Associations between variants of the 8q24 chromosome and nine smoking-related cancer sites

Polymorphisms in lncRNA CCAT1 on the susceptibility of lung cancer in a Chinese northeast population: A case-control study

OBJECT

To explore the association of rs1948915, rs7013433 in long noncoding RNA (lncRNA) CCAT1 and rs6983267 in MYC enhancer region with the risk of lung cancer in a Chinese northeast population, a case-control study was conducted.

METHODS

The hospital-based case-control study contained 669 lung cancer patients and 697 healthy controls. Taqman® Probe allele resolution was used for genotyping. The differences between the case-control groups were analyzed using Student t-test and chi-square test. Logistic regression analysis was used to assess the relationship between the genotypes and the risk of lung cancer. Cross-generation analysis was used to explore the relationship between gene-environment interaction and lung cancer.

RESULTS

There was no association between the three selected single-nucleotide polymorphisms (SNPs) and the susceptibility of lung cancer. Rs1948915 CT was correlated with lung adenocarcinoma. In female stratification, rs1948915 CT/CC was associated with a decreased susceptibility of lung cancer significantly. Additionally, the additive and multiplicative interaction models showed that there was no interaction between the three selected SNPs and smoking status in lung cancer.

CONCLUSIONS

There may be an association between lung adenocarcinoma and rs1948915 polymorphism in the Chinese northeast population, while rs7013433 and rs6983267 might have no association. There was no interaction between the three selected SNPs and smoking status.

Investigating the association between rs6983267 polymorphism and susceptibility to gastrointestinal cancers in Iranian population

Genome-wide association studies have revealed that some single nucleotide polymorphisms at 8q24, such as rs6983267, might be effective in susceptibility to various cancers in different populations. Therefore, rs6983267 might be useful as a marker for multiple cancers. In this study, we considered a population, including 478 gastrointestinal cancer cases from the Iranian population, to investigate the association between rs6983267 and susceptibility to gastrointestinal cancers. The samples were genotyped using the TaqMan real-time PCR method while 10% of them were also confirmed by sequencing. Higher frequency of G allele was associated with higher grades of tumors in esophageal cancer and the tumors located in the lower portion of the esophagus (OR 3.56; 95% CI 1.13-11.24; P = 0.03) and cardia (OR 5.24; 95% CI 1.26-21.83; P = 0.02), which both locations are involved in esophageal adenocarcinomas with poor prognosis. The results indicated that in the male subgroup, the rs6983267 GG genotype significantly enhanced the gastric cancer susceptibility (OR 4.76; 95% CI 1.57-14.45; P = 0.01). GG genotype also increased the risk of intestinal-type gastric cancer, located in non-cardia (OR 4.62; 95% CI 1.25-17.04; P = 0.02). Moreover, gastric cancer cases and controls with a family history of gastrointestinal tumors were mostly genotyped with the G allele (OR 3.61; 95% CI = 1.09-12.01; P = 0.04). There were no remarkable associations between rs6983267 and susceptibility to esophageal and colon cancers in the Iranian population. However, different genotypes of rs6983267 had significant correlations with tumor grade, cancer type, and family history of gastrointestinal cancers. Further investigations in a larger population and other ethnicities are required to confirm these results.

Associations between lncRNA-related polymorphisms and hepatocellular carcinoma risk: A two-stage case-control study

BACKGROUND AND AIM

Single-nucleotide polymorphisms (SNPs) in long non-coding RNAs (lncRNAs) are potential biomarkers for cancer risk, but their association with hepatocellular carcinoma (HCC) is unclear. We examined the association of lncRNA-related SNPs with HCC susceptibility and explored the optimal genetic models for SNPs.

METHODS

Five candidate SNPs linked with digestive tumors were first genotyped in a screening population of 700 HCC and 2800 control cases. The association between each SNP and HCC risk was estimated by multivariate logistic regression adjusted by sex and age and recorded as odds ratio (OR) with 95% confidence interval. Significant associations were further tested in a validation population with 1140 HCC and 5115 control cases. Finally, the most appropriate genetic models for HCC-associated SNPs were identified using pairwise allele differences; the overall gene effects of each SNP were further evaluated based on optimal genetic models.

RESULTS

Three candidate SNPs, rs7315438, rs6983267, and rs10795668, showed statistical connections with HCC risk in the discovery stage. Among these, rs7315438 remained steadily significant in the validation stage; rs7315438 and rs10795668 both reached statistical threshold in the combined analysis of both stages. SNP rs7315438 (TC vs TT/CC, OR = 1.410, P < 0.001) was associated with increased risk of HCC in a complete overdominant model, whereas rs10795668 (AG vs AA/GG, OR = 0.892, P = 0.035) exerted a protective effect on HCC risk in a complete overdominant model.

CONCLUSIONS

Long non-coding RNA-related SNPs rs7315438 and rs10795668 are potential biomarkers for HCC susceptibility, especially when evaluated based on their optimal genetic models.

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.

