DNA hypermethylation of COL4A1 in ultraviolet-Binduced age-related cataract models in vitro and in vivo

AIM:To explore the DNA methylation of COL4A1 in ultraviolet-B(UVB)-induced age-related cataract(ARC)models in vitro and in vivo.METHODS:Human lens epithelium B3(HLEB3)cells and Sprague Dawley rats were exposure to UVB respectively.The MTT assay was utilized to evaluate cell proliferation.Flow cytometry was employed for analysis of cell apoptosis and cell cycle.COL4A1 expression in HLEB3 cells and anterior lens capsules were assessed using Western blot and reverse transcription-polymerase chain reaction(RTPCR).The localization of COL4A1 in HLEB3 cells was determined by immunofluorescence.The methylation status of CpG islands located in COL4A1 promoter was verified using bisulfite-sequencing PCR(BSP).DNMTs and TETs mRNA levels was examined by RT-PCR.RESULTS:UVB exposure decreased HLEB3 cells proliferation,while increased the apoptosis rate and cells were arrested in G0/G1 phase.COL4A1 expression was markedly inhibited in UVB treated cells compared to the controls.Hypermethylation status was detected in the CpG islands within COL4A1 promoter in HLEB3 cells subjected to UVB exposure.Expressions of DNMTs including DNMT1/2/3 were elevated in UVB treated HLEB3 cells compared to that in the controls,while expressions of TETs including TET1/2/3 showed the opposite trend.Results from the UVB treated rat model further confirmed the decreased expression of COL4A1,hypermethylation status of the CpG islands at promoter of COL4A1 and abnormal expression of DNMT1/2/3 and TET1/2/in UVB exposure group.CONCLUSION:DNA hypermethylation of COL4A1 promoter CpG islands is correlated with decreased COL4A1 expression in UVB induced HLEB3 cells and anterior lens capsules of rats.

p16 promoter hypermethylation:A useful serum marker for early detection of gastric cancer

AIM： TO determine p15 promoter hypermethylation in gastric tumoral tissue and serum samples, its impact on p16-protein expression, and correlation with clinical and histological features. METHODS： Samples were obtained from 52 histologically confirmed cases of gastric adenocarcinoma. Gastric tissue and serum of 50 age- and sex-matched individuals with normal gastroscopy and biopsy were obtained as control samples. Methylation-specific polymerase chain reaction （MSP） was used to evaluate methylation status of p16 promoter, p16-protein expression was analyzed by immunohistochemical staining on paraffin-embedded sections. RESULTS： Methylation was detected in 44.2% （23/52） of tumoral tissues. 60.9% of them were also methylated in serum, i.e., 26.9% of all patients （14/52）. Methylation was not detected in tissue and sera of control samples. p16-protein expression was decreased in 61.5% of cases （32/52）, and was significantly associated with promoter hypermethylation （P 〈 0.001）. Methylation was significantly more frequent in higher pathological grades （P 〈 0.05）. Methylation was not associated with other clinicopathological features and environmental factors including Hpylori infection and smoking. CONCLUSION： p16 promoter hypermethylation is an important event in gastric carcinogenesis. It is the principle mechanism of p16 gene silencing. It is related to malignant tumor behavior. Detection of DNA methylation in serum may be a biomarker for early detection of gastric cancer.

Promoter hypermethylation of CDH1, FHIT, MTAP and PLAGL1 in gastric adenocarcinoma in individuals from Northern Brazil

