COX-2 Polymorphism, Use of Nonsteroidal Anti-Inflammatory Drugs, and Risk of Colon Cancer in African Americans (United States)

Non-aspirin non-steroidal anti-inflammatory drugs in prevention of colorectal cancer in people aged 40 or older: A systematic review and meta-analysis

There is still insufficient data about the risk-benefit profile about recommending non-aspirin, non-steroidal anti-inflammatory drugs (NA-NSAIDs) for colorectal cancer (CRC) prevention, especially in people aged 40 years or older. This study specifically addressed the association between regular NA-NSAIDs use and CRC risk in the population aged 40 years or older, performing a comprehensive systematic review and meta-analysis of all published studies on this topic until April 2018, by a search of PubMed, Scopus and Web of science databases and clinical trial registries. Two reviewers independently selected studies based on predefined inclusion criteria and assessed study quality using the Newcastle-Otawa scale. The data was combined with the random effects model. Potential heterogeneity was calculated as Q statistic and I² value. A total of 23 studies involving more than 1 million subjects contributed to the analysis. Pooled odds ratio (OR) of NA-NSAIDs effects on CRC risk was 0.74 (0.67-0.81), I² = 75.9%, p < 0.001. Heterogeneity was explained by a number of variables including the quality of the studies. Significant protective effects of NA-NSAIDs use were found for women (risk reduction of 19%), higher doses (risk reduction of 18%), distal colon cancer (risk reduction of 22%) and white people (risk reduction from 31% to 41%). From the results NA-NSAIDs use appears to be CRC chemopreventive for a specific subgroup of the population.

POLYMORPHISM OF THE COX-2 GENE AND SUSCEPTIBILITY TO COLON AND RECTAL CANCER

Background:

The colorectal neoplasm is the fourth most common malignancy among males and the third among females. In the Western world is estimated that 5% of the population will develop it, making this disease a major public health problem.

Aim:

To analyze the prevalence of the polymorphism -765G / C region of the COX-2 gene in colorectal cancer patients compared to a control group, analyzing the possible association between this polymorphism and susceptibility to colorectal cancer.

Method:

This is a case-control study with 85 participants. Were selected 25 with colorectal cancer (case group) and 60 participants without colorectal neoplasia (control group). The molecular genetic analysis was perform to identify the polymorphism -765G / C COX2 gene with standard literature technique. In addition, patient’s clinical and pathological data were analyzed.

Results:

There was a light increase in prevalence between men in the case group, although this difference was not statistically significant. The results showed a high prevalence of GC and CC genotype in individuals with colorectal cancer, demonstrating an association between the presence of the polymorphism in the COX2 gene and susceptibility to colorectal cancer in this pattern (p=0.02). Similarly, there was also difference in allele frequencies in the groups. When patients with cancer were separated by tumor location, there was a higher prevalence of polymorphism in the left colon (p=0.02).

Conclusion:

The polymorphism in the COX2 gene is associated with increased susceptibility to colorectal cancer, specially rectosigmoid tumors.

Adenomas - Genetic factors in colorectal cancer prevention

Colorectal cancer is the second most common type of cancer both in Europe and Poland. During the last 30 years more than a 3-fold increase has been observed in Poland due to environmental and genetic factors. Almost all colorectal malignancies are related to the formation and malignant transformation of colorectal dysplasia and adenoma. Efforts aiming to decrease the number of colorectal cancer deaths are focused on the disease early detection. Genetic diagnosis for hereditary syndromes predisposing to colorectal cancer has been developed and is a part of the routine treatment. Most cancers are sporadic. They often develop from polyps in the colon. In addition to the genetic events described in the 1990s, showing the adenoma transformation into carcinoma that has been a prime example of malignant transformation for a long time, there are also other possibilities of neoplastic transformation. The recognition of colorectal cancer risk factors make sense as their nature is lifestyle- and diet-related. In this review paper those risk factors are presented and the prevention of colorectal cancer is discussed taking into account genetic factors.

Cyclooxygenase-2 gene polymorphisms and susceptibility to colorectal cancer in a Brazilian population

BACKGROUND

Multi-ethnicity of Brazilian population displays high levels of genomic diversity. Polymorphism may detect people at higher risk of developing cancer, distinctive response to treatment, and prognosis. Cyclooxygenase-2 (COX-2) is induced in response to growth factors and cytokines, and is expressed in inflammatory diseases, precancerous lesions and colorectal cancer (CRC). The aim of this study was to evaluate the influence of COX-2 -1195A > G and 8473T > C polymorphisms as a risk factor of developing CRC.

METHODS

We evaluated COX-2 Single Nucleotide Polymorphism (SNP) of 230 CRC patients and 196 healthy controls by Real-Time Polymerase Chain Reaction.

RESULTS

Populations were in Hardy-Weinberg equilibrium (HWE), except for control group of 8473T > C SNP. The frequencies were similar in both groups for genotypes and haplotypes. There was no association between studied polymorphisms and risk of CRC.

CONCLUSIONS

The gene polymorphisms studied do not participate in the genetic susceptibility to CRC in a Brazilian population.

Pharmacogenetics of analgesic drugs

• Individual variability in pain perception and differences in the efficacy of analgesic drugs are complex phenomena and are partly genetically predetermined.

