Biomarkers in cancer epidemiology: an integrative approach

The Relationship of ABCB1/MDR1 and CYP1A1 Variants with the Risk of Disease Development and Shortening of Overall Survival in Patients with Multiple Myeloma

(1) Background: The aim of our study was to analyze the possible relationship of ABCB1 and CYP1A1 gene variants with susceptibility and outcome of multiple myeloma (MM); (2) Methods: Genomic DNA samples from 110 newly-diagnosed MM patients and 100 healthy blood donors were analyzed by methods-PCR-RFLP (for ABCB1 3435C > T, CYP1A1 6235T > C-m1), automated DNA sequencing (for ABCB1 1236C > T, 2677G > T/A) and allele-specific PCR (for CYP1A1 4889A > G-m2); (3) Results: The genotypic frequencies of CYP1A1 4889A > G variant were not in Hardy-Weinberg equilibrium for MM patients. The presence of m1 and m2 CYP1A1 alleles decreased the risk of MM-OR = 0.49 (p = 0.011) and OR = 0.27 (p = 0.0003), respectively. In turn, TT genotype (ABCB1 2677G > T/A) increased the risk of this disease (p = 0.007). In the multivariate Cox analysis CT + TT genotypes (ABCB1 3435C > T) were associated with decreased risk of death (HR = 0.29, p = 0.04). In log-rank test in patients with CT genotype (ABCB1 3435C > T) was observed association of overall survival with the type of treatment; (4) Conclusions: Our findings suggest that T-alleles of ABCB1 2677G > T/A and m1/m2 alleles of CYP1A1 affected the susceptibility of MM. Moreover, T-allele of ABCB1 3435C > T might be independent positive prognostic factor in MM.

Excessive matrix metalloprotease-mediated degradation of interstitial tissue (type I collagen) independently predicts short-term survival in an observational study of postmenopausal women diagnosed with cancer

Extensive tissue remodeling mediated by matrix metalloproteases (MMPs) is an important part of cancer. The aim of this study was to investigate whether serum biomarkers reflecting MMP-mediated degradation of type I collagen (C1M), type IV collagen (C4M) and citrullinated vimentin (VICM) were predictive of cancer-specific mortality. Between 1999 and 2001, 5855 Danish postmenopausal women participated in The Prospective Epidemiologic Risk Factor (PERF I) study. Demographics and serum samples were collected at enrolment. Cancer diagnosis, and cause and time of death were obtained from Danish registries. C1M, C4M and VICM were measured by ELISA. Hazard ratios (HR) and Kaplan-Meier curves were applied to assess mortality at 3 and 12 years of follow-up for women diagnosed with cancer within 3 years from blood sampling. Within 3 years from blood sampling, 250 women had been diagnosed with cancer. C1M and VICM were associated with survival over time at 3 years of follow-up. Only C1M was predictive of mortality at 3 years follow-up: the adjusted HR was 2.65 [95% CI: 1.08-6.51]. In conclusion, C1M and VICM are associated with survival in postmenopausal women with cancer, and C1M is an independent risk factor for cancer-specific mortality. Thus, quantification of tissue remodeling is important in cancer.

Genotypes of CYP1A1, SULT1A1 and SULT1A2 and risk of squamous cell carcinoma of esophagus: outcome of a case-control study from Kashmir, India

Studies on associations of various polymorphism in xenobiotic metabolizing genes with different cancers including esophageal squamous cell carcinoma (ESCC) are mixed and inconclusive. To evaluate the association of CYP1A1*4, SULT1A1*2 and SULT1A2*2 genotypes with ESCC risk and their modifying effects on different risk factors of ESCC, we conducted a case-control study in Kashmir, India, an area with relative high incidence of ESCC. We recruited 404 histopathologically confirmed ESCC cases, and equal number of controls, individually matched for sex, age and district of residence to respective case. Information was obtained on various dietary, lifestyle and environmental factors in face-to-face interviews, using a structured questionnaire, from each subject. Genotypes were analyzed by polymerase chain reaction, restriction fragment length polymorphism and direct sequencing. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs). A higher risk was observed in the subjects who harbored variant genotype of CYP1A1*4 (OR = 2.06; 95% CI: 1.28-3.32); and the risk was further enhanced in ever smokers (OR = 3.47; 95% CI: 1.62-7.42), adobe dwellers (OR = 6.71; 95% CI: 3.02-14.89), and biomass fuel users (OR = 5.11; 95% CI: 1.34-19.50). We did not find any significant differences in the polymorphic variants of SULT1A1*2 and SULT1A2*2 between cases and controls. The study indicates that, unlike SULT1A1*2 and SULT1A2*2, the polymorphism of CYP1A1*4 is associated with ESCC risk. However, replicative studies with larger sample size are needed to substantiate our findings.

