We used MethyLight assays to analyze DNA methylation status of 27 genes on 49 paired cancerous and noncancerous tissue samples from non-small cell lung cancer (NSCLC) patients who underwent surgical resection. Seven genes (RARB, BVES, CDKN2A, KCNH5, RASSF1, CDH13, and RUNX) were found to be methylated significantly more frequently in tumor tissues than in noncancerous tissues. Only methylation of CCND2 and APC was frequently detected in both cancerous and noncancerous tissues, supporting the hypothesis that the methylation of these two genes is a preneoplastic change and may be associated with tobacco smoking exposure. Methylation of any one of eight genes (RASSF1, DAPK1, BVES, CDH13, MGMT, KCNH5, RARB, or CDH1) was present in 80% of NSCLC tissues but only in 14% of noncancerous tissues. Detection of methylation of these genes in blood might have utility in monitoring and detecting tumor recurrence in early-stage NSCLC after curative surgical resection.
Despite of intense research in early cancer detection, there is a lack of biomarkers for the reliable detection of malignant tumors, including non-small cell lung cancer (NSCLC). DNA methylation changes are common and relatively stable in various types of cancers, and may be used as diagnostic or prognostic biomarkers.
We performed DNA methylation profiling of samples from 48 patients with stage I NSCLC and 18 matching cancer-free lung samples using microarrays that cover the promoter regions of more than 14,500 genes. We correlated DNA methylation changes with gene expression levels and performed survival analysis.
We observed hypermethylation of 496 CpGs in 379 genes and hypomethylation of 373 CpGs in 335 genes in NSCLC. Compared to adenocarcinoma samples, squamous cell carcinoma samples had 263 CpGs in 223 hypermethylated genes and 513 CpGs in 436 hypomethylated genes. 378 of 869 (43.5%) CpG sites discriminating the NSCLC and control samples showed an inverse correlation between CpG site methylation and gene expression levels. As a result of a survival analysis, we found 10 CpGs in 10 genes, in which the methylation level differs in different survival groups.
We have identified a set of genes with altered methylation in NSCLC and found that a minority of them showed an inverse correlation with gene expression levels. We also found a set of genes that associated with the survival of the patients. These newly-identified marker candidates for the molecular screening of NSCLC will need further analysis in order to determine their clinical utility.
It remains unknown whether tobacco smoke induces DNA hypermethylation as an early event in carcinogenesis or as a late event, specific to overt cancer tissue. Using MethyLight assays, we analyzed 316 lung tissue samples from 151 cancer-free subjects (121 ever-smokers and 30 never-smokers) for hypermethylation of 19 genes previously observed to be hypermethylated in nonsmall cell lung cancers. Only APC (39%), CCND2 (21%), CDH1 (7%), and RARB (4%) were hypermethylated in >2% of these cancer-free subjects. CCND2 was hypermethylated more frequently in ever-smokers (26%) than in never-smokers (3%). CCND2 hypermethylation was also associated with increased age and upper lobe sample location. APC was frequently hypermethylated in both ever-smokers (41%) and never-smokers (30%). BVES, CDH13, CDKN2A (p16), CDKN2B, DAPK1, IGFBP3, IGSF4, KCNH5, KCNH8, MGMT, OPCML, PCSK6, RASSF1, RUNX, and TMS1 were rarely hypermethylated (<2%) in all subjects. Hypermethylation of CCND2 may reflect a smoking-induced precancerous change in the lung.
Lung cancer is the leading cause of cancer death in men and women in the United States and Western Europe. Over 160,000 Americans die of this disease every year. The five-year survival rate is 15% – significantly lower than that of other major cancers. Early detection is a key factor in increasing lung cancer patient survival. DNA hypermethylation is recognized as an important mechanism for tumor suppressor gene inactivation in cancer and could yield powerful biomarkers for early detection of lung cancer. Here we focused on developing DNA methylation markers for squamous cell carcinoma of the lung. Using the sensitive, high-throughput DNA methylation analysis technique MethyLight, we examined the methylation profile of 42 loci in a collection of 45 squamous cell lung cancer samples and adjacent non-tumor lung tissues from the same patients.
