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T Yamori

Publications and source records attributed to T Yamori.

At least 37 records · Page 2Linked to original sources
PubMed1999

Constitutive activation of the 41-/43-kDa mitogen-activated protein kinase signaling pathway in human tumors.

The 41-kDa and 43-kDa mitogen-activated protein (MAP) kinases play a pivotal role in the mitogenic signal transduction pathway and are essential components of the MAP kinase cascade, which includes MAP kinase kinase (MEK) and Raf-1. As aberrant activation of signal transducing molecules such as Ras and Raf-1 has been linked with cancer, we examined whether constitutive activation of the 41-/43-kDa MAP kinases is associated with the neoplastic phenotype of 138 tumor cell lines and 102 primary tumors derived from various human organs. Constitutive activation of the MAP kinases was observed in 50 tumor cell lines (36.2%) in a rather tissue-specific manner: cell lines derived from pancreas, colon, lung, ovary and kidney showed especially high frequencies with a high degree of MAP kinase activation, while those derived from brain, esophagus, stomach, liver and of hematopoietic origin showed low frequencies with a limited degree of MAP kinase activation. We also detected constitutive activation of the 41-/43-kDa MAP kinases in a relatively large number of primary human tumors derived from kidney, colon and lung tissues but not from liver tissue. Many tumor cells, in which point mutations of ras genes were detected, showed constitutive activation of MAP kinases, however, there were also many exceptions to this observation. In contrast, the activation of the 41-/43-kDa MAP kinases was accompanied by the activation of Raf-1 in the majority of tumor cells and was completely associated with the activation of MEK and p90rsk in all the tumor cells examined. These results suggest that the constitutive activation of 41-/43-kDa MAP kinases in tumor cells is not due to the disorder of MAP kinases themselves, but is due to the disorder of Raf-1, Ras, or some other signaling molecules upstream of Ras.

Amino Acid Sequence↗
PubMed1999

Furanonaphthoquinone analogs possessing preferential antitumor activity compared to normal cells.

The 50% growth inhibition toxicity (IC50 at 72 h) of 16 synthetic and 2 phytochemical natural analogs of furanonaphthoquinones (naphtho[2,3-b]furan-4,9-dione; FNQ) and 2 analogs of isofuranonaphthoquinones was assayed in vitro in respect to established human cervical cancer and lung adenocarcinoma cells in comparison with human uterine endocervical, tracheal and bronchiolar epithelial cells and fibroblasts. Prostate, cholangio, colon, laryngeal, and tongue carcinoma cell lines and two osteosarcoma cell lines were also used for the assay. The IC50 ratio of normal cells to cancer cells was estimated in order to represent preferential antitumor activity. Two analogs, 2-methylnaphtho[2,3-b]furan-4, 9-dione (FNQ3) and 2-methyl-5(or 8)-hydroxynaphtho[2,3-b]furan-4, 9-dione (FNQ13) showed 10.4 to 14.1 IC50 ratios for all carcinoma cells used, indicating a wide spectrum. Among different carcinomas, there was no difference or variety in the IC50 ratio of a single analog. A moderate IC50 ratio (3.1-4.7) was also found in nine analogs, but seven others were equally cytotoxic (less than 2.6) to both cancer and normal cells. Two isofuranonaphthoquinone derivatives were ineffective, but a thieno derivative was equally cytotoxic to all cells tested. On the basis of the IC50 ratio data and the structure of the furanonaphthoquinones, the following structural activity (selectivity) relationship can be postulated: (i) the presence of an alkyl group at position 2 enhances the IC50 ratio, particularly the methyl group; (ii) a hydroxyl group at position 5 or 8 enhances the IC50 ratio; and (iii) methylation of the phenolic hydroxyl group leads to a decrease of potency. These results indicate that FNQ3, 13, and some other analogs are more preferentially cytotoxic to human tumor cells than to normal cells, unlike mitomycin-C, adriamycin, carboplatin, and methotrexate which are cytotoxic to the both. In nude mouse xenograft tests, FNQ3 demonstrated a significant antitumor activity with T/C% values of 16. 6 to 41.6 against several human carcinoma and osteosarcoma cells.

Animals↗
PubMed1998

Up-regulation of p27Kip1 correlates inversely with anchorage-independent growth of human cancer cell lines.