Genetic variations at 8q24 and gastric cancer susceptibility: A meta-analysis study

BACKGROUND

Published data on the association between genetic variants on the 8q24 chromosome and gastric cancer (GC) susceptibility are inconclusive. Here we present a meta-analysis designed to evaluate the relationship between 8q24 variants (single nucleotide polymorphisms (SNPs) labeled rs6983267 and rs1447295) and risk of developing GC.

METHODS

A literature search was performed using studies published on PubMed, Science Direct, OVID and Web of Science databases up to December 2016. Studies were selected based on our enrollment criteria, relevant data was extracted from each study and the odds ratios (OR), and 95% confidence intervals (CI) were calculated and used to assess the strength of associations found between 8q24 polymorphisms and GC risk. Conclusions about acceptable strong associations were made after taking into account sample heterogeneity and sensitivity analyses.

RESULTS

A total of seven studies containing ten case-control studies were selected. Among these studies were six studies of 1,421 GC patients and 3,393 controls examining the role of the rs6983267 SNP and four studies including 779 cases and 1,266 controls examining rs1447295 SNP. The pooled results of these studies indicated that there was no significant association between both genetic variants and GC susceptibility using an allele, dominant, recessive and homozygote genetic models. When using a heterozygote genetic model, a significant increase was found in the association of GC risk for rs6983267 SNP (OR = 1.07, 95% CI = 1.01-1.12, P = 0.015), whereas for rs1447295 SNP a significant decreased risk was detected (OR = 0.82, 95% CI = 0.69-0.98, P = 0.030). In subgroup analyses based on ethnicity and genotyping methods, similar non-significant results were observed for the rs1447295 variant using the four genetic models (allele, dominant, recessive or homozygote models) and for the rs6983267 variant using only the allele, recessive and homozygote models. However, after a multiple testing correction to our calculations, these associations remained non-significant.

CONCLUSION

Meta-analysis of gastrointestinal cancer genetic analysis studies did not confirm an association between 8q24 chromosome polymorphisms (specifically rs6983267 and rs1447295) and susceptibility to GC in the general populations.

Inherited pancreatic cancer

Pancreatic cancers arise through a series of genetic events both inherited and acquired. Inherited genetic changes, both high penetrance and low penetrance, are an important component of pancreatic cancer risk, and may be used to characterize populations who will benefit from early detection. Furthermore, pancreatic cancer patients with inherited mutations may be particularly sensitive to certain targeted agents, providing an opportunity to personalized treatment. Family history of pancreatic cancer is one of the strongest risk factors for the disease, and is associated with an increased risk of caners at other sites, including but not limited to breast, ovarian and colorectal cancer. The goal of this chapter is to discuss the importance of family history of pancreatic cancer, and the known genes that account for a portion of the familial clustering of pancreatic cancer.

Environmental factors and risk of aggressive prostate cancer among a population of New Zealand men - a genotypic approach

Prostate cancer is one of the most significant health concerns for men worldwide. Numerous researchers carrying out molecular diagnostics have indicated that genetic interactions with biological and behavioral factors play an important role in the overall risk and prognosis of this disease. Single nucleotide polymorphisms (SNPs) are increasingly becoming strong biomarker candidates to identify susceptibility to prostate cancer. We carried out a gene × environment interaction analysis linked to aggressive and non-aggressive prostate cancer (PCa) with a number of SNPs. By using this method, we identified the susceptible alleles in a New Zealand population, and examined the interaction with environmental factors. We have identified a number of SNPs that have risk associations both with and without environmental interaction. The results indicate that certain SNPs are associated with disease vulnerability based on behavioral factors. The list of genes with SNPs identified as being associated with the risk of PCa in a New Zealand population is provided in the graphical abstract.

Emergence of the Noncoding Cancer Genome: A Target of Genetic and Epigenetic Alterations

The emergence of whole-genome annotation approaches is paving the way for the comprehensive annotation of the human genome across diverse cell and tissue types exposed to various environmental conditions. This has already unmasked the positions of thousands of functional cis-regulatory elements integral to transcriptional regulation, such as enhancers, promoters, and anchors of chromatin interactions that populate the noncoding genome. Recent studies have shown that cis-regulatory elements are commonly the targets of genetic and epigenetic alterations associated with aberrant gene expression in cancer. Here, we review these findings to showcase the contribution of the noncoding genome and its alteration in the development and progression of cancer. We also highlight the opportunities to translate the biological characterization of genetic and epigenetic alterations in the noncoding cancer genome into novel approaches to treat or monitor disease.

SIGNIFICANCE

The majority of genetic and epigenetic alterations accumulate in the noncoding genome throughout oncogenesis. Discriminating driver from passenger events is a challenge that holds great promise to improve our understanding of the etiology of different cancer types. Advancing our understanding of the noncoding cancer genome may thus identify new therapeutic opportunities and accelerate our capacity to find improved biomarkers to monitor various stages of cancer development. Cancer Discov; 6(11); 1215-29. ©2016 AACR.

