Toxicity, Half-Life and Antitumor Activity of Phenyl 4-(2-Oxo-3-alkylimidazolidin-1-yl)benzenesulfonates as Novel Antimitotic CYP1A1-Targeted Prodrugs in Female Mouse Models

Background/Objectives: Chemoresistance of breast cancers (BCs) is a major impediment to current chemotherapeutics that urges the development of new drugs and new therapeutic approaches. To that end, phenyl 4-(2-oxo-3-alkylimidazolidin-1-yl)benzenesulfonates (PAIB-SOs) were recently prepared to fulfill some of the unmet needs with classic chemotherapeutics. PAIB-SOs are prodrugs bioactivated into potent antimitotics by the cytochrome P450 1A1 (CYP1A1), which is a frequent enzyme in resistant BC cells, but mostly missing in normal cells. Our screening program studies of PAIB-SO chemolibraries selected three prototypical PAIB-SOs as antimitotic prodrugs amenable for studies using BC animal models. Methods: Healthy female CD1® IGS mice were treated with three prototypical PAIB-SOs, namely CEU-835, -934, and -938, for the determination of their toxicity and half-lives. Moreover, MCF7 tumor-bearing CD1-Foxn1nu Nude female mice were treated with the three prototypical PAIB-SOs for the determination of their antitumor activity. Results: Herein, we show that multi-intravenous administrations of CEU-835, -934, and -938 at their maximal solubilities are well tolerated in healthy female CD1® IGS mice, as depicted by the evaluation of distress behaviors, organ necropsy, total blood cell count, and histology. Moreover, the half-life of CEU-835, -934, and -938 administered intravenously in healthy CD1® IGS female mice were 8.1, 23.2, and 21.5 h, respectively. Finally, their intravenous administrations of CEU-934 and -938 decreased MCF7 tumor growth as efficiently as paclitaxel in MCF7 tumor-bearing CD1-Foxn1nu Nude mouse model. Conclusions: overall, our study demonstrated for the first time that pentyl-bearing PAIB-SOs are new CYP1A1-dependent prodrugs efficiently decrease breast cancer tumor growth, and show no side effects at their pharmacological concentration in mouse models.

Peripheral Extracellular Vesicles for Diagnosis and Prognosis of Resectable Lung Cancer: The LUCEx Study Protocol

Background/Objectives: Lung cancer is the primary cause of cancer-related deaths. Most patients are typically diagnosed at advanced stages. Low-dose computed tomography (LDCT) has been proven to reduce lung cancer mortality, but screening programs using LDCT are associated with a high number of false positives and unnecessary thoracotomies. It is therefore imperative that a certain diagnosis is refined, especially in cases of solitary pulmonary nodules that are difficult to technically access for an accurate preoperative diagnosis. Extracellular vesicles (EVs) involved in intercellular communication may be an innovative biomarker for diagnosis and therapeutic strategies in lung cancer, regarding their ability to carry tumor-specific cargo. The aim of the LUCEx study is to determine if extracellular vesicle cargoes from both lung tissue and blood could provide complementary information to screen lung cancer patients and enable personalized follow-up after the surgery. Methods: The LUCEx study is a prospective study aiming to recruit 600 patients with lung cancer and 50 control subjects (false positives) undergoing surgery after diagnostic imaging for suspected pulmonary nodules using computed tomography (CT) scans. These patients will undergo curative surgery at the Department of Thoracic Surgery of the Miguel Servet Hospital in Zaragoza, Spain, and will be followed-up for at least 5 years. At baseline, samples from both tumor distal lung tissue and preoperative peripheral blood will be collected and processed to compare the quantity and content of EVs, particularly their micro-RNA (miRNA) cargo. At the third and fifth years of follow-up, CT scans, functional respiratory tests, and blood extractions will be performed. Discussion: Extracellular vesicles and their miRNA have emerged as promising tools for the diagnosis and prognosis of several diseases, including cancer. The LUCEx study, based on an observational clinical cohort, aims to understand the role of these vesicles and their translational potential as complementary tools for imaging diagnosis and prognosis.

Lung cancer associated with combustion particles and fine particulate matter (PM2.5) - The roles of polycyclic aromatic hydrocarbons (PAHs) and the aryl hydrocarbon receptor (AhR)

