Effect of rs6983267 polymorphism in the 8q24 region and rs4444903 polymorphism in EGF gene on the risk of sporadic colorectal cancer in Iranian population

Cumulative evidence of relationships between multiple variants in 8q24 region and cancer incidence

Genome-wide association studies (GWAS) have identified multiple independent cancer susceptibility loci at chromosome 8q24. We aimed to evaluate the associations between variants in the 8q24 region and cancer susceptibility. A comprehensive research synopsis and meta-analysis was performed to evaluate associations between 28 variants in 8q24 and risk of 7 cancers using data from 103 eligible articles totaling 146,932 cancer cases and 219,724 controls. Results: 20 variants were significantly associated with risk of prostate cancer, colorectal cancer, thyroid cancer, breast cancer, bladder cancer, stomach cancer, and glioma, including 1 variant associated with prostate cancer, colorectal cancer, and thyroid cancer. Cumulative epidemiological evidence of an association was graded as strong for DG8S737 -8 allele, rs10090154, rs7000448 in prostate cancer, rs10808556 in colorectal cancer, rs55705857 in gliomas, rs9642880 in bladder cancer, moderate for rs16901979, rs1447295, rs6983267, rs7017300, rs7837688, rs1016343, rs620861, rs10086908 associated in prostate cancer, rs10505477, rs6983267 in colorectal cancer, rs6983267 in thyroid cancer, rs13281615 in breast cancer, and rs1447295 in stomach cancer, weak for rs6983561, rs13254738, rs7008482, rs4242384 in prostate cancer. Data from ENCODE suggested that these variants with strong evidence and other correlated variants might fall within putative functional regions. Our study provides summary evidence that common variants in the 8q24 are associated with risk of multiple cancers in this large-scale research synopsis and meta-analysis. Further studies are needed to explore the mechanisms underlying variants in the 8q24 involved in various human cancers.

Single Nucleotide Variants Associated with Colorectal Cancer Among Iranian Patients: A Narrative Review

Colorectal cancer has been considered as one of the complicated multi-stage processes after adenoma-carcinoma sequence. Therefore, studies of the molecular dysregulation basis could present information on the recognition of the potent biomarkers and treatment targets for this disease. Even though outcomes of the patients with colorectal cancer have been improved largely with current annual screening plans, it is necessary to have reliable prognostic biomarkers because of the disease heterogeneity. There is a significant relationship between SNP in IL1RN* 2 (IL1ra), −509 C/T (TGFB1), rs11556218 T>G and rs4778889 T/C (IL16), miRNA-binding site polymorphisms in IL16, rs4464148 (SMAD7), rs6983267 (EGF), GSTT1, TACG haplotype (CTLA4), 1793G> A (MTHFR), Leu/Leu genotype of (EXO1), −137 G/C (IL18), C/T genotype (XRCC3), I3434T (XRCC7), MGMT, C3435T (MDR1), ff genotype of FokI, 677CT+TT (MTHFR), G2677T/A (MDR1) and CRC. Increased risk has been observed in VDR ApaI genotype “aa”. Finally, the protective effect has been explored in the TACA haplotype (CTLA4). According to the findings, the genetic polymorphisms in the immunity-associated genes are related to the CRC amongst the Iranian patients. Therefore, more large-scale functional investigations are necessary for confirming the results.

Single nucleotide polymorphism rs10889677 in miRNAs Let-7e and Let-7f binding site of IL23R gene is a strong colorectal cancer determinant: Report and meta-analysis

Single nucleotide polymorphisms (SNPs) in the recognition sites of microRNAs (miRNAs), located at 3' untranslated region (UTR) of mRNAs, interfere with posttranslational gene regulation. Deregulation of genes may contribute to some disease susceptibility including colorectal cancer (CRC). In the present study, in a case-control setup, 167 CRC patients and 161 control subjects were studied for allele and genotype frequency of rs10889677 polymorphism in miRNAs Let-7e and Let-7f binding sites at 3' UTR of IL23R gene using PCR-RFLP assay. Also, related articles were retrieved from MEDLINE, Cochrane review, Google Scholar and Scopus databases for meta-analysis study. According to our results, AA genotype of SNP rs10889677 was significantly correlated with increased risk of CRC (OR = 3.10; 95% CI [1.86-5.18]; P: < 0.001). In a meta-analysis on 10 risk estimates for the CC versus AA genotype, we found an inverse association between CC SNPs and risk of all cancer (OR = 0.59; 95% CI [0.49-0.71]; P < 0.001). In conclusion, our results demonstrate that rs10889677 polymorphism is significantly associated with CRC risk.

