A polymorphism in the 3' untranslated region of the gene encoding prostaglandin endoperoxide synthase 2 is not associated with an increase in breast cancer risk: a nested case-control study

Interactions between exposure to polycyclic aromatic hydrocarbons and xenobiotic metabolism genes, and risk of breast cancer

PURPOSE

Polycyclic aromatic hydrocarbons (PAHs) are a group of environmental pollutants associated with multiple cancers, including female breast cancer. Several xenobiotic metabolism genes (XMGs), including the CYP450 family, play an important role in activating and detoxifying PAHs, and variations in the activity of the enzymes they encode can impact this process. This study aims to examine the association between XMGs and breast cancer, and to assess whether these variants modify the effects of PAH exposure on breast cancer risk.

METHODS

In a case-control study in Vancouver, British Columbia, and Kingston, Ontario, 1037 breast cancer cases and 1046 controls had DNA extracted from blood or saliva and genotyped for 138 single nucleotide polymorphisms (SNPs) and tagSNPs in 27 candidate XMGs. Occupational PAH exposure was assessed using a measurement-based job-exposure matrix.

RESULTS

An association between genetic variants and breast cancer was observed among six XMGs, including increased risk among the minor allele carriers of AKR1C3 variant rs12387 (OR 2.71, 95% CI 1.42-5.19) and AKR1C4 variant rs381267 (OR 2.50, 95% CI 1.23-5.07). Heterogeneous effects of occupational PAH exposure were observed among carriers of AKR1C3/4 variants, as well as the PTGS2 variant rs5275.

CONCLUSION

Our findings support an association between SNPs of XMGs and female breast cancer, including novel genetic variants that modify the toxicity of PAH exposure. These results highlight the interplay between genetic and environmental factors, which can be helpful in understanding the modifiable risks of breast cancer and its complex etiology.

Genetic Variants in COX2 and ALOX Genes and Breast Cancer Risk in White and Black Women

COX and ALOX genes are involved in inflammatory processes and that may be related to breast cancer risk differentially between White and Black women. We evaluated distributions of genetic variants involved in COX2 and ALOX-related pathways and examined their associations with breast cancer risk among 1,275 White and 1,299 Black cases and controls who participated in the Women’s Circle of Health Study. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable-adjusted logistic regression models. Our results showed differential associations of certain genetic variants with breast cancer according to menopausal and ER status in either White or Black women. In White women, an increased risk of breast cancer was observed for COX2-rs689470 (OR: 2.02, P = 0.01) in the dominant model, and was strongest among postmenopausal women (OR: 2.72, P = 0.02) and for estrogen receptor positive (ER+) breast cancers (OR: 2.60, P = 0.001). A reduced risk was observed for ALOX5-rs7099874 (OR: 0.75, P = 0.01) in the dominant model, and was stronger among postmenopausal women (OR: 0.68, P = 0.03) and for ER+ cancer (OR: 0.66, P = 0.001). Four SNPs (rs3840880, rs1126667, rs434473, rs1042357) in the ALOX12 gene were found in high LD (r² >0.98) in White women and were similarly associated with reduced risk of breast cancer, with a stronger association among postmenopausal women and for ER− cancer. Among Black women, increased risk was observed for ALOX5-rs1369214 (OR: 1.44, P = 0.003) in the recessive model and was stronger among premenopausal women (OR: 1.57, P = 0.03) and for ER+ cancer (OR: 1.53, P = 0.003). Our study suggests that genetic variants of COX2 and ALOX genes are associated with breast cancer, and that these associations and genotype distributions differ in subgroups defined by menopausal and ER status between White and Black women. Findings may provide insights into the etiology of breast cancer and areas for further research into reasons for breast cancer differences between races.

Prostaglandin Endoperoxide H Synthase-2 (PGHS-2) Variants and Risk of Obesity and Microvascular Dysfunction Among Tunisians: Relevance of rs5277 (306G/C) and rs5275 (8473T/C) Genetic Markers

The purpose of this study was to determine the impact of six PGHS-2 genetic variants on obesity development and microvascular dysfunction. The study included 305 Tunisian subjects (186 normal weights, 35 overweights and 84 obeses). PCR analyses were used for allelic discrimination between polymorphisms. Prostaglandin (PGE2, PGI2), leptin, and matrix metalloproteinase (MMP1, 2, 3, 9) levels were evaluated by ELISA. Fatty acid composition was performed by gas chromatography-mass spectrometry. Our results revealed that subjects carrying the PGHS-2 306CC (rs5277) and 8473CC (rs5275) genotypes present higher anthropometric values compared to wild-type genotypes (306GG, BMI (Kg/m²): 27.11 ± 0.58; WC (cm): 93.09 ± 1.58; 306CC, BMI: 33.83 ± 2.46; WC: 109.93 ± 5.41; 8473TT, BMI: 27.75 ± 0.68; WC: 93.96 ± 1.75; 8473CC, BMI: 33.72 ± 2.2; WC: 117.89 ± 2.94). A reduced microvascular reactivity and a higher PGE2 level were also found in individuals with the 306CC and 8473CC genotypes in comparison to 306GG and 8473TT carriers (306GG, Peak Ach-CVC (PU/mmHg): 0.46 ± 0.03; PGE2 (pg/ml): 7933.1 ± 702; 306CC, Peak Ach-CVC: 0.24 ± 0.01; PGE2: 13,380.3 ± 966.2; 8473TT, Peak Ach-CVC: 0.48 ± 0.05; PGE2: 7086.41 ± 700.31; 8473CC, Peak Ach-CVC: 0.23 ± 0.01; PGE2: 13,175.7 ± 1165.8). Fatty acid analysis showed a significant increase of palmitic acid (PA) (34.2 ± 2.09 vs. 16.82% ± 1.76, P < 0.001), stearic acid (SA) (25.76 ± 3.29 vs. 9.05% ± 2.53, P < 0.001), and linoleic acid (LA) (5.25 ± 1.18 vs. 0.5% ± 0.09, P < 0.001) levels in individuals carrying the PGHS-2 306CC genotype when compared to GG genotype individuals. Subjects with the 8473CC genotype showed also a significant increase of PA, SA ,and LA levels when compared to TT genotype carriers (PA: 38.02 ± 1.51 vs. 12.65% ± 1.54, P < 0.001; SA: 32.96 ± 1.87 vs. 1.38% ± 0.56, P < 0.001; LA: 26.84 ± 2.09 vs. 3.7% ± 1.54, P < 0.001). Logistic regression analysis revealed that PGHS-2 306CC and 8473CC variants are significantly associated with obesity status (OR 6.25, CI (1.8-21.6), P = 0.004; OR 3.01, CI (1.13-8.52), P = 0.03, respectively). Haplotypes containing the C₃₀₆:T₈₄₇₃ (OR 2.91; P = 0.01) and G_306:C₈₄₇₃ (OR 5.25; P = 0.002) combinations were associated with an enhanced risk for obesity development in the studied population. In conclusion, our results highlight that PGHS-2 306G/C and 8473T/C variants could be useful indicators of obesity development, inflammation, and microvascular dysfunction among Tunisians.

