CYP2E1 Polymorphism, Cigarette Smoking, p53 Expression, and Survival in Non-small Cell Lung Cancer

Chronic Inhalation Exposure to Antimony Trioxide Exacerbates the MAPK Signaling in Alveolar Bronchiolar Carcinomas in B6C3F1/N Mice

Antimony trioxide (AT) is used as a flame retardant in fabrics and plastics. Occupational exposure in miners and smelters is mainly through inhalation and dermal contact. Chronic inhalation exposure to AT particulates in B6C3F1/N mice and Wistar Han rats resulted in increased incidences and tumor multiplicities of alveolar/bronchiolar carcinomas (ABCs). In this study, we demonstrated Kras (43%) and Egfr (46%) hotspot mutations in mouse lung tumors (n = 80) and only Egfr (50%) mutations in rat lung tumors (n = 26). Interestingly, there were no differences in the incidences of these mutations in ABCs from rats and mice at exposure concentrations that did and did not exceed the pulmonary overload threshold. There was increased expression of p44/42 mitogen-activated protein kinase (MAPK) (Erk1/2) protein in ABCs harboring mutations in Kras and/or Egfr, confirming the activation of MAPK signaling. Transcriptomic analysis indicated significant alterations in MAPK signaling such as ephrin receptor signaling and signaling by Rho-family GTPases in AT-exposed ABCs. In addition, there was significant overlap between transcriptomic data from mouse ABCs due to AT exposure and human pulmonary adenocarcinoma data. Collectively, these data suggest chronic AT exposure exacerbates MAPK signaling in ABCs and, thus, may be translationally relevant to human lung cancers.

Lung cancer survival and deletion of GSTM1 and GSTT1 genes. A case-series from Spain

Aims and background

Lung cancer has a high incidence, and only 15% of all cases are alive 5 years after the diagnosis. Identifying the role of the genes implicated in the success of chemotherapy agents is crucial to predict survival. The objective of the study was to assess the effect of GSTM1 and GSTT1 gene deletion on lung cancer survival.

Methods and study design

A consecutive sampling of lung cancer cases was performed in 1999–2000 at the University Hospital of Santiago de Compostela, Spain, and GSTM1 and GSTT1 genes were genotyped. The effect of GSTM1 and GSTT1 deletion on survival was analyzed with the logrank test and with Cox regression.

Results

A total of 132 individuals were included, and more than half of them had stage IV lung cancer at diagnosis. Survival was similar irrespective of the presence or absence of the GSTM1 gene, whereas those with deleted GSTT1 had a significantly shorter survival. In multivariate Cox regression analysis, no significant effect was observed for the deletion of any of the genes, although there was a tendency towards a worse survival for those with deletion of GSTT1. The main limitation was that stage at diagnosis could not be considered in the analysis since most of the patients were diagnosed at stage IV.

Conclusions

GSTT1 appears to influence lung cancer survival whereas GSTM1 seems to have no effect.

Cytochrome P-450 Polymorphisms and Clinical Outcome in Patients with Non-Small Cell Lung Cancer

Lung cancer is an increasing worldwide public health problem. Most patients with lung cancer have non-small cell lung cancer (NSCLC). These patients are mainly treated with standard platinum-based chemotherapy. Poor response and great inter-individual variety in treatment response occurs among these patients. There is accumulating evidence to support the hypothesis that genetic polymorphisms alter the drug response and survival. Cytochrome P450 (CYP) enzymes metabolize antineoplastic drugs and are involved in drug resistance. Polymorphic CYPs have altered enzyme activities and thus they may influence the response to chemotherapy and survival in patients with lung cancer. In the current review, recent findings with respect to the role of mainly CYP1A1, CYP1B1, CYP2D6, CYP2E1 and CYP3A4 gene polymorphisms in response to chemotherapy and survival in patients with NSCLC have been provided, which could be useful for clinicians in the prognosis of these patients who are mainly treated with platinum-based chemotherapy.

