CYP1B1 polymorphisms and k-ras mutations in patients with pancreatic ductal adenocarcinoma

Cytochrome P450 1B1: role in health and disease and effect of nutrition on its expression

This review summarizes the available literature stating CYP1B1 to provide the readers with a comprehensive understanding of its role in different diseases, as well as the importance of nutrition in their control in terms of the influence of different nutrients on its expression. CYP1B1, a member of the cytochrome P450 enzyme family is expressed in different human tissues and is known to contribute to different life alarming pathologies. Particularly, till now much attention has been paid to its involvement in the development of primary congenital glaucoma (PCG) and cancer. However, recently there are some reports highlighting CYP1B1 as a potential regulator in energy homeostasis and adipogenesis thus promoting obesity and hypertension as well. Therefore, seeking out effective strategies to modulate the expression of CYP1B1 is a challenging task. In this context, nutrients based strategies will be the best choice as they are mostly harmless and are easily available in one's diet. In conclusion, this article will be helpful in providing a base for further research that is needed to identify the role of CYP1B1 in progression of different diseases, hypertension and obesity in particular, and then to present the effectiveness, mechanisms, and biologic plausibility of nutrients against its expression.

Cigarette Smoke Toxins-Induced Mitochondrial Dysfunction and Pancreatitis Involves Aryl Hydrocarbon Receptor Mediated Cyp1 Gene Expression: Protective Effects of Resveratrol

We previously reported that mitochondrial CYP1 enzymes participate in the metabolism of polycyclic aromatic hydrocarbons and other carcinogens leading to mitochondrial dysfunction. In this study, using Cyp1b1-/-, Cyp1a1/1a2-/-, and Cyp1a1/1a2/1b1-/- mice, we observed that cigarette and environmental toxins, namely benzo[a]pyrene (BaP) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), induce pancreatic mitochondrial respiratory dysfunction and pancreatitis. Our results suggest that aryl hydrocarbon receptor (AhR) activation and resultant mitochondrial dysfunction are associated with pancreatic pathology. BaP treatment markedly inhibits pancreatic mitochondrial oxygen consumption rate (OCR), ADP-dependent OCR, and also maximal respiration, in wild-type mice but not in Cyp1a1/1a2-/- and Cyp1a1/1a2/1b1-/- mice. In addition, both BaP and TCDD treatment markedly affected mitochondrial complex IV activity, in addition to causing marked reduction in mitochondrial DNA content. Interestingly, the AhR antagonist resveratrol, attenuated BaP-induced mitochondrial respiratory defects in the pancreas, and reversed pancreatitis, both histologically and biochemically in wild-type mice. These results reveal a novel role for AhR- and AhR-regulated CYP1 enzymes in eliciting mitochondrial dysfunction and cigarette toxin-mediated pancreatic pathology. We propose that increased mitochondrial respiratory dysfunction and oxidative stress are involved in polycyclic aromatic hydrocarbon associated pancreatitis. Resveratrol, a chemo preventive agent and AhR antagonist, and CH-223191, a potent and specific AhR inhibitor, confer protection against BaP-induced mitochondrial dysfunction and pancreatic pathology.

Genetic variants in carcinogen-metabolizing enzymes, cigarette smoking and pancreatic cancer risk

Individual susceptibility to the toxic effects of cigarette smoke may be modified by inherited variability in carcinogen metabolism. The purpose of the present study was to investigate pancreatic cancer risk associated with cigarette smoking and 33 variants within carcinogen metabolism genes and examine whether these variants modify the association between smoking and pancreatic cancer. A population-based study was conducted with 455 pancreatic cancer cases and 893 controls. Epidemiological and smoking data were collected from questionnaires and variants were genotyped by mass spectrometry. Age- and sex-adjusted odds ratio (ASOR) and multivariate-adjusted odds ratio (MVOR) estimates were obtained using multivariate logistic regression, and interactions between each variant and smoking were investigated. Current smoker status [MVOR = 2.29, 95% confidence interval (95% CI): 1.62, 3.22], 10-27 pack-years (MVOR = 1.57, 95% CI: 1.13, 2.18), >27 pack-years (MVOR = 1.77, 95% CI: 1.27, 2.46) and longer durations of smoking (19-32 years: MVOR = 1.46, 95% CI: 1.05, 2.05; >32 years: MVOR = 1.78, 95% CI: 1.30, 2.45) were associated with increased pancreatic cancer risk. CYP1B1-4390-GG (ASOR = 0.36, 95% CI: 0.15, 0.86) and Uridine 5'-diphospho glucuronosyltransferase 1 family, polypeptide A7-622-CT (ASOR = 0.77, 95% CI: 0.60, 0.99) were associated with reduced risk. N-acetyltransferase 1-640-GT/GG (ASOR = 1.75, 95% CI: 1.00, 3.05), GSTM1 (rs737497)-GG (ASOR = 1.41, 95% CI: 1.02, 1.95), GSTM1 gene deletion (ASOR = 4.89, 95% CI: 3.52, 6.79) and glutathione S-transferase theta-1 gene deletion (ASOR = 4.41, 95% CI: 2.67, 7.29) were associated with increased risk. Significant interactions were observed between pack-years and EPHX1-415 (P = 0.04) and smoking status and N-acetyltransferase 2-857 (P = 0.03). Variants of carcinogen metabolism genes are independently associated with pancreatic cancer risk and may modify the risk posed by smoking.