Blood-borne biomarkers and bioindicators for linking exposure to health effects in environmental health science

Environmental health science aims to link environmental pollution sources to adverse health outcomes to develop effective exposure intervention strategies that reduce long-term disease risks. Over the past few decades, the public health community recognized that health risk is driven by interaction between the human genome and external environment. Now that the human genetic code has been sequenced, establishing this "G × E" (gene-environment) interaction requires a similar effort to decode the human exposome, which is the accumulation of an individual's environmental exposures and metabolic responses throughout the person's lifetime. The exposome is composed of endogenous and exogenous chemicals, many of which are measurable as biomarkers in blood, breath, and urine. Exposure to pollutants is assessed by analyzing biofluids for the pollutant itself or its metabolic products. New methods are being developed to use a subset of biomarkers, termed bioindicators, to demonstrate biological changes indicative of future adverse health effects. Typically, environmental biomarkers are assessed using noninvasive (excreted) media, such as breath and urine. Blood is often avoided for biomonitoring due to practical reasons such as medical personnel, infectious waste, or clinical setting, despite the fact that blood represents the central compartment that interacts with every living cell and is the most relevant biofluid for certain applications and analyses. The aims of this study were to (1) review the current use of blood samples in environmental health research, (2) briefly contrast blood with other biological media, and (3) propose additional applications for blood analysis in human exposure research.

Extracellular vesicles: potential applications in cancer diagnosis, prognosis, and epidemiology

Both normal and diseased cells continuously shed extracellular vesicles (EVs) into extracellular space, and the EVs carry molecular signatures and effectors of both health and disease. EVs reflect dynamic changes that are occurring in cells and tissue microenvironment in health and at a different stage of a disease. EVs are capable of altering the function of the recipient cells. Trafficking and reciprocal exchange of molecular information by EVs among different organs and cell types have been shown to contribute to horizontal cellular transformation, cellular reprogramming, functional alterations, and metastasis. EV contents may include tumor suppressors, phosphoproteins, proteases, growth factors, bioactive lipids, mutant oncoproteins, oncogenic transcripts, microRNAs, and DNA sequences. Therefore, the EVs present in biofluids offer unprecedented, remote, and non-invasive access to crucial molecular information about the health status of cells, including their driver mutations, classifiers, molecular subtypes, therapeutic targets, and biomarkers of drug resistance. In addition, EVs may offer a non-invasive means to assess cancer initiation, progression, risk, survival, and treatment outcomes. The goal of this review is to highlight the current status of information on the role of EVs in cancer, and to explore the utility of EVs for cancer diagnosis, prognosis, and epidemiology.

Feasibility of linking population-based cancer registries and cancer center biorepositories

PURPOSE

Biospecimen-based research offers tremendous promise as a way to increase understanding of the molecular epidemiology of cancers. Population-based cancer registries can augment this research by providing more clinical detail and long-term follow-up information than is typically available from biospecimen annotations. In order to demonstrate the feasibility of this concept, we performed a pilot linkage between the California Cancer Registry (CCR) and the University of California, Davis Cancer Center Biorepository (UCD CCB) databases to determine if we could identify patients with records in both databases.

METHODS

We performed a probabilistic data linkage between 2180 UCD CCB biospecimen records collected during the years 2005-2009 and all CCR records for cancers diagnosed from 1988-2009 based on standard data linkage procedures.

RESULTS

The 1040 UCD records with a unique medical record number, tissue site, and pathology date were linked to 3.3 million CCR records. Of these, 844 (81.2%) were identified in both databases. Overall, record matches were highest (100%) for cancers of the cervix and testis/other male genital system organs. For the most common cancers, matches were highest for cancers of the lung and respiratory system (93%), breast (91.7%), and colon and rectum (89.5%), and lower for prostate (72.9%).

CONCLUSIONS

This pilot linkage demonstrated that information on existing biospecimens from a cancer center biorepository can be linked successfully to cancer registry data. Linkages between existing biorepositories and cancer registries can foster productive collaborations and provide a foundation for virtual biorepository networks to support population-based biospecimen research.