We examined the correlation between anchorage-independent growth and cell cycle-related molecules using 39 human cancer cell lines. They consisted of lung-, colon-, stomach-, breast-, ovarian-, brain-, renal- and melanoma-derived cell lines. Their anchorage-independent growth ability varied, but was not clearly related to the tissue of origin. There was a tendency for the levels of cyclin D1, cyclin E, cyclin A, p27, and p21 to show a tissue-dependent expression pattern. Statistical analysis revealed an inverse correlation of the p27 level with anchorage-independent growth (r=-0.456, P<0.01). Thus, the regulation of p27 is suggested to be linked to the anchorage independence of human cancer cells.

Cell Adhesion↗
PubMed1997

Isolation of murine and human homologues of the fission-yeast dis3+ gene encoding a mitotic-control protein and its overexpression in cancer cells with progressive phenotype.

To investigate genes involved in metastasis, we used a differential display method to compare the levels of gene expression in three cell lines derived from murine colon-adenocarcinoma 26 that show different metastatic potentials. The results, and subsequent Northern analyses, confirmed that one gene was expressed most strongly in NL17, the cell line with the highest experimentally metastatic potential to the lung; strongly in NL22, the line with moderately metastatic potential; and very weakly in NL4, which has no metastatic potential in recipient mice. Using this fragment as a probe, we isolated the murine cDNA as well as its human homologue and determined their DNA sequences. The cDNA sequences from both species contained open reading frames of 2874 nucleotides, encoding peptides of 958 amino acids with calculated molecular weights of approximately 109,000; the murine and human nucleotide sequences were 90% identical. The deduced amino acid sequences of these cDNAs revealed significant homology (45% identity) to the dis3+ gene product of Schizosaccharomyces pombe, a protein thought to be essential for mitotic control in the yeast. We therefore termed the murine and human genes hmc (homologue to the mitotic-control gene) and HMC, respectively. In 7 of 13 patients with colorectal cancers and liver metastases, expression of HMC was increased up to 38-fold in primary tumors and metastatic foci as compared to adjacent normal colorectal mucosa. An increase in expression of HMC, its novel product likely to belong to a structurally distinct family of mitotic-control proteins, may be associated with malignant phenotypes of some colorectal cancers.

Adenocarcinoma↗
PubMed1997

Anti-tumor efficacy of paclitaxel against human lung cancer xenografts.

We examined paclitaxel for anti-tumor activity against human lung cancer xenografts in nude mice and compared its efficacy with that of cisplatin, currently a key drug for lung cancer chemotherapy. Five non-small cell lung cancers (A549, NCI-H23, NCI-H226, NCI-H460 and NCI-H522) and 2 small cell lung cancers (DMS114 and DMS273) were chosen for this study, since these cell lines have been well characterized as regards in vitro and in vivo drug sensitivity. These cells were exposed to graded concentrations of paclitaxel (0.1 to 1000 nM) for 48 h. The 50% growth-inhibitory concentrations (GI50) for the cell lines ranged from 4 to 24 nM, which are much lower than the achievable peak plasma concentration of paclitaxel. In the in vivo study, 4 cell lines (A549, NCI-H23, NCI-H460, DMS-273) were grown as subcutaneous tumors xenografts in nude mice. Paclitaxel was given intravenously as consecutive daily injections for 5 days at the doses of 24 and 12 mg/kg/day. Against every xenograft, paclitaxel produced a statistically significant tumor growth inhibition compared to the saline control. Paclitaxel at 24 mg/kg/day was more effective than cisplatin at 3 mg/kg/day with the same dosing schedule as above, although the toxicity of paclitaxel was similar to or rather lower than that of cisplatin, in terms of body weight loss. In addition, paclitaxel showed potent activity against 2 other lung cancer xenografts (NCI-H226 and DMS114). Therefore, paclitaxel showed more effective, wider-spectrum anti-tumor activity than cisplatin in this panel of 6 lung cancer xenografts. These findings support the potential utility of paclitaxel in the treatment of human lung cancer.

Animals↗
PubMed1997

Isolation of a novel gene showing reduced expression in metastatic colorectal carcinoma cell lines and carcinomas.

