Michio Kato

Expression of manganese superoxide dismutase in esophageal and gastric cancers

Abstract: The tumor-killing activity of radiotherapy and chemotherapy for cancer is closely associated with the production of active oxygen, and the relation between therapeutic resistance and active oxygen scavengers produced by the tumor itself is gaining more attention. It is considered that manganese superoxide dismutase (MnSOD) protects host cells from oxidative stress, in synergy with other antioxidant enzymes. In this study, we used a quantitative polymerase chain reaction assay to measure MnSOD mRNA in resected specimens from patients with esophageal and gastric cancers. In both esophageal and gastric cancers, the level of MnSOD mRNA was significantly elevated in cancer tissue compared to non-cancer tissue (P < 0.01). In gastric cancer tissue, the MnSOD mRNA level was significantly higher than in esophageal cancer tissue (P < 0.01). The significance of MnSOD in cancer tissue was investigated further by measuring MnSOD content in resected specimens using an enzyme-linked immunosorbent assay, and by examining its location by an immunohistochemical method. Upregulation of MnSOD in cancer tissue most likely serves as a protective mechanism against anti-cancer therapies known to produce superoxide radicals as a key component of their tumor-killing activity.

Induction of gene expression for immunomodulating cytokines in peripheral blood mononuclear cells in response to orally administered PSK, an immunomodulating protein-bound polysaccharide

The protein-bound polysaccharide extracted from a fungus, PSK, has been used as a biological response modifier in the treatment of cancer patients in Japan for over 16 years. The administration of PSK to tumor-bearing rodents inhibited tumor growth and modulated immune responses. Recently, an in vitro study has revealed that PSK is a strong inducer of cytokine gene expression and production in human peripheral blood mononuclear cells (PBMC). To establish whether PSK has cytokine-inducing activities in vivo, we have orally administered PSK (1 g, the clinical dose) to 12 healthy volunteers and 9 gastric cancer patients who had undergone gastrectomy, and assessed the gene expression for cytokines in PBMC of each subject. As determined by the reverse-transcribed polymerase chain reaction method, the induction of gene expression for both tumor necrosis factor α and interleukin-8 (IL-8) was detected in PBMC from 5 of the 12 healthy volunteers (42%) and 4 of the 9 patients (44%). Furthermore, the concentration of serum IL-8 was elevated in 5 healthy volunteers given PSK orally, who had shown induction of IL-8 gene expression, as detected by enzyme-linked immunosorbent assay. These findings indicate that responsiveness of PBMC to PSK, in terms of gene expression and production of cytokines, varies among individuals. Thus, when using PSK to treat cancer patients, it seems advisable to select patients on the basis of their responsiveness to PSK. We speculate that the cytokines induced by PSK might mediate the immunoenhancing action of this agent in vivo.

Preparation of poly-lactic acid microspheres containing the angiogenesis inhibitor TNP-470 with medium-chain triglyceride and the in vitro evaluation of release profiles

TNP-470 (AGM-1470, 6-0-(N-chloroacetylcarbamoyl)-fumagillol), a derivative of fumagillin, is a promising angiogenesis inhibitor. However, as TNP-470 is very unstable in in vitro and in vivo, it has been difficult to verify its pharmacological efficacy in the clinical medicine. The preparation of a drug delivery system (DDS) in a microsphere form was studied for the stable inclusion and controlled release of TNP-470. Medium-chain triglyceride (MCTG) as an effective stabilizer and poly-lactic acid (PLA) as a biodegradable carrier were used for this purpose. The release of TNP-470 from the MCTG containing DDS continued for approximately 2 weeks, while the release of TNP-470 from the one without MCTG stopped after only 5 days. It was proved that TNP-470 could be released much more stable for much longer period from the MCTG containing DDS compared to the one without DDS.