Detection of k-ras gene mutations in Chinese patients with colorectal cancer

AIM: To investigate k-ras gene mutations and to analyze their clinical significance in Chinese patients with colorectal cancer.

METHODS: A total of 280 surgical specimens taken from patients with colorectal cancer who were treated at Fuzhou General Hospital of Nanjing Military Command between January 2008 and December 2009 and had complete clinical data were used in the study. Six k-ras gene mutations at codon 12 (35G>A, 35G>T, 35G>C, 34G>A, 34G>T, 34G>C) and one at codon 13 (38G>A) were detected by real-time fluorescence quantitative PCR (qPCR) and direct sequencing. A comparison of results obtained by the two methods was then performed.

RESULTS: The overall positive rate of k-ras gene mutations obtained by direct sequencing was 33.57% (94/280), and the positive rate of mutations at codon 12 [4.29% (12/280) for 35G>A, 0.36% (1/280) for 35G>T, 0.36% (1/280) for 35G>C, 2.86% (8/280) for 34G>A, 3.57% (10/280) for 34G>T, and 0.36% (1/280) for 34G>C] was 14.64% (41/280) and 7.5% (21/280) at codon 13. Of 94 patients who were demonstrated to have k-ras gene mutations by direct sequencing, 91 were confirmed by qPCR [sensitivity, 96.8% (91/94)]. Meanwhile, of 186 patients who were demonstrated to have no k-ras gene mutation by direct sequencing, 184 were confirmed by qPCR [specificity, 98.9% (184/186)]. The matching rate between the two methods was 98.2%. K-ras gene mutations were significantly associated with sex and age (both P < 0.05), but not with tumor site, differentiation, depth of invasion, TNM stage, lymph node metastasis, or distant metastasis (all P > 0.05).

CONCLUSION: A high proportion of k-ras gene mutations (33.57%) were detected in Chinese patients with colorectal cancer. qPCR may be an accurate, rapid and simple method for detection of k-ras gene mutations in patients with colorectal cancer. There was no significant correlation between k-ras gene mutations and biological behavior of colorectal cancer, though a higher rate of gene mutations were detected in female patients older than 60 years.

Clinical validity of detecting K-ras mutations for the diagnosis of exocrine pancreatic cancer: a prospective study in a clinically-relevant spectrum of patients

The diagnostic utility of detecting K-ras mutations for the diagnosis of exocrine pancreatic cancer (EPC) has not been properly studied, and few reports have analysed a clinically relevant spectrum of patients. The objective was to evaluate the clinical validity of detecting K-ras mutations in the diagnosis of EPC in a large sample of clinically relevant patients. We prospectively identified 374 patients in whom one of the following diagnoses was suspected at hospital admission: EPC, chronic pancreatitis, pancreatic cysts, and cancer of the extrahepatic biliary system. Mutations in the K-ras oncogene were analysed by PCR and artificial RFLP in 212 patients. The sensitivity and specificity of the K-ras mutational status for the diagnosis of EPC were 77.7% (95% CI: 69.2-84.8) and 78.0% (68.1-86.0), respectively. The diagnostic accuracy was hardly modified by sex and age. In patients with either mutated K-ras or CEA > 5 ng/ml, the sensitivity and specificity were 81.0% (72.9-87.6) and 62.6% (72.9-87.6), respectively. In patients with mutated K-ras and CEA > 5 ng/ml the sensitivity was markedly reduced. In comparisons with a variety of non-EPC patient groups sensitivity and specificity were both always greater than 75%. In this clinically relevant sample of patients the sensitivity and specificity of K-ras mutations were not sufficiently high for independent diagnostic use. However, it seems premature to rule out the utility of K-ras analysis in conjunction with other genetic and 'omics' technologies.

