Gene silencing of SLC5A8 identified by genome-wide methylation profiling in lung cancer.

BACKGROUND: Aberrant DNA hypermethylation has been implicated as a component of an epigenetic mechanism that silences genes in cancers. METHODS: We performed a genome-wide search to identify differentially methylated loci between 26 tumor and adjacent non-tumor paired tissues from same lung cancer patients using restriction landmark genomic scanning (RLGS) analysis. Among 229 loci which were hypermethylated in lung tumors as compared to adjacent non-tumor tissues, solute carrier family 5, member 8 (SLC5A8) was one of the hypermethylated genes, and known as a tumor suppressor gene which is silenced by epigenetic changes in various tumors. We investigated the significance of DNA methylation in SLC5A8 expression in lung cancer cell lines, and 23 paired tumor and adjacent non-tumor lung tissues by reverse transcription-PCR (RT-PCR), quantitative methylation specific PCR (QMSP) and bisulfite modified DNA sequencing analyses. RESULTS: Reduced or lost expression of SLC5A8 was observed in 39.1% (9/23) of the tumor tissues as compared with paired adjacent non-tumor tissues. Bisulfite sequencing results of lung cancer cell lines and tissues which did not express SLC5A8 showed a densely methylated promoter region of SLC5A8. SLC5A8 was reactivated by treatment with DNA methyltransferase inhibitor, 5-Aza and/or HDAC inhibitor, trichostatin A (TSA) in lung cancer cell lines, which did not express SLC5A8. Hypermethylation was detected at the promoter region of SLC5A8 in primary lung tumor tissues as compared with adjacent non-tumor tissues (14/23, 60.9%). CONCLUSION: These results suggest that DNA methylation in the SLC5A8 promoter region may suppress the expression of SLC5A8 in lung tumor.

Randomized phase II trial of sulindac for lung cancer chemoprevention.

INTRODUCTION: Sulindac represents a promising candidate agent for lung cancer chemoprevention, but clinical trial data have not been previously reported. We conducted a randomized, phase II chemoprevention trial involving current or former cigarette smokers (≥30 pack-years) utilizing the multi-center, inter-disciplinary infrastructure of the Cancer Prevention Network (CPN). METHODS: At least 1 bronchial dysplastic lesion identified by fluorescence bronchoscopy was required for randomization. Intervention assignments were sulindac 150mg bid or an identical placebo bid for 6 months. Trial endpoints included changes in histologic grade of dysplasia (per-participant as primary endpoint and per lesion as secondary endpoint), number of dysplastic lesions (per-participant), and Ki67 labeling index. RESULTS: Slower than anticipated recruitment led to trial closure after randomizing participants (n=31 and n=30 in the sulindac and placebo arms, respectively). Pre- and post-intervention fluorescence bronchoscopy data were available for 53/61 (87%) randomized, eligible participants. The median (range) of dysplastic lesions at baseline was 2 (1-12) in the sulindac arm and 2 (1-7) in the placebo arm. Change in dysplasia was categorized as regression:stable:progression for 15:3:8 (58%:12%:31%) subjects in the sulindac arm and 15:2:10 (56%:7%:37%) subjects in the placebo arm; these distributions were not statistically different (p=0.85). Median Ki67 expression (% cells stained positive) was significantly reduced in both the placebo (30 versus 5; p=0.0005) and sulindac (30 versus 10; p=0.0003) arms, but the difference between arms was not statistically significant (p=0.92). CONCLUSIONS: Data from this multi-center, phase II squamous cell lung cancer chemoprevention trial do not demonstrate sufficient benefits from sulindac 150mg bid for 6 months to warrant additional phase III testing. Investigation of pathway-focused agents is necessary for lung cancer chemoprevention.

Generation of lung adenocarcinoma DNA aptamers for cancer studies.

Lung cancer is the most lethal malignancy in the world, and each year thousands of people die from this disease. Early detection has proven to increase the 5-year survival for this cancer in general, independent of the origination site in the lung. To address this challenge, we have used cell-based SELEX (Systematic Evolution of Ligands by Exponential Enrichment) to select a panel of aptamers capable of distinguishing lung adenocarcinoma cells from normal lung epithelial cells. These aptamers bind at physiological and formalin-fixed conditions and display affinity for their targets with apparent K(d')s in the nanomolar range. Our findings suggest that the selected aptamers have the potential to be used in clinical settings, as well as to improve classification of nonsurgical specimens, another current challenge in lung cancer.

