Kai-Feng Pan

Identification of Serum MicroRNAs as Novel Non-Invasive Biomarkers for Early Detection of Gastric Cancer

Background To investigate the potential of serum miRNAs as biomarkers for early detection of gastric cancer (GC), a population-based study was conducted in Linqu, a high-risk area of GC in China. Methodology/Principal Findings All subjects were selected from two large cohort studies. Differential miRNAs were identified in serum pools of GC and control using TaqMan low density array, and validated in individual from 82 pairs of GC and control, and 46 pairs of dysplasia and control by real-time quantitative reverse transcription-polymerase chain reaction. The temporal trends of identified serum miRNA expression were further explored in a retrospective study on 58 GC patients who had at least one pre-GC diagnosis serum sample based on the long-term follow-up population. The miRNA profiling results demonstrated that 16 miRNAs were markedly upregulated in GC patients compared to controls. Further validation identified a panel of three serum miRNAs (miR-221, miR-744, and miR-376c) as potential biomarkers for GC detection, and receiver operating characteristic (ROC) curve-based risk assessment analysis revealed that this panel could distinguish GCs from controls with 82.4% sensitivity and 58.8% specificity. MiR-221 and miR-376c demonstrated significantly positive correlation with poor differentiation of GC, and miR-221 displayed higher level in dysplasia than in control. Furthermore, the retrospective study revealed an increasing trend of these three miRNA levels during GC development (P for trend<0.05), and this panel could classify serum samples collected up to 5 years ahead of clinical GC diagnosis with 79.3% overall accuracy. Conclusions/Significance These data suggest that serum miR-221, miR-376c and miR-744 have strong potential as novel non-invasive biomarkers for early detection of GC.

Efficacy of Cranberry Juice on Helicobacter pylori Infection: a Double‐Blind, Randomized Placebo‐Controlled Trial

Background.  Helicobacter pylori infection is a major cause of peptic ulcer disease and gastric cancer. This study postulated that cranberry juice would be effective in the suppression of H. pylori in an endemically infected population at high risk for gastric cancer.

DNA methylation in peripheral blood: a potential biomarker for cancer molecular epidemiology.

Aberrant DNA methylation is associated with cancer development and progression. There are several types of specimens from which DNA methylation pattern can be measured and evaluated as an indicator of disease status (from normal biological process to pathologic condition) and even of pharmacologic response to therapy. Blood-based specimens such as cell-free circulating nucleic acid and DNA extracted from leukocytes in peripheral blood may be a potential source of noninvasive cancer biomarkers. In this article, we describe the characteristics of blood-based DNA methylation from different biological sources, detection methods, and the factors affecting DNA methylation. We provide a comprehensive literature review of blood-based DNA methylation as a cancer biomarker and focus on the study of DNA methylation using peripheral blood leukocytes. Although DNA methylation patterns measured in peripheral blood have great potential to be useful and informative biomarkers of cancer risk and prognosis, large systematic and unbiased prospective studies that consider biological plausibility and data analysis issues will be needed in order to develop a clinically feasible blood-based assay.

Effects of selective COX-2 inhibitor and Helicobacter pylori eradication on precancerous gastric lesions

Objective Helicobacter pylori infection and overexpression of cyclo-oxygenase-2 (COX-2) are associated with gastric cancer and its precursors. To evaluate the effect of a selective COX-2 inhibitor alone and combined with H pylori eradication on the evolution of precancerous gastric lesions, a randomised, placebo-controlled trial was conducted in Linqu County, Shandong Province, China. Methods A total of 1024 participants aged 35–64 years with H pylori infection and advanced gastric lesions were randomly assigned in a factorial design to two interventions or placebo: anti-H pylori treatment for 7 days, and a COX-2 inhibitor (celecoxib) for 24 months. The effects of the interventions were evaluated by the regression or progression of advanced gastric lesions. Results Of the 1024 participants who received anti-H pylori treatment or placebo, 919 completed a subsequent 24-month treatment with celecoxib or placebo. The H pylori eradication rate by per-protocol analysis was 78.2%. Compared with placebo, the proportions of regression of gastric lesions significantly increased in the celecoxib treatment (52.8% vs 41.2%) and anti-H pylori treatment (59.3% vs 41.2%) group, and OR by per-protocol analysis was 1.72 (95% CI 1.07 to 2.76) for celecoxib and 2.19 (95% CI 1.32 to 3.64) for H pylori eradication. No statistically significant effect was found for H pylori eradication followed by celecoxib on the regression of advanced gastric lesions (OR 1.48, 95% CI 0.91 to 2.40). Conclusion This population-based intervention trial revealed that celecoxib treatment or H pylori eradication alone had beneficial effects on the regression of advanced gastric lesions. No favourable effects were seen for H pylori eradication followed by celecoxib treatment. Trial registration HARECCTR0500053 in accordance with WHO ICTRP requirements.