We identified 22 loci showing significantly higher DNA methylation levels in tumor tissue than adjacent non-tumor lung. Of these, eight showed highly significant hypermethylation in tumor tissue (p < 0.0001): GDNF, MTHFR, OPCML, TNFRSF25, TCF21, PAX8, PTPRN2 and PITX2. Used in combination on our specimen collection, this eight-locus panel showed 95.6% sensitivity and specificity.
We have identified 22 DNA methylation markers for squamous cell lung cancer, several of which have not previously been reported to be methylated in any type of human cancer. The top eight markers show great promise as a sensitive and specific DNA methylation marker panel for squamous cell lung cancer.
The purpose of this study was to detect the methylation of the RUNX3 gene promoter in non-small cell lung cancer (NSCLC) tissue and to explore the association of this methylation with clinical features of NSCLC. In 58 samples of NSCLC tissue and normal adjacent tissue, methylation of the RUNX3 gene promoter was measured by methylation-specific polymerase chain reaction. Correlation with clinicopathological characteristics was assessed. The results demonstrated that RUNX3 gene promoter methylation was present in 26/58 (44.8%) of NSCLC tissue samples and 10/58 (17.2%) of normal tissue samples, and that the difference was statistically significant between the two groups (χ2=10.311, p=0.001). Significantly, methylation of the RUNX3 gene promoter correlated with clinical stage, lymph node metastasis and the degree of differentiation (p<0.05) but not with age, gender, smoking history and pathological type (p>0.05). In conclusion, methylation of the RUNX3 gene promoter had a high relevance ratio in NSCLC tissue and correlated with clinical stage, lymph node metastasis and degree of differentiation; thus, this association may have clinical significance in NSCLC.
non-small cell lung cancer; promoter; methylation; RUNX3
The aim of this study was to detect methylation of the RAR-β gene in tissues from non-small cell lung cancer (NSCLC) patients. The methylation of the RAR-β gene in DNA from 80 cases with NSCLC and corresponding non-malignant tissues was tested using methylation-specific polymerase chain reaction (PCR; MSP). The results showed that the total frequency of RAR-β methylation was significantly higher in lung cancer tissues compared to the corresponding non-malignant tissues (57.5 vs. 17.5%) (P<0.01). However, no significant difference was found in various clinical stages and types of lung cancer (P>0.05). A significant difference was observed in the various pathological types (P<0.05). RAR-β gene methylation is closely correlated with the development process of NSCLC, particularly squamous cell carcinoma.
gene; methylation; non-small cell lung cancer
Hepatocellular carcinoma (HCC) is known to be associated with both HBV and HCV and HVC. While epigenetic changes have been previously reported to be associated with hepatocellular carcinoma (HCC), whether the epigenetic profile of HBC associated HCC differs from that of HCV associated HCC is unclear. We analyzed DNA methylation of ten genes (APC, CCND2, CDKN2A, GSTP1, HOXA9, RARB, RASSF1, RUNX, SFRP1, and TWIST1) using MethyLight assays on 65 archived liver tissue blocks. Three genes (APC, CCND2, and GSTP1) were frequently methylated in normal liver tissues. Five genes (APC, CDKN2A, HOXA9, RASSF1, and RUNX) were significantly more frequently methylated in malignant liver tissues than normal liver tissues. Among HCC cases, HOXA9, RASSF1 and SFRP1 were methylated more frequently in HBV positive HCC cases, while CDKN2A were significantly more frequently methylated in HCV positive HCC cases. Our data support the hypothesis that HCC resulting from different viral etiologies are associated with different epigenetic changes.
hypermethylation; HBV; HCV; hepatocellular carcinoma
Lung cancer is a major cause of death worldwide. Gene promoter methylation is a major inactivation mechanism of tumor-related genes, some of which can be served as a biomarker for early diagnosis and prognosis evaluation of lung cancer.
We determined the promoter methylation of 6 genes using quantitative methylation-specific PCR (Q-MSP) technique in 96 clinically well-characterized non-small cell lung cancer (NSCLC).
Highly frequent promoter methylation was found in NSCLC. With 100% diagnostic specificity, high sensitivity, ranging from 44.9 to 84.1%, was found for each of the 6 genes. Our data also showed that promoter methylation was closely associated with histologic type. Most of genes were more frequently methylated in squamous cell carcinomas (SCC) compared to adenocarcinomas (ADC). Moreover, promoter methylation significantly increased the risk of pleural indentation in NSCLC.