Association between cyclooxygenase-2 (COX-2) 8473 T > C polymorphism and cancer risk: a meta-analysis and trial sequential analysis

Background

Numerous studies have investigated the relationship between COX-2 8473 T > C polymorphism and cancer susceptibility, however, the results remain controversial. Therefore, we carried out the present meta-analysis to obtain a more accurate assessment of this potential association.

Methods

In this meta-analysis, 79 case-control studies were included with a total of 38,634 cases and 55,206 controls. We searched all relevant articles published in PubMed, EMBASE, OVID, Web of Science, CNKI and Wanfang Data, till September 29, 2017. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the strength of the association. We performed subgroup analysis according to ethnicity, source of controls, genotyping method and cancer type. Moreover, Trial sequential analysis (TSA) was implemented to decrease the risk of type I error and estimate whether the current evidence of the results was sufficient and conclusive.

Results

Overall, our results indicated that 8473 T > C polymorphism was not associated with cancer susceptibility. However, stratified analysis showed that the polymorphism was associated with a statistically significant decreased risk for nasopharyngeal cancer and bladder cancer, but an increased risk for esophageal cancer and skin cancer. Interestingly, TSA demonstrated that the evidence of the result was sufficient in this study.

Conclusion

No significant association between COX-2 8473 T > C polymorphism and cancer risk was detected.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4753-3) contains supplementary material, which is available to authorized users.

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.

Cyclooxygenase-2 (COX-2) gene polymorphism in patients with differentiated thyroid carcinomas in the Turkish population

Background/aim: The most common thyroid malignancies are papillary and follicular thyroid carcinomas. They account for approximately 85%-90% of all thyroid cancers. Recent studies have reported the relevance of cyclooxygenase-2 (COX-2) gene polymorphism in human carcinogenesis. The aim of this study was to investigate the relationship between thyroid carcinoma and COX-2 gene polymorphism in the Turkish population.Materials and methods: We included a total of 96 differentiated thyroid cancer patients (mean age: 46.9 ± 10.3 years; 14 males, 82 females) and 83 healthy control subjects (mean age: 46.0 ± 10.6 years; 39 males, 44 females). The frequency of -765G>C, -8473T>C, and 1195A>G gene polymorphisms in the COX-2 promoter region was investigated in thyroid cancer patients and the control group using the high-resolution melting method. Results: COX-2-765G>C and COX-2-1195A>G gene polymorphisms were similar between thyroid cancer patients and the control group. There was a statistically significant difference between COX-2-8473T>C gene polymorphism in the thyroid cancer group and the control group (P = 0.012).Conclusion: The single nucleotide gene polymorphism COX-2-8473T>C might contribute to genetic susceptibility to differentiated thyroid cancer in the Turkish population.

Variability of the drug response to nonsteroidal anti-inflammatory drugs according to cyclooxygenase-2 genetic polymorphism

Purpose

Cyclooxygenase (COX) is the main pharmacodynamic target of nonsteroidal anti-inflammatory drugs (NSAIDs). We investigated the inhibitory effects on COX-2 after NSAIDs administration using a lipopolysaccharide (LPS)-derived COX-2 induction model in whole blood, according to the genotypes of COX-2 single-nucleotide polymorphisms (SNPs).

Patients and methods

Seven genotypes of COX-2 SNPs were selected from public databases and analyzed in 324 healthy subjects. Two genotypes showing a high percentage of variability were selected. A clinical trial examining pharmacodynamics according to the genotype of two SNPs (rs5275 and rs689466) was conducted. Twenty subjects were administered a single oral dose of 200 mg of celecoxib, and pharmacokinetic and pharmacodynamic analyses were performed.

Results

In the analysis of the pharmacokinetic parameters, significant differences in drug exposure were not investigated for each SNP genotype. The pharmacodynamic analysis revealed that the maximum effect of COX-2 inhibition was achieved at 2.0 hours for all genotypes of COX-2 SNPs after a single oral administration of 200 mg celecoxib. The inhibitory effects according to the genotype of COX-2 SNPs were investigated, and the area under the effect curve of the rs689466 GG genotype was significantly lower than that for the AA or AG genotype.

Conclusion

Our results demonstrated that inhibitory effects of celecoxib on COX-2 induction were different according to the genotype of COX-2 SNPs. In the present study, rs689466 is responsible for the variability of the response to celecoxib, suggesting that a subject with the GG genotype of rs689466 would be more responsive to celecoxib in terms of COX-2 inhibition.