• Analgesics act in various ways on the peripheral and central pain pathways and are regarded as one of the most valuable but equally dangerous groups of medications.

• While pharmacokinetic properties of drugs, metabolism in particular, have been scrutinised by genotype–phenotype correlation studies, the clinical significance of inherited variants in genes governing pharmacodynamics of analgesics remains largely unexplored (apart from the µ-opioid receptor).

• Lack of replication of the findings from one study to another makes meaningful personalised analgesic regime still a distant future.

• This narrative review will focus on findings related to pharmacogenetics of commonly used analgesic medications and highlight authors’ views on future clinical implications of pharmacogenetics in the context of pharmacological treatment of chronic pain.

Cyclooxygenase-2 gene polymorphisms and the risk of colorectal cancer: A population-based study

The aim of the present study was to determine the association between polymorphisms in the cyclooxygenase-2 (COX-2) gene promoter region, rs20417 G/C and rs2745557 G/A, and the susceptibility to colorectal cancer (CRC) in a Han Chinese population in Shaanxi, China. Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) were used to detect the polymorphisms of COX-2, rs20417 G/C and rs2745557 G/A, in 300 patients with CRC and 300 healthy individuals in the present case-control study. The results revealed that for the COX-2 rs20417 G/C polymorphism, the GC+CC allele frequency was 80% in CRC patients and 71% in healthy controls [odds ratio (OR)=1.63; 95% confidence interval (CI), 1.12-2.38; P=0.01]. For the COX-2 rs2745557 G/A polymorphism, the GA+AA allele frequency was 84% in CRC patients and 73% in healthy controls (OR=1.94; 95% CI, 1.30-2.90; P<0.01). In addition, among individuals with a smoking history, drinking history or family history of CRC, those who were COX-2 rs20417 (GC+CC) or COX-2 rs2745557 (GA+AA) carriers had a significantly increased risk of developing CRC compared with that of GG genotype carriers (P<0.05). Furthermore, the allelic frequencies of COX-2 rs20417 G/C and rs2745557 G/A in patients with lymph node metastasis in stage III/IV of CRC were significantly different from those of COX-2 rs20417 G/C and rs2745557 G/A in patients without lymph node metastasis in stage I/II (P<0.05). In conclusion, the results of the present study revealed that COX-2 rs20417 C allele carriers and rs2745557 A allele carriers have a significantly increased risk of CRC compared with GG genotype carriers; in addition, the frequencies of these alleles were demonstrated to be associated with lymph node metastasis and CRC progression.

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.

Systematic review: interactions between aspirin, and other nonsteroidal anti-inflammatory drugs, and polymorphisms in relation to colorectal cancer

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) include aspirin (acetylsalicylic acid, ASA). Long-term use of NSAIDs has been associated with lowered risk of colorectal cancer (CRC), but the use is hampered by adverse effects. Also, the anti-carcinogenic effects of NSAIDs are incompletely understood. Understanding biological effects of NSAIDs may help developing new preventive medical strategies.

AIM

To identify gene-environment interactions between genetic variation and NSAID use in relation to risk of CRC.

METHODS

We performed a PubMed literature search and all studies reporting original data on interactions between NSAIDs and polymorphisms in relation to CRC were evaluated.

RESULTS

We found indications that aspirin interacted with rs6983267 close to MYC (encoding a transcription factor involved in cell cycle progression, apoptosis and cellular transformation) and NSAIDs interacted with rs3024505 and rs1800872 in or close to IL10 (encoding IL-10) in preventing CRC. Homozygous carriers of the variant allele of rs6983267 (ca. 25% of the population) halved their risk for CRC by aspirin use compared to homozygous wildtype carriers who did not benefit from aspirin intake. No interaction between use of NSAIDs and PTGS-2 (encoding COX-2) in relation to CRC risk was detected. Other findings of interactions between genes in inflammatory and oncogenic pathways and NSAIDs were considered suggestive.

CONCLUSIONS

Knowledge of underlying biological effects of NSAIDs in relation to CRC is scarce and the basis for stratifying the patients for preventive treatment is not yet available. Further studies assessing interactions between long-term NSAID exposure and genetic variation in relation to CRC are warranted in large well-characterised prospective cohorts.

Polymorphisms in arachidonic acid metabolism-related genes and the risk and prognosis of colorectal cancer

Cyclooxygenase-2 (COX-2), 12-lipoxygenase (12-LOX) and phospholipaseA2 (PLA2) played important roles in the modulation of apoptosis, angiogenesis, carcinogenesis and invasion of colorectal cancer (CRC). The polymorphisms in COX-2, 12-LOX and PLA2 may affect their roles. Therefore, we investigated if COX-2 -1195G > A, 12-LOX 261Arg > Gln and PLA2 c.349 + 191A > G polymorphisms were associated with risk and prognosis of CRC as well as possible interactions with the environmental factors on the risk of CRC in Northeast of China. A case-control study with 451 cases and 631 controls were carried out, a cohort with 386 patients were followed up. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Compared with the 261Arg/Arg genotype, 12-LOX 261Arg/Gln genotype and 261Arg/Gln + Gln/Gln genotypes reduced the risk of rectal cancer by 33% (adjusted OR = 0.67, 95% CI 0.47-0.97, p = 0.03) and 32% (adjusted OR = 0.68, 95% CI 0.49-0.96, p = 0.03), respectively. The adjusted HR for the association between 12-LOX 261Gln/Gln genotype and overall survival in patients with CRC was 1.68 (95% CI 1.06-2.68, p = 0.03). There was also evidence of an interaction between the PLA2 c.349 + 191 A > G genotypes and the overnight food consumption (adjusted ORi = 1.92, 95% CI 1.14-3.25, P(interaction) = 0.01). These observations indicate that 12-LOX 261Arg > Gln polymorphism may affect risk of rectal cancer, and it may be a potential predictive marker for prognosis of CRC.