In pancreatic ductal adenocarcinoma blood concentrations of some organochlorine compounds and coffee intake are independently associated with KRAS mutations

While KRAS activation is a fundamental initiating event in the aetiopathogenesis of pancreatic ductal adenocarcinoma (PDA), environmental factors influencing the occurrence and persistence of KRAS mutations remain largely unknown. The objective was to test the hypothesis that in PDA there are aetiopathogenic relationships among concentrations of some organochlorine compounds (OCs) and the mutational status of the KRAS oncogene, as well as among the latter and coffee intake. Incident cases of PDA were interviewed and had blood drawn at hospital admission (N = 103). OCs were measured by high-resolution gas chromatography with electron capture detection. Cases whose tumours harboured a KRAS mutation had higher concentrations of p,p'-dichlorodiphenyltrichloroethane (DDT), p,p'-dichlorodiphenyldichloroethene (DDE) and polychlorinated biphenyls (PCBs) 138, 153 and 180 than cases with wild-type KRAS, but differences were statistically significant only for p,p'-DDT and PCBs 138 and 153. The association between coffee intake and KRAS mutations remained significant (P-trend < 0.015) when most OCs where accounted for. When p,p'-DDT, PCB 153, coffee and alcohol intake were included in the same model, all were associated with KRAS (P = 0.042, 0.007, 0.016 and 0.025, respectively). p,p'-DDT, p,p'-DDE and PCB 138 were significantly associated with the two most prevalent KRAS mutations (Val and Asp). OCs and coffee may have independent roles in the aetiopathogenesis of PDA through modulation of KRAS activation, acquisition or persistence, plausibly through non-genotoxic or epigenetic mechanisms. Given that KRAS mutations are the most frequent abnormality of oncogenes in human cancers, and the lifelong accumulation of OCs in humans, refutation or replication of the findings is required before any implications are assessed.

Correcting serum concentrations of organochlorine compounds by lipids: alternatives to the organochlorine/total lipids ratio

INTRODUCTION

When studying the effects of organochlorine compounds (OCs) on human health it is common to correct serum concentrations of OC by total lipids (TL). However, the relationship between serum OCs and serum TL is far from established in many diseases, including several cancers. Our aim was to analyze the relationship between serum OC and TL in patients with pancreatic ductal adenocarcinoma (PDA), and to explore several alternatives to perform the OC lipid correction.

METHODS

Incident cases of PDA were interviewed and had blood drawn soon around hospital admission (n=144). Serum concentrations of OCs were analysed by high-resolution gas chromatography with electron-capture detection.

RESULTS

Most patients with high TL had moderate or low concentrations of OCs. By contrast, the variability of OC values among patients with normal TL was large. Correlations were of a similar magnitude between OC and TL and between OC and total cholesterol; while these correlations were weak (all Spearman's rho<0.3 and R(2)<0.11), no OC were significantly correlated with triglycerides. Although all alternatives to the OC/TL linear ratio were statistically significant for at least one OC, their R(2) was always below 10%.

CONCLUSIONS

In patients with severe diseases as PDA, linear correction of OC by TL as commonly performed in epidemiologic studies may be inappropriate. Results contribute to the scant literature on the rationale to correct serum concentrations of OC by lipids. They suggest that it is unwarranted to routinely correct OC by TL, offer ways to assess such need, and present alternatives as no TL correction, correction by total cholesterol only or use of different statistical models.

Timing of blood extraction in epidemiologic and proteomic studies: results and proposals from the PANKRAS II Study

There are no consensus guidelines or standards for epidemiologic and '-omics' studies using blood biomarkers on how to report the timing of extraction of blood samples. However, disease-induced changes in blood concentrations of exogenous and endogenous compounds may bias studies. The aim of the present report is to describe the timing of blood collection with respect to a variety of relevant clinical events in the PANKRAS II Study, and to suggest ways to display graphically the quantitative information. Subjects were 167 incident cases of exocrine pancreatic cancer prospectively recruited in five teaching hospitals in eastern Spain. Over 80% of patients had blood extracted during the first 6 months since onset of cancer symptoms, and 82% within the first month of admission to a study hospital. Over 80% of cases had blood drawn after an ultrasound, a CT scan or an ERCP, 25% after a laparotomy, and 37% after treatment onset. All three intervals from blood extraction to diagnosis, to treatment onset and to interview had a median of 0 days, and 88% of cases had blood drawn within 2 weeks of diagnosis. Over 72% of cases had concentrations of total lipids in the medium, normal range. Results suggest ways to report intervals involving blood biomarkers and may contribute to develop consensus guidelines and standards on the collection of blood samples in epidemiologic and '-omics' research.