Air pollution is the leading cause of lung cancer after tobacco smoking, contributing to 20% of all lung cancer deaths. Increased risk associated with living near trafficked roads, occupational exposure to diesel exhaust, indoor coal combustion and cigarette smoking, suggest that combustion components in ambient fine particulate matter (PM2.5), such as polycyclic aromatic hydrocarbons (PAHs), may be central drivers of lung cancer. Activation of the aryl hydrocarbon receptor (AhR) induces expression of xenobiotic-metabolizing enzymes (XMEs) and increase PAH metabolism, formation of reactive metabolites, oxidative stress, DNA damage and mutagenesis. Lung cancer tissues from smokers and workers exposed to high combustion PM levels contain mutagenic signatures derived from PAHs. However, recent findings suggest that ambient air PM2.5 exposure primarily induces lung cancer development through tumor promotion of cells harboring naturally acquired oncogenic mutations, thus lacking typical PAH-induced mutations. On this background, we discuss the role of AhR and PAHs in lung cancer development caused by air pollution focusing on the tumor promoting properties including metabolism, immune system, cell proliferation and survival, tumor microenvironment, cell-to-cell communication, tumor growth and metastasis. We suggest that the dichotomy in lung cancer patterns observed between smoking and outdoor air PM2.5 represent the two ends of a dose-response continuum of combustion PM exposure, where tumor promotion in the peripheral lung appears to be the driving factor at the relatively low-dose exposures from ambient air PM2.5, whereas genotoxicity in the central airways becomes increasingly more important at the higher combustion PM levels encountered through smoking and occupational exposure.

A review on the genetic polymorphisms and susceptibility of cancer patients in Bangladesh

Cancer is one of the major health burdens worldwide, and genetic polymorphisms in individuals are closely associated with cancer susceptibility. Like in many other developing countries, the risk of cancer is increasing among Bangladeshi population. Genetic polymorphisms in xenobiotic metabolic enzymes (CYP1A1, CYP2A6, CYP3A4, CYP3A5, NAT2, SULT1A), cell cycle regulatory proteins (TP53, HER2, MDM2, miR-218-2, TGFB), cell signaling protein (CDH1), DNA repair proteins (BRCA1, BRCA2, EXO1, RAD51, XRCC2, ECCR1, ERCC4, XPC, ERCC2), and others (HLA-DRB1, INSIG2, GCNT1P5) have been found to be associated with various cancers like cancers of breast, bladder, cervix, colon, lung, prostate, etc. in different studies with Bangladeshi population. In this review article, we have discussed these gene polymorphisms associated with cancers in the Bangladeshi population, and also made a comparison with other ethnic groups. This will probably be helpful in understanding drug effects, drug resistance, and personalized medicine in the population of this region.

Identification of Significant Genes in Lung Cancer of Nonsmoking Women via Bioinformatics Analysis

Background

The aim of this study was to identify potential key genes, proteins, and associated interaction networks for the development of lung cancer in nonsmoking women through a bioinformatics approach.

Methods

We used the GSE19804 dataset, which includes 60 lung cancer and corresponding paracancerous tissue samples from nonsmoking women, to perform the work. The GSE19804 microarray was downloaded from the GEO database and differentially expressed genes were identified using the limma package analysis in R software, with the screening criteria of p value < 0.01 and ∣log₂ fold change (FC) | >2.

Results

A total of 169 DEGs including 130 upregulated genes and 39 downregulated were selected. Gene Ontology and KEGG pathway analysis were performed using the DAVID website, and protein-protein interaction (PPI) networks were constructed and the hub gene module was screened through STING and Cytoscape.

Conclusions

We obtained five key genes such as GREM1, MMP11, SPP1, FOSB, and IL33 which were strongly associated with lung cancer in nonsmoking women, which improved understanding and could serve as new therapeutic targets, but their functionality needs further experimental verification.

The breast cancer susceptibility-related polymorphisms at the TOX3/LOC643714 locus associated with lung cancer risk in a Han Chinese population

It has been well established that besides environmental factors, genetic factors are also associated with lung cancer risk. However, to date, the prior identified genetic variants and loci only explain a small fraction of the familial risk of lung cancer. Hence it is vital to investigate the remaining missing heritability to understand the development and process of lung cancer. In the study, to test our hypothesis that the previously identified breast cancer risk-associated genetic polymorphisms at the TOX3/LOC643714 locus might contribute to lung cancer risk, 16 SNPs at the TOX3/LOC643714 locus were evaluated in a Han Chinese population based on a case-control study. Pearson's chi-square test or Fisher's exact test revealed that rs9933638, rs12443621, and rs3104746 were significantly associated with lung cancer risk (P < 0.001, P < 0.001, and P = 0.005, respectively). Logistic regression analyses displayed that lung cancer risk of individuals with rs9933638(GG+GA) were 1.89 times higher than that of rs9933638AA carriers (OR = 1.893, 95% CI = 1.308-2.741, P = 0.001). Similar findings were manifested for rs12443621 (OR = 1.824, 95% CI = 1.272-2.616, P = 0.001, rs12443621(GG+GA) carriers vs. rs12443621AA carriers) and rs3104746 (OR = 1.665, 95% CI = 1.243-2.230, P = 0.001, rs3104746TT carriers vs. rs3104746(TA+AA) carriers). The study discovered for the first time that three SNPs (rs9933638, rs12443621, and rs3104746) at the TOX3/LOC643714 locus contributed to lung cancer risk, providing new evidences that lung cancer and breast cancer are linked at the molecular and genetic level to a certain extent.

