Effect of COX2 -765G>C and c.3618A>G polymorphisms on the risk and survival of sporadic colorectal cancer

Examining SNP-SNP interactions and risk of clinical outcomes in colorectal cancer using multifactor dimensionality reduction based methods

Background: SNP interactions may explain the variable outcome risk among colorectal cancer patients. Examining SNP interactions is challenging, especially with large datasets. Multifactor Dimensionality Reduction (MDR)-based programs may address this problem.

Objectives: 1) To compare two MDR-based programs for their utility; and 2) to apply these programs to sets of MMP and VEGF-family gene SNPs in order to examine their interactions in relation to colorectal cancer survival outcomes.

Methods: This study applied two data reduction methods, Cox-MDR and GMDR 0.9, to study one to three way SNP interactions. Both programs were run using a 5-fold cross validation step and the top models were verified by permutation testing. Prognostic associations of the SNP interactions were verified using multivariable regression methods. Eight datasets, including SNPs from MMP family genes (n = 201) and seven sets of VEGF-family interaction networks (n = 1,517 SNPs) were examined.

Results: ∼90 million potential interactions were examined. Analyses in the MMP and VEGF gene family datasets found several novel 1- to 3-way SNP interactions. These interactions were able to distinguish between the patients with different outcome risks (regression p-values 0.03–2.2E-09). The strongest association was detected for a 3-way interaction including CHRM3.rs665159_EPN1.rs6509955_PTGER3.rs1327460 variants.

Conclusion: Our work demonstrates the utility of data reduction methods while identifying potential prognostic markers in colorectal cancer.

MicroRNA binding site polymorphism in inflammatory genes associated with colorectal cancer: literature review and bioinformatics analysis

Inflammation, among environmental risk factors, is one of the most important contributors to colorectal cancer (CRC) development. In this way, studies revealed that the incidence of CRC in inflammatory bowel disease patients is up to 60% higher than the general population. MicroRNAs (miRNAs), small noncoding RNA molecules, have attracted excessive attention due to their fundamental role in various aspects of cellular biology, such as inflammation by binding to the 3'-untranslated regions (3'-UTR) of pro and anti-inflammatory genes. Based on multiple previous studies, SNPs at 3'-UTR can affect miRNA recognition elements by changing the thermodynamic features and secondary structure. This effect can be categorized, based on the number of changes, into four groups, including break, decrease, create, and enhance. In this paper, we will focus on functional variants in miRNA binding sites in inflammatory genes, which can modulate the risk of CRC by both investigating previous studies, regarding miRSNPs in inflammatory genes associated with CRC and recruiting in silico prediction algorithms to report putative miRSNPs in 176 inflammatory genes. In our analysis, we achieved 110 miRSNPs in 3'-UTR of 67 genes that seem good targets for future researches.

MicroRNA-binding site polymorphisms and risk of colorectal cancer: A systematic review and meta-analysis

Genetic variations in miRNAs binding site might participate in cancer risk. This study aimed to systematically review the association between miRNA-binding site polymorphisms and colorectal cancer (CRC). Electronic literature search was carried out on PubMed, Web of Science (WOS), Scopus, and Embase. All types of observational studies till 30 November 2018 were included. Overall 85 studies (21 SNPs) from two systematic searches were included analysis. The results showed that in the Middle East population, the minor allele of rs731236 was associated with decreased risk of CRC (heterozygote model: 0.76 [0.61-0.95]). The minor allele of rs3025039 was related to increased risk of CRC in East Asian population (allelic model: 1.25 [1.01-1.54]). Results for rs3212986 were significant in overall and subgroup analysis (P < .05). For rs1801157 in subgroup analysis the association was significant in Asian populations (including allelic model: 2.28 [1.11-4.69]). For rs712, subgroup analysis revealed a significant (allelic model: 1.41 [1.23-1.61]) and borderline (allelic model: 0.92 [0.84-1.00]) association in Chinese and Czech populations, respectively. The minor allele of rs17281995 increased risk of CRC in different genetic models (P < .05). Finally, rs5275, rs4648298, and rs61764370 did not show significant associations. In conclusion, minor allele of rs3025039, rs3212986, and rs712 polymorphisms increases the risk of CRC in the East Asian population, and heterozygote model of rs731236 polymorphism shows protective effect in the Middle East population. In Europeans, the minor allele of rs17281995 may increase the risk of CRC, while rs712 may have a protective effect. Further analysis based on population stratifications should be considered in future studies.