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.

mRNA profiling reveals determinants of trastuzumab efficiency in HER2-positive breast cancer

Intrinsic and acquired resistance to the monoclonal antibody drug trastuzumab is a major problem in the treatment of HER2-positive breast cancer. A deeper understanding of the underlying mechanisms could help to develop new agents. Our intention was to detect genes and single nucleotide polymorphisms (SNPs) affecting trastuzumab efficiency in cell culture. Three HER2-positive breast cancer cell lines with different resistance phenotypes were analyzed. We chose BT474 as model of trastuzumab sensitivity, HCC1954 as model of intrinsic resistance, and BTR50, derived from BT474, as model of acquired resistance. Based on RNA-Seq data, we performed differential expression analyses on these cell lines with and without trastuzumab treatment. Differentially expressed genes between the resistant cell lines and BT474 are expected to contribute to resistance. Differentially expressed genes between untreated and trastuzumab treated BT474 are expected to contribute to drug efficacy. To exclude false positives from the candidate gene set, we removed genes that were also differentially expressed between untreated and trastuzumab treated BTR50. We further searched for SNPs in the untreated cell lines which could contribute to trastuzumab resistance. The analysis resulted in 54 differentially expressed candidate genes that might be connected to trastuzumab efficiency. 90% of 40 selected candidates were validated by RT-qPCR. ALPP, CALCOCO1, CAV1, CYP1A2 and IGFBP3 were significantly higher expressed in the trastuzumab treated than in the untreated BT474 cell line. GDF15, IL8, LCN2, PTGS2 and 20 other genes were significantly higher expressed in HCC1954 than in BT474, while NCAM2, COLEC12, AFF3, TFF3, NRCAM, GREB1 and TFF1 were significantly lower expressed. Additionally, we inferred SNPs in HCC1954 for CAV1, PTGS2, IL8 and IGFBP3. The latter also had a variation in BTR50. 20% of the validated subset have already been mentioned in literature. For half of them we called and analyzed SNPs. These results contribute to a better understanding of trastuzumab action and resistance mechanisms.

Lack of association between COX-2 8473T>C polymorphism and breast cancer risk: a meta-analysis

Aim of the study

Results of recent published studies on the association between the COX-2 8473T>C polymorphism and the risk of breast cancer have often been conflicting. To make a more precise estimation of the potential relationship, a meta-analysis was performed.

Material and methods

A total of seven case-control studies with 7,033 cases and 9,350 controls were included in the current meta-analysis through searching the databases of PubMed, Embase, and Cochrane Library (up to March 1^st, 2013). The odds ratio (OR) and 95% confidence interval (95% CI) were calculated to assess the strength of the association. The meta-analysis was conducted in a fixed/random effect model.

Results

We found no significant associations for all genetic models after all studies were pooled into the meta-analysis (for C vs. T: OR = 0.974, 95% CI: 0.906–1.047, p = 0.471; for CC vs. TT: OR = 0.957, 95% CI: 0.803–1.140, p = 0.62; for TC vs. TT: OR = 0.964, 95% CI: 0.881–1.055, p = 0.421; for CC + TC vs. TT: OR = 0.963, 95% CI: 0.880–1.053, p = 0.406; for CC vs. TT + TC: OR = 0.978, 95% CI: 0.831–1.15, p = 0.788). We also observed no obvious associations in the subgroup analyses by ethnicity (Caucasian) and source of controls (population based, PB) for all genetic models.

Conclusions

Current evidence suggests that the COX-2 8473T>C polymorphism is not associated with breast cancer risk.

Five COX-2 gene polymorphisms and risk of breast cancer: an updated meta-analysis based on 19 case-control studies

The correlationship between COX-2 gene polymorphisms and breast cancer has been wildly studied, but the results remain controversial. Hence, the present meta-analysis aimed to investigate the association between COX-2 SNPs (rs5275, rs20417, rs689466, rs5277, rs2206593) and risk of breast cancer. Data were collected from PubMed, Embase and China National Knowledge Infrastructure. Summary odds ratio (OR) with 95 % confidence interval (CI) was applied to assess the relationship. Heterogeneity test, sensitivity analysis and publication bias test were also performed. There were 17 articles that contained 19 studies in this research. Fourteen case-control studies with 15,007 breast cancer cases and 20,005 controls were concerning rs5275 polymorphism, and 8 case-control studies with 10,216 cases and 12,839 controls were about rs20417 polymorphism. Other three polymorphisms (rs689466, rs2206593, rs5277) were studied in 5, 3 and 3 studies, respectively. COX-2-rs20417 CC genotype was significantly associated with increased risk of breast cancer when comparing to G allele [ORs were 1.231 (1.050-1.444) for CC vs. GG, P = 0.01, 1.223 (1.045-1.432) for CC vs. G carrier, P = 0.01]. Furthermore, the results of the subgroup analysis by ethnicity suggested that C allele significantly contributed to the risk of breast cancer for Asians [1.459 (1.182-1.802) for GC vs. GG, 1.472 (1.201-1.805) for C carrier vs. GG]. However, no association was found for rs5275, rs689466, rs5277 and rs2206593 in all comparison modes. This meta-analysis indicated that the COX-2 rs20417 polymorphism contributed to genetic susceptibility of breast cancer. In contrast, COX-2 rs5275, rs689466, rs2206593 and rs5277 polymorphisms might be not associated with the risk of breast cancer.

Associations between ALOX, COX, and CRP polymorphisms and breast cancer among Hispanic and non-Hispanic white women: The breast cancer health disparities study

Chronic inflammation is suggested to be associated with specific cancer sites, including breast cancer. Recent research has focused on the roles of genes involved in the leukotriene/lipoxygenase and prostaglandin/cyclooxygenase pathways in breast cancer etiology. We hypothesized that genes in ALOX/COX pathways and CRP polymorphisms would be associated with breast cancer risk and mortality in our sample of Hispanic/Native American (NA) (1430 cases, 1599 controls) and non-Hispanic white (NHW) (2093 cases, 2610 controls) women. A total of 104 Ancestral Informative Markers was used to distinguish European and NA ancestry. The adaptive rank truncated product (ARTP) method was used to determine the significance of associations for each gene and the inflammation pathway with breast cancer risk and by NA ancestry. Overall, the pathway was associated with breast cancer risk (PARTP = 0.01). Two-way interactions with NA ancestry (P(adj)  < 0.05) were observed for ALOX12 (rs2292350, rs2271316) and PTGS1 (rs10306194). We observed increases in breast cancer risk in stratified analyses by tertiles of polyunsaturated fat intake for ALOX12 polymorphisms; the largest increase in risk was among women in the highest tertile with ALOX12 rs9904779CC (Odds Ratio (OR), 1.49; 95% Confidence Interval (CI) 1.14-1.94, P(adj) = 0.01). In a sub-analysis stratified by NSAIDs use, two-way interactions with NSAIDs use were found for ALOX12 rs9904779 (P(adj)  = 0.02), rs434473 (P(adj ) = 0.02), and rs1126667 (P(adj)  =  0.01); ORs for ALOX12 polymorphisms ranged from 1.55 to 1.64 among regular users. Associations were not observed with breast cancer mortality. These findings could support advances in the discovery of new pathways related to inflammation for breast cancer treatment.