A Novel Tobacco Use Phenotype Suggests the 15q25 and 19q13 Loci May be Differentially Associated With Cigarettes per Day and Tobacco-Related Problems

INTRODUCTION

Tobacco use is associated with variation at the 15q25 gene cluster and the cytochrome P450 (CYP) genes CYP2A6 and CYP2B6. Despite the variety of outcomes associated with these genes, few studies have adopted a data-driven approach to defining tobacco use phenotypes for genetic association analyses. We used factor analysis to generate a tobacco use measure, explored its incremental validity over a simple indicator of tobacco involvement: cigarettes per day (CPD), and tested both phenotypes in a genetic association study.

METHODS

Data were from the University of California, San Francisco Family Alcoholism Study (n = 1942) and a Native American sample (n = 255). Factor analyses employed a broad array of tobacco use variables to establish the candidate phenotype. Subsequently, we conducted tests for association with variants in the nicotinic acetylcholine receptor and CYP genes. We explored associations with CPD and our measure. We then examined whether the variants most strongly associated with our measure remained associated after controlling for CPD.

RESULTS

Analyses identified one factor that captured tobacco-related problems. Variants at 15q25 were significantly associated with CPD after multiple testing correction (rs938682: p = .00002, rs1051730: p = .0003, rs16969968: p = .0003). No significant associations were obtained with the tobacco use phenotype; however, suggestive associations were observed for variants in CYP2B6 near CYP2A6 (rs45482602: ps = .0082, .0075) and CYP4Z2P (rs10749865: ps = .0098, .0079).

CONCLUSIONS

CPD captures variation at 15q25. Although strong conclusions cannot be drawn, these finding suggest measuring additional dimensions of problems may detect genetic variation not accounted for by smoking quantity. Replication in independent samples will help further refine phenotype definition efforts.

IMPLICATIONS

Different facets of tobacco-related problems may index unique genetic risk. CPD, a simple measure of tobacco consumption, is associated with variants at the 15q25 gene cluster. Additional dimensions of tobacco problems may help to capture variation at 19q13. Results demonstrate the utility of adopting a data-driven approach to defining phenotypes for genetic association studies of tobacco involvement and provide results that can inform replication efforts.

CYP1A1 MspI Polymorphism and Cervical Carcinoma Risk in the Multi-Ethnic Population of Malaysia: a Case-Control Study

BACKGROUND

Tobacco smoking is considered a risk factor for cervical cancer development due to the presence of tobacco based carcinogenic metabolites in cervical cells of female smokers. In this study, we investigated the role of the T3801C (MspI) polymorphism of CYP1A1, a gene encoding an enzyme necessary for the initiation of tobacco based carcinogen metabolism, on cervical cancer risk. The T to C substitution may alter CYP1A1 activities, potentially elevating cervical cancer risk. Since results of gene-disease association studies vary according to the study population, the multi-ethnic population of Malaysia provides an excellent representative cohort for identifying and comparing the cervical cancer risk among the 3 major ethnics in Southeast Asia in relation to CYP1A1 MspI polymorphism.

MATERIALS AND METHODS

A total of 195 Thin Prep Pap smear samples from HPV negative and cancer free females were randomly selected as controls while 106 formalin fixed paraffin embedded samples from females with invasive cervical cancer were randomly selected for the cases group. The polymorphisms were identified using restriction fragment length polymorphism (RFLP) PCR.

RESULTS

We found no significant associations between CYP1A1 MspI polymorphism and cervical cancer in the general Malaysian female population. However, upon ethnic stratification, the variant C/C genotype was significantly associated with a 4.66-fold increase in cervical cancer risk in Malay females (95% CI= 1.21-17.9; p=0.03). No significant association was observed in the Chinese and Indian females. Additionally, there were no significant associations in the dominant model and allele frequency model analysis in both the general and ethnically stratified female population of Malaysia.

CONCLUSIONS

Our findings suggest that the C/C genotype of CYP1A1 MspI polymorphism is associated with the development of cervical carcinoma in the Malay females of Malaysia.

The interaction between smoking and CYP1A1 MspI polymorphism on lung cancer: a meta-analysis in the Chinese population

Many studies have examined the interaction between CYP1A1 MspI gene polymorphism and smoking for the risk of lung cancer risk in Chinese, but their results have been inconsistent. Therefore, a meta-analysis was performed to ascertain this issue. PubMed, Springer Link, Ovid and other Chinese databases were searched to include all the relevant studies. Smoking status was categorised as 'smokers' and 'non-smokers.' The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using fixed or random effect model. Subgroup analyses according to ethnicity, source of control and geographical location were also conducted. This meta-analysis identified 13 studies containing 2248 lung cases and 3079 controls. Overall, a significant association between lung cancer and the variants of CYP1A1 MspI was found among smokers (type B and type C combined vs. type A: OR = 1.89, 95% CI = 1.15-3.11, P = 0.000 for heterogeneity), whereas not found among non-smokers. Similar to the overall results, stratified analyses showed that the increased risk of lung cancer was observed in population-based studies and north China among smokers (OR = 1.65, 95%CI = 1.03-2.66; OR = 2.00, 95% CI = 1.14-3.53). Our meta-analysis showed that there was an interaction between the CYP1A1 MspI and smoking on the risk of lung cancer in the Chinese population.