A new method for lung cancer prognosis via centrosome image feature analysis.

OBJECTIVE: To predict survival of resected stage I non-small cell lung cancer (NSCLC) patients through quantitative analysis and classification of centrosome features. STUDY DESIGN: Disordered centrosome amplification leads to the loss of regulated chromosome segregation, aneuploidy and chromosome instability and may be a biomarker of cancer prognosis. Resected, stage I NSCLC tissues from survivor and fatal cases were immunostained with gamma-tubulin and scanned by confocal microscopy. Regions of interest were selected to include 1 cell and at least 1 centrosome. Four hundred forty-six regions were imaged, including 903 centrosomes whose features were extracted and measured. After segmentation, 12 centrosome features were measured. After optimization, 6 non-redundant features were selected for statistical analysis and classification. RESULTS: Two statistical methods showed that for each feature, centrosomes from survivors differed significantly from centrosomes of fatalities. Centrosomes were classified into survival or fatal outcomes by centrosome features using linear discriminant analysis, support vector machines (SVMs) and further optimized using SVMs with bagging. Ten-fold cross-validation was applied. Classification accuracies were 74%, 79% and 85%, respectively. CONCLUSION: Centrosome features can be a prognostic biomarker for resected stage I NSCLC and may indicate patients who would benefit from additional adjuvant therapy.

Longitudinal multistage model for lung cancer incidence, mortality, and CT detected indolent and aggressive cancers.

It is currently not known whether most lung cancers detected by computerized tomography (CT) screening are aggressive and likely to be fatal if left untreated, or if a sizable fraction are indolent and unlikely to cause death during the natural lifetime of the individual. We developed a longitudinal biologically-based model of the relationship between individual smoking histories and the probability for lung cancer incidence, CT screen detection, lung cancer mortality, and other-cause mortality. The longitudinal model relates these different outcomes to an underlying lung cancer disease pathway and an effective other-cause mortality pathway, which are both influenced by the individual smoking history. The longitudinal analysis provides additional information over that available if these outcomes were analyzed separately, including testing if the number of CT detected and histologically-confirmed lung cancers is consistent with the expected number of lung cancers "in the pipeline". We assume indolent nodules undergo Gompertz growth and are detectable by CT, but do not grow large enough to contribute significantly to symptom-based lung cancer incidence or mortality. Likelihood-based model calibration was done jointly to data from 6878 heavy smokers without asbestos exposure in the control (placebo) arm of the Carotene and Retinol Efficacy Trial (CARET); and to 3,642 heavy smokers with comparable smoking histories in the Pittsburgh Lung Screening Study (PLuSS), a single-arm prospective trial of low-dose spiral CT screening for diagnosis of lung cancer. Model calibration was checked using data from two other single-arm prospective CT screening trials, the New York University Lung Cancer Biomarker Center (NYU) (n=1,021), and Moffitt Cancer Center (Moffitt) cohorts (n=677). In the PLuSS cohort, we estimate that at the end of year 2, after the baseline and first annual CT exam, that 33.0 (26.9, 36.9)% of diagnosed lung cancers among females and 7.0 (4.9,11.7)% among males were overdiagnosed due to being indolent cancers. At the end of the PLuSS study, with maximum follow-up of 5.8 years, we estimate that due to early detection by CT and limited follow-up, an additional 2.2 (2.0,2.4)% of all diagnosed cancers among females and 7.1 (6.7,8.0)% among males would not have been diagnosed in the absence of CT screening. We also find a higher apparent cure rate for lung cancer among CARET females than males, consistent with the larger indolent fraction of CT detected and histologically confirmed lung cancers among PLuSS females. This suggests that there are significant gender differences in the aggressiveness of lung cancer. Females may have an inherently higher proportion of indolent lung cancers than males, or aggressive lung cancers may be brought into check by the immune system more frequently among females than males.

Does the source of death information affect cancer screening efficacy results? A study of the use of mortality review versus death certificates in four randomized trials.

