CYP and GST polymorphisms and survival in advanced non-small cell lung cancer patients

Genetic polymorphisms as potential pharmacogenetic biomarkers for platinum-based chemotherapy in non-small cell lung cancer

Platinum-based chemotherapy (PBC) is a widely used treatment for various solid tumors, including non-small cell lung cancer (NSCLC). However, its efficacy is often compromised by the emergence of drug resistance in patients. There is growing evidence that genetic variations may influence the susceptibility of NSCLC patients to develop resistance to PBC. Here, we provide a comprehensive overview of the mechanisms underlying platinum drug resistance and highlight the important role that genetic polymorphisms play in this process. This paper discussed the genetic variants that regulate DNA repair, cellular movement, drug transport, metabolic processing, and immune response, with a focus on their effects on response to PBC. The potential applications of these genetic polymorphisms as predictive indicators in clinical practice are explored, as are the challenges associated with their implementation.

Association of CYP1A2 and GST gene variants with asthma in cases presenting with allergic chronic rhinosinusitis

Background

Inter-individual differences in regulation and activity of xenobiotic metabolizing enzymes (XMEs) CYP1A and GST might cause distinct susceptibility to chronic rhinosinusitis (CRS) phenotypes that need to be explored. Therefore, the present study aimed to evaluate the role and risk of CYP1A and GST gene variants in allergic CRS subjects with and without asthma. A total of 224 allergic CRS cases with asthma, 252 allergic CRS cases without asthma, and 350 healthy control subjects were subjected to genetic analysis. Gene variants of cytochrome P450 (CYP1A1 T3801 rs4646903, A2455G rs1048943, C2453A rs1799814 and CYP1A2 G3858A rs2069514, T739G rs2069526, C163A rs762551) and glutathione S-transferase P (GSTP1 A313G rs1605 & C341T rs1799811) were investigated by polymerase chain reaction-restriction fragment length polymorphism and GSTM1null, and GSTT1null by multiplex PCR methods.

Results

TG genotype of CYP1A2 rs2069526 (OR 1.73, 95% CI 1.20–2.50, p < 0.002), TC genotype of CYP1A1 rs4646903 (OR 1.43, 95% CI 1.03–1.98, p < 0.031) and GSTM1del (OR 1.87, 95% CI 1.24–2.81, p < 0.003) and were found to be significantly associated with only allergic CRS cases. CYP1A2 rs2069526 (OR 2.33, 95% CI 1.61–3.37, p < 0.001), GG genotype of GSTP1 rs1605 (OR 4.75, 95% CI 2.62–8.63, p < 0.001), GSTM1del (OR 1.82, 95% CI 1.19–2.78, p < 0.006), GSTM1/GSTT1 double null (OR 2.58, 95% CI 1.36–4.87, p < 0.004) and were found to be significantly associated with asthma in allergic CRS cases. Further, G-G-C haplotype of CYP1A2 rs2069514, rs2069526 and rs762551 gene variants was found to increase the risk for asthma by 5 folds in allergic CRS subjects (OR 5.53, 95% CI 1.76–17.31, p < 0.003) while T-G-C haplotype of CYP1A1 rs4646903, rs1048943, rs1799814 (OR 0.11, 95% CI (0.01–0.95, p < 0.045) and A-T haplotype of GSTP1 rs1605, rs1799811 (OR 0.27, 95% CI (0.08–0.89, p < 0.032) showed protective effect in allergic CRS group.

Conclusion

The present study reports the significantly increased association of CYP1A2, GSTM, and GSTP gene variants with asthma in allergic CRS.

GSTP1 Ile105Val polymorphism among North Indian lung cancer patients treated using monotherapy and poly-pharmacy

BACKGROUND

Genetic polymorphism within the P1 isoenzyme of the Glutathione-S-Transferase (GST) family is found to modulate and alter the enzyme activity of GSTP1 protein and thus may result in a change of sensitivity to platinum-based chemotherapy. We investigated the relationship between GSTP1 Ile105Val polymorphisms and overall survival, treatment response, and for both hematological and non-hematological toxicity of advanced North Indian lung cancer patients undergoing platinum-based double chemotherapy.

