32 (1.28-1.36) for 100 units/L, 1.67 (1.60-1.75) for 200 units/L, and 2.30 (2.14-2.47) for 400 units/L. In cancer site-specific models, GGT was significantly associated with malignant neoplasms of digestive organs, the respiratory system/intrathoracic organs, and urinary organs (all P < 0.0001). Age of participants significantly modified the association of GGT and cancer risk (P < 0.001), revealing markedly stronger associations in participants ages