TP53 mutations in human cancer: database reassessment and prospects for the next decade

More than 50% of human tumors carry TP53 gene mutations and in consequence more than 45,000 somatic and germline mutations have been gathered in the UMD TP53 database (http://p53.fr). Analyses of these mutations have been invaluable for bettering our knowledge on the structure-function relationships within the TP53 protein and the high degree of heterogeneity of the various TP53 mutants in human cancer. In this review, we discuss how with the release of the sequences of thousands of tumor genomes issued from high-throughput sequencing, the description of novel TP53 mutants is now reaching a plateau indicating that we are close to the full set of mutants that target the elusive tumor-suppressive activity of this protein. We performed an extensive and thorough analysis of the TP53 mutation database, focusing particularly on specific sets of mutations that were overlooked in the past because of their low frequencies, for example, synonymous mutations, splice mutations, or mutations-targeting residues subject to posttranslational modifications. We also discuss the evolution of the statistical methods used to differentiate TP53 passenger mutations and artifactual data from true mutations, a process vital to the release of an accurate TP53 mutation database that will in turn be an invaluable tool for both clinicians and researchers.

MICROFLUIDIC DEVICES FOR LABEL-FREE AND NON-INSTRUMENTED QUANTITATION OF UNAMPLIFIED NUCLEIC ACIDS BY FLOW DISTANCE MEASUREMENT

Timely biomarker quantitation has potential to improve human health but current methods have disadvantages either in terms of cost and complexity for benchtop instruments, or reduced performance in quantitation and/or multiplexing for point-of-care systems. We previously developed microfluidic devices wherein visually observed flow distances correlated with a model analyte's concentration.1 Here, we significantly expand over this prior result to demonstrate the measurement of unamplified DNA analogues of microRNAs (miRNAs), biomarkers whose levels can be altered in disease states. We have developed a method for covalently attaching nucleic acid receptors on poly(dimethylsiloxane) microchannel surfaces by silane and cross-linker treatments. We found a flow distance dependence on target concentrations from 10 μg/mL to 10 pg/mL for DNA in both buffer and synthetic urine. Moreover, flow time in addition to flow distance is correlated with target concentration. We also observed longer flow distances for single-base mismatches compared to the target sequence at the same concentration, indicating that our approach can be used to detect point mutations. Finally, experiments with DNA analogues of miRNA biomarkers for kidney disease (mir-200c-3p) and prostate cancer (mir-107) in synthetic urine showed the ability to detect these analytes near clinically relevant levels. Our results demonstrate that these novel microfluidic assays offer a simple route to sensitive, amplification-free nucleic acid quantitation, with strong potential for point-of-care application.

Inter-ethnic differences in genetic polymorphisms of xenobiotic-metabolizing enzymes (CYP1A1, CYP2D6, NAT1 and NAT2) in healthy populations: correlation with the functional in silico prediction

Several studies have shown that many polymorphisms of the xenobiotic-metabolizing enzymes (XME) affect either enzymatic functions or are associated with various aspects of human health. Owing to the presence of these single nucleotide variants (SNVs), differences in detoxification capacity have been observed between many ethnicities. The aim of this investigation was to study the prevalence of four polymorphisms in XME among various ethnic groups. Attention was focused on polymorphisms of CYP2D6 (rs1058172, G>A, p.Arg365His), CYP1A1 (rs4646421, c.-26-728C>T), NAT1 (rs4921880, c.-85-1014T>A) and NAT2 (rs1208, A>G, p.Arg268Lys). These polymorphisms were analyzed in 261 healthy Tunisians individuals in comparison with different ethnic backgrounds from hapmap database. In addition, in silico functional prediction was also performed to determine the loss of function variants. Our results demonstrated that population's origins widely affect the genetic variability of XME enzymes and Tunisians show a characteristic pattern. In silico predictions showed a deleterious effect for p.Arg268Lys substitution on CYP2D6 function, findings confirmed its key role played in cancer susceptibility. These data show that detoxification genes structures depend on the studied population. This suggests that ethnic differences impact on disease risk or response to drugs and therefore should be taken into consideration in genetic association studies focusing on XME enzymes. Our results provide the first report on these SNV in Tunisian population and could be useful for further epidemiological investigations including targeted therapy.