Shared and independent colorectal cancer risk alleles in TGFβ-related genes in African and European Americans

Genome-wide association studies (GWAS) in colorectal cancer (CRC) identified five regions near transforming growth factor β-related genes BMP4, GREM1, CDH1, SMAD7 and RPHN2. The true risk alleles remain to be identified in these regions, and their role in CRC risk in non-European populations has been understudied. Our previous work noted significant genetic heterogeneity between African Americans (AAs) and European Americans (EAs) for single nucleotide polymorphisms (SNPs) identified in GWAS. We hypothesized that associations may not have been replicated in AAs due to differential or independent genetic structures. In order to test this hypothesis, we genotyped 195 tagging SNPs across these five gene regions in 1194 CRC cases (795 AAs and 399 EAs) and 1352 controls (985 AAs and 367 EAs). Imputation was performed, and association testing of genotyped and imputed SNPs included ancestry, age and sex as covariates. In two of the five genes originally associated with CRC, we found evidence for association in AAs including rs1862748 in CDH1 (OR(Add) = 0.82, P = 0.02) and in GREM1 the SNPs rs10318 (OR(Rec) = 60.1, P = 0.01), rs11632715 (OR(Rec) = 2.36; P = 0.004) and rs12902616 (OR(Rec) = 1.28, P = 0.005), the latter which is in linkage disequilibrium with the previously identified SNP rs4779584. Testing more broadly for associations in these gene regions in AAs, we noted three statistically significant association peaks in GREM1 and RHPN2 that were not identified in EAs. We conclude that some CRC risk alleles are shared between EAs and AAs and others are population specific.

Genetic variation in vitamin D-related genes and risk of colorectal cancer in African Americans

Purpose

Disparities in both colorectal cancer (CRC) incidence and survival impact African Americans (AAs) more than other US ethnic groups. Because vitamin D is thought to protect against CRC and AAs have lower serum vitamin D levels, genetic variants that modulate the levels of active hormone in the tissues could explain some of the cancer health disparity. Consequently, we hypothesized that genetic variants in vitamin D-related genes are associated with CRC risk.

Methods

To test this hypothesis, we studied 39 potentially functional single-nucleotide polymorphisms (SNPs) in eight genes (CYP2R1, CYP3A4, CYP24A1, CYP27A1, CYP27B1, GC, DHCR7, and VDR) in 961 AA CRC cases and 838 healthy AA controls from Chicago and North Carolina. We tested whether SNPs are associated with CRC incidence using logistic regression models to calculate p values, odds ratios, and 95 % confidence intervals. In the logistic regression, we used a log-additive genetic model and used age, gender, and percent West African ancestry, which we estimated with the program STRUCTURE, as covariates in the models.

Results

A nominally significant association was detected between CRC and the SNP rs12794714 in the vitamin D 25-hydroxylase gene CYP2R1 (p = 0.019), a SNP that has previously been associated with serum vitamin D levels. Two SNPs, rs16847024 in the GC gene and rs6022990 in the CYP24A1 gene, were nominally associated with left-sided CRC (p = 0.015 and p = 0.018, respectively).

Conclusions

Our results strongly suggest that genetic variation in vitamin D-related genes could affect CRC susceptibility in AAs.

Electronic supplementary material

The online version of this article (doi:10.1007/s10552-014-0361-y) contains supplementary material, which is available to authorized users.

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.

Genetic associations in the vitamin D receptor and colorectal cancer in African Americans and Caucasians

Low vitamin D levels are associated with an increased incidence of colorectal cancer (CRC) and higher mortality from the disease. In the US, African Americans (AAs) have the highest CRC incidence and mortality and the lowest levels of vitamin D. Single nucleotide polymorphisms (SNPs) in the vitamin D receptor (VDR) gene have been previously associated with CRC, but few studies have included AAs. We studied 795 AA CRC cases and 985 AA controls from Chicago and North Carolina as well as 1324 Caucasian cases and 990 Caucasian controls from Chicago and Spain. We genotyped 54 tagSNPs in VDR (46586959 to 46521297 Mb) and tested for association adjusting for West African ancestry, age, gender, and multiple testing. Untyped markers were imputed using MACH1.0. We analyzed associations by gender and anatomic location in the whole study group as well as by vitamin D intake in the North Carolina AA group. In the joint analysis, none of the SNPs tested was significantly associated with CRC. For four previously tested restriction fragment length polymorphisms, only one (referred to as ApaI), tagged by the SNP rs79628898, had a nominally significant p-value in AAs; none of these polymorphisms were associated with CRC in Caucasians. In the North Carolina AAs, for whom we had vitamin D intake data, we found a significant association between an intronic SNP rs11574041 and vitamin D intake, which is evidence for a VDR gene-environment interaction in AAs. In summary, using a systematic tagSNP approach, we have not found evidence for significant associations between VDR and CRC in AAs or Caucasians.

