A replication study and genome-wide scan of single-nucleotide polymorphisms associated with pancreatic cancer risk and overall survival

Systematic analysis on expression quantitative trait loci identifies a novel regulatory variant in ring finger and WD repeat domain 3 associated with prognosis of pancreatic cancer

BACKGROUND

Pancreatic adenocarcinoma (PAAD) is an extremely lethal malignancy. Identification of the functional genes and genetic variants related to PAAD prognosis is important and challenging. Previously identified prognostic genes from several expression profile analyses were inconsistent. The regulatory genetic variants that affect PAAD prognosis were largely unknown.

METHODS

Firstly, a meta-analysis was performed with seven published datasets to systematically explore the candidate prognostic genes for PAAD. Next, to identify the regulatory variants for those candidate genes, expression quantitative trait loci analysis was implemented with PAAD data resources from The Cancer Genome Atlas. Then, a two-stage association study in a total of 893 PAAD patients was conducted to interrogate the regulatory variants and find the prognostic locus. Finally, a series of biochemical experiments and phenotype assays were carried out to demonstrate the biological function of variation and genes in PAAD progression process.

RESULTS

A total of 128 genes were identified associated with the PAAD prognosis in the meta-analysis. Fourteen regulatory loci in 12 of the 128 genes were discovered, among which, only rs4887783, the functional variant in the promoter of Ring Finger and WD Repeat Domain 3 ( RFWD3 ), presented significant association with PAAD prognosis in both stages of the population study. Dual-luciferase reporter and electrophoretic mobility shift assays demonstrated that rs4887783-G allele, which predicts the worse prognosis, enhanced the binding of transcript factor REST, thus elevating RFWD3 expression. Further phenotypic assays revealed that excess expression of RFWD3 promoted tumor cell migration without affecting their proliferation rate. RFWD3 was highly expressed in PAAD and might orchestrate the genes in the DNA repair process.

CONCLUSIONS

RFWD3 and its regulatory variant are novel genetic factors for PAAD prognosis.

Repeat expression is linked to patient survival and exhibits single nucleotide variation in pancreatic cancer revealing LTR70:r.879A>G

Despite an overwhelming number of cancer literature reporting the links between patient survival and the expression levels of genes or mutations/single nucleotide variations (SNVs) on them, there is only limited information on repeat elements, which make at least half the human genome. Here, we analysed RNA-seq data obtained from primary pancreatic cancer tissues of 51 patients and revealed that two transposons, HERVI-int and X6A_LINE, showed an upregulation trend in the patients who lived shorter, along with 56 other potential repeats which were linked to survival. We also detected expressed single nucleotide variations (SNVs) on repeats, among which LTR70:r.879A>G stands out with the effect of its presence on this particular repeat's expression levels and a significant link to overall patient survival. Interestingly, the expression of LTR70:r.879A>G correlated with different cancer genes in comparison to its reference version highlighting the involvement of BRAF and Fumerate Hydratase with this expressed SNV. This is one of the first studies revealing possible links between repeat expression and survival in cancer and it warrants further research in this avenue.

Susceptibility loci for pancreatic cancer in the Brazilian population

BACKGROUND

Pancreatic adenocarcinoma (PA) is a very aggressive cancer and has one of the poorest prognoses. Usually, the diagnosis is late and resistant to conventional treatment. Environmental and genetic factors contribute to the etiology, such as tobacco and alcohol consumption, chronic pancreatitis, diabetes and obesity. Somatic mutation in pancreatic cancer cells are known and SNP profile by GWAS could access novel genetic risk factors for this disease in different population context. Here we describe a SNP panel for Brazilian pancreatic cancer, together with clinical and epidemiological data.

METHODS

78 pancreatic adenocarcinoma and 256 non-pancreatic cancer subjects had 25 SNPs genotyped by real-time PCR. Unconditional logistic regression methods were used to assess the main effects on PA risk, using allelic, co-dominant and dominant inheritance models.

RESULTS

9 SNPs were nominally associated with pancreatic adenocarcinoma risk, with 5 of the minor alleles conferring protective effect while 4 related as risk factor. In epidemiological and clinical data, tobacco smoking, diabetes and pancreatitis history were significantly related to pancreatic adenocarcinoma risk. Polygenic risk scores computed using the SNPs in the study showed strong associations with PA risk.

CONCLUSION

We could assess for the first time some SNPs related with PA in Brazilian populations, a result that could be used for genetic screening in risk population such as familial pancreatic cancer, smokers, alcohol users and diabetes patients.

Lack of association of CD44-rs353630 and CHI3L2-rs684559 with pancreatic ductal adenocarcinoma survival

Although pancreatic ductal adenocarcinoma (PDAC) survival is poor, there are differences in patients' response to the treatments. Detection of predictive biomarkers explaining these differences is of the utmost importance. In a recent study two genetic markers (CD44-rs353630 and CHI3L2-rs684559) were reported to be associated with survival after PDAC resection. We attempted to replicate the associations in 1856 PDAC patients (685 resected with stage I/II) from the PANcreatic Disease ReseArch (PANDoRA) consortium. We also analysed the combined effect of the two genotypes in order to compare our results with what was previously reported. Additional stratified analyses considering TNM stage of the disease and whether the patients received surgery were also performed. We observed no statistically significant associations, except for the heterozygous carriers of CD44-rs353630, who were associated with worse OS (HR = 5.01; 95% CI 1.58-15.88; p = 0.006) among patients with stage I disease. This association is in the opposite direction of those reported previously, suggesting that data obtained in such small subgroups are hardly replicable and should be considered cautiously. The two polymorphisms combined did not show any statistically significant association. Our results suggest that the effect of CD44-rs353630 and CHI3L2-rs684559 cannot be generalized to all PDAC patients.