CYP1A1 and CYP2E1 genotypes and risk of esophageal squamous cell carcinoma in a high-incidence region, Kashmir

The study analyzed the relationship between genetic polymorphisms of phase I xenobiotic metabolizing enzymes, cytochromes P450 (CYP) 1A1 and CYP2E1 and esophageal squamous cell carcinoma (ESCC) in Kashmir, India. The different genotypes of CYP1A1 and CYP2E1 were analyzed by polymerase chain reaction and restriction fragment length polymorphism in 526 ESCC cases and equal number of matched controls. Conditional logistic regression models were used to assess the association of various genotypes with ESCC, gene-gene, and gene-environment interactions. High risk of ESCC was found in participants who carried CYP1A1 Val/Val genotype (OR=2.87; 95 % CI=1.00-8.44) and the risk increased in such individuals when c1/c1 of CYP2E1 genotype was also present (OR=5.68; 95 % CI=1.09-29.52). Risk due to CYP1A1 Val/Val genotype was further enhanced (OR=8.55; 95 % CI=1.86-42.20) when the analysis was limited to ever smokers. Participants who carried CYP2E1 c1/c2 genotype showed an inverse relation (OR=0.27; 95 % CI=0.17-0.43) with ESCC. The inverse association of CYP2E1 c1/c2 genotype was retained when CYP1A1 Ile/Ile was also present (OR=0.18; 95 % CI=0.09-0.32), as well as when analysis was limited to ever smokers (OR=0.45; 95 % CI=0.23-0.90). Significant interaction was found between CYP1A1 (Val/Val) and CYP2E1 (c1/c1) genotypes (OR=1.30; 95 % CI=1.12-1.51; P=0.001) and between CYP1A1 (Val/Val) and smoking (OR=1.31; 95 % CI=1.01-1.69; P=0.043). The study suggests CYP1A1 Val/Val and CYP2E1 c1/c1 genotypes are significantly associated with ESCC risk.

Association of CYP1A1 and CYP2D6 gene polymorphisms with head and neck cancer in Tunisian patients

The purpose of this study was to investigate the relationship between head and neck cancer (HNC) and environmental agents and polymorphisms in CYP1A1, CYP2D6, NAT1 and NAT2 metabolic enzymes genes. To the best of our knowledge, this is the first report on polymorphisms in CYP1A1 6310C>T, CYP2D6 Arg365His, NAT1 52936A>T and NAT2 Arg268Lys (NAT2*12A) genes and susceptibility to HNC in Tunisian population. We study the prevalence of these polymorphisms in 169 patients with HNC and 261 control subjects using polymerase chain reaction based methods in a Tunisian population. We detected an association between HNC and CYP1A1 6310C>T (TT) and CYP2D6 Arg365His (His/His) variant carriers (OR 1.75, P = 0.008 and OR 1.66, P = 0.016, respectively). No association was found between the polymorphisms genotypes of NAT1 52936T>A and NAT2 Arg268Lys and risk of HNC. An association between HNC and CYP1A1 (TT) genotype was found among patients with smoking (P = 0.011) and drinking habit (P = 0.009). The combinations of NAT1 (AT or AA) and NAT2 (AA) at-risk genotypes increased HNC risk (OR 4.23, P = 0.005 and OR 3.60, P = 0.048, respectively). However, the combinations of CYP1A1 (AA) and CYP2D6 (CC) genotypes decreased risk of HNC (OR 0.20; P = 0.006). Genetic polymorphisms in CYP1A1 and CYP2D6 may significantly associate with HNC in the Tunisian population. The results of this study suggest a possible gene-environment interaction for certain carcinogen metabolizing enzymes, but larger studies that fully evaluate the interaction are needed.

Folate deficiency is not associated with increased mitochondrial genomic instability: results from dietary intake and lymphocytic mtDNA 4977-bp deletion in healthy young women in Italy