Association of the three common SNPs of cyclooxygenase-2 gene (rs20417, rs689466, and rs5275) with the susceptibility of breast cancer: an updated meta-analysis involving 34,590 subjects

Several single nucleotide polymorphisms have been identified in cyclooxygenase-2 (COX-2) genes (e.g., −765 G>C (rs20417), −1195G>A (rs689466), and 8473 C>T (rs5275)). The association of these SNPs with the risk of different cancer types is still controversial. This study aims to evaluate the correlation between these SNPs and breast cancer risk in different ethnic groups. We have searched PubMed, Web of Knowledge, and Embase for relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of the associations. A total of 13 studies (15,330 cases and 19,260 controls) were eligible for meta-analysis. This meta-analysis showed that COX-2 rs20417 polymorphism was correlated with an increased risk of breast cancer in Caucasians, while rs689466 was associated with a decreased risk of breast cancer in Caucasians. The rs5275 polymorphism had no association with breast cancer risk.

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.

Cyclooxygenase-2 169C>G and 8473T>C gene polymorphisms and prostaglandin E2 level in breast cancer: a case-control study

AIMS

Cyclooxygenase 2 (COX-2) with the resulting prostaglandin E2 (PGE2) is linked to increased risk of human breast cancer (BC). The aim of this study was to determine COX-2 169C>G and 8473T>C gene polymorphisms and PGE2 level at various stages of BC clarifying the role of COX-2 gene polymorphism and PGE2 in relation to BC.

METHODS

The study population comprised 160 women at different stages of BC and 150 gender- and age-matched healthy control subjects. Plasma PGE2 was measured by ELISA, the COX-2 gene polymorphisms were determined using PCR-RFLP.

RESULTS

The variant alleles COX-2 169G and 8473C were significantly associated with BC susceptibility [OR=3.1, 95% CI (2.2-4.4), P<0.001 for 169C>G and OR=1.74, 95%CI (1.3-2.4), P=0.005 for 8473C]. However, both COX-2 gene polymorphisms were not associated with breast cancer stage. Plasma PGE2 levels were significantly increased in patients compared to the controls. In early and late stages of BC, there was a significant increase in the plasma PGE2 levels towards the presence of homozygous GG compared with homozygous CC (P<0.001) for 169 C>G, also towards the presence of CC than TT (P<0.001) for 8473T>C SNP.

CONCLUSION

The 169C>G and 8473T>C polymorphisms of the COX-2 gene were associated with the BC in Egyptian women. Furthermore, individuals with COX-2 169GG and 8473CC genotypes showed significant increase in plasma PGE2 levels. PGE2 levels may serve as a predictor of poor prognosis in patients with BC.

An association between the PTGS2 rs5275 polymorphism and colorectal cancer risk in families with inherited non-syndromic predisposition

Recently our group completed a genome-wide linkage study investigating Australian and Spanish families with inherited risk of colorectal cancer (CRC). A minor linkage peak from that study located on chromosome 1 correlates with the location of a known CRC risk-modifying gene, prostaglandin synthase (PTGS2). PTGS2 encodes the inducible prostaglandin synthase enzyme cyclooxygenase-2 (COX-2). Prostaglandins are implicated in the initiation of carcinogenesis and progression of tumours. Sequencing of PTGS2 in a small subset of affected individuals identified a high frequency of the minor C allele of single nucleotide polymorphism rs5275. We then genotyped the rs5275 polymorphism in 183 affected and 223 unaffected individuals from our CRC predisposed families. Tests for association in the presence of linkage were made using family-based association tests. The C allele was found to be significantly associated (P<0.01) with diagnosis of hereditary non-syndromic CRC (P=0.0094, dominant model) and an earlier age of diagnosis (P=0.0089, heterozygous-advantage model). Interestingly, by stratifying the age of diagnosis data, we observed a speculative gender-discordant effect. Relative to other groups, female CC carriers were diagnosed less when young, but by 60 years of age were the most at risk group. Conversely, CT carriers of both genders showed a consistently earlier diagnosis relative to TT carriers. Our results suggest potential differential age-and gender-dependent efficacies of chemopreventative COX-2 inhibitors in the context of non-syndromic colorectal cancer.

Cyclooxygenase-2 ( COX -2) gene-765G/C polymorphism and advanced-stage endometriosis in Korean women

PROBLEM

We investigated the association of COX -2 gene-765G/C polymorphism and risk of advanced-stage endometriosis in Korean women.

METHOD OF STUDY

This study consisted of 268 women with advanced-stage endometriosis and 242 control women without endometriosis in Korea. Subjects were genotyped for the -765G/C polymorphism of the COX -2 gene by RFLP-PCR analysis.

RESULTS

There were significant differences in the genotype distributions of the -765G/C polymorphism between patients with advanced-stage endometriosis and control subjects. The C allele for -765G/C was associated with significantly lower risk of advanced-stage endometriosis (OR, 0.14; 95% CI, 0.06-0.30).

CONCLUSIONS

We have demonstrated a significant genetic association between the -765G/C polymorphism and advanced-stage endometriosis in Korean women. The -765C allele may be protective against the development of the disease in Korean women.