BACKGROUND: Often in randomized controlled trials of cancer screening, cause of death is determined by a mortality review committee. However, little is known regarding how findings from mortality review compare to those from death certificates alone. PURPOSE: To examine the results of four different U. S. trials of cancer screening when death certificate data only were used, as compared to results using all available mortality review information. METHODS: Trials included were the Health Insurance Plan of New York breast screening trial (HIP), the Minnesota trial of fecal occult blood testing, and the Johns Hopkins and Mayo Lung Projects, which each examined chest x-ray and sputum cytology. The sensitivity, specificity, positive and negative predictive values, and Cohen's kappa for death certificates were calculated for all arms of all trials. Separate intention-to-screen analyses were conducted for each trial using cause of death information from either death certificates alone or full mortality review data. RESULTS: Generally there was excellent agreement between the death certificates and the mortality review committee as to the underlying cause of death (kappa >0.85 in all cases); death certificate agreement was similar between arms in all trials. Modest changes in the screening effectiveness estimates were observed when mortality review information was utilized, ranging from a 9% decrease to a 2% increase in the calculated mortality rate ratios. However, in one instance (HIP) a statistically significant benefit of screening was observed when mortality review committee data were used (rate ratio (RR) 0.77, 95% confidence interval (CI) 0.62- 0.95) but not when death certificate data were used (RR 0.82, 95% CI 0.65-1.03). LIMITATIONS: Although considered to be the gold standard, even carefully conducted mortality review may result in errors in cause of death assignment. CONCLUSIONS: For each trial, results were similar regardless of the source of cause of death information.

Quantificational and statistical analysis of the differences in centrosomal features of untreated lung cancer cells and normal cells.

OBJECTIVE: To distinguish untreated lung cancer cells from normal cells through quantitative analysis and statistical inference of centrosomal features extracted from cell images. STUDY DESIGN: Recent research indicates that human cancer cell development is accompanied by centrosomal abnormalities. For quantitative analysis of centrosome abnormalities, high-resolution images of normal and untreated cancer lung cells were acquired. After the images were preprocessed and segmented, 11 features were extracted. Correlations among the features were calculated to remove redundant features. Ten nonredundant features were selected for further analysis. The mean values of 10 centrosome features were compared between cancer and normal cells by the two-sample t-test; distributions of the 10 features of cancer and normal centrosomes were compared by the two-sample Kolmogorov-Smirnov test. RESULTS: Both tests reject the null hypothesis; the means and distributions of features coincide for normal and cancer cells. The 10 centrosome features separate normal from cancer cells at the 5% significance level and show strong evidence that all 10 features exhibit major differences between normal and cancer cells. CONCLUSION: Centrosomes from untreated cancer and normal bronchial epithelial cells can be distinguished through objective measurement and quantitative analysis, suggesting a new approach for lung cancer detection, early diagnosis and prognosis.

Randomized controlled trials of the efficacy of lung cancer screening by sputum cytology revisited: a combined mortality analysis from the Johns Hopkins Lung Project and the Memorial Sloan-Kettering Lung Study.

BACKGROUND: : Two randomized controlled trials of lung cancer screening initiated in the 1970s, the Johns Hopkins Lung Project and the Memorial Sloan-Kettering Lung Study, compared 1 arm that received annual chest X-ray and 4-monthly sputum cytology (dual-screen) to a second arm that received annual chest X-ray only. Previous publications from these trials reported similar lung cancer mortality between the 2 groups. However, these findings were based on incomplete follow-up, and each trial on its own was underpowered to detect a modest mortality benefit. METHODS: : The authors estimated the efficacy of lung cancer screening with sputum cytology in an intention-to-screen analysis of lung cancer mortality, using combined data from these trials (n = 20,426). RESULTS: : Over (1/2) of squamous cell lung cancers diagnosed in the dual-screen group were identified by cytology; these cancers tended to be more localized than squamous cancers diagnosed in the X-ray only arm. After 9 years of follow-up, lung cancer mortality was slightly lower in the dual-screen than in the X-ray only arm (rate ratio [RR], 0.88; 95% confidence interval [CI], 0.74-1.05). Reductions were seen for squamous cell cancer deaths (RR, 0.79; 95% CI, 0.54-1.14) and in the heaviest smokers (RR, 0.81; 95% CI, 0.67-1.00). There were also fewer deaths from large cell carcinoma in the dual-screen group, although the reason for this is unclear. CONCLUSIONS: : These data are suggestive of a modest benefit of sputum cytology screening, although we cannot rule out chance as an explanation for these findings. Cancer 2009. (c) 2009 American Cancer Society.