The mitochondrial DNA (mtDNA) 4977-bp deletion is a biomarker of mitochondrial genomic instability. It is frequently detected in a number of sporadic diseases, and it accumulates in many tissues during aging. Folic acid plays an important role in the maintenance of genomic stability in mammals. The aim of the present cross-sectional study was to characterise the levels of the mtDNA deletion in the lymphocytes of healthy young women, taking into account folate intake, red blood cell (RBC) folate levels and the distribution of the methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism. Folate intake was estimated by a food frequency questionnaire. Determination of the MTHFR C677T polymorphism and of the mtDNA deletion was performed by real-time polymerase chain reaction analysis. A total of 476 women were enrolled. Low levels of deletion were found (mean ΔCt = 1.24). After multivariate analysis, results did not show any significant relationship between age, smoking habits, pregnancy status, nutritional status, inadequate folate intake, folate deficiency, use of folic acid supplements, MTHFR C677T polymorphism and mtDNA 4977-bp deletions. The lack of association between inadequate folate intake, folate deficiency and mitochondrial genomic instability was confirmed also considering reference values of folate based on DNA damage prevention. Our results indicate that mtDNA 4977-bp deletions are maintained at low levels in lymphocytes of young healthy women despite the wide range of variation of folate intakes and folate status. Future studies, carefully designed to address limits and methodological issues related to variation of this biomarker as an effect of different dietary patterns and of folate status, could provide further insight on the specific mechanisms that are acting in lymphocytes of healthy subjects under observed folate intake.

Association between CYP1A1 Ile462Val variation and acute leukemia risk: meta-analyses including 2164 cases and 4160 controls

BACKGROUND

Previously, CYP1A1 Ile462Val polymorphism has been indicated to be a risk factor for several malignancies. Increasing reports have focused on the association of CYP1A1 Ile462Val polymorphisms with susceptibility to acute leukemia and have generated controversial results. The goal of the present study was to derive a more precise estimation of the relationship.

METHODS

Relevant literature has been rigorously searched and screened. Eligible studies were identified for the period up to Apr 2012. Meta-analyses evaluating the association of CYP1A1 Ile462Val variation with acute leukemia were carried out. Subgroup analyses on ethnicity, clinical types and source of controls were further performed.

RESULTS

A total of thirteen publications including fourteen case-control studies with 2164 cases and 4160 controls were selected for analysis. The overall data indicated a significant association of CYP1A1 Ile462Val polymorphism with acute leukemia risk (Val/Val vs Ile/Ile OR = 1.49; 95% CI = 1.11-1.98; dominant model: OR = 1.26; 95% CI = 1.05-1.51; recessive model: OR = 1.38; 95% CI = 1.04-1.83). In subgroup analysis on ethnicity, increased risk was shown among mixed ethnicities (Val/Val vs Ile/Ile: OR = 2.36; 95% CI = 1.46-3.82; dominant model: OR = 1.37; 95% CI = 1.01-1.86; recessive model: OR = 2.20; 95% CI = 1.37-3.53) but not Asians or Caucasians. In subgroup analysis on clinical types, increased risk was observed in the acute lymphocytic leukemia (ALL) subgroup (Val/Val vs Ile/Ile: OR = 2.06; 95% CI = 1.42-3.01; recessive model: OR = 1.91; 95% CI = 1.32-2.76) but not in the acute myeloid leukemia (AML) subgroup.

CONCLUSION

The results of the present study suggest that CYP1A1 Ile462Val polymorphism might be a low-penetrant risk factor for acute leukemia. Subgroup analyses suggest that homozygous Val/Val alleles might modify the susceptibility to ALL.

CYP1A1 MspI polymorphism and acute myeloid leukemia risk: meta-analyses based on 5018 subjects

Background

Evidence indicates that CYP1A1 MspI polymorphism might be a possible risk factor for several malignancies. A growing body of literature has been devoted to the association of CYP1A1 MspI polymorphism with acute myeloid leukemia (AML). However, the results remain conflicting. The aim of the present study was to derive a more precise estimation of the relationship.

Methods

Meta-analyses assessing the association of CYP1A1 MspI variation with AML were conducted and subgroup analyses on ethnicity and age groups were further performed. Eligible studies were identified for the period up to May 2012.

Results

A total of ten case–control studies including 1330 cases and 3688 controls were selected for analysis. The overall data failed to indicate a significant association of CYP1A1 MspI polymorphism with AML risk (C vs T: OR = 1.13; 95%CI = 0.87-1.48; CC vs TT: OR = 1.72; 95%CI = 0.99-3.01; CC + TC vs TT: OR = 1.16; 95%CI = 0.86-1.55). In subgroup analysis stratified by ethnicity, significant AML risk was shown among Asians (CC + TC vs TT: OR = 1.33; 95%CI = 1.09-1.62) but not Caucasians or mixed races. In subgroup analysis regarding age groups, no associations were observed in either the childhood AML or the adult AML subgroups.