Our findings provided evidences that multiple genes were aberrantly methylated in lung tumorigenesis, and demonstrated the promoter methylation was closely associated with clinicopathologic characteristics of NSCLC. More importantly, we first revealed promoter methylation may be served as a potentially increased risk factor for pleural indentation of NSCLC patients.
WNT7A (wingless-type MMTV integration site family, member 7A) is a known tumor suppressor gene of non-small cell lung carcinomas (NSCLC) and is frequently inactivated due to CpG-island hypermethylation in human cancers. The members of WNT family are involved in cell signaling and play crucial roles in cancer development. In the present work hypermethylation of the WNT7A gene was detected in 66% (29/44) of analyzed clear cell renal cell carcinomas (RCCs) using methyl-specific PCR (MSP). Moreover, bisulfite sequencing confirmed intensive hypermethylation of the 5′-CpG island of the WNT7A gene. Methylation analysis revealed positive correlations between tumor stage, Fuhrman nuclear grade and WNT7A hypermethylation. Additionally, restoration of WNT7A gene expression in the A498 cell line by 5-aza-2′-deoxycytidine treatment confirmed a direct contribution of hypermethylation in silencing of the WNT7A gene. High frequency of loss of heterozygosity (LOH) was demonstrated on chromosome 3p25 in regions surrounding the WNT7A gene. The frequent down-regulation of WNT7A gene expression was detected in 88% (15/17) of clear cell RCCs. We have also shown that the WNT7A gene possesses tumor suppression function by colony-formation and cell proliferation assays in RCC cell lines. In summary, the WNT7A gene is inactivated by genetic/epigenetic alterations in clear cell RCC and demonstrates tumor suppressor properties.
In our previous study, we attempted to develop a tool for the early diagnosis of non-small cell lung cancer (NSCLC) using DNA methylation biomarkers. With the aim of improving the diagnostic potential by optimizing the composition of the target set, in this study, 13 candidate genes (ACTA1, AIDH1A2, CBX8, CDH8, EVX1, MGC16275, NEUROG1, NEUROG2, NID2, OTX2OS1, PGAM2, PHOX2B and TOX) were analyzed by methylation-specific PCR to determine the methylation status of each gene in 5 NSCLC cell lines and in lung tissue samples from 15 healthy volunteers, 103 stage I NSCLC patients and 26 non-cancerous control patients. Results showed that NEUROG2 and NID2 were hypermethylated in stage I NSCLC tissues (31.07 and 46.60%, respectively) and unmethylated in normal lung tissues (0/15) and non-cancerous tissues (0/26). Following recombination, an optimized 5-gene panel (NEUROG2, NID2, RASSF1A, APC and HOXC9) achieved a sensitivity of 91.26% with a specificity of 84.62% in the detection of stage I NSCLC. The optimized 5-gene panel greatly improved the diagnostic power for stage I NSCLC.
NEUROG2; NID2; DNA methylation; non-small cell lung cancer; stage I
Lung cancer has become the top killer among malignant tumors in China and is significantly associated with somatic genetic alterations. We performed exome sequencing of 14 non–small cell lung carcinomas (NSCLCs) with matched adjacent normal lung tissues extracted from Chinese patients. In addition to the lung cancer–related genes (TP53, EGFR, KRAS, PIK3CA, and ROS1), this study revealed “novel” genes not previously implicated in NSCLC. Especially, matrix-remodeling associated 5 was the second most frequently mutated gene in NSCLC (first is TP53). Subsequent Sanger sequencing of matrix-remodeling associated 5 in an additional sample set consisting of 52 paired tumor-normal DNA samples revealed that 15% of Chinese NSCLCs contained somatic mutations in matrix-remodeling associated 5. These findings, together with the results from pathway analysis, strongly indicate that altered extracellular matrix-remodeling may be involved in the etiology of NSCLC.
While qualitative analysis of methylation has been reviewed, the quantitative analysis of methylation has rarely been studied. We evaluated the methylation status of CDKN2A, RARβ, and RASSF1A promoter regions in non-small cell lung carcinomas (NSCLCs) by using pyrosequencing. Then, we evaluated the association between methylation at the promoter regions of these tumor suppressor genes and the clinicopathological parameters of the NSCLCs.
