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T Tsuruo

Publications and source records attributed to T Tsuruo.

At least 19 recordsLinked to original sources
PubMed1996

Potentiation of the reversal activity of SDZ PSC833 on multi-drug resistance by an anti-P-glycoprotein monoclonal antibody MRK-16.

SDZ PSC833 (PSC833), an analogue of cyclosporines, is one of the most potent modulators of multi-drug resistance (MDR). We previously reported that MRK-16, an anti-P-glycoprotein MAb, enhanced MDR reversal activity of cyclosporin A (CsA) through inhibition of P-glycoprotein-mediated CsA transport. We have examined here whether MRK-16 can enhance MDR reversal activity of PSC833. We found that MRK-16 potentiated the MDR reversal activity of PSC833, and of CsA, in MDR sublines of human myelocytic leukemia K562 and human ovarian cancer A2780 cells. Like MRK-16 combined with CsA, MRK-16 enhanced the effect of a sub-optimum dose of PSC833 on vincristine accumulation in MDR cells. However, MRK-16 could not increase cellular accumulation of PSC833 in MDR tumor cells, yet it could increase cellular accumulation of CsA. P-glycoprotein could not transport PSC833 but could transport CsA. Our results indicate that MRK-16 potentiates the MDR reversal activity of both PSC833 and CsA, yet also suggest that the molecular mechanism of the potentiation differs between the two substances.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Novel metastasis model of human lung cancer in SCID mice depleted of NK cells.

Metastasis is a critical problem in the treatment of human lung cancer. Thus, a suitable animal model of metastasis of human lung cancer is required for in vivo biological and preclinical studies. In this study, we tried to establish a suitable model for this, using SCID mice. Neither human SCLC H69/VP cells (5 x 10(6)) nor squamous-cell carcinoma RERF-LC-AI cells (1 x 10(6)), injected through a tail vein, formed metastases in untreated SCID mice. Pre-treatment of SCID mice with anti-asialo GM1 serum resulted in only a few metastases of H69/VP cells, but pre-treatment with anti-mouse IL-2 receptor beta chain Ab (TM-beta 1) resulted in numerous lymph-node metastases 56 days after tumor inoculation. H69/VP-M cells, an in vivo-selected variant line, formed significant numbers of lymph-node metastases even in SCID mice pre-treated with anti-asialo GM1 serum. SCID mice depleted of NK cells by treatment with TM-beta 1 showed different patterns of metastasis when inoculated intravenously with the 2 different human lung cancer cell lines (H69/VP and RERF-LC-AI cells): H69/VP cells formed metastases mainly in systemic lymph nodes and the liver, whereas RERF-LC-AI cells formed metastases mainly in the liver and kidneys, with only a few in lymph nodes. A histopathological study showed that the metastatic colonies consisted of cancer cells. The numbers of metastatic colonies formed by the 2 cell lines increased with the number of cells inoculated. TM-beta 1 treatment of SCID mice efficiently removed NK cells from peripheral blood for at least 6 weeks, whereas, after treatment of the mice with anti-asialo GM1 serum, NK cells were recovered within 9 days. These findings suggest that NK-cell-depleted SCID mice may be useful as a model in biological and pre-clinical studies on metastasis of human lung cancer.

Animals↗
PubMed1996

Brain capillary endothelial cells express two forms of erythropoietin receptor mRNA.

To study the existence of the erythropoietin receptor (Epo-R) mRNA in brain capillary endothelial cells, the reverse transcription (RT) PCR was performed using total RNAs from rat brain capillary endothelial cells (RBECs) and MBEC4, which is one of the established mouse brain capillary endothelial cell lines. Southern analysis of the RT-PCR products indicated that both RBECs and MBEC4 expressed an authentic form of Epo-R mRNA as a minor form and an intron-5-inserted form of Epo-R mRNA, thus a soluble form of Epo-R mRNA, as a major form. Furthermore, the effect of recombinant human erythropoietin (rHuEpo) on the DNA synthesis in RBECs was analyzed. rHuEpo showed a dose-dependent mitogenic action on RBECs as a competence factor. Radioiodinated rHuEpo was bound specifically to RBECs with time, cell number and dose dependencies. Binding studies with 125I-rHuEpo showed that RBECs had a single class of receptors with low-affinity (Kd = 860 pM) and that the number of sites/cell (10300) was abundant. These results suggest that brain capillary endothelial cells express not only an authentic form of Epo-R but also a soluble form of Epo-R and that erythropoietin acts directly on brain capillary endothelial cells as a competence factor.

Animals↗
PubMed1996

Chromosome 22 complements apoptosis in Fas-and TNF-resistant mutant UK110 cells.