Genetic Variants of Toll-Like Receptor 2 and 5, Helicobacter Pylori Infection, and Risk of Gastric Cancer and Its Precursors in a Chinese Population

Background: Genetic polymorphisms of Toll-like receptors (TLR) may influence the outcome of Helicobacter pylori infection and play important roles in gastric carcinogenesis. To screen the genetic variants of TLR2 and TLR5, and evaluate their associations with gastric cancer (GC) and its precursors, a population-based study was conducted in Linqu County, Shandong Province, China. Methods: Genetic variants were identified by PCR-based denaturing high-performance liquid chromatography and PCR-restriction fragment length polymorphism analysis in 248 GC cases, 846 subjects with advanced gastric lesions including 350 dysplasia and 496 intestinal metaplasia, and 496 superficial gastritis/mild chronic atrophic gastritis controls. Results: Nine allelic variants each were detected within the promoter and exons of TLR2 and TLR5. Among those, TLR2 c. −196 to −174 del carriers (ins/del+del/del) showed a significantly decreased risk of GC (adjusted OR, 0.66; 95% CI: 0.48–0.90), whereas TLR5 rs5744174 C carriers (TC+CC) had an increased risk of GC (OR, 1.43; 95% CI: 1.03–1.97). Further analysis indicated an elevated risk of GC in subjects with the TLR5 rs5744174 TC+CC genotype and H. pylori infection (OR, 3.35; 95% CI: 2.13–5.26), and a significant interaction between rs5744174 and H. pylori infection was observed (OR, 2.15; 95% CI: 1.12–4.16). Conclusion: These findings suggest that TLR2 c. −196 to −174 ins > del, TLR5 rs5744174 and interaction between rs5744174 and H. pylori infection were associated with the development of GC. Impact: TLR2 and TLR5 polymorphisms may play important roles in the process of H. pylori-related gastric carcinogenesis. Cancer Epidemiol Biomarkers Prev; 20(12); 2594–602. ©2011 AACR.

Promoter methylation of p16 associated with Helicobacter pylori infection in precancerous gastric lesions: A population-based study

To investigate the relationship between p16 methylation and Helicobacter pylori infection in precancerous gastric lesions, a population‐based study was conducted in Linqu County, a high‐risk area of gastric cancer in China. Methylation status of p16 was evaluated by methylation‐specific polymerase chain reaction in 920 subjects with precancerous gastric lesions. H. pylori status was determined by 13C‐urea breath test and the density of H. pylori in biopsy specimens used for detecting methylation status was assessed by the modified Giemsa stain. The frequency of p16 methylation was significantly higher in subjects with H. pylori positive than those with H. pylori negative in each category of gastric lesion (p < 0.001, respectively). Compared with H. pylori negative, the odds ratios (ORs) of p16 methylation were markedly elevated in subjects with H. pylori positive for superficial gastritis (OR, 9.45; 95% confidence interval [CI]: 2.94–30.41), chronic atrophic gastritis (OR, 15.92; 95%CI: 7.60–33.36), intestinal metaplasia (OR, 4.46; 95%CI: 2.44–8.13), indefinite dysplasia (OR, 3.67; 95%CI: 1.90–7.10), and dysplasia (OR, 2.48; 95%CI: 1.02–5.99). Moreover, the frequencies of p16 methylation increased steadily with the severity of H. pylori density in gastric mucosa. Compared with H. pylori negative, the OR of p16 methylation was 1.02–16.13 times higher in subjects with mild H. pylori infection, and 2.69–38.73 times higher in those with moderate/severe infection, respectively. Our findings indicate that p16 methylation was significantly associated with H. pylori infection in precancerous gastric lesions, suggesting that H. pylori infection could potently induce methylation of p16 CpG island.