The association between EGF A61G polymorphism and risk of colorectal cancer in a Chinese population: a case-control study

Epidermal Growth factor (EGF) could induce colorectal cancer (CRC) cell to develop epithelial mesenchymal-transition and enhance their ability to invade and migrate. Several studies have thrown light on the association between EGF gene polymorphism and risk of CRC, but with conflicting results. Therefore, we determined EGF A61G polymorphism by using PCR-restriction fragment length polymorphism method in 341 CRC cases and 472 controls in a Chinese population. Our results showed that EGF A61G polymorphism increased the risk of CRC in a Chinese population (GG vs AA: adjusted OR: 1.92; 95% CI: 1.27–2.91; P=0.002; GG+AG vs AA: adjusted OR: 1.43; 95% CI: 1.05–1.94; P=0.022; GG vs AG+AA: adjusted OR: 1.65; 95% CI: 1.15–2.39, P=0.007; G vs A: OR: 1.39; 95% CI: 1.14–1.69, P=0.001). Stratified analyses revealed that the significant association was more evident in the females, smokers, drinkers, and old subjects (age ≥60 years). Furthermore, the GG and/or AG genotype carriers were more likely to have larger tumor size and lymph node metastasis. In conclusion, EGF A61G polymorphism is a genetic contributor to CRC in a Chinese Han population.

The genetic association between EGF A61G polymorphism (rs4444903) and risk of colorectal cancer: An update meta-analysis and trial sequential analysis

BACKGROUND

Colorectal cancer was a complex disease with multiple causative factors including genetic and environmental factors, as well as the interaction of the 2 factors. Relationship between epidermal growth factor (EGF) A61G polymorphism and colorectal cancer risk has been widely investigated previously, whereas results derived from these studies were inconclusive and controversial. The aim of this study was to investigate the association between the EGF A61G polymorphism and colorectal cancer using a meta-analysis of existing literature.

METHODS

Literature search was conducted from PubMed, EMBASE, China National Knowledge Infrastructure, Wanfang, and Cochrane library databases before July 2017. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the strength of the association between EGF A61G and colorectal cancer.

RESULTS

A total of 9 studies that involved 1448 cases and 1928 healthy controls and found allelic (OR = 1.18, P = .04) and recessive models (OR = 1.36, P = .03) of EGF A61G were significantly associated with the risk of colorectal cancer. Stratification analyses by ethnicity indicated that the EGF 61G significantly increased the risk of colorectal cancer in the Caucasian subgroup (OR = 1.24, P = .02), but not in Asian subgroup (OR = 1.12, P = .08). And the frequency of GG genotype of EGF A61G significantly increased in cases than that in healthy controls in both Caucasian (OR = 1.40, P = .04) and Asian subgroups (OR = 1.27, P = .01). Furthermore, the sample sources and genotyping methods seem to have no influence on the correction of EGF A61G and colorectal cancer susceptibility (P > .05).

CONCLUSION

The results indicate that EGF A61G might increase the risk of colorectal cancers.

Association between lncRNA CASC8 polymorphisms and the risk of cancer: a meta-analysis

Objective

To explore the relationship between single-nucleotide polymorphisms (SNPs) in one of the long noncoding RNA (lncRNA), cancer susceptibility candidate 8 (CASC8) gene and the risk of cancer.

Materials and methods

A meta-analysis was conducted to summarize the relationship between common SNPs (rs10505477 and rs7837328) in the lncRNA CASC8 gene and the risk of cancer. The relevant references were retrieved from several authoritative databases. Rigorous inclusion and exclusion criteria were adopted to ensure the credibility of the results. The fixed effects or random effects model was used to calculate the OR and 95% CI. We tested for publication bias.

