Screening of 214 single nucleotide polymorphisms in 44 candidate cancer susceptibility genes: a case-control study on gastric and colorectal cancers in the Japanese population

MTRR rs1532268 polymorphism and gastric cancer risk: evidence from a meta-analysis

OBJECTIVE

The methionine synthase reductase (MTRR) gene encodes the MTRR enzyme involved in the metabolic pathway of homocysteine. Several studies investigated the effect of the MTRR rs1532268 gene polymorphism on the risk of gastric cancer (GC), but the results have been inconsistent.

METHODS

We performed a comprehensive and systematic search of PubMed, Google Scholar, MEDLINE, Science Direct, Scopus, CNKI, and Web of Science. Five studies were included in this meta-analysis to determine whether MTRR rs1532268 polymorphism contributes to the risk of GC.

RESULTS

Pooled data indicated that the MTRR rs1532268 polymorphism significantly increased GC risk under the allele comparison model (odds ratio [OR] = 1.14, 95% confidence interval [CI] = 1.01-1.29) and dominant model (OR = 1.14, 95% CI = 1.00-1.30). In the analysis stratified by ethnicity, no relationship was found in Whites or Asians.

CONCLUSION

Our meta-analysis suggests a positive correlation between MTRR rs1532268 polymorphism and GC development.

SNP Variation of RELN Gene and Schizophrenia in a Chinese Population: A Hospital-Based Case-Control Study

Aims: We aimed to explore whether RELN contributes to the vulnerability and severity of clinical symptoms of schizophrenia (SZ) in a Chinese population. Methods: The following were conducted in an adult Han Chinese population from southern China: case-control association analyses of 30 representative single nucleotide polymorphisms (SNPs) that were screened according to specific programs based on bioinformatics tools and former research and quantitative trait locus analyses with SNPs and psychiatric symptoms evaluated with the positive and negative symptoms scale. Results: A 4-SNP haplotype consisting of rs362814, rs39339, rs540058, and rs661575 was found to be significantly associated with SZ even after Bonferroni correction (χ² = 29.024, p = 6.42E-04, p _Bonf = 0.017), and the T-C-T-C haplotype was a protective factor for SZ (OR = 0.050, 95% CI = 0.004-0.705). Moreover, the 4-SNP haplotype showed a significant association with G16 (active social avoidance) after false discovery rate correction (χ² = 28.620, p = 1.697E-04, p _FDR = 0.025). In addition, P7 (hostility) was related to the haplotype comprising rs2229864, rs2535764, and rs262355 (χ² = 31.424, p = 2.103E-05, p _adjustment = 0.019) in quantitative trait loci analyses. Conclusion: Overall, this study showed several positive associations between RELN and SZ, as well as psychiatric symptoms, which not only supports the proposition that RELN is a susceptibility gene for SZ but also provides information on a genotype-phenotype correlation for SZ in a Chinese population.

Two-Sample Tests for High-Dimensional Linear Regression with an Application to Detecting Interactions

Motivated by applications in genomics, we consider in this paper global and multiple testing for the comparisons of two high-dimensional linear regression models. A procedure for testing the equality of the two regression vectors globally is proposed and shown to be particularly powerful against sparse alternatives. We then introduce a multiple testing procedure for identifying unequal coordinates while controlling the false discovery rate and false discovery proportion. Theoretical justifications are provided to guarantee the validity of the proposed tests and optimality results are established under sparsity assumptions on the regression coefficients. The proposed testing procedures are easy to implement. Numerical properties of the procedures are investigated through simulation and data analysis. The results show that the proposed tests maintain the desired error rates under the null and have good power under the alternative at moderate sample sizes. The procedures are applied to the Framingham Offspring study to investigate the interactions between smoking and cardiovascular related genetic mutations important for an inflammation marker.

Data Mining for Identification of Molecular Targets in Ovarian Cancer

Ovarian cancer is possibly the sixth most common malignancy worldwide, in Mexico representing the fourth leading cause of gynecological cancer death more than 70% being diagnosed at an advanced stage and the survival being very poor. Ovarian tumors are classified according to histological characteristics, epithelial ovarian cancer as the most common (~80%). We here used high-density microarrays and a systems biology approach to identify tissue-associated deregulated genes. Non-malignant ovarian tumors showed a gene expression profile associated with immune mediated inflammatory responses (28 genes), whereas malignant tumors had a gene expression profile related to cell cycle regulation (1,329 genes) and ovarian cell lines to cell cycling and metabolism (1,664 genes).