A large randomised controlled intervention trial to prevent gastric cancer by eradication of Helicobacter pylori in Linqu County, China: baseline results and factors affecting the eradication

Objective To clarify the full range of benefits and adverse consequences of Helicobacter pylori eradication as a strategy for gastric cancer prevention, the community-based intervention trial was launched in Linqu County, China. Design A total of 184 786 residents aged 25–54 years were enrolled in this trial and received 13C-urea breath test. H. pylori positive participants were assigned into two groups, either receiving a 10-day quadruple anti-H. pylori treatment or lookalike placebos together with a single dosage of omeprazole and bismuth. Results The prevalence of H. pylori in trial participants was 57.6%. A total of 94 101 subjects completed the treatment. The overall H. pylori eradication rate was 72.9% in the active group. Gender, body mass index, history of stomach disease, baseline delta over baseline-value of 13C-urea breath test, missed medication doses, smoking and drinking were independent predictors of eradication failure. The missed doses and high baseline delta over baseline-value were important contributors in men and women (all Ptrend<0.001). However, a dose-response relationship between failure rate and smoking or drinking index was found in men (all Ptrend<0.001), while high body mass index (Ptrend<0.001) and history of stomach disease were significant predictors in women. The treatment failure rate increased up to 48.8% (OR 2.87, 95% CI 2.24 to 3.68) in men and 39.4% (OR 2.67, 95% CI 1.61 to 4.42) in women with multiple factors combined. Conclusions This large community-based intervention trial to eradicate H. pylori is feasible and acceptable. The findings of this trial lead to a distinct evaluation of factors influencing eradication that should be generally considered for future eradication therapies. Trial registration number ChiCTR-TRC-10000979 in accordance with WHO ICTRP requirements.

Association between genetic polymorphisms of DNA base excision repair genes and evolution of precancerous gastric lesions in a Chinese population.

Base excision repair pathway may play an important role in repairing DNA damage related to Helicobacter pylori-induced inflammatory process. To evaluate the association between genetic polymorphisms of X-ray repair cross-complementing group 1 (XRCC1, Arg194Trp and Arg399Gln), adenosine diphosphate ribosyl transferase (ADPRT, Val762Ala), 8-oxoguanine DNA glycosylase (OGG1, Ser326Cys) and apurinic/apyrimidinic endonuclease 1 (APE1, Asp148Glu) and evolution of H.pylori-associated precancerous gastric lesions, a population-based cohort study was conducted in Linqu County, a high-risk area of gastric cancer in China. Genotypes were determined by polymerase chain reaction (PCR)-based denaturing high-performance liquid chromatography and PCR-restriction fragment length polymorphism analysis in 1281 H.pylori-infected subjects. We found that subjects carrying the combined XRCC1-194Arg/Trp+Trp/Trp genotype had an elevated chance of regression of gastric lesions [adjusted odds ratio (OR) = 1.44; 95% confidence interval (CI) = 1.06-1.96], whereas subjects carrying the XRCC1-399Arg/Gln+Gln/Gln genotype had a decreased chance of regression (OR = 0.68; 95% CI = 0.49-0.92). Stratified analysis indicated that an increased risk of progression was observed in subjects carrying the XRCC1-399Arg/Gln+Gln/Gln genotype (OR = 1.60; 95% CI = 1.09-2.36) or OGG1-326Ser/Cys+Cys/Cys genotype (OR = 1.95; 95% CI = 1.03-3.71) with intestinal metaplasia or dysplasia at baseline or carrying the XRCC1-399Arg/Gln+Gln/Gln genotype and smoking (OR = 1.58; 95% CI = 1.02-2.45). Furthermore, a significantly increased risk of progression was observed in subjects carrying one or two hazard genotypes of XRCC1-399 or OGG1-326, the OR was 2.83 (95% CI = 1.32-6.08), 2.22 (95% CI = 1.24-3.98) or 2.27 (95% CI = 1.26-4.10), respectively. These findings suggest that genetic polymorphisms in XRCC1-Arg194Trp, XRCC1-Arg399Gln and OGG1-Ser326Cys may play important roles in the evolution of H.pylori-associated gastric lesions in this high-risk population.

