• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7091-7095
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• 2014

Background: The study aimed to evaluate the incidence of CpG island promoter methylation of BMP6, a member of the transforming growth factor beta family, in tissue samples from colorectal cancers (CRC) and look for its association with BMP6 expression and clinicopathological correlation. Materials and Methods: Methylation specific PCR for the BMP6 promoter region was performed with 85 frozen tissue samples of CRC and 45 of normal colon. Methylation status of MLH1 was also determined by the same method. Expression of BMP6 was evaluated by immunohistochemistry (IHC), using Allred's scoring system. The methylation status was analyzed against clinical and pathological parameters in CRC. Results: The study revealed BMP6 hypermethylation in 34 of 85 tumor specimens (40%), and 15 out of 45 normal tissue samples from CRC (33%). The incidence of hypermethylation was inversely correlated with IHC score. Allred's scores of 7 or more were correlated with lower frequency of BMP6 hypermethylation (29% compared to 50% in the remaining, p-value 0.049). However, there was no association between hypermethylation status and any clinicopathological parameters. The methylation status of BMP6 was not correlated with that of MLH1, a key methylation determinant in CRC. On survival analysis, there was no significant difference in progress-free survival (PFS) between the cases with and without hypermethylation (2-year PFS 74% and 76%, respectively). Conclusions: CpG island methylation of BMP6 is found in high frequency in CRC and this epigenetic event is associated with suppressed protein expression in the tumor tissue. However, the marker is not associated with tumor progression of the disease.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.4
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• pp.1615-1619
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• 2015

Background: Promoter hypermethylation mediated gene silencing of tumor suppressor genes is considered as most frequent mechanism than genetic aberrations such as mutations in the development of cancers. BRD7 is a single bromodomain containing protein that functions as a subunit of SWI/SNF chromatin-remodeling complex to regulate transcription. It also interacts with the well know tumor suppressor protein p53 to trans-activate genes involved in cell cycle arrest. Loss of expression of BRD7 has been observed in breast cancers and nasopharyngeal carcinomas due to promoter hypermethylation. However, the genetic status of BRD7 in oral squamous cell carcinomas (OSCCs) is not known, although OSCC is one of the most common among all reported cancers in the Indian population. Hence, in the present study we investigated OSCC samples to determine the occurrence of hypermethylation in the promoter region of BRD7 and understand its prevalence. Materials and Methods: Genomic DNA extracted from biopsy tissues of twenty three oral squamous cell carcinomas were digested with methylation sensitive HpaII type2 restriction enzyme that recognizes and cuts unmethylated CCGG motifs. The digested DNA samples were amplified with primers flanking the CCGG motifs in promoter region of BRD7 gene. The PCR amplified products were analyzed by agarose gel electrophoresis along with undigested amplification control. Results: Methylation sensitive enzyme technique identified methylation of BRD7 promoter region seventeen out of twenty three (74%) well differentiated oral squamous cell carcinoma samples. Conclusions: The identification of BRD7 promoter hypermethylation in 74% of well differentiated oral squamous cell carcinomas indicates that the methylation dependent silencing of BRD7 gene is a frequent event in carcinogenesis. To the best of our knowledge, the present study is the first to report the occurrence of BRD7and its high prevalence in oral squamous cell carcinomas.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.6
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• pp.2219-2225
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• 2015

SHP1 negatively regulates the Janus kinase 2/signal transducer and activator of transcription (JAK2/STAT) signaling pathway, which is constitutively activated in myeloproliferative neoplasms (MPNs) and leukemia. Promoter hypermethylation resulting in epigenetic inactivation of SHP1 has been reported in myelomas, leukemias and other cancers. However, whether SHP1 hypermethylation occurs in MPNs, especially in Chinese patients, has remained unclear. Here, we report that aberrant hypermethylation of SHP1 was observed in several leukemic cell lines and bone marrow mononuclear cells from MPN patients. About 51 of 118 (43.2%) MPN patients including 23 of 50 (46%) polycythaemia vera patients, 20 of 50 (40%) essential thrombocythaemia and 8 of 18 (44.4%) idiopathic myelofibrosis showed hypermethylation by methylation-specific polymerase chain reaction. However, SHP1 methylation was not measured in 20 healthy volunteers. Hypermethylation of SHP1 was found in MPN patients with both positive (34/81, 42%) and negative (17/37, 45.9%) JAK2V617F mutation. The levels of SHP1 mRNA were significantly lower in hypermethylated samples than unmethylated samples, suggesting SHP1 may be epigenetically inactivated in MPN patients. Furthermore, treatment with 5-aza-2'-deoxycytidine (AZA) in K562 cells showing hypermethylation of SHP1 led to progressive demethylation of SHP1, with consequently increased reexpression of SHP1. Meanwhile, phosphorylated JAK2 and STAT3 were progressively reduced. Finally, AZA increased the expression of SHP1 in primary MPN cells with hypermethylation of SHP1. Therefore, our data suggest that epigenetic inactivation of SHP1 contributes to the constitutive activation of JAK2/STAT signaling. Restoration of SHP1 expression by AZA may contribute to clinical treatment for MPN patients.