Validation of genome-wide association study-identified single nucleotide polymorphisms in a case-control study of pancreatic cancer from Taiwan

Background

Due to differences in genetic background, it is unclear whether the genetic loci identified by the previous genome-wide association studies (GWAS) of pancreatic cancer also play significant roles in the development of pancreatic cancer among the Taiwanese population.

Methods

This study aimed to validate the 25 pancreatic cancer GWAS-identified single nucleotide polymorphisms (SNPs) in a case-control study (278 cases and 658 controls) of pancreatic cancer conducted in Taiwan. Statistical analyses were conducted to determine the associations between the GWAS-identified SNPs and pancreatic cancer risk. Gene-environment interaction analysis was conducted to evaluate the interactions between SNPs and environmental factors on pancreatic cancer risk.

Results

Among the 25 GWAS-identified SNPs, 7 (rs2816938 (~ 11 kb upstream of NR5A2), rs10094872 (~ 28 kb upstream of MYC), rs9581943 (200 bp upstream of PDX1) and 4 chromosome 13q22.1 SNPs: rs4885093, rs9573163, rs9543325, rs9573166) showed a statistically significant association with pancreatic cancer risk in the current study. Additional analyses showed two significant gene-environment interactions (between poor oral hygiene and NR5A2 rs2816938 and between obesity and PDX1 rs9581943) on the risk of pancreatic cancer.

Conclusions

The current study confirmed the associations between 7 of the 25 GWAS-identified SNPs and pancreatic risk among the Taiwanese population.

Furthermore, pancreatic cancer was jointly influenced by lifestyle and medical factors, genetic polymorphisms, and gene-environment interaction. Additional GWAS is needed to determine the genetic polymorphisms that are more relevant to the pancreatic cancer cases occurring in Taiwan.

Updated risk factors to inform early pancreatic cancer screening and identify high risk patients

Pancreatic adenocarcinoma (PDAC) is associated with poor clinical outcomes and incomplete responses to conventional therapy. Therefore, there is an unmet clinical need to better understand the predisposing factors for pancreatic cancer in hopes of providing early screening to high-risk patients. While select risk factors such as age, race, and family history, or predisposing syndromes are unavoidable, there are several new and established risk factors that allow for intervention, namely by counseling patients to make the appropriate lifestyle modifications. Here, we discuss the best-studied risk factors for PDAC such as tobacco use and chronic pancreatitis, as well as newly emerging risk factors including select nutritional deficits, bacterial infections, and psychosocial factors. As several of these risk factors appear to be additive or synergistic, by understanding their relationships and offering coordinated, multidisciplinary care to high-risk patients, it may be possible to reduce pancreatic cancer incidence and improve clinical outcomes through early detection.

Genetic variability of the ABCC2 gene and clinical outcomes in pancreatic cancer patients

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis, caused by various factors, such as the aggressiveness of the disease, the limited therapeutic options and the lack of early detection and risk markers. The ATP binding cassette subfamily C member 2 (ABCC2) protein plays a critical role in response to various drugs and is differentially expressed in gemcitabine sensitive and resistant cells. Moreover, single nucleotide polymorphisms (SNPs) in the gene have been associated with differential outcomes and prognosis in several tumour types. The aim of this study was to investigate the possible association between SNPs in the ABCC2 gene and overall survival (OS) in PDAC patients. We analysed 12 polymorphisms, including tagging-SNPs covering all the genetic variability of the ABCC2 gene and genotyped them in 1415 PDAC patients collected within the Pancreatic Disease ReseArch (PANDoRA) consortium. We tested the association between ABCC2 SNPs and PDAC OS using Cox proportional hazard models. We analysed PDAC patients dividing them by stage and observed that the minor alleles of three SNPs showed an association with worse OS [rs3740067: hazard ratio (HR) = 3.29, 95% confidence interval (CI) = 1.56-6.97, P = 0.002; rs3740073: HR = 3.11, 95% CI = 1.52-6.38, P = 0.002 and rs717620: HR = 2.90, 95% CI = 1.41-5.95, P = 0.004, respectively] in stage I patients. In patients with more advanced PDAC, we did not observe any statistically significant association. Our results suggest that rs3740067, rs3740073 and rs717620 could be promising prognostic markers in stage I PDAC patients.

Association of ABO polymorphisms and pancreatic Cancer/ Cardiocerebrovascular disease: a meta-analysis

Background

ABO gene polymorphisms have been reported to be associated with the risk of multiple cancers and cardiocerebrovascular diseases. However, the results remained controversial. In this study, we conducted a systematic review and meta-analysis to clarify the association between two SNPs (rs505922 and rs657152) in ABO gene and cancers/cardiocerebrovascular diseases.

Method

All eligible case-control studies come from PubMed, Embase and Web of Science up to Jan. 1, 2019. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the corresponding associations. Sensitivity analysis, publication bias assessment, and heterogeneity test were performed using STATA 12.0.

Results

A total of nineteen articles involving twenty-two case-control populations were included according to inclusion and exclusion criteria. Twelve populations (20,820 cases and 27,837 controls) were used to evaluate the relationship between rs505922 and overall cancers and nine populations (22,275 cases and 71,549 controls) were included to assess the association between rs505922 and cardiocerebrovascular diseases. The results showed a significant association between the rs505922 polymorphism and cancers (CvsT: OR = 1.13, 95%CI = 1.05–1.22, P = 0.001), and cardiocerebrovascular diseases (OR = 1.36, 95%CI = 1.19–1.57, P < 0.001). Five populations (8660 cases and 10,618 controls) were included to evaluate association between rs657152 and cancers and five populations (8105 cases and 6712 controls) were included to estimate the relationship between rs657152 and cardiocerebrovascular diseases. The result of meta-analysis reveals that rs657152 was significantly associated with cancers (OR = 1.18, 95%CI = 1.13–1.23, P < 0.001) and cardiocerebrovascular diseases (OR = 1.54, 95%CI = 1.24–1.92, P < 0.001).

