Analysis of the β-Catenin/T Cell Factor Signaling Pathway in 36 Gastrointestinal and Liver Cancer Cells

We investigated the frequency and mechanism of |bT-catenin/T cell factor (Tcf) signaling activation in a panel of 36 human gastrointestinal and liver cancer cell lines. Reporter assay and electrophoretic mobility shift assay revealed that the β-catenin/Tcf signaling was upregulated in 12 of 12 (100%) colorectal, 5 of 8 (68%) gastric, 2 of 7 (29%) hepatic, and none of 9 pancreatic cancer cell lines. The activation of the pathway was mainly due to the mutation of adenomatous polyposis coli (APC) or β-catenin, and Tcf-4 was highly expressed in these cell lines with upregulated signaling. Nuclear β-catenin was observed not only in the signaling-activated cell lines, but also in 14 of 25 (56%) primary gastric cancers, 15 of 20 (75%) colon cancers, 5 of 19 (26%) hepatocellular carcinomas, and none of 13 pancreatic cancers. The presence of signaling-upregulated gastric cancer cell lines with intact APC and β-catenin suggests the involvement of other mechanisms than mutations of APC or β-catenin.     

Significant growth inhibition of human lung cancer cells both in vitro and in vivo by the combined use of a selective cyclooxygenase 2 inhibitor, JTE-522, and conventional anticancer agents.

This study reports that a selective COX-2 inhibitor JTE-522inhibits both in vitro and in vivo growth of human lung cancer cells as a single agent. Furthermore, the adjunct use of JTE-522 is shown to significantly enhance treatment efficacy of conventional anticancer drugs not only in vitro but also in vivo without causing any noticeable side effects. Indeed, IC(50)s of various anticancer agents in vitro were reduced by up to 70%, whereas the combination therapy of JTE-522 with docetaxel and vinorelbine inhibited tumor growth in vivo by 65 and 55%, respectively. Taken together, these findings suggest that the use of a selective COX-2 inhibitor in the treatment of lung cancer may be promising, especially because of its enhancement of the treatment efficacy of conventional anticancer agents without compromising quality of life.     

Transgenic Rats Carrying Human c-Ha-ras Proto-oncogene Are Highly Susceptible to N-Nitrosomethylbenzylamine Induction of Esophageal Tumorigenesis

A transgenic rat line carrying three copies of the human c‐Ha‐ras proto‐oncogene, including its own promoter region, has been established in our laboratory (Hras128 rats), and shown to be highly susceptible to induction of mammary and urinary bladder tumors. Mutation analysis of induced lesions indicated the majority to contain some but not all cells with transgene mutation. In the present study, the susceptibility of Hras128 rats to N‐nitrosomethylbenzylamine (NMBA) induction of esophageal tumors was examined with a similar mutation analysis of the transgenes. Male 6‐week‐old Hras128 and wild littermate rats were treated with NMBA, 0.5 mg/kg subcutaneously, 3 tunes a week for 5 weeks and then maintained for 5 weeks without any further treatment. Multiple esophageal tumors, squamous cell pappillomas and carcinomas, rapidly developed within this 10–week experimental period in Hras128 rats (11.05+7.83/rat). In contrast, wild‐type litter‐mates had only small numbers of mostly benign tumors (1.67+2.06/rat). The Hras128 rats had no other tumors or abnormalities. In their esophageal lesions, codon 12 GGC to GAC mutations of the transgene were frequently detected by restriction fragment length polymorphisms (RFLP) and subsequent direct sequencing analysis (19/25, 76%). In the endogenous rat c‐Ha‐ras gene they were less frequent (2/25, 8%), than in wild‐type rats (8/14, 57.1%). The densities of mutated bands in the RFLP analysis indicated that mutated cells were major populations in tumors, in contrast to the case with mammary and urinary bladder lesions. Furthermore, activated ras protein, detected by binding to raf protein, was clearly increased in tumors as compared to surrounding epithelium or the normal esophagus of untreated rats. The results show that Hras128 rats are highly susceptible to NMBA esophageal carcinogenesis, as well as induction of mammary and urinary bladder tumors, but that tissue‐specific characteristics exist for the roles of transgene ras mutations.     

Complications of percutaneously inserted central venous catheters in Japanese neonates

Background: To determine institutional policies concerning percutaneously inserted central venous catheter (PICC) utilization and also frequencies of complications such as pericardial effusion (PCE), cardiac tamponade (CT), pleural effusion, ascites, venous thrombosis, and catheter removal difficulties. Methods: Nationwide postal questionnaire survey was carried out that included institutional policies on PICC and numbers of complications recorded from January 1999 to December 2003. Results: A total of 98 replies were received from 193 neonatal intensive care units (NICU) in Japan. As a catheter tip location, positions outside of the heart were highly preferred, while only 9% accepted a right atrial position. Twenty‐eight cases of PCE or CT were reported, representing an estimated frequency of 0.07–0.11% of PICC insertions. Pleural effusion/ascites and removal difficulties (36 and 35 cases, respectively) were encountered in approximately 0.09–0.14% of insertions. Conclusions: Frequency of PCE/CT appeared comparable to previously reported occurrences. Also, pleural effusion/ascites and removal difficulty appeared to be rare complications.     