Results

Fifteen articles containing 20 datasets (24,504 cases and 22,969 controls) were finally included in the meta-analysis. Compared to the individuals carrying the rs10505477 TT genotype, those with the TC or CC genotype had a decreased risk of cancer (TC vs TT: OR 0.876, 95% CI 0.832–0.923, P<0.001; CC vs TT: OR 0.748, 95% CI 0.703–0.795, P<0.001). Allele C of rs10505477 might be a protective factor for decreasing susceptibility to cancer (OR 0.866, 95% CI 0.840–0.893, P<0.001). As for rs7837328, the GA and AA genotypes were associated with increased risks of cancer as compared to the GG genotype (ORs 1.209 and 1.336; 95% CIs 1.127–1.298 and 1.202–1.484, respectively); its A allele could significantly increase the risk of cancer compared with the G allele (OR 1.169, 95% CI 1.114–1.227, P<0.001).

Conclusion

The rs10505477 and rs7837328 polymorphisms might be associated with risk of cancer.

Cumulative evidence for relationships between multiple variants in 8q24 and colorectal cancer incidence

Genome-wide association studies (GWAS) have identified multiple independent cancer susceptibility loci at chromosome 8q24.We conducted a comprehensive research synopsis and meta-analysis to evaluate associations between 6 variants in 8q24 and risk of colorectal cancer using data from 31 eligible articles totaling 41,942 cases and 49,968 controls.Of the 6 variants located in 8q24, 3 were significantly associated with risk of colorectal cancer. In particular, both homozygous TT and heterozygous CT genotypes of rs10505477, as well as the GG and TG genotypes of rs6983267, were associated with risk of colorectal cancer.Our study provides summary evidence that common variants in the 8q24 are associated with risk of colorectal cancer in this large-scale research synopsis and meta-analysis. Further studies are needed to explore the exact role of the variants in the 8q24 involved in the etiology of colorectal cancer.

Association of rs6983267 at 8q24, HULC rs7763881 polymorphisms and serum lncRNAs CCAT2 and HULC with colorectal cancer in Egyptian patients

The impact of HULC rs7763881 on colorectal cancer (CRC) susceptibility is not yet known. Also, the biological function of the cancer-related rs6983267 remains unclear. We investigated the association of these SNPs with the risk of CRC and adenomatous polyps (AP), their correlation with CCAT2 and HULC expression, and the potential of serum CCAT2 and HULC as biomarkers for CRC. 120 CRC patients, 30 AP patients, and 96 healthy controls were included. Genotyping and serum lncRNAs were assayed by qPCR. Studied SNPs were not associated with AP susceptibility. rs6983267 GG was associated with increased CRC risk, whereas rs7763881 AC was protective. rs7763881 and rs6983267 CT haplotype was protective. Serum CCAT2 and HULC were upregulated in CRC and AP patients versus controls and discriminated these groups by ROC analysis. rs6983267 GG and rs7763881 AA patients demonstrated higher serum CCAT2 and HULC compared with GT/TT and AC, respectively. rs6983267 and serum HULC predicted CRC diagnosis among non-CRC groups (AP + controls) by multivariate analysis. Studied SNPs or serum long noncoding RNAs weren't correlated with nodal or distant metastasis. In conclusion, rs6983267 and rs7763881 are potential genetic markers of CRC predisposition and correlate with serum CCAT2 and HULC, two novel potential non-invasive diagnostic biomarkers for CRC.

Polymorphism (rs16917496) at the miR-502 Binding Site of the Lysine Methyltransferase 5A (SET8) and Its Correlation with Colorectal Cancer in Iranians

Background:

One of the gene expression regulatory mechanisms is mediated by small noncoding RNAs called microRNA (miRNA). They interact with a recognition sequence located mostly in 3’-untranslated regions (3’-UTRs) of mRNAs. Polymorphisms in miRNAs recognition sequences could affect gene expression which in turn may alter disease susceptibility. SET8, a member of the SET domain-containing methyltransferase, acts in a variety of biological processes such as genomic stability. Here, we report correlation of rs16917496 polymorphism, located in the recognition sequence of miR-502 within 3’-UTR of SET8, with colorectal cancer (CRC) in Iranians.