Three new pancreatic cancer susceptibility signals identified on chromosomes 1q32.1, 5p15.33 and 8q24.21

Genome-wide association studies (GWAS) have identified common pancreatic cancer susceptibility variants at 13 chromosomal loci in individuals of European descent. To identify new susceptibility variants, we performed imputation based on 1000 Genomes (1000G) Project data and association analysis using 5,107 case and 8,845 control subjects from 27 cohort and case-control studies that participated in the PanScan I-III GWAS. This analysis, in combination with a two-staged replication in an additional 6,076 case and 7,555 control subjects from the PANcreatic Disease ReseArch (PANDoRA) and Pancreatic Cancer Case-Control (PanC4) Consortia uncovered 3 new pancreatic cancer risk signals marked by single nucleotide polymorphisms (SNPs) rs2816938 at chromosome 1q32.1 (per allele odds ratio (OR) = 1.20, P = 4.88x10 -15), rs10094872 at 8q24.21 (OR = 1.15, P = 3.22x10 -9) and rs35226131 at 5p15.33 (OR = 0.71, P = 1.70x10 -8). These SNPs represent independent risk variants at previously identified pancreatic cancer risk loci on chr1q32.1 ( NR5A2), chr8q24.21 ( MYC) and chr5p15.33 ( CLPTM1L- TERT) as per analyses conditioned on previously reported susceptibility variants. We assessed expression of candidate genes at the three risk loci in histologically normal ( n = 10) and tumor ( n = 8) derived pancreatic tissue samples and observed a marked reduction of NR5A2 expression (chr1q32.1) in the tumors (fold change -7.6, P = 5.7x10 -8). This finding was validated in a second set of paired ( n = 20) histologically normal and tumor derived pancreatic tissue samples (average fold change for three NR5A2 isoforms -31.3 to -95.7, P = 7.5x10 -4-2.0x10 -3). Our study has identified new susceptibility variants independently conferring pancreatic cancer risk that merit functional follow-up to identify target genes and explain the underlying biology.

Association of three 8q24 polymorphisms with prostate cancer susceptibility: evidence from a meta-analysis with 50,854 subjects

The 8q24 polymorphisms have been implicated in various cancers. Three 8q24 polymorphisms (rs1447295 C>A, rs16901979 C>A, and rs6983267 T>G) have been extensively investigated for their association with prostate cancer (PCa) susceptibility, yet conclusions are contradictory. We conducted a comprehensive meta-analysis to reevaluate the associations between those polymorphisms and PCa susceptibility, according to the latest meta-analysis guidelines (PRISMA). Eligible publications were searched from MEDLINE, EMBASE and CBM. False positive report possibility analysis was performed. We totally collected 20184 cases and 20439 controls from 20 studies for the rs1447295 C>A, 1850 cases and 2090 controls from 7 studies for the rs16901979 C>A, and 12233 cases and 7582 controls from 17 studies for the rs6983267 T>G. Overall, each of studied 8q24 polymorphisms was significantly associated with PCa risk individually. Significant associations were also observed in stratified analysis by ethnicity, source of control, and quality score. Interestingly, the effect of rs1447295 on PCa risk was observed among Caucasians and Asians, but not Africa-Americans. The effect of rs16901979 was more prominent among Africa-Americans than Asians. Likewise, rs6983267 conferred a higher Pca risk among Caucasians than Asians. Collectively, these 8q24 variant(s) may modulate PCa risk in an ethnic-specific manner.

Genetic variation at 8q24, family history of cancer, and upper gastrointestinal cancers in a Chinese population

Genetic variation at 8q24 is associated with prostate, bladder, breast, colorectal, thyroid, lung, ovarian, UADT, liver and stomach cancers. However, a role for variation at 8q24 in familial clustering of upper gastrointestinal cancers has not been studied. In order to explore potential inherited susceptibility, we analyzed epidemiologic data from a population-based case-control study of upper gastrointestinal cancers from Taixing, China. The study population includes 204 liver, 206 stomach, and 218 esophageal cancer cases and 415 controls. Associations between 8q24 rs1447295, rs16901979, rs6983267 and these cancers were stratified by family history of cancer. Odds ratios and 95% confidence intervals were adjusted for potential confounders: age, sex, education, tobacco smoking, alcohol consumption, and BMI at interview. We also adjusted for hepatitis B and aflatoxin (liver cancer) and Helicobacter pylori (stomach cancer). In a dominant model, among those with a family history of cancer, rs1447295 was positively associated with liver cancer (OR(adj) 2.80; 95% CI 1.15-6.80). Heterogeneity was observed (P(heterogeneity) = 0.029) with rs6983267 and liver cancer, with positive association in the dominant model among those with a family history of cancer and positive association in the recessive model among those without a family history of cancer. When considered in a genetic risk score model, each additional 8q24 risk genotype increased the odds of liver cancer by two-fold among those with a family history of cancer (OR(adj) 2.00; 95% CI 1.15-3.47). These findings suggest that inherited susceptibility to liver cancer may exist in the Taixing population and that variation at 8q24 might be a genetic component of that inherited susceptibility.