Gene-environment interactions in esophageal cancer

Esophageal cancer (EC) is one of the most common malignancies in low- and medium-income countries and represents a disease of public health importance because of its poor prognosis and high mortality rate in these regions. The striking variation in the prevalence of EC among different ethnic groups suggests a significant contribution of population-specific environmental and dietary factors to susceptibility to the disease. Although individuals within a demarcated geographical area are exposed to the same environment and share similar dietary habits, not all of them will develop the disease; thus genetic susceptibility to environmental risk factors may play a key role in the development of EC. A wide range of xenobiotic-metabolizing enzymes are responsible for the metabolism of carcinogens introduced via the diet or inhaled from the environment. Such dietary or environmental carcinogens can bind to DNA, resulting in mutations that may lead to carcinogenesis. Genes involved in the biosynthesis of these enzymes are all subject to genetic polymorphisms that can lead to altered expression or activity of the encoded proteins. Genetic polymorphisms may, therefore, act as molecular biomarkers that can provide important predictive information about carcinogenesis. The aim of this review is to discuss our current knowledge on the genetic risk factors associated with the development of EC in different populations; it addresses mainly the topics of genetic polymorphisms, gene-environment interactions, and carcinogenesis. We have reviewed the published data on genetic polymorphisms of enzymes involved in the metabolism of xenobiotics and discuss some of the potential gene-environment interactions underlying esophageal carcinogenesis. The main enzymes discussed in this review are the glutathione S-transferases (GSTs), N-acetyltransferases (NATs), cytochrome P450s (CYPs), sulfotransferases (SULTs), UDP-glucuronosyltransferases (UGTs), and epoxide hydrolases (EHs), all of which have key roles in the detoxification of environmental and dietary carcinogens. Finally, we discuss recent advances in the study of genetic polymorphisms associated with EC risk, specifically with regard to genome-wide association studies, and examine possible challenges of case-control studies that need to be addressed to better understand the interaction between genetic and environmental factors in esophageal carcinogenesis.

Cytochrome P450 1A1 exon 7 polymorphism and susceptibility to lung cancer in the Chinese population: an updated meta-analysis and review

BACKGROUND

Although many epidemiologic studies have investigated the cytochrome P450 1A1 (CYP1A1) exon 7 gene polymorphism and its association with lung cancer (LC), definitive conclusions cannot be drawn.

OBJECTIVE

To clarify the effects of CYP1A1 exon 7 polymorphism on the risk of LC, an updated meta-analysis was performed in the Chinese population.

METHODS

Related studies were identified from PubMed, Springer Link, Ovid, the Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure (CNKI), and the Chinese Biology Medicine (CBM) databases until October 2014. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the associations.

RESULTS

A total of 25 articles including 3,540 LC cases and 5,284 controls were included in this meta-analysis. Overall, significant association was found between CYP1A1 exon 7 polymorphism and LC risk when all studies in the Chinese population were pooled into this meta-analysis (GG versus AA: OR = 1.71, 95% CI: 1.46-2.01; GG versus AG: OR = 1.41, 95% CI: 1.21-1.64; GG + AG versus AA: OR = 1.37, 95% CI: 1.16-1.62; GG versus AA + AG: OR = 1.52, 95% CI: 1.32-1.76). In subgroup analyses stratified by ethnicity, source of controls, and geographical locations, significantly increased risk was found in Chinese Han people, in population-based studies, in hospital-based studies, in South China, and in North China.

CONCLUSION

This meta-analysis provides the evidence that CYP1A1 exon 7 polymorphism may contribute to LC development in the Chinese population, and studies with a larger sample size and wider population spectrum are warranted to verify this finding.

Genetic polymorphisms of phase I and phase II metabolic enzymes as modulators of lung cancer susceptibility

OBJECTIVES

Tobacco exposure remains the main etiologic factor for lung cancer (LC). Interactions between environment and individual genetic profile are particularly important for this disease. The aim of this study was to evaluate the contribution of CYP1A1*2A, CYP1A1*2C, CYP2D6*4, GSTP1, GSTM1, GSTT1 and NAT2 polymorphisms for the susceptibility to LC in a Portuguese population considering their demographic and clinical characteristics.