Association of MTRR A66G polymorphism with cancer susceptibility: Evidence from 85 studies

Methionine synthase reductase (MTRR) is a key regulatory enzyme involved in the folate metabolic pathway. Previous studies investigating the association of MTRR A66G polymorphism with cancer susceptibility reported inconclusive results. We performed the current meta-analysis to obtain a more precise estimation of the possible association. Published literatures were identified from PubMed, Embase and CBM databases up to October 2016. The strength of the association between the MTRR A66G polymorphism and cancer susceptibility was assessed using odds ratios (ORs) and the corresponding 95% confidence intervals (CIs). Eighty five published studies with 32,272 cases and 37,427 controls were included in this meta-analysis. Pooled results indicated that the MTRR A66G polymorphism was associated with an increased overall cancer risk (homozygous model: OR = 1.08, 95% CI = 1.02-1.15, P = 0.009; recessive model: OR = 1.06, 95% CI = 1.00-1.12, P < 0.001 and allele comparison: OR = 1.03, 95% CI = 1.00-1.06, P < 0.001). Stratification analysis further indicated significant associations in head and neck cancer, Caucasians, Africans, and high quality studies. However, to avoid the "false-positive report", the significant findings were assessed by the false-positive report probability (FPRP) test. Interestingly, the results of FPRP test revealed that the increased risk for MTRR A66G polymorphism among Africans need further validation due to the high probabilities of false-positive results. This meta-analysis suggests that the MTRR A66G polymorphism is associated with significantly increased cancer risk, a finding that needs to be confirmed in single large studies.

Gene polymorphisms in the ornithine decarboxylase-polyamine pathway modify gastric cancer risk by interaction with isoflavone concentrations

BACKGROUND

The study aimed to examine the association between genes encoding molecules in the ornithine decarboxylase (ODC)-polyamine pathway (ODC1, AMD1, NQO1, NOS2A, and OAZ2) and gastric cancer risk and whether the gene-phytoestrogen interaction modifies gastric cancer risk.

METHODS

Among 76 gastric cancer cases and their 1:4 matched controls within the Korean Multi-center Cancer Cohort, a total of 30 SNPs in five genes involved in the ODC pathway were primarily analyzed. The second-stage genotyping in 388 matched case-control sets was conducted to reevaluate the significant SNPs interacting with phytoestrogens during the primary analysis. The summary odds ratios (ORs) [95 % confidence intervals (CIs)] for gastric cancer were estimated. Interaction effects between the SNPs and plasma concentrations of phytoestrogens (genistein, daidzein, equol, and enterolactone) were evaluated.

RESULTS

In the pooled analysis, NQO1 rs1800566 showed significant genetic effects on gastric cancer without heterogeneity [OR 0.83 (95 % CI 0.70-0.995)] and a greater decreased risk at high genistein/daidzein levels [OR 0.36 (95 % CI 0.15-0.90) and OR 0.26 (95 % CI 0.10-0.64), respectively; p interaction < 0.05]. Risk alleles of AMD1 rs1279599, AMD1 rs7768897, and OAZ2 rs7403751 had a significant gene-phytoestrogen (genistein and daidzein) interaction effect to modify the development of gastric cancer. They had an increased gastric cancer risk at low isoflavone levels, but a decreased risk at high isoflavone levels (p interaction < 0.01).

CONCLUSIONS

Our findings suggest that common variants in the genes involved in the ODC pathway may contribute to the risk of gastric cancer possibly by modulating ODC polyamine biosynthesis or by interaction between isoflavones and NQO1, OAZ2, and AMD1.

Association between TLR2, MTR, MTRR, XPC, TP73, TP53 genetic polymorphisms and gastric cancer: a meta-analysis

OBJECTIVE

The aim of our meta-analyses is to test the association between six genetic polymorphisms and gastric cancer.

