Aberrant promoter methylation of multiple genes in non-small cell lung cancers

Aberrant methylation of CpG islands acquired in tumor cells in promoter regions is one method for loss of gene function. We determined the frequency of aberrant promoter methylation (referred to as methylation) of the genes retinoic acid receptor beta-2 (RARbeta), tissue inhibitor of metalloproteinase 3 (TIMP-3), p16INK4a, O6-methylguanine-DNA-methyltransferase (MGMT), death-associated protein kinase (DAPK), E-cadherin (ECAD), p14ARF, and glutathione S-transferase P1 (GSTP1) in 107 resected primary non-small cell lung cancers (NSCLCs) and in 104 corresponding nonmalignant lung tissues by methylation-specific PCR. Methylation in the tumor samples was detected in 40% for RARbeta, 26% for TIMP-3, 25% for p16INK4a, 21% for MGMT, 19% for DAPK, 18% for ECAD, 8% for p14ARF, and 7% for GSTP1, whereas it was not seen in the vast majority of the corresponding nonmalignant tissues. Moreover, p16INK4a methylation was correlated with loss of p16INK4a expression by immunohistochemistry. A total of 82% of the NSCLCs had methylation of at least one of these genes; 37% of the NSCLCs had one gene methylated, 22% of the NSCLCs had two genes methylated, 13% of the NSCLCs had three genes methylated, 8% of the NSCLCs had four genes methylated, and 2% of the NSCLCs had five genes methylated. Methylation of these genes was correlated with some clinicopathological characteristics of the patients. In comparing the methylation patterns of tumors and nonmalignant lung tissues from the same patients, there were many discordancies where the genes methylated in nonmalignant tissues were not methylated in the corresponding tumors. This suggests that the methylation was occurring as a preneoplastic change. We conclude that these findings confirm in a large sample that methylation is a frequent event in NSCLC, can also occur in smoking-damaged nonmalignant lung tissues, and may be the most common mechanism to inactivate cancer-related genes in NSCLC.     

Smoke exposure,histologic type and geography-related differences in the methylation profiles of non-small cell lung cancer

Aberrant methylation of several known or putative tumor suppressor genes occurs frequently during the pathogenesis of lung cancers. There are major smoke exposure, histology, geography and gender-related changes in non-small cell lung cancer (NSCLC). We investigated smoking-related, histologic, geographic and gender differences in the methylation profiles of resected NSCLCs. We examined 514 cases of NSCLC and 84 corresponding nonmalignant lung tissues from 4 countries (USA, Australia, Japan and Taiwan) for the methylation status of 7 genes known to be frequently methylated in lung cancers [p16, RASSF1A (RAS association domain family 1), APC, RARbeta, CDH13, MGMT and GSTP1]. Multivariate analyses were used for data analysis. Adenocarcinoma was the major histologic type in women and never smokers; analyses that involved smoke exposure and gender were limited to this histology. Our major findings are a) methylation status of any single gene was largely independent of methylation status of other genes; b) the rates of methylation of p16 and APC and the mean Methylation Index (MI), a reflection of the overall methylation status, were significantly higher in ever smokers than in never smokers; c) the mean MI of tumors arising in former smokers was significantly lower than the mean of current smokers; d) the methylation rates of APC, CDH13 and RARbeta were significantly higher in adenocarcinomas than in squamous cell carcinomas; e) methylation rates of MGMT and GSTP1 were significantly higher in the USA and Australian cases than in those from Japan and Taiwan; and (f) no significant gender-related differences in methylation patterns were noted. Our findings demonstrate important smoke exposure, histologic type and geography-related differences in the methylation profiles of NSCLC tumors.     