Detection of gastric carcinoma-associated MG7-Ag by serum immuno-PCR assay in a high-risk Chinese population, with implication for screening.

To evaluate gastric carcinoma‐associated antigen, MG7‐Ag, for detection of gastric cancer in a high‐risk population, a population‐based screening of gastric cancer was conducted in Linqu County, Shandong Province, China. In 2002 and 2003, a total of 2,710 participants aged 35–65 years received an endoscopic examination with 5 biopsies taken from standard sites with pathological diagnosis, and serum samples were collected to detect MG7‐Ag by serum‐based Immunopolymerase chain reaction (PCR) assay. The sensitivity and specificity of MG7‐Ag Immuno‐PCR assay in detecting of gastric cancer were assessed. Of 2,710 participants, 148 (5.46%) were determined to be MG7‐Ag positive. The sensitivity of MG7‐Ag Immuno‐PCR assay for the detection of gastric cancer was 77.5% (31 of 40 gastric cancer cases), the specificity was 95.62% (2,553 of 2,670 nongastric cancer subjects) and the accuracy was 73.12%. A total of 24 gastric cancer cases were in Stage I or II, of which 17 (70.8%) were MG7‐Ag positive. However, the proportion of MG7‐Ag positivity in subjects with superficial gastritis, chronic atrophic gastritis, intestinal metaplasia, indefinite dysplasia or dysplasia was ranged from 3.00% to 5.61% in comparison with 77.5% in those with gastric cancer. Our findings suggest that MG7‐Ag was a sensitive and specific serum biomarker and may have a potential for gastric cancer screening in the high‐risk population.

Genetic Polymorphisms of CYP2E1, GSTT1, GSTP1, GSTM1, ALDH2, and ODC and the Risk of Advanced Precancerous Gastric Lesions in a Chinese Population

There have been few studies of the associations of genetic polymorphisms with precancerous gastric lesions. We conducted a cross-sectional study to compare the prevalences of several genetic polymorphisms in 302 subjects with mild chronic atrophic gastritis with prevalences in 606 subjects with deep intestinal metaplasia or dysplasia. This stratified random sample of 908 subjects was selected and analyzed for genetic polymorphisms from 2,628 individuals who had gastric biopsies with histopathology in 1989 in Linqu County, Shandong Province, China. In subjects with mild chronic atrophic gastritis, the frequencies of the variant (less common) alleles of CYP2E1 RsaI, CYP2E1 DraI, GSTP1, ALDH2, and ODC were, respectively, 0.156, 0.201, 0.189, 0.190, and 0.428. The frequencies of the null genotypes of GSTM1 and GSTT1 in the mild chronic atrophic gastritis group were 0.509 and 0.565, respectively. Comparing mild chronic atrophic gastritis with deep intestinal metaplasia or any degree of dysplasia, we found no statistically significant associations with any genotype from these loci for dominant, additive, or recessive inheritance models. There was no statistically significant evidence of multiplicative interactions between any pair of genotypes based on CYP2E1 RsaI, CYP2E1 DraI, GSTP1, GSTM1, or GSTT1; nor between Helicobacter pylori status and any of these five loci; nor between smoking status and GSTP1, GSTM1, or GSTT1; nor between alcohol consumption and ALDH2. Statistically significant interactions were noted between salt consumption and GSTP1 and between sour pancake consumption and CYP2E1 RsaI. There was, moreover, a statistically significant interaction (odds ratio, 1.78; 95% confidence interval, 1.03-3.08) between CYP2E1 DraI and smoking at least one cigarette per day. A positive but not statistically significant interaction was also seen between CYP2E1 RsaI and smoking status. These polymorphisms do not seem to govern progression from mild chronic atrophic gastritis to advanced precancerous gastric lesions, but the effects of smoking may be accentuated in individuals carrying variants of CYP2E1.