Polymorphisms in cycloxygenase-2 gene and breast cancer prognosis: association between PTGS2 haplotypes and histopathological features

Cyclooxygenase-2 (COX-2) overexpression is associated with worse prognosis in breast cancer. COX-2 is encoded by a polymorphic gene, called PTGS2, and its expression may be genetically influenced. In this article, we investigate the association between PTGS2 haplotypes and histopathological parameters with prognostic value on the clinical outcome of breast cancer. The study involved 606 women under current treatment for non-metastatic breast cancer. Patients were genotyped for rs689465, rs689466, rs20417, and rs5275, and their haplotypes were inferred. The distribution of PTGS2 genotypes and haplotypes was evaluated according to histopathological categorical groups used for prognostic determination of low/intermediate versus high risk of tumor recurrence. Our results indicate positive associations between variant genotypes of rs689465 and estrogen receptor negativity (OR: 1.59, 95% CI: 1.04-2.44, P: 0.02) or HER2 positivity (OR: 1.79, 95% CI: 1.00-3.18, P: 0.03), and between variant genotypes of rs20417 and estrogen receptor negativity (OR: 1.75, 95% CI: 1.15-2.57, P: 0.005), progesterone receptor negativity (OR: 1.56, 95% CI: 1.09-2.22, P: 0.01) or HER2 positivity (OR: 1.80, 95% CI: 1.04-3.13, P: 0.02). In contrast, variant genotypes of rs689466 are negatively associated with estrogen receptor negativity (OR: 0.57, 95% CI: 0.33-0.98, P: 0.03). A total of eight haplotypes were inferred, and there was a significant difference in their distribution as a function of tumor size (P: 0.011), estrogen receptor status (P: 0.018), and HER2 status (P: 0.025). PTGS2 haplotype *7 (formed by rs689465G, rs689466A, rs20417C, and rs5275T) is positively associated with higher tumor size (OR: 3.72, 95% CI: 1.19-11.22, P: 0.006), estrogen receptor negativity (OR: 2.43, 95% CI: 0.97-5.98, P: 0.032), progesterone receptor negativity (OR: 2.58, 95% CI: 1.05-6.39, P: 0.02), and HER2 positivity (OR: 4.17, 95% CI: 1.19-14.44, P: 0.007). Our results suggest that PTGS2 haplotype *7 may contribute to higher growth of untreated breast cancer and that PTGS2 haplotypes need to be considered in the characterization of breast cancer prognosis.

Polymorphisms in regulatory regions of cyclooxygenase-2 gene and breast cancer risk in Brazilians: a case-control study

Background

Cyclooxygenase-2 (COX-2) is up-regulated in several types of cancer, and it is hypothesized that COX-2 expression may be genetically influenced. Here, we evaluate the association between single-nucleotide polymorphisms (SNPs) in the COX-2 gene (PTGS2) and the occurrence of breast cancer among Brazilian women.

Methods

The study was conducted prospectively in two steps: First, we screened the promoter region and three fragments of the 3'-untranslated region of PTGS2 from 67 healthy Brazilians to identify SNPs and to select those with a minor allele frequency (MAF) of at least 0.10. The MAF of these selected SNPs was further characterized in 402 healthy volunteers to evaluate potential differences related to heterogeneous racial admixture and to estimate the existence of linkage disequilibrium among the SNPs. The second step was a case-control study with 318 patients and 273 controls designed to evaluate PTGS2 genotype- or haplotype-associated risk of breast cancer.

Results

The screening analysis indicated nine SNPs with the following MAFs: rs689465 (0.22), rs689466 (0.15), rs20415 (0.007), rs20417 (0.32), rs20419 (0.015), rs5270 (0.02), rs20424 (0.007), rs5275 (0.22) and rs4648298 (0.01). The SNPs rs689465, rs689466, rs20417 and rs5275 were further studied: Their genotypic distributions followed Hardy-Weinberg equilibrium and the MAFs were not affected by gender or skin color. Strong linkage disequilibrium was detected for rs689465, rs20417 and rs5275 in the three possible pairwise combinations. In the case-control study, there was a significant increase of rs5275TC heterozygotes in cases compared to controls (OR = 1.44, 95% CI = 1.01-2.06; P = 0.043), and the haplotype formed by rs689465G, rs689466A, rs20417G and rs5275C was only detected in cases. The apparent association with breast cancer was not confirmed for rs5275CC homozygotes or for the most frequent rs5275C-containing haplotypes.

Conclusions

Our results indicate no strong association between the four most frequent PTGS2 SNPs and the risk of breast cancer.

Polymorphisms in oxidative stress and inflammation pathway genes, low-dose ionizing radiation, and the risk of breast cancer among US radiologic technologists

OBJECTIVE

Ionizing radiation, an established breast cancer risk factor, has been shown to induce oxidative damage and chronic inflammation. Polymorphic variation in oxidative stress and inflammatory-mediated pathway genes may modify radiation-related breast cancer risk.

METHODS

We estimated breast cancer risk for 28 common variants in 16 candidate genes involved in these pathways among 859 breast cancer cases and 1,083 controls nested within the US Radiologic Technologists cohort. We estimated associations between occupational and personal diagnostic radiation exposures with breast cancer by modeling the odds ratio (OR) as a linear function in logistic regression models and assessed heterogeneity of the dose-response across genotypes.

RESULTS

There was suggestive evidence of an interaction between the rs5277 variant in PTGS2 and radiation-related breast cancer risk. The excess OR (EOR)/Gy from occupational radiation exposure = 5.5 (95%CI 1.2-12.5) for the GG genotype versus EOR/Gy < 0 (95%CI < 0-3.8) and EOR/Gy < 0 (95%CI < 0-14.8) for the GC and CC genotypes, respectively, (p (interaction) = 0.04). The association between radiation and breast cancer was not modified by other SNPs examined.

CONCLUSIONS

This study suggests that variation in PTGS2 may modify the breast cancer risk from occupational radiation exposure, but replication in other populations is needed to confirm this result.

Pooled analysis of the association of PTGS2 rs5275 polymorphism and NSAID use with invasive ovarian carcinoma risk

Inflammation is postulated to play an important role in ovarian carcinogenesis. Prostaglandin endoperoxide synthase 2 (PTGS2) is responsible for the conversion of arachidonic acid to prostaglandins in response to inflammation. In a pooled analysis of two population-based studies, the Hawaii Ovarian Cancer Case-Control Study and the New England Case-Control Study, including 1,025 women with invasive ovarian carcinoma and 1,687 cancer-free controls, the association of ovarian cancer risk with the PTGS2 rs5275 polymorphism and the use of nonsteroidal antiinflammatory drugs (NSAIDs) were examined. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression. In the pooled analysis, the CC genotype was associated with a reduced risk of nonserous ovarian carcinoma (OR = 0.66; CI: 0.44-0.98). In addition, the lowest risk was observed among carriers of the CC genotype who were users of only nonaspirin NSAIDs (OR = 0.43; CI:0.20-0.93) in all women combined. The association of PTGS2 rs5275 with nonserous ovarian carcinoma and possible effect modification by NSAID use needs further validation, preferably in prospective studies.

