• 한국환경성돌연변이발암원학회지
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• 제25권3호
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• pp.87-96
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• 2005

[ $p16^{INK4a}$ ] is a tumor suppressor that belongs to the INK4 family of the cyclin D-dependent kinases (cdk) inhibitors. It plays regulatory roles in cell proliferation and in tumorigenesis by interacting with Rb signaling. Abnormally elevated $p16^{INK4a}$ protein expression causes cell cycle arrest (G1/S transition) and loss of cyclin-cdk activity. In many cancers, $p16^{INK4a}$ is altered by mutation, deletion, and promoter methylation. This review summarizes the function of p16 as an important regulator of cancer pathobiology and a promising target fer developing cancer therapeutic and chemopreventive agents.

• Asian Pacific Journal of Cancer Prevention
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• 제15권9호
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• pp.3921-3925
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• 2014

RASSF1A has been reported to be a candidate tumor suppressor in esophageal squamous cell carcinoma (ESCC). However, the association between RASSF1A promoter methylation and ESCC remains unclear. Eligible studies were identified through searching PubMed, Medline, Web of Science, and the China National Knowledge Infrastucture database. Studies were pooled and odds ratios (ORs) with corresponding confidence intervals (CIs) were calculated. Funnel plots were also performed to evaluate publication bias. Twelve studies involving 859 cases and 675 controls were included in this meta-analysis. A significant association was observed between RASSF1A methylation and ESCC overall (OR = 11.7, 95% CI: 6.59-20.9, z=8.36, P<0.00001). Subgroup analysis showed that the OR for heterogeneous tissues was 5.35 (95% CI = 2.95-9.71) while for autologous tissues it was 16.0 (8.31-30.96). For patient sample size, the OR for the <50 subgroup was 9.92 (95% CI = 2.88-34.2) and for the 50 case group was 13.1 (95% CI = 6.59-25.91). The OR for a relationship between RASSF1A methylation and TNM stages was 0.27 (95% CI=0.10-0.77), whereas there were no significant differences in RASSF1A methylation in relation to gender and differentiation among ESCC cases. This meta-analysis suggests a significant association between RASSF1A methylation and ESCC.

• Asian Pacific Journal of Cancer Prevention
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• 제15권16호
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• pp.6745-6748
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• 2014

Background: Nowadays, molecular biomarkers have critical roles for cancer diagnosis and prognosis in clinical laboratories. Human papillomaviruses are the main agents for etiology of cervical carcinoma. The present survey was conducted to evaluate the genes methylation in cervical cancer and precancerous lesions involvement with HPV genotypes. Materials and Methods: C13orf18 and C10rf166 (MULl or Mulan) DNA methylation as potential biomarkers and risk factors was investigated in 112 liquid based cytology and Formalin-Fixed Paraffin-Embedded tissue specimens in Iranian females with cervical intraepithelial neoplasia and dysplasia. Results: In this survey, HPV18 (61.6%) and HPV16 (42.9%) proved to be the most common HPV genotypes identified by In-House Multiplex Real Time PCR. There were no significant relationship between HPV positivity and the methylated DNA genes mentioned above (p>0.05). Conclusions: Our MethyLight data demonstrated that these genes could not be considered as specific, sensitive and suitable prognostic biomarkers in cervical dysplasia related HPV. It is suggested that further studies with more patients should be done on candidate methylated markers in different countries in order to plan for cervical cancer prevention.

• Reproductive and Developmental Biology
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• 제31권2호
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• pp.83-90
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• 2007

Insulin-like growth factor II (IGF2) and H19 genes are mutually imprinted genes which may be responsible for abnormalities in the cloned fetuses and offspring. This study was performed to identify putative differentially methylated regions (DMRs) of porcine H19 locus and to explore its genomic imprinting in in vitro fertilized (IVF) and somatic cell nuclear transferred (SCNT) embryos. Based on mice genomic data, we identified DMRs on H19 and found porcine H19 DMRs that included three CTCF binding sites. Methylation patterns in IVF and SCNT embryos at the 2-, 4-, $8{\sim}16$-cells and blastocyst stages were analyzed by BS (Bisulfite Sequencing)-PCR. The CpGs in CTCF1 was significantly unmethylated in the 2-cell stage IVF embryos. However, the 4- (29.1%) and $8{\sim}16$-cell (68.2%) and blastocyst (48.2%) stages showed higher methylation levels (p<0.01). On the other hand, SCNT embryos were unmethylayted ($0{\sim}2%$) at all stages of development. The CpGs in CTCF2 showed almost unmethylation levels at the 2-,4- and $8{\sim}16$-cell and blastocyst stages of development in both IVF ($0{\sim}14.1%$) and SCNT ($0{\sim}6.4%$) embryos. At all stages of development, CTCF3 was unmethylated in IVF ($0{\sim}17.3%$) and SCNT ($0{\sim}1.2%$) embryos except at the blastocyst stage (54.5%) of IVF embryos. In conclusion, porcine SCNT embryos showed an aberrant methylation pattern comprised to IVF embryos. Therefore, we suggest that the aberrant methylation pattern of H19 loci may be a reason for increased abnormal fetus after embryo transfer of porcine SCNT embryos.