Materials and Methods:

One hundred and seventy CRC patients and 170 noncancer counterparts were recruited in this case–control study. Genotyping of rs16917496 was performed using polymerase chain reaction-restriction fragment length polymorphism method.

Results:

There was no significant association of rs16917496 with CRC in population under study (P value for genotype and allele distribution were >0.05). However, stratification analysis based on smoking status revealed that TT+TC genotypes of SET8 rs16917496 are strongly associated with increased risk of CRC (odds ratio: 5.8, 95% confidence interval: 1.37–24.34, P - 0.005) in smoker subgroup.

Conclusion:

Correlation of rs16917496 T allele with CRC in smokers is emphasizing the importance of individuals’ genotype in the recruitment of adverse health hazards of smoking more profoundly for certain people compared to others.

Association between 8q24 rs6983267 polymorphism and cancer susceptibility: a meta-analysis involving 170,737 subjects

Published data on the association between 8q24 rs6983267 polymorphism and cancer risk are inconsistent. Thus, we conducted a meta-analysis to evaluate the relationship between rs6983267 polymorphism and cancer risk. We searched on PubMed, EMBASE, Web of Science and China National Knowledge Infrastructure (CNKI) up to November 1, 2016 for relevant studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to estimate the strength of this association. We included 78 case-control studies with a total of 73,996 cases and 96,741 controls in this meta-analysis. The pooled results showed that rs6983267 polymorphism was significantly associated with increased risk of overall cancer in all genetic models (dominant model: OR = 1.19, 95% CI = 1.13–1.26; recessive model: OR = 1.19, 95% CI = 1.14–1.25; homozygous model: OR= 1.31, 95% CI = 1.23–1.40; heterozygous model: OR = 1.14, 95% CI = 1.10–1.19; allelic model: OR = 1.14, 95% CI = 1.11–1.18). Stratified analyses indicated that rs6983267 significantly increased the risk of colorectal cancer in Caucasians, prostate cancer in Caucasians and Asians, thyroid cancer in Caucasians and lung cancer in Asians. When studies were stratified by study quality, source of controls and genotyping method, significant associations were especially found in the high quality studies, the publication-based studies, the hospital-based studies, and the PCR-RFLP studies. Additional well-designed studies with large samples should be performed to validate our results.

DNA methylation analysis of secreted frizzled-related protein 2 gene for the early detection of colorectal cancer in fecal DNA

Background:

The early detection of colorectal cancer (CRC) with high sensitivity screening is essential for the reduction of cancer-specific mortality. Abnormally methylated genes that are responsible for the pathogenesis of cancers can be used as biomarkers for the detection of CRC. The methylation status of the secreted frizzled-related protein 2 (SFRP2) gene was evaluated for their use as a marker in the noninvasive detection of CRC.

Materials and Methods:

Methylation-specific polymerase chain reaction was performed to analyze the promoter CpG methylation of SFRP2 in the fecal DNA of 25 patients with CRC and 25 individuals exhibiting normal colonoscopy results.

Results:

Promoter methylation levels of SFRP2 in CRC patients and in healthy controls were 60% and 8%, respectively. Methylation of the SFRP2 promoter in fecal DNA is associated with the presence of colorectal tumors.

Conclusion:

Hence, the detection of aberrantly methylated DNA in fecal samples may present a promising, noninvasive screening method for CRC.