Genetics of ancestry-specific risk for relapse in acute lymphoblastic leukemia

The causes of individual relapses in children with acute lymphoblastic leukemia (ALL) remain incompletely understood. We evaluated the contribution of germline genetic factors to relapse in 2225 children treated on Children's Oncology Group trial AALL0232. We identified 302 germline single-nucleotide polymorphisms (SNPs) associated with relapse after adjusting for treatment and ancestry and 715 additional SNPs associated with relapse in an ancestry-specific manner. We tested for replication of these relapse-associated SNPs in external data sets of antileukemic drug pharmacokinetics and pharmacodynamics and an independent clinical cohort. 224 SNPs were associated with rapid drug clearance or drug resistance, and 32 were replicated in the independent cohort. The adverse risk associated with black and Hispanic ancestries was attenuated by addition of the 4 SNPs most strongly associated with relapse in these populations (for blacks: model without SNPs hazard ratio (HR)=2.32, P=2.27 × 10-4, model with SNPs HR=1.07, P=0.79; for Hispanics: model without SNPs HR=1.7, P=8.23 × 10-5, model with SNPs HR=1.31, P=0.065). Relapse SNPs associated with asparaginase resistance or allergy were overrepresented among SNPs associated with relapse in the more asparaginase intensive treatment arm (20/54 in Capizzi-methorexate arm vs 8/54 in high-dose methotrexate arm, P=0.015). Inherited genetic variation contributes to race-specific and treatment-specific relapse risk.

Xenobiotic/drug metabolizing enzyme and TP53 polymorphisms and clinical outcome in advanced nonsmall cell lung cancer patients

BACKGROUND/AIM

The association between polymorphisms of xenobiotic/drug metabolizing enzymes and TP53 and response to chemotherapy and survival of patients with nonsmall cell lung cancer (NSCLC) are limited and inconclusive. In this study, CYP2E1*5B, CYP2E1*6, CYP2E1*7B, GSTO1 (A140D), and TP53 (Arg72Pro) polymorphisms and response to platinum-based chemotherapy and survival in 137 advanced stage NSCLC patients were investigated.

MATERIALS AND METHODS

Genetic polymorphism analyses were determined by polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism (RFLP).

RESULTS

The patients with TP53 Pro/Pro variant were more likely to be resistant to chemotherapy than those with Arg/Arg variants with marginal significance (P = 0.066). We also analyzed these gene variants in combination with CYP1A1 (Ile462Val), CYP1B1 (Asn453Ser), GSTM1, GSTP1 exon 5 (Ile105Val), and GSTP1 exon 6 (Ala114Val) and GSTT1 polymorphic genes that we have previously genotyped in the same patients (Ada et al., Neoplasma, 57, 512-527, 2010). The multivariate analysis revealed that adjusted hazard ratio (HR) of death of the combined variant genotypes of TP53 (Arg72Pro, Pro72Pro) and CYP1A1 (Ile462Val, Val462Val) increased significantly as compared to wild-type genotypes (HR, 6.03; 95% CI, 1.39-26.04, P = 0.016).

CONCLUSION

These results show that combined variant genotypes of TP53 (Arg72Pro, Pro72Pro) and CYP1A1 (Ile/Val, Val/Val) are associated with worsening of survival in NSCLC patients.

Deletion of GSTM1 and GSTT1 genes and lung cancer survival: a systematic review

PURPOSE

The mechanisms of lung carcinogenesis are not fully understood. Not all smokers develop lung cancer, indicating that genetic variations and other environmental factors may play an important role in its development. The human glutathione S-transferases (GSTs) have been associated with an increased risk of lung cancer. Glutathione S-transferases are phase II biotransformation enzymes that play a role in detoxifying a wide range of exogenous agents including carcinogens but also anticarcinogenic drugs.

METHODS

We assessed the effect of allelic deletions in the GSTM1 and GSTT1 genotypes on lung cancer overall survival through a systematic review of the scientific literature after applying predefined inclusion and exclusion criteria.

RESULTS

Most of the included studies found no effect or a tendency to worse survival for individuals with deletion of GSTs.

CONCLUSIONS

Further studies are necessary to understand the magnitude of the effect of the deletion of both genes on lung cancer survival.

Effect of smoking on survival from non-small cell lung cancer: a retrospective Veterans' Affairs Central Cancer Registry (VACCR) cohort analysis

Although a well-established risk factor for lung cancer, the impact of smoking on the survival of non-small cell lung cancer (NSCLC) is not well known. We performed a retrospective analysis of the Veteran's Affairs Comprehensive Cancer Registry of NSCLC patients. Smoking status was categorized as never smoker, past smoker and current smoker based on self-reported history. Multivariate analysis was performed to evaluate the impact of smoking on overall survival (OS) from NSCLC. The study population (n = 61,440) comprised predominantly of males (98 %) and Caucasians (81 %). The median age at diagnosis was 68 years (range 22-108 years). Current smokers were diagnosed with NSCLC at a younger age (65 years) compared to never smokers (71 years) and past smokers (72 years) (p < 0.001). On multivariate analysis, current smokers (n = 34,613) [Hazard ratio (HR) 1.059; 95 % confidence interval (CI) 1.012-1.108], but not past smokers (n = 23,864) (HR 1.008; 95 % CI 0.962-1.056), had worse OS for Stage III and IV NSCLC, compared to never smokers (n = 2,963). Smoking status was not prognostic in stages I and II NSCLC. Current smokers were diagnosed with NSCLC at a younger age than never smokers. Although current smoking was associated with worse prognosis, especially in stages III and IV, the impact of smoking status on OS was modest.