METHODS

A systematic search was performed for all the available candidate genes and gastric cancer among several online databases including PubMed, Embase, Web of Science, the Cochrane Library, CNKI and Wanfang online libraries. After a comprehensive screening, a total of six genes were harvested for the current meta-analyses. These genes include TLR2 (-196 to -174 ins>del), MTR (rs1805087), MTRR (rs1801394), XPC (rs2228001), TP73 (G4C14-A4T14), and TP53 (rs1042522).

RESULTS

Altogether 49 comparative studies among 11 776 cases and 18 633 controls were involved in our meta-analyses. TP53 rs1042522 polymorphism was shown to be associated with gastric cancer risk under the dominant model (P=0.02, OR=1.03, 95% CI=1.00-1.05). A subgroup meta-analysis indicated a significant association under dominant model between TP53 rs1042522 and gastric cancer in the Eastern Asians (P=0.03, OR=1.17, 95%=1.02-1.34).

CONCLUSIONS

These results suggest that TP53 rs1042522 polymorphism might contribute to the susceptibility of gastric cancer under the dominant model, especially in Eastern Asians.

Helicobacter pylori and gastric cancer

Infection with Helicobacter pylori is established as the major risk factor for gastric cancer development. Damage of the mucosal barrier due to H. pylori-induced inflammation enhances the carcinogenic effect of other risk factors such as salt intake or tobacco smoking. The genetic disposition of both the bacterial strain and the host can increase the potential towards gastric cancer formation. Genetic variance of the bacterial proteins CagA and VacA is associated with a higher gastric cancer risk, as are polymorphisms and epigenetic changes in host gene coding for interleukins (IL1β, IL8), transcription factors (CDX2, RUNX3) and DNA repair enzymes. Application of high-throughput assays for genome-wide assessment of either genetic structural variance or gene expression patterns may lead to a better understanding of the pathobiological background of these processes, including the underlying signaling pathways. Understanding of the stepwise alterations that take place in the transition from chronic atrophic gastritis, via metaplastic changes, to invasive neoplasia is vital to define the 'point of no return' before which eradication of H. pylori has the potential to prevent gastric cancer. Currently, eradication as preventive strategy is only recommended for high-incidence regions in Asia; large population studies with an adequate follow-up are required to demonstrate the effectiveness of such an approach in Western populations.

Dietary aflatoxin B1 intake, genetic polymorphisms of CYP1A2, CYP2E1, EPHX1, GSTM1, and GSTT1, and gastric cancer risk in Korean

PURPOSE

We investigated the effects of aflatoxin B1 (AFB1) intake, genetic polymorphisms of AFB1 metabolic enzymes, and interactions between the polymorphisms and intake of AFB1 with regard to the risk of gastric cancer in Korean.

METHODS

The participants in the study included 477 gastric cancer patients and 477 age- and sex-matched control subjects. Direct interviews and a structured questionnaire were used to determine the level of exposure to AFB1, and the GoldenGate assay and multiplex polymerase chain reaction were used for genotypic analyses of the cytochrome P450 1A2 (CYP1A2), cytochrome P450 1E1, epoxide hydrolase 1, and glutathione S-transferase genes.

RESULTS

The probable daily intake of AFB1 was significantly higher among gastric cancer patients than among control subjects (cases vs. controls: 1.91 ± 0.87 vs. 1.65 ± 0.72 ng/kg bw/day, p < 0.0001), and increased AFB1 intake was significantly associated with an elevated risk of gastric cancer (odds ratio 1.94; 95 % confidence interval 1.43-2.63). However, genetic polymorphisms of AFB1 metabolic enzymes were not associated with gastric cancer, with the exception of CYP1A2. Moreover, there was no interaction between AFB1 intake and the genotypes of metabolic enzymes that affect gastric cancer risk.

CONCLUSIONS

Our results suggest that dietary AFB1 exposure might be associated with a risk of gastric cancer. However, the effect of AFB1 on gastric carcinogenesis may not be modulated by genetic polymorphisms of AFB1 metabolic enzymes.