AIM：To evaluate the methylation status of CDH1, FHIT, MTAP and PLAGL1 promoters and the association of these findings with clinico-pathological characteristics.METHODS： Methylation-specific PCR （MSP） assay was performed in 13 nonneoplastic gastric adenocarcinorna, 30 intestinal-type gastric adenocarcinorna and 35 diffuse-type gastric adenocarcinorna samples from individuals in Northern Brazil. Statistical analyses were performed using the chi-square or Fisher＇s exact test to assess associations between rnethylation status and clinico-pathological characteristics.RESULTS： Hypermethylation frequencies of CDH1, FHIT, MTAPand PLAGL1 promoter were 98.7%, 53.9%, 23.1% and 29.5%, respectively. Hyperrnethylation of three or four genes revealed a significant association with diffuse-type gastric cancer compared with nonneoplastic cancer. A higher hyperrnethylation frequency was significantly associated with H pylori infection in gastric cancers, especially with diffuse-type. Cancer samples without lymph node metastasis showed a higher FHIT hypermethylation frequency. MTAP hypermethylation was associated with H pylori in gastric cancer samples, as well as with diffuse-type compared with intestinal-type. In diffuse-type, MTAP hypermethylation was associated with female gender.CONCLUSION： Our findings show differential gene methylation in tumoral tissue, which allows us to conclude that hypermethylation is associated with gastric carcinogenesis. MTAP promoter hypermethylation can be characterized as a marker of diffuse-type gastric cancer, especially in women and may help in diagnosis, prognosis and therapies. The H pylori infectious agent was present in 44.9% of the samples. This infection may be correlated with the carcinogenic process through the gene promoter hypermethylation, especially the MTAP promoter in diffuse-type. A higher H pylori infection in diffuse-type may be due to greater genetic predisposition.

P16 gene hypermethylation and hepatocellular carcinoma:A systematic review and meta-analysis

AIM:To quantitatively investigate the effect of p16 hypermethylation on hepatocellular carcinoma (HCC) and hepatocirrhosis using a meta-analysis of available casecontrol studies.METHODS:Previous studies have primarily evaluated the incidence of p16 hypermethylation in HCC and corresponding control groups,and compared the incidence of p16 hypermethylation in tumor tissues,pericancer liver tissues,normal liver tissues and non-tumor liver tissues with that in other diseases.Data regarding publication information,study characteristics,and incidence of p16 hypermethylation in both groups were collected from these studies and summarized.RESULTS:Fifteen studies,including 744 cases of HCC and 645 non-tumor cases,were identified for meta-analysis.Statistically significant odds ratios (ORs) of p16 hypermethylation were obtained from tumor tissues and non-tumorous liver tissues of HCC patients (OR 7.04,95% CI:3.87%-12.78%,P < 0.0001),tumor tissues of HCC patients and healthy liver tissues of patients with other diseases (OR 12.17,95% CI:6.64%-22.31%,P < 0.0001),tumor tissues of HCC patients and liver tissues of patients with non-tumorous liver diseases (OR 6.82,95% CI:4.31%-10.79%,P < 0.0001),and cirrhotic liver tissues and non-cirrhotic liver tissues (OR 4.96,95% CI:1.45%-16.96%,P=0.01).The pooled analysis showed significantly increased ORs of p16 hypermethylation (OR 6.98,95% CI:4.64%-10.49%,P < 0.001) from HCC tissues and cirrhotic tissues.CONCLUSION:P16 hypermethylation induces the inactivation of p16 gene,plays an important role in hepatocarcinogenesis,and is associated with an increased risk of HCC and liver cirrhosis.

Underexpression of LATS1 TSG in colorectal cancer is associated with promoter hypermethylation