Fas and p55 tumor necrosis factor receptor (TNFR) transfer an apoptosis signal when they are crosstinked with their ligands or agonistic antibodies. However, the signal transduction mechanism of apoptosis via Fas and p55 TNFR has not yet been elucidated. We previously described a recessive mutant UK110 from the human monocytic leukemia U937 cell line, that showed resistance against Fas- and p55 TNFR-mediated apoptosis. By cytogenetic analysis and microcell-fusion method, we demonstrate here that introduction of chromosome 22 can specifically restore the sensitivity to Fas- and TNF-mediated apoptosis in UK110 cells. Moreover, introduction of chromosome 22 into UK110 can complement the processing of interleukin-1 beta converting enzyme (ICE)-like proteases, such as CPP32/Yama/Apopain and ICH-1L, after treatment with anti-Fas and anti-p55 TNFR antibodies. These results suggest that the product of a gene located on chromosome 22 participates in the Fas-and p55 TNFR-mediated apoptosis at a point upstream of ICE-like proteases.

Amino Acid Sequence↗
PubMed1996

Antitumor activity of a novel podophyllotoxin derivative (TOP-53) against lung cancer and lung metastatic cancer.

We synthesized a potent new antitumor podophyllotoxin derivative (4beta-aminoalkyl-4'-O-demethyl-4-desoxypodophyllotoxin; TOP-53) in our search for a drug that has strong activity against lung cancer and lung metastatic cancer. TOP-53 exhibited twice the inhibitory activity of etoposide (VP-16) against topoisomerase II and induced DNA strand breaks but showed no inhibitory activity against tubulin polymerization. The in vitro cytotoxic activity of TOP-53 assessed as IC50 was 0.016-0.37 microg/ml and 0.26-8.9 microg/ml against marine tumor and human non-small cell lung cancer (NSCLC) cell lines, respectively. TOP-53 exerted significant efficacy equivalent to that of VP-16 on s.c.-implanted murine solid tumors (Colon 26, B16-BL6, and Lewis lung carcinoma) at doses 3-5 times lower than that of VP-16. In human tumor xenografts using NSCLC, TOP-53 was active for four of five tumors, whereas VP-16 was active for two of five tumors. Potent inhibitory activity of TOP-53 was also found against a lung tumor (Lewis lung carcinoma) and four lung metastatic tumors (NL-22 and NL-17 colon cancer, UV2237M fibrosarcoma, and K1735M2 melanoma). TOP-53 appeared to be more active against four of them than VP-16. Thus, TOP-53 is not only active against s.c.-implanted lung cancers but also strongly active against lung localized tumor and metastatic tumors in the lungs. The high selectivity of TOP-53 was attributed to its high distribution into the lung and its persistence. TOP-53 is expected to be highly effective against lung cancer including NSCLC and various lung metastatic tumors in the clinical field.

Animals↗
PubMed1996

DT-diaphorase as a critical determinant of sensitivity to mitomycin C in human colon and gastric carcinoma cell lines.

Mitomycin C (MMC), a known cytotoxic agent, requires cellular enzyme-mediated activation for effective antitumor activity. To study the bioreductive enzymes responsible for MMC activation in tumor cells, we examined the enzyme activities of DT-diaphorase (DTD) and NADPH:cytochrome P-450 reductase in 13 colon and gastric carcinoma cell lines and then compared these activities to the respective cellular MMC sensitivity. We found that cell lines with nonexistent or marginal DTD activity, such as St-4 and MKN7, showed resistance to MMC, in comparison to cell lines with DTD activity ranging from 210 to 1420 nmol/min/mg protein. No correlation was found between NADPH:cytochrome P-450 reductase activity and MMC sensitivity in these cell lines. To confirm the role of DTD in cellular MMC sensitivity, we constructed an expression vector containing NQO1, a gene that codes for DTD, and transfected the vector into St-4 cells expressing no DTD activity. Several transfectant clones with DTD activity from 144 to 2085 nmol/min/mg protein were obtained. All of the transfectants showed 5-10-fold higher sensitivity to MMC compared to the parental St-4 cells. Consistent with the MMC sensitivity, we also found that MMC-DNA adduct was formed more extensively in the NQO1 transfectants than in the St-4 cells. These results indicate that DTD activity is required for effective cytotoxicity of MMC in colon and gastric carcinoma cells.

Antibiotics, Antineoplastic↗
PubMed1996

A novel anti-Thy-1 (CD90) monoclonal antibody induces apoptosis in mouse malignant T-lymphoma cells in spite of inducing bcl-2 expression.