Association of common variants on chromosome 8q24 with gastric cancer in Venezuelan patients

Gastric cancer remains one of the leading causes of death in the world, being Central and South America among the regions showing the highest incidence and mortality rates worldwide. Although several single nucleotide polymorphisms (SNPs) identified in the chromosomal region 8q24 by genome-wide association studies have been related with the risk of different kinds of cancers, their role in the susceptibility of gastric cancer in Latin American populations has not been evaluated yet. Hereby, we performed a case-control study to explore the associations between three SNPs at 8q24 and gastric cancer risk in Venezuelan patients. We analyzed rs1447295, rs4733616 and rs6983267 SNPs in 122 paraffin-embedded tumor samples from archival bank and 129 samples with chronic gastritis (obtained by upper endoscopy during the study) from the Central Hospital of Barquisimeto (Lara, Venezuela). Genotypes were determined by PCR-RFLP reactions designed in this study for efficient genotyping of formalin-fixed/paraffin-embedded tissues. No significant differences in genotype frequencies between case and control groups were found. However, carriers of the homozygous TT genotype of SNP rs4733616 had an increased risk of developing poorly differentiated gastric cancer according to the codominant (OR=3.59, P=0.035) and the recessive models (OR=4.32, P=0.014, best-fitting model of inheritance), adjusted by age and gender. Our study suggests that the SNP rs4733616 is associated with susceptibility to poorly differentiated gastric cancer in Venezuelans. Additional studies are needed to further interrogate the prognostic value of the rs4733616 marker in this high-risk population for gastric cancer.

Genetic variations in colorectal cancer risk and clinical outcome

Colorectal cancer (CRC) has an apparent hereditary component, as evidenced by the well-characterized genetic syndromes and family history associated with the increased risk of this disease. However, in a large fraction of CRC cases, no known genetic syndrome or family history can be identified, suggesting the presence of “missing heritability” in CRC etiology. The genome-wide association study (GWAS) platform has led to the identification of multiple replicable common genetic variants associated with CRC risk. These newly discovered genetic variations might account for a portion of the missing heritability. Here, we summarize the recent GWASs related to newly identified genetic variants associated with CRC risk and clinical outcome. The findings from these studies suggest that there is a lack of understanding of the mechanism of many single nucleotide polymorphisms (SNPs) that are associated with CRC. In addition, the utility of SNPs as prognostic markers of CRC in clinical settings remains to be further assessed. Finally, the currently validated SNPs explain only a small fraction of total heritability in complex-trait diseases like CRC. Thus, the “missing heritability” still needs to be explored further. Future epidemiological and functional investigations of these variants will add to our understanding of CRC pathogenesis, and may ultimately lead to individualized strategies for prevention and treatment of CRC.

Association of 8q24 rs13281615A > G polymorphism with breast cancer risk: evidence from 40,762 cases and 50,380 controls

The association between a single nucleotide polymorphism rs13281615A > G located in the 8q24 and breast cancer risk is still controversial and ambiguous. Hence, we performed a more convincing and precise estimation of the relationship between 8q24 and breast cancer by meta-analyzing the currently available evidence from literature. PubMed, Ovid, Medline, and Web of Science databases were searched. A total of 10 publications containing 11 studies including 40,762 cases and 50,380 controls were identified. Crude odds ratio with 95 % confidence interval was used to assess the strength of association. We observed that the 8q24 rs13281615A > G polymorphism was significantly correlated with breast cancer risk when all studies were pooled into the meta analysis. In the stratified analysis by ethnicity, significantly increased risks were also found among Caucasians for all genetic models. For mixed ethnicities, significantly increased risks were found for all genetic models except for the allele contrast model. However, no significantly increased risk was found among Africans for all genetic models. Interestingly, when stratified by BRCA1 mutation carriers status, significantly decreased breast cancer risk was found for allele contrast model. But significantly increased breast cancer risk was found in the BRCA2 mutation carriers for all genetic models except for the recessive model. There was no evidence for significant association between 8q24 rs13281615A > G polymorphism and breast cancer risk in BRCA1 and BRCA2 positive cohort in all comparable models. In conclusion, this meta-analysis suggests that the 8q24 rs13281615A > G polymorphism is a low-penetrant risk factor for developing breast cancer but may not be in Africans.

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.

Association between total number of deaths, diabetes mellitus, incident cancers, and haplotypes in chromosomal region 8q24 in a prospective study

The 8q24 region is a gene desert, although chromosomal aberrations and somatic amplification involving this region, including translocations involving the protooncogene c-MYC, have been frequently reported in people with cancer. To investigate the role of variants in 8q24 region, the authors analyzed data from a prospective study (n = 10,372 participants who were followed for 11 years) in which a large number of health events (>1,500) occurred (1993-1998). They genotyped all subjects for 5 candidate single nucleotide polymorphisms (rs672888, rs1447295, rs9642880, rs16901979, and rs6983267) that were identified in previous genome-wide scans. Although significant associations with individual single nucleotide polymorphisms were small in magnitude, the authors observed higher increases in the risks of different types of cancer with specific haplotypes, particularly when subjects were homozygous for the haplotype: for breast cancer and homozygotes for haplotype CAGCT, hazard ratio = 3.40, 95% confidence interval: 1.24, 9.21; for prostate cancer and grouped rare haplotypes, hazard ratio = 7.43, 95% confidence interval: 3.00, 18.37; and for brain cancer and homozygotes for haplotype CGGCT, hazard ratio = 13.48, 95% confidence interval: 3.00, 59.53. Significant associations were also observed between haplotypes and deaths from cardiovascular diseases and cerebrovascular diseases; the most stable association was between homozygotes for haplotypes CGTCG and CAGCT and total deaths in men (hazard ratio = 3.5, 95% confidence interval: 1.8, 6.9, and hazard ratio = 2.8, 95% confidence interval: 1.3, 6.4, respectively). In conclusion, the authors have observed a strong pleiotropic effect of the 8q24 region in a large prospective study. This observation can shed light on the mechanisms underlying reported associations between 8q24 variants and disparate chronic diseases.

