[show abstract][hide abstract] ABSTRACT: Contamination of normal cells is almost always present in tumor samples and affects their molecular analyses. DNA methylation, a stable epigenetic modification, is cell type-dependent, and different between cancer and normal cells. Here, we aimed to demonstrate that DNA methylation can be used to estimate the fraction of cancer cells in a tumor DNA sample, using esophageal squamous cell carcinoma (ESCC) as an example. First, by an Infinium HumanMethylation450 BeadChip array, we isolated three genomic regions (TFAP2B, ARHGEF4, and RAPGEFL1) i) highly methylated in four ESCC cell lines, ii) hardly methylated in a pooled sample of non-cancerous mucosae, a pooled sample of normal esophageal mucosae, and peripheral leukocytes, and iii) frequently methylated in 28 ESCCs (TFAP2B, 24/28; ARHGEF4, 20/28; and RAPGEFL1, 19/28). Second, using eight pairs of cancer and non-cancer cell samples prepared by laser capture microdissection, we confirmed that at least one of the three regions was almost completely methylated in ESCC cells, and all the three regions were almost completely unmethylated in non-cancer cells. We also confirmed that DNA copy number alterations of the three regions in 15 ESCC samples were rare, and did not affect the estimation of the fraction of cancer cells. Then, the fraction of cancer cells in a tumor DNA sample was defined as the highest methylation level of the three regions, and we confirmed a high correlation between the fraction assessed by the DNA methylation fraction marker and the fraction assessed by a pathologist (r=0.85; p<0.001). Finally, we observed that, by correction of the cancer cell content, CpG islands in promoter regions of tumor-suppressor genes were almost completely methylated. These results demonstrate that DNA methylation can be used to estimate the fraction of cancer cells in a tumor DNA sample.
PLoS ONE 01/2013; 8(12):e82302. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Aberrant hypermethylation of specific genes is present in esophageal squamous cell carcinomas (ESCCs). Such hypermethylation is also present in normal-appearing esophageal mucosae of ESCC patients and is considered to contribute to the formation of a field for cancerization. On the other hand, the presence of global hypomethylation in ESCCs or in their background esophageal mucosae is unknown.
We collected 184 samples of esophageal mucosae (95 normal mucosae from healthy subjects, and 89 non-cancerous background mucosae from ESCC patients) and 93 samples of ESCCs. Methylation levels of repetitive elements (Alu, LINE1) and cancer/testis antigen genes (NY-ESO-1, MAGE-C1) were measured by bisulfite pyrosequencing and quantitative methylation-specific PCR, respectively.
Methylation levels of Alu, LINE1, NY-ESO-1, and MAGE-C1 were significantly lower in ESCCs than in their background and normal mucosae. Also, in the background mucosae, a significant decrease of the Alu methylation level compared with the normal mucosae was present. In ESCCs, methylation levels of the two repetitive elements and the two cancer/testis antigen genes were correlated with each other.
This is the first study to show the presence of global hypomethylation in ESCCs, and even in their non-cancerous background mucosae. Alu hypomethylation might reflect the severity of an epigenetic field for cancerization.
Cancer Causes and Control 04/2012; 23(6):865-73. · 3.20 Impact Factor
[show abstract][hide abstract] ABSTRACT: We quantified field cancerization of squamous cell carcinoma in the upper aerodigestive tract with epigenetic markers and evaluated their performance for risk assessment. Methylation levels were analyzed by quantitative methylation-specific PCR of biopsied specimens from a training set of 255 patients and a validation set of 224 patients. We also measured traditional risk factors based on demographics, lifestyle, serology, genetic polymorphisms, and endoscopy. The methylation levels of four markers increased stepwise, with the lowest levels in normal esophageal mucosae from healthy subjects without carcinogen exposure, then normal mucosae from healthy subjects with carcinogen exposure, then normal mucosae from cancer patients, and the highest levels were in cancerous mucosae (P < 0.05). Cumulative exposure to alcohol increased methylation of homeobox A9 in normal mucosae (P < 0.01). Drinkers had higher methylation of ubiquitin carboxyl-terminal esterase L1 and metallothionein 1M (P < 0.05), and users of betel quid had higher methylation of homeobox A9 (P = 0.01). Smokers had increased methylation of all four markers (P < 0.05). Traditional risk factors allowed us to discriminate between patients with and without cancers with 74% sensitivity (95% CI: 67%-81%), 74% specificity (66%-82%), and 80% area under the curve (67%-91%); epigenetic markers in normal esophageal mucosa had values of 74% (69%-79%), 75% (67%-83%), and 83% (79%-87%); and both together had values of 82% (76%-88%), 81% (74%-88%), and 91% (88%-94%). Epigenetic markers done well in the validation set with 80% area under the curve (73%-85%). We concluded that epigenetics could improve the accuracies of risk assessment.