We collected tumor tissues from a total of 53 patients with NSCLCs and analyzed the methylation level of the CDKN2A, RARβ, and RASSF1A promoter regions by using pyrosequencing. In addition, we investigated the correlation between the hypermethylation of CDKN2A and the loss of p16INK4A immunoexpression.
Hypermethylation of CDKN2A, RARβ, and RASSF1A promoter regions were 16 (30.2%), 22 (41.5%), and 21 tumors (39.6%), respectively. The incidence of hypermethylation at the CDKN2A promoter in the tumors was higher in undifferentiated large cell carcinomas than in other subtypes (p=0.002). Hyperrmethylation of CDKN2A was significantly associated with p16INK4A immunoexpression loss (p=0.045). With regard to the clinicopathological characteristics of NSCLC, certain histopathological subtypes were found to be strongly associated with the loss of p16INK4A immunoexpression (p=0.016). Squamous cell carcinoma and undifferentiated large cell carcinoma showed p16INK4A immunoexpression loss more frequently. The Kaplan-Meier survival curves analysis showed that methylation level and patient survival were barely related to one another.
We quantitatively analyzed the promoter methylation status by using pyrosequencing. We showed a significant correlation between CDKN2A hypermethylation and p16INK4A immunoexpression loss.
DNA Methylation; Genes, p16; RASSF1 Protein, Human; Receptors, Retinoic Acid; Sequence Analysis, DNA; Carcinoma, Non-Small Cell Lung
High serum carcinoembryonic antigen (CEA) levels have been reported to be associated with poor prognosis in non-small cell lung cancer (NSCLC), while the prognostic role of tumor CEA expression remains to be defined. The present study investigated the expression of tumor CEA in stage IB NSCLC, and correlated it with clinicopathological features and prognosis.
Patients and methods
Immunohistochemistry for tumor CEA was assessed in the specimens of 183 patients with stage IB NSCLC. Receiver-operating characteristic (ROC) curve analysis was used to determine the cut-off score for tumor positivity.
High CEA expression was detected more frequently in adenocarcinomas (72.2%) and other NSCLCs (69.0%) than in squamous cell carcinomas (25.4%, P<0.001). Both univariate and multivariate analysis indicated that tumor CEA was an independent prognostic factor for overall and disease-free survival (P<0.05).
Elevated expression of tumor CEA may be an adverse prognostic indicator in stages IB NSCLC.
Non-small cell lung cancer; carcinoembryonic antigen; prognosis; receiver operating characteristic curve
O6-methylguanine-DNA methyltransferase (MGMT) is one of most important DNA repair enzyme against common carcinogens such as alkylate and tobacco. Aberrant promoter methylation of the gene is frequently observed in non-small cell lung cancer (NSCLC). However, the importance of epigenetic inactivation of the gene in NSCLC published in the literature showed inconsistence. We quantified the association between MGMT promoter methylation and NSCLC using a meta-analysis method.
We systematically reviewed studies of MGMT promoter methylation and NSCLC in PubMed, EMBASE, Ovid, ISI Web of Science, Elsevier and CNKI databases and quantified the association between MGMT promoter methylation and NSCLC using meta-analysis method. Odds ratio (OR) and corresponding 95% confidence interval (CI) were calculated to evaluate the strength of association. Potential sources of heterogeneity were assessed by subgroup analysis and meta-regression.
A total of 18 studies from 2001 to 2011, with 1, 160 tumor tissues and 970 controls, were involved in the meta-analysis. The frequencies of MGMT promote methylation ranged from 1.5% to 70.0% (median, 26.1%) in NSCLC tissue and 0.0% to 55.0% (median, 2.4%) in non-cancerous control, respectively. The summary of OR was 4.43 (95% CI: 2.85, 6.89) in the random-effects model. With stratification by potential source of heterogeneity, the OR was 20.45 (95% CI: 5.83, 71.73) in heterogeneous control subgroup, while it was 4.16 (95% CI: 3.02, 5.72) in the autologous control subgroup. The OR was 5.31 (95% CI: 3.00, 9.41) in MSP subgroup and 3.06 (95% CI: 1.75, 5.33) in Q-MSP subgroup.
This meta-analysis identified a strong association between methylation of MGMT gene and NSCLC. Prospective studies should be required to confirm the results in the future.