Meta-analysis of 8q24 for seven cancers reveals a locus between NOV and ENPP2 associated with cancer development

Background

Human chromosomal region 8q24 contains several genes which could be functionally related to cancer, including the proto-oncogene c-MYC. However, the abundance of associations around 128 Mb on chromosome 8 could mask the appearance of a weaker, but important, association elsewhere on 8q24.

Methods

In this study, we completed a meta-analysis of results from nine genome-wide association studies for seven types of solid-tumor cancers (breast, prostate, pancreatic, lung, ovarian, colon, and glioma) to identify additional associations that were not apparent in any individual study.

Results

Fifteen SNPs in the 8q24 region had meta-analysis p-values < 1E-04. In particular, the region consisting of 120,576,000-120,627,000 bp contained 7 SNPs with p-values < 1.0E-4, including rs6993464 (p = 1.25E-07). This association lies in the region between two genes, NOV and ENPP2, which have been shown to play a role in tumor development and motility. An additional region consisting of 5 markers from 128,478,000 bp - 128,524,000 (around gene POU5F1B) had p-values < 1E-04, including rs6983267, which had the smallest p-value (p = 6.34E-08). This result replicates previous reports of association between rs6983267 and prostate and colon cancer.

Conclusions

Further research in this area is warranted as these results demonstrate that the chromosomal region 8q24 may contain a locus that influences general cancer susceptibility between 120,576 and 120,630 kb.

The multi-cancer marker, rs6983267, located at region 3 of chromosome 8q24, is associated with prostate cancer in Greek patients but does not contribute to the aggressiveness of the disease

BACKGROUND

Recently, several polymorphisms located on human chromosome 8q24 were found to be associated with prostate cancer risk with different frequency and incidence among the investigated populations. The authors conducted a prostate cancer case-control study in the Greek population to evaluate the association of the single nucleotide polymorphism (SNP) rs6983267, located at region 3 of chromosome 8q24, with this type of cancer.

METHODS

Samples of total blood from 86 patients with histologically confirmed prostate cancer and 99 healthy individuals were genotyped using real time polymerase chain reaction (PCR). Tumor-node-metastasis (TNM) stage, Gleason score and levels of prostate-specific antigen (PSA) at diagnosis were included in the analysis.

RESULTS

A highly significant association (odds ratio=2.84 and p-value=0.002) was found between rs6983267 and prostate cancer in the Greek population. The sensitivity, specificity, negative and positive predictive values of the presence of G allele for the discrimination between patients and controls were 81.40%, 39.4%, 53.9% and 70.9%, respectively. A lower proportion of homozygotes was found in patients with PSA level <4 ng/mL compared to those with PSA level more than 4 ng/mL (p=0.019). None of the other clinical factors nor the aggressiveness of the disease were found to be significantly associated with rs6983267 genotype.

CONCLUSIONS

The SNP rs6983267 is an established marker for a range of cancers. In prostate cancer, it indicates an enhanced risk for carriers to develop the disease in general. In our study it showed no association with aggressive forms or familial and early-onset prostate cancer families.

Prostate cancer risk alleles and their associations with other malignancies

OBJECTIVE

To determine whether certain risk alleles are responsible for the relationship between prostate cancer (CaP) and other malignancies. CaP has been associated with other common malignancies. Recently, numerous single nucleotide polymorphisms (SNPs) have been associated with CaP susceptibility.

METHODS

We genotyped 1121 patients with CaP for 36 risk alleles known to be significantly associated with CaP susceptibility and determined their relationships to other malignancies in CaP probands and their first-degree relatives.

RESULTS

The most common other malignancies in the CaP probands were nonmelanoma skin cancer (13.6%), leukemia (7.3%), melanoma (3.9%), non-Hodgkin's lymphoma (0.7%), colorectal cancer (0.6%), and multiple myeloma (0.3%). Among the probands, a significantly increased frequency of leukemia was found in the carriers of SNP rs2736098 (5p15, P = .03) and melanoma in the carriers of either SNP rs1512268 (8p21, P = .006) or SNP rs5759167 (22q13, P = .02). Multiple myeloma was more common in carriers of SNP rs9364554 (6q25, P = .02). The probands who were carriers of SNP rs16901979 (8q24) were significantly more likely to report a family history of melanoma (P = .03), and the probands with a family history of multiple myeloma and non-Hodgkin's disease were significantly more likely to be carriers of SNP rs12621278 (2q31, P = .04) and rs6465657 (7q21, P = .02), respectively.