Clinical Significance of Long Non-Coding RNA CASC8 rs10505477 Polymorphism in Lung Cancer Susceptibility, Platinum-Based Chemotherapy Response, and Toxicity

Long non-coding RNA (lncRNA) CASC8 rs10505477 polymorphism has been identified to be related to risk of many kinds of cancers, such as colorectal cancer, gastric cancer, and invasive ovarian cancer, and it may be involved in the prognosis of gastric cancer patients who have received platinum-based chemotherapy after surgical treatment. So far, there is no study investigating the clinical significance of lncRNA CASC8 rs10505477 in lung cancer susceptibility and treatment. In this study, we genotyped 498 lung cancer patients and 213 healthy control subjects to explore the correlation between the rs10505477 polymorphism and lung cancer risk in a Chinese population. Among the 498 patients, 467 were selected for the chemotherapy response and toxicity study. We found that the single nucleotide polymorphisms (SNP) rs10505477 was greatly related to lung cancer risk in male and adenocarcinoma subgroups in recessive model (adjusted OR = 0.51, 95%CI = 0.29–0.90, p = 0.02; adjusted OR = 0.52, 95%CI = 0.30–0.89, p = 0.02, respectively). It was also closely correlated with platinum-based chemotherapy response in dominant model (adjusted OR = 1.58, 95%CI = 1.05–2.39, p = 0.03). Additionally, we observed that CASC8 rs10505477 polymorphism was significantly relevant to severe hematologic toxicity in non-small-cell lung cancer (NSCLC) subgroup in dominant model (adjusted OR = 0.59, 95%CI = 0.35–0.98, p = 0.04) and in additive model (adjusted OR = 0.62, 95%CI = 0.43–0.90, p = 0.01). Furthermore, it was found that rs10505477 polymorphism was greatly associated with gastrointestinal toxicity in SCLC and cisplatin subgroups in dominant model (adjusted OR = 7.82, 95%CI = 1.36–45.07, p = 0.02; adjusted OR = 1.94, 95%CI = 1.07–3.53, p = 0.03, respectively). Thus, lncRNA CASC8 rs10505477 could serve as a possible risk marker for diagnosing lung cancer, and could be used to forecast the response and toxicity of platinum-based treatment in lung cancer patients.

Pluripotency transcription factors in the pathogenesis of colorectal cancer and implications for prognosis

The cancer stem cell hypothesis argues that cancers depend on a specific type of cells, representing usually a small percentage of the total cancer cell population, termed cancer stem cells (or tumor-initiating cells) for their development and propagation. In colorectal cancer these cells express specific surface proteins such as CD133 and CD44 and can recapitulate the whole tumor. Besides expression of these surface markers, stem cells are associated with a network of pluripotency transcription factors, such as Oct4 and Sox2, which is present in them. Pluripotency factors are normally active in early development and characterize primitive cells, able to give rise to all different cell and tissue types of the three embryonic layers. In this review I will discuss the relationship of these factors with pathogenic lesions in colorectal cancer and their prognostic implications.

Methylation pattern of ALX4 gene promoter as a potential biomarker for blood-based early detection of colorectal cancer

BACKGROUND

To develop a non-invasive screening method for colorectal cancer, we evaluated the methylation of ALX4 gene promoter in serum samples from patients with colorectal cancer (CRC) and equal number of healthy individuals.

MATERIALS AND METHODS

In serum samples from 25 patients with colorectal cancer and 25 healthy control subjects, isolated serum free-floating DNA was treated with sodium bisulfite and analyzed by methylation-specific polymerase chain reaction (MSP) with primers specific for methylated or unmethylated promoter CpG island sequences of the ALX4 gene.

RESULTS

Methylation of the ALX4 gene promoter was present in the serum DNA of patients with adenoma and colorectal cancer. A sensitivity of 68% and specificity of 88% were achieved in the detection of promoter methylation in colorectal neoplasia samples. The difference in methylation status of the ALX4 promoter between the patients with colorectal neoplasia and the control group was statistically highly significant (P < 0.001).

CONCLUSIONS

The results indicate that this serum free DNA test of methylation of the ALX4 gene promoter is a sensitive and specific method. Therefore in combination with other useful markers it seems ALX4 has the potential of a clinically useful test for the early detection of colorectal cancer.