MATERIALS AND METHODS

A total of 200 LC and 247 controls subjects from the Centre of Portugal were studied. Clinical and demographic characteristics were collected from clinical files and by individual questionnaires. Polymorphisms of CYP1A1*2A, CYP1A1*2C, CYP2D6*4, GSTP1, GSTM1, GSTT1 and NAT2 were genotyped using PCR-RFLP, PCR multiplex, ARMS and real time.

RESULTS

Gender, family history of cancer, smoke cessation and alcohol consumption were independent risk factors (p < 0.05). Associations found between phases I and II genes and LC population reveal a sex dependent distribution. Logistic regression analysis demonstrates that enhanced activation by CYPs, associated by reduced or loss of function of phase II enzymes, can lead to a greater risk. GSTP1 and NAT2 polymorphisms studied have a significant contribution for the histological tumour types and the presence of metastases, at time of diagnosis, respectively, when males with smoking habits were considered.

CONCLUSION

Multiple interactions between environment and individual characteristics are clearly associated to this disease. Variants of the detoxification genes may act synergistically contributing to this disease and modifying the risk posed by smoking and sex. The GSTT1*0 and GSTP1 (Ile462Val) might contribute to the malignant phenotype through different mechanisms.

Common genetic variants on 3q28 contribute to non-small cell lung cancer susceptibility: evidence from 10 case-control studies

The association between common variations (rs10937405, rs4488809) on 3q28 and lung cancer has been widely evaluated in various ethnic groups, since it was first identified through genome-wide association approach. However, the results have been inconclusive. To derive a more precise estimation of the relationship and the effect of factors that might modify the risk, we performed this meta-analysis. The random-effects model was applied, addressing heterogeneity and publication bias. A total of 10 articles involving 36,221 cases and 58,108 controls were included. Overall, the summary per-allele OR of 1.19 (95 % CI 1.14-1.25, P < 10(-5)) and 1.17 (95 % CI 1.10-1.23, P < 10(-5)) was found for the rs10937405 and rs4488809 polymorphisms, respectively. Significant results were also observed in heterozygous and homozygous when compared with wild genotype for these polymorphisms. Significant results were found in East Asians when stratified by ethnicity, whereas no significant associations were found among Caucasians. After stratifying by sample size, study design, control source and sex, significant associations were also obtained. In addition, our data indicate that these polymorphisms are involved in lung cancer susceptibility and confer its effect primarily in lung adenocarcinoma when stratified by histological subtype. Furthermore, significant associations were also detected both never-smokers and smokers for these polymorphisms. In conclusion, this meta-analysis demonstrated that rs10937405 and rs4488809 are a risk factor associated with increased non-small cell lung cancer susceptibility, particularly for East Asian populations.

CYP1A1 polymorphism interactions with smoking status in oral cancer risk: evidence from epidemiological studies

The cytochrome CYP1A1 gene has been implicated in the etiology of oral cancer. However, the results have been inconsistent. In this study, a meta-analysis was performed to clarify the associations of polymorphisms in CYP1A1 gene with oral cancer risk. Published literatures from PubMed, MEDLINE, EMBASE, and China National Knowledge infrastructure (CNKI) databases were retrieved. A total of 12 studies were included in this meta-analysis. We found that significant positive associations between CYP1A1*2A polymorphism and oral cancer risk in recessive model (CC vs. TC + TT, OR = 1.93), dominant model (CC + TC vs. TT, OR = 1.33), and additive model (CC vs. TT, OR = 1.97). In subgroup analysis based on the ethnicity of study population, significant associations were found in all three genetic models for Asians (recessive OR = 2.29, 95% CI =  .42-3.71; dominant OR = 1.54, 95% CI = 1.03-2.31; additive OR  2.39, 95% CI = 1.47-3.88) but not non-Asians. For the smoking stratification, the result indicated a significant association between CYP1A1*2A polymorphism and oral cancer among the smoking subjects (OR = 1.83, 95% CI = 1.47-2.26). This meta-analysis indicated a marked association of CYP1A1*2A polymorphisms with oral cancer risk, particularly among Asians, whereas there were significant interactions between the polymorphisms and cigarette smoking on oral cancer risk.

Cytochrome P450 2A6 deletion polymorphism and risk of lung cancer: a meta-analysis

Previous studies concerning the association between cytochrome P450 2A6 (CYP2A6) deletion polymorphism and lung cancer risk provided controversial results. To clarify the precise association, a meta-analysis was performed. The electronic databases PubMed, Chinese Biomedical Database and Chinese National Knowledge Infrastructure Database were searched for case-control studies last updated on June 3, 2012 that investigated CYP2A6 deletion polymorphism and lung cancer risk. The odds ratio (OR) and its respective 95 % confidence interval (95 % CI) were used to measure the strength of association by means of a genetic model free approach. A total of 8 studies including 2,607 cases and 2,595 controls met the inclusion criteria and were subjected to the final analysis. The most appropriate co-dominant model was adopted. Overall, we found that CYP2A6 *1/*1 genotype was associated with an increased risk of lung cancer relative to *4/*4 genotype (OR = 2.65, 95 % CI: 1.84-3.81, P < 0.001). Significant association was also detected among Asians. Publication bias was absent in this meta-analysis. Therefore, our data suggested that the presence of the CYP2A6 *1/*1 might be associated with an increased lung cancer risk, especially for Asians. Further studies well-designed among different ethnicity populations are required.