Hematopoietic prostaglandin D synthase (HPGDS): a high stability, Val187Ile isoenzyme common among African Americans and its relationship to risk for colorectal cancer

Intestinal tumors in Apc(Min/+) mice are suppressed by over-production of HPGDS, which is a glutathione transferase that forms prostaglandin D(2) (PGD(2)). We characterized naturally occurring HPGDS isoenzymes, to see if HPGDS variation is associated with human colorectal cancer risk. We used DNA heteroduplex analysis and sequencing to identify HPGDS variants among healthy individuals. HPGDS isoenzymes were produced in bacteria, and their catalytic activities were tested. To determine in vivo effects, we conducted pooled case-control analyses to assess whether there is an association of the isoenzyme with colorectal cancer. Roughly 8% of African Americans and 2% of Caucasians had a highly stable Val187lle isoenzyme (with isoleucine instead of valine at position 187). At 37°C, the wild-type enzyme lost 15% of its activity in 1h, whereas the Val187Ile form remained >95% active. At 50°C, the half life of native HPGDS was 9min, compared to 42 min for Val187Ile. The odds ratio for colorectal cancer among African Americans with Val187Ile was 1.10 (95% CI, 0.75-1.62; 533 cases, 795 controls). Thus, the Val187Ile HPGDS isoenzyme common among African Americans is not associated with colorectal cancer risk. Other approaches will be needed to establish a role for HPGDS in occurrence of human intestinal tumors, as indicated by a mouse model.

A new cyclo-oxygenase-2 gene variant in the Han Chinese population is associated with an increased risk of gastric carcinoma

BACKGROUND AND OBJECTIVE

Cyclo-oxygenase-2 (COX-2, also known as prostaglandin synthase 2) influences carcinogenesis through regulation of angiogenesis, apoptosis, and cytokine expression. COX-2 is encoded by the gene PTGS2. Several studies have suggested that PTGS2 single-nucleotide polymorphisms (SNPs) are involved in gastrointestinal carcinogenesis. In this study, we observed the PTGS2 Val511Ala (5939T/C) polymorphism in the Chinese population for the first time, and investigated whether this polymorphism might contribute to gastric cancer in a case-control study conducted in the Gansu province of China, a high-risk area for gastric cancer.

METHODS

We determined the genotypes of 110 gastric cancer patients and 138 controls using polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) analysis. Data were statistically analyzed using a chi-squared test and a logistic regression model.

RESULTS AND CONCLUSION

In our analysis, PTGS2 5939C allele carriers were at increased risk of gastric cancer (odds ratio [OR] 1.742; 95% confidence interval [CI] 1.009, 3.005; p = 0.045). We also found an interaction between Helicobacter pylori infection, a family history of gastric cancer, and presence of the 5939C allele. This study further indicated that H. pylori-positive status and family history jointly contribute to a higher risk of gastric cancer.

Interactions among genes, tumor biology and the environment in cancer health disparities: examining the evidence on a national and global scale

Cancer incidence and mortality rates show great variations across nations and between population groups. These variations are largely explained by differences in age distribution, diet and lifestyle, access to health care, cultural barriers and exposure to carcinogens and pathogens. Cancers caused by infections are significantly more common in developing than developed countries, and they overproportionally affect immigrant populations in the USA and other countries. The global pattern of cancer is not stagnant. Instead, it is dynamic because of fluctuations in the age distribution of populations, improvements in cancer prevention and early detection in affluent countries and rapid changes in diet and lifestyle in parts of the world. For example, increased smoking rates have caused tobacco-induced cancers to rise in various Asian countries, whereas reduced smoking rates have caused these cancers to plateau or even begin to decline in Western Europe and North America. Some population groups experience a disproportionally high cancer burden. In the USA and the Caribbean, cancer incidence and mortality rates are excessively high in populations of African ancestry when compared with other population groups. The causes of this disparity are multifaceted and may include tumor biological and genetic factors and their interaction with the environment. In this review, we will discuss the magnitude and causes of global cancer health disparities and will, with a focus on African-Americans and selected cancer sites, evaluate the evidence that genetic and tumor biological factors contribute to existing cancer incidence and outcome differences among population groups in the USA.

Genetic heterogeneity in colorectal cancer associations between African and European americans

BACKGROUND & AIMS

Genome-wide association studies of colorectal cancer (CRC) have identified risk variants in 10 genomic regions. None of these studies included African Americans, who have the highest incidence and mortality from CRC in the United States. For the 10 genomic regions, we performed an association study of Americans of African and European descent.

METHODS

We genotyped 22 single nucleotide polymorphisms (SNPs) in DNA samples from 1194 patients with CRC (795 African Americans and 399 European Americans) and 1352 controls (985 African Americans and 367 European Americans). At chromosome 8q24.21 region 3, we analyzed 6 SNPs from 1000 African American cases and 1393 controls. Association testing was done using multivariate logistic regression controlling for ancestry, age, and sex.