To investigate genes involved in metastatic stages of cancer, we analyzed expression of mRNAs in three cell lines derived from murine colon adenocarcinoma 26 by means of a differential display method. Each of these lines exhibits distinct metastatic characteristics. Among many bands representing different expression patterns in the display, we confirmed by northern analysis that a gene corresponding to one amplified fragment, termed grm2 (gene related to metastasis 2), was expressed more abundantly in NL4, the derivative with the lowest metastatic potential, than in cell lines NL17, an experimentally metastatic derivative, and in NL22, a spontaneously metastatic derivative. Using the grm2 fragment as a probe, we isolated murine cDNA clones and subsequently human cDNA clones corresponding to the GRM2 gene. The human and mouse homologues both encode proteins of 600 amino-acid residues, which show weak homologies to proteins belonging to the myosin family. When we examined the expression levels of this novel gene in human colon cancers and in corresponding metastatic foci, we found that in more than half of these tissues, expression was significantly reduced in association with malignant potential. Our results imply that in humans the GRM2 gene product may regulate the metastatic phenotype of some colorectal cancers.

Adenocarcinoma↗
PubMed1997

[A human cell line panel for screening anti-cancer drugs].

Development of more useful screening systems for anti cancer drugs is important to accelerate efficiency of finding new leads. The National Cancer Institute (NCI) has recently developed a unique screening methodology using a human cell line panel. We have established a new human cell line panel according to this news methodology, and studied its feasibility. Concentration of a certain sample to inhibit proliferation of tumor cells of the panel varies and gives a characteristic pattern called a "finger print". Analysis of finger prints of more than 100 compounds, including currently used anti cancer drugs, revealed that finger prints appeared to be similar among drugs with the same mode of action. One can predict the mode of action of sample compounds by applying the above feature to the analysis of samples, which is the most variable advantage of this method. Then, one may select promising compounds by considering their effective concentrations and finger prints. Secondary screening by a panel of nude mice xenografts that correspond to cultured cell lines will follow the above screening. We consider that the in vitro and in vivo screening by a human cell line panel is a new and useful system for evaluation of anti cancer drugs.

Animals↗
PubMed1996

Expression of carbohydrate-binding protein p33/41 in human tumor cell lines.

We previously reported a new type of lectin, p33/41 (annexin IV), which was isolated from a bovine tissue extract [Kojima, K. et al. (1992) J. Biol. Chem. 267, 20536-20539]. When the expression of p33/41 (annexin IV) was surveyed in the lysates of 39 human tumor cell lines by SDS-PAGE, followed by Western blot analysis with polyclonal anti-bovine p33/41 and monoclonal anti-annexin IV (Z016, Zymed) antibodies, 21 cell lines were found to be reactive with the polyclonal antibody, whereas all 39 cell lines were stained with Z016. These results together with those obtained with standard proteins, annexins IV and V, suggested that the monoclonal antibody, Z016, recognizes annexin V, but not p33/41 (annexin IV). Therefore, we performed cDNA cloning of human p33/41 (annexin IV) to prepare a recombinant protein and raised monoclonal antibodies against the protein. Northern blot analysis with the cDNA as a probe showed that a human colon cancer cell line, HT29, contains p33/41 (annexin IV) mRNA of two sizes, 2.0 and 3.0 kb. The two monoclonal antibodies, AS11 and AS17, against the recombinant protein generated were useful for flow cytometric analysis, ELISA, Western blot analysis and immunoprecipitation. Flow cytometric analysis with AS17 showed that p33/41 (annexin IV) is located in the cytoplasm of HT29 cells, but not on the cell surface. However, one of the cell surface proteins first labeled with biotin and then solubilized with a detergent was immunoprecipitated with AS17. The results suggest the existence of a membrane spanning form of p33/41 (annexin IV).

Adenocarcinoma↗
PubMed1996

Identification of interleukin-6 as a factor that induces neurite outgrowth by PC12 cells primed with NGF.

We have screened for a factor that induces neurite outgrowth by PC12 cells only after NGF pretreatment in the supernatants of 38 transformed cell lines, finding three positive clones. The factor showing the strongest activity was purified and identified as IL6. In this NGF-IL6 system, the process of neurite outgrowth by PC12 cells can be separated into NGF-dependent and IL6-dependent steps. The IL6-dependent step requires RNA synthesis, suggesting that IL6 induces new gene expression depending on NGF-priming. These findings suggest that the gene expression during the differentiation process is regulated by at least two signals.

Animals↗
PubMed1996

Establishment of a hepatocyte cell line producing growth-promoting factors for liver-colonizing tumor cells.