AIM:To investigate large tumor suppressor 1 (LATS1 ) expression, promoter hypermethylation, and microsatellite instability in colorectal cancer (CRC).METHODS:RNA was isolated from tumor tissue of 142 CRC patients and 40 colon mucosal biopsies of healthy controls. After reverse transcription, quantitative polymerase chain reaction (PCR) was performed, and LATS1 expression was normalized to expression of the ACTB and RPL32 housekeeping genes. To analyze hypermethylation, genomic DNA was isolated from 44 tumor CRC biopsies, and methylation-specific PCR was performed. Microsatellite instability (MSI) status was checked with PCR using BAT26, BAT25, and BAT40 markers in the genomic DNA of 84 CRC patients, followed by denaturing gel electrophoresis. RESULTS:Decreased LATS1 expression was found in 127/142 (89.4%) CRC cases with the average ratio of the LATS1 level 10.33 ± 32.64 in CRC patients vs 32.85 ± 33.56 in healthy controls. The lowest expression was found in Dukes' B stage tumors and G1 (welldifferentiated) cells. Hypermethylation of the LATS1 promoter was present in 25/44 (57%) CRC cases analyzed. LATS1 promoter hypermethylation was strongly associated with decreased gene expression; methylated cases showed 162× lower expression of LATS1 than unmethylated cases. Although high-grade MSI (mutation in all three markers) was found in 14/84 (17%) cases and low-grade MSI (mutation in 1-2 markers) was found in 30/84 (36%) cases, we found no association with LATS1 expression. CONCLUSION:Decreased expression of LATS1 in CRC was associated with promoter hypermethylation, but not MSI status. Such reduced expression may promote progression of CRC.

Hypermethylation and aberrant expression of Wnt antagonist secreted frizzled-related protein 1 in gastric cancer

AIM： To identify the methylation of secreted frizzled-related protein 1 （SFRP1） in gastric cancer and to investigate the aberrant expression of SFRP1 and its correlation with the clinical pathological features of patients. METHODS： We determined SFRP1 methylation and SFRP1 mRNA expression in 3 gastric cancer cell lines SGC-7901, BGC-823, HGC-27, from 52 primary gastric cancer specimens and matched tumor adjacent tissue specimens by methylation-specific （MSP） PCR and RT-PCR respectively. Fisher＇s exact test was used to analyze the statistical association between clinical pathological data and aberrant expression of SFRP1. RESULTS： In 3 cancer cell lines, BGC-823 and HGC-27 had methylated SFRP1 and lost SFRP1 mRNA expression. After treatment of BGC-823 and HGC-27 with the demethylating agent, 5-aza-2′-deoxycytidine, SFRP1 was re-expressed. In 52 primary gastric cancer specimens and matched tumor adjacent tissue specimens, hypermethylation of SFRP1 was detected in 23 （44%） and 8 （15%） specimens respectively （x^2= 10.34, P 〈 0.01）. Loss of SFRP1 expression was detected in 17（33%） and 6 （12%） specimens respectively （x^2= 6.75, P 〈 0.01）. There was a significant correlation between SFRP1 hypermethylation and SFRP1 expression loss. SFRP1 expression was also correlated significantly with tumor stage and lymph node status, but not with patient sex, age and histological type. CONCLUSION： SFRP1 inactivation is a common and early event caused mainly by hypermethylation in gastric cancer. SFRP1 expression loss may be correlated with tumor metastasis in primary gastric cancer.

Expression and hypermethylation of p27^(kip1) in hepatocarcinogenesis

AIM： To study the expressions of p27^kip1 protein and p27mRNA, the hypermethylation of p27^kip1 and the relation between them in various stages of hepatocarcinogenesis. METHODS： p27 protein and p27mRNA were detected by immunohistochemical staining and in situ hybridization respectively in 68 cases of normal liver, liver cirrhosis, pericancerous cirrhosis and hepatocellular carcinoma （HCC）. The hypermethylation of p27^kip1 was detected by methylation-specific PCR （MSP） in 44 cases of normal liver, liver cirrhosis, and HCC. RESULTS： The positive rate of p27 protein was 66.7% （4/6） in normal liver, 60.0% （6/10） in liver cirrhosis, 50.0% （12/24） in pericancerous cirrhosis and 21.4% （6/28） in HCC. There were no statistical differences in normal liver, liver cirrhosis and pericancerous cirrhosis, but the positive rate of p27 protein significantly decreased in HCC compared to that in the other groups （P = 0.006, %2 = 7.664）. The positive rate of p27^kip1 mRNA was 83.3% （5/6） in normal liver, 70.0% （7/10） in liver cirrhosis, 75.0% （18/24） in pericancerous cirrhosis and 25.0% （7/28） in HCC. There were no statistical differences in normal liver, liver cirrhosis and pericancerous cirrhosis, but the positive rate of p27^kip1 mRNA also significantly decreased in HCC compared to that in the other groups （P = 0.000, %2 = 16.600）. In addition, there was a significant correlation between the expression of p27 protein and p27mRNA in the integrated group of normal liver and liver cirrhosis. However, no significant correlation was found between pericancerous cirrhosis and HCC. Using MSP, we found that 1 HCC in 44 cases （including 6 cases of normal liver, 10 cases of liver cirrhosis and 28 cases of HCC） was methylated, whose p27 protein and p27mRNA were negative. CONCLUSION： The reduction or loss of p27 protein and p27mRNA are potentially involved in hepatocarcinogenesis. The hypermethylation of p27 might lead to the loss of p27mRNA transcription.

