Marina Bortolami

Helicobacter pylori, inflammation, oxidative damage and gastric cancer : a morphological, biological and molecular pathway

Gastric carcinogenesis is a complex, multistep and multifactorial event, characterized by progressive cyto-histological dedifferentiation, in which the role of Helicobacter pylori infection has been established. Among the pathways relevant to gastric carcinogenesis and correlated with H. pylori infection, it has been demonstrated that the production of reactive oxygen species, with damage to the DNA, may be quite important. Oxidative damage, alone and/or in combination with exogenous and endogenous factors, induces several molecular changes. The assumption is that, in precancerous lesions, these molecular changes belong to the same biological spectrum as their invasive counterpart. The molecular profile of these preneoplastic lesions is heterogeneous, however, and there are still no molecular markers enabling the distinction between atypical hyperplastic lesions and low-grade noninvasive neoplasia (NiN) or between high-grade NiN and early invasive neoplasia. Indeed, within the spectrum of morphological changes characterizing this multistep evolution, dysplasia (NiN) is the lesion coming closest to the development of invasive adenocarcinoma. Several of the genetic and epigenetic alterations reported in gastric precancerous lesions affect DNA repair system genes, tumor suppressor genes, oncogenes, cell cycle regulators, growth factors, and adhesion molecules. Although we await reliable molecular markers, it is best to monitor patients harboring NiN closely with endoscopy and extensive bioptic sampling, and to eradicate any H. pylori to prevent the accumulation of oxidative DNA damage and its consequent progression. The growing body of evidence of the regression of precancerous changes and the high prevalence of superficial gastric carcinoma demonstrated in long-term follow-up studies on NiN make this approach mandatory.

Hepatitis C virus: from oxygen free radicals to hepatocellular carcinoma

Summary.  Epidemiological evidence clearly identifies chronic infection with hepatitis C virus (HCV) as a major risk factor for the development of hepatocellular carcinoma (HCC). Among the mechanisms that have been implicated in the pro‐carcinogenic effect of HCV infection, an increased production of reactive oxygen species in the liver seems to have a major pathogenetic role in leading from chronic inflammation to cancer. Recent data have also demonstrated that HCV is capable of inducing this active production of free radicals per se, not just through inflammation, a feature peculiar to this virus and the specific activity of its core protein. This paper provides an overview of the inter‐relationships between HCV, liver damage, free radical production and HCC, describing at least in part the complex network involving DNA oxidative damage, cytokine synthesis, proto‐oncogene activation and oestrogen receptor expression, that may all be deeply involved in liver carcinogenesis.

Oxidative DNA damage in gastric cancer : cagA status and OGG1 gene polymorphism

Oxidative DNA damage is thought to play an important part in the pathogenesis of H. pylori‐induced mucosal damage. 8‐OHdG is a sensitive marker of DNA oxidation and is repaired by a polymorphic glycosylase (OGG1) more effectively than by OGG1‐Cys326. The aims of this study were to ascertain the respective roles of H. pylori, cagA status and OGG1 polymorphism in determining 8‐OHdG levels in benign and premalignant stomach diseases and in gastric cancer (GC). The study involved 50 GC patients (for whom both neoplastic tissue and surrounding mucosa were available), 35 with intestinal metaplasia and atrophy (IMA) and 43 controls. H. pylori and cagA status were determined by histology and polymerase chain reaction for urease and cagA. 8‐OHdG was assayed using HPLC with an electrochemical detector (HPLC‐ED). The OGG1 1245C→G transversion was identified using RFLP analyses. 8‐OHdG levels were significantly higher in GC, with no differences in relation to H. pylori or cagA status. OGG1 polymorphism was documented in 34% of GC (15 Ser/Cys, 2 Cys/Cys). OGG1 1245C→G polymorphism was detected in 54% of IMA patients, but only 16% of controls (p = 0.0004) and coincided with significantly higher 8‐OHdG levels. In the multivariate analysis, 8‐OHdG levels were predicted by histotype and OGG1 status. OGG1 1245C→G polymorphism was common in both GC and IMA, but very rare in controls, and correlated more closely with 8‐OHdG levels than do H. pylori infection or cagA status.