Genetic variants in COX-2, non-steroidal anti-inflammatory drugs, and breast cancer risk: the Western New York Exposures and Breast Cancer (WEB) Study

Chronic inflammation has been consistently associated with cancers of several sites, including the breast, and inhibition of inflammation through the use of non-steroidal anti-inflammatory drugs (NSAIDs) has been inversely associated with risk. As NSAIDs bind with cyclooxygenase-2 (COX-2), genetic variation in COX-2 may influence breast cancer risk by affecting inflammatory response and response to NSAID use. We identified eight single nucleotide polymorphisms (SNPs) for COX-2 and examined their association with risk of breast cancer in a population-based case-control study in Western New York. Cases had incident, first primary, histologically confirmed breast cancer (n = 1077). Controls (n = 1910) were randomly selected from NY Department of Motor Vehicles records (< 65) or Medicare rolls (≥ 65). Participants were queried on adult lifetime use of aspirin and recent use of ibuprofen. Unconditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). One SNP, rs2745559, was associated with an increased risk of breast cancer (OR 1.23, 95% CI 1.03-1.46). Associations with other variants were not evident. Significant interaction (P interaction = 0.04) between recent aspirin use and rs4648261 was also observed. Variation in COX-2 was modestly associated with breast cancer risk, indicating that COX-2 may play a role in breast carcinogenesis. Better understanding of the role of COX-2 genetic variation and interaction with NSAID use in breast carcinogenesis has potential to inform prevention strategies.

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.

The effect of genetic polymorphisms of cyclooxygenase 2 on acute pancreatitis in Turkey

OBJECTIVES

The aims of our study were to determine if polymorphisms in the cyclooxygenase 2 (COX-2) gene is associated with acute pancreatitis (AP) and to evaluate if inflammation risk is associated with specific COX-2 gene haplotypes containing these polymorphisms.

METHODS

The COX-2 genotypes for 7 polymorphisms (rs5275, rs2206593, rs4648262, rs4648261, rs2066826, rs5277, rs2745557) were determined using polymerase chain reaction-restriction fragment length polymorphism analysis in 103 patients with AP and 92 healthy controls.

RESULTS

Except for rs5275, the frequencies of COX-2 polymorphisms were both similar in patients with mild or severe pancreatitis, so were in pancreatitis patients and in controls. Only rs5275 was statistically significantly associated with AP risk. The association was seen with rs5275 (P = 0.03); specifically, patients carrying the TT genotype in comparison with patients carrying the CC genotype had a significantly lower risk of disease (odds ratio, 1.88; 95% confidence interval, 1.06-3.34). Haplotypes with nucleotide T at the -18491961 position (rs5275) and A at the 184915627 position (rs4648261) of COX-2 promoter seem to increase susceptibility (odds ratio, 2.46; 95% confidence interval, 1.15-5.29; P = 0.02).

CONCLUSIONS

These findings suggest that the rs5275 polymorphism in the 3'-untranslated region of the COX-2 gene may be used as 1 marker for defining the risk of AP.

Current evidence on the relationship between polymorphisms in the COX-2 gene and breast cancer risk: a meta-analysis

The association between single-nucleotide polymorphisms (SNPs) in the COX-2 gene and breast cancer risk is still ambiguous. We here try to derive a more precise estimation of the relationship by performing a meta-analysis based on currently available evidence from literature. More than 15 SNPs have been studied, and the most studied genetic variants were rs5275, rs5277, and rs20417. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association between each polymorphism and breast cancer risk under the codominant model, dominant model, and recessive model, respectively (nine studies with 6,968 cases and 9,126 controls for rs5275; three studies with 2,901 cases and 3,463 controls for rs20417; two studies with 5,551 cases and 6,208 controls for rs5277). No overall significant associations were observed in single-locus analysis between the three polymorphisms of COX-2 and breast cancer risk, though a borderline significant increased risk of breast cancer was detected with rs5277 in a recessive model (OR: 1.217, 95% CI: 0.958-1.547, P = 0.107). The results were not changed when studies were stratified by ethnicity. In conclusion, the present meta-analysis suggests that none of the most studied three SNPs (rs5275, rs20417, and rs5277) in the COX-2 gene is a conspicuous low-penetrant risk factor for developing breast cancer. There is a need for further large studies into the role of these polymorphisms (especially rs5277) and other potentially functional polymorphisms/haplotypes in the COX-2 gene as breast cancer risk modifiers.

PTGS2 and IL6 genetic variation and risk of breast and prostate cancer: results from the Breast and Prostate Cancer Cohort Consortium (BPC3)

Genes involved in the inflammation pathway have been associated with cancer risk. Genetic variants in the interleukin-6 (IL6) and prostaglandin-endoperoxide synthase-2 (PTGS2, encoding for the COX-2 enzyme) genes, in particular, have been related to several cancer types, including breast and prostate cancers. We conducted a study within the Breast and Prostate Cancer Cohort Consortium to examine the association between IL6 and PTGS2 polymorphisms and breast and prostate cancer risk. Twenty-seven polymorphisms, selected by pairwise tagging, were genotyped on 6292 breast cancer cases and 8135 matched controls and 8008 prostate cancer cases and 8604 matched controls. The large sample sizes and comprehensive single nucleotide polymorphism tagging in this study gave us excellent power to detect modest effects for common variants. After adjustment for multiple testing, none of the associations examined remained statistically significant at P = 0.01. In analyses not adjusted for multiple testing, one IL6 polymorphism (rs6949149) was marginally associated with breast cancer risk (TT versus GG, odds ratios (OR): 1.32; 99% confidence intervals (CI): 1.00-1.74, P(trend) = 0.003) and two were marginally associated with prostate cancer risk (rs6969502-AA versus rs6969502-GG, OR: 0.87, 99% CI: 0.75-1.02; P(trend) = 0.002 and rs7805828-AA versus rs7805828-GG, OR: 1.11, 99% CI: 0.99-1.26; P(trend) = 0.007). An increase in breast cancer risk was observed for the PTGS2 polymorphism rs7550380 (TT versus GG, OR: 1.38, 99% CI: 1.04-1.83). No association was observed between PTGS2 polymorphisms and prostate cancer risk. In conclusion, common genetic variation in these two genes might play at best a limited role in breast and prostate cancers.