Conclusion

The results of the present study suggested that CYP1A1 MspI polymorphism might be a risk factor for AML among Asians. Further investigations are needed to confirm the conclusions.

NAT2 polymorphisms with oral carcinoma susceptibility: a meta-analysis

Published data have implicated NAT2 polymorphisms as risk factors for various cancers. A number of studies have focused on the association of NAT2 polymorphisms with susceptibility to oral carcinoma and have yielded inconclusive results. The aim of the present study was to derive a more precise estimation of the relationship. We first carried out a deliberate search in the databases without a language limitation, covering all papers published up to Dec 2011. A total of seven case-control studies including 1,379 cases and 1,868 controls were selected and the relevant data were extracted for systematic meta-analyses. No significant association was found for the overall data (OR: 1.04, 95 % CI: 0.79-1.39). In subgroup analyses according to ethnicity, slow acetylators might increase oral cancer risk among Asians (OR: 1.38, 95 % CI: 1.04-1.82) but not Caucasians or Mixed races. The data suggested that NAT2 polymorphisms might be a low-penetrant risk factor for oral carcinoma in Asians.

Integration of gene chip and topological network techniques to screen a candidate biomarker gene (CBG) for predication of the source water carcinogenesis risks on mouse Mus musculus

Screening of a candidate biomarker gene (CBG) to predicate the carcinogenesis risks in the Yangtze River source of drinking water in Nanjing area (YZR-SDW-NJ) on mouse (Mus musculus) was conducted in this research. The effects of YZR-SDW-NJ on the genomic transcriptional expression levels were measured by the GeneChip(®) Mouse Genome and data treated by the GO database analysis. The 298 genes discovered as the differently expressed genes (DEGs) were down-regulated and their values were ≤-1.5-fold. Of the 298 DEGs, 25 were cancer-related genes selected as the seed genes to build a topological network map with Genes2Networks software, only 7 of them occurred at the constructed map. Smad2 gene was at the constructed map center and could be identified as a candidate biomarker gene (CBG) primarily which involves the genesis and development of colorectal, leukemia, lung and prostate cancers directly. Analysis of the gene signal pathway further approved that smad2 gene had the relationships closely to other 16 cancer-related genes and could be used as a CBG to indicate the carcinogenic risks in YZR-SDW-NJ. The data suggest that integration of gene chip and network techniques may be a way effectively to screen a CBG. And the parameter values for further judgment of the CBG through signal pathway relationship analysis also will be discussed.

Variability in estrogen-metabolizing genes and their association with genomic instability in untreated breast cancer patients and healthy women

In the present study, we investigated the relationship between polymorphisms in the estrogen-metabolizing genes CYP17, CYP1B1, CYP1A1, and COMT and genomic instability in the peripheral blood lymphocytes of 62 BC patients and 62 controls considering that increased or prolonged exposure to estrogen can damage the DNA molecule and increase the genomic instability process in breast tissue. Our data demonstrated increased genomic instability in BC patients and that individuals with higher frequencies of MN exhibited higher risk to BC when belonging Val/Met genotype of the COMT gene. We also observed that CYP17 and CYP1A1 polymorphisms can modify the risk to BC depending on the menopause status. We can conclude that the genetic background in estrogen metabolism pathway can modulate chromosome damage in healthy controls and patients and thereby influence the risk to BC. These findings suggest the importance to ally biomarkers of susceptibility and effects to estimate risk groups.

Epidemiology of lung cancer in women: risk factors, survival, and screening

OBJECTIVE

Lung cancer remains the leading cause of cancer mortality in both men and women. Tobacco use causes the vast majority of lung cancer in women but does not explain all cases, because about one in five women who develop lung cancer have never smoked.

CONCLUSION

Environmental exposures, genetic predisposition, hormonal factors, and viral infection may all play a role in lung cancer in women. A better understanding may provide an avenue to more effective screening, diagnosis, and therapy.