Hypermethylation of multiple genes in pancreatic adenocarcinoma

Hypermethylation of CpG islands is a common mechanism by which tumor suppressor genes are inactivated. We studied 45 pancreatic carcinomas and 14 normal pancreata for aberrant DNA methylation of CpG islands of multiple genes and clones using methylation-specific PCR (MSP) and bisulfite-modified sequencing. Using MSP, we detected aberrant methylation of at least one locus in 60% of carcinomas. The genes analyzed included RARbeta (methylated in 20%), p16 (18%), CACNA1G (16%), TIMP-3 (11%), E-cad (7%), THBS1 (7%), hMLH1 (4%), DAP kinase (2%), and MGMT (0%). In addition, aberrant methylation was found in three CpG islands (MINT31, -1, and -2) in 38, 38, and 14% of carcinomas, respectively. Hypermethylation was largely confined to the carcinomas with only three loci (E-cad, DAP kinase, and MINT2) harboring methylation in some normal pancreata (36, 21, and 14%, respectively). Simultaneous methylation of at least four loci was observed in 5 of 36 (14%) pancreatic adenocarcinomas. We defined this subgroup of pancreatic adenocarcinomas as "CpG island-methylator-phenotype positive (CIMP+)." Two of four carcinomas with microsatellite instability harbored promoter hypermethylation of hMLH1, and both cases were CIMP+. Thus, we conclude that many pancreatic carcinomas hypermethylate a small percentage of genes, whereas a subset displays a CIMP+ phenotype.     

CpG island methylation in carcinoid and pancreatic endocrine tumors

Carcinoid tumors and pancreatic endocrine tumors (PETs) are uncommon neuroendocrine neoplasms and their genetic alterations are not well characterized. CpG island methylation is a mechanism of gene silencing, and concordant methylation of multiple CpG islands as CpG island methylator phenotype (CIMP) has been described in tumors. The aim of this study was to evaluate CIMP in carcinoid tumors and PETs. We studied 16 carcinoid tumors, 11 PETs, and 22 associated normal mucosa or pancreas. Methylation status of the p14, p16, cyclo-oxygenase 2 (COX2), O(6)-methyl-guanine methyltransferase (MGMT), estrogen receptor (ER), thrombospondin 1 (THBS1), retinoic acid receptor beta 2 (RARbeta), T-type calcium channel (CACNA1G), and multiple endocrine neoplasia type-1 (MEN1) genes, and of MINT1, MINT2, MINT25, MINT27 and MINT31 loci was evaluated by methylation-specific-PCR (MSP) or combined bisulfite restriction analysis (COBRA). Carcinoid tumors were frequently methylated at RARbeta, MGMT, p16, COX2, p14, THBS1, and ER ranging from 25 to 63% of tumors. Other CpG islands were infrequently methylated or unmethylated. The adjoining normal mucosa was also methylated for ER, COX2, and RARbeta, but methylation at p14, p16, THBS1, and MGMT was tumor-specific. By contrast, PETs and normal pancreas were frequently methylated only at ER. Methylation was more frequent in carcinoid tumors than PETs at MGMT (25 versus 0%, p = 0.03), THBS1 (44 versus 9%, p = 0.04), p14 (44 versus 9%, p = 0.04) and RARbeta (25 versus 0%, p = 0.03). Loss of p16 protein expression correlated with methylation of p16 gene in carcinoid tumors (p = 0.006). Our study indicates that methylation profile of carcinoid tumors differs from PETs, reflecting different molecular pathogenesis.     

Differential impact of p16 inactivation by promoter methylation in non-small cell lung and colorectal cancer: clinical implications

Inactivation of p16 has been reported as one of the more frequent events in human carcinogenesis. In order to contribute to the knowledge of the impact of p16 silencing by promoter methylation, we have investigated p16 expression and inactivation of p16 by methylation in two of the major types of human cancer, non-small cell lung cancer (NSCLC) and colorectal cancer (CRC). p16 expression was evaluated by Western blot, and p16 promoter methylation by a methylation-specific PCR procedure (MSP). Clinical correlations were established using the chi-square test, and distributions of disease-free survival (DFS) were estimated with the Kaplan-Meier method. Analyses for p16 revealed that 61.22% (60 of 98) of NSCLCs, and 32.9% (26 of 79) of CRCs here considered, lacked p16 expression. Moreover, 36.7% (22/60) of the non-small cell lung tumours without p16 expression showed p16 promoter methylation, detecting a significant correlation between p16 methylation and the histological subtype of squamous cell carcinomas (SCC) (P=0.04). With respect to CRCs, p16 promoter methylation was observed in 26.9% of tumours that lacked p16 expression (7/26), all tumours studied showing partial methylation. Survival studies demonstrated a clear correlation between p16 negative expression and poor prognosis in NSCLC patients. Moreover, we found a trend toward poor clinical evolution in the group of patients with tumours showing total p16 methylation, in NSCLC, without statistically significant differences in CRC. In conclusion, our results indicate that p16 alterations constitute a major molecular abnormality in NSCLC with a considerable prognosis impact, promoter methylation being an important mechanism involved in p16 silencing. In CRC, however, p16 promoter methylation could be considered as a less definitive molecular factor without prognostic implication, since partial methylation constitutes a prevalent mechanism.     