Single nucleotide polymorphism rs4648298 in miRNAs hsa-miR21 and hsa-miR590 binding site of COX gene is a strong colorectal cancer determinant

Background

Genetic determinants are considered as driving forces in development colorectal cancer (CRC), a malignancy that ranks as the second cause of cancer death in the world. Single nucleotide polymorphisms (SNPs), are considered as the main genetic factor in cancers susceptibility. MicroRNAs are critical players in posttranslational gene regulation by binding to their specific recognition sequences located at 3' untranslated region (UTR) of mRNAs. In present study we have elucidated the role of 9,850 A > G (rs4648298), in development of sporadic CRC in Iranian population.

Methods

A case-control study using 88 CRC patients and 88 noncancerous counterparts was undertaken in order to determine rs4648298 genotypes using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Also, a meta-analysis was performed based on 9 articles accessed via the MEDLINE, Cochrane review, Google Scholar and Scopus databases.

Results

AA genotype was determined to be associated with significant decreased risk of CRC in our study population [odds ratio (OR) =0.14; 95% confidence interval (CI), 0.05-0.34; P<0.001]. In a meta-analysis on 6 risk estimates for the AG versus AA genotype, we found a significant inverse association between AG SNPs and risk of gastric adenocarcinoma, CRC, breast cancer and prostate cancer (OR =0.86; 95% CI, 0.76-0.98; P<0.02).

Conclusions

Our results suggest significant correlation between rs4648298 polymorphism and CRC risk in Iranian population.

The -765G>C polymorphism in the cyclooxygenase-2 gene and digestive system cancer: a meta-analysis

BACKGROUND

Published data regarding associations between the -765G>C polymorphism in cyclooxygenase-2 (COX-2) gene and digestive system cancer risk have been inconclusive. The aim of this study was to comprehensively evaluate the genetic risk of the -765G>C polymorphism in the COX-2 gene for digestive system cancer.

MATERIALS AND METHODS

A search was performed in Pubmed, Medline (Ovid), Embase, CNKI, Weipu, Wanfang and CBM databases, covering all studies until Feb 10, 2014. Statistical analysis was performed using Revman5.2.

RESULTS

A total of 10,814 cases and 16,174 controls in 38 case-control studies were included in this meta-analysis. The results indicated that C allele carriers (GC+CC) had a 20% increased risk of digestive system cancer when compared with the homozygote GG (odds ratio (OR)=1.20, 95% confidence interval (CI), 1.00-1.44 for GC+CC vs GG). In the subgroup analysis by ethnicity, significant elevated risks were associated with C allele carriers (GC+CC) in Asians (OR = 1.46, 95% CI=1.07-2.01, and p=0.02) and Africans (OR=2.12, 95% CI=1.57-2.87, and p< 0.00001), but not among Caucasians, Americans and mixed groups. For subgroup analysis by cancer type (GC+CC vs GG), significant associations were found between the -765G>C polymorphism and higher risk for gastric cancer (OR=1.64, 95% CI=1.03-2.61, and p=0.04), but not for colorectal cancer, oral cancer, esophageal cancer, and others. Regarding study design (GC+CC vs GG), no significant associations were found in then population-based case-control (PCC), hospital-based case-control (HCC) and family-based case-control (FCC) studies.

CONCLUSIONS

This meta-analysis suggested that the -765G>C polymorphism of the COX-2 gene is a potential risk factor for digestive system cancer in Asians and Africans and gastric cancer overall.

Pharmacogenomics of cyclooxygenases

Cyclooxygenases (COX-1 and COX-2) are key enzymes in several physiopathological processes. Many adverse drugs reactions to NSAIDs are attributable to COX-inhibition. The genes coding for these enzymes (PTGS1 and PTGS2) are highly variable, and variations in these genes may underlie the risk of developing, or the clinical evolution of, several diseases and adverse drug reactions. We analyze major variations in the PTGS1 and PTGS2 genes, allele frequencies, functional consequences and population genetics. The most salient clinical associations of PTGS gene variations are related to colorectal cancer and stroke. In many studies, the SNPs interact with NSAIDs use, dietary or environmental factors. We provide an up-to-date catalog of PTGS clinical associations based on case–control studies and genome-wide association studies, and future research suggestions.

Role of genetic polymorphisms in NFKB-mediated inflammatory pathways in response to primary chemoradiation therapy for rectal cancer

PURPOSE

To investigate whether polymorphisms of genes related to inflammation are associated with pathologic response (primary endpoint) in patients with rectal cancer treated with primary chemoradiation therapy (PCRT).

METHODS AND MATERIALS

Genomic DNA of 159 patients with locally advanced rectal cancer treated with PCRT was genotyped for polymorphisms rs28362491 (NFKB1), rs1213266/rs5789 (PTGS1), rs5275 (PTGS2), and rs16944/rs1143627 (IL1B) using TaqMan single nucleotide polymorphism genotyping assays. The association between each genotype and pathologic response (poor response vs complete or partial response) was analyzed using logistic regression models.

