Smoking-related increase of O(6)-methylguanine-DNA methyltransferase expression in squamous cell carcinoma of the esophagus

Epigenetic Biomarkers Screening of Non-Coding RNA and DNA Methylation Based on Peripheral Blood Monocytes in Smokers

This study aims to use bioinformatics methods to determine the epigenetic changes in microRNA expression and DNA methylation caused by cigarette smoking. The data of mRNA, miRNA expression, and methylation microarray were obtained from the GEO database to filter differentially expressed genes (DEGs), differentially expressed miRNAs (DEMs), and methylated CpG probes (DMPs) through the limma package. The R clusterProfile package was used for functional annotation and enrichment analysis. The protein-protein interaction (PPI) network was constructed by the String database and visualized in Cytoscape software. Starbase database was employed to predict lncRNA and CirRNA based on the sequence of miRNA, and to establish a regulatory network of ceRNA. By overlapping DEG and DEM, 107 down-miRNA-targeted up-regulated genes and 65 up-miRNA-target down-regulated genes were obtained, which were mainly enriched in autophagy signaling pathways and protein ubiquitination pathways, respectively. In addition, 324 genes with low methylation and high expression and 204 genes with high methylation and low expression were respectively related to the degeneration of the nervous system and the function of the cardiovascular system. Interestingly, 43 genes were up-regulated under the dual regulation of reduced miRNA and hypomethylation, while 14 genes were down-regulated under the dual regulation of increased miRNA and hypermethylation. Ten chemicals have been identified as putative therapeutic agents for pathological conditions caused by smoking. In addition, among these genes, HSPA4, GRB2, PRKCA, and BCL2L1 could play a fundamental role in related diseases caused by smoking and may be used as the biomarkers for precise diagnosis and targets for future therapies of smoking-related diseases.

Associations among smoking, MGMT hypermethylation, TP53-mutations, and relapse in head and neck squamous cell carcinoma

Background

Epigenetic silencing of the O⁶-methylguanine-DNA methyltransferase (MGMT) DNA repair enzyme via promoter hypermethylation (hmMGMT) may increase mutations in the TP53 oncosuppressor gene and contribute to carcinogenesis. The effects of smoking, which is a risk factor for head and neck squamous cell carcinoma (HNSCC), were investigated to determine whether they up- or down-regulate hmMGMT. Additionally, the impact of hmMGMT and disruptive TP53-mutations on relapse was investigated in patients with HNSCC.

Methods

This study included 164 patients with HNSCC who were negative for both p16 protein expression and human papilloma virus infection. The association of smoking and hmMGMT was investigated using multiple logistic regression analysis. Competing risk regression was used to evaluate the effects of hmMGMT and TP53-mutations in exon 2 to 11 on relapse of HNSCC.

Results

hmMGMT was observed in 84% of the 164 patients. TP53-mutations, specifically, G:C>A:T transition, were more frequent in patients with hmMGMT (32%) than in those without hmMGMT (8%). The frequency of disruptive TP53-mutations was not significantly different between groups. Compared with nonsmoking, heavy smoking of 20 pack-years or more was significantly associated with decreased hmMGMT (adjusted odds ratio, 0.08; 95% CI, 0.01 to 0.56; P = 0.01). Patients who had both hmMGMT and disruptive TP53-mutations showed a significantly higher relapse rate than all other patients (subdistribution hazard ratio, 1.77; 95% CI, 1.07 to 2.92; P = 0.026).

Conclusions

It was found that hmMGMT was suppressed by heavy smoking, and hmMGMT combined with disruptive TP53-mutations may indicate a poor prognosis in patients with HNSCC.

