Combined effects methylation of FHIT, RASSF1A and RARβ genes on non-small cell lung cancer in the Chinese population

Promoter hypermethylation of RAR-β tumor suppressor gene in gastric carcinoma: Association with histological type and clinical outcomes

BACKGROUND

While gastric cancer is a common cancer in the world and Iran, its molecular mechanisms are not fully understood as yet. Epigenetic modifications can lead to alteration of gene expression and development of tumorigenesis mechanisms.

METHODS

To clarify the difference in DNA methylation pattern of histological types in gastric carcinoma, CpG islands in the promoters of retinoic acid receptor β gene (RAR-β) was studied using methylation-specific PCR.

RESULTS

In gastric cancer tissues, hypermethylation frequency of RAR-β gene was respectively 61 and 33% for diffuse and intestinal type. In diffuse type, hypermethylation of RAR-β has been significantly associated with invasion (P= 0.007), differentiation (P= 0.033) and location (P= 0.012) of the tumor. However, hypermethylation of RAR-β correlated only with tumor size (P= 0.029) in intestinal type. For adjacent non-tumor samples, hypermethylation of RAR-β was not detected and there was no significant association between age of diagnosis and hypermethylation of RAR-β in both types of gastric cancer.

CONCLUSIONS

These results support previous findings denoting a distinct profile of promoter hypermethylation status in the development of the intestinal and diffuse type of gastric carcinoma and the process of the tumorigenesis in these subtypes of gastric cancer is different from each other.

Gene methylation as a powerful biomarker for detection and screening of non-small cell lung cancer in blood

DNA methylation has been reported to become a potential powerful tool for cancer detection and diagnosis. However, the possibilities for the application of blood-based gene methylation as a biomarker for non-small cell lung cancer (NSCLC) detection and screening remain unclear. Hence, we performed this meta-analysis to evaluate the value of gene methylation detected in blood samples as a noninvasive biomarker in NSCLC. A total of 28 genes were analyzed from 37 case-control studies. In the genes with more than three studies, we found that the methylation of P16, RASSF1A, APC, RARβ, DAPK, CDH13, and MGMT was significantly associated with risks of NSCLC. The methylation statuses of P16, RASSF1A, APC, RARβ, DAPK, CDH13, and MGMT were not linked to age, gender, smoking behavior, and tumor stage and histology in NSCLC. Therefore, the use of the methylation status of P16, RASSF1A, APC, RARβ, DAPK, CDH13, and MGMT could become a promising and powerful biomarker for the detection and screening of NSCLC in blood in clinical settings. Further large-scale studies with large sample sizes are necessary to confirm our findings in the future.

Association between Retinoic acid receptor-β hypermethylation and NSCLC risk: a meta-analysis and literature review

Emerging evidence indicates that Retinoic acid receptor-β (RARβ) is a tumor suppressor in many types of tumor. However, whether or not RARβ is a risk factor and is correlated to clinicopathological characteristics of non-small cell lung cancer (NSCLC) remains unclear. In this report, we performed a meta-analysis to determine the effects of RARβ hypermethylation on the incidence of NSCLC and clinicopathological characteristics in human NSCLC patients. Final valuation and analysis of 1780 cancer patients from 16 eligible studies was performed. RARβ hypermethylation was found to be significantly higher in NSCLC than in normal lung tissue, the pooled OR from 7 studies including 646 NSCLC and 580 normal lung tissues, OR = 6.05, 95% CI = 3.56-10.25, p<0.00001. RARβ hypermethylation was significantly higher in adenocarcinoma (AC) compared to squamous cell carcinoma (SCC), pooled OR is 0.68 (95% CI = 0.52-0.89, p = 0.005). RARβ hypermethylation was also found to occur significantly higher in smoker (n = 232) than non-smoker (n = 213) (OR = 2.46, 95% CI = 1.54-3.93, p = 0.0002). Our results indicate that RARβ hypermethylation correlates well with an increased risk in NSCLC patients. RARβ geneinactivation caused by RARβ methylation contributes the NSCLC tumorigenesis and may serve as a potential risk factor, diagnostic marker and drug target of NSCLC.