Mouse malignant T-lymphoma CS-21 cells can survive and proliferate in vitro when co-cultured with CA-12 stromal cells isolated from lymph nodes, but CS-21 cells undergo apoptotic cell death with DNA fragmentation when cultured alone. We immunized rats with CS-21 cells and raised monoclonal antibodies (MAbs) that recognized Thy-1 (CD90) or CD45 protein. The majority of these MAbs were able to inhibit the adhesion and apoptosis of CS-21 cells. When anti-Thy-1 MAbs were examined for their recognition site on Thy-1 glycoprotein, one of them, MCS-34, was found to recognize both Thy-1.1 and Thy-1.2. In addition, MCS-34, just like the anti-Thy-1 MAb G7, recognized the Thy-1A epitope. G7 was known to induce apoptosis in some T-cell hybridomas and in thymocytes. In CS-21 cells, however, G7 could not induce apoptosis, but MCS-34 could. Interestingly, MCS-34 enhanced the expression of bcl-2 protein, in spite of its ability to induce apoptosis. Upon examining the apoptosis-inducing mechanisms of MCS-34, we found that it promoted a sustained increase in cytoplasmic-free calcium in CS-21 cells. Calcium ionophore A23187 was also found to induce apoptosis in a dose-dependent manner. These results indicate that a sustained increase in cytoplasmic-free calcium by MCS-34 induces apoptosis in CS-21 cells in spite of bcl-2 protein expression.

Animals↗
PubMed1996

Measurement of P-glycoprotein expression in multidrug-resistant human neuroblastoma cell lines using self-competitive binding assay.

To date, all reported measurements of multidrug resistance have been semiquantitative. The purpose of the present study is to establish and validate the self-competitive binding assay technique utilizing monoclonal antibody for quantitative estimation of multidrug resistance in tumor cells. This technique is used for P-glycoprotein concentration measurement in BE(2)-C human neuroblastoma cell line and its sublines with primary resistance to colchicine and actinomycin D. Monoclonal antibody MRK-16 was used in this study. It was labeled with iodine-125 (125I) to trace the concentration of antibody-antigen complexes. The binding data were obtained by varying the concentration of the unlabeled antibody. The results were fitted to a model equation to estimate the number of binding sites and antibody-antigen dissociation constant. The P-glycoprotein concentration was significantly higher in the resistant sublines than in the sensitive line. The highest levels were achieved in actinomycin D-resistant cells: 2.1 x 10(6) binding sites/cell versus 5.4 x 10(4) binding sites/cell in the sensitive cells. The consistency of the results was verified by repeating the study three times for each cell line. The binding assay results were confirmed by Western blot experiments performed on the same cell lines.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Sensitivity of multidrug-resistant tumor cell lines to immunologic effector cells.

The ability of malignant cells to survive exposure to cytotoxic agents is a major obstacle to cure in patients with cancer. Multidrug resistance and the expression of P-glycoprotein are emerging as a cause of chemotherapy failure. Immunologic effector cells such as lymphokine-activated killer (LAK) cells or cytokine-induced killer (CIK) cells are capable of killing a broad range of tumor cell lines or freshly isolated tumor cells. As demonstrated here, LAK, and CIK cells possess a high level of cytotoxic activity against tumor cell lines both resistant and sensitive to chemotherapeutic agents such as doxorubicin or vinblastine. CIK cells possessed a higher level of cytotoxic activity than LAK cells as determined by 51Cr release and a tumor colony assay. Monoclonal antibodies against P-glycoprotein did not block the lysis of tumor cells resistant to chemotherapy by CIK cells. In contrast, antibodies to LFA-1 and ICAM-1 blocked CIK cell-mediated tumor cell lysis. These data demonstrate that immunological approaches to cancer therapy may be useful in overcoming disease caused by drug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Identification of genes differentially expressed in B16 murine melanoma sublines with different metastatic potentials.

B16-F10 and B16-BL6 are B16 mouse melanoma sublines that preferentially metastasize to the lung following i.v. and s.c. injections, respectively. To study molecular mechanisms underlying the different metastatic behaviors exhibited by the B16 melanoma sublines, we performed differential hybridization of the genes transcribed in these cells and compared their expression levels. We isolated four genes that were highly expressed in B16-F10 cells but not in B16-BL6 cells: TI-225 (polyubiquitin), TI-229 (pyruvate kinase), TI-241 (LRF-1 homologue), and TI-227 (novel gene). Triosephosphate isomerase, 10-formyltetrahydrofolate dehydrogenase, tyrosinase-related protein 2, cytochrome c oxidase, ATP synthetase alpha subunit, RNA helicase, and ribosomal protein (L37, J1, acidic phosphoprotein), however, showed higher expression in B16-BL6 cells than in B16-F10 cells. Among these clones, transfection of TI-241 into the low metastatic clone F1 converted the parental cells from low- into high-metastatic cells. TI-241 may regulate the expression of various genes as a transcription factor in the complex process of metastasis.