Dietary n-3 polyunsaturated acids and smoking-related chronic obstructive pulmonary disease.

BACKGROUND: Fish contain n-3 polyunsaturated fatty acids, principally eicosapentaenoic acid and docosahexaenoic acid, which are known to interfere with the body's inflammatory response and may be of benefit in chronic inflammatory conditions. METHODS: We studied the relation between the dietary intake of n-3 fatty acids and chronic obstructive pulmonary disease (COPD) in 8960 current or former smokers participating in a population-based study of artheroscierosis. Intake of fatty acids was estimated with a dietary questionnaire. The presence of COPD was assessed by a questionnaire on respiratory symptoms and by spirometry. Three case definitions of COPD were used: symptoms of chronic bronchitis (667 subjects), physician-diagnosed emphysema reported by the subject (185 subjects), and spirometrically detected COPD (197 subjects). RESULTS: After control for pack-years of smoking, age, sex, race, height, weight, energy intake, and educational level docosahexaenoic acid was inversely related to the ris of COPD in a quantity-dependent fashion. The adjusted odds ratio for the highest quartile was 0.66 for chronic bronchitis (95 percent confidence interval, 0.52 to 0.85; P<0.001 for linear trend across the range of intake value), 0.31 for physician-diagnosed emphysema (95 percent confidence interval, 0.18 to 0.52; P for liner trend, 0.003), and 0.50 for spirometrically detected COPD (95 percent confidence interval, 0.32 to 0.79; P for linear trend, 0.007). CONCLUSION: A high dietary intake of n-3 fatty acids may protect cigarette smokers against COPD.

Respiratory effects of household exposures to tobacco smoke and gas cooking.

The records of 1,724 residents of Washington County, Maryland, who had participated in 2 studies of respiratory symptoms and ventilatory function were analyzed to evaluate the effects of exposures at home to tobacco smoke generated by other members of their households and to fumes from the use of gas as a cooking fuel. Currently smoking subjects showed the highest frequency of respiratory symptoms and impaired ventilatory function; former smokers showed a lower frequency of these findings; and persons who had never smoked had the lowest prevalence of abnormal respiratory findings. The presence of a smoker in the household other than the subject was not associated with the frequency of respiratory symptoms, and only suggestively associated with evidence of impaired ventilatory function. The use of gas for cooking was related to an increased frequency of respiratory symptoms and impaired ventilatory function among men, being most marked among men who had never smoked. There was no evidence that cooking with gas was harmful to women.

Computerized analysis of cellular features and biomarkers for cytologic diagnosis of early lung cancer.

OBJECTIVE: To present a set of novel computerized analysis algorithms to construct a computer-aided cytologic diagnosis (CACD) system to differentiate lung cancer biomarkers and identify cancer cells in the tissue-based specimen images. STUDY DESIGN: Molecular methods, including application of cancer-specific markers, may prove to be complementary to cytology diagnosis, especially when they are combined with CACD system for biomarker assessment. We trained a novel CACD system to recognize expression of the cancer biomarkers histone H2AX in lung cancer cells and then tested the accuracy of this system to distinguish resected lung cancer from preneoplastic and normal tissues. The major characteristics of CACD algorithms is to adapt detection parameters according to cellular image contents. Our newly developed wavelet transform is able to adaptively select different resolution and orientation features based on image content requirements. RESULTS: Visual, statistical and quantitative results as CACD performance evaluation are presented in this paper. CONCLUSION: The presented algorithms and CACD system for cellular feature enhancement, segmentation and classification are very important in distinguishing benign and malignant lesions.

Computed tomography screening and lung cancer outcomes.