A hepatocyte-derived cell line designated MLE-15A2 was established from a primary culture of mouse hepatocytes. The MLE-15A2 cells appeared to retain the basic nature of hepatocytes in that they showed morphology of an epithelial cell type and secreted albumin into the culture medium. These cells were grown on collagen-coated plates and could be easily expanded to a large-scale culture. Therefore, MLE-15A2 cells may provide a more useful model for studying liver microenvironments than primary cultures of hepatocytes. We found that conditioned media from MLE-15A2 cells, as well as from primary cultures of hepatocytes, promoted the proliferation of highly liver-colonizing colon 26 NL-17 cells better than the poorly liver-colonizing colon 26 NL-4 cells. Moreover, the conditioned media stimulated the growth of some human colon cancer cell lines. These results indicate that MLE-15A2 cells secrete growth factors that selectively stimulate certain tumor cell types. Hepatocyte-derived growth factors may regulate selective survival and colonization of tumor cells in the process of liver metastasis. The growth-promoting activity was unaffected by dialysis, was stable at 80 degrees C for 30 minutes and was bound to a heparin-Sepharose column. The major activity was eluted from the column with 0.7-0.75 M NaCl, and some minor activities eluted with lower concentrations of NaCl. These results suggest that the active components are heterogeneous heparin-binding proteins with lower affinity to heparin than platelet-derived and fibroblast growth factors.

Animals↗
PubMed1996

A novel differentiation factor for PC12 cells from culture supernatant of mouse hepatocyte cell line MLE-15A2.

We have found a factor that induces neurite outgrowth of rat PC12 cells in the culture supernatant of the cell line MLE-15A2. This factor was designated as MDDF. The factor was sensitive to protease, dithiothreitol, and high-temperature treatments. The apparent molecular mass was 80 kDa on Superdex 200 gel filtration. No significant tyrosine phosphorylation was detected after MDDF stimulation in Western blotting analysis with anti-phosphotyrosine antibody, suggesting that the signal transduction may not be mediated by a tyrosine kinase cascade that is involved in signaling of most of the known factors. Activation of MAP kinase was very weak and was seen only 5 min after stimulation, suggesting that prolonged activation of MAP kinase was not required for neurite outgrowth induced by MDDF. Because the biochemical characteristics of MDDF are different from those of any known peptide factors that induce neurite outgrowth of PC12 cells, MDDF may be a novel differentiation factor for PC12 cells.

Animals↗
PubMed1995

Purification and characterization of the platelet-aggregating sialoglycoprotein gp44 expressed by highly metastatic variant cells of mouse colon adenocarcinoma 26.

A platelet-aggregating sialoglycoprotein with a molecular weight of 44,000 (gp44) was immunochemically purified from highly metastatic mouse adenocarcinoma cells. The rat monoclonal antibody (mAb) 8F11 used in the purification procedure has been generated previously against NL-17 cells derived from the mouse colon 26 cell line, mAb 8F11 inhibits NL-17 cells from inducing platelet aggregation and suppresses their experimental metastasis to the lung. The purified gp44 induced mouse platelet aggregation in a dose-dependent manner without any plasma component. This aggregation was completely inhibited by mAb 8F11. The gp44 was partially characterized by sequential enzymatic hydrolysis of carbohydrates and was found to be O-glycans enriched. When gp44 was sequentially treated with N-glycanase and neuraminidase, it lost platelet aggregation activity. Further treatment with O-glycanase resulted in a loss of the reactivity to mAb 8F11. These results suggest that sialylated carbohydrate chains of gp44 are involved in the induction of platelet aggregation and may play an important role in the colonization of NL-17 cells in the lung.

Adenocarcinoma↗
PubMed1995

Production of monoclonal antibodies specific to the carboxyl terminal region of the 85 kDa subunit of phosphatidylinositol 3-kinase: use of the antibodies in recognition of mutant p85.

We have established two hybridomas producing mAb to the carboxyl terminal region of phosphatidylinositol-3 kinase 85 kDa subunit type alpha (p85 alpha). Analysis using deletion mutants of p85 revealed that epitopes for the two mAb were located on the border of the src homology 2 (SH2) sequence located at the carboxyl end of p85. They immunoprecipitated free p85 efficiently, but reactivity to p85 bound to p110 was very weak. Together with the mAb which we have reported previously, a panel of mAb that covered the various parts of p85 alpha was obtained. Using this panel, we characterized two mutants of p85 (70 and 50 kDa) expressed in the human colon carcinoma cell line, HCC2998. No wild-type p85 was detected in these cells. A mAb specific to the carboxyl terminal region detected p70 but not p50, suggesting that this region is missing in p50. The panel of mAb is a useful tool to use to analyse mutant forms of p85.