Gene polymorphisms of NOD1 and interleukin-8 influence the susceptibility to erosive esophagitis in Helicobacter pylori infected Japanese population

Helicobacter pylori (H. pylori) infection generally protects patients from erosive esophagitis through reduction of acid production due to gastric mucosal atrophy. However, there are H. pylori infected patients who still have erosive esophagitis. The reason for this discrepancy remains unclear. We have previously reported that polymorphisms in IL-8 promoter region influence the susceptibility of H. pylori related diseases. On the other hand, nucleotide-binding oligomerization domain 1 (NOD1) is known to play an important role in H. pylori infection. Hence, we hypothesized polymorphisms of these two molecules in H. pylori infected patients may influence the susceptibility to erosive esophagitis. Genomic DNA was extracted from 312 H. pylori infected Japanese, consisting of 110 patients with erosive esophagitis and 202 healthy controls. ND1+32656 T/GG and IL-8-251 A/T polymorphisms were genotyped by direct sequencing. ND1+32656 GG allele and IL-8-251 T/T allele increased the risk of erosive esophagitis with odds ratio (OR) of 1.9 (95% confidence interval (CI) 1.1-3.0, p=0.013) and 1.7 (95% CI 1.1-2.8, p=0.036), respectively. Combination of these two alleles increased the risk with OR of 3.2(95% CI 1.6-6.5, p=0.001). In conclusion, ND1+32656 GG and IL-8-251 T/T allele may be associated with less reactivity to H. pylori infection, and may increase the risk of erosive esophagitis even in H. pylori infected Japanese population.

Genetic susceptibility factors on genes involved in the steroid hormone biosynthesis pathway and progesterone receptor for gastric cancer risk

Background

The objective of the study was to investigate the role of genes (HSD3B1, CYP17A1, CYP19A1, HSD17B2, HSD17B1) involved in the steroid hormone biosynthesis pathway and progesterone receptor (PGR) in the etiology of gastric cancer in a population-based two-phase genetic association study.

Methods

In the discovery phase, 108 candidate SNPs in the steroid hormone biosynthesis pathway related genes and PGR were analyzed in 76 gastric cancer cases and 322 controls in the Korean Multi-Center Cancer Cohort. Statistically significant SNPs identified in the discovery phase were re-evaluated in an extended set of 386 cases and 348 controls. Pooled- and meta-analyses were conducted to summarize the results.

Results

Of the 108 SNPs in steroid hormone biosynthesis pathway related genes and PGR analyzed in the discovery phase, 23 SNPs in PGR in the recessive model and 10 SNPs in CYP19A1 in the recessive or additive models were significantly associated with increased gastric cancer risk (p<0.05). The minor allele frequencies of the SNPs in both the discovery and extension phases were not statistically different. Pooled- and meta-analyses showed CYP19A1 rs1004982, rs16964228, and rs1902580 had an increased risk for gastric cancer (pooled OR [95% CI] = 1.22 [1.01–1.48], 1.31 [1.03–1.66], 3.03 [1.12–8.18], respectively). In contrast, all PGR SNPs were not statistically significantly associated with gastric cancer risk.

Conclusions

Our findings suggest CYP19A1 that codes aromatase may play an important role in the association of gastric cancer risk and be a genetic marker for gastric cancer susceptibility.

An integrated approach to identify causal network modules of complex diseases with application to colorectal cancer

BACKGROUND

Many methods have been developed to identify disease genes and further module biomarkers of complex diseases based on gene expression data. It is generally difficult to distinguish whether the variations in gene expression are causative or merely the effect of a disease. The limitation of relying on gene expression data alone highlights the need to develop new approaches that can explore various data to reflect the casual relationship between network modules and disease traits.

METHODS

In this work, we developed a novel network-based approach to identify putative causal module biomarkers of complex diseases by integrating heterogeneous information, for example, epigenomic data, gene expression data, and protein-protein interaction network. We first formulated the identification of modules as a mathematical programming problem, which can be solved efficiently and effectively in an accurate manner. Then, we applied our approach to colorectal cancer (CRC) and identified several network modules that can serve as potential module biomarkers for characterizing CRC. Further validations using three additional gene expression datasets verified their candidate biomarker properties and the effectiveness of the method. Functional enrichment analysis also revealed that the identified modules are strongly related to hallmarks of cancer, and the enriched functions, such as inflammatory response, receptor and signaling pathways, are specific to CRC.