Quantitative assessment of the diagnostic role of FHIT promoter methylation in non-small cell lung cancer

Aberrant methylation of CpG islands acquired in promoter regions plays an important role in carcinogenesis. Accumulated evidence demonstrates FHIT gene promoter hyper-methylation is involved in non-small cell lung cancer (NSCLC). To test the diagnostic ability of FHIT methylation status on NSCLC, thirteen studies, including 2,119 samples were included in our meta-analysis. Simultaneously, four independent DNA methylation datasets from TCGA and GEO database were analyzed for validation. The pooled odds ratio of FHIT promoter methylation in cancer samples was 3.43 (95% CI: 1.85 to 6.36) compared with that in controls. In subgroup analysis, significant difference of FHIT gene promoter methylation status in NSCLC and controls was found in Asians but not in Caucasian population. In validation stage, 950 Caucasian samples, including 126 paired samples from TCGA, 568 cancer tissues and 256 normal controls from GEO database were analyzed, and all 8 CpG sites near the promoter region of FHIT gene were not significantly differentially methylated. Thus the diagnostic role of FHIT gene in the lung cancer may be relatively limited in the Caucasian population but useful in the Asians.

The clinical value of aberrant epigenetic changes of DNA damage repair genes in human cancer

The stability and integrity of the human genome are maintained by the DNA damage repair (DDR) system. Unrepaired DNA damage is a major source of potentially mutagenic lesions that drive carcinogenesis. In addition to gene mutation, DNA methylation occurs more frequently in DDR genes in human cancer. Thus, DNA methylation may play more important roles in DNA damage repair genes to drive carcinogenesis. Aberrant methylation patterns in DNA damage repair genes may serve as predictive, diagnostic, prognostic and chemosensitive markers of human cancer. MGMT methylation is a marker for poor prognosis in human glioma, while, MGMT methylation is a sensitive marker of glioma cells to alkylating agents. Aberrant epigenetic changes in DNA damage repair genes may serve as therapeutic targets. Treatment of MLH1-methylated colon cancer cell lines with the demethylating agent 5′-aza-2′-deoxycytidine induces the expression of MLH1 and sensitizes cancer cells to 5-fluorouracil. Synthetic lethality is a more exciting approach in patients with DDR defects. PARP inhibitors are the most effective anticancer reagents in BRCA-deficient cancer cells.

Clinicopathological significance and a potential drugtarget of RARβ in non-small-cell lung carcinoma: a meta-analysis and a systematic review

Lung cancer is the leading cause of cancer-related mortality in men worldwide. Aberrant RARβ promoter methylation has been frequently investigated in non-small-cell lung carcinoma (NSCLC), the most common form of lung cancer. The aim of present study was to carry out a meta-analysis and a systematic review to evaluate clinicopathological significance of RARβ promoter hypermethylation in NSCLC. A systematic literature search was carried out. The data were extracted and assessed by two reviewers independently. The Cochrane software Review Manager 5.2 was used to conduct the review. Odds ratios (ORs) with 95% corresponding confidence intervals (CIs) were calculated. A total of 18 relevant articles were available for meta-analysis which included 1,871 participants. The frequency of RARβ hypermethylation was significantly increased in NSCLC than in nonmalignant lung tissue, and the pooled OR was 5.69 (P<0.00001). RARβ hypermethylation was significantly more frequently observed in adenocarcinoma (AC) than in squamous cell carcinoma (SCC), and the pooled OR was 1.47 (P=0.005). Hypermethylation of RARβ gene in NSCLC was 2.46 times higher in smoking than in nonsmoking individuals, and the pooled OR was 2.46 (P=0.0002). RARβ hypermethylation rate was not significantly correlated with stage of the disease and sex. RARβ gene methylation status was not associated with prognosis of patients with NSCLC. In conclusion, RARβ promoter hypermethylation significantly increased in NSCLC than in non-neoplastic lung tissue and is predominant in AC, suggesting that RARβ methylation contributes to the development of NSCLC, especially AC. RARβ gene is a potential novel target for development of personalized therapy in patients with NSCLC, and is promising in restoration of retinoic acid-target gene induction via demethylation of RARβ1' promoter.