• Asian Pacific Journal of Cancer Prevention
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• 제16권4호
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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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• 제16권4호
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• pp.1599-1603
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• 2015

Background: Epigenetic silencing of tumor suppressor genes due to promoter hypermethylation is one of the frequent mechanisms observed in cancers. Hypermethylation of several tumor suppressor genes involved in cell cycle regulation has been reported in many types of tumors including oral squamous cell carcinomas. LATS1 (Large Tumor Suppressor, isoform 1) is a novel tumor suppressor gene that regulates cell cycle progression by forming complexes with the cyclin dependent kinase, CDK1. Promoter hypermethylation of the LATS1 gene has been observed in several carcinomas and also has been linked with prognosis. However, the methylation status of LATS1 in oral squamous cell carcinomas is not known. As oral cancer is one of the most prevalent forms of cancer in India, the present study was designed to investigate the methylation status of LATS1 promoter and associate it with histopathological findings in order to determine any associations of the genetic status with stage of differentiation. Materials and Methods: Tumor chromosomal DNA isolated from biopsy tissues of thirteen oral squamous cell carcinoma biopsy tissues were subjected to digestion with methylation sensitive HpaII enzyme followed by amplification with primers flanking CCGG motifs in promoter region of LATS1 gene. The PCR amplicons were subsequently subjected to agarose gel electrophoresis along with undigested amplification control. Results: HpaII enzyme based methylation sensitive PCR identified LATS1 promoter hypermethylation in seven out of thirteen oral squamous cell carcinoma samples. Conclusions: The identification of LATS1 promoter hypermethylation in seven oral squamous cell carcinoma samples (54%), which included one sample with epithelial dysplasia, two early invasive and one moderately differentiated lesions indicates that the hypermethylation of this gene may be one of the early event during carcinogenesis. To the best of our knowledge, this is the first study to have explored and identified positive association between LATS1 promoter hypermethylation with histopathological features in oral squamous cell carcinomas.

• Journal of Gastric Cancer
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• 제13권4호
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• pp.232-241
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• 2013

Purpose: Gastrokine 1 plays an important role in gastric mucosal defense. Additionally, the Gastrokine 1-miR-185-DNMT1 axis has been shown to suppress gastric carcinogenesis through regulation of epigenetic alteration. Here, we investigated the effects of Gastrokine 1 on DNA methylation and gastritis. Materials and Methods: Expression of Gastrokine 1, DNMT1, EZH2, and c-Myc proteins, and the presence of Helicobacter pylori CagA protein were determined in 55 non-neoplastic gastric mucosal tissue samples by western blot analysis. The CpG island methylation phenotype was also examined using six markers (p16, hMLH1, CDH1, MINT1, MINT2 and MINT31) by methylation-specific polymerase chain reaction. Histological gastritis was assessed according to the updated Sydney classification system. Results: Reduced Gastrokine 1 expression was found in 20 of the 55 (36.4%) gastric mucosal tissue samples and was closely associated with miR-185 expression. The Gastrokine 1 expression level was inversely correlated with that of DNMT1, EZH2, and c-Myc, and closely associated with the degree of gastritis. The H. pylori CagA protein was detected in 26 of the 55 (47.3%) gastric mucosal tissues and was positively associated with the expression of DNMT1, EZH2, and c-Myc. In addition, 30 (54.5%) and 23 (41.9%) of the gastric mucosal tissues could be classified as CpG island methylation phenotype-low and CpG island methylation phenotype-high, respectively. Reduced expression of Gastrokine 1 and miR-185, and increased expression of DNMT1, EZH2, and c-Myc were detected in the CpG island methylation phenotype-high gastric mucosa. Conclusions: Gastrokine 1 has a crucial role in gastric inflammation and DNA methylation in gastric mucosa.

• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8287-8292
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• 2016

Background: Thymidylate synthase (TS) catalyzes the methylation of deoxyuridylate to deoxythymidylate and is involved in DNA methylation, synthesis and repair. Two common polymorphisms have been reported, tandem repeats in the promoter-enhancer region (TSER), and 6bp ins/del in the 5'UTR, that are implicated in a number of human diseases, including cancer. The association between the two polymorphisms in risk for lung cancer (LC) was here investigated in the Jordanian population. Materials and Methods: An age, gender, and smoking-matched case-control study involving 84 lung cancer cases and 71 controls was conducted. The polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP) technique was used to detect the polymorphism of interest. Results: Individuals bearing the ins/ins genotype were 2.5 times more likely to have lung cancer [(95%CI: 0.98-6.37), p=0.051]. Individuals who were less than or equal to 57 years and carrying ins/ins genotype were 4.6 times more susceptible to lung cancer [OR<57 vs >57years: 4.6 (95%CI: 0.93-22.5), p=0.059)]. Genotypes and alleles of TSER were distributed similarly between cases and controls. Weak linkage disequilibrium existed between the two loci of interest (Lewontin's coefficient [D']) (LC: D' =0.03, r2: 0. 001, p=0.8; Controls: D' =0.29, r2: 0.08, p=0.02). Carriers of the "3 tandem repeats_insertion" haplotype (3R_ins) were 2 times more likely to have lung cancer [2 (95%CI: 1.13-3.48), p=0.061]. Conclusions: Genetic polymorphism of TS at 3 'UTR and its haplotype analysis may modulate the risk of lung cancer in Jordanians. The 6bp ins/del polymorphism of TS at 3 'UTR is more informative than TSER polymorphism in predicting increased risk.