RESULTS

Through constructing a transcription factor (TF)-module network, we found that aberrant DNA methylation of genes encoding TF considerably contributes to the activity change of some genes, which may function as causal genes of CRC, and that can also be exploited to develop efficient therapies or effective drugs.

CONCLUSION

Our method can potentially be extended to the study of other complex diseases and the multiclassification problem.

Association of estrogen receptor beta variants and serum levels of estradiol with risk of colorectal cancer: a case control study

Background

Endogenous estrogens may play a vital role in colorectal tumorigenesis. Estrogen receptor beta is the predominant subtype which mediates the biological effect of estrogens, while loss of expression of estrogen receptor beta has been indicated as a common step in the development of colorectal cancer (CRC). Epidemiological studies have revealed several functional polymorphisms of estrogen receptor beta (ESR2) for cancer risk, but relevant study in CRC is limited, particularly in men. This study aimed to investigate the association of circulating estradiol and variations of ESR2 with CRC risk in men.

Methods

We initiated a case–control study consisting of 390 patients with CRC and 445 healthy controls in men only. We genotyped ESR2 single nucleotide polymorphisms (SNPs) rs1256049 and rs4986938 and measured serum estradiol concentration using chemilluminescence immunoassay. Multivariable logistic regression model was performed to evaluate the associations between these variables and CRC risk.

Results

ESR2 rs1256049 CT/TT genotypes were associated with reduced risk of CRC (odds ratio [OR], 0.7, 95% confidence interval [CI], 0.5–1.0), while rs4986938 CT/TT genotypes were associated with increased risk of CRC (OR, 1.5, 95% CI, 1.0–2.1). In addition, the CRC risk increased with the number of risk genotypes of these two SNPs in a dose–response manner (P_trend, 0.003). Specifically, subjects carrying risk genotypes of both SNPs had the highest risk of CRC (OR, 2.0, 95% CI, 1.3–3.3.). Moreover, serum estradiol concentration alone was associated with risk of CRC in men (OR, 1.2, 95% CI, 1.0–1.3). However, individuals presenting both rs4986938 CT/TT genotypes and high level of serum estradiol had a high risk of CRC (OR, 2.3, 95% CI, 1.4–3.9), compared with those presenting CC genotype and low level of serum estradiol. The similar joint results were not observed for SNP rs1256049.

Conclusions

These results suggest that endogenous estrogen and genetic variations in ESR2 may individually, or more likely jointly, affect CRC risk in male Han Chinese population, while larger studies are needed to validate our findings.

Association of variants in genes involved in environmental chemical metabolism and risk of cryptorchidism and hypospadias

We hypothesized that single-nucleotide polymorphisms (SNPs) of genes involved in environmental endocrine disruptors (EEDs) metabolism might influence the risk of male genital malformations. In this study, we explored for association between 384 SNPs in 15 genes (AHR, AHRR, ARNT, ARNT2, NR1I2, RXRA, RXRB, RXRG, CYP1A1, CYP1A2, CYP1B1, CYP2B6, CYP3A4, CYP17A1 and CYP19A1) and risk of cryptorchidism (CO) and hypospadias (HS) in 334 Japanese (JPN) males (141 controls, 95 CO and 98 HS) and 187 Italian (ITA) males (129 controls and 58 CO). In the JPN study group, five SNPs from ARNT2 (rs2278705 and rs5000770), CYP1A2 (rs2069521), CYP17A1 (rs4919686) and NR1I2 (rs2472680) were significantly associated at both allelic and genotypic levels with risk of at least one genital malformation phenotype. In the ITA study group, two SNPs in AHR (rs3757824) and ARNT2 (rs1020397) were significantly associated with risk of CO. Interaction analysis of the positive SNPs using multifactor dimensionality reduction demonstrated that synergistic interaction between rs2472680, rs4919686 and rs5000770 had 62.81% prediction accuracy for CO (P=0.011) and that between rs2069521 and rs2278705 had 69.98% prediction accuracy for HS (P=0.001) in JPN population. In a combined analysis of JPN and ITA population, the most significant multi-locus association was observed between rs5000770 and rs3757824, which had 65.70% prediction accuracy for CO (P=0.055). Our findings indicate that genetic polymorphisms in genes involved in EED metabolism are associated with risk of CO and HS.