CONTEXT: Current and former smokers are currently being screened for lung cancer with computed tomography (CT), although there are limited data on the effect screening has on lung cancer outcomes. Randomized controlled trials assessing CT screening are currently under way. OBJECTIVE: To assess whether screening may increase the frequency of lung cancer diagnosis and lung cancer resection or may reduce the risk of a diagnosis of advanced lung cancer or death from lung cancer. DESIGN, SETTING, AND PARTICIPANTS: Longitudinal analysis of 3246 asymptomatic current or former smokers screened for lung cancer beginning in 1998 either at 1 of 2 academic medical centers in the United States or an academic medical center in Italy with follow-up for a median of 3.9 years. INTERVENTION: Annual CT scans with comprehensive evaluation and treatment of detected nodules. MAIN OUTCOME MEASURES: Comparison of predicted with observed number of new lung cancer cases, lung cancer resections, advanced lung cancer cases, and deaths from lung cancer. RESULTS: There were 144 individuals diagnosed with lung cancer compared with 44.5 expected cases (relative risk [RR], 3.2; 95% confidence interval [CI], 2.7-3.8; P<.001). There were 109 individuals who had a lung resection compared with 10.9 expected cases (RR, 10.0; 95% CI, 8.2-11.9; P<.001). There was no evidence of a decline in the number of diagnoses of advanced lung cancers (42 individuals compared with 33.4 expected cases) or deaths from lung cancer (38 deaths due to lung cancer observed and 38.8 expected; RR, 1.0; 95% CI, 0.7-1.3; P = .90). CONCLUSIONS: Screening for lung cancer with low-dose CT may increase the rate of lung cancer diagnosis and treatment, but may not meaningfully reduce the risk of advanced lung cancer or death from lung cancer. Until more conclusive data are available, asymptomatic individuals should not be screened outside of clinical research studies that have a reasonable likelihood of further clarifying the potential benefits and risks.

Polymorphisms in the promoter region of neutrophil elastase gene and lung cancer risk.

The neutrophil elastase (NE) gene encodes a powerful serine protease that is involved in the process of normal tissue turnover, natural host defense or tissue damage in acute and chronic inflammatory disorders. Furthermore, NE was suggested as one of the determinant factors of individual susceptibility to lung cancer resulting from imbalance between alpha1-antitrypsin (AT) and NE. To determine whether NE plays a role in risk for lung cancer, we screened polymorphisms in the promoter region of the NE gene and assessed the role of the NE polymorphisms in the risk for lung cancer. We confirmed three previously identified polymorphisms which are located at -903, -741, and extra 52 bp STS relative to the transcription initiation site. In addition, two new polymorphisms at -832 (G/T) and -789 (C/T) were identified. Their rare allelic frequencies of new polymorphism are 0.02 and 0.01, respectively, among Caucasians. The prevalence of the NE -903 (T/T) and (T/G) genotypes were 0.88 and 0.12 in controls as compared to 0.96 and 0.04 in lung cancer patients using genomic DNA isolated from 113 Caucasian lung cancer cases and 131 controls. A significant increase in lung cancer risk was observed for expected high NE activity genotypes (OR=3.2, 95% CI=1.02-10.3) as compared to low NE activity genotypes. These results were consistent with previous in vitro functional analysis, which reported an approximately two-fold increase enzyme expression with the -903T/-741G allele as compared to the -903G/-741A variant. These results confirm that the NE promoter region polymorphisms may influence in risk for lung cancer.

Polymorphisms for microsomal epoxide hydrolase and genetic susceptibility to COPD.

Although smoking is the major causal factor in the development of chronic obstructive pulmonary disease (COPD), only 10-20% of chronic heavy cigarette smokers develop symptomatic COPD, which suggests the presence of genetic susceptibility. The human microsomal epoxide hydrolase (EH) is a metabolizing enzyme which involves the process of numerous reactive epoxide intermediates and contains polymorphic alleles which are associated with altered EH activity and may be linked to increased risk for COPD. To determine whether the EH polymorphisms contributed to increased risk for COPD, prevalence of the EH codons 113 and 139 polymorphisms were compared between COPD patients and controls by a PCR-RFLP analysis using genomic DNA isolated from 131 COPD patients and 262 individually matched controls by age (+/-5 years) among Caucasians with 2:1 ratio. Significantly increased risk for COPD was observed for subjects with the EH(113His/His) genotypes (OR=2.4, 95% CI=1.1-5.1). These results were consistent with the fact that a significant trend towards increased risk was observed with predicted less protective EH codon 113 genotypes (p=0.03, trend test). A similar association was not observed for EH codon 139 polymorphism. As expected, a significant correlation between smoking dose and severity of COPD was observed (p<0.001). These results suggest that EH codon 113 polymorphism may modify risk for COPD.

CpG island hypermethylation profiling of lung cancer using restriction landmark genomic scanning (RLGS) analysis.