METHODS

The polymorphism of GSTP1 Ile105Val in North Indian lung cancer patients was assessed by polymerase chain reaction-restriction fragment length polymorphism. A total of 682 lung cancer patients were enrolled in the study, and it was observed that patients who were carrying both the mutant alleles (Val/Val) for the GSTP1 polymorphism showed a higher trend of median survival time (MST) as compared to the patients bearing the wild type of genotype (Ile/Ile) (MST = 8.30 vs. 7.47, p = 0.56). Based on toxicity profiling, we observed that lung cancer patients with the mutant genotype of GSTP1 (Val/Val) had an increased risk of leukopenia (OR = 2.41; 95% CI = 1.39-4.18, p = 0.001) as compared to subjects carrying both copies of the wild alleles (Ile/Ile). Our data suggested that patients with heterozygous genotype (Ile/Val) had a 2.14-fold increased risk of developing severe anemia (OR = 2.14, 95% CI = 0.97-4.62, p = 0.03). Our data also showed that in small cell lung carcinoma (SCLC) patients' polymorphism of GSTP1 was associated with thrombocytopenia (χ2 test = 7.32, p = 0.02).

CONCLUSIONS

Our results suggest that GSTP1 Ile105Val polymorphism could be a predictive biomarker for hematological toxicity, like leukopenia and anemia, but not thrombocytopenia or neutropenia.

Evaluation of molecular markers GSTM1 and GSTT1 and clinical factors in breast cancer: case-control study and literature review

The study was conducted to evaluate the frequency of polymorphisms in GSTM1 and GSTT1 genes in patients with breast cancer compared with individuals without history of cancer, and the association of these polymorphisms with clinical/epidemiological parameters.There were evaluated 752 women (219 patients and 533 controls). Molecular analysis was performed by the Polymerase Chain Reaction (PCR). Statistical analysis was used multiple logistic regression and descriptive statistics.Age ≥50 years (OR =3.22, 95% CI =2.30 - 4.51, p <0.001) and alcohol consumption (OR =1.60, 95% CI =1.13 - 2.27, p = 0.008) were associated to the development of breast cancer, while smoking and null genotypes GSTM1 and GSTT1 presented no association. GSTM1 and GSTT1 polymorphisms presented no relationship with the clinical and histopathological parameters or molecular subtypes of breast cancer. Ninety-two percent of tumors were invasive ductal, 66% were grade II, 65% were larger than 2 cm, the stages II (35.3%) and III (31.2%) were the most prevalent, and 47.7% were molecular subtype luminal B.Individuals aged ≥50 years and alcohol consumers have more chance to developing breast cancer. GSTM1 and GSTT1 polymorphisms are not associated to the risk of breast cancer.

Genetic polymorphisms of GSTP1, XRCC1, XPC and ERCC1: prediction of clinical outcome of platinum-based chemotherapy in advanced non-small cell lung cancer patients of Bangladesh

Inter-individual genetic makeup can trigger variability in platinum-based chemotherapeutic responses and corresponding adverse drug reactions and toxicities. Exploring the genetic causes behind these inter-individual variabilities in platinum-based chemotherapeutic responses by investigating the effects of GSTP1 (rs1695), XRCC1 (rs25487), XPC (rs2228001) and ERCC1 (rs11615) genetic polymorphisms on toxicity and therapeutic response of this treatment among Bangladeshi advanced non-small cell lung cancer (NSCLC) patients was the aim of this study. 285 Clinically proven either stage IIIB or IV (advanced) NSCLC patients aging not less than 18 years old and receiving platinum-based chemotherapy were recruited to assess the influence of these four single nucleotide polymorphisms (SNPs) on peripheral leukocytes. Toxicity and response were evaluated by multivariate regression analyses using SPSS statistical software (version 17.0). XRCC1 (rs25487) polymorphism was found to act as a predictive factor for not only grade 3 and 4 anemia (p = 0.008), neutropenia (p = 0.010), thrombocytopenia (p = 0.025) and gastrointestinal toxicity (p = 0.002) but also for therapeutic response (p = 0.012) in platinum-based chemotherapy. Although GSTP1 (rs1695) polymorphism might serve as prognostic factor regarding grade 3 or 4 neutropenia, a significant (p = 0.044) improvement in response to platinum-based chemotherapy was observed. However, XPC (rs2228001) and ERCC1 (rs11615) polymorphisms could not establish any significant relation with toxicity or therapeutic response. XRCC1 (rs2228001) and GSTP1 (rs1695) polymorphisms might explain platinum-induced clinical outcomes in terms of both toxicity and therapeutic response variations among Bangladeshi advanced NSCLC patients.