Gastric carcinogenesis

INTRODUCTION

In most patients, gastric cancer is diagnosed in advanced stage. Curative treatment options are limited and the mortality is high. The process of gastric carcinogenesis is triggered by Helicobacter pylori-driven gastritis and is further characterized by its complexity of interaction with other risk factors. Health care systems are challenged for the improvement of prevention, early diagnosis, and effective treatments.

METHODS

An extensive literature research has been performed to elucidate the interplay between etiological factors involved in gastric carcinogenesis.

RESULTS

H. pylori is the most important carcinogen for gastric adenocarcinoma. Evidence is provided by experiments including animal studies as well as clinical observational and interventional studies in humans. Eradication has the potential to prevent gastric cancer and offers the greatest benefit if performed before premalignant changes of the gastric mucosa have occurred. Bacterial virulence factors are essential players in modulating the immune response involved in the initiation of the carcinogenesis in the stomach. Host genetic factors contribute to the regulation of the inflammatory response and in the aggravation of mucosal damage. The harmful role of environmental factors is restricted to salt intake and smoking of tobacco. The ingestion of fruit and vegetables has some protective effect.

CONCLUSION

Infection with H. pylori is the major risk factor for gastric cancer development, and thus, eradication of the Helicobacter offers a promising best option for prevention of the disease. Bacterial virulence, host genetic factors, and environmental influences are interacting in the multifactorial process of gastric carcinogenesis.

Association between polymorphism of the tumor necrosis factor alpha-308 gene promoter and colon cancer in the Chinese population

Tumor necrosis factor (TNF) is a type of cytokine that inhibits tumorigenesis. Several studies have assessed the relationship between the polymorphism of TNF-alpha 308G/A and the susceptibility to colon cancer; however, the results have been controversial. A case-control study was carried out to investigate whether TNF-alpha 308G/A gene polymorphism was associated with the risk of colon cancer in a group of 180 cases and 180 controls from Heilongjiang, China. DNA was isolated from peripheral blood, and gene polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism. Results of our study showed that colon cancer cases had a significantly higher frequency of TNF-alpha 308AA genotype (odds ratio=9.42, 95% confidence interval=1.18, 75.15; p=0.03) than controls. When stratified by the tumor location, tumor size, growth pattern, differentiation, and stage of colon cancer, no statistically significant results was observed. The present study demonstrated that TNF-alpha 308AA genotype was associated with a higher risk of colon cancer in the Chinese population. Confirmation of these findings in other populations is required.

A population-based study of IGF axis polymorphisms and the esophageal inflammation, metaplasia, adenocarcinoma sequence

BACKGROUND & AIMS

Insulin-like growth factor (IGF) axis plays a key role in cell development, proliferation, and survival and is implicated in the etiology of several cancers. Few studies have examined the relationship between genetic variation of this axis and esophageal adenocarcinoma (EAC) or its precursors.

METHODS

In a population-based case-control study, we investigated the association of common polymorphisms of IGF-1, IGF-2, IGF-1 receptor, IGF binding protein-3, growth hormones (GH) 1 and GH2, and GH receptor with reflux esophagitis (RE), Barrett esophagus (BE), and EAC. Two hundred and thirty RE, 224 BE, 227 EAC cases, and 260 controls were studied. Gene polymorphisms were identified using publicly available online resources; 102 IGF axis tag and putatively functional single-nucleotide polymorphisms (SNPs) were analyzed using MassARRAY iPLEX and Taqman assays. Results were analyzed using Haploview.

RESULTS

Three polymorphisms were disease-associated. IGF1 SNP rs6214 was associated with BE (adjusted P = .039). Using GG genotype as reference, odds ratio for BE in AA (wild-type) was 0.43 (95% confidence interval [CI], 0.24-0.75). GH receptor SNP rs6898743 was associated with EAC (adjusted P = .0112). With GG as reference, odds ratio for EAC in CC (wild-type) genotype was 0.42 (95% CI, 0.23-0.76). IGF1 (CA)(17) 185-bp allele was associated with RE (adjusted P = .0116). Using IGF1(non17) as reference, odds ratio for RE in IGF1(17) carriers was 7.29 (95% CI, 1.57-46.7).