Lung cancer remains the leading cause of cancer related mortality, accounting for almost one-third of cancer deaths in men and one-fourth of cancer deaths in women; 160,440 lung cancer deaths are expected in 2004. Survival from lung cancer depends mainly upon the stage at presentation. As localized tumors generally do not cause symptoms, the disease is usually diagnosed in symptomatic patients at advanced stages when the prognosis is poor. As a result, the overall 5-year lung cancer survival rate is only 15%. It is well known that epigenetic alterations such as DNA methylation of CpG dinucleotides located in CpG islands within the regulatory (promoter) regions of genes are associated with transcriptional silencing in cancer. Promoter hypermethylation of critical pathway genes could identify potential biomarkers for lung cancer risk. Our goal for this study is to identify novel hypermethylated genes in lung cancer. We have investigated the methylation profiles of DNA samples from 14 paired lung tumor and adjacent normal tissues resected from the same individuals using restriction landmark genomic scanning (RLGS). We could assess the DNA methylation status of an average of 2,012 CpG islands for each tumor. We identified 162 differentially methylated loci where CpG islands were hypermethylated in lung tumors but not in adjacent non-cancer tissues. Among 162 sites of differential DNA methylation, detected from at least one tumor/normal pair, 21 hypermethylated genes were identified that were not reported previously as hypermethylated in lung tumor tissue.

Data mining techniques for cancer detection using serum proteomic profiling.

OBJECTIVE: Pathological changes in an organ or tissue may be reflected in proteomic patterns in serum. It is possible that unique serum proteomic patterns could be used to discriminate cancer samples from non-cancer ones. Due to the complexity of proteomic profiling, a higher order analysis such as data mining is needed to uncover the differences in complex proteomic patterns. The objectives of this paper are (1) to briefly review the application of data mining techniques in proteomics for cancer detection/diagnosis; (2) to explore a novel analytic method with different feature selection methods; (3) to compare the results obtained on different datasets and that reported by Petricoin et al. in terms of detection performance and selected proteomic patterns. METHODS AND MATERIAL: Three serum SELDI MS data sets were used in this research to identify serum proteomic patterns that distinguish the serum of ovarian cancer cases from non-cancer controls. A support vector machine-based method is applied in this study, in which statistical testing and genetic algorithm-based methods are used for feature selection respectively. Leave-one-out cross validation with receiver operating characteristic (ROC) curve is used for evaluation and comparison of cancer detection performance. RESULTS AND CONCLUSIONS: The results showed that (1) data mining techniques can be successfully applied to ovarian cancer detection with a reasonably high performance; (2) the classification using features selected by the genetic algorithm consistently outperformed those selected by statistical testing in terms of accuracy and robustness; (3) the discriminatory features (proteomic patterns) can be very different from one selection method to another. In other words, the pattern selection and its classification efficiency are highly classifier dependent. Therefore, when using data mining techniques, the discrimination of cancer from normal does not depend solely upon the identity and origination of cancer-related proteins.

The human 8-oxoguanine DNA N-glycosylase 1 (hOGG1) DNA repair enzyme and its association with lung cancer risk.

OBJECTIVE: The human 8-oxoguanine DNA N-glycosylase 1 gene encodes a DNA glycosylase that is involved in the base excision repair of 8-hydroxy-2-deoxyguanine from oxidatively-damaged DNA and expressed in lung tissue. The codon 326 polymorphism in the hOGG1 gene has been suggested to reduce DNA repair enzyme activity based on in vitro functional analysis. The goal of the present study is to determine whether the codon 326 polymorphism was significantly associated with alterations in individual risk for lung cancer. METHODS: To determine whether hOGG1 plays a role in risk for lung cancer, we measured the prevalence of the Ser326Cys polymorphism in incident lung cancer patients and matched non-cancer controls. hOGG1 genotyping was performed by PCR-restriction fragment length polymorphism analysis of genomic DNA isolated from 179 Caucasian lung cancer cases and 358 controls individually matched in a 1:2 ratio by race-, sex- and age (+/- 5 years). RESULTS: Significantly increased risk for lung cancer was observed for both the hOGG1 326 (odds ratio [OR] = 1.9, 95% confidence interval [CI] = 1.2-2.9) and hOGG1 326 genotypes (OR = 3.8, 95% CI = 1.4-10.6). The increased risk for lung cancer was observed for subjects with both the hOGG1 326 (OR = 1.7, 95% CI = 1.1-2.8) and hOGG1 326 genotypes (OR = 4.9, 95% CI = 1.5-16.1) in ever-smokers. A significant association was found between hOGG1 genotypes and lung cancer risk with a dose-dependent effect with smoking. Significantly increased risk for variant hOGG1 genotypes was observed for all non-small cell lung cancer patients. CONCLUSION: These results suggest that the hOGG1 Ser326Cys polymorphism plays an important role in the risk for lung cancer and is linked to exposure to tobacco smoke.