Glutathione Transferase P1-1 an Enzyme Useful in Biomedicine and as Biomarker in Clinical Practice and in Environmental Pollution

Glutathione transferase P1-1 (GSTP1-1) is expressed in some human tissues and is abundant in mammalian erythrocytes (here termed e-GST). This enzyme is able to detoxify the cell from endogenous and exogenous toxic compounds by using glutathione (GSH) or by acting as a ligandin. This review collects studies that propose GSTP1-1 as a useful biomarker in different fields of application. The most relevant studies are focused on GSTP1-1 as a biosensor to detect blood toxicity in patients affected by kidney diseases. In fact, this detoxifying enzyme is over-expressed in erythrocytes when unusual amounts of toxins are present in the body. Here we review articles concerning the level of GST in chronic kidney disease patients, in maintenance hemodialysis patients and to assess dialysis adequacy. GST is also over-expressed in autoimmune disease like scleroderma, and in kidney transplant patients and it may be used to check the efficiency of transplanted kidneys. The involvement of GSTP in the oxidative stress and in other human pathologies like cancer, liver and neurodegenerative diseases, and psychiatric disorders is also reported. Promising applications of e-GST discussed in the present review are its use for monitoring human subjects living in polluted areas and mammals for veterinary purpose.

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.

Polymorphisms and Protein Expressions of Glutathione S-Transferase M1 and T1 in Non-Small Cell Lung Cancer

Objectives

The deletion polymorphisms of glutathione S-transferase (GST) GSTM1 and GSTT1 genes result in the absence of the corresponding protein, which decreases the detoxification of carcinogens. Studies evaluating polymorphisms and protein expressions in the same patients are limited. Therefore, in this study, we aimed to investigate the association between polymorphisms and protein expressions of GSTM1 and GSTT1 in lung tissues of patients with non-small cell lung cancer (NSCLC).

Materials and Methods

For protein expression and gene deletion studies, tumor and surrounding tumor free (normal) tissue of 33 patients with NSCLC were used. In paraffin-embedded tissues, immunohistochemistry was used to detect protein expressions, and multiplex polymerase chain reaction amplification was used to identify gene deletions.

Results

GSTM1 and GSTT1 protein expressions were not detected in patients with GSTM1 and GSTT1 gene deletions, whereas protein expressions were detected in lung tissues of all patients carrying GSTM1 and GSTT1 genes. The protein expression level of GSTT1 was 2.0-fold higher in tumors of patients lacking GSTM1 genes than those with GSTM1 genes (p=0.018). Protein expression of GSTM1 was statistically higher in tumor tissues than in normal tissues of patients with GSTM1 genes (p=0.001).

Conclusion

These results show that a) there is an association between gene deletions and protein expressions of GSTM1 and GSTT1 in patients with NSCLC, b) in the absence of GSTM1 genes, enhancement of expression of GSTT1 in tumors is likely to show that GSTT1 increases its capacity to detoxify the toxic electrophiles in tumors, and c) GSTM1 protein expression is higher in tumors compared with normal lung tissues of patients with NSCLC.

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.