Aberrant Methylation of RASSF1A gene Contribute to the Risk of Renal Cell Carcinoma: a Meta-Analysis

The aim of this study was to assess the diagnostic value of RASSF1A methylation in renal cell carcinoma. Systematically search were performed using the Pubmed, ProQest and Web of Science for all articles on the association between RASSF1A methylation and renal cell carcinoma before 15 April 2015. After the filtration, 13 studies involving 677 cases and 497 controls met our criteria. Our meta-analysis suggested that hypermethylation of RASSF1A gene was associated with the increased risk of RCC(OR:4.14, 95%CI:1.06-16.1). Stratified analyses showed a similar risk in qualitative detection method(OR:28.4, 95%CI:10.2-79.6), body fluid sample(OR:12.8, 95%CI:5.35-30.8), and American(OR:10.5, 95%CI:1.97-55.9). Our result identified that RASSF1A methylation had a strong potential in prediction the risk of Renal cell carcinoma.

The clinicopathological significance and ethnic difference of FHIT hypermethylation in non-small-cell lung carcinoma: a meta-analysis and literature review

Emerging evidence indicates that FHIT is a candidate tumor suppressor in many types of tumors including non-small-cell lung carcinoma (NSCLC). However, the prognostic value and correlation between FHIT hypermethylation and clinicopathological characteristics of NSCLC remains unclear. In this report, we performed a meta-analysis to evaluate the effects of FHIT hypermethylation on the incidence of NSCLC and clinicopathological characteristics of human NSCLC patients. Final analysis of 1,801 NSCLC patients from 18 eligible studies was performed. FHIT hypermethylation was found to be significantly higher in NSCLC than in normal lung tissue. The pooled odds ratio (OR) from ten studies included 819 NSCLC and 792 normal lung tissues (OR =7.51, 95% confidence interval [CI] =2.98-18.91, P<0.0001). Subgroup analysis based on ethnicity implied that FHIT hypermethylation level was higher in NSCLC tissues than in normal tissues in both Caucasians (P=0.02) and Asians (P<0.0001), indicating that the difference in Asians was much more significant. FHIT hypermethylation was also correlated with sex status, smoking status, as well as pathological types. In addition, patients with FHIT hypermethylation had a lower survival rate than those without (hazard ratio =1.73, 95% CI =1.10-2.71, P=0.02). The results of this meta-analysis suggest that FHIT hypermethylation is associated with an increased risk and poor survival in NSCLC patients. FHIT hypermethylation, which induces the inactivation of FHIT gene, plays an important role in the carcinogenesis and clinical outcome and may serve as a potential diagnostic marker and drug target of NSCLC.

[Meta-analysis of the Association between RASSF1A Gene Promoter Methylation and Non-small Cell Lung Cancer]

BACKGROUND AND OBJECTIVE

The CpG island aberrant promoter methylation in the tumor suppressor gene region plays an important role in the process of tumorigenesis. Relevant evidence shows that the promoter methylation of RAS association domain family 1A (RASSF1A) gene, a tumor suppressor gene, has a close relationship with non-small cell lung cancer (NSCLC) development; therefore, RASSF1A may be a potential NSCLC biomarker. This paper discussed and summarized the relationship between RASSF1A gene promoter methylation frequency and NSCLC through meta-analysis.

METHODS

By searching Medline, EMBASE, CNKI, and Wanfang database, we selected and collected the published articles regarding RASSF1A gene promoter methylation and NSCLC risk according to the marked inclusion and exclusion criteria. Through meta-analysis, combined odds ratio (OR) and 95% confidence interval (CI) data were used to analyze the RASSF1A gene promoter methylation and NSCLC relationship.

RESULTS

A total of 23 articles were utilized in this study. Results indicated that the RASSF1A gene promoter methylation rate was 41.50% (95%CI: 34%-49%) in NSCLC tissue and was 5.58% (95%CI: 2%-9%) for the control group. Compared with normal lung tissue, RASSF1A methylation frequency in tumor tissue was significantly higher than that of the control group (OR=8.72, 95%CI: 4.88-15.58, P<0.05). Subgroup analysis showed that the RASSF1A gene promoter methylation rate of tumor tissue was higher than that of plasma group (OR=10.99, 95%CI: 2.48-48.68) and normal control tissue group (OR=8.74, 95%CI: 4.39-17.41).