Epigenetic down-regulation of death-associated protein kinase in lung cancers.

PURPOSE: Death-associated protein kinase (DAPK) is a pro-apoptotic serine/threonine kinase involved in apoptosis. Aberrant methylation of DAPK was reported in lung cancers by methylation-specific PCR. However, we were unable to relate methylation with gene silencing with the same methodology. Our goals were to develop a methodology that related methylation with gene silencing and use it to study the state of the gene in lung cancers. EXPERIMENTAL DESIGN AND RESULTS: Using a semiquantitative real-time reverse transcription-PCR, DAPK expression was lower in lung cancers than in corresponding nonmalignant bronchial epithelial cells in five of six primary short-term cultures. In continuous cell lines, mRNA expression was down-regulated, as well as compared with nonmalignant bronchial epithelial cells, and its protein was not detected by Western blotting in 17 of 23 (74%) cell lines. We investigated methylation status of 5' flanking region of DAPK by combined bisulfite restriction analysis and bisulfited DNA sequencing. Aberrant methylation was detected in 21 of 48 (44%) cell lines, 2 of 6 primary cultured tumors, and 14 of 38 (37%) primary lung cancers, although varying degrees of methylation were noticed. Furthermore, bisufite sequence data suggested that aberrant methylation might occur selectively at some CpG dinucleotides in cell lines which had absent expression. Treatment with 5-aza-2'-deoxycytidine restored DAPK expression in heavily methylated cell lines tested, and histone deacetylase inhibitor trichostatin A alone restored DAPK expression in some methylated cell lines as well. CONCLUSIONS: Our major findings are: (a) DAPK expression is frequently down-regulated in lung cancers; (b) aberrant methylation of DAPK is frequent in lung cancers, although considerable heterogeneity of methylation is present, and some specific CpG dinucleotides are often methylated in expression negative lung cancers; and (c) besides methylation and histone deacetylation, there may be other mechanisms for down-regulation of DAPK expression.

A systematic review and lessons learned from early lung cancer detection trials using low-dose computed tomography of the chest.

BACKGROUND: Computed tomography (CT) screening of the chest has shown promise for early detection of lung cancer, but evidence for a reduction in lung cancer mortality by CT screening is not available. METHODS: We reviewed 208 articles to synthesize available evidence for efficacy of CT screening in detecting potentially curative stages of lung cancer and for evidence in reducing lung cancer mortality. Other outcomes of interest included detection rate of cancer and of suspicious lesions, histology and stage of cancer at detection, screening-related morbidity, and the identification of populations uniquely suited for CT screening. We identified eight papers that reported the outcomes for CT of the chest in lung cancer screening. RESULTS: Since none of the studies utilized a control group, quantitative pooling was not done. In two studies, both CT and chest radiography (CXR) were used as screening tools in the same cohorts. A total of 19,107 subjects were screened using CT. The detected prevalence rate for lung cancer ranged from 0.40% to 13.6% and was a function of the subjects' age and smoking history. CT screening resulted in a 3-fold higher detection rate and a 5-fold increase in the rate of resectable cancers compared to CXR. Data on lung cancer and overall mortality and screening-related morbidity and mortality were incomplete. CT screening resulted in selective detection of adenocarcinomas with an approximately 2- to 3-fold oversampling of this histologic subtype. The positive predictive value of CT screening was highest for subjects in the 8th decade of life, and it was virtually nil for those in their 5th decade. CONCLUSIONS: Evidence regarding lung cancer screening by CT shows that this technology detects earlier-stage and smaller lung cancers with greater frequency than other screening methods. To date, no trials have demonstrated that CT screening leads to a reduction in lung cancer mortality. Until mortality trials are completed, low-dose CT screening should be considered an investigative tool rather than the standard of care.