Inhibiting Proliferation in KB Cancer Cells by RNA Interference-Mediated Knockdown of Nicotinamide N-Methyltransferase Expression

The enzyme Nicotinamide N-methyltransferase (NNMT) catalyzes the methylation of nicotinamide and other pyridines, playing a pivotal role in the biotransformation and detoxification of many drugs and xenobiotic compounds. Several tumours have been associated with abnormal NNMT expression, however its role in tumour development remains largely unknown. In this study we investigated expression levels of Nicotinamide N-methyltransferase in a cancer cell line and we evaluated the effect of shRNA-mediated silencing of NNMT on cell proliferation. Cancer cells were examined for NNMT expression by semiquantitative RT-PCR and Western blot analysis. A HPLC-based catalytic assay was performed to assess enzyme activity. Cells were transfected with four shRNA plasmids against NNMT and control cells were treated with transfection reagent only (mock). The efficiency of gene silencing was detected by Real-Time PCR and Western blot analysis. MTT cell proliferation assay and the soft agar colony formation assay were then applied to investigate the functional changes in cancerous cell. NNMT mRNA was detected in cancer cells, showing a very high expression level. In keeping with the results of RT-PCR analysis, the protein level and NNMT enzyme activity were particularly high in KB cells. ShRNA vectors targeted against NNMT efficiently suppressed gene expression, showing inhibition observed at both the mRNA and protein levels. Down-regulation of NNMT significantly inhibited cell proliferation and decreased colony formation ability on soft agar. The present data support the hypothesis that the enzyme plays a role in tumour expansion and its inhibition could represent a possible molecular approach to the treatment of cancer.

DNA repair genes XRCC1 and XRCC3 polymorphisms and their relationship with the level of micronuclei in breast cancer patients

Breast cancer (BC) is the most prevalent type worldwide, besides being one of the most common causes of death among women. It has been suggested that sporadic BC is most likely caused by low-penetrance genes, including those involved in DNA repair mechanisms. Furthermore, the accumulation of DNA damage may contribute to breast carcinogenesis. In the present study, the relationship between two DNA repair genes, viz., XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) polymorphisms, and the levels of chromosome damage detected in 65 untreated BC women and 85 healthy controls, was investigated. Chromosome damage was evaluated through micronucleus assaying, and genotypes determined by PCR-RFLP methodology. The results showed no alteration in the risk of BC and DNA damage brought about by either XRCC1 (Arg399Gln) or XRCC3 (Thr241Met) action in either of the two groups. Nevertheless, on evaluating BC risk in women presenting levels of chromosome damage above the mean, the XRCC3Thr241Met polymorphism was found to be more frequent in the BC group than in the control, thereby leading to the conclusion that there is a slight association between XRCC3 (241 C/T) genotypes and BC risk in the subgroups with higher levels of chromosome damage.

UVA activation of N-dialkylnitrosamines releasing nitric oxide, producing strand breaks as well as oxidative damages in DNA, and inducing mutations in the Ames test

We investigated the photo-mutagenicity and photo-genotoxicity of N-dialkylnitrosamines and its mechanisms of UVA activation. With simultaneous irradiation of UVA, photo-mutagenicity of seven N-dialkylnitrosamines was observed in Ames bacteria (Salmonella typhimurium TA1535) in the absence of metabolic activation. Mutagenicity of pre-irradiated N-dialkylnitrosamines was also observed with S. typhimurium hisG46, TA100, TA102 and YG7108 in the absence of metabolic activation. UVA-mediated mutation with N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) decreased by adding either the NO or OH radical scavenger. When superhelical DNA was irradiated with N-dialkylnitrosamines, nicked circular DNA appeared. Ten N-dialkylnitrosamines examined produced strand breaks in the treated DNA in the presence of UVA. The level of single-strand breaks in phiX174 DNA mediated by N-nitrosomorpholine (NMOR) and UVA decreased by adding either a radical scavenger or superoxide dismutase. When calf thymus DNA was treated with N-dialkylnitrosamines (NDMA, NDEA, NMOR, N-nitrosopyrrolidine (NPYR) and N-nitrosopiperidine (NPIP)) and UVA, the ratio of 8-oxodG/dG in the DNA increased. Action spectra were obtained to determine if nitrosamine acts as a sensitizer of UVA. Both mutation frequency and NO formation were highest at the absorption maximum of nitrosamines, approximately 340 nm. The plots of NO formation and mutation frequency align with the absorption curve of NPYR, NMOR and NDMA. A significant linear correlation between the optical density of N-dialkynitrosamines at 340 nm and NO formation in each irradiated solution was revealed by ANOVA. We would like to propose the hypothesis that the N-nitroso moiety of N-dialkylnitrosamines absorbs UVA photons, UVA-photolysis of N-dialkylnitrosamines brings release of nitric oxide, and subsequent production of alkyl radical cations and active oxygen species follow as secondary events, which cause DNA strand breaks, oxidative and alkylative DNA damages and mutation.