Hypermethylation and aberrant expression of secreted fizzled-related protein genes in pancreatic cancer

AIM：To determine the methylation status and aberrant expression of some secreted frizzled-related protein（SFRP） genes in pancreatic cancer and explore their role in pancreatic carcinogenesis.METHODS：Methylation status and expression of SFRP genes were detected by methylation-specific PCR（MSPCR） and reverse-transcription PCR（RT-PCR） respectively.RESULTS：The frequencies of methylation for SFRP genes 1,2,4,5 were 70%,48.3%,60% and 76.7% in pancreatic cancer samples,and 21.7%,20%,10% and 36.7% in matched cancer adjacent normal tissue samples,respectively（χ^2 = 28.23,P 〈 0.0001 for SFRP gene 1;χ^2 = 10.71,P = 0.001 for SFRP gene 2;χ^2 = 32.97,P 〈 0.0001 for SFRP gene 4;χ^2 = 19.55,P 〈 0.0001 for SFRP gene 5）.Expression loss of SFRP genes 1,2,4 and 5 was found in 65%,40%,55% and 71.7% of 60 pancreatic cancer samples,and 25%,15%,18.3% and 31.7% of matched cancer adjacent normal tissue samples,respectively（χ^2 = 19.39,P 〈 0.0001 for SFRP gene 1;χ^2 = 9.40,P = 0.002 for SFRP gene 2;χ^2 = 17.37,P 〈 0.0001 for SFRP gene 4;χ^2 = 19.22,P 〈 0.0001 for SFRP gene 5）.SFRP gene 1 was methylated but not expressed in PC-3 and PANC-1,SFRP gene 2 was methylated but not expressed in PANC-1 and CFPAC-1,SFRP gene 4 was methylated but not expressed in PC-3,and SFRP gene 5was methylated but not expressed in CFPAC-1.CONCLUSION： Hypermethylation and aberrant expression of SFRP genes are common in pancreatic cancer, which may be involved in pancreatic carcinogenesis.

Helicobacter pylori infection in relation to E-cadherin gene promoter polymorphism and hypermethylation in sporadic gastric carcinomas

AIM: To study Helicobacter pylori (H pylori) infection in relation to E-cadherin (E-cad) promoter polymorphism and hypermethylation in GCs.METHODS: Specimens were taken from representative cancerous lesions and adjacent non-cancerous epithelia of 67 resected GCs. Hpyloriwas detected by real-time PCR of the cagA gene from non-neoplastic epithelium.E-cad promoter polymorphism and hypermethylation were determined by restriction fragment length polymorphism analysis and methylation-specific PCR, respectively. Expression of E-cad protein was determined by immunohistochemistry.RESULTS: Hpyloriwas found in 57% of patients with GC.H pylori infection was more frequently found in tumors with the -160C/C genotype than those with the -160C/A and -160A/A genotypes (74% vs47%, P = 0.02). Hpylori infection was associated with E-cad methylation in nonneoplastic epithelium; however, no significant difference in H pylori was observed between methylated and unmethylated cancerous lesions.CONCLUSION: Patients with the -160C/C genotype might require Hpyloriinfection to promote the inactivation of CDH1, suggesting that Hpylori infection might affect GC in an initial stage because polymorphism is germ line.Mechanism of hypermethylation of CDH1 promoter in GC is complex, and Hpyloriinfection might affect it in an initial stage.