Epigenetic analysis shows that many genes that suppress malignancy are silenced by aberrant DNA methylation in lung cancer. Many of these genes are interesting targets for reactivation by the inhibitor of DNA methylation, decitabine (5-aza-2′-deoxycytidine, DAC). A pilot study on intense dose DAC showed promising results in patients with metastatic non-small cell lung cancer (NSCLC). However, subsequent clinical studies using low dose DAC were not very effective against NSCLC and interest in this therapy diminished. Recently, interesting responses were observed in a patient with NSCLC following treatment with a combination of the related inhibitor of DNA methylation, 5-azacytidine, and an inhibitor of histone deacetylation. This finding has generated a renewed interest in the epigenetic therapy of lung cancer. Preclinical studies indicate that DAC has remarkable chemotherapeutic potential for tumor therapy. This epigenetic agent has a delayed and prolonged epigenetic action on tumor cells. This delayed action should be taken into consideration in the design and evaluation of clinical studies on DAC. Future research should be directed at finding the optimal dose-schedule of de DAC for the treatment of NSCLC.
non-small cell lung cancer; chemotherapy; decitabine; epigenetics
Systemic methylation changes may be a diagnostic marker for tumor development or prognosis. Here, we investigate the relationship between gene methylation in lung tumors relative to normal lung tissue, and whether DNA methylation changes can be detected in paired blood samples.
Material and methods
Sixty five patients were enrolled in a surgical case series of non-small cell lung cancer (NSCLC) at a single institution. Using bisulfite pyrosequencing, CpG methylation was quantified at five genes (RASSF1A, CDH13, MGMT, ESR1 and DAPK) in lung tumor, pathologically normal lung tissue, and circulating blood from enrolled cases.
The analyses of methylation in tumors compared to normal lung tissue identified higher methylation of CDH13, RASSF1A, and DAPK genes, while ESR1 and MGMT methylation did not differ significantly between these tissue types. We then examined whether the three aberrantly methylated genes could be detected in blood. The difference in methylation observed in tumors was not reflected in methylation status of matching blood samples, indicating a low feasibility of detecting lung cancer by analyzing these genes in a blood-based test. Lastly we probed whether tumor methylation was associatied with clinical and demographic characteristics. Histology and gender were associated with methylation at the CDH13 gene, while stage was associated with methylation at MGMT.
Our results show higher methylation of RASSF1A, CDH13, and DAPK genes in lung tumors compared to normal lung. The lack of reflection of these methylation changes in blood samples from patients with NSCLC indicate their poorly suitability for a screening test.
methylation; non-small cell lung cancer; CDH13; MGMT; clinicopathological characteristics
RNA binding motif 5 (RBM5) is a tumor suppressor gene that modulates apoptosis through the regulation of alternative splicing of apoptosis-related genes. This study aimed to detect RBM5 expression in non-small cell lung cancer (NSCLC) and to associate RBM5 expression with clinicopathological data from NSCLC patients and EGFR and KRAS expression to better understand the potential role of RBM5 in NSCLC.
Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were performed to detect expression of mRNA and protein, respectively, of RBM5, EGFR and KRAS in 120 paired non-tumor and tumor samples of NSCLC.
The data showed that expression of RBM5 mRNA and protein was significantly reduced in NSCLC compared to normal tissues, whereas expression of both EGFR and KRAS genes was increased in NSCLC compared to normal tissues. Furthermore, the reduced RBM5 protein expression correlated with smoking status, tumor stage and lymph node metastasis of NSCLC, while overexpression of EGFR and KRAS proteins correlated with tumor stage and lymph node metastasis of NSCLC. Overexpression of KRAS protein was more frequent in smokers with NSCLC. In addition, expression of RBM5 mRNA and protein was negatively correlated with expression of EGFR and KRAS mRNA and protein in NSCLC tissues.
This study suggests further evaluation of RBM5 expression is warranted for use of RBM5 as a biomarker for NSCLC patients.