RESULTS

The NFKB1 DEL/DEL genotype was associated with pathologic response (odds ratio [OR], 6.39; 95% confidence interval [CI], 0.78-52.65; P=.03) after PCRT. No statistically significant associations between other polymorphisms and response to PCRT were observed. Patients with the NFKB1 DEL/DEL genotype showed a trend for longer disease-free survival (log-rank test, P=.096) and overall survival (P=.049), which was not significant in a multivariate analysis that included pathologic response. Analysis for 6 polymorphisms showed that patients carrying the haplotype rs28362491-DEL/rs1143627-A/rs1213266-G/rs5789-C/rs5275-A/rs16944-G (13.7% of cases) had a higher response rate to PCRT (OR, 8.86; 95% CI, 1.21-64.98; P=.034) than the reference group (rs28362491-INS/rs1143627-A/rs1213266-G/rs5789-C/rs5275-A/rs16944-G). Clinically significant (grade ≥2) acute organ toxicity was also more frequent in patients with that same haplotype (OR, 4.12; 95% CI, 1.11-15.36; P=.037).

CONCLUSIONS

Our results suggest that genetic variation in NFKB-related inflammatory pathways might influence sensitivity to primary chemoradiation for rectal cancer. If confirmed, an inflammation-related radiogenetic profile might be used to select patients with rectal cancer for preoperative combined-modality treatment.

Prognostic value of cyclooxygenase-2 gene polymorphisms in advanced non-small cell lung cancer patients treated with first-line platinum-based chemotherapy

AIM

Cyclooxygenase-2 (COX-2) plays an important role in cell apoptosis, angiogenesis and tumor invasion, and over-expression of COX-2 is associated with tumor development and occurrence. The aim of this study is to investigate the association between COX-2 polymorphisms and clinical outcomes in advanced non-small cell lung cancer (NSCLC) patients treated with first-line platinum-based chemotherapy.

METHODS

A total of 190 patients with IIIB or IV NSCLC who received platinum-based chemotherapy were recruited in this study. Four functional COX-2 polymorphisms, including rs689465, rs689466, rs3218625 and rs20417, were genotyped by PCR-based restriction fragment length polymorphism methods. Kaplan-Meier methods were used to compare survival by different genotypes. Cox proportional hazard models were used to identify independently significant variables.

RESULTS

The rs689465 AA genotype was significantly associated with longer overall survival (OS) (13.0 months vs 8.8 months, P = 0.019 for log-rank test; hazard ratio [HR] 0.624; 95% confidence internal [CI] 0.418-0.931) and progression-free survival (5.3 months vs 4.0 months, P = 0.018 for log-rank test; HR 0.627; 95% CI 0.421-0.934) compared with AG or GG genotype, especially in patients with adenocarcinoma (P = 0.002), performance status of 1 (P = 0.009) and stage IV disease (P = 0.012), and treated with gemcitabine-based chemotherapy (P = 0.012). Multivariate regression analysis showed that COX-2 rs689465 polymorphism had a significantly independent prognostic value for OS (P = 0.017, HR = 1.637, 95% CI = 1.093-2.453).

CONCLUSION

Our study suggested that rs689465 polymorphism could be a prognostic biomarker for advanced NSCLC patients treated with first-line platinum-based chemotherapy.

Prostaglandin E-major urinary metabolite as a reliable surrogate marker for mucosal inflammation in ulcerative colitis

BACKGROUND

C-reactive protein (CRP) is used as a biomarker of ulcerative colitis (UC) activity, but CRP levels are sometimes insufficient to reflect UC activity. Therefore, a simple noninvasive biomarker assay with sufficient sensitivity and specificity to accurately reflect UC activity is desired. Since prostaglandin E2 production and colonic inflammation are associated, we evaluated whether prostaglandin E-major urinary metabolite (PGE-MUM) can be used as such a biomarker.

METHODS

Patients with UC (n = 99) were enrolled from March 2011 to February 2012. UC activity was evaluated using the simple clinical colitis activity index in 99 patients, Mayo endoscopic scoring (Mayo) in 79 patients, and Matts' grading (Matts) in 64 patients. PGE-MUM levels were measured by radioimmunoassay kit and compared against CRP levels as a control.

RESULTS

Both PGE-MUM and CRP levels correlated with UC activity (P < 0.01). Areas under the receiver operating characteristic curves of simple clinical colitis activity index, Mayo, and Matts for PEG-MUM were each higher than for CRP (0.93 > 0.73, 0.90 > 0.77, and 0.89 > 0.75, respectively). In multivariate logistic regression models, PGE-MUM was a significant independent predictor of histologic remission (sensitivity/specificity, 0.82/0.82) when the cutoff value was set to 17.0 μg/g creatinine, but CRP was not (0.69/0.69) (P < 0.01).