Genetic susceptibility to lung cancer--light at the end of the tunnel?

Lung cancer is one of the most common and deadliest cancers in the world. The major socio-environmental risk factor involved in the development of lung cancer is cigarette smoking. Additionally, there are multiple genetic factors, which may also play a role in lung cancer risk. Early work focused on the presence of relatively prevalent but low-penetrance alterations in candidate genes leading to increased risk of lung cancer. Development of new technologies such as genomic profiling and genome-wide association studies has been helpful in the detection of new genetic variants likely involved in lung cancer risk. In this review, we discuss the role of multiple genetic variants and review their putative role in the risk of lung cancer. Identifying genetic biomarkers and patterns of genetic risk may be useful in the earlier detection and treatment of lung cancer patients.

Haplotypes in the 5'-untranslated region of the CYP1A2 gene are inversely associated with lung cancer risk but do not correlate with caffeine metabolism

In this study, we analyzed the influence of CYP1A2 genetic variation and enzyme activity on lung cancer risk in a high-incidence area. A total of 95 lung cancer patients and 196 controls were genotyped for the -3860G/A, -3113A/G, -2467T/delT, -739T/G, and -163C/A polymorphisms in the 5'-untranslated region of the gene. In addition, a subset of 70 patients and 115 controls were phenotyped by high-performance liquid chromatography determination of the caffeine metabolic ratio (CMR). The -2467T/delT polymorphism and the CYP1A2*1V haplotype (-163C>A, -2467T>delT) were inversely associated with lung cancer risk (odds ratio [OR] = 0.47 [0.2-0.9]; P = 0.02 and OR = 0.13 [0.02-1.0]; P = 0.04; respectively). In addition, the CYP*1A/*1V and *1F (-163C>A)/*1D (-163C>A, -2467T>delT) diplotypes were absent in the patients group, whereas accounting for 7.1% (P = 0.017) and 5.6% (P = 0.037) of controls, respectively. Mean CMR was significantly higher in patients than in controls (10.50 ± 17.31 vs. 6.52 ± 6.26, P = 0.01) but regression analyses did not yield significant ORs for the association with lung cancer risk. Similarly, no significant correlations were found between any genetic variant and enzyme activity. Several CYP1A2 haplotypes and diplotypes containing the -2467delT variant were associated with lower lung cancer risk; however, they did not correlate with significant changes in CYP1A2 metabolic activity toward caffeine.

Pharmacogenetic assessment of clinical outcome in patients with metastatic breast cancer treated with docetaxel plus capecitabine

PURPOSE

Docetaxel plus capecitabine, a commonly used chemotherapeutic regimen for metastatic breast cancer (MBC), is highly variable in its effectiveness. We aimed to investigate whether allelic variants of cytochrome P450 (CYP450) affected objective response, progression-free survival (PFS), and overall survival (OS) in MBC.

PATIENTS AND METHODS

79 SNPs in CYP450, whose minor allele frequency were ≥ 10%, were genotyped in 69 MBC patients who were treated with docetaxel plus capecitabine. Pearson's χ(2) test or Fisher's exact test was used to investigate the influence of SNPs on objective response as appropriate. Log-rank test was used to assess the association between SNPs and survival outcomes.

RESULTS

There is no significant association between polymorphisms and both objective response and OS. Only one SNP, CYP1A1 rs1048943 A>G (Ile462Val), was significantly associated with PFS (P = 0.0003). Multivariate analysis confirmed its prognostic significance for PFS (P = 0.004).

CONCLUSION

CYP1A1 rs1048943 A>G (Ile462Val) polymorphism is a potential prognostic marker for survival outcome after docetaxel plus capecitabine chemotherapy in MBC patients. However, confirmatory study is needed to validate this finding.

Meta-analysis of the association of CYP1A1 polymorphisms with gastric cancer susceptibility and interaction with tobacco smoking