The role of aberrant promoter hypermethylation of DACT1 in bladder urothelial carcinoma

The purpose of this study was to determine the relationship between hypermethylation of DACT1 gene pro-moter and lower mRNA expression in bladder urothelial carcinoma tissue.The methylation status of 29 urothelial carcinoma samples and 29 normal tissue samples were examined by methylation-specific polymerase chain reac-tion（MSP）.The DACT1 mRNA transcript levels and DACT1 protein levels in all samples were then evaluated to define the relationship between the methylation status of the DACT1 promoter and its expression at the transcrip-tional and translational levels.Decreased expression of DACT1 was detected in 89.66% of urothelial carcinomas（26/29;P 〈 0.005）.Promoter hypermethylation was found in 58.62%（17/29） urothelial carcinomas and 25%（7/29） normal tissues,respectively（P 〈 0.05）.DACT1 expression was lower in tissues where the DACT1 gene promoter was hypermethylated than in unmethylated tissues（0.25±0.17 vs 0.69±0.30,P 〈 0.05）.DACT1 gene hyper-methylation was closely related to tumor size,grade and stage（P 〈 0.05）.Our results indicate that silencing and downregulation of DACT1 mRNA may be implicated in carcinogenesis and the progression of bladder urothelial carcinoma,and may be a potential prognostic factor.

HYPERMETHYLATION STATUS OF E-CADHERIN AND p16^(INK4a) IN GASTROINTESTINAL STROMAL TUMOR

Objective： To investigate the methylation status of CpG island in E-cadherin（CDHl）, P16^INK4a（ P16）promoter region ,and to analyze their role in gastrointestinal stromal rumor （GISTs）. Methods： A total of 56 surgically resected GISTs were obtained from January 2003 to December 2005. The routine H＆E-stained sections and CD117, CD34-immunoreactions were reviewed to verify the morphologic diagnosis. Methylation status of the CDH1, P16^INK4a promoter region was analyzed by methylation specific polymerase chain reaction （MSP） from chemically modified DNA after Na-bisulfite treatment. Results： The frequency of CDHlgene methylation was 32% （18 of 56） in GISTs. The rate was 9% （1 of 11）, 21% （4 of 19）, 41.6% （5 of 12）, and 57% （8 of 14） for very low risk, low risk, intermediate risk, and high risk GISTs; P16^INK4a methylation was found in 19 of 56（34%） cases. The rate was 0% （0 of 11）, 16% （3 of 19）, 50% （6 of 12）, and 71% （10 of 14） for very low risk, low risk, intermediate risk, and high risk GISTs. Statistical analysis indicated that of the 56 cases, there was significant association of CDH^INK4a and/or P16^INK4a methylation status with tumor malignant behavior （methylation rate 23/56, 41%, P〈0.01） and site （P〈0.05）. Conclusion： E-cadherin （CDHI） and/or P16^INK4a promoter hypermethylation is strongly associated with risk grade, may be a useful biomarker for GISTs risk assessment, and may shed light on new therapeutic options to treat GISTs

Promoter hypermethylation and loss of CD133 gene expression in colorectal cancers