Early detection of colorectal cancer: from conventional methods to novel biomarkers

PURPOSE

Colorectal cancer (CRC) is one of the major health problems worldwide and is often diagnosed at late stage. There is growing body of evidence in early detection of this disease with novel screening modalities to reduce compliance and increase specificity of available methods. The aim of current review is to give an overview on currently available screening methods (e.g., fecal occult blood testing (FOBT), flexible sigmoidoscopy, and colonoscopy), with their own merits and disadvantages, and new genetic/epigenetic/protein markers, as novel screening modalities.

RESULT

There are several serum and fecal biomarkers that can predict CRC and polyps. Overall sensitivities for detection by fecal DNA markers ranged from 53 to 87%, while a panel of serum protein markers provides a sensitivity/specificity up to 85% for CRC. In particular, DNA methylation markers (e.g., SEPT9, SFRP2, and ALX4), circulating microRNAs (e.g., microRNA21), SNPs in microRNAs binding site (e.g., rs4596 located within a target region of the predicted miR-518a-5p and miR-527), protein markers (e.g., carcinoembryonic antigen, N-methyltransferase), or microsatellites instability in tumors with deficient mismatch repair of some genes are among the most interesting and promising biomarkers.

CONCLUSION

Increasing evidence supports the use of combined fecal and serum biomarkers with sigmoidoscopy and colonoscopy screening in order to maximize the benefits and reduce the number of false-positive tests and patients undergoing invasive methods, which in turn could overcome the limitations of the current screening methods for early detection of CRC and adenomas.

A miRNA-binding site single nucleotide polymorphism in the 3'-UTR region of the NOD2 gene is associated with colorectal cancer

Colorectal cancer (CRC) is one of the common malignancies worldwide. Single nucleotide polymorphisms in miRNA-binding site on gene transcripts are reported to play important role in increased risk of CRC in different population. We performed a case-control study using 88 CRC patients and 88 non-cancer counterparts to evaluate the association between NOD2 rs3135500 polymorphism located at 3' untranslated region of the gene and risk of sporadic CRC. Genotyping of rs3135500 polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. We found a significant association of AA genotype with risk of CRC (adjusted OR 3.100, CI 1.621-5.930, p < 0.001). Also, significant difference in physical activity (p = 0.001) between case and control groups was found. We also found that individuals in control group were more aspirin or NSAID user compared to sporadic CRC cases (p = 0.002). In the case group, individuals with GG genotype consumed more aspirin or NSAID compared with AA+AG genotypes (33.3 vs. 9.6 %, adjusted OR 4.71, CI 1.25-17.76, p = 0.02). However, in the control group, individuals with AA+AG genotypes used more aspirin or NSAID compared with GG genotypes (47.2 vs. 11.4 %, adjusted OR 14 %, CI 0.05-0.47, p < 0.001).

Common variation rs6983267 at 8q24.1 and risk of colorectal adenoma and cancer: evidence based on 31 studies

Genome-wide association studies have identified 8q24.21-rs6983267 as a new colorectal cancer (CRC) and colorectal adenoma (CRA) susceptibility locus in populations of European descent. Since then, the relationship between 8q24.21-rs6983267 and CRC/CRA has been reported in various ethnic groups; however, these studies have yielded inconsistent results. To investigate this inconsistency and derive a more precise estimation of the relationship, we conducted a meta-analysis of 31 studies, including 51,293 cases and 58,962 controls for CRC, and 8,148 cases and 17,065 controls for CRA. Potential sources of heterogeneity and publication bias were also systematically explored. Overall, the summary odds ratio of G variant for CRC was 1.18 (95% CI, 1.16-1.21; P < 10(-5)) and 1.17 (95% CI, 1.11-1.23; P < 10(-5)) for CRA. Significant results were observed using dominant or recessive genetic model for the polymorphism. In the subgroup analysis by ethnicity, significantly increased risks were found in East Asians and Caucasian populations; while no significant associations were detected among African Americans. After stratifying by sample size and control source, significant associations were also obtained. This meta-analysis suggests that the 8q24.21-rs6983267 polymorphism is associated with CRC/CRA susceptibility, but these associations vary in different ethnic populations.