Hyperinsulinemia Promotes Esophageal Cancer Development in a Surgically-Induced Duodeno-Esophageal Reflux Murine Model

Hyperinsulinemia could have a role in the growing incidence of esophageal adenocarcinoma (EAC) and its pre-cancerous lesion, Barrett's Esophagus, a possible consequence of Gastro-Esophageal Reflux Disease. Obesity is known to mediate esophageal carcinogenesis through different mechanisms including insulin-resistance leading to hyperinsulinemia, which may mediate cancer progression via the insulin/insulin-like growth factor axis. We used the hyperinsulinemic non-obese FVB/N (Friend leukemia virus B strain) MKR (muscle (M)-IGF1R-lysine (K)-arginine (R) mouse model to evaluate the exclusive role of hyperinsulinemia in the pathogenesis of EAC related to duodeno-esophageal reflux. FVB/N wild-type (WT) and MKR mice underwent jejunum-esophageal anastomosis side-to end with the exclusion of the stomach. Thirty weeks after surgery, the esophagus was processed for histological, immunological and insulin/Insulin-like growth factor 1 (IGF1) signal transduction analyses. Most of the WT mice (63.1%) developed dysplasia, whereas most of the MKR mice (74.3%) developed squamous cell and adenosquamous carcinomas, both expressing Human Epidermal growth factor receptor 2 (HER2). Hyperinsulinemia significantly increased esophageal cancer incidence in the presence of duodenal-reflux. Insulin receptor (IR) and IGF1 receptor (IGF1R) were overexpressed in the hyperinsulinemic condition. IGF1R, through ERK1/2 mitogenic pattern activation, seems to be involved in cancer onset. Hyperinsulinemia-induced IGF1R and HER2 up-regulation could also increase the possibility of forming of IGF1R/HER2 heterodimers to support cell growth/proliferation/progression in esophageal carcinogenesis.

Heterogeneous impact of alcohol consumption according to treatment method on survival in head and neck cancer: A prospective study

Alcohol consumption is an established risk factor, and also a potential prognostic factor, for squamous cell carcinoma of the head and neck (HNSCC). However, little is known about whether the prognostic impact of alcohol consumption differs by treatment method. We evaluated the association between alcohol drinking and survival by treatment method to the primary site in 427 patients with HNSCC treated between 2005 and 2013 at Aichi Cancer Center Central Hospital (Nagoya, Japan). The impact of alcohol on prognosis was measured by multivariable Cox regression analysis adjusted for established prognostic factors. Among all HNSCC patients, the overall survival rate was significantly poorer with increased levels of alcohol consumption in multivariable analysis (trend P = 0.038). Stratification by treatment method and primary site revealed that the impact of drinking was heterogeneous. Among laryngopharyngeal cancer (laryngeal, oropharyngeal, and hypopharyngeal cancer) patients receiving radiotherapy (n = 141), a significant dose-response relationship was observed (trend P = 0.034). In contrast, among laryngopharyngeal cancer patients treated with surgery (n = 80), no obvious impact of alcohol was observed. This heterogeneity in the impact of alcohol between surgery and radiotherapy was significant (for interaction, P = 0.048). Furthermore, among patients with oral cavity cancer treated by surgery, a significant impact of drinking on survival was seen with tongue cancer, but not with non-tongue oral cancer. We observed a significant inverse association between alcohol drinking and prognosis among HNSCC patients, and its impact was heterogeneous by treatment method and primary site.

Combined heavy smoking and drinking predicts overall but not disease-free survival after curative resection of locoregional esophageal squamous cell carcinoma

INTRODUCTION

The prognostic impact of smoking and drinking on esophageal squamous cell carcinoma (ESCC) was scarcely discussed. We investigated the prognostic value of smoking and drinking and their relationships with clinicopathological characteristics in a large cohort of patients with locoregional ESCC.

PATIENTS AND METHODS

We retrospectively analyzed 488 patients who underwent curative treatment at a single institution between January 2007 and December 2008. A chi-square test was used to evaluate the relationships between smoking and drinking and clinicopathological variables, the Kaplan-Meier method was used for 5-year overall survival (OS) and disease-free survival, and Cox proportional hazards models were applied for univariate and multivariate analyses of variables with respect to OS and disease-free survival.