CONCLUSIONS

The rate of RASSF1A promoter gene methylation in NSCLC patient tissue samples was higher than that of normal lung samples, whereas the rate of RASSF1A promoter gene methylation in the tissue has more significant effect on lung cancer occurrence. This finding indicates that RASSF1A gene promoter methylation could be used as an NSCLC biomarker and was involved in NSCLC carcinogenic effects.

Analysis of FHIT gene methylation in egyptian breast cancer women: association with clinicopathological features

BACKGROUND

Fragile histidine triad (FHIT) gene is a tumor suppressor gene which involved in breast cancer pathogenesis. Epigenetics alterations in FHIT contributes to tumorigenesis of breast cancer.

OBJECTIVE

Our objective was to study FHIT promoter region hypermethylation in Egyptian breast cancer patients and its association with clinicopathological features.

MATERIALS AND METHODS

Methylation-specific polymerase chain reaction was performed to study the hypermethylation of FHIT promoter region in 20 benign breast tissues and 30 breast cancer tissues.

RESULTS

The frequency of hypermethylation of FHIT promoter region was significantly increased in breast cancer patients compared to bengin breast disease patients. The Odd ?s ratio (95%CI) of development of breast cancer in individuals with FHIT promoter hypermethylation (MM) was 11.0 (1.22-250.8). There were also significant associations between FHIT promoter hypermethylation and estrogen, progesterone receptors negativity, tumor stage and nodal involvment in breast cancer pateints.

CONCLUSIONS

Our results support an association between FHIT promotor hypermethylation and development of breast cancer in Egyptian breast cancer patients. FHIT promoter hypermethylation is associated with some poor prognostic features of breast cancer.

Association of methylation of the RAR-β gene with cigarette smoking in non-small cell lung cancer with Southern-Central Chinese population

Pathogenesis of lung cancer is a complicated biological process including multiple genetic and epigenetic changes. Since cigarette smoking is confirmed as the most main risk factor of non-small cell lung cancer (NSCLC), the aim of this study was to determine whether tobacco exposure plays a role in gene methylation. Methylation of the RAR-β gene were detected using methylation-specific polymerase chain reaction in DNA from 167 newly diagnosed cases with NSCLC and corresponding 105 controls. A significant statistical association was found in the detection rate of the promoter methylation of RAR-β gene between NSCLC and controls (x2=166.01; p<0.01), and hypermethylation of the RAR-β gene was significantly associated with smoking status (p=0.038, p<0.05). No relationship was found between RAR-β gene methylation and pathologic staging including clinical stage, cell type, gender and drinking (p>0.05), and the methylation of RAR-β gene rate of NSCLC was slightly higher in stages III+IV (80.0%) than in I+II (70.8%). Similar results were obtained for methylation of the RAR-β gene between squamous cell carcinoma (77.9%) and other cell type lung cancer (73.9%). These results showed that the frequency of methylation increased gradually with the development of clinical stage in smoking-associated lung cancer patients, and tobacco smoke may be play a potential role in RAR-β gene methylation in the early pathogenesis and process in lung cancer, particularly squamous cell carcinoma. Aberrant promoter methylation is considered to be a promising marker of previous carcinogen exposure and cancer risk.

Association of RASSF1A promoter methylation with lung cancer risk: a meta-analysis

RASSF1A, regarded as a candidate tumor suppressor, is frequently silenced and inactivated by methylation of its promoter region in many human tumors. However, the association between RASSF1A promoter methylation and lung cancer risk remains unclear. To provide a more reliable estimate we conducted a meta-analysis of cohort studies to evaluate the potential role of RASSF1A promoter methylation in lung carcinogenesis. Relevant studies were identified by searches of PubMed, Web of Science, ProQest and Medline databasesusing the following key words: 'lung cancer or lung neoplasm or lung carcinoma', 'RASSF1A methylation' or 'RASSF1A hypermethylation'. According to the selection standard, 15 articles were identified and analysised by STATA 12.0 software. Combined odds ratio (OR) and 95% confidence interval (CI) were used to assess the strength of the association between RASSF1A promoter methylation and lung cancer risk. A chi-square-based Q test and sensitivity analyses were performed to test between-study heterogeneity and the contributions of single studies to the final results, respectively. Funnel plots were carried out to evaluate publication bias. Overall, a significant relationship between RASSF1A promoter methylation and lung cancer risk (OR, 16.12; 95%CI, 11.40-22.81; p<0.001) with no between-study heterogeneity. In subgroup analyses, increased risk of RASSF1A methylation in cases than controls was found for the NSCLC group (OR, 13.66, 95%CI, 9.529- 19.57) and in the SCLC group (OR, 314.85, 95%CI, 48.93-2026.2).