NSCLC; RBM5; EGFR; KRAS; carcinogenesis
While there is no reliable serum biomarker for the diagnosis and monitoring of patients with gastric cancer, we tested the potential diagnostic and prognostic values of detecting methylation changes in the serum of gastric cancer patients. DNA was extracted from the pretherapeutic serum of 60 patients with confirmed gastric adenocarcinoma and 22 age-matched noncancer controls. Promoter hypermethylation in 10 tumour-related genes (APC, E-cadherin, GSTP1, hMLH1, MGMT, p15, p16, SOCS1, TIMP3 and TGF-beta RII) was determined by quantitative methylation-specific PCR (MethyLight). Preferential methylation in the serum DNA of gastric cancer patients was noted in APC (17%), E-cadherin (13%), hMLH1 (41%) and TIMP3 (17%) genes. Moreover, patients with stages III/IV diseases tended to have higher concentrations of methylated APC (P=0.08), TIMP3 (P=0.005) and hMLH1 (P=0.03) in the serum. In all, 33 cancers (55%) had methylation detected in the serum in at least one of these four markers, while three normal subjects had methylation detected in the serum (specificity 86%). The combined use of APC and E-cadherin methylation markers identified a subgroup of cancer patients with worse prognosis (median survival 3.3 vs 16.1 months, P=0.006). These results suggest that the detection of DNA methylation in the serum may carry both diagnostic and therapeutic values in gastric cancer patients.
gastric cancer; promoter hypermethylation; tumour suppressor genes; oncogenes
It is well known that genetic alternation of epidermal growth factor receptor (EGFR) plays critical roles in tumorgenesis of lung cancer and can predict outcome of non-small-cell lung cancer treatment, especially the EGFR tyrosine-kinase inhibitors (EGFR-TKIs) therapy. However, it is unclear whether epigenetic changes such as DNA methylation involve in the response to the EGFR-TKI therapy.
Tumor samples from 155 patients with stages IIIB to IV NSCLC who received EGFR-TKI therapy were analyzed for DNA methylation status of Wnt antagonist genes, including SFRP1, SFRP2, SFRP5, DKK3, WIF1, and APC, using methylation specific PCR (MSP) method. EGFR mutations detections were performed in the same tissues samples using Denaturing High Performance Liquid Chromatography (DHPLC).
We found that Wnt antagonists tend to methylate simultaneously. Methylation of sFRP1 and sFRP5 are reversely correlated with EGFR mutation (P = 0.005, P = 0.011). However, no correlations of methylations of other Wnt antagonist genes with EGFR mutation were found. The patients with methylated SFRP5 have a significant shorter progression free survival than those with unmethylated SFRP5 in response to EGFR-TKI treatment (P = 0.002), which is independent of EGFR genotype.
Patients with unmethylated SFRP5 are more likely to benefit from EGFR-TKI therapy.
DNA methylation; EGFR-TKI; Wnt antagonists; Non-small cell lung cancer
Lung cancer is the number one cancer killer of both men and women in the United States. Three quarters of lung cancer patients are diagnosed with regionally or distantly disseminated disease; their 5-year survival is only 15%. DNA hypermethylation at promoter CpG islands shows great promise as a cancer-specific marker that would complement visual lung cancer screening tools such as spiral CT, improving early detection. In lung cancer patients, such hypermethylation is detectable in a variety of samples ranging from tumor material to blood and sputum. To date the penetrance of DNA methylation at any single locus has been too low to provide great clinical sensitivity. We used the real-time PCR-based method MethyLight to examine DNA methylation quantitatively at twenty-eight loci in 51 primary human lung adenocarcinomas, 38 adjacent non-tumor lung samples, and 11 lung samples from non-lung cancer patients.
We identified thirteen loci showing significant differential DNA methylation levels between tumor and non-tumor lung; eight of these show highly significant hypermethylation in adenocarcinoma: CDH13, CDKN2A EX2, CDX2, HOXA1, OPCML, RASSF1, SFPR1, and TWIST1 (p-value << 0.0001). Using the current tissue collection and 5-fold cross validation, the four most significant loci (CDKN2A EX2, CDX2, HOXA1 and OPCML) individually distinguish lung adenocarcinoma from non-cancer lung with a sensitivity of 67–86% and specificity of 74–82%. DNA methylation of these loci did not differ significantly based on gender, race, age or tumor stage, indicating their wide applicability as potential lung adenocarcinoma markers. We applied random forests to determine a good classifier based on a subset of our loci and determined that combined use of the same four top markers allows identification of lung cancer tissue from non-lung cancer tissue with 94% sensitivity and 90% specificity.