AIM: To understand CD133 promoter hypermethyl-ation and expression in 32 colorectal cancer cell lines. METHODS: Nucleic acid was isolated from 32 colorectal cancer cell lines and CD133 expression levels were measured by reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR. Promoter methylation status of the CD133 gene was analyzed with a methylation-specific PCR after sodium-bisulfi te modification and by clonal sequencing analysis. The correlation between expression and promoter methylation of CD133 gene was confirmed with treatment of 5-aza-2’-deoxycytidine. RESULTS: We measured CD133 expression levels in 32 colorectal cancer cell lines. RT-PCR analysis showed undetectable or low levels of CD133 expression in 34.4%of cell lines. To verify the relation between CD133 expression and methylation status of the CD133 gene promoter in colorectal carcinogenesis, CD133 gene promoter hypermethylation was analyzed in 32 cancer cell lines. Promoter hypermethylation was detected in 13 (40.6%) of the cell lines using methylation specificPCR and confirmed by bisulfite sequencing analysis. Treatment of 11 of the cell lines with the demethylation agent 5-aza-2’-deoxycytidine recovered CD133 expression in most of them. CONCLUSION: Transcriptional repression of CD133 is caused by promoter hypermethylation of the CD133 CpG islands in some of colorectal cancer cell lines. The study may contribute to the understanding of the role of CD133 inactivation in the progression of colorectal cancers.

Analysis of Inactivation of hMLH1 by Promoter Hypermethylation and Microsatellite Instability in Gastric Carcinogenesis

OBJECTIVE To study the microsatellite instability (MSI) and methylation state of the hMLH1 gene promoter and their mechanisms underlying the development of gastric cancer. METHODS Forty-one gastric cancer samples were obtained from patients undergoing surgery and 46 chronic atrophic gastritis tissues with dysplasia or intestinal metaplasia (IM) were obtained from patients undergoing gastro-endoscopy. Fourteen normal gastric mucosal samples were used as controls. Genomic DNA was extracted from the samples and 5 microsatellite markers were used to measure MSI. Methylation-specific PCR (MSP) was used to screen the methylation state of the samples. DNA sequencing and immunohistochemistry were performed to verify the results. RESULTS MSI was identified in 22 out of the 41 (53.7%) gastric cancers, of which 8 cases showed high-level MSI (2 or more loci altered) and 14 showed low-level MSI (1 locus altered). MSI was also detected in 12 out of 46 (26.1%) pre-cancerous lesions of the stomach, whereas it was not seen in the normal tissue. Moreover, hMLH1 hypermethylation was detected in 17 out of the 41 (41.5%) gastric cancers, 9 out of the 46 (19.6%) pre-cancerous lesions and 0 out of the 14 normal tissue. Significant differences in frequency of MSI and hMLH1 promoter methylation were observed among gastric cancers, precancerous lesions and normal gastric tissue. Gastric samples with MSI had a tendency to be hypermethylated in the hMLH1 promoter. DNA sequencing and immunohistochemistry results also confirmed that hMLH1 promoter methylation could lead to loss of the hMLH1 protein and gene silence which sequentely resulted in gene mismatch and MSI. CONCLUSION Accumulation of MSI and hMLH1 promoter methylation may be important early molecular events during gastric carcinogenesis and may contribute to the acquisition of a transformed cell phenotype and the development of gastric cancer.

Hypermethylation of tumor suppressor and tumor-related genes in neoplastic and non-neoplastic gastric epithelia

A number of tumor suppressor and tumor-related genes exhibit promoter hypermethylation with resultant gene silencing in human cancers.The frequencies of methylation differ among genes and genomic regions within CpG islands in different tissue types.Hypermethylation initially occurs at the edge of CpG islands and spreads to the transcription start site before ultimately shutting down gene expression.When the degree of methylation was quantitatively evaluated in neoplastic and non-neoplastic gastric epithelia using DNA microarray analysis,highlevel methylation around the transcription start site appeared to be a tumor-specific phenomenon,although multiple tumor suppressor genes became increasingly methylated with patient age in non-neoplastic gastric epithelia.Quantitative analysis of DNA methylation is a promising method for both cancer diagnosis and risk assessment.