CONCLUSION

Certain alleles associated with CaP susceptibility might be associated with an increased or a decreased risk of other malignancies in CaP probands and their first-degree relatives. Additional studies are warranted to examine the underlying mechanisms of these SNPs in CaP and other malignancies.

Green tea consumption, inflammation and the risk of primary hepatocellular carcinoma in a Chinese population

OBJECTIVE

Green tea has been found to possess anti-inflammatory, anti-oxidative and anti-carcinogenic properties. The present study examines the association between green tea drinking and hepatocellular carcinoma (HCC) and its interactions with other risk or protective factors and single nucleotide polymorphisms (SNP) of inflammation and oxidative stress related genes.

METHODS

A population-based case-control study with 204 primary HCC cases and 415 healthy controls was conducted in Taixing, China. Epidemiological data were collected using a standard questionnaire. SNPs of genes of the inflammation and metabolic pathways were genotyped at the UCLA Molecular Epidemiology Laboratory. Logistic regression was performed to estimate adjusted odds ratios and 95% confidence intervals.

RESULTS

Longer duration and larger quantities of green tea consumption were inversely associated with primary HCC. Individuals who drank green tea longer than 30 years were at lowest risk (adjusted OR=0.44, 95% CI: 0.19-0.96) compared with non-drinkers. A strong interaction was observed between green tea drinking and alcohol consumption (adjusted OR for interaction=3.40, 95% CI: 1.26-9.16). Green tea drinking was also observed to have a potential effect modification on HBV/HCV infection, smoking and polymorphisms of inflammation related cytokines, especially for IL-10.

CONCLUSION

Green tea consumption may protect against development of primary HCC. Potential effect modifications of green tea on associations between primary HCC and alcohol drinking, HBV/HCV infection, and inflammation-related SNPs were suggested.

Smoking and cervical cancer

Cervical cancer (CC) is the third most common cancer in women worldwide; however, CC is a preventable disease, and much effort should be done to prevent it. Persistence of high-risk HPV infection is the strongest epidemiologic risk factor for CC, however it is not sufficient for development of the disease it cofactors should be present. In 2004; IARC listed cervical cancer among those causally related to smoking. Smoking interferes with incidence and prevalence of HPV infection and is associated with cervical intraepithelial neoplasia and invasive CC. Multiple factors seem to intervene on cervical carcinogenesis related with tobacco, especially by direct local carcinogenic effect and local immunosuppression. Smoking addition is also closely related with other confounding factors, like unfavorable psychosocial events, systemic immunity, contraception, and nutrition, which got difficult epidemiologic evaluation of smoking role on cervical carcinogenesis. Smoking habits should be taken in account in clinical practice and in research concerning CC.

Possible association between a genetic polymorphism at 8q24 and risk of upper gastrointestinal cancer

Over recent years, genome-wide association studies have contributed to our understanding of genetic susceptibility to sporadic cancer. In this study, we assessed the association between upper gastrointestinal cancer risk and four genome-wide association studies-identified single nucleotide polymorphisms (SNPs), implicated earlier in prostate and colorectal cancer susceptibility. Genotyping for each SNP was performed in two independent Caucasian population-based case-control studies. The first study comprised 290 gastric cancer cases and 374 controls. The second study included 185 noncardia gastric cancers, 123 cardia cancers, 158 oesophageal cancers and 209 controls. Odds ratios (ORs) were computed from logistic models and adjusted for potential confounding variables. An inverse association was observed between the SNP rs1447295, located at 8q24, and gastric cancer risk in the first study population (OR=0.63; 95% confidence interval: 0.41-0.97). A positive association was observed for the same SNP and oesophageal squamous cell carcinoma in the second study population (OR=7.43; 95% confidence interval: 1.37-49.98). No significant associations were detected in either study for the three remaining SNPs (rs6983297, rs10505477 and rs719725). Our data represent novel findings on heritable susceptibility to gastric and oesophageal cancer and warrant validation in additional populations.

Genetic variation in the prostate stem cell antigen gene and upper gastrointestinal cancer in white individuals

BACKGROUND & AIMS

An association between gastric cancer and the rs2294008 (C>T) polymorphism in the prostate stem cell antigen (PSCA) gene has been reported for several Asian populations. We set out to determine whether such an association exists in white individuals.

METHODS

We genotyped 166 relatives of gastric cancer patients, including 43 Helicobacter pylori-infected subjects with hypochlorhydria and gastric atrophy, 65 infected subjects without these abnormalities, 58 H pylori-negative relatives, and 100 population controls. Additionally, a population-based study of chronic atrophic gastritis provided 533 cases and 1054 controls. We then genotyped 2 population-based, case-control studies of upper gastrointestinal cancer: the first included 312 gastric cancer cases and 383 controls; the second included 309 gastric cancer cases, 159 esophageal cancer cases, and 211 controls. Odds ratios were computed from logistic models and adjusted for confounding variables.