Conclusion

Our study suggested that ABO polymorphisms might serve as a risk factor of pancreatic cancers and cardiocerebrovascular diseases.

Identification and Validation of a Biomarker Signature in Patients With Resectable Pancreatic Cancer via Genome-Wide Screening for Functional Genetic Variants

Importance

Surgery currently offers the only chance for a cure in pancreatic ductal adenocarcinoma (PDAC), but it carries a significant morbidity and mortality risk and results in varying oncologic outcomes. At present, to our knowledge, there are no tests available before surgical resection to identify tumors with an aggressive biological phenotype that could guide personalized treatment strategies.

Objective

Identification of noninvasive genetic biomarkers that could direct therapy in patients whose cases are amenable to pancreatic cancer resection.

Design, Setting, and Participants

This multicenter study combined a prospective European cohort of patients with PDAC who underwent pancreatic resection (from University Hospital of Zurich, Zurich, Switzerland; Cantonal Hospital of Winterthur, Winterthur, Switzerland; and University Clinic of Ulm, Ulm, Germany) with data from the Cancer Genome Atlas database in the United States, which includes prospectively registered patients with PDAC. A genome-wide screening for functional single-nucleotide polymorphisms (SNPs) that affect PDAC survival was conducted using the European cohort for identification and the Cancer Genome Atlas cohort for validation. We used Cox proportional hazards models to screen for high-frequency polymorphic variants that are associated with allelic differences in tumor-associated survival and either result in an altered protein structure and function or reside in known regulatory noncoding genomic regions. The false-discovery rate method was applied for multiple hypothesis-testing corrections. Data analysis occurred from November 2017 to May 2018.

Exposures

Pancreatic resection.

Main Outcomes and Measures

Tumor-associated survival.

Results

A total of 195 patients in the European cohort were included, as well as 136 patients in the Cancer Genome Atlas cohort (overall median [range] age, 66 [19-87] years; 156 [47.1%] were women, and 175 [52.9%] were men). Two SNPs in noncoding, functional regions of genes that regulate cancer progression, invasion, and metastasis were identified (CHI3L2 SNP rs684559 and CD44 SNP rs353630). These were associated with survival after PDAC resection; patients who carry the risk alleles at 1 of both SNP loci had a 2.63-fold increased risk for tumor-associated death compared with those with protective genotypes (hazard ratio for survival, 0.38 [95% CI, 0.27-0.53]; P = 1.0 × 10-8).

Conclusions and Relevance

The identified polymorphisms may serve as a noninvasive biomarker signature of prospective survival after pancreatic resection that is readily available at the time of PDAC diagnosis. This signature can be used to identify a subset of high-risk patients with PDAC with very low survival probability who might be eligible for inclusion in clinical trials of new therapeutic strategies, including neoadjuvant chemotherapy protocols. In addition, the biological knowledge about these SNPs could help guide the development of individualized genomic strategies for PDAC therapies.

A genetic variant in PIK3R1 is associated with pancreatic cancer survival in the Chinese population

Pancreatic cancer is one of the deadliest malignancies with few early detection tests or effective therapies. PI3K-AKT signaling is recognized to modulate cancer progression. We previously identified that a genetic variant in PKN1 increased pancreatic cancer risk through the PKN1/FAK/PI3K/AKT pathway. In order to investigate the associations between genetic variations in that pathway and pancreatic cancer prognosis, we conducted a two-stage survival analysis in a total of 547 Chinese pancreatic cancer patients. Consequently, a variant, rs13167294 A>C in PIK3R1, was significantly associated with poor survival in both stages and with hazard ratio being 1.32 (95% CI = 1.13-1.56, P = 0.0007) in the combined analysis. Function annotation and prediction suggested that genetic variants in this locus might affect overall survival of pancreatic cancer patients by regulating PIK3R1 expression.

Genetic determinants of telomere length and risk of pancreatic cancer: A PANDoRA study

Telomere deregulation is a hallmark of cancer. Telomere length measured in lymphocytes (LTL) has been shown to be a risk marker for several cancers. For pancreatic ductal adenocarcinoma (PDAC) consensus is lacking whether risk is associated with long or short telomeres. Mendelian randomization approaches have shown that a score built from SNPs associated with LTL could be used as a robust risk marker. We explored this approach in a large scale study within the PANcreatic Disease ReseArch (PANDoRA) consortium. We analyzed 10 SNPs (ZNF676-rs409627, TERT-rs2736100, CTC1-rs3027234, DHX35-rs6028466, PXK-rs6772228, NAF1-rs7675998, ZNF208-rs8105767, OBFC1-rs9420907, ACYP2-rs11125529 and TERC-rs10936599) alone and combined in a LTL genetic score ("teloscore", which explains 2.2% of the telomere variability) in relation to PDAC risk in 2,374 cases and 4,326 controls. We identified several associations with PDAC risk, among which the strongest were with the TERT-rs2736100 SNP (OR = 1.54; 95%CI 1.35-1.76; p = 1.54 × 10-10 ) and a novel one with the NAF1-rs7675998 SNP (OR = 0.80; 95%CI 0.73-0.88; p = 1.87 × 10-6 , ptrend = 3.27 × 10-7 ). The association of short LTL, measured by the teloscore, with PDAC risk reached genome-wide significance (p = 2.98 × 10-9 for highest vs. lowest quintile; p = 1.82 × 10-10 as a continuous variable). In conclusion, we present a novel genome-wide candidate SNP for PDAC risk (TERT-rs2736100), a completely new signal (NAF1-rs7675998) approaching genome-wide significance and we report a strong association between the teloscore and risk of pancreatic cancer, suggesting that telomeres are a potential risk factor for pancreatic cancer.