Promoter hypermethylation of tumor suppressor and tumor-related genes in non-small cell lung cancers

Aberrant methylation of promoter CpG islands is known to be a major inactivation mechanism of tumor suppressor and tumor-related genes. To determine the clinicopathological significance of gene promoter methylation in non-small cell lung cancer (NSCLC), we examined the promoter methylation status of the APC, DAP-kinase, E-cadherin, GSTP1, hMLH1, p16, RASSF1A and RUNX3 genes in 75 NSCLCs and corresponding non-neoplastic lung tissues by methylation-specific PCR (MSP). The frequencies of methylation in NSCLCs and corresponding non-neoplastic lung tissues were: 37% (28 of 75) and 48% (36 of 75) for APC , 28% (21 of 75) and 13% (10 of 75) for DAP-kinase , 29% (22 of 75) and 15% (11 of 75) for E-cadherin , 1% (1 of 75) and 0% (0 of 75) for GSTP1 , 7% (5 of 75) and 0% (0 of 75) for hMLH1 , 31% (23 of 75) and 0% (0 of 75) for p16 , 43% (32 of 75) and 4% (3 of 75) for RASSF1A , and 20% (15 of 75) and 3% (2 of 75) for RUNX3 , respectively. Methylation of p16 was more frequent in squamous cell carcinomas than in adenocarcinomas ( P <0.05), and was associated with tobacco smoking ( P <0.05). On the contrary, methylation of APC and RUNX3 was more frequent in adenocarcinomas than in squamous cell carcinomas ( P <0.05). Thus, a different set of genes is thought to undergo promoter methylation, which leads to the development of different histologies. In addition, methylation of p16, RASSF1A and RUNX3 was mostly cancer-specific ( P <0.05), and may be utilized as a molecular diagnostic marker of NSCLCs.     

Aberrant promoter methylation in bronchial epithelium and sputum from current and former smokers

Recent studies from our laboratory suggest that gene-specific methylation changes in sputum could be good intermediate markers for the early detection of lung cancer and defining the efficacy of chemopreventive interventions. The purpose of our study was to determine the prevalence for aberrant promoter methylation of the p16, O(6)-methylguanine-DNA methyltransferase (MGMT), death-associated protein (DAP) kinase, and Ras effector homologue (RASSFIA) genes in nonmalignant bronchial epithelial cells from current and former smokers in a hospital-based, case control study of lung cancer. The relationship between loss of heterozygosity, at 9p and p16 methylation in bronchial epithelium and the prevalence for methylation of these four genes in sputum from cancer-free, current and former smokers were also determined. Aberrant promoter methylation of p16 was seen in at least one bronchial epithelial site from 44% of cases and controls. Methylation of the DAP kinase gene was seen in only 1 site from 5 cases and 4 controls, whereas methylation of the RASSFIA was not detected in the bronchial epithelium. Promoter methylation for p16 and DAP kinase was seen as frequently in bronchial epithelium from current smokers as from former smokers. No promoter methylation of these genes was detected in bronchial epithelium from never-smokers. Methylation of the p16 gene was detected in sputum from 23 of 66 controls. DAP kinase gene promoter methylation was also seen in sputum from 16 controls, and 8 of these subjects were positive for p16 methylation. Methylation of the MGMT gene was seen in sputum from 9 controls, whereas RASSFIA promoter methylation was only seen in 2 controls. The correlation between p16 status in the bronchial epithelium obtained from lung lobes that did not contain the primary tumor and the tumor itself was examined. Seventeen of 18 tumors (94%) showed an absolute concordance, being either methylated in the tumor and at least 1 bronchial epithelial site, or unmethylated in both tumor and bronchial epithelium. These results indicate that aberrant promoter hypermethylation of the p16 gene, and to a lesser extent, DAP kinase, occurs frequently in the bronchial epithelium of lung cancer cases and cancer-free controls and persists after smoking cessation. The strong association seen between p16 methylation in the bronchial epithelium and corresponding primary tumor substantiates that inactivation of this gene, although not transforming by itself, is likely permissive for the acquisition of additional genetic and epigenetic changes leading to lung cancer.     