RESULTS

Carriage of the risk allele (T) of rs2294008 in PSCA was associated with chronic atrophic gastritis (adjusted odds ratio [OR], 1.5; 95% confidence interval [CI]: 1.1-1.9) and noncardia gastric cancer (OR, 1.9; 95% CI: 1.3-2.8). The association was strongest for the diffuse histologic type (OR, 3.2; 95% CI: 1.2-10.7). An inverse association was observed between carriage of the risk allele and gastric cardia cancer (OR, 0.5; 95% CI: 0.3-0.9), esophageal adenocarcinoma (OR, 0.5; 95% CI: 0.3-0.9), and esophageal squamous cell carcinoma (OR, 0.4; 95% CI: 0.2-0.9).

CONCLUSIONS

The rs2294008 polymorphism in PSCA increases the risk of noncardia gastric cancer and its precursors in white individuals but protects against proximal cancers.

Characterization of the association between 8q24 and colon cancer: gene-environment exploration and meta-analysis

BACKGROUND

Genome-wide association studies and subsequent replication studies have shown that single nucleotide polymorphisms (SNPs) in the chromosomal region 8q24 are associated with colorectal cancer susceptibility.

METHODS

We examined 11 SNP markers in the 8q24 region between 128.47 and 128.54 Mb, using a total of 1,987 colon cases and 2,339 controls who self-reported as white from two independent, well-characterized study populations. Analysis was performed separately within each study, and combined using random effects meta-analysis. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) and to test for effect modification by known colon cancer risk factors. We also performed a meta-analysis combining our results with previous studies.

RESULTS

We observed evidence of association for four SNPs in low to high linkage disequilibrium (r2 ranging from 0.18 to 0.93) localized in a 16.2 kb region defined by rs10505477 and rs1056368. The combined results for our two studies of colon cancer showed an OR of 1.10 (95% CI: 1.01-1.20, Ptrend = 0.023), and a meta-analysis of our results with previously reported studies of colon and colorectal cancer strongly support the association for this SNP (combined OR for rs6983267 = 1.21, 95% CI: 1.18-1.24, p = 5.5 × 10-44). We did not observe any notable evidence of effect modification by known colon cancer risk factors, and risk did not differ significantly by tumor site or stage.

CONCLUSIONS

Our study confirms the association between polymorphisms on chromosome 8q24 and colon cancer risk and suggests that the susceptibility locus in region 8q24 is not strongly modified by various lifestyle, environmental, and demographic risk factors for colon cancer.

8q24 sequence variants in relation to prostate cancer risk among men of African descent: a case-control study

BACKGROUND

Human chromosome 8q24 has been implicated in prostate tumorigenesis.

METHODS

Consequently, we evaluated seven 8q24 sequence variants relative to prostate cancer (PCA) in a case-control study involving men of African descent. Genetic alterations were detected in germ-line DNA from 195 incident PCA cases and 531 controls using TaqMan polymerase chain reaction (PCR).

RESULTS

Inheritance of the 8q24 rs16901979 T allele corresponded to a 2.5-fold increase in the risk of developing PCA for our test group. These findings were validated using multifactor dimensionality reduction (MDR) and permutation testing (p = 0.038). The remaining 8q24 targets were not significantly related to PCA outcomes.

CONCLUSIONS

Although compelling evidence suggests that the 8q24 rs16901979 locus may serve as an effective PCA predictor, our findings require additional evaluation in larger studies.

Risk of genome-wide association study-identified genetic variants for colorectal cancer in a Chinese population

BACKGROUND

Recent genome-wide association studies have identified 10 single nucleotide polymorphisms (SNP) associated with colorectal cancer (CRC) in Caucasians. This study evaluated the effects of these newly identified SNPs in a Chinese population.

METHODS

We assessed the associations of these 10 SNPs with CRC in a case-control study that consisted of 2,124 cases and 2,124 controls. Odds ratios (OR) and 95% confidence intervals were computed by logistic regression, and cumulative effect of risk genotypes were also calculated.

RESULTS

We found that only five SNPs (rs6983267, rs4939827, rs10795668, rs3802842, and rs961253) were significantly associated with risk of CRC in our study population in the same direction as reported by previous genome-wide association studies, with the ORs ranging from 1.11 to 2.96. A cumulative effect was observed with the ORs being gradually elevated with increasing number of risk genotypes (P(trend) = 1.32 x 10(-21)), and patients carrying > or = 4 risk genotypes had 3.25-fold increased CRC risk (95% confidence interval, 2.24-4.72) compared with patients carrying no risk genotype. Furthermore, we found that rs10795668 was associated with increased risk only in rectal cancer but not colon cancer, and rs3802842 was also significantly associated with advanced stages of CRC.

CONCLUSIONS

These results suggest that rs6983267, rs4939827, rs10795668, rs3802842, and rs961253 SNPs are associated with the risk of CRC in the Chinese population individually and jointly.

IMPACT

Our results provide new insights into colorectal tumorigenesis and have potential implications in early detection and target treatment of CRC in non-Western populations.