Cancer Prevention Research 09/2011; 4(12):1982-92. · 4.89 Impact Factor
[show abstract][hide abstract] ABSTRACT: More than 15 years have passed since thoracoscopic surgery was first employed in Japan as a treatment for esophageal cancer with curative intent. Because of the proliferation of techniques that can be used to obtain an adequate operative field, such as hand assist, placing the patient in the prone position, etc., the number of approaches to thoracoscopic surgery has been increasing, contrary to expectations of standardization. The technique of mediastinal dissection has been refined with increasing knowledge of microanatomy, which can be clarified under the magnified view provided in thoracoscopic surgery. Comparable pulmonary function and survival are achieved after both thoracoscopic surgery and open-chest surgery. The accreditation board of the Japan Society for Endoscopic Surgery is now standardizing the thoracoscopic technique. To avoid surgical mistakes, thorough knowledge and adherence to the proper indications are essential.
[show abstract][hide abstract] ABSTRACT: The presence of lymph node metastasis in esophageal squamous cell carcinoma (ESCC) patients is a critical factor for decision of treatment strategy. However, there have been no molecular markers to assess lymph node metastasis. In this study, we aimed to identify CpG islands (CGIs) whose DNA methylation statuses are associated with the presence of lymph node metastasis.
A total of 96 ESCCs were divided into a screening set (n = 48) and a validation set (n = 48). Genome-wide methylation analysis was performed by methylated DNA immunoprecipitation-CGI microarray analysis. Methylation levels were analyzed by quantitative methylation-specific PCR (qMSP).
Genome-wide methylation analysis identified 25 CGIs differentially methylated between 8 ESCCs with lymph node metastasis and 4 without. In the screening set, 7 CGIs had significantly different methylation levels (P < 0.05) between the ESCCs with and without lymph node metastasis, and cut-off methylation levels for these CGIs were determined. The validation set was analyzed with the prefixed cut-offs, and methylation statuses of 2 CGIs in the vicinities of PAX6 and ENST00000363328 were validated to be associated with the presence of lymph node metastasis. Using these 2 markers, the presence was predicted with a sensitivity of 93% and specificity of 57%. In addition, the methylation statuses of the 2 CGIs were significantly associated with disease-free survival (P = 0.006).
Methylation statuses of these 2 CGIs were significantly associated with the presence of lymph node metastasis of ESCCs. These CGIs are promising markers to predict the presence of lymph node metastases.
Annals of Surgical Oncology 11/2010; 18(4):1185-94. · 4.12 Impact Factor
[show abstract][hide abstract] ABSTRACT: A 77-year-old male with thoracic esophageal cancer (cT3N3M0, Stage III) received nedaplatin at 80mg/m2 for 1 day and 5-fluorouracil at 800mg/m2 for 5 days as neoadjuvant treatment. On the fifth day of treatment, he lapsed into a coma (Japan Coma Scale 30), and his serum sodium concentration was found to be decreased to 116mEq/L. We concluded hyponatremia due to SIADH (syndrome of inappropriate secretion of antidiuretic hormone) induced by chemotherapy based on the fact that the patient had no finding of dehydration, particular history of related disorders, serum hypoosmolality accompanied by urine hyperosmolality and persistent urinary sodium excretion. We treated him with fluid restriction, sodium supplement and administration of loop diuretic. Then he regained consciousness and appropriate serum sodium level. Thereafter, hyponatremia was corrected without recurrence, and the patient underwent radical esophagectomy safely. He has been in good condition without recurrence of esophageal cancer after surgery.
Gan to kagaku ryoho. Cancer & chemotherapy 09/2010; 37(9):1787-90.