Closing the Disparity in Pancreatic Cancer Outcomes: A Closer Look at Nonmodifiable Factors and Their Potential Use in Treatment

OBJECTIVES

African Americans (AAs) have disproportionately higher incidence and lower survival rates from pancreatic cancer compared with whites. Historically, this disparity has been attributed to modifiable risk factors. Recent studies suggest that nonmodifiable aspects may also play an important role. We review these new contributions as potential targets for closing the disparity.

METHODS

A PubMed search was conducted to review studies of nonmodifiable elements contributing to pancreatic cancer disparities in AAs.

RESULTS

Several nonmodifiable risks are associated with the racial disparity in pancreatic cancer. SSTR5 P335L, Kaiso, and KDM4/JMJD2A demonstrate differential racial expression, increasing their potential as therapeutic targets. Many social determinants of health and their associations with diabetes, obesity, and the microbiome are partially modifiable risk factors that significantly contribute to outcomes in minorities. Barriers to progress include the low minority inclusion in research studies.

CONCLUSIONS

Genomics, epigenetics, the microbiome, and social determinants of health are components that contribute to the pancreatic cancer disparity in AAs. These factors can be researched, targeted, and modified to improve mortality rates. Closing the disparity in pancreatic cancer will require an integrated approach of personalized medicine, increased minority recruitment to studies, and advanced health care/education access.

Genome-wide Scan Identifies Role for AOX1 in Prostate Cancer Survival

BACKGROUND

Most men diagnosed with prostate cancer have low-risk cancers. How to predict prostate cancer progression at the time of diagnosis remains challenging.

OBJECTIVE

To identify single nucleotide polymorphisms (SNPs) associated with death from prostate cancer.

DESIGN, SETTING, AND PARTICIPANTS

Blood samples from 11 506 men in Sweden were collected during 1991-1996. Of these, 1053 men were diagnosed with prostate cancer and 245 died from the disease. Stage and grade at diagnosis and outcome information were obtained, and DNA from all cases was genotyped.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

A total of 6 126 633 SNPs were tested for association with prostate-cancer-specific survival time using a Cox proportional hazard model, adjusted for age, stage, and grade at diagnosis. A value of 1×10-6 was used as suggestive significance threshold. Positive candidate SNPs were tested for association with gene expression using expression quantitative trait locus analysis.

RESULTS AND LIMITATIONS

We found 12 SNPs at seven independent loci associated with prostate-cancer-specific survival time. One of 6 126 633 SNPs tested reached genome-wide significance (p<5×10-8) and replicated in an independent cohort: rs73055188 (p=5.27×10-9, per-allele hazard ratio [HR]=2.27, 95% confidence interval [CI] 1.72-2.98) in the AOX1 gene. A second SNP reached a suggestive level of significance (p<1×10-6) and replicated in an independent cohort: rs2702185 (p=7.1×10-7, per-allele HR=2.55, 95% CI=1.76-3.69) in the SMG7 gene. The SNP rs73055188 is correlated with AOX1 expression levels, which is associated with biochemical recurrence of prostate cancer in independent cohorts. This association is yet to be validated in other ethnic groups.

CONCLUSIONS

The SNP rs73055188 at the AOX1 locus is associated with prostate-cancer-specific survival time, and AOX1 gene expression level is correlated with biochemical recurrence of prostate cancer.

PATIENT SUMMARY

We identify two genetic markers that are associated with prostate-cancer-specific survival time.

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.

CLPTM1L gene rs402710 (C > T) and rs401681 (C > T) polymorphisms associate with decreased cancer risk: a meta-analysis

Cleft lip and palate transmembrane 1-like (CLPTM1L) gene rs402710 (C > T) and rs401681 (C > T) polymorphisms have been widely studied for their potential relation to cancer risk, but studies have produced conflicting results. To systematically evaluate the association between these two polymorphisms and overall cancer risk, we conducted a comprehensive meta-analysis on all relevant articles found in the PubMed and EMBASE databases published prior to May 1, 2017. There were 26 articles with 28 studies, including 30,770 cases and 34,089 controls, for the rs402710 polymorphism and 38 articles with 48 studies, including 67,849 cases and 328,226 controls, for the rs401681 polymorphism. The pooled results indicated that both rs402710 and rs401681 polymorphisms are significantly associated with decreased overall cancer risk. In our stratification analysis, a significant association of the rs402710 polymorphism with lung and bladder cancers was identified among Asian and Caucasian populations in both hospital-based and population-based studies. The rs401681 polymorphism was significantly associated with a decreased risk of lung cancer, bladder cancer, and basal cell carcinoma in Asians and in hospital-based studies. CLPTM1L gene rs402710 and rs401681 polymorphisms thus have a protective association with various types of cancer, especially lung cancer among Asians.