Fas / FasL system, IL‐1β expression and apoptosis in chronic HBV and HCV liver disease

Summary.  The Fas / Fas‐ligand (FasL) system is an important death signal pathway in the liver. An enhanced local inflammatory response prompted by FasL expression, which contributes to neutrophil recruitment and interleukin‐1 beta (IL‐1β) release, seems to be crucial to chronic liver damage, persistence of viral infections, and probably initiation and / or promotion of HCC. In order to evaluate the expression of Fas, FasL, and IL‐1β in different stages of human liver disease and to determine whether hepatitis B virus (HBV) and hepatitis C virus (HCV) infections modulate their expression, also in relation to apoptosis, we examined 87 liver samples obtained from patients with: chronic hepatitis (CH) (n.42), cirrhosis (n.9) and hepatocellular carcinoma (HCC) (n.16) and corresponding peritumoural tissues (n.16); histologically‐normal liver (n.4) as controls. Fas, FasL and IL‐1β mRNA were quantified using reverse transcriptase‐polymerase chain reaction. The apoptotic index was evaluated by TUNEL analysis. Our data showed a progressive Fas / FasL increase from CH to cirrhosis followed by a decline from the latter to HCC. In histological sections apoptosis was detected in HCC. A significant difference emerged between HCV and HBV‐related disease for IL‐1β expression only in CH. A significant positive correlation between IL‐1β and FasL in HCV‐related disease (P = 0.014) and an inverse correlation between IL‐1β and Fas in HBV‐related disease (P = 0.021) were observed. The different pattern of IL‐1β, Fas and FasL expression found in HCV‐ and HBV‐mediated liver disease, points to a different modulation of immune response B and C virus induced, while the decline in Fas / FasL expression in HCC may be related to defence mechanisms adopted by HCC cells against the immune system.

Oxidative Stress and Inducible Nitric Oxide Synthase Induction in Carcinogenesis

Background: Chronic inflammation is linked to an increased risk of cancer. The molecular mechanisms underlying this correlation have been long investigated and it is well known that the inflammatory cells recruited in the inflamed tissues release chemical mediators, in particular reactive oxygen species (ROS). With respect to digestive systems, ROS have been implicated in a number of pathologies, including Helicobacter pylori-related gastritis, Barrett’s esophagus, inflammatory disease of the lower gastrointestinal tract, alcoholic liver disease and several other types of toxic and virus-mediated liver injury. ROS levels within cells and tissues are controlled by numerous antioxidant defense mechanisms, but in inflammation, ROS overproduction exceeds defenses and damage intracellular macromolecules, including nucleic acids, with formation of potentially mutagenic and carcinogenic DNA adducts. Aims: This paper summarizes our own experience investigating the link between inflammation, ROS production and oxidative DNA damage as well as the impact of the above events on cytokine and growth factor release, oncogene activation, telomere instability and microRNA in H. pylori-related gastritis, Barrett’s esophagus and, in particular, hepatitis C virus-related liver disease. The paper also describes, at least in part, the complex scenario involving nitric oxide production and its impact in some gastrointestinal diseases, as well as a number of other molecular and biochemical changes related to ROS production and inflammation. Conclusions: The paper falls obviously short of being an exhaustive summary of our understanding, but the data reported are intended as a stimulus to broaden the knowledge on the topic, also in view of the possible therapeutic implications of any advance obtained.

Autophagy and apoptosis-related genes in chronic liver disease and hepatocellular carcinoma