RESULTS

Among African Americans, the SNP rs6983267 at 8q24.21 was not associated with CRC (odds ratio, 1.18; P = .12); instead, the 8q24.21 SNP rs7014346 (odds ratio, 1.15; P = .03) was associated with CRC in this population. At 15q13.3, rs10318 was associated with CRC in both populations. At 11q23.1, rs3802842 was significantly associated with rectal cancer risk only among African Americans (odds ratio, 1.34; P = .01); this observation was made in previous studies. Among European Americans, SNPs at 8q24.21, 11q23.1, and 16q22.1 were significantly associated with CRC, and the odds ratios were of the same magnitude and direction for all SNPs tested, consistent with previously published studies. In contrast, in African Americans, the opposite allele of rs10795668 at 10p14 was associated with colorectal cancer (odds ratio, 1.35; P = .04), and altogether the odds ratios were in the opposite direction for 9 of the 22 SNPs tested.

CONCLUSIONS

There is genetic heterogeneity in CRC associations in Americans of African versus European descent.

Cyclooxygenase-2 gene and lung carcinoma risk

In this study, we aimed to investigate a possible association of the COX-2 polymorphisms with the risk of developing lung carcinoma. COX-2 (-765G→C; -1195A→G) gene polymorphisms were performed by polymerase chain reaction (PCR) and restriction fragment length polymorphism in 118 healthy individuals and 231 patients with lung carcinoma. The present study was the first that addressed the role of the COX-2-765G→C and -1195A→G polymorphisms in lung carcinoma in Turkish population. In the present study, we found that the frequencies of GG, CC, and CG genotypes of COX-2-765G→C and AA, GG, and AG genotypes of -1195A→G in our control group were 0.22, 0.22, 0.55 and 0.59, 0.0, 0.40, respectively. These frequencies in patient group were 0.34, 0.07, 0.58 and 0.74, 0.04, 0.24, respectively. There were statistically significant differences in COX-2-765G→C (P=0.0002) and -1195A→G genotypes (P=0.007) between the controls and patients. We found that individuals carrying -765 GG genotype and -765 G allele of COX-2 or 1195 AA genotype of COX-2 and -765G: -1195A haplotype had an increased risk for the development of lung carcinoma. In contrast, individuals with -765 CC, -1195 AG genotypes and -1195 G allele of COX-2 seem to be protective from lung carcinoma. We suggest that the COX-2-765G→C and -1195A→G genotypes may be a risk factor for lung carcinoma.

Polymorphic human prostaglandin H synthase-2 proteins and their interactions with cyclooxygenase substrates and inhibitors

The cyclooxygenase (COX) activity of prostaglandin H synthase-2 (PGHS-2) is implicated in colorectal cancer and is targeted by nonsteroidal anti-inflammatory drugs (NSAIDs) and dietary n-3 fatty acids. We used purified, recombinant proteins to evaluate the functional impacts of the R228H, E488G, V511A and G587R PGHS-2 polymorphisms on COX activity, fatty acid selectivity and NSAID actions. Compared to wild-type PGHS-2, COX activity with arachidonate was ∼20% lower in 488G and ∼20% higher in 511A. All variants showed time-dependent inhibition by the COX-2-specific inhibitor (coxib) nimesulide, but 488G and 511A had 30-60% higher residual COX activity; 511A also showed up to 70% higher residual activity with other time-dependent inhibitors. In addition, 488G and 511A differed significantly from wild type in Vmax values with the two fatty acids: 488G showed ∼20% less and 511A showed ∼20% more discrimination against eicosapentaenoic acid. The Vmax value for eicosapentaenoate was not affected in 228H or 587R, nor were the Km values or the COX activation efficiency (with arachidonate) significantly altered in any variant. Thus, the E488G and V511A PGHS-2 polymorphisms may predict who will most likely benefit from interventions with some NSAIDs or n-3 fatty acids.

Primary prevention of colorectal cancer

Colorectal cancer has been strongly associated with a Western lifestyle. In the past several decades, much has been learned about the dietary, lifestyle, and medication risk factors for this malignancy. Although there is controversy about the role of specific nutritional factors, consideration of dietary pattern as a whole appears useful for formulating recommendations. For example, several studies have shown that high intake of red and processed meats, highly refined grains and starches, and sugars is related to increased risk of colorectal cancer. Replacing these factors with poultry, fish, and plant sources as the primary source of protein; unsaturated fats as the primary source of fat; and unrefined grains, legumes and fruits as the primary source of carbohydrates is likely to lower risk of colorectal cancer. Although a role for supplements, including vitamin D, folate, and vitamin B6, remains uncertain, calcium supplementation is likely to be at least modestly beneficial. With respect to lifestyle, compelling evidence indicates that avoidance of smoking and heavy alcohol use, prevention of weight gain, and maintenance of a reasonable level of physical activity are associated with markedly lower risks of colorectal cancer. Medications such as aspirin and nonsteroidal anti-inflammatory drugs and postmenopausal hormones for women are associated with substantial reductions in colorectal cancer risk, though their utility is affected by associated risks. Taken together, modifications in diet and lifestyle should substantially reduce the risk of colorectal cancer and could complement screening in reducing colorectal cancer incidence.