CONCLUSIONS

Compared with CRP level, PGE-MUM level demonstrated better sensitivity for reflecting UC activity, especially in cases of histologic inflammation, and thus seems to be a better evaluator of mucosal healing. Because this method is simple, quick, and noninvasive, PGE-MUM seems to be a useful biomarker of UC.

COX-1 (PTGS1) and COX-2 (PTGS2) polymorphisms, NSAID interactions, and risk of colon and rectal cancers in two independent populations

PURPOSE

Nonsteroidal anti-inflammatory drugs (NSAIDs) target the prostaglandin H synthase enzymes, cyclooxygenase (COX)-1 and COX-2, and reduce colorectal cancer risk. Genetic variation in the genes encoding these enzymes may be associated with changes in colon and rectal cancer risk and in NSAID efficacy.

METHODS

We genotyped candidate polymorphisms and tag SNPs in PTGS1 (COX-1) and PTGS2 (COX-2) in a population-based case–control study (Diet, Activity and Lifestyle Study, DALS) of colon cancer (n = 1,470 cases/1,837 controls) and rectal cancer (n = 583/775), and independently among cases and controls from the Colon Cancer Family Registry (CCFR; colon n = 959/1,535, rectal n = 505/839).

RESULTS

In PTGS2, a functional polymorphism (-765G[C; rs20417) was associated with a twofold increased rectal cancer risk (p = 0.05) in the DALS. This association replicated with a significant nearly fivefold increased risk of rectal cancer in the CCFR study (ORCC vs. GG = 4.88; 95 % CI 1.54–15.45; ORGC vs. GG = 1.36; 95 %CI 0.95–1.94). Genotype–NSAID interactions were observed in the DALS for PTGS1 and rectal cancer risk and for PTGS2 and colon cancer risk, but were no longer significant after correcting for multiple comparisons and did not replicate in the CCFR. No significant associations between PTGS1 polymorphisms and colon or rectal cancer risk were observed.

Meta-analysis of the association between COX-2 polymorphisms and risk of colorectal cancer based on case-control studies

OBJECTIVE

Cyclooxygenase-2 (COX-2) is an inducible enzyme converting arachidonic acid to prostaglandins and playing important roles in inflammatory diseases as well as tumor development. Previous studies investigating the association between COX-2 polymorphisms and colorectal cancer (CRC) risk reported conflicting results. We performed a meta-analysis of all available studies to explore this association.

METHODS

All studies published up to October 2013 on the association between COX-2 polymorphisms and CRC risk were identified by searching electronic databases PubMed, EMBASE, and Cochrane library. The association between COX-2 polymorphisms and CRC risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs).

RESULTS

Ten studies with 6,774 cases and 9,772 controls were included for -1195A>G polymorphism, 13 studies including 6,807 cases and 10,052 controls were available for -765G>C polymorphism, and 8 studies containing 5,121 cases and 7,487 controls were included for 8473T>C polymorphism. With respect to -765G>C polymorphism, we did not find a significant association with CRC risk when all eligible studies were pooled into the meta-analysis. However, in subgroup analyses by ethnicity and cancer location, with a Bonferroni corrected alpha of 0.05/2, statistical significant increased CRC risk was found in the Asian populations (dominant model CC+CG vs. GG: OR = 1.399, 95%CI: 1.113-1.760, P = 0.004) and rectum cancer patients (CC vs. GG: OR = 2.270, 95%CI: 1.295-3.980, P = 0.004; Recessive model CC vs. CG+GG: OR = 2.269, 95%CI: 1.297-3.970, P = 0.004). In subgroup analysis according to source of control, no significant association was detected. With respect to -1195A>G and 8473T>C polymorphisms, no significant association with CRC risk was demonstrated in the overall and subgroup analyses.

CONCLUSIONS

The present meta-analysis suggests that the COX-2 -765G>C polymorphism may be a risk factor for CRC in Asians and rectum cancer patients. Further large and well-designed studies are needed to confirm this association.

Cyclooxygenase-2 polymorphisms and susceptibility to colorectal cancer: a meta-analysis

PURPOSE

Four polymorphisms, -765G>C, -1195G>A, 8473T>C, and Val511Ala, in the cyclooxygenase-2 (COX-2) gene were identified to be associated with colorectal cancer (CRC) risk. However, the results are inconsistent. The objective of this meta-analysis was to evaluate the association between these four polymorphisms and the risk of CRC.

MATERIALS AND METHODS

All eligible case-control studies published up to December 2012 on the association between the four polymorphisms of COX-2 and CRC risk were identified by searching PubMed and Web of Science. The CRC risk associated with the four polymorphisms of the COX-2 gene was estimated for each study by odds ratio (OR) together with its 95% confidence interval (CI), respectively.