RESULTS

Heavy smokers were more likely to have advanced Tumor-Node-Metastases (TNM) stage and higher neutrophil/lymphocyte ratio at diagnosis (P<0.05). Drinkers were more likely to have advanced TNM stage, to present with a larger tumor, and to undergo multidisciplinary treatment (P<0.05). For patients who used neither heavy tobacco nor alcohol, used either tobacco or alcohol, and used both, the 5-year OS rates and OS times were 57.4%, 46.4%, and 39.1% (P<0.05) and not reached, 55.2 months, and 41.2 months (P<0.05), respectively. On multivariate analysis, patients who both heavily smoked and drank had 1.392 times the risk of dying during follow-up compared with neither-users (95% CI =1.020-1.901, P=0.037).

CONCLUSION

We identified that combined heavy smoking and drinking might predict poor prognosis in ESCC patients.

Abnormal MGMT promoter methylation may contribute to the risk of esophageal cancer: a meta-analysis of cohort studies

This meta-analysis was conducted aiming to evaluate the relationship between abnormal O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation and the risk of esophageal cancer (EC). A range of electronic databases was searched: Web of Science (1945 ~ 2013), the Cochrane Library Database (Issue 12, 2013), MEDLINE (1966 ~ 2013), EMBASE (1980 ~ 2013), CINAHL (1982 ~ 2013), and the Chinese Biomedical Database (CBM) (1982 ~ 2013) without language restrictions. Meta-analysis was performed with the use of the STATA 12.0 software. In the present meta-analysis, 9 clinical cohort studies with a total of 861 EC patients were included. The pooled results revealed that the frequency of MGMT promoter methylation in cancer tissues was significantly higher than in adjacent and normal tissues (cancer tissues vs adjacent tissues, odds ratio (OR) = 6.73, 95 % confidence intervals (95 % CI) 4.75 ~ 9.55, P < 0.001; cancer tissues vs normal tissues, OR = 13.68, 95 % CI 9.47 ~ 19.75, P < 0.001, respectively). Subgroup analyses by pathological type, ethnicity, and sample size suggested that abnormal MGMT promoter methylation also exhibited a higher frequency in all these subgroups (all P < 0.05). Our findings provide empirical evidence that abnormal MGMT promoter methylation may contribute to the risk of EC. Thus, detection of MGMT promoter methylation may be utilized as a valuable diagnostic marker for EC.

Predictors of pathological complete response to neoadjuvant chemoradiotherapy for esophageal squamous cell carcinoma

BACKGROUNDS

In this study, we evaluated the factors associated with a pathologic complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) for esophageal squamous cell carcinoma (ESCC).

METHODS

Pre-nCRT parameters in ESCC patients treated between 1999 and 2006 were analyzed to identify predictors of pCR. All patients received 5-fluorouracil/cisplatin-based chemotherapy and external beam radiation followed by scheduled esophagectomy. Variables were analyzed using univariate and multivariate analyses with pCR as the dependent variable. Estimated pCR rate was calculated with a regression model.

RESULTS

Fifty-nine (20.9%) of 282 patients achieved pCR. Univariate analysis identified four patient factors (age, smoking status, drinking history and hypertension), one pre-nCRT parameter (tumor length) as significant predictors of pCR (all P <0.05). On multivariate analysis, tumor length ≤3 cm (favorable, odds ratio (OR): 4.85, P = 0.001), patient age >55 years (favorable, OR: 1.95, P = 0.035), and being a non-smoker (favorable, OR: 3.6, P = 0.003) were independent predictors of pCR. The estimated pCR rates based on a logistic regression including those three predictors were 71%, 35 to approximately 58%, 19 to approximately 38%, and 12% for patients with 3, 2, 1 and 0 predictors, respectively.

CONCLUSION

Age, smoking habit and tumor length were important pCR predictors. These factors may be used to predict outcomes for ESCC patients receiving nCRT, to develop risk-adapted treatment strategies, and to select patients who could participate in trials on new therapies.