• The Journal of the Korean bone and joint tumor society
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• v.15 no.1
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• pp.13-25
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• 2009

Purpose: The DNA repair protein, $O^6$-methylguanine-DNA methyltransferase (MGMT), removes alkyl adducts from the $O^6$ position of guanine. Epigenetic inactivation of MGMT has been found in human neoplasia and considered one of the implicated factors in chemoresistance. Materials and Methods: Sixty-two patiensts with soft tissue sarcomas (STS) were analyzed for the status of MGMT protein expression by immunohistochemistry and the promoter hypermethylation of the MGMT gene using methylation-specific PCR. Result: The loss of MGMT expression was found in 20 cases (32.3%) of total 62 STS. MGMT promoter hypermethylation rate was 25.0% (11/44 cases). The loss of MGMT expression showed significant association with high AJCC stage, high FNCLCC grade, and aggressive behavior. However,when the group who received chemotherapy was analyzed (n=27), loss of MGMT expression was correlated with worse survival in multivariate analysis (p=0.024). MGMT promoter hypermethylation is associated with high FNCLCC grade. MGMT promoter hypermethylation status had a strong correlation with loss of MGMT expression (p=0.000). Conclusion: Our results suggest that MGMT promoter hypermethylation and loss of MGMT expression had a tendency to be associated with poor prognosis and that loss of MGMT protein expression is frequently occurs via MGMT promoter hypermethylation.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.20
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• pp.8957-8961
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• 2014

Background: Promoter hypermethylation leads to altered gene functions and may result in malignant cellular transformation. Thus, identification of biomarkers for hypermethylated genes could be useful for diagnosis, prognosis, and therapeutic treatment of oral squamous cell carcinoma (OSCC). Objectives: To screen hypermethylated genes with a microarray approach and to validate selected hypermethylated genes with the methylation-specific polymerase chain reaction (MSPCR). Materials and Methods: Genome-wide analysis of normal oral mucosa and OSCC tissues was conducted using the Illumina methylation microarray. The specified differential genes were selected and hypermethylation status was further verified with an independent cohort sample of OSCC samples. Candidate genes were screened using microarray assay and run by MSPCR analysis. Results: TP73, PIK3R5, and CELSR3 demonstrated high percentages of differential hypermethylation status. Conclusions: Our microarray screening and MSPCR approaches revealed that the signature candidates of differentially hypermethylated genes may possibly become potential biomarkers which would be useful for diagnostic, prognostic and therapeutic targets of OSCC in the near future.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.4177-4181
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• 2012

Cancer is a multi-factorial disease and variation in genetic susceptibility, due to inherited differences in the capacity to repair mismatches in the genome, is an important factor in the development of gastric cancer (GC), for example. Epigenetic changes, including aberrant methylation of 5/CpG islands in the promoter regions of mismatch repair (MMR) genes like hMLH1, have been implicated in the development of various types of GC. In the present study we evaluated the role of hMLH1 promoter hypermethylation in Kashmiri GC patients and controls, and assessed correlations with various dietary and lifestyle factors. The study included 70 GC patients (56 males and 14 females; age ($mean{\pm}S.D$) $50{\pm}11.4$ years). Distinction between methylated and unmethylated was achieved with MS-PCR and DNA band patterns. The Chi-square test was applied to assess the risk due to promoter hypermethylation. We found a strikingly high frequency of promoter hypermethylation in GC cases than in normal samples (72.9% (51/70) in GC cases vs 20% (14/70) in normal samples (p=0.0001).We also observed a statistically significant association between methylated hMLH1 gene promoter and smoking, consumption of sundried vegetables and hot salted tea with the risk of GC. This study revealed that hMLH1 hypermethylation is strongly associated with GC and suggested roles for epigenetic changes in stomach cancer causation in the Kashmir valley.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.219-223
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• 2016

Background: Promoter hypermethylation is a frequent epigenetic mechanism for gene transcription repression in cancer and is one of the hallmarks of the disease. Cadherin EGF LAG seven-pass G-type receptor 3 (CELSR3) contributes to cell contact-mediated communication. Dysregulation of promoter methylation has been reported in various cancers. Objectives: The objectives of this study were to investigate the CELSR3 hypermethylation level in oral squamous cell carcinomas (OSCCs) using methylation-sensitive high-resolution melting analysis (MS-HRM) and to correlate CELSR3 methylation with patient demographic and clinicopathological parameters. Materials and Methods: Frozen tissue samples of healthy subjects' normal mucosa and OSCCs were examined with regard to their methylation levels of the CELSR3 gene using MS-HRM. Results: MS-HRM analysis revealed a high methylation level of CELSR3 in 86% of OSCC cases. Significant correlations were found between CELSR3 quantitative methylation levels with patient ethnicity (P=0.005), age (P=0.024) and pathological stages (P=0.004). A moderate positive correlation between CELSR3 and patient age was also evident (R=0.444, P=0.001). Conclusions: CELSR3 promoter hypermethylation may be an important mechanism involved in oral carcinogenesis. It may thus be used as a biomarker in OSCC prognostication.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3139-3142
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• 2013