Polymorphisms in the xenobiotic transporter Multidrug Resistance 1 (MDR1) and interaction with meat intake in relation to risk of colorectal cancer in a Danish prospective case-cohort study

Background

The xenobiotic transporters, Multidrug Resistance 1 (MDR1/ABCB1) and Breast Cancer Resistance Protein (BCRP/ABCG2) may restrict intestinal absorption of various carcinogens, including heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons (PAH). Cyclooxygenase-2 (COX-2) derived prostaglandins promote gastrointestinal carcinogenesis, affecting angiogenesis, apoptosis, and invasiveness.

The aim of this study was to investigate if polymorphisms in these genes were associated with risk of colorectal cancer (CRC), and to investigate possible interactions with lifestyle factors such as smoking, meat consumption, and NSAID use.

Methods

The following polymorphisms were analyzed; a synonymous MDR1 C3435T (rs1045642) in exon26, G-rs3789243-A in intron3, the functional BCRP C421A (rs2231142), the two COX-2 A-1195G (rs689466) and G-765C (rs20417) in the promoter region, and the COX-2 T8473C (rs5275) polymorphisms in the 3'-untranslated region. The polymorphisms were assessed together with lifestyle factors in a nested case-cohort study of 359 cases and a random cohort sample of 765 participants from the Danish prospective Diet, Cancer and Health study.

Results

Carriers of the variant allele of MDR1 intron 3 polymorphism were at 1.52-fold higher risk of CRC than homozygous wild type allele carriers (Incidence rate ratio (IRR) = 1.52, 95% Confidence Interval (CI): 1.12-2.06). Carriers of the variant allele of MDR1 C3435T exon 26 had a lower risk of CRC than homozygous C-allele carriers (IRR = 0.71 (CI:0.50-1.00)). There was interaction between these MDR1 polymorphisms and intake of red and processed meat in relation to CRC risk. Homozygous MDR1 C3435T C-allele carriers were at 8% increased risk pr 25 gram meat per day (CI: 1.00-1.16) whereas variant allele carriers were not at increased risk (p for interaction = 0.02). COX-2 and BCRP polymorphisms were not associated with CRC risk. There was interaction between NSAID use and MDR1 C3435T and COX-2 T8473C (p-values for interaction 0.001 and 0.04, respectively).

Conclusion

Two polymorphisms in MDR1 were associated with CRC risk and there was interaction between these polymorphisms and meat intake in relation to CRC risk. Our results suggest that MDR1 polymorphisms affect the relationship between meat and CRC risk.

Cyclooxygenase-2 polymorphisms, aspirin treatment, and risk for colorectal adenoma recurrence--data from a randomized clinical trial

Cyclooxygenase-2 (COX-2) catalyzes the rate-limiting step in the production of prostaglandins, potent mediators of inflammation. Chronic inflammation plays an important role in the development and progression of colorectal cancer. Aspirin inhibits COX-2 activity and lowers the risk for colorectal adenomas and cancer. We investigated whether common genetic variation in COX-2 influenced risk for colorectal adenoma recurrence among 979 participants in the Aspirin/Folate Polyp Prevention Study who were randomly assigned to placebo or aspirin and followed for 3 years for the occurrence of new adenomas. Of these participants, 44.2% developed at least one new adenoma during follow-up. Adjusted relative risks and 95% confidence intervals (95% CI) were calculated to test the association between genetic variation at six COX-2 single-nucleotide polymorphisms and adenoma occurrence and interaction with aspirin treatment. Two single-nucleotide polymorphisms were significantly associated with increased adenoma recurrence: for rs5277, homozygous carriers of the minor C allele had a 51% increased risk compared with GG homozygotes (relative risk, 1.51; 95% CI, 1.01-2.25), and for rs4648310, heterozygous carriers of the minor G allele had a 37% increased risk compared with AA homozygotes (relative risk, 1.37; 95% CI, 1.05-1.79). (There were no minor allele homozygotes.) In stratified analyses, there was suggestive evidence that rs4648319 modified the effect of aspirin. These results support the hypothesis that COX-2 plays a role in the etiology of colon cancer and may be a target for aspirin chemoprevention and warrant further investigation in other colorectal adenoma and cancer populations.

COX-2 polymorphisms -765G→C and -1195A→G and colorectal cancer risk

AIM: To determine the possible modulating effect of the COX-2 polymorphisms, -765G→C and -1195A→G, on the risk of colorectal cancer (CRC) in a Dutch population.

METHODS: This case-control study includes 326 patients with CRC and 369 age- and gender-matched controls. Genotypes of the COX-2 polymorphisms -765G→C and -1195A→G were determined by polymerase chain reaction-based restriction fragment length polymorphism. COX-2 genotypes and haplotypes were analyzed and odds ratios with 95% confidence intervals were estimated by logistic regression.

RESULTS: The -765GG genotype was associated with an increased risk of developing CRC (OR, 1.45; 95% CI, 1.03-2.04). No significant difference was observed in the genotype distribution of the -1195A→G polymorphism between patients and controls. The GG/AC haplotype was present significantly less often in patients than in controls (OR 0.44; 95% CI, 0.22-0.85). When the AC, AG and GG haplotypes were investigated separately, the AC haplotype showed a tendency to be less frequent in patients than in controls (OR_(AG/AC) 0.78; 95% CI, 0.57-1.06).

CONCLUSION: The -765GG genotype is associated with an increased risk of developing CRC and the GG/AC haplotype seems to protect against CRC. These findings suggest a modulating role for the COX-2 polymorphisms -765G→C and -1195A→G in the development of CRC in a Dutch population.