Oxidative DNA damage in human esophageal cancer: clinicopathological analysis of 8-hydroxydeoxyguanosine and its repair enzyme

Both internal and external oxidative stresses act on DNA and can induce carcinogenesis. 8-hydroxydeoxyguanosine (8-OHdG) is an indicator of oxidative stress and it leads to transversion mutations and carcinogenesis. 8-OHdG is excision-repaired by 8-OHdG DNA glycosylase (OGG1). The purpose of this study is to clarify the effect of oxidative DNA damage and repair enzymes on esophageal carcinogenesis. The levels of 8-OHdG and OGG1 were immunohistochemically evaluated in resected specimens, including squamous cell carcinoma (SCC) in 97 patients with esophageal cancer. Higher levels of 8-OHdG in normal esophageal epithelium were associated with a higher smoking index (P = 0.0464). The 8-OHdG level was higher in cancerous areas than in normal epithelia (P = 0.0061), whereas OGG1 expression was weaker in cancerous areas than in normal epithelia (P < 0.0001). An increase of OGG1 expression in normal epithelium was observed as 8-OHdG levels increased (P = 0.0011). However, this correlation was not observed in cancerous areas. High OGG1 expression in the cytoplasm was related to deeper tumors (P = 0.0023), node metastasis (P = 0.0065) and stage (P = 0.0019). Oxidative DNA damage, which is attributable to smoking as well as disturbances in DNA repair systems, appears to be closely related to esophageal carcinogenesis and its progression.

Continuous taurocholic acid exposure promotes esophageal squamous cell carcinoma progression due to reduced cell loss resulting from enhanced vascular development

BACKGROUND

Refluxogenic effects of smoking and alcohol abuse may be related to the risk of esophageal squamous cell carcinoma (ESCC). The present study attempts to clarify the effects of continuous taurocholic acid (TCA) exposure, which is neither mutagenic nor genotoxic, on ESCC progression.

METHODS

A squamous carcinoma cell line (ESCC-DR) was established from a tumor induced in a rat model of gastroduodenal reflux. ESCC-DR cells were incubated with 2 mM TCA for ≥2 months. The effects of continuous TCA exposure were evaluated in vitro on cell morphology, growth, and invasion and in vivo on xenograft tumor growth in nude mice. Moreover, the mean level of secreted transforming growth factor (TGF)-β1 and vascular endothelial growth factor (VEGF) proteins in cell culture supernatants and mRNA synthesis of TGF-β1 and VEGF-A of ESCC cells were measured. The angiogenic potential was further examined by a migration assay using human umbilical vein endothelial cells (HUVECs).

RESULTS

Continuous TCA exposure induced marked formation of filopodia in vitro. Expression levels of angiogenic factors were significantly higher in the cells treated with TCA than in control cells. Tumor xenografts derived from cells pre-exposed to TCA were larger and more vascularized than those derived from control cells. In addition, TCA exposure increased HUVEC migration.

CONCLUSION

Continuous TCA exposure enhanced ESCC progression due to reduced cell loss in vivo. Cell loss was inhibited by TCA-induced vascular endothelial cell migration, which was mediated by TGF-β1 and VEGF-A released from ESCC cells.

The expression of O(6) -methylguanine-DNA methyltransferase in human oral keratinocytes stimulated with arecoline

BACKGROUND

O(6) -methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that can protect cells from carcinogenic effects of alkylating agents by removing adducts from the O(6) position of guanine. Evidences indicated that areca quid chewing may increase the risk of oral squamous cell carcinoma (OSCC). This study was to investigate the role of MGMT expression in OSCCs and the normal oral tissues.

METHODS

Thirty-two OSCCs from areca quid chewers and ten normal oral tissue biopsy samples without areca quid chewing were analyzed by the immunohistochemistry for MGMT. Primary human oral keratinocytes (HOKs) were challenged with arecoline, the major alkaloid of areca nut, by Western blot. Nicotine, an important component of cigarette smoke, was added to find the possible regulatory mechanisms.