Aberrant methylation in promoter-associated CpG islands of multiple genes in relapsed childhood acute lymphoblastic leukemia

Methylation profile was analyzed in nine cases of relapsed childhood acute lymphoblastic leukemia (ALL) for p14, p15, p16, Rb, MGMT, APC, hMLH1, RARbeta, RIZ, DAPK, and FHIT genes by using methylation specific polymerase chain reaction (MSP) analysis. Frequency of methylation in each gene was: MGMT, 56%; RARbeta, 44%; and p16, 22%, respectively. None of the p14, p15, Rb, APC, hMLH1, RIZ, DAPK, and FHIT genes were hypermethylated. Five (56%) of 9 cases showed methylation of at least one gene. All of the samples with hypermethylation in p16 and MGMT gene at relapse, had already acquired the change at the time of initial diagnosis. Interestingly, three of 4 cases with RARbeta gene methylation at relapse did not have methylation of this gene at the time of initial presentation. These results suggest that hypermethylation might be involved in the relapse of childhood ALL.     

DNA methylation changes in multiple myeloma.

Using a candidate gene approach, we analyzed the methylation status of the promoter-associated CpG islands of 11 well-characterized tumor suppressor genes by methylation-specific polymerase chain reaction in five multiple myeloma (MM) cell lines and 56 patients with malignant plasma cell disorders. The frequency of aberrant methylation among the patient samples was 46.4% for SOCS-1, 35.7% for p16, 21.4% for E-cadherin, 12.5% for DAP kinase and p73, 1.8% for p15, MGMT as well as RARbeta, and 0% for TIMP-3, RASSF1A and hMLH1. We found at least one hypermethylated gene in 80.4% of the primary patient samples, while 33.9% harbored two or more hypermethylated genes. For the first time, we show that p73 may be hypermethylated in MM and thus be involved in the pathogenesis of plasma cell disorders. Hypermethylation of p16 at diagnosis was associated with a poorer prognosis. In patients with plasma cell leukemia, we found frequent simultaneous hypermethylation of p16, E-cadherin and DAP kinase. We conclude that aberrant methylation of tumor suppressor genes is a common event in malignant plasma cell disorders and that there is a correlation between methylation patterns and clinical characteristics in MM patients.     

Aberrant methylation of CXCL12 in non-small cell lung cancer is associated with an unfavorable prognosis

