Genetic susceptibility in pancreatic ductal adenocarcinoma

ATP-Binding Cassette Genes Genotype and Expression: A Potential Association with Pancreatic Cancer Development and Chemoresistance?

Genetic polymorphisms in ABC (ATP-binding cassette) transporter genes are associated with differential responses to chemotherapy in various cancers including pancreatic cancer. In this study, four SNPs in the ABCB1, ABCC1, and ABCG2 genes were investigated in normal and pancreatic cancerous specimens. The expression of the three transporters was also analyzed. The TT genotypes of G2677T and C3435T in ABCB1 gene were associated with lower risk of developing pancreatic cancer (P = 0.013, OR = 0.35 and P = 0.015, OR = 0.29, resp.). To our knowledge, this is the first report of the common polymorphisms in the ABCB1 gene affecting the genetic risk of developing pancreatic cancer. Moreover, the expression of ABCB1 in 2677TT and 3435TT carriers was lower compared to the wild-type homozygotes and heterozygotes. A cell viability assay, using standard pancreatic cancer cell lines, revealed that the ABCB1 2677TT-3455TT haplotype was more sensitive than the other haplotypes to gemcitabine. Conclusion. Polymorphisms in ABCB1 G2677T and G3435T were associated with differential susceptibility to pancreatic cancer and may predict responses to chemotherapy.

Individuals at high-risk for pancreatic cancer development: management options and the role of surgery

Pancreatic cancer (PC) is a highly lethal disease. Despite advances regarding the safety and long-term results of pancreatectomies, early diagnosis remains the only hope for cure. This necessitates the implementation of an intensive screening program (based mainly on modern imaging), which - given the incidence of PC - is not cost effective for the general population. However, this screening program is recommended for individuals at high-risk for PC development. Indications for screening include the following three clinical settings: hereditary cancer predisposition syndromes associated with PC, hereditary pancreatitis and familial pancreatic cancer syndrome. The aim of this strategy is to identify pre-invasive (precursor) lesions, which are curable. Surgery is recommended in the presence of recognizable lesion on imaging lesions. Partial (anatomic) pancreatectomy - depending on the location of the suspicious lesion - is the most widely accepted type of surgical intervention in this setting; occasionally, however, total pancreatectomy may be required, in carefully selected patients. Despite that experience still remains limited, there is evidence that this aggressive strategy allows early detection of neoplastic lesions, thereby improving the effectiveness of surgery and prognosis.

Cyclooxygenase-2 polymorphisms and pancreatic cancer susceptibility

OBJECTIVES

DNA sequence variants in the cyclooxygenase-2 (COX-2) gene may lead to altered COX-2 production and/or activity, resulting in interindividual differences in susceptibility to pancreatic cancer. To test this hypothesis, we investigated the relationship between polymorphisms in the COX-2 gene and the risk of pancreatic cancer in a European population.

METHODS

The COX-2 genotypes for 7 single-nucleotide polymorphisms (rs2745557, rs5277, rs2066826, rs4648261, rs4648262, rs2206593, and rs5275) were determined in 162 pancreatic cancer patients and 170 control subjects without cancer who were matched for age and sex. Data analysis was by conditional logistic regression analysis, adjusting for age, sex, and smoking.

RESULTS

Two haplotypes (GGAGGGT and GCGGGGT for rs2745557, rs5277, rs2066826, rs4648261, rs4648262, rs2206593, rs5275, respectively) were more frequent among the patients compared with control subjects (P < 0.024), although no individually statistically significant associations for the 7 single-nucleotide polymorphisms studied were detected.

CONCLUSIONS

Our findings suggest the individual polymorphisms we studied in the COX-2 gene are not associated with risk of pancreatic cancer. However, the finding of a modest association with 2 haplotypes might be consistent with a small effect, which could be also seen at the genotype level had more samples been available.

Susceptibility locus for lung cancer at 15q25.1 is not associated with risk of pancreatic cancer

OBJECTIVES

Four genome-wide association (GWA) studies have found that variation in a region of strong linkage disequilibrium on the long arm of chromosome 15 (15q24-25.1) containing nicotinic acetylcholine receptor genes contributes to lung cancer risk. Because cigarette smoking is a major risk factor for developing both lung cancer and pancreatic cancer, we hypothesized that variation in this region may also modify individual susceptibility to pancreatic cancer.

METHODS

We conducted a case-control study of 523 patients with pathologically confirmed pancreatic adenocarcinoma and 1046 age-, sex-, ethnicity-, and smoking behavior-matched cancer-free controls.

RESULTS

We found that 2 risk single nucleotide polymorphisms reported in the lung cancer GWA studies-rs8034191: A>G and rs1051730: G>A, located in this 15q24-25.1 region-were not associated with risk of pancreatic cancer.

CONCLUSIONS

The results of our study suggest that the 2 single nucleotide polymorphisms at 15q25.1 do not modify pancreatic cancer risk.