RESULTS

Significant association was observed between low MGMT expression and advanced clinical stage of OSCCs and lymph node metastasis (P = 0.03). MGMT expression was significantly higher in patients only chewing areca quid than patients both chewing areca quid and smoking (P = 0.028). Arecoline was found to elevate MGMT expression in a dose- and time-dependent manner. The addition of nicotine was found to enhance arecoline-induced MGMT expression.

CONCLUSION

Our results indicate that MGMT could be used clinically as a predictive marker for tumor processing, the potential for lymph node metastasis as well as advanced clinical stage. MGMT expression was significantly upregulated by arecoline in HOKs. Nicotine has a synergistic effect of arecoline-induced MGMT expression. The cigarette smoking may act synergistically in the pathogenesis of OSCC in areca quid chewers via the upregulation of MGMT.

O(6)-methylguanine-DNA methyltransferase (MGMT): impact on cancer risk in response to tobacco smoke

Tobacco, smoked, snuffed and chewed, contains powerful mutagens and carcinogens. At least three of them, N-dimethylnitrosamine, N'-nitrosonornicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, attack DNA at the O(6)-position of guanine. The resulting O(6)-alkylguanine adducts are repaired by the suicide enzyme O(6)-methylguanine-DNA methyltransferase (MGMT), which is known to protect against the mutagenic, genotoxic and carcinogenic effects of monofunctional alkylating agents. While in rat liver MGMT was shown to be subject to regulation by genotoxic stress leading to adaptive changes in its activity, in humans evidence of adaptive modulation of MGMT levels is still lacking. Several polymorphisms are known, which are suspected to impact on the risk of developing cancer. In this review we focus on three questions: (a) Has tobacco consumption by smoking or chewing an impact on MGMT expression and MGMT promoter methylation in normal and tumor tissue? (b) Is there an association between MGMT polymorphisms and cancer risk and is this risk related to smoking? (c) Does MGMT protect against tobacco-associated cancer? There are several lines of evidence for an increase of MGMT activity in the normal tissue of smokers compared to non-smokers. Furthermore, in tumors developed in smokers a tendency towards an increase of MGMT expression was found. The data points to the possibility that agents in tobacco smoke are able to trigger upregulation of MGMT in normal and tumor tissue. For MGMT promoter methylation data is conflicting. There is some evidence for an association between MGMT polymorphisms and smoking-induced cancer risk. The key question whether or not MGMT protects against tobacco smoke-induced cancer is difficult to answer since prospective studies on smokers versus non-smokers are lacking and appropriate animal studies with MGMT transgenic mice exposed to the complex mixture of tobacco smoke have not been performed, which indicates the need for further explorations.

Heavy smoking history interacts with chemoradiotherapy for esophageal cancer prognosis: a retrospective study

Smoking is a well-known risk factor for esophageal cancer. However, there are few reports that directly evaluate smoking as a prognostic factor for esophageal cancer. Moreover, scarce evidence is available on whether smoking interacts with major treatment modalities of esophageal cancer. In this study we retrospectively analyzed 364 patients with esophageal squamous cell cancer who were treated between 2001 and 2005 at our institution. Background characteristics, including smoking history, were analyzed as potential prognostic factors. Of the 363 patients, 76 patients (20.9%) were non-smokers or light smokers (non-heavy), whereas 287 patients (79.1%) were heavy smokers. The 5-year survival rate for non-heavy smokers and heavy smokers was 61.8% (95% confidence interval [CI]: 49.1-72.2) vs 44.6% (95% CI: 38.2-50.9), respectively. In a multivariate Cox model (adjusted for age, gender, performance status, alcohol consumption, histology, tumor length, International Union Against Cancer [UICC] stage, and treatment), the hazard ratio for heavy smokers in comparison with non-heavy smokers was 1.73 (95% CI: 1.12-2.68; P = 0.013). When we stratified by treatment method, heavy smoking was significantly associated with poor survival only in patients treated by chemoradiotherapy (hazard ratio, 2.43; 95% CI: 1.38-4.27; P = 0.002). More importantly, a statistically significant interaction between heavy smoking history and treatment modality was observed (P = 0.041). Our results indicated that smoking history is strongly associated with poor prognosis in patients with esophageal cancer, especially those treated by chemoradiotherapy. Further investigation is warranted to explain this different prognosis.