CONCLUSIONS

In this study, 3 polymorphisms of IGF genes were associated with EAC or its precursors. These polymorphisms may be markers of disease risk; independent validation of our findings is required. These results suggest the IGF pathway is involved in EAC development.

Negative lymph node count is associated with survival of colorectal cancer patients, independent of tumoral molecular alterations and lymphocytic reaction

OBJECTIVES

The number of recovered lymph nodes is associated with good prognosis among colon cancer patients undergoing surgical resection. However, little has been known on prognostic significance of lymph node count after adjusting for host immune response to tumor and tumoral molecular alterations, both of which are associated with the lymph node count and patient survival.

METHODS

Among 716 colorectal cancers (stages 1-4) in two independent prospective cohorts, we examined patient survival in relation to the negative lymph node count and lymph node ratio (LNR; positive to total lymph node counts). Cox proportional hazard models were used to compute hazard ratio of deaths, adjusted for patient, specimen, and tumoral characteristics, including lymphocytic reactions, KRAS and BRAF mutations, p53 expression, microsatellite instability (MSI), the CpG island methylator phenotype (CIMP), and LINE-1 methylation.

RESULTS

Compared with patients with 0-3 negative lymph nodes, patients with 7-12 and > or =13 negative nodes experienced a significant reduction in cancer-specific and overall mortality in Kaplan-Meier analysis (log-rank P<0.0001), univariate Cox regression (P(trend)<0.0001), and multivariate analysis (P(trend)<0.0003), independent of potential confounders examined. The benefit associated with the negative node count was apparent across all stages, although the effect was significantly greater in stages 1-2 than stages 3-4 (P(interaction)=0.002). In both stage 3 and stage 4, smaller LNR was associated with improved survival (log-rank P<0.0001).

CONCLUSIONS

The negative lymph node count is associated with improved survival of colorectal cancer patients, independent of lymphocytic reactions to tumor and tumoral molecular features including MSI, CIMP, LINE-1 hypomethylation and BRAF mutation.

A cohort study of STMN1 expression in colorectal cancer: body mass index and prognosis

OBJECTIVES

STMN1 (stathmin or oncoprotein-18) destabilizes microtubules and reorganizes cytoskeleton, and functions in cell cycle progression and cell migration. STMN1 activity is influenced by p53, p27, and the PI3K/AKT pathway. However, its prognostic significance in colon cancer is uncertain.

METHODS

Utilizing 546 colorectal cancers (stage I-IV) from two independent prospective cohort studies (the Nurses' Health Study and Health Professionals Follow-up Study), STMN1 expression was detected in 297 (54%) tumors by immunohistochemistry. Cox proportional hazard models computed hazard ratios (HRs) of mortality, adjusted for clinical and tumoral features, including microsatellite instability (MSI), CpG island methylation phenotype (CIMP), LINE-1 hypomethylation, KRAS, BRAF, PIK3CA, p53, p21, p27, cyclin D1, beta-catenin, fatty acid synthase, FASN, and COX-2.

RESULTS

Five-year colorectal cancer-specific survival was 78% in STMN1-positive patients and 76% in STMN1-negative patients (log-rank P=0.30). STMN1-positivity was not significantly associated with cancer-specific survival in univariate analysis with HR of 0.82 (95% confidence interval (CI), 0.59-1.14), which became significant in multivariate analysis (adjusted HR=0.60; 95% CI, 0.41-0.87; P=0.0078). Notably, the prognostic effect of obesity (body mass index, BMI> or =30 kg/m2) significantly differed by STMN1 (P(interaction)=0.005). Obesity was associated with high cancer-specific mortality among STMN1-positive patients (adjusted HR=2.36; 95% CI, 1.18-4.69), whereas obesity was not associated with high mortality among STMN1-negative patients (adjusted HR=0.51; 95% CI, 0.24-1.07).

CONCLUSIONS

STMN1 overexpression in colorectal cancer is independently associated with improved survival. The adverse prognostic effect of obesity was limited to patients with STMN1-positive tumors. Our findings suggest the presence of a tumor (STMN1)-host (BMI) interaction that potentially determines clinical outcome.