Animals↗
PubMed1995

Expression of sulfomucins in normal mucosae, colorectal adenocarcinomas, and metastases.

We have examined the expression of specific mucin antigens in tissue sections from 92 cases of colorectal carcinoma, using sulfomucin-specific monoclonal antibody (MAb) 91.9H. The expression of sulfomucins was high in normal mucosae and much lower in primary colorectal carcinoma, in metastatic lesions in lymph nodes or in liver. The intracellular localization of sulfomucins was also different among these tissues. In normal mucosae, MAb 91.9H binding was seen in the supranuclear area, presumably Golgi complexes, the luminal surface, and secretory products. In primary colorectal carcinomas and in their metastatic lesions, MAb 91.9H was preferentially localized in the cell surface and substances attached to the luminal surface of glandular structures. Analysis of the lysates of normal and tumor tissues showed that very-high-molecular-weight components contained the antigenic epitopes. The intensity of MAb 91.9H binding was lower in tumors at advanced stages than in tumors at early stages. These high-molecular-weight components were apparently reactive with MAb FH6 specific for sialyl-Le(X) (s-Le(X) structures. Histological specimens with low levels of MAb 91.9H reactivity often exhibited relatively high levels of MAb FH6 reactivity. These two mucins may have reversed expression during carcinogenesis and carcinoma progression, and this change may be related to metastatic potential.

Adenocarcinoma↗
PubMed1995

Effects of growth hormone and insulin-like growth factor I on testosterone secretion in premature male rats.

Present study was planned to clarify the effects of GH and insulin-like growth factor I (IGF-I) on testosterone secretion using premature male rats. Forty rats were divided four groups. GH, IGF-I, both of them or normal saline solution as control were subcutaneously administered to the rats of each group for seven days from 3-week to 4-week of age. After the treatment, six of each group were used to human chorionic gonadotropin (hCG) loading and four to Leydig cell preparation. Serum testosterone responses to hCG loading were significantly higher in 4-week-old rats treated with GH and/or IGF-I for 1 week than in control rats. However, the responses were similar among three treated groups (GH, IGF-I and both). After one-week treatment with GH and/or IGF-I, isolated Leydig cells were prepared from testes of 4-week-old rats and testosterone production by the stimulation of hCG was examined. Amounts of testosterone production stimulated by hCG were significantly greater in the treated rats than in control rats. These findings suggest that GH mediated by IGF-I promotes the testicular responsiveness to gonadotropin on testosterone production in premature rats.

Analysis of Variance↗
PubMed1995

[Combination therapy of doxifluridine, pirarubicin and cisplatin for human gastric cancers implanted in nude mice].

In the preclinical study of a new combination therapy for gastric cancer, dFTP, consisting of doxifluridine (5'-DFUR), pirarubicin (THP) and cisplatin (DDP) as a modification of conventional FAP regimen (5-fluorouracil+Adriamycin+DDP), we compared antitumor and toxic effects of two sequential treatment schedules, single injection of DDP before or after 4 daily administrations of 5'-DFUR, on 5 strains of human gastric cancer bearing nude mice. Results indicated that both schedules of the dFTP regimen had potent antitumor effects. There was no significant difference between them. On the other hand, in terms of the host toxicity as observed by body weight loss, the post-DDP schedule was significantly less toxic than pre-DDP. These results suggest that dFTP regimen (post-DDP schedule) may be useful for clinical treatment of gastric cancers.

Adenocarcinoma↗
PubMed1994

Expression of insulin receptor substrate-1 in hepatocytes: an investigation using monoclonal antibodies.

To investigate the expression and subcellular distribution of insulin receptor substrate-1 in hepatocytes, which are major targets of insulin along with muscle and adipose tissue, we obtained monoclonal antibodies by immunizing mice with a fusion protein consisting of the C-terminal portion of the human insulin receptor substrate-1 and glutathione-S-transferase. Two of the monoclonal antibodies (designated as 7B3 and 6G5) were found to be useful for immunohistochemical studies. Using 6G5 we demonstrate a high level of expression of insulin receptor substrate-1 in liver cirrhosis hepatocytes and variable expression in hepatocellular carcinoma cells. These results suggest that insulin receptor substrate-1 may play a role in liver regeneration during cirrhosis and that an insulin signaling cascade may be involved in hepatocarcinogenesis.

Animals↗