Triazine Derivatives Inhibit Rat Hepatocarcinogenesis but Do Not Enhance Gap Junctional Intercellular Communication

We report here novel candidate chemopreventive agents active against experimental hepatocarcino-genesis. The triazine derivatives 6-(2-chlorophenyl)-2,4-diamino-l,3,5-triazine (2CPDAT), 6-(3-chlorophenyl)-2,4-diamino-l,3,5-triazine (3CPDAT), 6-(4-chlorophenyl)-2,4-diamino-l,3,5-triazine (4CPDAT), 6-(4-pyridyl)-2,4-diamino-l,3,5-triazine (PyDAT), and 6-(pyridine JV-oxid-4-yl)-2,4-diamino-l,3,5-triazine (PyNODAT), synthesized in our laboratory, in addition to 6-(2,5-dichloro-phenyl)-2,4-diamino-l,3,5-triazme (DCPDAT), or irsogladine, which is a widely used anti-ulcer drug, were investigated for potential chemopreventive effects in a rat liver medium-term bioassay system. A significant inhibitory influence on enzyme-altered liver foci was found for 2CPDAT, 3CPDAT, 4CPDAT, and PyNODAT, but not for DCPDAT or PyDAT, The involvement of gap jnnctional intercellular communication in the inhibition was studied, but no change in gap Junctional intercellular communication capacity in rat liver cells in vitro or in gap junction protein (connexin 32) expression in rat liver in vivo was noted. These results indicate that, although these irsogladine analogues exert inhibitory effects on rat liver carcinogenesis, their action is independent of modification of gap Junctional intercellular communication.     

Differential Dose-dependent Effects of α-, β-Carotenes and Lycopene on Gap-junctional Intercellular Communication in Rat Liver in vivo

In order to examine the relevance of alteration of gap-junctional intercellular communication (GJIC) to chemopreventive activity against carcinogenesis, the effects of α and β -carotene as well as lycopene, typical chemopreventive carotenoids, on cell coupling via gap junctions in rat liver in vivo were studied using a direct functional dye-transfer technique. We found that all three test compounds given at a dose of 50 mg/kg-body weight (b.w.) daily, 5 times by gavage, inhibited GJIC, while similar treatment with 5 mg/kg b.w. caused enhancement, especially in the β-carotene and lycopene-treated groups. At the dose level of 0.5 mg/kg b.w., the three compounds had no effect. The findings show that all three agents differentially modulate GJIC depending on the dose, with beneficial effects on cell communication only detected at the one dose. The result suggests that determination of the dose of chemicals to be used is crucial for human intervention studies.     

Enhanced Tumor Localization of Radiolabeled Fab Fragments of Monoclonal Antibody A7 in Nude Mice Bearing Human Pancreatic Carcinoma Xenografts

Much recent research has been directed toward the use of monoclonal antibodies (MAb) for the inimunodetection of solid tumors. In pancreatic cancer, the results of conventional immunoscintigraphy using intact MAb remain disappointing. Clear immunoseintigrapliy with radiolabeled MAb requires a high tumor tissue/blood ratio of radioactivity and a low normal tissue/blood ratio of radioactivity. In this study, ¹²⁵I-labeled Fab fragments produced by papain digestion of MAb A7 were injected intravenously into nude mice bearing a human pancreatic cancer (HPC-YS) xenograft previously shown to react specifically with MAb A7. The radioactivity of tumors and normal organs was subsequently measured. The tumor tissue/blood ratio of ¹²⁵I-labeled Fab fragments of MAb A7 was 1.00±0.24 and 9.68±2.54 at 2 and 24 h after injection, respectively. The tumor tissue/blood ratio of radioactivity was significantly higher than those of normal organs at 24 h after injection. Moreover, the tumor tissue/blood ratio of ¹²⁵I-labeled Fab fragments of MAb A7 was greater than that of intact MAb A7, although the ¹²⁵I-labeled Fab accumulation level was much less than that of ¹²⁵I-labeled intact MAb A7 in the tumor. When mice bearing tumors which did not react with MAb A7 were studied, ¹²⁵I-labeled Fab fragments did not specifically localize to the tumors. These results suggest that Fab fragments of MAb A7 may be suitable carriers of radionuclides for the immunodetection of human pancreatic cancer.