Glutathione S-transferase P1 Ile105Val polymorphism and colorectal cancer risk: a meta-analysis and HuGE review

Colorectal cancer is the third most common form of cancer and the fourth most frequent cause of cancer deaths worldwide. Its development is influenced by both environmental and genetic factors. The glutathione S-transferase P1 gene (GSTP1) is a particularly attractive candidate for colorectal cancer susceptibility because it codes the enzyme involved in the metabolism of environmental carcinogens such as polycyclic aromatic hydrocarbons (PAHs). However, epidemiologic findings have been inconsistent. To investigate a putative association of GSTP1 Ile105Val polymorphism with the risk of colorectal cancer, we performed a meta-analysis and HuGE review of 16 published case-control studies (involving a total of 4386 colorectal cancer patients and 7127 controls). We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. Overall, the comparison of Val versus Ile allele showed no differential susceptibility to colorectal cancer (OR=0.98, 95% CI: 0.92-1.04). A protective effect was found in recessive, with an OR of 0.86 (95% CI: 0.76-0.98). Whereas no significant association was observed in either dominant or codominant model. In stratified subgroup analysis, no effect of Val allele was seen in subjects of Caucasian and Asian descent, and in healthy and hospital controls. In conclusion, the meta-analysis suggests that the GSTP1 Ile105Val polymorphism is unlikely to increase considerably the risk of sporadic colorectal cancer, and it should be confirmed in further studies.

Zebrafish 17beta-hydroxysteroid dehydrogenases: an evolutionary perspective

The term 17beta-hydroxysteroid dehydrogenase (17beta-HSD) describes an enzyme that stereospecifically reduces or oxidizes a keto- or hydroxy group at C17 of the steroid scaffold, respectively. Fourteen mammalian 17beta-HSDs have been identified so far and nine sequence homologs are found in zebrafish. 17beta-HSDs additionally active in fatty acid metabolism display high sequence conservation and widespread tissue expression. Homologs of these multifunctional 17beta-HSDs have been identified in flies, worms and yeast, and steroid-converting activity was demonstrated in some cases. The "classical" 17beta-HSDs, types 1, 2 and 3, are steroid-specific enzymes expressed in few tissues. They may have arisen at the beginning of vertebrate evolution allowing new, differently controlled modes of steroid hormone action. These findings reflect on two aspects: (1) the evolutionary origin of steroid-specific enzymes and (2) a possible conservation of steroid hormone function in invertebrates through currently unknown mechanisms.

Polymorphisms in estrogen- and androgen-metabolizing genes and the risk of gastric cancer

Androgens and estrogens may play a role in gastric cancer etiology. To investigate the association of gastric cancer with single-nucleotide polymorphisms (SNPs) in six genes (COMT, CYP1B1, CYP17A1, CYP19A1, HSD17B1 and SHBG) involved in estrogen and androgen synthesis and metabolism, 58 haplotype-tagging SNPs were genotyped in 295 gastric cancer cases and 415 controls from a population-based study in Poland. We assessed differences in haplotype frequency between cases and controls using a global score test and calculated multivariate odds ratios (ORs) and 95% confidence intervals (CIs) for individual haplotypes using logistic regression. We found associations in one linkage disequilibrium (LD) block containing the 3' untranslated region of COMT (rs9332377, rs165728, rs165849 and rs1110478), global score test (df = 4, P = 0.033). Relative to the most frequent GATA haplotype, the GATG haplotype was associated with statistically significant increased gastric cancer risk (OR = 1.50, 95% CI: 1.06-2.12; false discovery rate (FDR) value = 0.459) and the AACA haplotype with borderline increased risk (OR = 1.36, 95% CI = 1.00-1.85; FDR = 0.50). We also found associations for the LD block containing part of the SHBG coding region (rs6258, rs6259, rs2955617, rs1641544 and rs1641537). The CACCC haplotype was associated with statistically significant lower gastric cancer risk relative to the referent CGACC haplotype (OR = 0.55, 95% CI = 0.34-0.90; FDR = 0.459), but the overall score test was statistically non-significant. No other statistically significant associations were observed. In summary, we found possible associations between gastric cancer and polymorphisms in COMT, involved in estrogen inactivation, and SHBG, a modulator of hormone bioavailability. These findings should be interpreted cautiously until replicated in other studies.