Functional polymorphisms of the cyclooxygenase (PTGS2) gene and risk for gallbladder cancer in a North Indian population

BACKGROUND

Cyclooxygenase-2 (PTGS2) overexpression has been implicated in various cancers. We aimed to evaluate the role of PTGS2 -1195G>A [reference sequence (rs) 689466], -765G>C (rs20417) and +8473T>C (rs5275) polymorphisms in conferring interindividual susceptibility to gallbladder cancer.

MATERIALS AND METHODS

The study included 167 gallbladder cancer cases and 184 controls. Genotyping was done by polymerase chain reaction-restriction fragment length polymorphism. Risk was estimated using unconditional logistic regression.

RESULTS

Significant risk was observed in the presence of PTGS2 -1195GA (P=0.006; odds ratio=2.00; 95% confidence interval=1.2-3.3) and AA genotypes (P=0.050; odds ratio=2.98; 95% confidence interval=1.0-8.9). Combined risk due to GA+AA genotypes was 2.12 (P=0.002; 95% confidence interval=1.3-3.3; P-trend=0.001). Sub-grouping showed a risk due to the PTGS2 -1195(GA+AA) genotype in males (P=0.007; odds ratio=2.97; 95% confidence interval=1.3-6.5), patients without gallstones (P=0.001; odds ratio=2.53; 95% confidence interval=1.4-4.7) and with late-onset gallbladder cancer (P=0.012; odds ratio=1.99; 95% confidence interval=1.1-3.4). Gallbladder cancer patients who used tobacco were at increased risk in the presence of the PTGS2 -765GC genotype (P=0.018; odds ratio=2.96; 95% confidence interval=1.2-7.2).

DISCUSSION

An association of PTGS2 -1195G>A polymorphism with gallbladder cancer, particularly in patients without gallstones, suggests a direct role of PTGS2 in cancer development.

-765G>C and 8473T>C polymorphisms of COX-2 and cancer risk: a meta-analysis based on 33 case-control studies

Cyclooxygenase-2 (COX-2) is an inducible enzyme converting arachidonic acid to prostaglandins and playing important roles in cancer etiology. The -765G>C and 8473T>C polymorphisms have been implicated in cancer risk. However, the results on the association between the two COX-2 polymorphisms and cancer risk are conflicting. To derive a more precise estimation of the association between them, we performed a meta-analysis of 8,090 cancer cases and 11,010 controls concerning -765G>C polymorphism and 14,283 cancer cases and 15,489 controls concerning 8473T>C polymorphism from 33 case-control studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. Overall, individuals with the -765GC or GC/CC genotypes were associated with higher cancer risk than those with the -765GG genotype and in the stratified analysis this effect maintained in colorectal carcinoma or esophageal cancer of Asian descents. Overall, no significant cancer risk of 8473T>C polymorphism was found. Stratified by cancer types, the variant 8473CC was associated with a decreased risk in breast cancer, compared with the TT or TC/TT genotypes and in lung cancer subgroup after sensitive analysis, there was a decreased risk in CC versus TT, TC versus TT and the dominant models. Moreover, a decreased risk of lung cancer was observed among smokers in the dominant model. In summary, this meta-analysis suggesting that -765G>C may cause an increased risk of colorectal carcinoma and esophageal cancer in Asian descents while 8473T>C polymorphism may cause a decreased risk of breast and lung cancer.

Common polymorphisms in the prostaglandin pathway genes and their association with breast cancer susceptibility and survival

PURPOSE

There is evidence that genetic variation in the prostaglandin pathway affects cancer susceptibility and progression. Conflicting data from several studies exist for the association of PTGS2 (cyclooxygenase 2) polymorphisms with breast cancer risk. We investigated associations between common germ-line variations in seven genes in the prostaglandin pathway and breast cancer susceptibility and survival among women with invasive breast cancer in the SEARCH study.

EXPERIMENTAL DESIGN

DNA samples from 9,030 cases and controls were genotyped for 64 single nucleotide polymorphisms tagging known common variants (minor allele frequency > 0.05) in PTGS1, PTGS2, TBXAS1, PTGIS, PTGES, PTGDS, and PGDS with a two-stage case-control study design.

RESULTS

Four tagging single nucleotide polymorphisms showed modest association with breast cancer susceptibility. All four fit a recessive genetic model. Minor allele homozygotes for PTGISrs5602 [odds ratio (OR), 1.15; 95% confidence interval (95% CI), 1.04-1.27; P = 0.005], PTGISrs8183919 (OR, 1.22; 95% CI, 1.06-1.41; P = 0.006), and TBXASrs41727 (OR, 1.83; 95% CI, 1.22-2.73; P = 0.003) are associated with an increased risk compared with common allele carriers. For PTGISrs44627 minor allele homozygotes (OR, 0.66; 95% CI, 0.5-0.86; P = 0.002), a protective effect was observed.

CONCLUSION

Specific PTGIS and TBXAS1 variants may affect breast cancer susceptibility, but common variants in PTGS1, PTGS2, PTGES, PTGDS, and PGDS have no major role in breast cancer susceptibility. None of the variants in the seven genes studied appear to affect survival. Further larger studies correlating clinical and genotypic data are required to establish if the clinical utility of prostaglandin-targeted therapies, as chemoprevention agents, is influenced by an individual's profile of genetic variants in key prostaglandin pathway genes.