BackgroundDysregulation of autophagy is important in the pathogenesis of many diseases, including cancer. Several aspects of the biological role of autophagy are however still unclear and the relationship between apoptosis and autophagy, particularly in the liver has yet to be thoroughly explored. In this study we evaluated the expression of Beclin 1 (one of the main autophagocytic agents, which bridges autophagy, apoptosis and both differentiation), and both pro- (Bad, Bax) and anti-apoptotic (Bcl-2, Bcl-xL) factors in liver samples from patients with different stages of liver disease.MethodsThe study concerned 93 patients from 49 cases of chronic hepatitis (CH) (30 HCV and 19 HBV-related), 13 of cirrhosis (CIRR) (10 HCV and 3 HBV-related), 21 of hepatocellular carcinoma (both HCC and peritumoral tissues [PHCC]), and 10 controls (CONTR). Real-time PCR and Western blotting were used to measure mRNA and protein expression levels.ResultsBeclin 1 mRNA levels were lower in HCC than in CH (P = 0.010) or CIRR (P = 0.011), and so were the Bcl-xL transcripts (P < 0.0001). Bad mRNA levels were higher in CH and CIRR than in CONTR, while Bax transcripts were increased in all tissues (P = 0.036). PHCC expressed the highest Bcl-2 mRNA levels. HBV-related CH tissues showed significantly higher Bcl-xL and Bad mRNA levels than HCV-related CH (P = 0.003 and P = 0.016, respectively).ConclusionsHigh Beclin 1, Bcl-xL and Bad levels in CH and CIRR tissues suggest an interaction between autophagy and apoptosis in the early and intermediate stages of viral hepatitis. In HCC these processes seem to be downregulated, probably enabling the survival and growth of neoplastic hepatocytes.

Estrogens receptors and oxidative damage in the liver

There is considerable evidence that reactive oxygen species (ROS) have a causative role in chronic hepatic injury and cancer development via direct and indirect mechanisms. Estrogens produce free oxygen radicals through redox cycling and affect cell proliferation, also in the liver. We are presently involved in evaluating the possible relationship between estrogens receptor expression, type of receptor, oxidative DNA damage and c-myc in chronic liver disease. The data on DNA adducts, c-myc mRNA and variant estrogen receptor in patients with HCV- or HBV-related chronic liver disease are suggesting that those positive for variant liver estrogen receptor present higher genomic oxidative damage, as reflected in 8-OHdG levels. We are also observing that patients with chronic hepatitis and cirrhosis, when positive for variant estrogen receptor, present higher c-myc m-RNA expression, a factor reportedly associated with increased genomic instability, augmented cytoproliferation and carcinogenesis. Our own and other authors data are shedding new light on estrogen pathophysiology, liver damage and hepatic cancer.

Mucosal immune environment in colonic carcinogenesis: CD80 up-regulation in colonic dysplasia in ulcerative colitis.

BACKGROUND In patients with ulcerative colitis (UC) the inconsistency between the rate of dysplasia and actual cancer incidence suggests the presence of an immunosurveillance mechanism. The aim of our study was to analyse the expression of CD80 and CD86 during the different stages of UC-associated and in non-inflammatory carcinogenesis. PATIENTS AND METHODS Sixty-two patients affected with UC, UC with colonic dysplasia, UC and cancer, colonic adenoma, or colonic cancer and 11 healthy subjects were enrolled in our study. Tissue samples were taken from surgical specimens during colonic resection or during colonoscopy. Mucosal mRNA expression of CD80 and CD86 was quantified with real time polymerase chain reaction (RT-PCR). CD80, CD86 and p53 expressions and lamina propria mononuclear cell populations (CD3, CD20 and CD68) were analysed by immunohistochemistry. Mucosal levels of IL-1β, IL-2 and IFN-γ were measured with immunometric assays. RESULTS Among UC patients, CD80 protein expression was higher in those with dysplasia (p=0.017). In non-inflammatory carcinogenesis pathway CD80 protein and mRNA expressions were lower compared to the corresponding steps in the UC pathway. CD80 expression was directly correlated with the lamina propria mononuclear cell populations (T and B lymphocytes and monocytes). CD80 protein, but not CD80 mRNA, expression was significantly and directly correlated with IL-2 expression. CONCLUSION CD80 resulted to be up-regulated in UC with dysplasia, while it was down-regulated in cancer. CD80 mucosal levels correlate with lamina propria T-cell and with IL-2 expression suggesting that it may elicit an active role in the immunosurveillance mechanism.

Mucosal immune environment in colonic carcinogenesis: CD80 expression is associated to oxidative DNA damage and TLR4-NFκB signalling.