The association of two cytochrome P4501A1 (CYP1A1) polymorphisms, m1 (T6235C transition) and m2 (A4889G transition), with gastric cancer risk is inconclusive. We conducted a meta-analysis of all available studies to evaluate the potential role of the polymorphisms and their interactions with tobacco smoking in gastric cancer susceptibility. Published literature from PubMed was retrieved by two investigators independently. Fourteen case-control studies with 2,032 gastric cancer cases and 5,099 controls were selected. A fixed effects model or a random-effects model was used to estimate the odds ratio (OR) for the CYP1A1 polymorphisms and the occurrence of gastric cancer. Significant associations between CYP1A1 m1 and m2 polymorphisms and gastric cancer susceptibility were not observed in all genetic models in the overall analyses. Subgroup analyses by ethnicity and source of controls did not reveal significant associations with gastric cancer risk. Stratification analysis by smoking status found that carriers of the heterozygous and homozygous m1 genotypes decreased the susceptibility of gastric cancer among ever-smokers (pooled OR = 0.56, 95 % CI 0.36-0.89, fixed effects). In contrast, the m2 genotypes (G/G and A/G) did not show any relevance to gastric cancer risk among the smoking population (pooled OR = 1.30, 95 % CI 0.84-2.00, fixed effects). Overall, we found that the CYP1A1 polymorphism itself, either m1 or m2, did not represent an independent genetic risk factor influencing gastric cancer. However, subgroup analyses suggest that carriers of the heterozygous and homozygous m1 genotype who are exposed to tobacco smoke have a significantly lower risk of developing gastric cancer. To explain the observed reduction of gastric cancer risk, we proposed a novel hypothesis of "observation bias". This hypothesis is also applicable to explain the combined effects of other genetic polymorphisms and environmental factors on the risk of developing cancers, and the rationality of the hypothesis needs to be further investigated.

Correlation of CYP1A1, GSTP1 and GSTM1 gene polymorphisms and lung cancer risk among smokers

Lung cancer is the leading cause of cancer mortality worldwide and tobacco smoking has been established as its biggest risk factor. Cigarette smoke contains several carcinogens. Most of them need to be activated by phase I enzymes, such as cytochrome P450 (CYP), while phase II enzymes, such as glutathione S-transferases are responsible for the detoxification of activated forms. The present study aimed to determine the role of CYP1A1, GSTP1 and GSTM1 gene polymorphisms in smoking-related lung cancer risk. It also aimed to investigate the association of the above polymorphisms with clinicopathological parameters, as well as their effect on survival. One hundred newly diagnosed lung cancer patients with advanced disease and 125 healthy controls with a smoking history participated in the study. The participants were screened for the presence of the following polymorphisms: MspI (CYP1A1), Ile105Val (GSTP1) and GSTM1 deletion. The above polymorphisms were also examined with regards to gender, age, histological type and survival. GSTP1 Ile/Val and GSTM1-null genotypes were associated with increased lung cancer risk and the presence of the combination of the three non-wild-type genotypes increases susceptibility to lung cancer (OR 3.328, 95% CI=1.681-6.587, p=0.001). In the non-small cell lung cancer group, the GSTP1 homozygous variant was significantly associated with increased lung cancer risk (p=0.008) and shorter survival. The results of this study suggest that the GSTP1 Ile/Val genotype and GSTM1 deletion contribute to increased lung cancer susceptibility. Moreover, GSTP1 Val/Val genotype is associated with increased lung cancer risk and shorter survival in non-small cell lung cancer patients.

Lung cancer in never smokers--a review

An estimated 10-25% of lung cancers worldwide occur in never smokers, i.e. individuals having smoked less than 100 cigarettes in their lifetime. Lung cancer in never smokers (LCINS) is more frequent in women, although large geographic variations are found. Histologically, adenocarcinomas predominate. The mere existence of LCINS suggests that risk factors other than smoking must be present. Exposure to environmental tobacco smoke (particularly in women) and exposure to workplace carcinogens (particularly in men) are the two most important alternative risk factors. However, a history of either is absent in more than a third of LCINS. The large proportion of women in LCINS suggest a hormonal element that may interact with other identified factors such as hereditary risks, a history of respiratory infections or disease, exposure to air pollution, cooking and heating fumes, or exposure to ionising radiation. The study of genomic polymorphisms finds constitutive DNA variations across subjects according to their smoking status, particularly in genes coding for enzymes that participate in the metabolism of certain carcinogens, in those coding for DNA repair enzymes, or in genes associated with tobacco addiction, or inflammatory processes. The type of molecular mutation in p53 or KRAS varies with smoking status. EGFR mutations are more frequent in never smokers, as are EML4-ALK fusions. The mutually exclusive nature of certain mutations is a strong argument in favour of separate genetic paths to cancer for ever smokers and never smokers. In the present paper we review current clinical and molecular aspects of LCINS.