Racial Disparity in Gastrointestinal Cancer Risk

Cancer from the gastrointestinal tract and its associated excretory organs will occur in more than 300,000 Americans in 2017, with colorectal cancer responsible for >40% of that burden; there will be more than 150,000 deaths from this group of cancers in the same time period. Disparities among subgroups related to the incidence and mortality of these cancers exist. The epidemiology and risk factors associated with each cancer bear out differences for racial groups in the United States. Esophageal adenocarcinoma is more frequent in non-Hispanic whites, whereas esophageal squamous cell carcinoma with risk factors of tobacco and alcohol is more frequent among blacks. Liver cancer has been most frequent among Asian/Pacific Islanders, chiefly due to hepatitis B vertical transmission, but other racial groups show increasing rates due to hepatitis C and emergence of cirrhosis from non-alcoholic fatty liver disease. Gastric cancer incidence remains highest among Asian/Pacific Islanders likely due to gene-environment interaction. In addition to esophageal squamous cell carcinoma, cancers of the small bowel, pancreas, and colorectum show the highest rates among blacks, where the explanations for the disparity are not as obvious and are likely multifactorial, including socioeconomic and health care access, treatment, and prevention (vaccination and screening) differences, dietary and composition of the gut microbiome, as well as biologic and genetic influences. Cognizance of these disparities in gastrointestinal cancer risk, as well as approaches that apply precision medicine methods to populations with the increased risk, may reduce the observed disparities for digestive cancers.

Genetic polymorphisms associated with pancreatic cancer survival: a genome-wide association study

Previous findings on the association of genetic factors and pancreatic cancer survival are limited and inconsistent. In a two-stage study, we analyzed the existing genome-wide association study dataset of 868 pancreatic cancer patients from MD Anderson Cancer Center in relation to overall survival using Cox regression. Top hits were selected for replication in another 820 patients from the same institution using the Taqman genotyping method. Functional annotation, pathway analysis and gene expression analysis were conducted using existing software and databases. We discovered genome-wide significant associations of patient survival with three imputed SNPs which, in complete LD (r²  = 1), were intronic SNPs of the PAIP2B (rs113988120) and DYSF genes (rs112493246 and rs138529893) located on Chromosome 2. The variant alleles were associated with a 3.06-fold higher risk of death [95% confidence interval (CI) = 2.10-4.47, p=6.4 × 10-9] after adjusting for clinical factors. Eleven SNPs were tested in the replication study and the association of rs113988120 with survival was confirmed (hazard ratio: 1.57, 95% CI: 1.13-2.20,  p=0.008). In silico analysis found rs1139988120 might lead to altered motif. This locus is in LD (D' = 0.77) with three eQTL SNPs near or belong to the NAGK and MCEE genes. According to The Cancer Genome Atlas data and our previous RNA-sequencing data, the mRNA expression level of PAIP2B but not NAGK, MCEE or DYSF was significantly lower in pancreatic tumors than in normal adjacent tissues. Additional validation efforts and functional studies are warranted to demonstrate whether PAIP2B is a novel tumor suppressor gene and a potential therapeutic target for pancreatic cancer.

Association of genetic polymorphisms with survival of pancreatic ductal adenocarcinoma patients

Germline genetic variability might contribute, at least partially, to the survival of pancreatic ductal adenocarcinoma (PDAC) patients. Two recently performed genome-wide association studies (GWAS) on PDAC overall survival (OS) suggested (P < 10(-5)) the association between 30 genomic regions and PDAC OS. With the aim to highlight the true associations within these regions, we analyzed 44 single-nucleotide polymorphisms (SNPs) in the 30 candidate regions in 1722 PDAC patients within the PANcreatic Disease ReseArch (PANDoRA) consortium. We observed statistically significant associations for five of the selected regions. One association in the CTNNA2 gene on chromosome 2p12 [rs1567532, hazard ratio (HR) = 1.75, 95% confidence interval (CI) 1.19-2.58, P = 0.005 for homozygotes for the minor allele] and one in the last intron of the RUNX2 gene on chromosome 6p21 (rs12209785, HR = 0.88, 95% CI 0.80-0.98, P = 0.014 for heterozygotes) are of particular relevance. These loci do not coincide with those that showed the strongest associations in the previous GWAS. In silico analysis strongly suggested a possible mechanistic link between these two SNPs and pancreatic cancer survival. Functional studies are warranted to confirm the link between these genes (or other genes mapping in those regions) and PDAC prognosis in order to understand whether these variants may have the potential to impact treatment decisions and design of clinical trials.

Epidemiology and Inherited Predisposition for Sporadic Pancreatic Adenocarcinoma

Given the changing demographics of Western populations, the numbers of pancreatic cancer cases are projected to increase during the next decade. Diabetes, recent cigarette smoking, and excess body weight are the cancer's most consistent risk factors. The search for common and rare germline variants that influence risk of pancreatic cancer through genome-wide association studies and high-throughput-sequencing-based studies is underway and holds the promise of increasing the knowledge of variants and genes that play a role in inherited susceptibility of this disease. Research reported in this review has advanced the understanding of pancreatic cancer.

The role of the histoblood ABO group in cancer

Since the first link between blood type and cancer was described in 1953, numerous studies have sought to determine whether the histoblood ABO group is associated with tumorigenesis. In 2009, the first significant association between a SNP located within the ABO glycosyltransferase gene and increased risk of pancreatic cancer was reported. Here, we describe the history and possible functions of the histoblood ABO group and then provide evidence for a role of blood group antigens in the most common cancer types worldwide using both blood type and SNP data. We also explore whether confusion regarding the role of blood type in cancer risk may be attributable to heterogeneity within tumor types.

Lay abstract: ABO encodes the protein responsible for defining blood groups as A, B, AB or O. Despite over a century of investigation, it is not well known whether the blood group antigens have a function or if they contribute to human health. Over the last 60 years, associations between blood type and cancer risk have been reported, although the data have often been conflicting. To better understand the possible role of the ABO blood group in tumorigenesis, we review the data for the most common tumor types worldwide.