Chemokines play an important role in the pathogenesis of non-small cell lung cancer (NSCLC). However, aberrant methylation of CXCL12 has not been examined in NSCLC. CXCL12 mRNA expression and methylation were examined in 17 NSCLC cell lines by RT-PCR and methylation-specific PCR (MSP). MSP was performed on 236 tumor specimens from NSCLC patients who received curative intent surgery. CXCL12 and CXCR4 protein expression was examined in 90 of the 236 NSCLC specimens by immunohistochemistry. Down-regulation of CXCL12 expression was found in 10 of 17 (59%) NSCLC cell lines compared with normal bronchial cells. Treatment of 8 expression-negative cell lines with a demethylating agent restored expression in all cases. Twelve cell lines (71%) showed aberrant methylation, and good concordance between methylation and expression was present. Aberrant methylation occurred in 85 out of 236 (36%) primary NSCLCs in a tumor-specific manner. In multivariate analysis, CXCL12 methylation correlated strongly and independently with prognosis both in all patients with NSCLCs and in those with stage I NSCLCs (hazard ratio=1.68, P=0.015 and hazard ratio=3.58, P=0.017). Secreted protein CXCL12 and its receptor CXCR4 were abundant in NSCLC cells (72 out of 90, 80%; 57 out of 90, 63%) and correlated with the progression of NSCLCs. In conclusion, epigenetic silencing of CXCL12 is a frequent event in NSCLCs, and could be an independent and powerful prognostic marker in patients with NSCLCs and those with stage I disease. Analysis for CXCL12 may provide novel opportunities for prognosis and therapy of resected NSCLCs.     

Tumor-specific methylation in bronchial lavage for the early detection of non-small-cell lung cancer.

PURPOSE: The aim of this study was to identify tumor-specific methylation in bronchial lavage for the early detection of non-small-cell lung cancer (NSCLC) by differentiating the age-related methylation from the tumor-specific methylation in NSCLC. PATIENTS AND METHODS: Eighty-five NSCLC patients and 127 cancer-free subjects participated in this study. Aberrant methylation at the promoters of the p16, Ras association domain family 1A (RASSF1A), fragile histidine triad (FHIT), H-cadherin, and retinoic acid receptor beta (RARbeta) genes were evaluated in the resected tumor tissues and bronchial lavage samples of NSCLC patients and in the bronchial lavage samples of cancer-free subjects by methylation-specific polymerase chain reaction. RESULTS: Of the 127 cancer-free samples, methylation was detected in 6% for p16, 13% for RARbeta, 3% for H-cadherin, 4% for RASSF1A, and 28% for FHIT. Hypermethylation of the p16, RARbeta, H-cadherin, and RASSF1A genes was not associated with patient age and smoking, whereas hypermethylation of the FHIT promoter occurred more frequently in older patients (P =.02) and was associated with exposure to tobacco smoke (P =.001). A strong correlation between age and smoking was found in patients with hypermethylation of the FHIT gene (r = 0.36; P =.03). A total of 68% of the bronchial lavage samples from the 85 NSCLC patients showed methylation of at least one of p16, RARbeta, H-cadherin, and RASSF1A genes. CONCLUSION: Our study suggests that tumor-specific methylation of the p16, RASSF1A, H-cadherin, and RARbeta genes may be a valuable biomarker for the early detection of NSCLC in bronchial lavage, and that the age-related methylation of FHIT gene in the normal bronchial epithelium is related to the exposure to tobacco smoke.     

Aberrant DNA methylation profiles of non-small cell lung cancers in a Korean population

We performed this study to investigate the aberrant methylation profile of the cancer-related genes in Korean non-small cell lung cancer (NSCLC) that previously exhibited high frequencies of methylation in Western populations. The aberrant promoter methylation of eight genes (GSTP1, p16, FHIT, APC, RASSF1A, hMLH1, hMSH2, AGT) was determined by MSP in 99 surgically resected NSCLCs and their corresponding nonmalignant lung tissues. Methylation in the tumor samples was detected at 15% for GSTP1, 22% for p16, 34% for FHIT1, 48% for APC, 40% for RASSF1A, 18% for hMLH1, 8% for hMSH2 and 21% for AGT, whereas it occurred at lower frequencies in the corresponding nonmalignant lung tissues, particularly in the p16 (1%) and RASSF1A (1%) genes. These results suggest that the methylation profiles of NSCLCs in a Korean population are similar to those in Western populations.     

Hypermethylation of multiple genes in tumor tissues and voided urine in urinary bladder cancer patients.