Effects of polymorphisms in alcohol metabolism and oxidative stress genes on survival from head and neck cancer

BACKGROUND

Heavy alcohol consumption increases risk of developing squamous cell carcinoma of the head and neck (SCCHN). Alcohol metabolism to cytotoxic and mutagenic intermediates acetaldehyde and reactive oxygen species is critical for alcohol-drinking-associated carcinogenesis. We hypothesized that polymorphisms in alcohol metabolism-related and antioxidant genes influence SCCHN survival.

METHODS

Interview and genotyping data (64 polymorphisms in 12 genes) were obtained from 1227 white and African-American cases from the Carolina Head and Neck Cancer Epidemiology study, a population-based case-control study of SCCHN conducted in North Carolina from 2002 to 2006. Vital status, date and cause of death through 2009 were obtained from the National Death Index. Kaplan-Meier log-rank tests and adjusted hazard ratios were calculated to identify alleles associated with survival.

RESULTS

Most tested SNPs were not associated with survival, with the exception of the minor alleles of rs3813865 and rs8192772 in CYP2E1. These were associated with poorer cancer-specific survival (HRrs3813865, 95% CI=2.00, 1.33-3.01; HRrs8192772, 95% CI=1.62, 1.17-2.23). Hazard ratios for 8 additional SNPs in CYP2E1, GPx2, SOD1, and SOD2, though not statistically significant, were suggestive of differences in allele hazards for all-cause and/or cancer death. No consistent associations with survival were found for SNPs in ADH1B, ADH1C, ADH4, ADH7, ALDH2, GPx2, GPx4, and CAT.

CONCLUSIONS

We identified some polymorphisms in alcohol and oxidative stress metabolism genes that influence survival in subjects with SCCHN. Previously unreported associations of SNPs in CYP2E1 warrant further investigation.

Synergistic association of PTGS2 and CYP2E1 genetic polymorphisms with lung cancer risk in northeastern Chinese

BACKGROUND

Lung cancer is the most common cause of cancer-related deaths worldwide. The aim of this study was to investigate the association of five extensively-studied polymorphisms in PTGS2 (rs689466, rs5275, rs20417) and CYP2E1 (rs2031920, rs6413432) genes with lung cancer risk in a large northeastern Chinese population.

METHODOLOGY/PRINCIPAL FINDINGS

This is a hospital-based case-control study involving 684 patients with lung cancer and 604 cancer-free controls. Genotyping was performed using the PCR-LDR method. Data were analyzed using Haplo.stats and MDR programs. There were significant differences between patients and controls in allele/genotype distributions of rs5275 (P = 0.002/0.003) and rs6413432 (P = 0.037/0.044), as well as in genotype distributions of rs689466 (P = 0.02). The risk for lung cancer associated with the rs5275-C mutant allele was decreased by 60% (95% CI [confidence interval]: 0.21-0.74; P = 0.004) under the recessive model. Carriers of rs689466-G mutant allele had a 28% (95% CI: 0.57-0.92; P = 0.008) reduced risk of developing lung cancer relative to the AA genotype carriers. In haplotype analysis, haplotype G-C-C-T (in order of rs689466, rs5275, rs2031920 and rs6413432) decreased the odds of lung cancer by 28% (95% CI: 0.51-0.93; P = 0.019) after adjusting for confounding factors, whereas haplotype A-T-T-T had 1.49-fold (95% CI: 1.21-1.79; P = 0.012) increased risk for lung cancer. Using MDR method, the overall best model including rs5275, rs689466 and rs6413432 polymorphisms was identified with a maximal testing accuracy of 66.1% and a maximal cross-validation consistency of 10 out of 10 (P = 0.003).

CONCLUSIONS/SIGNIFICANCE

Our findings demonstrated a potentially synergistic association of PTGS2 and CYP2E1 polymorphisms with the underlying cause of lung cancer in northeastern Chinese.