Massive bleeding from multiple jejunal diverticula associated with an angiodysplasia: Report of a case

We report herein the case of a 70-year-old woman who presented with massive bleeding from multiple jejunal diverticula. She was initially admitted to our hospital with massive melena. An upper gastrointestinal endoscopic examination revealed no bleeding site. Colonoscopy revealed clotted and red blood throughout the colon, and a small diverticulum in the ascending colon which was thought to be the source of bleeding. Following admission, she was treated conservatively at first, but melena continued and the anemia did not improve despite blood transfusions. A laparotomy was performed and multiple jejunal diverticula, distributed from 10 to 40cm distal to the ligament of Treitz, were found. A segment of the jejunum containing all diverticula was resected. The most distal diverticulum contained a clot of blood, but no ulceration was observed. A histological examination revealed many dilated blood vessels in the mucosa and submucosa of this diverticulum, which were compatible with the findings of angiodysplasia. Based on these findings, we believe that angiodysplasia was the cause of bleeding from the jejunal diverticula in this case.

Expression of manganese superoxide disumutase influences chemosensitivity in esophageal and gastric cancers

The purpose of this study was to examine whether the increased sensitivity of cancer cells to adriamycin (ADM), which is known to produce superoxide radicals, was brought through suppressed manganese superoxide disumutase (MnSOD) expression in the presence of transforming growth factor beta1 (TGFbeta1). T.T., MKN28, and MKN45 cell lines were treated with TGFbeta1 before exposure to ADM. Athymic female mice bearing the MKN28 cells were treated with TGFbeta1, ADM, or TGFbeta1 + ADM. Pretreatment of T.T., MKN28, and MKN45 cell lines with TGFbeta1 resulted in increased sensitivity to ADM. In contrast, simultaneous exposure to TNFalpha, which increased MnSOD expression, decreased sensitivity of cancer cells to ADM. In vivo studies demonstrated that the combined administration of TGFbeta1 and ADM delayed tumor growth better than either treatment alone. Our results suggest that the synergistic antitumor effects of TGFbeta1 and ADM may be due to decreased MnSOD expression in cancer cells. Thus, combined administration of TGFbeta1 and ADM might prove useful for treatment of malignant disease.

Experimental Studies on Potentiation of the Antitumor Activity of 5‐Fluorouracil with 3′‐Azido‐3‐deoxythymidine for the Gastric Cancer Cell Line MKN28 in vivo

A new method of biochemical modulation of 5‐fluorouracil (5‐FU) with 3‐azido‐3′‐deoxythymidine (AZT)was studied experimentally. Nude mice transplanted with cells of the human gastric cancer cell line MKN28 were divided into 4 groups, i.e., control, 5‐FU, AZT, and 5‐FU plus AZT, and the antitumor activities were compared. Based on the assessment of tumor volume, significant suppression of tumor growth was observed in the 5‐FU and 5‐FU plus AZT groups (P<0.05, P<0.01, versus control, respectively). The thymidylate synthase (TS) inhibition rate, an index of inhibition of the de novo pathway, was significantly higher in the 5‐FU and 5‐FU plus AZT groups than in the control group (P<0.01), but it did not differ from the control in the AZT group. TS‐bound FdUMP tended to be higher in the 5‐FU pins AZT group than in the 5‐FU group. The activity of thymidine kinase (TK) and the uptake ratio of 5‐hromo‐2′‐deoxyuridine (BrdU), indices of salvage pathway activity, were significantly lower in the AZT and 5‐FU plus AZT groups than in the control group (TK, P<0.05, P< 0.01; uptake ratio of BrdU, P< 0.01, P< 0.05, respectively). There were slight losses of body weight in the 5‐FU and 5‐FU plus AZT groups compared with that in the control group, but no difference between the AZT and control groups in weight loss. These findings suggest that addition of AZT plays an important role in potentiating the antitumor activity of 5‐FU through both blockage of a compensatory increase of activity in the salvage pathway and also an increase in TS‐bound FdUMP, anid has no adverse effects. Thus, the combination of 5‐FU and AZT could be useful as a new modality in gastric cancer chemotherapy.