Pancreatic Cancer Genetics

Although relatively rare, pancreatic tumors are highly lethal [1]. In the United States, an estimated 48,960 individuals will be diagnosed with pancreatic cancer and 40,560 will die from this disease in 2015 [1]. Globally, 337,872 new pancreatic cancer cases and 330,391 deaths were estimated in 2012 [2]. In contrast to most other cancers, mortality rates for pancreatic cancer are not improving; in the US, it is predicted to become the second leading cause of cancer related deaths by 2030 [3, 4]. The vast majority of tumors arise in the exocrine pancreas, with pancreatic ductal adenocarcinoma (PDAC) accounting for approximately 95% of tumors. Tumors arising in the endocrine pancreas (pancreatic neuroendocrine tumors) represent less than 5% of all pancreatic tumors [5]. Smoking, type 2 diabetes mellitus (T2D), obesity and pancreatitis are the most consistent epidemiological risk factors for pancreatic cancer [5]. Family history is also a risk factor for developing pancreatic cancer with odds ratios (OR) ranging from 1.7-2.3 for first-degree relatives in most studies, indicating that shared genetic factors may play a role in the etiology of this disease [6-9]. This review summarizes the current knowledge of germline pancreatic cancer risk variants with a special emphasis on common susceptibility alleles identified through Genome Wide Association Studies (GWAS).

Genome-wide association study-identified SNPs (rs3790844, rs3790843) in the NR5A2 gene and risk of pancreatic cancer in Japanese

We genotyped 2 SNPs (rs3790844 T/C and rs3790843 G/A) in the NR5A2 gene that were identified in a genome-wide association study (GWAS) of pancreatic cancer in populations of mainly European ancestry, and we examined their associations with pancreatic cancer risk in a case-control study of 360 patients and 400 control subjects in Japan. Unconditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). The SNPs were in linkage disequilibrium (r² = 0.80). For rs3790843, the multivariable-adjusted OR was 0.75 (95% CI: 0.41–1.36) and 0.60 (95%CI: 0.33–1.08) for subjects with the AG and AA genotype, respectively, compared to subjects with the GG genotype. The per allele OR was 0.78 (0.62–0.99) (P = 0.046). For rs3790844, the multivariable-adjusted OR was 0.65 (95% CI: 0.37–1.14) and 0.47 (95%CI: 0.27–0.83) for subjects with the CT and CC genotype, respectively, compared to subjects with the TT genotype. The per allele OR was 0.70 (0.56–0.89) (P = 0.003). Our case-control study found that rs3790843 and rs3790844 in the NR5A2 gene are associated with pancreatic cancer risk in Japanese subjects. The direction of association is consistent with the prior findings from GWASs.

Validation and genomic interrogation of the MET variant rs11762213 as a predictor of adverse outcomes in clear cell renal cell carcinoma

BACKGROUND

The exonic single-nucleotide variant rs11762213 located in the MET oncogene has recently been identified as a prognostic marker in clear cell renal cell carcinoma (ccRCC). This finding was validated with The Cancer Genome Atlas (TCGA) cohort, and the biologic implications were explored.

METHODS

The genotype status for rs11762213 was available for 272 patients. Paired tumor-normal data, genomic data, and clinical information were acquired from ccRCC TCGA data sets. Cancer-specific survival (CSS) was analyzed with the competing risk method, and Cox proportional hazards regression was used for the analysis of the time to recurrence (TTR). Multivariate competing risk models were fitted to adjust for the validated Mayo Clinic Stage, Size, Grade, and Necrosis (SSIGN) score.

RESULTS

The variant allele of rs11762213 was detected in 10.3% of the cohort. After adjustments for the SSIGN score, the risk allele remained a significant predictor for adverse CSS (hazard ratio [HR], 3.88; 95% confidence interval [CI], 1.99-7.56; P < .0001) and for TTR (OR, 2.97; 95% CI, 1.43-6.2; P = .003). The mapping of rs11762213 to regulatory regions within the genome suggested that it might affect a DNA enhancer region. RNA and protein sequencing data for MET did not reveal differences in steady-state expression with stratification by risk allele.

CONCLUSIONS

The exonic MET variant rs11762213 is an independent predictor of adverse CSS and TTR in ccRCC and should be integrated into clinical practice for prognostic stratification. Genomic analysis suggests that the single-nucleotide polymorphism may affect an enhancer region located in the coding region of MET. Further biological mechanistic interrogation is currently underway.

Hereditary Pancreatic Cancer Syndromes

Despite decades of scientific and clinical research, pancreatic ductal adenocarcinoma (PDAC) remains a lethal malignancy. The clinical and pathologic features of PDAC, specifically the known environmental and genetic risk factors, are reviewed here with special emphasis on the hereditary pancreatic cancer (HPC) syndromes. For these latter conditions, strategies are described for their identification, for primary and secondary prevention in unaffected carriers, and for disease management in affected carriers. Nascent steps have been made toward personalized medicine based on the rational use of screening, tumor subtyping, and targeted therapies; these have been guided by growing knowledge of HPC syndromes in PDAC.

An analysis of the association between prostate cancer risk loci, PSA levels, disease aggressiveness and disease-specific mortality

BACKGROUND

Genome-wide association studies have identified multiple single-nucleotide polymorphsims (SNPs) associated with prostate cancer (PCa). Although these SNPs have been clearly associated with disease risk, their relationship with clinical outcomes is less clear. Our aim was to assess the frequency of known PCa susceptibility alleles within a single institution ascertainment and to correlate risk alleles with disease-specific outcomes.

METHODS

We genotyped 1354 individuals treated for localised PCa between June 1988 and December 2007. Blood samples were prospectively collected and de-identified before being genotyped and matched to phenotypic data. We investigated associations between 61 SNPs and disease-specific end points using multivariable analysis and also determined if SNPs were associated with PSA at diagnosis.