BACKGROUND CD80 has been thought to play an active role in immunosurveillance as it has been found to be up-regulated in ulcerative colitis (UC) patients with dysplasia. The aim of the present study was to analyse early events in UC-related and non-inflammatory carcinogenesis with reference to CD80 expression to clarify what stimuli are involved in its up-regulation in these patients. PATIENTS AND METHODS Sixty-two patients affected with UC, UC with dysplasia, UC and cancer, colonic adenoma, or colonic cancer and 11 healthy subjects were enroled in our study. Tissue samples were taken from surgical specimens during colonic resection or during colonoscopy. Mucosal mRNA expression of Toll-like receptor-4 (TLR4) and nuclear factor-kappaB (NF-κB) was quantified with Real Time RT-PCR. TLR4, β-catenin and p53 expressions were analysed by immunohistochemistry. Mucosal levels of activated NF-κB were measured with immunometric assays while 8-Hydroxydeoxyguanosine (8-OHdG) levels were quantified by high-performance liquid chromatography with electrochemical detection (HPLC-ED). Non-parametric tests were used for statistical analysis. RESULTS 8-OHdG mucosal levels were higher in the patients with UC + dysplasia with respect to those in the patients with UC only (p=0.03). CD80 mRNA mucosal levels were directly correlated with 8-OHdG mucosal levels (τ=0.26, p=0.04), TLR4 protein expression (τ=0.45, p<0.01) and NF-κB mRNA expression and activity (τ=0.24, p=0.02; τ=0.34, p=0.02, respectively). CD80 protein expression, instead, was directly correlated with 8-OHdG mucosal levels (τ=0.19, p=0.05) and inversely correlated with TLR4 mRNA expression (τ=-0.25, p=0.03). CONCLUSION Oxidative DNA damage peaked in UC-related dysplasia and was found to be directly correlated to CD80 expression. The direct correlation between TLR4 protein expression and CD80 mRNA and the indirect correlation between CD80 protein and TLR4 mRNA expressions give substance to the hypothesis that they play a role in immunosurveillance. No significant correlations between CD80 expression and p53 and β-catenin accumulation during oncogenesis were, instead, observed.

Bax Inhibitor-1 down-regulation in the progression of chronic liver diseases

BackgroundBax inhibitor-1 (BI-1) is an evolutionary conserved endoplasmic reticulum protein that, when overexpressed in mammalian cells, suppresses the apoptosis induced by Bax, a pro-apoptotic member of the Bcl-2 family. The aims of this study were: (1) to clarify the role of intrinsic anti- and pro-apoptotic mediators, evaluating Bax and BI-1 mRNA and protein expressions in liver tissues from patients with different degrees of liver damage; (2) to determine whether HCV and HBV infections modulate said expression.MethodsWe examined 62 patients: 39 with chronic hepatitis (CH) (31 HCV-related and 8 HBV-related); 7 with cirrhosis (6 HCV-related and 1 HBV-related); 13 with hepatocellular carcinoma (HCC) [7 in viral cirrhosis (6 HCV- and 1 HBV-related), 6 in non-viral cirrhosis]; and 3 controls. Bax and BI-1 mRNAs were quantified by real-time PCR, and BI-1 protein expression by Western blot.ResultsCH tissues expressed significantly higher BI-1 mRNA levels than cirrhotic tissues surrounding HCC (P < 0.0001) or HCC (P < 0.0001). Significantly higher Bax transcripts were observed in HCV-genotype-1-related than in HCV-genotype-3-related CH (P = 0.033). A positive correlation emerged between BI-1 and Bax transcripts in CH tissues, even when HCV-related CH and HCV-genotype-1-related CH were considered alone (P = 0.0007, P = 0.0005 and P = 0.0017, respectively).ConclusionsBI-1 expression is down-regulated as liver damage progresses. The high BI-1 mRNAs levels observed in early liver disease may protect virus-infected cells against apoptosis, while their progressive downregulation may facilitate hepatocellular carcinogenesis. HCV genotype seems to have a relevant role in Bax transcript expression.