Associations between NBS1 polymorphisms, haplotypes and smoking-related cancers

Constituents of tobacco smoke can cause DNA double-strand breaks (DSBs), leading to tumorigenesis. The NBS1 gene product is a vital component in DSB detection and repair, thus genetic variations may influence cancer development. We examined the associations between NBS1 polymorphisms and haplotypes and newly incident smoking-related cancers in three case-control studies (Los Angeles: 611 lung and 601 upper aero-digestive tract (UADT) cancer cases and 1040 controls; Memorial Sloan-Kettering Cancer Center: 227 bladder cancer cases and 211 controls and Taixing, China: 218 esophagus, 206 stomach, 204 liver cancer cases and 415 controls). rs1061302 was associated with cancers of the lung [adjusted odds ratio (OR(adj)) = 1.6, 95% confidence interval (CI): 1.2, 2.4], larynx (OR(adj) = 0.56, 95% CI: 0.32, 0.97) and liver (OR(adj) = 1.7, 95% CI: 1.0, 2.9). Additionally, positive associations were found for rs709816 with bladder cancer (OR(adj) = 4.2, 95% CI: 1.4, 12) and rs1063054 with lung cancer (OR(adj) = 1.6, 95% CI: 1.0, 2.3). Some associations in lung and stomach cancers varied with smoking status. CAC haplotype was positively associated with smoking-related cancers: lung (OR(adj) = 1.7, 95% CI: 1.1, 2.9) and UADT (OR(adj) = 2.0, 95% CI: 1.1, 3.7), specifically, oropharynx (OR(adj) = 2.1, 95% CI: 1.0, 4.2) and larynx (OR(adj) = 4.8, 95% CI: 1.7, 14). Bayesian false-discovery probabilities were calculated to assess Type I error. It appears that NBS1 polymorphisms and haplotypes may be associated with smoking-related cancers and that these associations may differ by smoking status. Our findings also suggest that single-nucleotide polymorphisms located in the binding region of the MRE-RAD50-NBS1 complex or microRNA targeted pathways may influence tumor development. These hypotheses should be further examined in functional studies.

No effect of cancer-associated SNP rs6983267 in the 8q24 region on co-expression of MYC and TCF7L2 in normal colon tissue

A single nucleotide polymorphism (SNP) rs6983267, located within the 8q24 region, is strongly associated with risk of colorectal and prostate cancer. It has been suggested that the mechanism of this association is related to differential interaction of TCF7L2 protein (previously known as TCF-4) with alleles of rs6983267, influencing the expression of a well-known oncogene, MYC, located 335 Kb telomeric. Here, we tested the correlation between mRNA expression of MYC and several alternatively spliced forms of TCF7L2 in 117 non-cancer colon samples. We observed a strong correlation (r = 0.60, p < 10(-6)) between expression of MYC and a unique splicing form of TCF7L2. The level of MYC expression in these samples was associated with expression of some TCF7L2 splicing forms but not with genotypes of rs6983267, or interaction of rs6983267 with TCF7L2 expression. These findings suggest that some splicing forms of TCF7L2 may be functionally important for regulation of MYC expression in colon tissue but this regulation is not directly dependent on rs6983267.

Validating, augmenting and refining genome-wide association signals

Studies using genome-wide platforms have yielded an unprecedented number of promising signals of association between genomic variants and human traits. This Review addresses the steps required to validate, augment and refine such signals to identify underlying causal variants for well-defined phenotypes. These steps include: large-scale exact replication across both similar and diverse populations; fine mapping and resequencing; determination of the most informative markers and multiple independent informative loci; incorporation of functional information; and improved phenotype mapping of the implicated genetic effects. Even in cases for which replication proves that an effect exists, confident localization of the causal variant often remains elusive.

Dense genome-wide SNP linkage scan in 301 hereditary prostate cancer families identifies multiple regions with suggestive evidence for linkage

The search for susceptibility loci in hereditary prostate cancer (HPC) has proven challenging due to genetic and disease heterogeneity. Multiple risk loci have been identified to date, however few loci have been replicated across independent linkage studies. In addition, most previous analyses have been hampered by the relatively poor information content provided by microsatellite scans. To overcome these issues, we have performed linkage analyses on members of 301 HPC families genotyped using the Illumina SNP linkage panel IVb. The information content for this panel, averaged over all pedigrees and all chromosomes, was 86% (range 83-87% over chromosomes). Analyses were also stratified on families according to disease aggressiveness, age at diagnosis and number of affected individuals to achieve more genetically homogeneous subsets. Suggestive evidence for linkage was identified at 7q21 (HLOD = 1.87), 8q22 (KCLOD = 1.88) and 15q13-q14 (HLOD = 1.99) in 289 Caucasian families, and nominal evidence for linkage was identified at 2q24 (LOD = 1.73) in 12 African American families. Analysis of more aggressive prostate cancer phenotypes provided evidence for linkage to 11q25 (KCLOD = 2.02), 15q26 (HLOD = 1.99) and 17p12 (HLOD = 2.13). Subset analyses according to age at diagnosis and number of affected individuals also identified several regions with suggestive evidence for linkage, including a KCLOD of 2.82 at 15q13-q14 in 128 Caucasian families with younger ages at diagnosis. The results presented here provide further evidence for a prostate cancer susceptibility locus on chromosome 15q and demonstrate the power of utilizing high information content SNP scans in combination with homogenous collections of large prostate cancer pedigrees.