PURPOSE: We aimed to investigate the methylation pattern in bladder cancer and assess the diagnostic potential of such epigenetic changes in urine. EXPERIMENTAL DESIGN: The methylation status of 7 genes (RARbeta, DAPK, E-cadherin, p16, p15, GSTP1, and MGMT) in 98 cases of bladder transitional cell carcinoma and 4 cases of carcinoma in situ was analyzed by methylation-specific PCR. Twenty-two cases had paired voided urine samples for analysis. RESULTS: In transitional cell carcinoma tumor tissues, aberrant methylation was frequently detected in RARbeta (87.8%), DAPK (58.2%), E-cadherin (63.3%), and p16 (26.5%), whereas methylation of p15 (13.3%), GSTP1 (5.1%), and MGMT (5.1%) is not common. No association between methylation status and grading or muscle invasiveness was demonstrated. In 22 paired voided urine samples of bladder cancer, methylation of DAPK, RARbeta, E-cadherin, and p16 could be detected in 45.5%, 68.2%, 59.1%, and 13.6% of the cases, respectively. The sensitivity of methylation analysis (90.9%) was higher than that of urine cytology (45.5%) for cancer detection. Methylation of RARbeta(50%), DAPK (75%), and E-cadherin (50%) was also detected in carcinoma in situ. In 7 normal urothelium samples and 17 normal urine controls, no aberrant methylation was detected except for RARbeta methylation in 3 normal urothelium samples (42.9%) and 4 normal urine samples (23.5%), respectively. CONCLUSIONS: Our results demonstrated a distinct methylation pattern in bladder cancer with frequent methylation of RARbeta, DAPK, E-cadherin, and p16. Detection of gene methylation in routine voided urine using selected markers appeared to be more sensitive than conventional urine cytology.     

Aberrant promoter methylation in pleural fluid DNA for diagnosis of malignant pleural effusion

Accumulating evidence implicates epigenetic changes such as hypermethylation in carcinogenesis. We investigated whether DNA methylation of 5 tumor suppressor genes in pleural fluid samples could aid in diagnosis of malignant effusion. In samples from 47 patients with malignant pleural effusions and 34 with nonmalignant effusions, we used a methylation-specific polymerase chain reaction to detect aberrant hypermethylation of the promoters of the DNA repair gene O(6)-methylguanine-DNA methyltransferase (MGMT), p16(INK4a), ras association domain family 1A (RASSF1A), apoptosis-related genes, death-associated protein kinase (DAPK), and retinoic acid receptor beta (RARbeta). Promoter hypermethylation was associated with malignant effusion for MGMT (Odds ratio (OR) = infinity), p16(INK4a) (OR = infinity), RASSF1A (OR = 13.8; CI, 1.71-112), and RARbeta (OR = 3.17; CI, 1.10-9.11), but not for DAPK. Instead, DAPK methylation was associated with the length of smoking (p < 0.05). Patients with hypermethylation of MGMT, p16(INK4a), RASSF1A or RARbeta were 5.68 times more likely to have malignant effusions than patients without methylation (p = 0.008). Methylations per patient were more numerous for lung cancer than nonmalignant pulmonary disease (0.915 vs. 0.206, p < 0.001). Sensitivity, specificity, and positive predictive value of methylation in one or more genes for diagnosis of malignant effusion were 59.6%, 79.4%, and 80.0% respectively. In conclusion, aberrant promoter methylation of tumor suppressor genes in pleural fluid DNA could be a valuable diagnostic marker for malignant pleural effusion.     

Hypermethylation of the death-associated protein (DAP) kinase promoter and aggressiveness in stage I non-small-cell lung cancer