• Tuberculosis and Respiratory Diseases
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• 제64권4호
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• pp.285-292
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• 2008

연구배경: 악성 흉수가 있는 환자는 예후가 좋지 않아 이를 감별하는 것은 임상적으로 중요한 일이다. 하지만 흉수 내 세포진 검사가 음성일 경우 진단이 쉽지 않다. 따라서 본 연구는 흉수 탈락 세포에서 추출한 DNA에서 종양억제 유전자로 알려진 retinoic acid receptor b2 (RARB2)와 p16 유전자의 과메틸화 측정이 악성 흉수 진단에 도움이 될 수 있을지를 확인하기 위하여 실시하였다. 방법: 43명의 환자에서 흉수를 천자하여 흉수 내 탈락 세포에서 메틸화 특이 PCR 방법으로 RARB2와 p16 유전자의 과메틸화를 측정하고, 이를 흉막 생검 및 흉수 세포진 검사법과 비교하였다. 결과: 43명의 환자 중 17명은 폐렴, 결핵에 의한 양성 흉수 환자였고, 26명은 흉막 침범 폐암 환자였다. 17명의 양성 흉수에서는 흡연 유무와 상관없이 RARB2와 p16 유전자의 과메틸화가 관찰되지 않았다. 26명의 악성 흉수에서 과메틸화는 각각 14명, 5명에서 관찰되었으며, 두 유전자 중 어느 한 쪽이라도 과메틸화가 생긴 경우는 15명이었다. 흉막 생검, 흉수 내 세포진 검사, RARB2 단독, p16 단독, 두 유전자 동시 측정 과메틸화 검사의 민감도는 각각 73.1%, 53.8%, 53.8%, 19.2%, 57.7%이었고, 음성 예측도는 각각 70.8%, 58.6%, 58.6%, 44.7%, 60.7%로서 두 유전자를 동시에 검사할 때의 민감도와 음성 예측도는 흉막 생검보다는 낮았지만, 흉수 내 세포진 검사보다는 높았다. 또, 소세포암에서 p16를 이용한 민감도가 14.3%로 떨어져서 조직 유형에 따른 차이를 보였다. 결론: 본 연구 결과에서 p16과 RARB2 유전자의 과메틸화의 발견은 악성 흉수를 양성과 감별하는데 높은 특이도를 보였고, 민감도 역시 흉수 내 세포진 검사보다 높은 방법이었다. 폐암의 세포 유형에 따른 분자 생물학적 병리를 이해하고 적절한 유전자를 선정한다면 이런 결과는 더욱 향상될 수 있을 것으로 생각된다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권11호
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• pp.4539-4543
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• 2014

Since the epigenetic alteration in tumor cells can be reversed by the dietary polyphenol quercetin (Q) or butyrate (B) with chemopreventive activity, suggesting that Q or B can be used for chemopreventive as well as therapeutic agent against tumors. In this study the polyphenol flavonoid quercetin (Q) or sodium butyrate (B) suppressed human esophageal 9706 cancer cell growth in dose dependent manner, and Q combined with B (Q+B) could further inhibit Eca9706 cell proliferation than that induced by Q or B alone, compared with untreated control group (C) in MTT assay. The reverse expressions of global DNMT1, $NF-{\kappa}Bp65$, HDAC1 and Cyclin D1 were down-regulated, while expressions of caspase-3 and $p16INK4{\alpha}$ were up-regulated, compared with the C group in immunoblotting; the down-regulated HDAC1-IR (-immunoreactivity) with nuclear translocation, and up-regulated E-cadherin-IR demonstrated in immunocytochemistry treated by Q or B, and Q+B also displayed further negatively and positively modulated effects compared with C group. The order of methylation specific (MS) PCR of $p16INK4{\alpha}$: C>B/Q>Q+B group, while the order of E-cadherin expression level was contrary, Q+B>Q/B>C group. Thus, Q/B, especially Q+B display reverse effect targeting both altered DNA methylation and histone acetylation, acting as histone deacetylase inhibitor mediated via epigenetic-$NF-{\kappa}B$ cascade signaling.