Initiation of malignancy by duodenal contents reflux and the role of ezrin in developing esophageal squamous cell carcinoma

Gastroesophageal reflux has recently been implicated as a causative factor in upper aerodigestive tract carcinogenesis. Esophageal squamous cell carcinomas (ESCCs) have developed in duodenal-content reflux animals without any known carcinogen present. We established a cell line, designated ESCC-DR, from a thoracic metastatic tumor in a reflux animal. To gain insight into the genomic alterations associated with duodenal content reflux-induced carcinogenesis, we first performed comparative genomic hybridization using an Agilent rat 244K array in ESCC-DR and identified many chromosomal gains and losses. Of the many genes identified, we detected an interesting ezrin amplicon that has been recently reported in human ESCC. Ezrin, which cross-links the cytoskeleton and plasma membrane, is involved in the growth and metastatic potential of cancer cells. Overexpression of ezrin protein in ESCC-DR was confirmed by Western blotting. We also compared ezrin protein expression levels and patterns in hyperplastic, dysplastic, ESCC, and metastatic sites developed in two distinct reflux models using immunohistochemistry. Immunohistochemical staining of ezrin revealed overexpression in the nucleus, and the cytoplasm as well as plasma membrane of ESCC cells. Phosphorylated ERM (ezrin, radixin, moesin) was expressed at the leading edge, or invasive front, of larger metastatic sites. Taken together, duodenal reflux has a great potential for initiating malignancy, and thus likely plays a role in development of ESCC. Ezrin probably influences the growth and invasiveness of ESCC cells, and phosphorylation is only required in metastatic behavior of tumor cells at the leading edge and invasive front.

High animal-fat intake changes the bile-acid composition of bile juice and enhances the development of Barrett's esophagus and esophageal adenocarcinoma in a rat duodenal-contents reflux model

The dietary components responsible for the development of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC) remain unclear. Wistar rats were divided into four groups based on their diet: a low soybean-oil diet, a low cow-fat diet, a high soybean-oil diet, and a high cow-fat diet. First, we evaluated the bile acid composition of the bile juice in each group without operation, using high-performance liquid chromatography. Because only high cow-fat intake induced changes in the composition of bile acids in bile juice, we then selected animals fed with a low soybean-oil diet and those with a high cow-fat diet to carry out esophago-jejunostomy for reflux of the duodenal contents, and compared sequential morphological changes between these groups up to 30 weeks after surgery. At 30 weeks after surgery, the reflux animals in the high cow-fat group showed a significantly higher incidence of BE and Barrett's dysplasia than those in the low soybean-oil group, and the incidence of EAC in the high cow-fat group was also slightly higher than that in the low soybean-oil group. High dietary animal fat changed the bile-acid composition and increased the concentration of taurine conjugates in the bile juice. These increased bile acids promoted the development of BE and Barrett's dysplasia leading to EAC.

Loss of expression of DNA repair enzyme MGMT in oral leukoplakia and early oral squamous cell carcinoma. A prognostic tool?

MGMT is a specific DNA repair enzyme that removes alkylating lesions and therefore plays an important role in maintaining normal cell physiology and genomic stability. Loss of expression of MGMT is associated with increased carcinogenic risk and sensitivity to methylating agents in different types of tumours. The expression of MGMT was immunohistochemically assessed in 12 normal oral mucosa, 38 oral leukoplakias and 33 early oral squamous cell carcinomas. The results were correlated with clinicopathological data. We found a significant loss of MGMT protein expression from leukoplakia when compared with early squamous cell carcinoma. We also observed a statistically significant relationship between smoking and the loss of MGMT protein expression. Loss of MGMT expression could be considered an early event in oral carcinogenesis with possible prognostic implications.