Functional polymorphisms of cyclooxygenase-2 (COX-2) gene and risk for esophageal squmaous cell carcinoma

Cyclooxygenase-2 (COX-2) influences carcinogenesis through regulation of angiogenesis, apoptosis and cytokine expression. We aimed to evaluate association of COX-2 polymorphisms with predisposition to esophageal squamous cell carcinoma (ESCC), its phenotype variability and modulation of environmental risk in northern Indian population. We genotyped 174 patients with ESCC and 216 controls for COX-2 gene polymorphisms (-765G>C; -1195G>A; -1290A>G; 3'UTR 8473T>C) using PCR-RFLP. Data were statistically analyzed using chi-square test and logistic regression model. COX-2 -765C allele carriers were at increased risk for ESCC (OR=1.66; 95% CI=1.08-2.54; P=0.004). However, -1195G>A; -1290A>G; 3'UTR 8473T>C polymorphisms of COX-2 gene were not significantly associated with ESCC. We observed significantly enhanced risk for ESCC due to interaction between COX-2 -1195GAx-765GC+CC genotypes (OR=4.60; 95% CI=1.63-13.01; P=0.004). High risk to ESCC was also observed with respect to COX-2 haplotypes, A(-1290)G(-1195)C(-765)T(8473) and A(-1290)A(-1195)C(-765)T(8473) [OR=3.35; 95% CI=0.83-13.44; P=0.089; OR=4.28; 95% CI=0.43-42.40; P=0.246] however, it was not statistically significant. Stratification of subjects based on gender showed that females were at higher risk for ESCC due to COX-2 -765C carrier genotypes (OR=2.97; 95% CI=1.23-7.18; P=0.016). In association of genotypes with clinical characteristics, -765C carrier genotype conferred risk of ESCC in middle third of esophagus (OR=1.78; 95% CI=1.08-2.93; P=0.023). In case-only analysis, interaction of environmental risk factors and COX-2 genotypes did not further modulate the risk for ESCC. In summary, COX-2 -765G>C polymorphism confers ESCC susceptibility particularly in females and patients with middle third anatomical location of the tumor. Interaction of COX-2 -1195GA and -765C carrier genotypes also modulates ESCC risk.

Tpl-2/Cot and COX-2 in breast cancer

BACKGROUND

Breast cancer is the most common cancer in women worldwide and although mortality (129,000/year) stagnates, incidence (370,000/year) is increasing. In addition to histological type, grade, stage, hormonal and c-erbB2 status there is therefore a strong need for new and reliable prognostic and predictive factors.

METHODS AND RESULTS

This minireview focuses on two potential prognostic and predictive candidates Tpl2/Cot and COX-2 and summarise information about them.

CONCLUSION

Tumor progression locus 2 (Tpl2/Cot) is a serine/threonine protein kinase belonging to the family of MAP3 kinases. Activated Tpl2/Cot leads to induction of ERK1/2, JNK, NF-kappaB and p38MAPK pathways. The first study on Tpl2/Cot mRNA in breast cancer showed its increase in 40 % of cases of breast cancer but no available data exist on protein expression. Cyclo-oxygenase 2 (COX-2) is inducible by growth and inflammatory factors and contributes to the development of various tumours. Expression of COX-2 in breast cancer varied from 5-100 % in reviewed papers with significantly higher values in poorly differentiated tumours. Tpl2/Cot and COX-2 have their importance in different intracellular pathways and some of these are involved in cancer development. Briefly, the results from recent studies suggest that Tpl2/Cot and COX-2 could be prognostic factors in breast cancer.

Genetic susceptibility to cancer: the role of polymorphisms in candidate genes

CONTEXT

Continuing advances in genotyping technologies and the inclusion of DNA collection in observational studies have resulted in an increasing number of genetic association studies.

OBJECTIVE

To evaluate the overall progress and contribution of candidate gene association studies to current understanding of the genetic susceptibility to cancer.

DATA SOURCES

We systematically examined the results of meta-analyses and pooled analyses for genetic polymorphisms and cancer risk published through March 2008.

STUDY SELECTION

We identified 161 meta-analyses and pooled analyses, encompassing 18 cancer sites and 99 genes. Analyses had to meet the following criteria: include at least 500 cases, have cancer risk as outcome, not be focused on HLA antigen genetic markers, and be published in English.

DATA EXTRACTION

Information on cancer site, gene name, variant, point estimate and 95% confidence interval (CI), allelic frequency, number of studies and cases, tests of study heterogeneity, and publication bias were extracted by 1 investigator and reviewed by other investigators.

RESULTS

These 161 analyses evaluated 344 gene-variant cancer associations and included on average 7.3 studies and 3551 cases (range, 508-19 729 cases) per investigated association. The summary odds ratio (OR) for 98 (28%) statistically significant associations (P value <.05) were further evaluated by estimating the false-positive report probability (FPRP) at a given prior probability and statistical power. At a prior probability level of 0.001 and statistical power to detect an OR of 1.5, 13 gene-variant cancer associations remained noteworthy (FPRP <0.2). Assuming a very low prior probability of 0.000001, similar to a probability assumed for a randomly selected single-nucleotide polymorphism in a genome-wide association study, and statistical power to detect an OR of 1.5, 4 associations were considered noteworthy as denoted by an FPRP value <0.2: GSTM1 null and bladder cancer (OR, 1.5; 95% CI, 1.3-1.6; P = 1.9 x 10(-14)), NAT2 slow acetylator and bladder cancer (OR, 1.46; 95% CI, 1.26-1.68; P = 2.5 x 10(-7)), MTHFR C677T and gastric cancer (OR, 1.52; 95% CI, 1.31-1.77; P = 4.9 x 10(-8)), and GSTM1 null and acute leukemia (OR, 1.20; 95% CI, 1.14-1.25; P = 8.6 x 10(-15)). When the OR used to determine statistical power was lowered to 1.2, 2 of the 4 noteworthy associations remained so: GSTM1 null with bladder cancer and acute leukemia.

CONCLUSION

In this review of candidate gene association studies, nearly one-third of gene-variant cancer associations were statistically significant, with variants in genes encoding for metabolizing enzymes among the most consistent and highly significant associations.