Expression and DNA methylation status of the Rap2B gene in human bronchial epithelial cells treated by cigarette smoke condensate

BACKGROUND

The relationship between lung cancer and smoking has been demonstrated. The Rap2B gene is usually overexpressed in lung cancers. This study was aimed to investigate the Rap2B gene expression and its promoter methylation in human bronchial epithelial cells (16HBE) treated by cigarette smoke condensate (CSC).

METHODS

16HBE cells were treated with CSC (1/8 IC50). Soft ager assay, tumorigenicity test, chromosome aberrations analysis were used to identify the transformed cells. The expression level of mRNA and protein of Rap2B was detected using real time PCR and Western blotting, respectively. The genome DNA methylation level was detected using combined bisulfite restriction analysis (COBRA) and the methylation status of the target fragment in Rap2B gene promoter was determined by bisulfite sequencing PCR (BSP).

RESULTS

The 16HBE cells were successfully malignant transformed after the chronic exposure to CSC. The expression of Rap2B gradually increased in the process of malignant transformation. Meanwhile, global DNA was hypomethylated. However, no obvious change was observed in the methylation level of Rap2B gene promoter in transformed 16HBE cells.

CONCLUSIONS

Rap2B gene may play an important role in the process of lung cancer and global DNA hypomethylation might be an early event in tumorigenesis.

Quantitative analysis of mRNA expression levels and DNA methylation profiles of three neighboring genes: FUS1, NPRL2/G21 and RASSF1A in non-small cell lung cancer patients

BACKGROUND

Tumor suppressor gene (TSG) inactivation plays a crucial role in carcinogenesis. FUS1, NPRL2/G21 and RASSF1A are TSGs from LUCA region at 3p21.3, a critical chromosomal region in lung cancer development. The aim of the study was to analyze and compare the expression levels of these 3 TSGs in NSCLC, as well as in macroscopically unchanged lung tissue surrounding the primary lesion, and to look for the possible epigenetic mechanism of TSG inactivation via gene promoter methylation.

METHODS

Expression levels of 3 TSGs and 2 DNA methyltransferases, DNMT1 and DNMT3B, were assessed using real-time PCR method (qPCR) in 59 primary non-small cell lung tumors and the matched macroscopically unchanged lung tissue samples. Promoter methylation status of TSGs was analyzed using methylation-specific PCRs (MSP method) and Methylation Index (MI) value was calculated for each gene.

RESULTS

The expression of all three TSGs were significantly different between NSCLC subtypes: RASSF1A and FUS1 expression levels were significantly lower in squamous cell carcinoma (SCC), and NPRL2/G21 in adenocarcinoma (AC). RASSF1A showed significantly lower expression in tumors vs macroscopically unchanged lung tissues. Methylation frequency was 38-76%, depending on the gene. The highest MI value was found for RASSF1A (52%) and the lowest for NPRL2/G21 (5%). The simultaneous decreased expression and methylation of at least one RASSF1A allele was observed in 71% tumor samples. Inverse correlation between gene expression and promoter methylation was found for FUS1 (rs = -0.41) in SCC subtype. Expression levels of DNMTs were significantly increased in 75-92% NSCLCs and were significantly higher in tumors than in normal lung tissue. However, no correlation between mRNA expression levels of DNMTs and DNA methylation status of the studied TSGs was found.

CONCLUSIONS

The results indicate the potential role of the studied TSGs in the differentiation of NSCLC histopathological subtypes. The significant differences in RASSF1A expression levels between NSCLC and macroscopically unchanged lung tissue highlight its possible diagnostic role in lung cancer in situ recognition. High percentage of lung tumor samples with simultaneous RASSF1A decreased expression and gene promoter methylation indicates its epigenetic silencing. However, DNMT overexpression doesn't seem to be a critical determinate of its promoter hypermethylation.