Gene-Environment Interaction: A Genetic-Epidemiological Approach

Classical epidemiology addresses the distribution and determinants of diseases in populations, and the factors associated with disease causation, with the aim of preventing disease. Both genetic and environmental factors may contribute to susceptibility, and it is still unclear how these factors interact in their influence on risk. Genetic epidemiology is the field which incorporates concepts and methods from different disciplines including epidemiology, genetics, biostatistics, clinical and molecular medicine, and their interaction is crucial to understanding the role of genetic and environmental factors in disease processes. The study of gene-environment interaction is central in the field of genetic epidemiology. Gene-environment interaction is defined as »a different effect of an environmental exposure on disease risk in persons with different genotypes,« or, alternatively, »a different effect of a genotype on disease risk in persons with different environmental exposures.« Five biologically plausible models are described for the relations between genotypes and environmental exposures, in terms of their effects on disease risk. Therefore, the study of gene-environment interaction is important for improving accuracy and precision in the assessment of both genetic and environmental factors, especially in disorders of less defined etiology. Genetic epidemiology is also applied at the various levels of disease prevention.

Epidemiological study of risk factors for esophageal cancer in Yangquan Area of Shanxi Province based on discordant sib pairs

AIM: To explore the main environmental risk factors for esophageal squamous cell carcinoma (ESCC) based on discordant sib pairs (DSPs) in a moderately high-incidence area, Yangquan City, Shanxi Province, and to provide theoretical evidence for developing effective control and prevention measures in this area.

METHODS: A 1:1 matched case-control study was carried out. One hundred and twenty-seven DSPs were recruited from the cancer registration and follow-up system of the local hospital. All ESCC cases and their matched unaffected sibs were subjected to a survey to obtain demographic information along with personal and family history, and lifestyle factors. The McNemar test was used for data analysis.

RESULTS: Compared with matched unaffected sibs, low family income (OR = 2.00, 95%CI: 1.14-3.52, P = 0.0143), hot food eating and drinking (OR = 2.56, 95%CI: 1.44-4.57, P = 0.0009) and heavy drinking (P = 0.0027) were risk factors for ESCC in the area. These factors play important roles in the development of ESCC, even in cases with a family history of ESCC, and the odds ratios (95%CI) were 2.18 (1.07-4.45), 5.00(1.91-13.06) and infinity, respectively.

CONCLUSION: Besides genetic factors, lack of nutrition, hot food eating and heavy drinking are main risk factors for ESCC in Yangquan City. Prevention and control of ESCC should be intervened at multiple levels, such as genetic factors and lifestyles.

Ovarian tumor marker HE4 is differently expressed during the phases of the menstrual cycle in healthy young women

The objective of the present study was to investigate in healthy young women the fluctuations in serum concentration of human epididymal secretory protein human epididymis-specific protein 4 (HE4) and CA125 during the phases of the menstrual cycle and the correlation between HE4 and CA125 values and age. Forty women with regular menstrual cycles were included in the study. Pelvic and transvaginal ultrasound were performed in order to exclude ovarian pathologies. Blood samples were collected at follicular (FP), ovulatory (OP), and luteal (LP) phases of the hormonal cycle. The values of HE4 (expressed as picomoles per liter) observed were (mean ± SEM) 39.1 ± 1.1 (FP), 45.3 ± 1.19 (OP), and 42.0 ± 1.3 (LP). The difference between FP and OP was statistically significant (p = 0.0002). By contrast, serum CA125 levels (expressed as units per milliliter) were 14.35 ± 0.66 (FP), 13.15 ± 0.54 (OP), and 13.70 ± 0.54 (LP), respectively. The levels of HE4 observed in serum samples of women below 35 years were 37.5 ± 1.28 in the FP, 46.6 ± 1.4 in the OP, and 42.8 ± 1.49 in the LP. In this group, a statistically significant difference was observed in the FP compared with the OP (p < 0.0001), whereas no statistically significant difference was observed during the different hormonal phases in the group of women over 35. In conclusion, the correct interpretation of laboratory data is essential to define a threshold of normality, and for what concerns HE4 levels, the menstrual cycle phase-dependent variability appears indicated in the interpretation of the results.