The role of tobacco-derived carcinogens in pancreas cancer

The extremely poor outcome from pancreas cancer is well known. However, its aetiology less well appreciated, and the molecular mechanisms underlying this are poorly understood. Tobacco usage is one of the strongest risk factors for this disease, and this is a completely avoidable hazard. In addition, there are well described hereditary diseases which predispose, and familial pancreas cancer. We have sought here to summarise the role of tobacco-derived carcinogens and the mode of their tumorigenic action on the pancreas. There is compelling evidence from animal and human studies (laboratory including cell line studies and epidemiologic) that tobacco derived carcinogens cause pancreas cancer. However, the manner in which they do so is not entirely apparent. There is also compelling evidence that synergism with genetic and other life-style factors-like diet obesity-results in a multifactorial causation of the disease. Ascertaining the role of tobacco carcinogens in the development of this cancer and their interaction with other risk factors will enable novel therapeutic and preventative strategies to improve outcome from this appalling malignancy.

Family history of cancer and tobacco exposure in index cases of pancreatic ductal adenocarcinoma

Aim. To examine interaction between history of cancer in first-degree relatives and tobacco smoking in index patients of pancreatic adenocarcinoma. Methods. We carried out a case-control involving 113 patients with pancreatic adenocarcinoma and 110 controls over a 12-month period at the Freeman Hospital, Newcastle upon Tyne, UK. They were all administered a detailed tobacco exposure questionnaire and a family history questionnaire. We calculated cumulative tobacco exposure and risk for pancreas cancer. Results. Both smokers (OR 3.01 (95% CI: 1.73 to 5.24)) and those with a family history of malignancy (OR 1.98 (95% CI: 1.15–3.38)) were more likely to develop pancreatic cancer. Having more than one first-degree relative with cancer did not significantly further increase the risk of pancreatic cancer. Amongst pancreatic cancer cases, cumulative tobacco exposure was significantly decreased (P = .032) in the group of smokers (current and ex-smokers) who had a family history of malignancy [mean (SD): 30.00 (24.77) pack-years versus 44.69 (28.47) pack-years with no such history]. Conclusions. Individuals with a family history of malignancy are at an increased risk of pancreatic cancer. Furthermore, individuals with a family history of malignancy and who smoke appear to require a lesser degree of tobacco exposure for the development of pancreatic cancer.

Werner syndrome as a hereditary risk factor for exocrine pancreatic cancer: potential role of WRN in pancreatic tumorigenesis and patient-tailored therapy

Advanced age is considered a risk factor for pancreatic cancer, but this relationship at the molecular and genetic level remains unclear. We present a clinical case series focusing on an association between pancreatic adenocarcinoma and Werner syndrome (WS) that is an autosomal recessive genetic disorder characterized by accelerated aging and cancer predisposition, and is caused by loss-of-function mutations in the WS RecQ helicase gene (WRN). Although pancreatic adenocarcinoma mostly occurs in a sporadic fashion, a minority of cases occurs in the context of susceptible individuals with hereditary syndromes. While WS has not been previously recognized as a risk factor for developing malignant tumors of the exocrine pancreas, the clinicopathologic features of three reported patients suggest a contributory role of WRN deficiency in pancreatic carcinogenesis. Molecular genetic analyses support the role of WRN as a tumor suppressor gene, although recent evidence reveals that WRN can alternatively promote oncogenicity depending on the molecular context. Based upon the clinico-pathologic features of these patients and the role of WRN in experimental models, we propose that its loss-of-function predisposes the development of pancreatic adenocarcinoma through epigenetic silencing or loss-of-heterozygosity of WRN. To test this hypothesis, we are investigating the mechanistic role of WRN in pancreatic cancer models including a pancreatic adenocarcinoma cell line generated from a human with WS. These studies are expected to provide new insight into the relationship between aging and pancreatic tumorigenesis, and facilitate development of novel strategies for patient-tailored interventions in this deadly malignancy.

Polymorphisms in tumour necrosis factor alpha (TNFalpha) gene in patients with acute pancreatitis

Proinflammatory cytokines, such as tumour necrosis factor α (TNFα), play fundamental roles in the pathogenesis of acute pancreatitis (AP). The aim of this study was to determine if polymorphisms in the TNFα gene are associated with AP. Two polymorphisms located in the promoter region (positions −308 and −238) in TNFα gene were determined using polymerase chain reaction- (PCR-) restriction fragment length polymorphism (RFLP) methods in 103 patients with AP and 92 healthy controls. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated using logistic regression analysis adjusted for age, sex, BMI and smoking. The frequencies of TNFα polymorphisms were both similar in patients with mild or severe pancreatitis, so were in pancreatitis patients and in controls. We suggest that both SNPs of TNFα are not genetic risk factor for AP susceptibility (OR = 1.63; 95% CI: 1.13−4.01 for TNFα⁻³⁰⁸ and OR = 0.86; 95% CI: 0.75−1.77 for TNFα⁻²³⁸).