Complete regression of recurrent esophageal carcinoma with reduced expression of glutathione S-transferase-π by treatment with continuous infusion of 5-fluorouracil and low-dose cisplatin infusion

The mortality rate of recurrent esophageal carcinoma remains high because of its resistance to chemotherapy and radiation therapy. We present a patient with recurrent esophageal carcinoma, which dramatically disappeared after treatment with the combination of continuous infusion of 5-fluorouracil and low-dose cis-Diamminedichloroplatinum-II (cisplatin) infusion (FP therapy). Furthermore, we immunohistologically found that glutathione S-transferases (GST)-π, a marker of resistance to cisplatin, was faintly expressed both in the endoscopical biopsy specimens of recurrent tumor and in the resected specimens of esophageal carcinoma and metastatic lymph nodes. FP therapy was suggested to be effective for recurrent esophageal carcinoma. Immunostaining for GST-π might be a prospective marker for the sensitivity of esophageal carcinoma to FP therapy, particularly cisplatin.

Gene Expression for Tumor Necrosis Factor a and Its Production in Gastric Cancer Patients

To determine the gene expression for tumor necrosis factor (TNF) a and its main site of production in gastric cancer patients, serum levels in the peripheral venous blood of 50 patients and the portal blood from 15 of these 50 patients were measured by enzyme‐linked immunosorbent assay (ELISA). TNF gene expression in the peripheral blood mononuclear cells (PBMC) and in the surgically resected tissues was then studied in 16 patients by reverse transcription‐polymerase chain reaction (RT‐PCR) assay. Whereas TNF mRNA expression was detected in the PBMC from 13 of 16 gastric cancer patients (81.3%), it was detected in only one tumor tissue (6.3%). Preoperatively, TNF was detected in the serum from 13 of 50 patients (26.0%). In the portal blood sampled immediately after laparotomy, TNF was positive in 4 of 15 patients (26.7%). TNF gene expression was much more frequently detected in PBMC than in other resected tissues, and its expression was higher than in the serum. Various clinicopathological factors for gastric cancer were not related to the prcopcrative detection of TNF in the serum. It appears that TNF is produced mainly in PBMC but not in the cancer regions or the regional lymph nodes of gastric cancer patients. It is suggested that TNF is not always secreted even when TNF mRNA is expressed, and its preoperatlve production is not related to tumor progression.

Effect and Action Mechanism of Prostaglandin E2 on Proliferation of Human Colon Cancer Cells in Culture

The effect of prostaglandin E2(PGE2) on the growth of human colon cancer cell line HT-29 was investigated. PGE2 significantly inhibited the growth of HT-29 cells without increasing cyclicAMP production. Furthermore, the proliferation of HT-29 cell was not suppressed by the administration of vasoactive intestinal peptide or dibutyryl cyclicAMP. The metabolism of PGE2 in the culture medium showed that a considerable amount of PGA2 was produced from PGE2. These observations suggest that PGE2 inhibits the cell growth of HT-29 without stimulation of cAMP production, and that this inhibitory effect was due to the metabolic change of PGE2 to PGA2.

Clinicopathological and Nuclear DNA Analyses of Gastric Leiomyomatous Tumors.

胃平滑筋原性腫瘍切除18例 (筋腫8例・肉腫10例) について, 臨床病理学的ならびにflow cytometry (FCM) によりDNAパターンを検討した.肉腫の腫瘍径10.3±2.2cmは筋腫の4.9±0.88cmより有意 (p<0.01) に大きく, 肉腫の原疾患による死亡症例では腫瘍径と生存期間との問に負の相関Y=23.3-0.35X (r=-0.907, p<0.01) が認められた, 肉腫の核分裂数 (核分裂数/400倍率の100視野) 49.3±23.3は筋腫の2.6±1.1よりも有意に (p<0.05) 多かった.肉腫6例と筋腫5例のパラフィン包埋切片を用いてのDNAの測定では, 筋腫全例と1例の肉腫はdiploidパターンを示し腫瘍死例はなかったが, 5例の肉腫はaneuploidパターン (平均DI=1.72) を示し, このうち再発ないし再燃で4例が死亡した.以上の成績より, 腫瘍径・核分裂数とFCMによるDNAパターン解析は筋原性腫瘍の良悪性の判定や治療方針の決定ならびに予後の予測に有用であると考えられる.