Association of mitochondrial DNA variations with lung cancer risk in a Han Chinese population from southwestern China

Mitochondrial DNA (mtDNA) is particularly susceptible to oxidative damage and mutation due to the high rate of reactive oxygen species (ROS) production and limited DNA-repair capacity in mitochondrial. Previous studies demonstrated that the increased mtDNA copy number for compensation for damage, which was associated with cigarette smoking, has been found to be associated with lung cancer risk among heavy smokers. Given that the common and “non-pathological” mtDNA variations determine differences in oxidative phosphorylation performance and ROS production, an important determinant of lung cancer risk, we hypothesize that the mtDNA variations may play roles in lung cancer risk. To test this hypothesis, we conducted a case-control study to compare the frequencies of mtDNA haplogroups and an 822 bp mtDNA deletion between 422 lung cancer patients and 504 controls. Multivariate logistic regression analysis revealed that haplogroups D and F were related to individual lung cancer resistance (OR = 0.465, 95%CI = 0.329–0.656, p<0.001; and OR = 0.622, 95%CI = 0.425–0.909, p = 0.014, respectively), while haplogroups G and M7 might be risk factors for lung cancer (OR = 3.924, 95%CI = 1.757–6.689, p<0.001; and OR = 2.037, 95%CI = 1.253–3.312, p = 0.004, respectively). Additionally, multivariate logistic regression analysis revealed that cigarette smoking was a risk factor for the 822 bp mtDNA deletion. Furthermore, the increased frequencies of the mtDNA deletion in male cigarette smoking subjects of combined cases and controls with haplogroup D indicated that the haplogroup D might be susceptible to DNA damage from external ROS caused by heavy cigarette smoking.

Single nucleotide polymorphisms as susceptibility, prognostic, and therapeutic markers of nonsmall cell lung cancer

Lung cancer is a major public health problem throughout the world. Among the most frequent cancer types (prostate, breast, colorectal, stomach, lung), lung cancer is the leading cause of cancer-related deaths worldwide. Among the two major subtypes of small cell lung cancer and nonsmall cell lung cancer (NSCLC), 85% of tumors belong to the NSCLC histological types. Small cell lung cancer is associated with the shortest survival time. Although tobacco smoking has been recognized as the major risk factor for lung cancer, there is a great interindividual and interethnic difference in risk of developing lung cancer given exposure to similar environmental and lifestyle factors. This may indicate that in addition to chemical and environmental factors, genetic variations in the genome may contribute to risk modification. A common type of genetic variation in the genome, known as single nucleotide polymorphism, has been found to be associated with susceptibility to lung cancer. Interestingly, many of these polymorphisms are found in the genes that regulate major pathways of carcinogen metabolism (cytochrome P450 genes), detoxification (glutathione S-transferases), adduct removal (DNA repair genes), cell growth/apoptosis (TP53/MDM2), the immune system (cytokines/chemokines), and membrane receptors (nicotinic acetylcholine and dopaminergic receptors). Some of these polymorphisms have been shown to alter the level of mRNA, and protein structure and function. In addition to being susceptibility markers, several of these polymorphisms are emerging to be important for response to chemotherapy/radiotherapy and survival of patients. Therefore, it is hypothesized that single nucleotide polymorphisms will be valuable genetic markers in individual-based prognosis and therapy in future. Here we will review some of the most important single nucleotide polymorphisms in the metabolic pathways that may modulate susceptibility, prognosis, and therapy in NSCLC.

CYP1A1 MspI and exon7 gene polymorphisms and lung cancer risk: an updated meta-analysis and review

BACKGROUND

Many studies have examined the association between the CYP1A1 MspI and exon 7 gene polymorphisms and lung cancer risk in various populations, but their results have been inconsistent.

METHODS

To assess this relationship more precisely, a meta-analysis and review were performed. The PubMed, Embase, Web of Science, and CNKI database was searched for case-control studies published up to June 2010. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

Ultimately, 64 studies, comprising 18,397 subjects from 49 case-control studies of the MspI genotype and 18,518 patients from 40 case-control studies of the exon 7 genotype, were included. A significantly elevated lung cancer risk was associated with 2 MspI genotype variants (for type C vs. Type A: OR = 1.26, 95% CI = 1.12-1.42; for types B and C combined vs. Type A: OR = 1.20, 95% CI = 1.13-1.28) in overall population. In the stratified analysis, a significant association was found in Asians, Caucasians, lung SCC, lung AC and Male population, not in mixed population, lung SCLC and female population. However, inconsistent results were observed for CYP1A1 exon7 in our meta-analysis, two variants of the exon 7 polymorphism were associated with a significantly higher risk for lung cancer (for Val/Val vs. Ile/Ile: OR = 1.24, 95% CI = 1.09-1.42; for (Ile/Val +Val/Val) vs. Ile/Ile: OR = 1.15, 95% CI = 1.07-1.24) in overall population. In the stratified analysis, a significant assocation was found in Asians, Caucasians, lung SCC and Female population, not in mixed population, lung AD, lung SCLC and Male population. Additionally, a significant association was found in smoker population and not found in non-smoker populations for CYP1A1 MspI and exon7 gene.

CONCLUSIONS

This meta-analysis suggests that the MspI and exon 7 polymorphisms of CYP1A1 correlate with increased lung cancer susceptibility and there is an interaction between two genotypes of CYP1A1 polymorphism and smoking, but these associations vary in different ethnic populations, histological types of lung cancer and gender of case and control population.