Amino Acid Sequence↗
PubMed1996

Potentiation of antitumor and antimetastatic activities of adriamycin by a novel N-alkylated dihydropyridine, AC394, and its enantiomers in colon cancer-bearing mice.

PURPOSE: We have previously shown that a series of N-alkylated 1,4-dihydropyridines potentiate the therapeutic efficacy of vincristine in vincristine-resistant P388 leukemia. The purpose of this study was to investigate the ability of one of the compounds, AC394, and its enantiomers to potentiate the antitumor activity of adriamycin against colon cancer cells in vitro and in vivo. METHODS: The effects of AC394 on potentiation of adriamycin cytotoxicity and enhancement of its accumulation were evaluated using colon 26, HCT-15 and MCF-7 cells. Furthermore, the activities of AC394 and its enantiomers were compared. We also studied the combined effects of (+)-AC394 and adriamycin on subcutaneously (s.c.)-implanted and liver metastasis tumor models. RESULTS: AC394 potentiated the cytotoxicity of adriamycin and enhanced its accumulation in colon cancer cells (colon 26 and HCT-15), which are known to express P-GP (P-glycoprotein) intrinsically. Enhancement of adriamycin accumulation by AC394 was found in s.c.-implanted colon 26 cells in vivo. Although both enantiomers of AC394 showed equal activity in vitro, (+)-AC394 was more effective than (-)-AC394 given orally. (-)-AC394 was found to be cleared more rapidly from the plasma than (+)-AC394. Thus, (+)-AC394 was evaluated for further study. Administration of (+)-AC394 significantly potentiated the antitumor activities of adriamycin in human colon cancer HCT-15 cells implanted s.c. Furthermore, in the liver metastasis model using colon 26 cells, a model completely resistant to adriamycin, the combination therapy of adriamycin with (+)-AC394 produced superior antitumor effects over adriamycin alone. CONCLUSIONS: A newly synthesized N-alkylated 1,4-dihydropyridine derivative, (+)-AC394, showed superior effects on the potentiation of adriamycin antitumor and antimetastatic activities in vivo. These results suggest that this combination may have therapeutic efficacy not only against primary colon cancers but also against metastatic liver cancer.

Animals↗
PubMed1996

Inhibitory effect of a spicamycin derivative, KRN5500, on the growth of hepatic metastasis of human colon cancer-producing tissue polypeptide antigen.

The inhibitory effect of KRN5500, a spicamycin derivative, on the growth of hepatic metastasis of the tissue polypeptide antigen (TPA)-producing human colon cancer COL-1 was examined in severe combined immunodeficient (SCID) mice. Prior to this chemotherapeutic study, we confirmed the high correlation coefficient (r = 0.86, P < 0.01) between plasma TPA levels in athymic nude mice bearing COL-1 and tumor volume. In the chemotherapy of experimental hepatic metastasis induced by intrasplenic injection of COL-1 cells, KRN5500 at 12 mg/kg per day was administered i.v. three times at 4-day intervals. From the start of chemotherapy (day 1), plasma TPA levels in the mice were significantly decreased from 8332 U/l to a minimum of 494 U/l on day 16 and were within the range for intact SCID mice (409-634 U/l). The mean tumor weight was 4.87 g in the liver of untreated mice on day 19 and 0.74 g, in the liver of KRN5500-treated mice, a significant difference, representing a tumor growth inhibition rate of 85%. These results suggest the usefulness of TPA as a tumor marker in an experimental xenograft model. The chemotherapeutic efficacy of KRN5500 against experimental hepatic metastasis indicates that it may be a useful drug for the treatment of patients with hepatic metastases of colon cancer.

Animals↗
PubMed1996

Transduction of the macrophage colony-stimulating factor gene into human multidrug resistant cancer cells: enhanced therapeutic efficacy of monoclonal anti-P-glycoprotein antibody in nude mice.