BACKGROUND: Death-associated protein (DAP) kinase is a serine/threonine kinase that is important in ligand-induced programmed cell death and plays an important role in lung cancer metastasis in animal models. Hypermethylation of the promoter represses the expression of the DAP kinase gene. Our purpose was to determine whether the hypermethylation status of the DAP kinase promoter influences the prognosis of non-small-cell lung cancer (NSCLC). METHODS: We retrospectively studied 135 patients with pathologic stage I NSCLC who had undergone curative surgery. Methylation-specific polymerase chain reaction was used to determine the methylation status of the DAP kinase promoter in resected specimens from patients with primary NSCLC. Statistical analyses, all two-sided, were performed to determine the prognostic effect of methylation status on various clinical parameters. RESULTS: Hypermethylation of the DAP kinase promoter was found in 59 (44%) of the 135 tumors. Patients whose tumors exhibited such hypermethylation had a statistically significantly poorer probability of overall survival at 5 years after surgery than those without such hypermethylation (.46 versus.68; P: =.007). Moreover, the groups with and without hypermethylation of the DAP kinase promoter showed a striking difference in the probability of disease-specific survival; i.e., among people who died of lung cancer-related causes specifically, the probability of 5-year survival was.56 for those with such hypermethylation and.92 for those without it (P:<.001). Multivariate analysis indicated that hypermethylation of the DAP kinase promoter is the only independent predictor for disease-specific survival among clinical and histologic parameters tested. CONCLUSIONS: Hypermethylation of the DAP kinase promoter is a common abnormality in early-stage NSCLC. This abnormality is strongly associated with survival, suggesting that DAP kinase plays an important role in determining the biologic aggressiveness of early-stage NSCLC.     

血浆中检测FHIT、p16、MGMT和RASSF1A基因甲基化在肺癌诊断中的价值

目的:探讨血浆中脆性组氨酸三连体基因(fragile histidine triad,FHIT)、p16基因、O6-甲基鸟嘌呤-DNA甲基转移酶基因(O6-methyl-guanine-DNA methyltransferase,MGMT)及信号转导通路基因(rasassociation domain family1A,RASSF1A)等抑癌基因启动子异常甲基化及其联合检测在肺癌筛查及早期诊断中的价值。方法:采用甲基化特异性PCR(methylation specifi c PCR,MSP)法,检测53例肺癌组织和对应的血浆标本以及24例肺良性病变组织中FHIT、p16、MGMT和RASSF1A4种基因启动子区甲基化状态。结果:肺癌组织中FHIT、p16、MGMT和RASSF1A基因启动子区甲基化检出率分别为39.6%(21/53)、49.1%(26/53)、35.8%(19/53)和18.9%(10/53);其对应的血浆标本中这4个基因的甲基化检出率分别为35.8%(19/53)、49.1%(26/53)、28.3%(15/53)和17.0%(9/53),两组标本甲基化检出率存在着较好的一致性(P>0.05)。24例肺良性病变组织标本和血浆标本中分别有同1例(0.04%)出现p16基因甲基化,与肺癌组比较差异有统计学意义(P<0.05)。4项指标联合检测可显著提高肺癌检测的敏感度(73.6%)和特异度(95.8%)。p16基因在血浆中甲基化检出率与患者吸烟指数有明显相关性(P<0.05)。结论:血浆中多个肺癌相关基因甲基化联合检测有望成为肺癌筛查、早期诊断简便有效的指标。     

Cohypermethylation of p16 and FHIT promoters as a prognostic factor of recurrence in surgically resected stage I non-small cell lung cancer

Despite advances in the detection and treatment of lung cancer, the prognosis for patients with lung cancer is poor, partly as a result of recurrences. We retrospectively analyzed the relationship between recurrence and survival in patients with non-small cell lung cancers (NSCLC), and the promoter methylation of p16, GSTP1, FHIT, H-cadherin, and RARbeta2 genes to identify a prognostic molecular marker associated with the recurrence of NSCLC. Methylation status from 335 paraffin blocks was determined by methylation-specific PCR. Of the 335 NSCLC samples, promoter methylation was detected in 35% for p16, 39% for RARbeta2, 42% for H-cadherin, 7% for GSTP1, and 21% for FHIT. Recurrence was observed in 39% (132 of 335) of the patients. Recurrence was significantly associated with histology (P = 0.001) and pathologic stage (P = 0.009). Hypermethylation of any single gene was not associated with recurrence in patients. However, cohypermethylation of p16 and FHIT genes in stage I NSCLCs was associated with an increased risk of recurrence [odds ratio, 6.43; 95% confidence interval (CI), 1.04-20.19; P = 0.02] and poor recurrence-free survival after surgery (hazard ratio, 2.03; 95% CI, 1.09-6.23; P = 0.02). In addition, their survival after recurrence was also 4.62 times poorer (95% CI, 1.27-16.48; P = 0.005) than for those without cohypermethylation of both genes. In conclusion, the present study suggests that cohypermethylation of p16 and FHIT genes in patients with stage I NSCLC may be a valuable biomarker for predicting the recurrence-associated prognosis of the disease.     

