Antitumor Effects of a Sirtuin Inhibitor, Tenovin-6, against Gastric Cancer Cells via Death Receptor 5 Up-Regulation

Up-regulated sirtuin 1 (SIRT1), an NAD+-dependent class III histone deacetylase, deacetylates p53 and inhibits its transcriptional activity, leading to cell survival. SIRT1 overexpression has been reported to predict poor survival in some malignancies, including gastric cancer. However, the antitumor effect of SIRT1 inhibition remains elusive in gastric cancer. Here, we investigated the antitumor mechanisms of a sirtuin inhibitor, tenovin-6, in seven human gastric cancer cell lines (four cell lines with wild-type TP53, two with mutant-type TP53, and one with null TP53). Interestingly, tenovin-6 induced apoptosis in all cell lines, not only those with wild-type TP53, but also mutant-type and null versions, accompanied by up-regulation of death receptor 5 (DR5). In the KatoIII cell line (TP53-null), DR5 silencing markedly attenuated tenovin-6-induced apoptosis, suggesting that the pivotal mechanism behind its antitumor effects is based on activation of the death receptor signal pathway. Although endoplasmic reticulum stress caused by sirtuin inhibitors was reported to induce DR5 up-regulation in other cancer cell lines, we could not find marked activation of its related molecules, such as ATF6, PERK, and CHOP, in gastric cancer cells treated with tenovin-6. Tenovin-6 in combination with docetaxel or SN-38 exerted a slight to moderate synergistic cytotoxicity against gastric cancer cells. In conclusion, tenovin-6 has potent antitumor activity against human gastric cancer cells via DR5 up-regulation. Our results should be helpful for the future clinical development of sirtuin inhibitors

Proton Beam Therapy for Large Hepatocellular Carcinoma

PurposeTo investigate the safety and efficacy of proton beam therapy (PBT) in patients with large hepatocellular carcinoma (HCC).Methods and MaterialsTwenty-two patients with HCC larger than 10 cm were treated with proton beam therapy at our institution between 1985 and 2006. Twenty-one of the 22 patients were not surgical candidates because of advanced HCC, intercurrent disease, or old age. Median tumor size was 11 cm (range, 10–14cm), and median clinical target volume was 567 cm3 (range, 335–1,398 cm3). Hepatocellular carcinoma was solitary in 18 patients and multifocal in 4 patients. Tumor types were nodular and diffuse in 18 and 4 patients, respectively. Portal vein tumor thrombosis was present in 11 patients. Median total dose delivered was 72.6 GyE in 22 fractions (range, 47.3–89.1 GyE in 10–35 fractions).ResultsThe median follow-up period was 13.4 months (range, 1.5–85 months). Tumor control rate at 2 years was 87%. One-year overall and progression-free survival rates were 64% and 62%, respectively. Two-year overall and progression-free survival rates were 36% and 24%, respectively. The predominant tumor progression pattern was new hepatic tumor development outside the irradiated field. No late treatment-related toxicity of Grade 3 or higher was observed.ConclusionsThe Bragg peak properties of PBT allow for improved conformality of the treatment field. As such, large tumor volumes can be irradiated to high doses without significant dose exposure to surrounding normal tissue. Proton beam therapy therefore represents a promising modality for the treatment of large-volume HCC. Our study shows that PBT is an effective and safe method for the treatment of patients with large HCC

Long-term outcomes of proton beam therapy in patients with previously untreated hepatocellular carcinoma

Long-term efficacy of proton beam therapy (PBT) remains unclear for patients with previously untreated hepatocellular carcinoma (HCC). We aimed to study the long-term outcomes of PBT according to Barcelona Clinic Liver Cancer (BCLC) staging classifications in patients with previously untreated HCC. The major eligibility criteria of this observational study were an Eastern Cooperative Oncology Group performance status (PS) 0–2, Child–Pugh grade A or B, previously untreated HCC covered within an irradiation field, and no massive ascites. A total of 66.0–77.0 GyE was administered in 10–35 fractions. Local tumor control (LTC), defined as no progression in the irradiated field, progression-free survival (PFS), and overall survival (OS) were assessed according to BCLC staging. From 2002 to 2009 at our institution, 129 patients were eligible. The 5-year LTC, PFS, and OS rates were 94%, 28%, and 69% for patients with 0/A stage disease (n = 9/21), 87%, 23%, and 66% for patients with B stage disease (n = 34), and 75%, 9%, and 25% for patients with C stage disease (n = 65), respectively. The 5-year LTC and OS rates of 15 patients with tumor thrombi in major vessels were 90% and 34%, respectively. Multivariate analyses revealed that PS (0 versus 1–2) was a significant prognostic factor for OS. No grade 3 or higher adverse effects were observed. PBT showed favorable long-term efficacies with mild adverse effects in BCLC stage 0 to C, and can be an alternative treatment for localized HCC especially when accompanied with tumor thrombi. This study was registered with UMIN Clinical Trials Registry (UMIN000025342)

腫瘍融解ワクシニアウイルスの肝癌幹細胞に対する殺細胞効果の評価

科学研究費助成事業 研究成果報告書：基盤研究(C)2013-2015課題番号 : 2546097

ヒト カン ノ GLUTATHIONE S TRANSFERASE GST アイソザイム ニ カンスル キソテキ リンシヨウテキ ケンキユウ

Glutathione S-transferase(以下、ＧＳＴ）は、肝をはじめ広く生体内に存在し、多くの薬剤、生体外異物とGluthathione(以下、ＧＳＨ）との抱合等、種々の解毒機構に関連した酵素であり、また、ビリルビンをはじめとする各種有機陰イオンの細胞内結合蛋白である（1-14)。本章では、本酵素蛋白に関する基礎的ならびに臨床的研究の現況について概説しつつ、本研究の目的について述べる。筑波大学医学博士学位論文・平成元年3月25日授与 (甲第673号)付:参考論