Functional PstI/RsaI polymorphism in CYP2E1 is associated with the development, progression and poor outcome of gastric cancer

BACKGROUND

Cytochrome P450 2E1 (CYP2E1), an ethanol-inducible enzyme, has been shown to metabolically activate various carcinogens, which is critical for the development and progression of cancers. It has demonstrated that CYP2E1 polymorphisms alter the transcriptional activity of the gene. However, studies on the association between CYP2E1 polymorphisms (PstI/RsaI or DraI) and gastric cancer have reported conflicting results. Thus, the aim of the present study was to investigate whether CYP2E1 polymorphisms is associated with the development and progression of gastric cancer and its prognosis in Chinese patients.

METHODS

A case-control study was conducted in which CYP2E1 PstI/RsaI and DraI polymorphisms were analyzed in 510 Chinese patients with gastric cancer and 510 age- and sex- matched healthy controls by PCR-RFLP. Odds ratios were estimated by multivariate logistic regression, and the lifetime was calculated by Kaplan-Meier survival curves. In addition, a meta-analysis was also conducted to verify the findings.

RESULTS

For CYP2E1 PstI/RsaI polymorphism, C2C2 homozygotes (OR = 2.15; CI: 1.18-3.94) and C2 carriers (OR = 1.48; CI: 1.13-1.96) were associated with an increased risk of gastric cancer when compared with C1C1 homozygotes. Both C1C2 and C2C2 genotypes were associated with advanced stage, but not the grade of gastric cancer. Moreover, C2C2 genotype was identified as an independent marker of poor overall survival for gastric cancer. However, there was not any significant association between CYP2E1 DraI polymorphism and the risk of gastric cancer. In the meta-analysis, pooled data from 13 studies confirmed that the CYP2E1 PstI/RsaI polymorphism was associated with a significantly increased risk of gastric cancer.

CONCLUSION

CYP2E1 PstI/RsaI polymorphism is associated with increased risk of development, progression and poor prognosis of gastric cancer in Chinese patients. Pooled data from 13 studies, mainly in Asian countries, are in agreement with our findings.

Pharmacogenetic and germline prognostic markers of lung cancer

INTRODUCTION

Lung cancer is the leading global cause of cancer-related mortality. Interindividual variability in treatment response and cancer outcomes has focused attention on genetic polymorphisms as prognostic markers. We evaluated the overall contribution of candidate polymorphism association studies to our current understanding of the genetic predictors of lung cancer outcomes.

METHODS

We examined the results of 90 studies that evaluated associations between genetic polymorphisms and lung cancer outcomes published between January 1990 and May 2009.

RESULTS

A total of 170 genetic variations in 90 studies were identified. Overall survival was a primary outcome in 81% of the studies and toxicity in 19%. Candidate polymorphisms in the DNA repair/synthesis pathway were the most frequently studied. Strong evidence in large-scale confirmatory studies of any single polymorphism was lacking. Polymorphisms of EGFR, XRCC1, and ERCC1 were associated with pharmacogenetic outcomes, whereas polymorphisms of MDM2, p53, and GSTM1 were associated with prognostic outcomes. All remaining polymorphisms had results lacking or failing replication testing. Heterogeneity in study populations, incomplete reporting of important population or study characteristics, inadequate power, and inconsistencies in methodology were common.

CONCLUSIONS

Although the quality of existing studies involving the candidate polymorphism approach is highly variable, a small set of candidate polymorphisms was identified as potential biomarkers of clinical or pharmacogenetic outcome and would benefit from further replication testing. Newer approaches including haplotype tagging, pathway, genome-wide association, and combination methods with validative approaches may facilitate a more accurate prediction of lung cancer outcomes by genetic variation.

Translational medicine and reliability of single-nucleotide polymorphism studies: can we believe in SNP reports or not?

BACKGROUND

The number of genetic association studies is increasing exponentially. Nonetheless, genetic association reports are prone to potential biases which may influence the reported outcome.

AIM

We hypothesized that positive outcome for a determined polymorphism might be over-reported across genetic association studies analysing a small number of polymorphisms, when compared to studies analysing the same polymorphism together with a high number of other polymorphisms.

METHODS

We systematically reviewed published reports on the association of glutathione s-transferase (GST) single-nucleotide polymorphisms (SNPs) and cancer outcome.

RESULT

We identified 79 eligible trials. Most of the studies examined the GSTM1, theGSTP1 Ile105Val mutation, and GSTT1polymorphisms (n = 54, 57 and 46, respectively). Studies analysing one to three polymorphisms (n = 39) were significantly more likely to present positive outcomes, compared to studies examining more than 3 polymorphisms (n=40) p = 0.004; this was particularly evident for studies analysing the GSTM1polymorphism (p =0.001). We found no significant associations between journal impact factor, number of citations, and probability of publishing positive studies or studies with 1-3 polymorphisms examined.