Promoter methylation of retinoic acid receptor beta 2 and the development of second primary lung cancers in non-small-cell lung cancer.

PURPOSE: To investigate whether the promoter hypermethylation of retinoic acid receptor beta 2 (RARbeta2) is associated with the development of second primary lung cancers (SPLCs) differentially according to smoking status in primary non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: We retrospectively analyzed the relationship between RARbeta2 methylation and the SPLC development in a total of 342 NSCLCs. The methylation status of RARbeta2 was determined by using methylation-specific polymerase chain reaction. The difference in the time to SPLC development was analyzed by using the log-rank test and the Cox proportional hazards model. The median follow-up was 4.1 years. RESULTS: SPLCs developed in 19 (5.6%) of the 342 NSCLCs, and overall incidence rate of SPLC development was 1.54 per 100 patient-years. SPLCs did not occur in 39 patients who had not smoked. After controlling for possible confounding factors, the hazard of failure for former smokers with RARbeta2 hypermethylation was about 2.87 (95% CI, 0.92 to 13.64; P =.08) times higher compared to those without RARbeta2 methylation. However, for current smokers, hypermethylation of the RARbeta2 was found to have a protective effect against the SPLC development (hazard ratio = 0.23; 95% CI, 0.11 to 0.87; P =.03). CONCLUSION: Hypermethylation of RARbeta2 promoter had a differential effect on the development of SPLCs in NSCLC, and this was dependent on smoking status. Our study suggests that a combination of retinoids and/or a demethylating agent may be effective in the prevention of SPLCs in never-smokers and former smokers with NSCLC.     

Aberrant methylation of the FHIT gene in chronic smokers with early stage squamous cell carcinoma of the lung

Fragile histidine triad (FHIT) gene plays an important role in the pathogenesis of lung cancer. However, the clinicopathological significance of CpG island hypermethylation of FHIT gene in non-small cell lung cancer (NSCLC) remains to be elucidated. We studied FHIT methylation in 254 NSCLCs in order to further understand the clinicopathological and prognostic significance of FHIT methylation in NSCLC. Methylation status of the FHIT gene was examined using Methylation-Specific PCR. All statistical analyses were two-sided, with a 5% type I error rate. Hypermethylation of the FHIT gene occurred more frequently in squamous cell carcinoma than adenocarcinoma. For 93 adenocarcinomas there was no statistically significant association between FHIT methylation and age, gender, smoking history, pathologic stage and p16 methylation. However, FHIT methylation in 125 squamous cell carcinomas was associated with exposure to tobacco smoke and p16 methylation, but not with age, gender and pathologic stage. Hypermethylation of FHIT in squamous cell carcinomas occurred more frequently in current smokers (45%) than in never-smokers (13%). FHIT methylation was significantly associated with p16 methylation in current- and ex-smokers (P = 0.02 and P = 0.01, respectively) with squamous cell carcinoma and in patients with pathologic stage I squamous cell carcinoma (P = 0.001). Patients with p16 methylation were 3.74 times [95% confidence interval (CI) = 1.62 - 7.95; P = 0.001] more likely to have FHIT methylation in squamous cell carcinoma. FHIT methylation in squamous cell carcinoma occurred at a 4.62 times (95% CI = 1.26 - 34.97; P = 0.02) higher prevalence in current smokers than in never-smokers. No prognostic effect of FHIT methylation was observed in stage I and stage II NSCLCs. In conclusion, hypermethylation of the FHIT gene did not have a prognostic significance in early stage NSCLCs. The FHIT methylation is associated with the p16 methylation and smoking in squamous cell carcinoma, suggesting that FHIT may cooperate with p16 for the development of squamous cell carcinoma of lung in individuals exposed to tobacco smoke.