Predictive assessment in pharmacogenetics of Glutathione S-transferases genes on efficacy of platinum-based chemotherapy in non-small cell lung cancer patients

The influences of glutathione s-transferase P1, M1, and T1 variants on the efficacy of platinum-based chemotherapy in non-small cell lung cancer (NSCLC) patients were inconsistent in previous studies. Our meta-analysis enrolled 31 publications including 5712 patients and provided more convincing and reliable conclusions. Results showed that GSTP1 IIe105Val IIe/Val and Val/Val Asian patients were more likely to have better response rates compared to IIe/IIe patients (odds ratio (OR) = 1.592, 95% confidence intervals (CIs), 1.087-2.332, P = 0.017). The Asian patients bearing the favorable GSTM1 null genotype were more likely to have better response rates to platinum-based chemotherapy compared to those patients with the unfavorable GSTM1 present genotype (OR = 1.493 (1.192-1.870), P < 0.001). Caucasian lung cancer patients bearing GSTT1 null genotype might be more closely associated with shorter survival time and higher risks of death than the GSTT1 present patients (hazard ratio (HR) = 1.423, CI = 1.084-1.869, P = 0.011). Our meta-analysis suggested that the GSTP1 IIe105Val, GSTM1 and GSTT1 null variants might be predictive factors for the efficacy of platinum-based chemotherapy to NSCLC patients. The use of GSTP1 IIe105Val, GSTM1 and GSTT1 null polymorphisms as predictive factors of efficacy of personalized platinum-based chemotherapy to NSCLC patients requires further verification with multi-center, multi-ethnic and large-sample-size pharmacogenetic studies.

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.

Pharmacogenomics of platinum-based chemotherapy sensitivity in NSCLC: toward precision medicine

Lung cancer is one of the leading causes of cancer-related death in the world. Platinum-based chemotherapy is the first-line treatment for non-small-cell lung cancer (NSCLC), however, the therapeutic efficiency varies remarkably among individuals. A large number of pharmacogenomics studies aimed to identify genetic variations which can be used to predict platinum response. Those studies are leading NSCLC treatment to the new era of precision medicine. In the current review, we provided a comprehensive update on the main recent findings of genetic variations which can be used to predict platinum sensitivity in the NSCLC patients.

MRP1 and GSTp1 expression in non-small cell lung cancer does not correlate with clinicopathological parameters: A Slovakian population study

We detected MRP1 (multidrug resistance-associated protein 1) and GSTp1 (glutathione-S-transferase p1) protein expression in samples of non-small cell lung cancer (NSCLC) and our results were compared to basic clinicopathological parameters. The indirect immunohistochemical method was used for localization of monitored proteins. A total of 135 tissue samples of NSCLC were characterized according to histopathological type of tumor. Next, we compared our results with basic clinicopathological parameters (histopathological type of tumor, tumor grade and TNM stage of disease). In MRP1 and GSTp1 positive tumor cells, strong brown cytoplasmic immunostaining was visible. In our set of samples 71% showed MRP1 positivity, while according to histopathological type the squamous cell carcinoma reached the highest level of positivity (76%). Our GSTp1 results showed that similarly to MRP1, 70% of samples were GSTp1 positive. According to histopathological type the adenocarcinoma samples showed the highest GSTp1 expression (77%). For precise statistical evaluation the Kruskal-Wallis, Chi-square and Mann-Whitney tests were used. We did not find any statistically significant correlations between MRP1 and clinicopathological parameters. In the group of GSTp1, by Mann-Whitney test we found a statistically significant correlation between GSTp1 and histological grade (p=0.025) in adenocarcinoma samples. As this was only one group of statistically significant correlation we wanted to confirm this finding. For this we applied also Chi-square test which revealed no statistically significant dependence (p=0.077). No statistically significant relation was seen in the coexpression of both proteins (p=0.753). Despite this, the majority of samples simultaneously expressed MRP1 and GSTp1 proteins. In conclusion, our results show that MRP1 and GSTp1 proteins represent independent prognostic features in NSCLC. Nevertheless, the clinical outcome in individual patients is often difficult to predict. Identification of the factors that characterize the resistant cases would permit immediate treatment of the patients with alternative therapeutic approaches.

