Masakazu Murakami

nm23-H1 reduces in vitro cell migration and the liver metastatic potential of colon cancer cells by regulating myosin light chain phosphorylation.

The nm23‐H1 gene is known as a potential metastasis suppressor gene in various types of carcinomas. However, the role of nm23‐H1 in colorectal carcinoma still remains controversial and the cellular mechanisms by which its protein may modulate the metastatic phenotype are not yet known. We transfected nm23‐H1 cDNA into the human colon cancer cell line, HT‐29, to test the effects and cellular biological mechanism of nm23 protein in colon cancer. We found that nm23‐H1 strongly inhibited the liver metastasis of HT‐29 cells in nude mice and inhibited the epidermal growth factor (EGF)‐induced cell migration in vitro. Furthermore, we clarified the regulation of the myosin light chain (MLC) phosphorylation by nm23‐H1, which has been demonstrated as having potential role in cell migration.

Aberrant promoter methylation in human DAB2 interactive protein ( hDAB2IP ) gene in gastrointestinal tumour

The human DOC-2/DAB2 interactive protein (hDAB2IP) gene is a novel member of the Ras GTPase-activating family and has been demonstrated to be a tumour-suppressor gene inactivated by methylation in several cancers. In this study, we analysed the methylation and expression status of hDAB2IP in gastrointestinal tumours. The promoter region of hDAB2IP was divided into two regions (m2a and m2b) based on our previous report, and the methylation status was determined by bisulphite DNA sequencing in gastric cancer cell lines. The gene expression was semiquantified by real-time RT–PCR, and the results indicated that the m2b promoter region might be an authentic methylation-mediated key regulator of the gene expression. Based on the sequence data, we developed a methylation-specific PCR (MSP) for the m2a and m2b regions and applied it to the samples. Methylation-specific PCR revealed aberrant methylation in the m2a region in eight of 12 gastric cancer cell lines (67%), 16 of 35 gastric cancer tissues (46%) and 29 of 60 colorectal cancer tissues (48%), and in the m2b region in eight of 12 cell lines (67%), 15 of 35 gastric cancer tissues (43%) and 28 of 60 colorectal cancer tissues (47%). On the other hand, seven (12%) and 11 (19%) of 59 gastrointestinal nonmalignant mucosal specimens showed methylation in the m2a and m2b regions, respectively, suggesting that hDAB2IP methylation might play a causative role in carcinogenesis. The 5-aza-2′-deoxycytidine treatment restored the gene expression in the m2b-methylated cell lines, confirming that the methylation caused gene downregulation. We also examined the relationship between hDAB2IP methylation and the clinicopathological features in patients with primary tumours, and determined that methylation in the m2b region was associated with location of the tumour in the stomach. In summary, our results demonstrated that hDAB2IP methylation is frequently present in gastrointestinal tumours and that the resulting gene silencing plays an important role in gastrointestinal carcinogenesis.

Antitumor effects and drug interactions of the proteasome inhibitor bortezomib (PS341) in gastric cancer cells

The proteasome inhibitor bortezomib (PS341) inhibits the function of the 26S proteasome and has been extensively investigated in the clinical setting of hematologic malignancies. Remarkable efficacy has been reported in the treatment of multiple myeloma, but there have been few studies of its use in the treatment of gastrointestinal malignancy, especially gastric cancer. Here, we demonstrate its efficacy, both alone and in combination with other cytotoxic agents, in gastric cancer cell lines. The human gastric cancer cell lines AZ521, MKN45 and NUGC3 were used as experimental models. Bortezomib produced significant growth inhibition in these cells (mean IC50 values: 1.26, 9.44 and 8.63 μmol/l, respectively) and was also observed to decrease the activity of the extracellular signal-regulated kinase 1/2 and Akt signal pathways, increasing the accumulation of p21. Cell-cycle analysis revealed that a low concentration of bortezomib (10–100 nmol/l) increased accumulation in the G1 phase. Moreover, bortezomib showed synergistic growth inhibition in combination with the conventional cytotoxic agents 5-fluorouracil, paclitaxel, doxorubicin and SN-38, and also downregulates the activity of nuclear factor -κB, which is induced by these agents. Our results demonstrate that bortezomib could be an effective antitumor agent in the treatment of gastric cancer, both as single-agent therapy and in combination with conventional chemotherapeutic agents.

Thymidine Phosphorylase and Dihydropyrimidine Dehydrogenase Expression Levels in Tumor and Normal Tissue Specimens of T3 Human Colorectal Carcinoma

PurposeThymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) are important enzymes related to the metabolism of 5-fluorouracil and its derivatives. We evaluated the association between the clinicopathological factors and these enzymes in patients with T3 colorectal carcinoma.MethodsThe TP and DPD expression levels in 15 patients with T3 colorectal carcinomas were measured in tumor and adjacent normal tissue specimens by enzyme-linked immunosorbent assay. Correlations between each enzyme and clinicopathological factors were also statistically evaluated.ResultsThe TP levels in tumor and normal tissue specimens were 77.9 ± 33.6 and 24.7 ± 10.3, respectively (P < 0.001). The DPD levels in tumor and normal tissue specimens were 44.1 ± 18.2 and 53.1 ± 24.1, respectively (P = 0.46). The TP/DPD ratios in tumor and normal tissue specimens were 1.84 ± 0.52 and 0.53 ± 0.26, respectively (P < 0.001). The tumor/normal ratios of TP level in patients with and without liver metastasis were 1.79 ± 0.91 and 4.67 ± 2.51, respectively (P = 0.024).ConclusionThe measurement of the enzyme expression levels of TP and DPD is considered to be useful for better understanding the conditions of tumor progression. The mechanisms of regulation of these enzymes thus require further evaluation.

Case of Adenocarcinoma with Gastric Diverticulum Arising in Barrett Esophagus.

Barrett食道に発生したと思われる食道腺癌で術前検査にて血清CEAの異常高値が認められた1症例を経験した.症例は60歳の男性で9年前からの巨大な胃憩室にて経過観察中であった.術前検査では下部食道に潰瘍形成を伴う腫瘤像を認め, 血清CEA値は44.7ng/mlと異常高値を示していた.切除標本にて本来の食道胃接合部位より9.3cm口側まで腸上皮化成を伴った円柱上皮の部分を, また同部に島状に扁平上皮の残存を認めた.腫瘍部は中分化腺癌の所見を呈しており, 深達度はa1, INFβであった.また噴門部のリンパ節にのみ転移を認めた.術後の血清CEA値は4日目に26.1ng/mlと速やかに減少したが, その後減少が遅延し, 精査を行ったところ, 手術より2か月後に左の肋骨への転移巣が発見された.血清CEA値の測定は経過観察に有用であった.

A trial of the intraperitoneal administration of recombinant interferon-.BETA. for the prevention of the postoperative peritoneal recurrence in gastric cancer with serosal invasion.

漿膜露出胃癌の腹膜再発防止の目的でRecombinant interferon-β (IFN-β) の術後腹腔内投与を試みた.胃癌癌性腹水10例では著効2例, 有効4例 (奏効率60%) を得た. 特に低分化腺癌, 印環細胞癌に強い効果を認めた. 発熱以外の重篤な副作用はなく, 剖検例の検索で癒着を促進するような刺激作用は認めなかった. 漿膜露出胃癌13例に対する術後腹腔内投与では, 縫合不全, イレウスなどの合併症は無く治癒手術例では腹膜再発を認めていない.S2, 肉眼的治癒手術例を対象にIFN-βの術後腹腔内投与の有無での比較試験を行っており, 術後補助療法としての本法の評価を明らかにしたいと考えている.