Promoter Hypermethylation of DNA Repair Gene MGMT in Laryngeal Squamous Cell Carcinoma

The relationship between hypermethylation of CpG islands in the promoter regions of O^6- methylguanine DNA methyhransferase （MGMT） genes and laryngeal squamous cell carcinoma was explored. Methylation-specific PCR and semi-quantitative RT-PCR were used to study the promoter methylation and mRNA expression of the MGMT gene in laryngeal carcinoma tissues, tissues adjacent to the tumor and normal laryngeal tissues. Hypermethylation of MGMT gene was detected in 16 samples of 46 （34.8 %） laryngeal squamous cell carcinoma samples. However, the MGMT hypermethylation was not detected in all tissues adjacent to the tumors and normal tissues. No significant difference in MGMT gene hypermethylation was found in samples with different histological grades （χ^2= 3. 130, P=0. 077） or in samples from patients with different TNM status （χ^2= 3. 957, P=0. 138）. No expression of MGMT mRNA was detected in all hypermethylated laryngeal carcinoma tissues. The expression of MGMT mRNA was detected in all unmethylated laryngeal carcinoma tissues, tissues adjacent to the tumors and normal tissues. It suggests that MGMT gene promoter hypermethylation is associated with MGMT gene transcription loss in laryngeal carcinoma tissues and possibly plays an important role in carcinogenesis of laryngeal tissues.

The role of XPC protein deficiency in tobacco smoke-induced DNA hypermethylation of tumor suppressor genes

DNA hypermethylation of tumor suppressor genes has been frequently observed in cancer patients, and therefore, may provide a valuable biomarker for cancer prevention and treatment. DNA hypermethylation may also provide an important mechanism in cancer progression. Lung cancer is strongly associated with exposure to environmental carcinogens, especially tobacco smoke. DNA damage generated by tobacco smoke is believed to play an important role in lung cancer development. XPC is a DNA damage recognition protein required for DNA repair and other DNA damage responses and attenuated XPC protein levels have been detected in many lung cancer patients. We studied the role of XPC protein deficiency in tobacco smoke-caused DNA hypermethylation of important tumor suppressor genes. Using both normal human fibroblasts (NF) and XPC-deficient hu man fibroblasts (XPC), our DNA methylation studies demonstrated that the XPC deficiency caused elevated levels of DNA hypermethylation in both Brca1 and Mlh1 tumor suppressor genes following exposure to tobacco smoke condensate (TSC). The results of our ChIP studies revealed that the XPC deficiency led to an increased binding of DNA methyltransferase 3A (DNMT3A) at the promoter region CpG island-containing sequences of these genes under the TSC treatment;however, this increase was partially diminished with prior treatment with caffeine. The results of our immuno-precipitation (IP) studies demonstrated a protein-protein interaction of the ATR with DNMT3A. Our western blots revealed that the XPC deficiency caused an increase in TSC-induced ATR phosphorylation at serine 428, an indicator of ATR activation. All these results suggest that XPC deficiency causes an accelerated DNA hypermethylation in important tumor suppressor genes under tobacco smoke exposure and activation of the ATR signaling pathway is involved in this DNA hypermethylation process.

Epigenetic Aberrant Hypermethylation of DNA in Endometrial Cancer: Application as a Biomarker

Endometrial cancer is the seventh most common cancer worldwide among females and accounts for about 40% of cancers of the uterus in Japan. An increase in incidence and a reduction in onset age of this disease are also likely, which makes it important to define the pathogenesis and develop effective treatment. However, the mechanism of canceration in the endometrium is unclear and development of endometrial cancer cannot be explained only by mutations of cancer-related genes. In contrast, epigenetic analyses have shown the importance of aberrant DNA hypermethylation in the canceration mechanism. In development of type 1 endometrial cancer, breakdown of the DNA mismatch repair system plays a large role, with changes in the human mutL homologue 1 (hMLH1) gene being of most importance. Studies to detect aberrant DNA hypermethylation of cancer cells present in microscopic amounts in vivo and to apply these data to diagnosis of cancer have been started. Epigenetic changes have also been examined as a marker of sensitivity to anticancer drugs. Aberrant hypermethylation of checkpoint with forkhead-associated and ring finger (CHFR), a mitotic phase checkpoint gene, is correlated with sensitivity to treatment with microtubule inhibitors and may be a marker for the response of endometrial cancer to anticancer drugs. Epigenetic aberrant DNA methylation of other genes may also be useful as clinical biomarkers for diagnosis and treatment of endometrial cancer.