Association of CYP1B1 Leu432Val polymorphism and lung cancer risk: an updated meta-analysis

BACKGROUND

Cytochrome P4501B1 (CYP1B1) a phase I enzyme, is involved in the activation of a broad spectrum of procarcinogens. Impacts on the catalytic activity of the CYP1B1 enzyme, as well as an association of the Leu432Val polymorphism with the risk of lung cancer, have been described; however, the results remain controversial.

METHODS

We conducted a meta-analysis of all available studies to clarify the effects of the Leu432Val polymorphism on lung cancer risks basing on 2,543 lung cancer cases and 3,304 controls from ten separate comparisons. We also performed subgroup analyses by ethnicity (categorized as Caucasian, Asian and African-American), gender, smoking status ,and histological type. A pooled odds ratio (OR) with 95% confidence interval (CI) was calculated to estimate the strength of the association.

RESULTS

A significantly increased risk was found in our meta-analysis in the overall population (Val/Val vs. Leu/Leu: OR = 1.371, 95% CI 1.137-1.652, P = 0.001). In subgroup analysis, significant associations with lung cancer susceptibility were also found in Caucasians (Val/Val vs. Leu/Leu: OR = 1.312, 95% CI 1.075-1.602, P = 0.008), females (Val/Val vs. Leu/Leu: OR = 1.472, 95% CI 1.097-1.976, P = 0.010), and smokers (dominant model Leu/Val + Val/Val vs. Leu/Leu: OR = 1.257, 95% CI 1.016-1.554, P = 0.035). Null results were noted in the subgroup analysis by histological type under different genetic models.

CONCLUSIONS

Our results suggest that the CYP1B1 Leu432Val polymorphism acts as a risk factor for the carcinogenesis of lung cancer.

Prognostic significance of GSTP1, XRCC1 and XRCC3 polymorphisms in non-small cell lung cancer patients

AIM

Individual differences in chemosensitivity and clinical outcome in non-small cell lung cancer (NSCLC) patients treatment with platinum-based chemotherapy may be due to genetic factors. Our study aimed to investigate the prognostic role of GSTP1, XRCC1 and XRCC3 in NSCLC patients treated with chemotherapy.

METHODS

A total of 460 cases were consecutively selected from The Affiliated Hospital of Nantong University between Jan. 2003 to Nov. 2006, and all were followed-up until Nov. 2011. Genotyping of GSTP1 Ile105Val, XRCC1 Arg194Trp, XRCC1 Arg399Gln and XRCC3 Thr241Met was conducted by duplex polymerase-chain-reaction with confronting-two-pair primer methods.

RESULTS

Patients with GSTP Val/Val exhibited a shorter survival time, and had a 1.89 fold greater risk of death than did those with the IIe/IIe genotype. For XRCC1 Arg194Trp, the variant genotype Trp/Trp was significantly associated with a decreased risk of death from NSCLC when compared with the Arg/Arg. Individuals carrying XRCC1 399Gln/Gln genotype had a longer survival time, with a lowered risk of death from NSCLC.

CONCLUSION

This study indicated that GSTP1 Ile105Val, XRCC1 Arg194Trp and XRCC1Arg399Gln genes have a role in modifying the effect of platinum-based chemotherapy for NSCLC patients in a Chinese population. Our findings provide information for therapeutic decisions for individualized therapy in NSCLC cases.

The effect of CYP1A1, GSTT1 and GSTM1 polymorphisms on the risk of lung cancer: a case-control study