Cyclooxygenase-2, multidrug resistance 1, and breast cancer resistance protein gene polymorphisms and inflammatory bowel disease in the Danish population

OBJECTIVE

Crohn's disease (CD) and ulcerative colitis (UC) are characterized by an impaired mucosal defence to normal constituents of the intestinal flora and a dysregulated inflammatory response. The purpose of the study was to investigate whether single nucleotide polymorphisms (SNPs) in genes involved in these processes were associated with CD and UC.

MATERIAL AND METHODS

Allele frequencies of the cyclooxygenase 2 (COX-2/PTGS2/PGHS2) G-765C and breast cancer resistance protein (BCRP/ABCG2) C421A as well as allele and haplotype frequencies of multidrug resistance 1 (MDR1, ABCB1) SNPs G2677T/A, C3435T and G-rs3789243-A (intron 3) were assessed in a Danish case-control study comprising 373 CD and 541 UC patients and 796 healthy controls.

RESULTS

Carriers of the homozygous COX-2 and MDR1 intron 3 variant had a relatively high risk of CD, odds ratio (95% CI) (OR (95% CI))=2.86 ((1.34-5.88) p=0.006) and 1.39 ((0.99-1.92) p=0.054), respectively, and for UC of 2.63 ((1.33-5.26) p=0.005) and 1.28 ((0.96-1.51) p=0.093), respectively, assuming complete dominance. No association was found for BCRP or other MDR1 SNPs, or for selected MDR1 haplotypes. No effect-modification of smoking habit at the time of diagnosis was found.

CONCLUSIONS

An effect of the COX-2 polymorphism on both CD and UC was shown which is compatible with the presence of a recessive allele in linkage equilibrium with the SNP marker in the COX-2 gene. The polymorphism located in intron 3 of the MDR1 gene showed a weak association with CD, and a marginally suggestive association with UC.

Cyclooxygenase polymorphisms in gastric and colorectal carcinogenesis: are conclusive results available?

OBJECTIVE

Cyclooxygenases (COX) are important enzymes not only in the maintenance of mucosal integrity but also in pathological processes, namely in inflammation and tumor development in the gastrointestinal tract. Our goal was to understand whether there is a clear role for COX polymorphisms in gastric and colorectal carcinogenesis.

METHODS

A systematic review was conducted on observational studies assessing the involvement of COX polymorphisms at the onset of gastric or colorectal lesions, retrieved through a MEDLINE database search by May 2008. The dominant genetic model was assumed for each polymorphism and a random-effect model was used for pooling results.

RESULTS

Twenty-two studies were retrieved reporting a total of 26 COX polymorphisms (nine in COX1 and 17 in COX2 genes). Carriers of -1329A, -899C alleles, and *429TT genotype revealed increased risk for gastric cancer [odds ratio (OR)=1.83; 95% confidence interval (CI): 1.07-3.10, OR=2.02; 95% CI: 1.00-4.10 and OR=1.34; 95% CI: 1.06-1.71, respectively). For colorectal lesions, the -899G>C and -1329G>A polymorphisms also showed an increased risk for cancer (OR=1.35; 95% CI: 1.01-1.81 and OR=1.36; 95% CI: 1.11-1.66, respectively). Furthermore, C allele carriers of V102V single nucleotide polymorphisms presented a decreased risk for colorectal adenoma onset (OR=0.77; 95% CI: 0.58-1.03).

CONCLUSION

Although further studies, namely cohorts and/or adequately matched case-control studies, are required to unravel the impact of most COX polymorphisms, clearly there are evidences that support the involvement of -899G>C and -1329G>A COX2 polymorphisms in either gastric or colorectal carcinogenesis. These markers could be used to optimize management strategies (follow-up and/or chemoprevention).

Genetic polymorphisms of cyclooxygenase-2 and colorectal adenoma risk: the Self Defense Forces Health Study

Cyclooxygenase (COX) is a key enzyme in the formation of prostaglandins, and an inducible isoform of COX, COX-2, has been implicated in colorectal carcinogenesis. This study investigated the relation of COX-2 polymorphisms (-1195G>A, -765G>C and 8160A>G) to colorectal adenomas in a case-control study of male officials in the Self Defense Forces (SDF). The study subjects were 455 cases of colorectal adenoma and 1052 controls with no polyps who underwent total colonoscopy. Genotypes were determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method with genomic DNA extracted from the buffy coat. Statistical adjustment was made for age, hospital, rank in the SDF, body mass index (BMI), cigarette smoking, and alcohol intake. A statistically non-significant decrease in the risk of colorectal adenomas was observed for the AA versus GG genotype of -1195G>A polymorphism and for the GC versus GG genotype of -765G>C polymorphism. None had the -765CC genotype in either the case or control groups. No effect modification of overweight, smoking or alcohol use was observed for either -1195G>A or -765G>C polymorphism. The variant allele of the 8160A>G polymorphism was extremely rare. A haplotype of -1195G, -765G and 8160A alleles was associated with a modest increase in the risk (adjusted odds ratio [OR] 1.38, 95% confidence interval [CI] 0.99-1.91), and the increase was more evident for distal adenomas (adjusted OR 1.57, 95% CI 1.04-2.38). Another haplotype of -1195A, -765C and 8160A alleles showed an adjusted OR of 0.22 (95% CI 0.06-0.88). These findings add to evidence for the role of COX-2 in colorectal carcinogenesis and warrant further studies focusing on haplotypes.