RASSFIA Promoter Hypermethylation as a Prognosis and Diagnosis for Breast Cancer in Vietnamese Population

Aberrant tumor suppressor gene promoter methylation was associated with the several cancers, including breast cancer, which was the common female deaths in most countries involved in Vietnam. The methylation in tumor suppressor genes, including RASSFIA, were the key targets of establishing the potential biomarkers for prognosis and early diagnosis of breast cancer. In present study, with the aim towards using the hypermethylation at CpG islands of promoter of RASSFIA as the biomarker for breast cancer in Vietnamese population, MSP （methyl specific PCR） was carried out to analyze the hypermethylation status ofRASSFIA gene in 115 samples including 95 breast cancer specimens and 20 normal breast tissues from another disease （not breast cancer）. All samples were obtained from Ho Chi Minh City Medical Hospital, Vietnam. The known predictive and prognostic factors： HER2/neu overexpression was immunohistochemistry stained as input value for breast cancer specimens. For input value confirmed, the overexpression of p53 protein was also analyzed together with prior immunochemical assay. The results indicated that the hypermethylation of frequencies for methylation of given gene reached 42.1% （P 〈 0.05）. In addition, the DNA hypermethylation of RASSFIA gene increased the possibility to be breast cancer with high incidence via calculated of odd ratio （P 〈 0.05）. In conclusion, the hypermethylation of candidate genes could be used as the promising biomarkers applying in Vietnamese breast cancer patients.

No Association between p53 Immunohistochemical Staining and RASSF1 or DAPK1 Hypermethylation in Non-Small Cell Lung Cancer

p53 mutations have been linked with shortened survival rates in non-small cell lung cancer (NSCLC). Hypermethylation of RASSF1 and DAPK1 genes, which are downstream targets of p53, has also been linked to a poor prognosis in lung cancer patients. We investigated whether p53 mutations, assessed as p53 stabilization by immunohistochemistry (IHC), were independent of DAPK1 and RASSF1 promoter hypermethylation. We examined 103 resected NSCLC tumors for which we had p53 IHC and RASSF1 and DAPK1 methylation data. p53 protein expression was determined by IHC and graded using a semi-quantitative scoring method. DAPK1 and RASSF1 methylations were determined on tumor blocks by MethyLight real-time PCR assays represented as the percent of methylated reference DNA (PMR). Our primary results found no evidence for an association between the p53 IHC score and RASSF1 and DAPK1 PMR values, P = 0.46 and P = 0.68, respectively.

Promoter hypermethylation of tissue specific tumor supressor genes and point mutation in K-ras, c-myc proto-oncogenes in urinary (transitional cell) bladder carcinoma

In a total of 83 UN specimens were investigated for proto-oncogene mutations, tumor supressor genes promoter methylation status and c-myc and Ki-67 expression. Point mutations in c-myc were detected in cases with high grade and proliferation index. Mutated K-ras proto-onco- gene profiles were detected in 17 (21%) tumoral spiecemens that examined. Tumor specimens were also showed hypermethylated promoter domain for the SFRP2, MGMT tumor supressor genes. These findings showed the combine effect of mutated c-myc and K-ras oncogene and epigenetic inactivation of tissue specific tumor supressor genes (TS) play a crucial role in tumor progression and recurrence in UN carcinogenesis.