Lung cancer, which is mainly affected by environmental factors, is a lethal malignancy. It is also important to investigate the effect of genetic factors on lung cancer aetiology. In this study, we aimed to investigate the distribution of CYP1A1*2C, GSTT1 and GSTM1 polymorphisms in Turkish lung cancer patients to determine whether any promoting effect of polymorphisms could cause development of lung cancer. For this purpose, genomic DNA samples obtained from peripheral blood of 128 patients with lung cancer and 122 healthy subjects were analyzed. Genotyping of polymorphic enzymes were carried out by polymerase chain reaction-restriction fragment length polymorphism methods. Although there were no significant differences between groups in terms of CYP1A1 polymorphism, the carriers of CYP1A1 Ile/Val genotype (odds ratio [OR] = 1.224, 95% confidence interval [CI]: 0.585-2.564) or CYP1A1 Val/Val genotype (OR = 3.058, 95% CI: 0.312-30.303) had an increased risk of lung cancer development. There was no statistical difference between groups in terms of both GSTT1 null genotype (OR = 1.114, 95% CI: 0.590-2.105) and GSTM1 null genotype (OR = 0.776, 95% CI: 0.466-1.290). This is the first case-control study investigating CYP1A1 Ile/Val, GSTT1 and GSTM1 polymorphisms in Turkish lung cancer patients. Although we suggest that other genes in addition to the proposed genes could play a role in lung cancer development, the results of our study will contribute to the possible associations between CYP1A1 Ile/Val, GSTT1 and GSTM1 gene polymorphism on the risk of lung cancer.

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.

Evaluation of glutathione S-transferase P1 polymorphisms (Ile105Val and Ala114Val) in patients with small cell lung cancer

AIMS

Glutathione S-transferase P1 (GSTP1) plays an important role in cellular protection against oxidative stress and toxic chemicals. Polymorphisms within GSTP1 are associated with alterations in enzyme activity, which may lead to development of lung disease and cancer. In this study, we aimed to investigate the GSTP1 Ile105Val and Ala114Val polymorphisms in patients with small cell lung cancer (SCLC).

PATIENTS/METHODS

GSTP1 Ile105Val polymorphism in exon 5 and GSTP1 Ala114Val polymorphism in exon 6 were determined by using polymerase chain reaction-restriction fragment length polymorphism techniques in 89 patients with SCLC and 108 control patients with chronic obstructive pulmonary disease (COPD). Genotype frequencies and cigarette smoking intensities were compared among SCLC and COPD patients.

RESULTS

There were significantly less SCLC patients with variant exon 6 genotypes than COPD patients (7.9% vs. 20.4%, p=0.007), while the number of patients with variant exon 5 genotypes were comparable among groups. SCLC and COPD patients with variant exon 6 genotype showed trends toward exhibiting reduced cigarette consumption.

CONCLUSIONS

The variant GSTP1 exon 6 genotype might be conferring protection against SCLC development. Whether this effect is associated with exposure to cigarette smoking needs to be clarified.

Association between GSTM1, GSTT1, and GSTP1 polymorphisms and lung cancer risk in a Turkish population

Several studies focused on investigating genetic polymorphisms in order to estimate genetic contribution to lung cancer often showed conflicting results. In this study, we investigated the role of GSTM1, GSTT1, GSTP1 exon 5 and exon 6 polymorphisms on developing lung cancer and histological subtypes in 213 lung cancer patients and 231 controls. GSTM1 null, GSTT1 null, and GSTP1 exon 5 variant genotypes did not show a significant risk for developing lung cancer overall. Significant association was noted between GSTP1 exon 6 variant genotypes and overall lung cancer risk (OR 2.17, 95% CI 1.25-3.78; P = 0.006). These results show that GSTP1 exon 6 polymorphism might be an important factor in determining lung cancer susceptibility in a Turkish population.

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.

The role of glutathione S-transferase P in signaling pathways and S-glutathionylation in cancer

Glutathione S-transferase P is abundantly expressed in some mammalian tissues, particularly those associated with malignancies. While the enzyme can catalyze thioether bond formation between some electrophilic chemicals and GSH, novel nondetoxification functions are now ascribed to it. This review summarizes recent material that implicates GSTP in mediating S-glutathionylation of specific clusters of target proteins and in reactions that define a negative regulatory role in some kinase pathways through ligand or protein:protein interactions. It is becoming apparent that GSTP participates in the maintenance of cellular redox homeostasis through a number of convergent and divergent mechanisms. Moreover, drug platforms that have GSTP as a target have produced some interesting preclinical and clinical candidates.