A review of gene-drug interactions for nonsteroidal anti-inflammatory drug use in preventing colorectal neoplasia

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to be effective chemopreventive agents for colorectal neoplasia. Polymorphisms in NSAID targets or metabolizing enzymes may affect NSAID efficacy or toxicity. We conducted a literature review to summarize current evidence of gene-drug interactions between NSAID use and polymorphisms in COX1, COX2, ODC, UGT1A6 and CYP2C9 on risk of colorectal neoplasia by searching OVID and PubMed. Of 134 relevant search results, thirteen investigated an interaction. One study reported a significant interaction between NSAID use and the COX1 Pro17Leu polymorphism (P=0.03) whereby the risk reduction associated with NSAID use among homozygous wild-type genotypes was not observed among NSAID users with variant alleles. Recent pharmacodynamic data support the potential for gene-drug interactions for COX1 Pro17Leu. Statistically significant interactions have also been reported for ODC (315G>A), UGT1A6 (Thr181Ala+Arg184Ser or Arg184Ser alone), and CYP2C9 (*2/*3). No statistically significant interactions have been reported for polymorphisms in COX2; however, an interaction with COX2 -765G>C approached significance (P=0.07) in one study. Among seven remaining studies, reported interactions were not statistically significant for COX1, COX2 and ODC gene polymorphisms. Most studies were of limited sample size. Definitions of NSAID use differed substantially between studies. The literature on NSAID-gene interactions to date is limited. Reliable detection of gene-NSAID interactions will require greater sample sizes, consistent definitions of NSAID use and evaluation of clinical trial subjects of chemoprevention studies.

Dietary fat-gene interactions in cancer

Epidemiologic studies have suggested for decades an association between dietary fat and cancer risk. A large body of work performed in tissue culture and xenograft models of cancer supports an important role of various types of fat in modulating the cancer phenotype. Yet, the molecular mechanisms underlining the effects of fat on cancer initiation and progression are largely unknown. The relationships between saturated fat, polyunsaturated fat, cholesterol or phytanic acid with cancer have been reviewed respectively. However, few have considered the relationship between all of these fats and cancer. The purpose of this review is to present a more cohesive view of dietary fat-gene interactions, and outline a working hypothesis of the intricate connection between fat, genes and cancer.

Effect of aspirin on long-term risk of colorectal cancer: consistent evidence from randomised and observational studies

BACKGROUND

Randomised trials have shown that aspirin reduces the short-term risk of recurrent colorectal adenomas in patients with a history of adenomas or cancer, but large trials have shown no effect in primary prevention of colorectal cancer during 10 years' follow-up. However, the delay from the early development of adenoma to presentation with cancer is at least 10 years. We aimed to assess the longer-term effect of aspirin on the incidence of cancers.

METHODS

We studied the effect of aspirin in two large randomised trials with reliable post-trial follow-up for more than 20 years: the British Doctors Aspirin Trial (N=5139, two-thirds allocated 500 mg aspirin for 5 years, a third to open control) and UK-TIA Aspirin Trial (N=2449, two-thirds allocated 300 mg or 1200 mg aspirin for 1-7 years, a third placebo control). We also did a systematic review of all relevant observational studies to establish whether associations were consistent with the results of the randomised trials and, if so, what could be concluded about the likely effects of dose and regularity of aspirin use, other non-steroidal anti-inflammatory drugs (NSAID), and the effect of patient characteristics.

RESULTS

In the randomised trials, allocation to aspirin reduced the incidence of colorectal cancer (pooled HR 0.74, 95% CI 0.56-0.97, p=0.02 overall; 0.63, 0.47-0.85, p=0.002 if allocated aspirin for 5 years or more). However, this effect was only seen after a latency of 10 years (years 0-9: 0.92, 0.56-1.49, p=0.73; years 10-19: 0.60, 0.42-0.87, p=0.007), was dependent on duration of scheduled trial treatment and compliance, and was greatest 10-14 years after randomisation in patients who had had scheduled trial treatment of 5 years or more (0.37, 0.20-0.70, p=0.002; 0.26, 0.12-0.56, p=0.0002, if compliant). No significant effect on incidence of non-colorectal cancers was recorded (1.01, 0.88-1.16, p=0.87). In 19 case-control studies (20 815 cases) and 11 cohort studies (1 136 110 individuals), regular use of aspirin or NSAID was consistently associated with a reduced risk of colorectal cancer, especially after use for 10 years or more, with no difference between aspirin and other NSAIDs, or in relation to age, sex, race, or family history, site or aggressiveness of cancer, or any reduction in apparent effect with use for 20 years or more. However, a consistent association was only seen with use of 300 mg or more of aspirin a day, with diminished and inconsistent results for lower or less frequent doses.

INTERPRETATION

Use of 300 mg or more of aspirin a day for about 5 years is effective in primary prevention of colorectal cancer in randomised controlled trials, with a latency of about 10 years, which is consistent with findings from observational studies. Long-term follow-up is required from other randomised trials to establish the effects of lower or less frequent doses of aspirin.