RESULTS

A total of 15 case-control studies were included. Overall, no evidence has indicated that the -1195A allele, -765C allele, 8473C allele, and 511Ala allele are associated with susceptibility to CRC (-1195G>A: OR=1.11, 95% CI: 0.82-1.51, p=0.78; -765G>C: OR=1.08, 95% CI: 0.96-1.21, p=0.07; 8473T>C: OR=1.03, 95% CI: 0.89-1.18, p=0.91; Val511Ala: OR=0.71, 95% CI: 0.46-1.09, p=0.94). However, stratified analysis with ethnicity indicated that individuals with -765GC or GC/CC genotypes had an increased risk of CRC among Asian populations (GC vs. GG: OR=1.05, 95% CI: 0.87-1.28, p=0.03; GC+CC vs. GG: OR=1.08, 95% CI: 0.96-1.21, p=0.07).

CONCLUSION

This meta-analysis indicated that -765G>C polymorphism was significantly associated with susceptibility to CRC in Asian populations.

COX-2-765G>C polymorphism increases the risk of cancer: a meta-analysis

Background

Chronic inflammation has been regarded as an important mechanism in carcinogenesis. Inflammation-associated genetic variants have been highly associated with cancer risk. Polymorphisms in the gene cyclooxygenase-2 (COX-2), a pro-inflammation factor, have been suggested to alter the risk of multiple tumors, but the findings of various studies are not consistent.

Methods

A literature search through February 2013 was performed using PubMed, EMBASE, and CNKI databases. We used odds ratios (ORs) with confidence intervals (CIs) of 95% to assess the strength of the association between the COX-2-765G>C polymorphism and cancer risk in a random-effect model. We also assessed heterogeneity and publication bias.

Results

In total, 65 articles with 29,487 cancer cases and 39,212 non-cancer controls were included in this meta-analysis. The pooled OR (95% CIs) in the co-dominant model (GC vs. GG) was 1.11 (1.02–1.22), and in the dominant model ((CC+GC) vs. GG), the pooled OR was 1.12 (1.02–1.23). In the subgroup analysis, stratified by cancer type and race, significant associations were found between the-765 C allele and higher risk for gastric cancer, leukemia, pancreatic cancer, and cancer in the Asian population.

Conclusion

In summary, the COX-2-765 C allele was related to increased cancer susceptibility, especially gastric cancer and cancer in the Asian population.

The association between COX-2 polymorphisms and hematologic toxicity in patients with advanced non-small-cell lung cancer treated with platinum-based chemotherapy

Background and Objective

Overexpression of COX-2 is proved to contribute to tumor promotion and carcinogenesis through stimulating cell proliferation, inhibiting apoptosis and enhancing the invasiveness of cancer cells. Apoptosis-related molecules are potential predictive markers for survival and toxicity in platinum treatment. This study aimed at investigating the association between COX-2 polymorphisms and the occurrence of grade 3 or 4 toxicity in advanced non–small cell lung cancer patients treated with platinum-based chemotherapy.

Materials and Methods

Two hundred and twelve patients with inoperable stage IIIB-IV NSCLC received first-line chemotherapy between 2007 and 2009 were recruited in this study. Four functional COX-2 polymorphisms were genotyped by PCR-based restriction fragment length polymorphism (RFLP) methods.

Results

The incidence of grade 3 or 4 hematologic toxicity was significantly higher in G allele carriers of the COX-2 rs689466 (−1195G/A) polymorphism compared with wild-type homozygotes AA (P value = 0.008; odds ratio, 2.47; 95% confidence internal, 1.26–4.84) and the significance still existed after the Bonferroni correction. Statistically significant difference was also found in grade 3 or 4 leukopenia (P value = 0.010; OR = 2.82; 95%CI = 1.28–6.20). No other significant association was observed between genotype and toxicity in the study. The haplotype analysis showed that the haplotype AGG was associated with a reduced risk of grade 3 or 4 hematologic and leukopenia toxicity (P value = 0.009; OR = 0.59; 95%CI = 0.39–0.88 and P value = 0.025; OR = 0.61; 95%CI = 0.39–0.94, respectively) while the haplotype GGG was associated with an increased risk of grade 3 or 4 hematologic and leukopenia toxicity (P value = 0.009; OR = 1.71; 95%CI = 1.14–2.56 and P value = 0.025; OR = 1.65; 95%CI  = 1.06–2.57, respectively).

Conclusion

This investigation for the first time suggested that polymorphism in COX-2 rs689466 may be a potent bio-marker in predicting severe hematologic toxicity in NSCLC patients after platinum-based chemotherapy.