The association between glutathione S-transferase gene polymorphisms and pancreatic cancer in a central European Slavonic population

In the first case-control study on pancreatic cancer conducted on 253 cases and 403 controls in the Czech Republic we observed that the GSTP1-codon 105 Val variant allele and the GSTT1-null genotype were associated with an elevated risk for pancreatic cancer (OR = 1.38; 95%CI = 0.96-1.97 and OR = 1.56; 95%CI = 0.93-2.61, respectively). Combination of GSTT1-null and GSTP1-codon 105 Val variants further increased the risk for pancreatic cancer (OR = 2.50; 95%CI = 1.20-5.20). In conclusion, this study suggests population-specific associations of polymorphisms in key biotransformation genes with elevated risk for pancreatic cancer.

ABO blood group and the risk of pancreatic cancer

BACKGROUND

Other than several rare, highly penetrant familial syndromes, genetic risk factors for sporadic pancreatic cancer are largely unknown. ABO blood type is an inherited characteristic that in previous small studies has been associated with the risk of gastrointestinal malignancies.

METHODS

We separately examined the relationship between ABO blood type and the risk of incident pancreatic cancer in two large, independent, prospective cohort studies (the Nurses' Health Study and Health Professionals Follow-up Study) that collected blood group data on 107 503 US health professionals. Hazard ratios for pancreatic cancer by ABO blood type were calculated using Cox proportional hazards models with adjustment for other known risk factors, including age, tobacco use, body mass index, physical activity, and history of diabetes mellitus. All statistical tests were two-sided.

RESULTS

During 927 995 person-years of follow-up, 316 participants developed pancreatic cancer. ABO blood type was associated with the risk of developing pancreatic cancer (P = .004; log-rank test). Compared with participants with blood group O, those with blood groups A, AB, or B were more likely to develop pancreatic cancer (adjusted hazard ratios for incident pancreatic cancer were 1.32 [95% confidence interval {CI} = 1.02 to 1.72], 1.51 [95% CI = 1.02 to 2.23], and 1.72 [95% CI = 1.25 to 2.38], respectively). The association between blood type and pancreatic cancer risk was nearly identical in the two cohorts (P(interaction) = .97). Overall, 17% of the pancreatic cancer cases were attributable to inheriting a non-O blood group (blood group A, B, or AB). The age-adjusted incidence rates for pancreatic cancer per 100 000 person-years were 27 (95% CI = 23 to 33) for participants with blood type O, 36 (95% CI = 26 to 50) for those with blood type A, 41 (95% CI = 31 to 56) for those with blood type AB, and 46 (95% CI = 32 to 68) for those with blood type B.

CONCLUSIONS

In two large, independent populations, ABO blood type was statistically significantly associated with the risk of pancreatic cancer. Further studies are necessary to define the mechanisms by which ABO blood type or closely linked genetic variants may influence pancreatic cancer risk.

ABO blood group and the risk of pancreatic cancer

BACKGROUND

Other than several rare, highly penetrant familial syndromes, genetic risk factors for sporadic pancreatic cancer are largely unknown. ABO blood type is an inherited characteristic that in previous small studies has been associated with the risk of gastrointestinal malignancies.

METHODS

We separately examined the relationship between ABO blood type and the risk of incident pancreatic cancer in two large, independent, prospective cohort studies (the Nurses' Health Study and Health Professionals Follow-up Study) that collected blood group data on 107 503 US health professionals. Hazard ratios for pancreatic cancer by ABO blood type were calculated using Cox proportional hazards models with adjustment for other known risk factors, including age, tobacco use, body mass index, physical activity, and history of diabetes mellitus. All statistical tests were two-sided.

RESULTS

During 927 995 person-years of follow-up, 316 participants developed pancreatic cancer. ABO blood type was associated with the risk of developing pancreatic cancer (P = .004; log-rank test). Compared with participants with blood group O, those with blood groups A, AB, or B were more likely to develop pancreatic cancer (adjusted hazard ratios for incident pancreatic cancer were 1.32 [95% confidence interval {CI} = 1.02 to 1.72], 1.51 [95% CI = 1.02 to 2.23], and 1.72 [95% CI = 1.25 to 2.38], respectively). The association between blood type and pancreatic cancer risk was nearly identical in the two cohorts (P(interaction) = .97). Overall, 17% of the pancreatic cancer cases were attributable to inheriting a non-O blood group (blood group A, B, or AB). The age-adjusted incidence rates for pancreatic cancer per 100 000 person-years were 27 (95% CI = 23 to 33) for participants with blood type O, 36 (95% CI = 26 to 50) for those with blood type A, 41 (95% CI = 31 to 56) for those with blood type AB, and 46 (95% CI = 32 to 68) for those with blood type B.

CONCLUSIONS

In two large, independent populations, ABO blood type was statistically significantly associated with the risk of pancreatic cancer. Further studies are necessary to define the mechanisms by which ABO blood type or closely linked genetic variants may influence pancreatic cancer risk.