Ken Gyobu

Hypomethylation of Alu repetitive elements in esophageal mucosa, and its potential contribution to the epigenetic field for cancerization

BackgroundAberrant 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.MethodWe 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.ResultsMethylation 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.ConclusionThis 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.

Influence of incomplete neoadjuvant chemotherapy on esophageal carcinoma

BackgroundNeoadjuvant chemotherapy (NAC) involving two cycles of cisplatin plus fluorouracil is recommended in Japan as a standard treatment for resectable, locally advanced esophageal squamous cell carcinoma (ESCC). We have encountered patients who were administered incomplete chemotherapy because of adverse events or the patient’s refusal of treatment. Here, we retrospectively investigated the influence on perioperative outcomes and long-term prognosis of patients with ESCC who underwent complete (two cycles) or incomplete (one cycle) NAC.MethodsWe retrospectively investigated 133 patients with locally advanced ESCC of the thoracic esophagus who underwent NAC. We compared the perioperative results and prognoses of patients who underwent complete or incomplete NAC because of adverse events or the patient’s refusal of treatment.ResultsOf 133 patients, 37 patients did not receive the second cycle of NAC; the remaining 96 patients received the second cycle of NAC as scheduled. There were no significant differences in the clinical backgrounds, surgical results, or operative morbidity rates between the groups. Patients in both groups were similarly administered postoperative chemotherapy regimens. There was no significant difference in disease-free survival or overall survival.ConclusionsWe suggest that perioperative outcomes and long-term prognosis of patients with locally advanced ESCC were not significantly influenced, even if the patients did not receive a complete cycle of NAC. When certain adverse events occur after the first cycle of NAC, we believe that it is nevertheless possible to discontinue chemotherapy.

Abstract 5375: Androgen excess induces aberrant DNA methylation in the prostate.

Aberrant DNA methylation is deeply involved in prostate carcinogenesis. However, inducers of aberrant DNA methylation in the prostate are almost unknown. Here, we investigated whether androgen excess can induce aberrant DNA methylation or not, using a rat prostate cancer model. First, by analysis of reported data of expression microarray after treatment of a prostate cancer cell line with a demethylating agent, we isolated two marker genes (Mmp23, Nkx3.1) whose promoter CpG islands were aberrantly methylated in testosterone and 3,2′-dimethyl-4-aminobiphenyl-induced invasive adenocarcinomas. These two genes and three genes previously isolated (Aebp1, Amn1, Tgfbr2) [Yamashita et al. Cancer Res. 2008] were used as markers. Then, we analyzed temporal profiles of DNA methylation levels of the five genes in the dorsolateral lobe of rats treated with excessive androgen. Testosterone was administrated every five weeks for 15, 30, 40 and 50 weeks from six weeks old by subcutaneous implantation of a Silastic tube containing 40 mg testosterone propionate. Aberrant DNA methylation of two genes (Amn1, Mmp23) was gradually induced during the testosterone treatment while that of the other three genes was not. The former two genes had lower mRNA expression levels in the normal prostate than the latter three genes, which was in accordance with the known fact that genes with low transcription are susceptible to DNA methylation. Third, we investigated molecular mechanisms for aberrant DNA methylation induction by androgen excess. Androgen excess did not induce mRNA expression of DNA methyltransferases; Dnmt1, Dnmt3a or Dnmt3b in the rat prostrate. As for histone modifications, it did not induce significant changes in either H3K4me3 or H3K27me3 levels of the five genes methylated in rat prostate cancer. In contrast, it induced infiltration of lymphocytes and neutrophils in the prostate. Temporal profiles of expression levels of specific inflammation-related genes (Cxcl2, Il1b, Nos2 and Tnf) paralleled the methylation levels of Amn1 and Mmp23. Androgen excess did not induce bacterial infection as determined by copy number of bacterial DNA, but induced increase in Ki67-positive cells in regions with and without infiltration of inflammatory cells. The inflammatory response, known as a major mechanism for aberrant DNA methylation induction, along with cell proliferation was likely to be the cause of aberrant DNA methylation induction in the rat prostate with androgen excess. These results demonstrated that androgen excess can induce aberrant DNA methylation in the prostate, and suggested that inflammatory response underlies aberrant DNA methylation induction by androgen excess. Citation Format: Satoshi Yamashita, Satoru Takahashi, Yasunori Matsuda, Ken Gyobu, Toshikazu Ushijima. Androgen excess induces aberrant DNA methylation in the prostate. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5375. doi:10.1158/1538-7445.AM2013-5375

Effect of Neutrophil Elastase Inhibitor on Coagulability in Patients after Radical Esophagectomy

食道癌術後には凝固異常が発症することが知られている。この凝固異常に対しては，現在までステロイドなどさまざまな薬剤投与が試みられてきた。今回われわれは，好中球エラスターゼの特異的阻害剤（シベレスタットナトリウム，以下SN）投与の食道癌術後の凝固能におよぼす影響について検討した。対象は食道癌切除再建を一期的に行った41例で，これら症例を術後SNを投与した21例（SN+群）と，SNを投与しなかった20例（SN-群）に分けた。SN+群でSNを，術直後より0.2mg/kg/hrで術5病日まで持続的に投与した。全例で術直前にメチルプレドニゾロン（500mg）を投与し，術7病日まで血小板数・FBG·FDP·D-Dimer·AT3·TAT·APTT·Protein C・α2PIを経時的に測定した。血小板数・FBG·FDP·D-Dimer·TATの変動には両群に差がなかった。AT3とProtein Cは術2·3病日でSN+群が有意に高値で，α2PIは術3病日でSN+群が有意に高値であった。APTTは，術3病日にSN-群で有意に高かった。食道癌術後管理におけるエラスターゼ阻害剤投与は食道癌術後の凝固異常状態を制御し，早期に回復させることが可能である。