Prognostic role of host cyclooxygenase and cytokine genotypes in a Caucasian cohort of patients with gastric adenocarcinoma

BACKGROUND

Genetic factors influencing the prognosis of gastric adenocarcinoma (GAC) are not well known. Given the relevance of cytokines and other pro-inflammatory mediators in cancer progression and invasiveness, we aimed to assess the prognostic role of several functional cytokine and cyclooxygenase gene polymorphisms in patients with GAC.

METHODOLOGY

Genomic DNA from 380 Spanish Caucasian patients with primary GAC was genotyped for 23 polymorphisms in pro-inflammatory (IL1B, TNFA, LTA, IL6, IL12p40), anti-inflammatory (IL4, IL1RN, IL10, TGFB1) cytokine, and cyclooxygenase (PTGS1 and PTGS2) genes by PCR, RFLP and TaqMan assays. Clinical and histological information was collected prospectively. Survival curves were estimated by the Kaplan-Meier method and compared using the log rank test. Outcome was determined by analysis of Cox proportional hazards, adjusting for confounding factors.

RESULTS

The median follow-up period and median overall survival (OS) time were 9.9 months (range 0.4-120.3) and 10.9 months (95% CI: 8.9-14.1), respectively. Multivariate analysis identified tumor stages III (HR, 3.23; 95% CI:2-5.22) and IV (HR, 5.5; 95% CI: 3.51-8.63) as independent factors associated with a significantly reduced OS, whereas surgical treatment (HR: 0.44; 95%CI: 0.3-0.6) was related to a better prognosis of the disease. Concerning genetic factors, none of the 23 polymorphisms evaluated in the current study did influence survival. Moreover, no gene-environment interactions on GAC prognosis were observed.

CONCLUSIONS

Our results show that, in our population, the panel of selected pro- and anti-inflammatory cytokine, and cyclooxygenase gene polymorphisms are not relevant in determining the prognosis of gastric adenocarcinoma.

Association between colorectal cancer susceptibility loci and survival time after diagnosis with colorectal cancer

Genome-wide association studies have identified 16 germline single-nucleotide polymorphisms (SNPs) that are associated with colorectal cancer (CRC) incidence. We examined the relationship between these SNPs and survival of 2611 individuals with CRC, enrolled in 5 cohort studies. We used Cox regression analysis to associate SNPs with overall and CRC-specific survival times. The minor allele in rs4939827 (SMAD7) was associated with reduced overall survival (hazard ratio, 1.16; 95% confidence interval, 1.06-1.27; P = .002) and disease-specific survival (hazard ratio, 1.17; 95% confidence interval, 1.05-1.30; P = .005). Other SNPs were not associated significantly with survival. Common germline variations might be prognostic factors for patients with CRC. A variant in SMAD7 could affect progression of CRC.

PTGS2 (COX2) -765G>C gene polymorphism and risk of sporadic colorectal cancer in Iranian population

Colorectal cancer (CRC) is one of the leading cancers worldwide. Through genome wide association studies, several single nucleotide polymorphisms scattered in the genome emerged to be influential in the development of sporadic CRC in some populations. However, replicative studies failed to prove a particular SNP-CRC association in populations and ethnic groups. Cyclooxygenase-2 (PTGS2) is a crucial enzyme involved in the metabolism of prostaglandins. The aim of this replicative study is to investigate the possible association between PTGS2 -765G>C polymorphism and sporadic CRC risk in a subset of Iranian population. A total of 110 patients with sporadic CRC, and 120 controls were genotyped for PTGS2 -765G>C polymorphism by using polymerase chain reaction-based restriction fragment length polymorphism. There were no significant differences in the genotype and allele frequencies of PTGS2 -765G>C between two groups except in irregular aspirin or non-steroidal anti-inflammatory drugs (NSAID) consumers. Frequencies of genotypes and alleles were as follows: GG = 44.2, GC = 48.3, CC = 7.5%, in controls and GG = 34.55, GC = 60.9, CC = 4.55% in cases. Regarding the allele frequency, the following values were found: G = 65, C = 35% in cases and 68.3, 31.7% in the controls, respectively. In irregular aspirin or NSAID consumers combined GC+CC genotype was found to be a risk genotype (OR = 1.933, 95% CI: 1.067-3.501, P = 0.036). Overall, no significant relation was found between this polymorphism and sporadic CRC in Iranians. However, in irregular aspirin or NSAID consumers the combined GC+CC genotype proved to be a risk genotype.

Genetic variation in inflammatory pathways is related to colorectal cancer survival

PURPOSE

Prognosis of patients with colorectal cancer (CRC) is associated with systemic inflammation, and anti-inflammatory drugs can reduce both CRC incidence and mortality. Genetic variation in proinflammatory pathways can affect an individual's CRC risk. However, few studies have investigated the prognostic importance of this genetic variation in CRC patients.