RESULTS

Seven SNPs showed associations on multivariable analysis (P<0.05), rs13385191 with both biochemical recurrence (BR) and castrate metastasis (CM), rs339331 (BR), rs1894292, rs17178655 and rs11067228 (CM), and rs11902236 and rs4857841 PCa-specific mortality. After applying a Bonferroni correction for number of SNPs (P<0.0008), the only persistent significant association was between rs17632542 (KLK3) and PSA levels at diagnosis (P=1.4 × 10(-5)).

CONCLUSIONS

We confirmed that rs17632542 in KLK3 is associated with PSA at diagnosis. No significant association was seen between loci and disease-specific end points when accounting for multiple testing. This provides further evidence that known PCa risk SNPs do not predict likelihood of disease progression.

Association between ABO gene polymorphism (rs505922) and cancer risk: a meta-analysis

Previous studies have showed that ABO blood type is associated with multiple gastrointestinal cancers, including pancreatic cancer. Recently, one single nucleotide polymorphism (SNP) rs505922 in ABO gene has been implicated in susceptibility to pancreatic cancer across different populations, but different results were found in other types of cancer. This meta-analysis aimed to clarify the association. All eligible case-control studies were identified by searching through PubMed and Chinese language databases (CNKI and WanFang) up to September 1, 2014. Pooled estimates (odds ratio) were used to assess the strength of associations in fixed- or random-effects models. A total of nine studies with 10,304 cases and 15,564 controls were included. Overall, SNP rs505922 C allele was confirmed as a risk factor for cancer. Additionally, in further stratified analysis by cancer type, C allele carriers were more likely to have higher risk of pancreatic cancer. This study provided evidence of SNP rs505922 C allele as a strong risk factor of cancer susceptibility, specifically for pancreatic cancer.

Genome-wide association studies in Africans and African Americans: expanding the framework of the genomics of human traits and disease

Genomic research is one of the tools for elucidating the pathogenesis of diseases of global health relevance and paving the research dimension to clinical and public health translation. Recent advances in genomic research and technologies have increased our understanding of human diseases, genes associated with these disorders, and the relevant mechanisms. Genome-wide association studies (GWAS) have proliferated since the first studies were published several years ago and have become an important tool in helping researchers comprehend human variation and the role genetic variants play in disease. However, the need to expand the diversity of populations in GWAS has become increasingly apparent as new knowledge is gained about genetic variation. Inclusion of diverse populations in genomic studies is critical to a more complete understanding of human variation and elucidation of the underpinnings of complex diseases. In this review, we summarize the available data on GWAS in recent African ancestry populations within the western hemisphere (i.e. African Americans and peoples of the Caribbean) and continental African populations. Furthermore, we highlight ways in which genomic studies in populations of recent African ancestry have led to advances in the areas of malaria, HIV, prostate cancer, and other diseases. Finally, we discuss the advantages of conducting GWAS in recent African ancestry populations in the context of addressing existing and emerging global health conditions.

Association between CLPTM1L-TERT rs401681 polymorphism and risk of pancreatic cancer: a meta-analysis

Telomere biology plays a critical and complex role in the initiation and progression of cancer. Several recent studies have provided evidence that rs401681 polymorphisms in intronic region of cleft lip and palate trans-membrane 1-like (CLPTM1L) gene sequence are associated with pancreatic cancer (PC) development, but a comprehensive synopsis is not available. We performed a meta-analysis of 6 case-control studies that included 8,253 pancreatic cancer cases and 37,646 case-free controls. We assessed the strength of the association, using odds ratios (ORs) with 95 % confidence intervals (CIs). Overall, this meta-analysis showed that rs401681 allele T was associated with a significantly increased PC risk (OR = 1.17, 95 % CI = 1.12-1.22, P heterpgeneity = 0.596 and I (2) = 0). Similarly, in the subgroup analysis by ethnicity, a significantly increased risk was found among Asians (OR = 1.15, 95 % CI = 1.07-1.24, P heterpgeneity = 0.297 and I (2) = 8.0 %) and among Caucasian (OR = 1.13, 95 % CI = 1.02-1.26, P heterpgeneity = 0.385 and I (2) = 0). No publication bias was found in the present study. This meta-analysis suggests that T allele of CLPTM1L-telomerase reverse transcriptase rs401681 polymorphism is associated with an increased PC risk, especially among Chinese. Further large and well-designed studies are needed to confirm this association.

Role of solute carrier transporters in pancreatic cancer: a review

Nucleoside analogs such as gemcitabine and 5-fluorouracil are currently the cornerstone of chemotherapy in patients with pancreatic ductal adenocarcinoma (PDAC). Decreased drug transport into tumor cells that may be caused by low expression of membrane proteins, such as solute carrier transporters, represents one of the principal mechanisms of chemotherapy resistance. Individual diversity of multidrug resistance is the major challenge limiting the success of anticancer treatment. Novel biomarkers and pharmacogenomic approaches could further optimize treatment algorithms leading to better survival and lower treatment toxicity in PDAC patients. In this review, the most promising predictive biomarkers from the solute carrier transporter family of membrane transporters and the potential applications for PDAC therapy with nucleoside analogues are summarized.