Associations of P16, MGMT, hMLH1 and hMLH2 with gastric cancer and their relation with MTHFR status in gastric patients who were confirmed with pathological diagnosis were assessed. Aberrant DNA methylation of P16, MGMT, hMLH1 and hMLH2 and polymorphisms of MTHFR C677T were assayed. The proportional DNA hypermethylation in P16, MGMT, hMLH1 and hMLH2 in cancer tissues was significantly higher than in remote normal-appearing tissues. DNA hypermethylation of P16 and MGMT was correlated with the T and N stages. Individuals with homozygotes (TT) of MTHFR C677T had significant risk of hypermethylation of MGMT in cancer tissues [OR (95% CI)= 3.47(1.41-7.93)]. However, we did not find association between polymorphism in MTHFR C677T and risk of hypermethylation in P16, MGMT, hMLH1 and hMLH2 genes either in cancer or remote normal-appearing tissues. Aberrant hypermethylation of P16, MGMT, hMLH1 and hMLH2 could be predictive of gastric cancer.

• Molecules and Cells
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• v.40 no.1
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• pp.45-53
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• 2017

Aberrant hypermethylation of Wnt antagonists has been observed in gastric cancer. A number of studies have focused on the hypermethylation of a single Wnt antagonist and its role in regulating the activation of signaling. However, how the Wnt antagonists interacted to regulate the signaling pathway has not been reported. In the present study, we systematically investigated the methylation of some Wnt antagonist genes (SFRP2, SFRP4, SFRP5, DKK1, DKK2, and APC) and their regulatory role in carcinogenesis. We found that aberrant promoter methylation of SFRP2, SFRP4, DKK1, and DKK2 was significantly increased in gastric cancer. Moreover, concurrent hypermethylation of SFRP2 and DKK2 was observed in gastric cancer and this was significantly associated with increased expression of ${\beta}-catenin$, indicating that the joint inactivation of these two genes promoted the activation of the Wnt signaling pathway. Further analysis using a multivariate Cox proportional hazards model showed that DKK2 methylation was an independent prognostic factor for poor overall survival, and the predictive value was markedly enhanced when the combined methylation status of SFRP2 and DKK2 was considered. In addition, the methylation level of SFRP4 and DKK2 was correlated with the patient's age and tumor differentiation, respectively. In conclusion, epigenetic silencing of Wnt antagonists was associated with gastric carcinogenesis, and concurrent hypermethylation of SFRP2 and DKK2 could be a potential marker for a prognosis of poor overall survival.

• Tuberculosis and Respiratory Diseases
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• v.64 no.4
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• pp.285-292
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• 2008

Background: A diagnosis of malignant pleural effusion is clinically important, as the prognosis of lung cancer patients with malignant pleural effusion is poor. The diagnosis will be difficult if a cytological test is negative. This study was performed to investigate whether the detection of hypermethylation of the p16 (CDKN2A) and retinoic acid receptor b2 (RARB2) genes in pleural fluid is useful for a diagnosis of malignant pleural effusion. Methods: Pleural effusion was collected from 43 patients and was investigated for the aberrant promoter methylation of the RARB2 and CDKN2A genes by use of methylation-specific PCR. Results were compared with findings from a pleural biopsy and from pleural fluid cytology. Results: Of 43 cases, 17 cases of pleural effusion were due to benign diseases, and 26 cases were from lung cancer patients with malignant pleural effusion. Hypermethylation of the RARB2 and CDKN2A genes was not detected in the case of benign diseases, independent of whether or not the patients had ever smoked. In 26 cases of malignant pleural effusion, hypermethylation of RARB2, CDKN2A or either of these genes was detected in 14, 5 and 15 cases, respectively. The sensitivities of a pleural biopsy, pleural fluid cytology, hypermethylation of RARB2, hypermethylation of CDKN2A, or hypermethylation of either of the genes were 73.1%, 53.8%, 53.8%, 19.2%, and 57.7%, respectively; negative predictive values were 70.8%, 58.6%, 58.6%, 44.7%, and 60.7%, respectively. If both genes are considered together, the sensitivity and negative predictive value was lower than that for a pleural biopsy, but higher than that for pleural fluid cytology. The sensitivity of hypermethylation of the RARB2 gene for malignant pleural effusion was lower in small cell lung cancers than in non-small cell lung cancers. Conclusion: These results demonstrate that detection of hypermethylation of the RARB2 and CDKN2A genes showed a high specificity, and sensitivity was higher than for pleural fluid cytology. With a better understanding of the pathogenesis of lung cancer according to histological types at the molecular level, and if appropriate genes are selected for hypermethylation testing, more precise results may be obtained.