EXPERIMENTAL DESIGN

We investigated the association between CRC survival and genetic variation in proinflammatory pathways among patients from the Puget Sound Surveillance Epidemiology and End Results registry. Single-nucleotide polymorphisms were genotyped in five genes (PTGS-1, PTGS-2, MRP4, NFκB, and IκBKβ). Vital status was ascertained through linkage to the National Death Index. Cox proportional hazards regression was used to calculate HRs and 95% confidence intervals (CI). The false discovery rate method of Benjamini and Hochberg was applied to address multiple testing.

RESULTS

Four PTGS-1 variants were associated with CRC survival. One, G>A intron 9 (rs1213266), was associated with approximately 50% lower CRC mortality (HR(AA/AG vs. GG) = 0.48; 95% CI, 0.25-0.93). Three variants, including L237M, resulted in significantly elevated CRC mortality risk, with HRs ranging from approximately 1.5 to 2.0. Two variants in IκBKβ, including R526Q, were significantly associated with CRC survival. Correction for multiple testing indicated that variants in both PTGS-1 and IκBKβ are reproducibly associated with CRC survival.

CONCLUSION

Our findings suggest that genetic variation in proinflammatory pathways may be important for CRC prognosis. This investigation represents one of the first descriptions of the relationship between inherited polymorphisms and mortality in CRC patients and provides a starting point for further research.

Epstein-Barr virus-specific methylation of human genes in gastric cancer cells

Background

Epstein-Barr Virus (EBV) is found in 10% of all gastric adenocarcinomas but its role in tumor development and maintenance remains unclear. The objective of this study was to examine EBV-mediated dysregulation of cellular factors implicated in gastric carcinogenesis.

Methods

Gene expression patterns were examined in EBV-negative and EBV-positive AGS gastric epithelial cells using a low density microarray, reverse transcription PCR, histochemical stains, and methylation-specific DNA sequencing. Expression of PTGS2 (COX2) was measured in AGS cells and in primary gastric adenocarcinoma tissues.

Results

In array studies, nearly half of the 96 human genes tested, representing 15 different cancer-related signal transduction pathways, were dysregulated after EBV infection. Reverse transcription PCR confirmed significant impact on factors having diverse functions such as cell cycle regulation (IGFBP3, CDKN2A, CCND1, HSP70, ID2, ID4), DNA repair (BRCA1, TFF1), cell adhesion (ICAM1), inflammation (COX2), and angiogenesis (HIF1A). Demethylation using 5-aza-2'-deoxycytidine reversed the EBV-mediated dysregulation for all 11 genes listed here. For some promoter sequences, CpG island methylation and demethylation occurred in an EBV-specific pattern as shown by bisulfite DNA sequencing. Immunohistochemistry was less sensitive than was western blot for detecting downregulation of COX2 upon EBV infection. Virus-related dysregulation of COX2 levels in vitro was not recapitulated in vivo among naturally infected gastric cancer tissues.

Conclusions

EBV alters human gene expression in ways that could contribute to the unique pathobiology of virus-associated cancer. Furthermore, the frequency and reversability of methylation-related transcriptional alterations suggest that demethylating agents have therapeutic potential for managing EBV-related carcinoma.

MGMT promoter methylation, loss of expression and prognosis in 855 colorectal cancers

OBJECTIVE

O⁶-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme. MGMT promoter hypermethylation and epigenetic silencing often occur as early events in carcinogenesis. However, prognostic significance of MGMT alterations in colorectal cancer remains uncertain.

METHODS

Utilizing a database of 855 colon and rectal cancers in two prospective cohort studies (the Nurses' Health Study and the Health Professionals Follow-up Study), we detected MGMT promoter hypermethylation in 325 tumors (38%) by MethyLight and loss of MGMT expression in 37% (247/672) of tumors by immunohistochemistry. We assessed the CpG island methylator phenotype (CIMP) using eight methylation markers [CACNA1G, CDKN2A (p16), CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1], and LINE-1 (L1) hypomethylation, TP53 (p53), and microsatellite instability (MSI).

RESULTS

MGMT hypermethylation was not associated with colorectal cancer-specific mortality in univariate or multivariate Cox regression analysis [adjusted hazard ratio (HR) = 1.03; 95% confidence interval (CI), 0.79-1.36] that adjusted for clinical and tumor features, including CIMP, MSI, and BRAF mutation. Similarly, MGMT loss was not associated with patient survival. MGMT loss was associated with G>A mutations in KRAS (p = 0.019) and PIK3CA (p = 0.0031).

CONCLUSIONS

Despite a well-established role of MGMT aberrations in carcinogenesis, neither MGMT promoter methylation nor MGMT loss serves as a prognostic biomarker in colorectal cancer.