The identification of eight CpG island loci showing highly significant hypermethylation in lung adenocarcinoma provides strong candidates for evaluation in patient remote media such as plasma and sputum. The four most highly ranked loci, CDKN2A EX2, CDX2, HOXA1 and OPCML, which show significant DNA methylation even in stage IA tumor samples, merit further investigation as some of the most promising lung adenocarcinoma markers identified to date.
Aim of the study
Metastases of non-small cell lung cancer (NSCLC) into pleura disqualify a patient from surgery and present a bad prognostic index. The aim of the study was to find out whether washing out the pleural cavity in such cases and examining obtained washings for presence of cancer cells will help to detect early NSCLC metastases into pleura, and also whether negative results of the cytology determine whether hypermethylation of these genes will increase the sensitivity of this examination.
Material and methods
The study consisted of the examination of 76 patients, including 59 operated on for NSCLC and 17 operated on for other reasons. Pleural washing fluid collected during the surgery was subjected to cytological examination as well as examined to determine the presence of promoter region hypermethylation of p16 and MGMT genes.
Positive cytological results of pleural lavage were confirmed in 4 persons (7%) with NSCLC. The presence of promoter region hypermethylation of one or both examined genes was found in 3 patients (18%) in the control group and in 47 (80%) in the study group. Sex, occupational exposure, smoking cigarettes, and NSCLC histological type did not have an influence on the presence of cancer cells or hypermethylation in the pleural lavage fluid. Positive cytology results were more frequent at the T4 stage of NSCLC. Hypermethylation was more frequent in the research group (p < 0.01). Cancer cells and hypermethylation did not occur more frequently in pleural lavage fluid of patients with metastases into pleura.
The cytological examination and promoter region hypermethylation assessment of the p16 gene and MGMT gene in pleural lavage cells do not allow one to detect early metastasis of NSCLC into pleura.
lung cancer; pleura; cytology; DNA methylation; p16 gene; O(6)-methylguanine-DNA methyltransferase
Frequencies of EGFR and KRAS mutations in non-small cell lung cancer (NSCLC) have predominantly been determined in East Asian and North American populations, showing large differences between these populations. The aim of the present study was to determine the frequency of EGFR and KRAS mutations in NSCLC in the West European Dutch population in primary carcinomas and different metastatic locations.
EGFR (exons 19, 20 and 21) and KRAS (exons 2 and 3) mutation test results of NSCLC samples of patients in 13 hospitals were collected. The tests were performed on paraffin-embedded tissue or cytological material of primary and metastatic lung carcinomas.
EGFR mutations were detected in 71/778 (9.1 %) tested patients; in 66/620 (10.6 %) adenocarcinomas. EGFR mutations were significantly more often detected in female than in male patients (13.4 % vs. 5.5 %, p < 0.001). KRAS mutations were found in 277 out of 832 (33.3 %) tested patients; in 244/662 (36.9 %) adenocarcinomas. A significantly increased frequency of EGFR mutations was observed in patients with malignant pleural/pericardial effusions (26.5 %; odds ratio (OR) 2.80, 95 % confidence interval (CI) 1.22–6.41), whereas the frequency of KRAS mutations was significantly decreased (18.8 %; OR 0.35, 95 % CI 0.14–0.86).
In the investigated Dutch cohort, patients with malignant pleural/pericardial effusion of lung adenocarcinoma have an increased frequency of EGFR mutations. The overall frequency of EGFR mutations in lung adenocarcinomas in this West European population is within the frequency range of North American and South European populations, whereas KRAS mutation frequency is higher than in any population described to date.
Non-small cell lung cancer; Adenocarcinoma; EGFR; KRAS; Metastasis; Pleural effusion
AIM: To investigate the feasibility of detecting hypermethylated secreted frizzled-related protein 2 (SFRP2) gene in fecal DNA as a non-invasive screening tool for colorectal cancer (CRC).
METHODS: Fluorescence-based real-time PCR assay (MethyLight) was performed to analyze SFRP2 gene promoter methylation status in a blinded fashion in tumor tissues and in stool samples taken from 69 CRC patients preoperatively and at the 9th postoperative day, 34 patients with adenoma ≥ 1 cm, 26 with hyperplastic polyp, and 30 endoscopically normal subjects. Simultaneously the relationship between hypermethylation of SFRP2 gene and clinicopathological features was analyzed.