Genome-wide analysis of the role of copy-number variation in pancreatic cancer risk

Although family history is a risk factor for pancreatic adenocarcinoma, much of the genetic etiology of this disease remains unknown. While genome-wide association studies have identified some common single nucleotide polymorphisms (SNPs) associated with pancreatic cancer risk, these SNPs do not explain all the heritability of this disease. We hypothesized that copy number variation (CNVs) in the genome may play a role in genetic predisposition to pancreatic adenocarcinoma. Here, we report a genome-wide analysis of CNVs in a small hospital-based, European ancestry cohort of pancreatic cancer cases and controls. Germline CNV discovery was performed using the Illumina Human CNV370 platform in 223 pancreatic cancer cases (both sporadic and familial) and 169 controls. Following stringent quality control, we asked if global CNV burden was a risk factor for pancreatic cancer. Finally, we performed in silico CNV genotyping and association testing to discover novel CNV risk loci. When we examined the global CNV burden, we found no strong evidence that CNV burden plays a role in pancreatic cancer risk either overall or specifically in individuals with a family history of the disease. Similarly, we saw no significant evidence that any particular CNV is associated with pancreatic cancer risk. Taken together, these data suggest that CNVs do not contribute substantially to the genetic etiology of pancreatic cancer, though the results are tempered by small sample size and large experimental variability inherent in array-based CNV studies.

Genetic and molecular alterations in pancreatic cancer: implications for personalized medicine

Recent advances in human genomics and biotechnologies have profound impacts on medical research and clinical practice. Individual genomic information, including DNA sequences and gene expression profiles, can be used for prediction, prevention, diagnosis, and treatment for many complex diseases. Personalized medicine attempts to tailor medical care to individual patients by incorporating their genomic information. In a case of pancreatic cancer, the fourth leading cause of cancer death in the United States, alteration in many genes as well as molecular profiles in blood, pancreas tissue, and pancreas juice has recently been discovered to be closely associated with tumorigenesis or prognosis of the cancer. This review aims to summarize recent advances of important genes, proteins, and microRNAs that play a critical role in the pathogenesis of pancreatic cancer, and to provide implications for personalized medicine in pancreatic cancer.

Genome-wide association study identifies common variants in SLC39A6 associated with length of survival in esophageal squamous-cell carcinoma

We conducted a genome-wide scan of SNPs to identify variants associated with length of survival in 1,331 individuals with esophageal squamous-cell carcinoma (ESCC), with associations validated in 2 independent sets including 1,962 individuals with this cancer. We identified rs1050631 in SLC39A6 as associated with the survival times of affected individuals, with the hazard ratio for death from ESCC in the combined sample being 1.30 (95% confidence interval (CI) = 1.19-1.43; P = 3.77 × 10(-8)). rs7242481, located in the 5' UTR of SLC39A6, disturbs a transcriptional repressor binding site and results in upregulation of SLC39A6 expression. Immunohistochemical staining of ESCC tissues showed that higher expression of SLC39A6 protein was correlated with shorter length of survival in individuals with advanced ESCC (P = 0.013). Knockdown of SLC39A6 expression suppressed proliferation and invasion in ESCC cells. These results suggest that SLC39A6 has an important role in the prognosis of ESCC and may be a potential therapeutic target.

Polymorphisms in genes related to one-carbon metabolism are not related to pancreatic cancer in PanScan and PanC4

PURPOSE

The evidence of a relation between folate intake and one-carbon metabolism (OCM) with pancreatic cancer (PanCa) is inconsistent. In this study, the association between genes and single-nucleotide polymorphisms (SNPs) related to OCM and PanCa was assessed.

METHODS

Using biochemical knowledge of the OCM pathway, we identified thirty-seven genes and 834 SNPs to examine in association with PanCa. Our study included 1,408 cases and 1,463 controls nested within twelve cohorts (PanScan). The ten SNPs and five genes with lowest p values (<0.02) were followed up in 2,323 cases and 2,340 controls from eight case-control studies (PanC4) that participated in PanScan2. The correlation of SNPs with metabolite levels was assessed for 649 controls from the European Prospective Investigation into Cancer and Nutrition.

RESULTS

When both stages were combined, we observed suggestive associations with PanCa for rs10887710 (MAT1A) (OR 1.13, 95 %CI 1.04-1.23), rs1552462 (SYT9) (OR 1.27, 95 %CI 1.02-1.59), and rs7074891 (CUBN) (OR 1.91, 95 %CI 1.12-3.26). After correcting for multiple comparisons, no significant associations were observed in either the first or second stage. The three suggested SNPs showed no correlations with one-carbon biomarkers.

CONCLUSIONS

This is the largest genetic study to date to examine the relation between germline variations in OCM-related genes polymorphisms and the risk of PanCa. Suggestive evidence for an association between polymorphisms and PanCa was observed among the cohort-nested studies, but this did not replicate in the case-control studies. Our results do not strongly support the hypothesis that genes related to OCM play a role in pancreatic carcinogenesis.

TERT-CLPTM1L polymorphism rs401681 contributes to cancers risk: evidence from a meta-analysis based on 29 publications

Background

Some common genetic variants of TERT-CLPTM1L gene, which encode key protein subunits of telomerase, have been suggested to play a crucial role in tumorigenesis. The TERT-CLPTM1L polymorphism rs401681 was of special interest for cancers risk but with inconclusive results.

Methodology/Principal Findings

We performed a comprehensive meta-analysis of 29 publications with a total of 91263 cases and 735952 controls. We assessed the strength of the association between rs401681 and overall cancers risk and performed subgroup analyses by cancer type, ethnicity, source of control, sample size and expected power. Rs401681 C allele was found to be associated with marginally increased cancers risk, with per allele OR of 1.04 (95%CI = 1.00–1.08, P_{heterogeneity}<0.001) and an expected power of 1.000. Following further stratified analyses, the increased cancers risk were discovered in subgroups of lung, bladder, prostate, basal cell carcinomas and Asians, while a declined risk of pancreatic cancer and melanoma were detected.

Conclusions/Significance

These findings suggested that rs401681 C allele was a low-penetrance risk allele for the development of cancers of lung, bladder, prostate and basal cell carcinoma, but a potential protective allele for melanoma and pancreatic cancer.