Tumor-associated Macrophages (TAM) and Inflammation in Colorectal Cancer

Experimental and epidemiological studies indicate a strong link between chronic inflammation and tumor progression. Human colorectal cancer (CRC), a major cause of cancer-related death in Western countries, represents a paradigm for this link. Key features of cancer-related inflammation in CRC are the activation of transcription factors (e.g. NF-κB, STAT3), the expression of inflammatory cytokines and chemokines (e.g. TNFα, IL-6, CCL2, CXCL8) as well as a prominent leukocyte infiltrate. While considerable evidence indicates that the presence of lymphocytes of adaptive immunity may positively influence patient survival and clinical outcome in CRC, the role of tumor-associated macrophages (TAM) and of other lymphoid populations (e.g. Th17, Treg) is still unclear. In this review we will summarize the different and controversial effects that TAM play in CRC-related inflammation and progression of disease. The characterization of the most relevant inflammatory pathways in CRC is instrumental for the identification of new target molecules that could lead to improved diagnosis and treatment.

Potentially functional COX-2-1195G>A polymorphism increases the risk of digestive system cancers: a meta-analysis

BACKGROUND AND AIM

Three potentially functional polymorphisms: -765G>C, -1195G>A, and 8473T>C in the cyclooxygenase-2 (COX-2) gene were identified and proposed to be associated with cancer susceptibility. The aim of this meta-analysis was to evaluate the association between these three polymorphisms and the risk of cancer in diverse populations.

METHODS

All case-control studies published up to November 2009 on the association between the three polymorphisms of COX-2 and cancer risk were identified by searching PubMed. The cancer risk associated with the three polymorphisms of the COX-2 gene was estimated for each study by OR together with its 95% confidence interval (CI), respectively.

RESULTS

A total of 47 case-control studies were included, and variant genotypes GA/AA of -1195G>A were associated with a significantly increased cancer risk (GA/AA vs GG: odds ratio [OR], 1.29; 95% CI, 1.18-1.41; P(heterogeneity) = 0.113), and this significant association was mainly observed within cancers of the digestive system (e.g. colorectal, gastric, esophageal, oral, biliary tract, gallbladder, and pancreatic) without between-study heterogeneity (GA/AA vs GG: OR, 1.36; 95% CI; 1.23-1.51; P(heterogeneity) = 0.149). Furthermore, a stratification analysis showed that the risk of COX-2-1195G>A associated with cancers in the digestive system was more evident among Asians than Caucasians. However, for COX-2-765G>C and 8473T>C, no convincing association between the two polymorphisms and risk of cancer or cancer type was observed.

CONCLUSIONS

The effect of three potentially functional polymorphisms (-765G>C, -1195G>A, and 8473T>C) in the COX-2 gene on cancer risk provided evidence that the COX-2-1195G>A polymorphism was significantly associated with increased risk of digestive system cancers, especially among Asian populations.

Cyclooxygenase-2 genetic variants are associated with survival in unresectable locally advanced non-small cell lung cancer

PURPOSE

Cyclooxygenase-2 (COX-2) plays important roles in the modulation of apoptosis, angiogenesis, immune response, and tumor invasion. Elevated COX-2 expression has been reported to be correlated with reduced survival after radiotherapy. This study examined whether genetic variations in the COX-2 gene are associated with different survival in inoperable locally advanced non-small cell lung cancer (NSCLC) treated with chemoradiotherapy or radiotherapy alone.

EXPERIMENTAL DESIGN

One hundred and thirty-six patients with inoperable stage IIIA-B NSCLC receiving thoracic irradiation between 2004 and 2007 were recruited in this study. Five functional COX-2 polymorphisms were genotyped using DNA from blood lymphocytes. Kaplan-Meier methods were used to compare survival by different genotypes. Cox proportional hazards models were used to identify independently significant variables.

RESULTS

During the median 22.4 months of follow-up, the favorable COX-2 -1195GA and GG genotypes were significantly correlated with better overall survival (20.2 months versus 15.7 months; P = 0.006; hazard ratio (HR), 0.58; 95% confidence interval (CI), 0.39-0.86) and with longer progress-free survival (11.9 months versus 9.5 months; P = 0.034) compared with the -1195AA genotype. No significant associations were found among other COX-2 polymorphisms and clinical outcomes. In the multivariate Cox proportional hazards model, COX-2 -1195G/A polymorphism was independently associated with overall survival after adjusting the clinicopathologic factors (P = 0.008; HR, 0.58; 95% CI, 0.39-0.87).

CONCLUSION

COX-2 -1195G/A polymorphism is a potential predictive marker of survival in locally advanced NSCLC patients treated with chemoradiotherapy or radiotherapy alone.