RESULTS: SFRP2 gene was hypermethylated in 91.3% (63/69) CRC, 79.4% (27/34) and 53.8% (14/26) adenoma and hyperplastic polyp tissues, and in 87.0% (60/69), 61.8% (21/34) and 42.3% (11/26) of corresponding fecal samples, respectively. In contrast, no methylated SFRP2 gene was detected in mucosal tissues of normal controls, while two cases of matched fecal samples from normal controls were detected with hypermethylated SFRP2. A significant decrease (P < 0.001) in the rate of hypermethylated SFRP2 gene was detected in the postoperative (8.7%, 6/69) fecal samples as compared with the preoperative fecal samples (87%, 60/69) of CRC patients. Moreover, no significant associations were observed between SFRP2 hypermethylation and clinicopathological features including sex, age, tumor stage, site, lymph node status and histological grade, etc.
CONCLUSION: Hypermethylation of SFRP2 gene in fecal DNA is a novel molecular biomarker of CRC and carries a high potential for the remote detection of CRC and premalignant lesions as noninvasive screening method.
Colorectal cancer; Secreted frizzled-related protein 2; Feces; Methylation; Screening
Aberrant methylation of promoter DNA and transcriptional repression of specific tumor suppressor genes play an important role in carcinogenesis. Recently, many studies have investigated the association between cigarette smoking and p16INK4α gene hypermethylation in lung cancer, but could not reach a unanimous conclusion.
Methods and Findings
Nineteen cross-sectional studies on the association between cigarette smoking and p16INK4α methylation in surgically resected tumor tissues from non-small cell lung carcinoma (NSCLC) patients were identified in PubMed database until June 2011. For each study, a 2×2 cross-table was extracted. In total, 2,037 smoker and 765 nonsmoker patients were pooled with a fixed-effects model weighting for the inverse of the variance. Overall, the frequency of p16INK4α hypermethylation was higher in NSCLC patients with smoking habits than that in non-smoking patients (OR = 2.25, 95% CI = 1.81–2.80). The positive association between cigarette smoking and p16INK4α hypermethylation was similar in adenocarcinoma and squamous-cell carcinoma. In the stratified analyses, the association was stronger in Asian patients and in the studies with larger sample sizes.
Cigarette smoking is positively correlated to p16INK4α gene hypermethylation in NSCLC patients.
The purpose of this study was to identify key genetic pathways involved in non-small cell lung cancer (NSCLC) and understand their role in tumor progression. We performed a genome wide scanning using paired tumors and corresponding 16 mucosal biopsies from four follow-up lung cancer patients on Affymetrix 250K-NSpI array platform. We found that a single gene SH3GL2 located on human chromosome 9p22 was most frequently deleted in all the tumors and corresponding mucosal biopsies. We further validated the alteration pattern of SH3GL2 in a substantial number of primary NSCLC tumors at DNA and protein level. We also overexpressed wild-type SH3GL2 in three NSCLC cell lines to understand its role in NSCLC progression. Validation in 116 primary NSCLC tumors confirmed frequent loss of heterozygosity of SH3GL2 in overall 51 % (49/97) of the informative cases. We found significantly low (p=0.0015) SH3GL2 protein expression in 71 % (43/60) primary tumors. Forced over-expression of wild-type (wt) SH3GL2 in three NSCLC cell lines resulted in a marked reduction of active epidermal growth factor receptor (EGFR) expression and an increase in EGFR internalization and degradation. Significantly decreased in vitro (p=0.0015–0.030) and in vivo (p=0.016) cellular growth, invasion (p=0.029–0.049), and colony formation (p=0.023–0.039) were also evident in the wt-SH3GL2-transfected cells accompanied by markedly low expression of activated AKT(Ser473), STAT3 (Tyr705), and PI3K. Downregulation of SH3GL2 interactor USP9X and activated β-catenin was also evident in the SH3GL2-transfected cells. Our results indicate that SH3GL2 is frequently deleted in NSCLC and regulates cellular growth and invasion by modulating EGFR function.
Single nucleotide polymorphism array; Lung cancer; SH3GL2; Deletion