CONCLUSIONS

We propose a new subtype of publication bias in genetic association studies. Positive results for genetic association studies analysing a small number of polymorphisms (n = 1-3) should be evaluated extremely cautiously, because a very large number of such studies are inconclusive and statistically under-powered. Indeed, publication of misleading reports may affect harmfully medical decision-making and use of resources, both in clinical and pharmacological development setting.

Metabolism and toxicity of styrene in microsomal epoxide hydrolase-deficient mice

Styrene, which is widely used in manufacturing, is both acutely and chronically toxic to mice. Styrene is metabolized by cytochromes P-450 to the toxic metabolite styrene oxide, which is detoxified via hydrolysis with microsomal epoxide hydrolase (mEH) playing a major role. The purpose of these studies was to characterize the importance of this pathway by determining the hepatotoxicity and pneumotoxicity of styrene in wild-type and mEH-deficient (mEH(-/-)) mice. While the mEH(-/-) mice metabolized styrene to styrene oxide at the same rate as the wild-type mice, as expected there was minimal metabolism of styrene oxide to glycol. mEH(-/-) mice were more susceptible to the lethal effects of styrene. Twenty-four hours following the administration of 200 mg/kg ip styrene, mice demonstrated a greater hepatotoxic response due to styrene, as measured by increased serum sorbitol dehydrogenase activity and greater pneumotoxicity as shown by increased protein levels, cell numbers, and lactate dehydrogenase activity in bronchioalveolar lavage fluid. mEH(-/-) mice were also more susceptible to styrene-induced oxidative stress, as indicated by greater decreases in hepatic glutathione levels 3 h after styrene. Styrene oxide at a dose of 150 mg/kg did not produce hepatotoxicity in either wild-type or mEH(-/-) mice. However, styrene oxide produced pneumotoxicity that was similar in the two strains. Thus, mEH plays an important role in the detoxification of styrene but not for exogenously administered styrene oxide.

Differences in epidemiology, histology, and survival between cigarette smokers and never-smokers who develop non-small cell lung cancer

BACKGROUND

The impact that smoking cigarettes has on the characteristics and survival of patients with non-small cell lung cancer (NSCLC) is disputed.

METHODS

A retrospective cohort study using a prospective database of patients with NSCLC over a 6-year period. Clinical and histologic characteristics and survival rates were compared between smokers and never-smokers.

RESULTS

There were 730 patients; 562 patients (77%) were smokers and 168 patients (23%) were never-smokers. The overall 5-year survival rate was greater in never-smokers (64%) compared to smokers (56%; p = 0.031). Never-smokers were more likely to be younger (p = 0.04), female (p = 0.01), symptomatic at the time of presentation (p < 0.001), have poorly differentiated tumors (p = 0.04), and have a higher maximum standardized uptake value (maxSUV) on positron emission tomography (PET) (p = 0.026) than smokers. The stage-specific 5-year survival rate was greater for never-smokers compared to smokers for stage I disease (62% vs 75%, respectively; p = 0.02), stage II disease (46% vs 53%, respectively; p = 0.09), and stage III disease (36% vs 41%, respectively; p = 0.13). The 5-year survival rate was significantly lower in patients who had a smoking history of > 20 pack-years.

CONCLUSIONS

Never-smokers in whom NSCLC develops are more likely to be young, female, and have poorly differentiated tumors with higher maxSUV values on PET scans. Never-smokers with early-stage cancer have a significantly better survival rate than smokers. Patients with a smoking history of > or = 20 pack-years have worse survival. Thus, smoking not only causes lung cancer, but once NSCLC is diagnosed, the prognosis becomes worse. A biological, hormonal, and genetic explanation is currently lacking to explain these findings, and these data may help to improve treatment and surveillance.

Activation of the hedgehog pathway in a subset of lung cancers

Activation of the hedgehog pathway is reported in lung cancer, but its frequency remains unknown. We examine activation of this pathway in lung cancers by in situ hybridization and immunohistochemstry, and find that less than 10% of the tumors have elevated hedgehog target gene expression. We further identify a cell line NCI-H209 and two primary tumors with no detectable Su(Fu), a negative regulator of the pathway. Ectopic expression of Su(Fu) in NCI-H209 cells down-regulates hedgehog target gene expression and leads to inhibition of cell proliferation. These data indicate that activation of the hedgehog pathway is activated through Shh over-expression or Su(Fu) inactivation in only a subset of lung cancers.