Methylation pattern of SFRP1 promoter in stool sample is a potential marker for early detection of colorectal cancer

Background:

To setup a non-invasive genetic screening method for colorectal cancer, we evaluated the promoter methylation status of secreted frizzled-related protein1 (sfrp1) in stool samples of colorectal cancer with respect to a series of healthy individuals, using methylation-specific polymerase chain reaction.

Materials and Methods:

In stool samples from 25 patients with colorectal cancer and 25 healthy control subjects, isolated DNA was treated with sodium bisulfite and analyzed by methylation-specific polymerase chain reaction with primers specific for methylated or unmethylated promoter sequences of the SFRP1 gene.

Result:

Methylation of the SFRP1 promoter was present in the stool DNA of patients with colorectal cancer. A sensitivity of 52% and specificity of 92% were achieved in the detection of colorectal neoplasia. The difference in methylation status of the SFRP1 promoter between the patients with colorectal neoplasia and the control group was statistically highly significant (P = 0.006).

Conclusions:

The results indicate that this DNA stool test of methylation of the SFRP1 promoter is a sensitive and specific method. It is assumed that the test is potentially useful for the early detection of colorectal cancer.

Polymorphisms on 8q24 are associated with lung cancer risk and survival in Han Chinese

Chromosome 8q24 is commonly amplified in many types of cancer, particularly lung cancer. Polymorphisms in this region are associated with risk of different cancers. To investigate the relationship between three single nucleotide polymorphisms (SNPs) (rs1447295, rs16901979 and rs6983267) on 8q24 and lung cancer risk, we conducted an association study in two Han Chinese populations: one population was from Zhejiang Province (576 case patients and 576 control subjects), whereas the other was from Fujian Province (576 case patients and 576 control subjects). We found that rs6983267 was significantly associated with an increased risk of lung cancer in both populations. Compared with the TT genotype, the GG genotype was associated with a significant 1.555-fold increased risk of lung cancer [95% confidence interval (CI) 1.218-1.986, P = 4.0×10(-4)]. This effect was more pronounced in never-smokers [odds ratio (OR) = 2.366, 95% CI 1.605-3.488, P = 1.4×10(-5)]. Analyses stratified by histology revealed that rs6983267 GG genotype was most associated with patients with other histological types (OR = 3.012, 95% CI 1.675-5.417, P = 2.3×10(-4)). The AA genotype of rs1447295 was associated with increased risk for adenocarcinoma compared with the CC genotype (OR = 2.260, 95% CI 1.174-4.353, P = 0.015). Furthermore, the GG genotype of rs6983267 was associated with worse survival in the Zhejiang population (hazard ratio (HR) = 1.646, 95% CI 1.099-2.464, P = 0.016). No association was observed for rs16901979. These results suggest that genetic variations on 8q24 may play significant roles in the development and progression of lung cancer.

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

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

Meta-analysis of epidermal growth factor polymorphisms and cancer risk: involving 9,779 cases and 15,932 controls

The epidermal growth factor (EGF) pathway stimulates proliferation and differentiation of epidermal and epithelial tissues, and plays an important role in tumorigenesis. The association between EGF polymorphisms and cancer risk is controversial; thus, we performed this meta-analysis. Overall, 41 case-control studies with 9,779 cases and 15,932 controls were retrieved. We found that EGF +61A/G polymorphism increased overall cancer risk (G allele vs. A allele: OR=1.181, 95% CI=1.077-1.295, P(heterogeneity) < 0.001; GG vs. AA: OR=1.370, 95% CI=1.143-1.641, P(heterogeneity) < 0.001; GG+GA vs. AA: OR=1.175, 95% CI=1.047-1.318, P(heterogeneity) < 0.001). In the stratified analysis by cancer type, the +61 G allele was a risk factor for colorectal cancer, esophageal carcinoma, gastric cancer, and hepatocellular carcinoma. Individuals who carried +61G allele had higher cancer susceptibility in mixed and European racial subgroups. An increased association was detected in the hospital-based subgroup. No significant association was found among EGF -1380A/G, -1744G/A, rs6983267T/G polymorphisms and cancer risk.