To develop a therapeutic modality for overcoming multidrug-resistant (MDR) cancer with anti-MDR1 antibody, we examined the effect of macrophage colony-stimulating factor (M-CSF) gene transfection into MDR AD10 cells on therapy of MDR cancer with anti-MDR1 antibody (MRK17) in nude mice. MDR human ovarian cancer (AD10) cells were transduced with the human M-CSF gene inserted into an expression vector to establish gene-modified cells capable of producing low (ML-AD10), intermediate (MM-AD10) nd high (MH-AD10) amounts of M-CSF. Systemic administration of MRK17 resulted in significant dose-dependent inhibition of subcutaneous growth of ML-AD10 tumors. In contrast, systemic administration of recombinant M-CSF in combination with MRK17 did not augment the therapeutic efficacy of MRK17 alone, but rather promoted the growth of the parent AD10 cells. To test the efficacy of in vivo M-CSF gene therapy combined with antibody, we mixed the parent AD10 cells with MH-AD10 cells producing a large amount of M-CSF, and inoculated the mixed cells subcutaneously. Treatment with MRK17 inhibited growth of the mixed cells more than that of the parent cells alone. Thus, combined therapy with anti-MDR1 mAb and M-CSF gene modification of MDR cancer cells may provide a new immunotherapeutic modality for overcoming MDR in humans.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
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

Modulation of multidrug resistance by SDZ PSC 833 in leukemic and solid-tumor-bearing mouse models.

P-Glycoprotein inhibitors, including the nonimmunosuppressive cyclosporin D analog SDZ PSC 833 (PSC 833), have been developed to circumvent multidrug resistance. In the present study, the potential of PSC 833 in reversing multidrug resistance was evaluated in various systemic treatment models with leukemic and solid-tumor-bearing mice. Having a relatively wide therapeutic window of daily p.o. doses from 12.5 to 75 mg/kg, PSC 833 significantly improved the antileukemic activity of the anticancer drugs adriamycin (ADM), vincristine (VCR) and etoposide (VP-16) given i.p. or i.v. against i.p.-inoculated vincristine-resistant P388 tumor (P388/VCR). PSC 833 in combination with i.p.-injected anticancer drugs in optimal schedule and dosage induced apparent cures in some leukemic mice, whereas no cures were obtained with the cyclosporin A/anticancer drug combinations. PSC 833 combined with i.v.-injected anticancer drugs was highly active, but not curative, against P388/VCR and parental P388 tumors (maximum T/C>175%) PSC 833 in combination with intravenous treatment with ADM showed prominent anti-solid-tumor activity against s.c.-inoculated colon adenocarcinoma 26 and human colorectal adenocarcinoma HCT-15. Against colon adenocarcinoma 26, the PSC 833/ADM combinations induced cure in two or three of six mice. PSC 833/ADM combinations significantly inhibited the growth of the tumor with maximum percent inhibitions of 83 and 73% in the early and advanced stages of the HCT-15 tumor models, respectively. The present study demonstrated that PSC 833 is highly active in potentiating the antitumor activity of systemically administered ADM, VCR and VP-16 against four murine and human tumors with a relatively wide therapeutic window of daily p.o. dose range of 12.5-100 mg/kg.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Inhibition of tumor cell invasion and matrix degradation by aminopeptidase inhibitors.

We investigated the effects of several types of aminopeptidase inhibitors on tumor cell-associated aminopeptidase activity and invasion. The aminopeptidase expressed by the human metastatic HT1080 fibrosarcoma cells was effectively suppressed by actinonin A, bestatin, leuhistin and matlystatin A, which are capable of inhibiting the purified aminopeptidase N, but not by arphamenine B specific for aminopeptidase B. The aminopeptidase N inhibitors inhibited HT1080 cells from degrading the subendothelial matrix and from invading into Matrigel in parallel with their aminopeptidase inhibitory activities. Matlystatin A, with multiple inhibitory activity against both aminopeptidase N and matrix metalloproteinases (MMP), was the most effective inhibitor of invasion. However, leuhistin and bestatin, without MMP inhibitory activity, also exhibited significant inhibition of invasion. The results suggest that aminopeptidase N plays a crucial role in the degradation and invasion of extracellular matrices by fibrosarcoma cells and that aminopeptidase inhibitors may be useful for preventing the spread of malignant tumors.

Aminopeptidases↗
PubMed1996

[Cancer chemotherapy and apoptosis].

Tumor cells undergo apoptotic cell death when treated with several chemotherapeutic agents. Since these agents, acting on different cellular targets, induce a similar pattern of cell death (apoptosis), it is suggested that a common signaling pathway of apoptosis could exist and that apoptosis resistance could cause a new form of multi-drug resistance in tumor cells. Although the mechanisms of apoptosis are not fully understood, the involvement of ICE/ced-3 family proteases in chemotherapy-induced apoptosis is strongly suggested. Identification of factors directly acting on these apoptosis pathway will offer new strategies in cancer chemotherapy.

Actins↗