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T Tsuruo

Publications and source records attributed to T Tsuruo.

At least 55 records · Page 3Linked to original sources
PubMed2000

Cyclooxygenase-2 overexpression correlates with tumour recurrence, especially haematogenous metastasis, of colorectal cancer.

Epidemiological studies have demonstrated that nonsteroidal anti-inflammatory drugs (NSAIDs), known to inhibit cyclooxygenase (COX), reduce the risk of colorectal cancer. COX is a key enzyme in prostaglandin biosynthesis, and two isoforms of COX, COX-1 and COX-2, have been identified. Recently COX-2 has been reported to frequently overexpress in colorectal neoplasms and to play a role in colorectal tumorigenesis and tumour progression. In this study, using immunohistochemistry, we examined COX-2 expression in advanced human colorectal cancer and its correlation with clinicopathological features. COX-2 expression was observed mainly in the cytoplasm of cancer cells in all the specimens examined, but some stromal cells and endothelial cells were also stained. According to the grade of COX-2 expression of the cancer cells, patients were divided into high- and low-COX-2 expression groups. High-COX-2 expression significantly correlated with tumour recurrence, especially haematogenous metastasis. These results suggest that a selective COX-2 inhibitor can be a novel class of therapeutic agents not only for tumorigenesis but also for haematogenous metastasis of colorectal cancer. To our knowledge, this is the first report on the correlation between COX-2 overexpression and recurrence of colorectal cancer.

Aged↗
PubMed2000

Analysis of novel metastasis-associated gene TI-227.

TI-227 is a cancer metastasis-associated gene isolated from the B16-F10 mouse melanoma subline that preferentially metastasizes to the lung following intravenous injection. TI-227 is more highly expressed in the B16-F10 and colon26-nl17 sublines, which preferentially metastasize to the lung following intravenous injection, than in the B16-BL6 and colon26-nl22 sublines, which preferentially metastasize to the lung following subcutaneous injection. Since TI-227 could not be detected in normal tissues, there is a possibility that it is expressed specifically in tumors that preferentially metastasize to the lung following intravenous inoculation. Although the 5' end of TI-227 was analyzed, its total sequence contained no obvious open reading frame. However comparison with the isolated human counterpart, TI-227H gene, revealed a highly homologous region near the 3' end, which was expected to contain a very short open reading frame.

Adenocarcinoma↗
PubMed2000

Identification and characterization of a deletion mutant of DNA topoisomerase I mRNA in a camptothecin-resistant subline of human colon carcinoma.

In previous studies, we established two camptothecin (CPT)-resistant sublines, HT-29 / CPT and St-4 / CPT, from the human colon cancer cell line HT-29 and the human stomach cancer cell line St-4, respectively. Cellular contents of DNA topoisomerase I (topo I) in the resistant cells were eight-fold less than those in the corresponding parental lines. In this study, we have shown expression of two species of the TOP1 mRNA in HT-29 / CPT. The longer mRNA (4.0 kb) is the wild-type TOP1 mRNA, and the shorter mRNA (3.3 kb) proved to have a deletion of 672 bp (nucleotides 58 - 729 or 59 - 730) that caused the in-frame deletion of amino acids 20 - 243 of human topo I. The deleted region is identical to exons 3 - 9 of the TOP1 gene. The expression level of the 3.3-kb mRNA was similar to that of the wild-type mRNA in HT-29 / CPT. St-4 / CPT expressed only the wild-type TOP1 mRNA in lesser amounts than did St-4. Mouse NIH3T3 cells transfected with the wild-type TOP1 cDNA showed higher sensitivity to CPT than the parental cells, whereas those transfected with the deleted TOP1 cDNA showed levels similar to those of the parental cells. Expression of the exogenous TOP1 mRNA was confirmed; however, expression of the truncated topo I was not detected in cells transfected with the deleted TOP1 cDNA. These results suggest that the expression of the deleted TOP1 mRNA led to the low expression of CPT-sensitive topo I in the resistant cells.

Amino Acid Sequence↗
PubMed2000

Multidrug resistance reversal activity of taxoids from Taxus cuspidata in KB-C2 and 2780AD cells.

Some non-taxol-type taxoids having neither an oxetane ring at C-4 and C-5 nor an N-acylphenyl-isoserine group at C-13, such as taxuspine C, 2'-desacetoxyaustrospicatine, and 2-desacetoxytaxinine J, which were isolated from the Japanese yew Taxus cuspidata, increased cellular accu-mulation of vincristine (VCR) in multidrug-resistant 2780AD cells as potently as verapamil, and efficiently inhibited [(3)H]azidopine photolabeling of P-glycoprotein (P-gp). Taxuspine C, 2'-desacetoxyaustrospicatine, and 2-desacetoxytaxinine J at 10 microM completely reversed the resistance to colchicine, VCR, and taxol in KB-C2 cells, which overexpress P-gp, while taxinine and taxinine M showed no effect. Taxuspine C, 2'-desacetoxyaustrospicatine, and 2-desacetoxytaxinine J may be candidate pharmaceuticals for reversing multidrug resistance (MDR) and also may be good modifiers of MDR in cancer chemotherapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Inhibitory effect of ATF3 antisense oligonucleotide on ectopic growth of HT29 human colon cancer cells.

ATF3 is a transcription factor belonging to the Jun / Fos family whose mouse homologue (TI-241) was isolated, using the differential screening method, from B16 mouse melanoma cells as a blood-borne metastasis-associated gene. Here we show the tumorigenicity-inhibiting effect of an antisense oligonucleotide designed to reduce the expression of ATF3 in HT29 colon cancer cells. HT29 cells were reported to metastasize to the skin after intravenous inoculation. The antisense oligonucleotide inhibited cell attachment to the collagen-coated floor of the plates and invasion of HT29 cells in vitro, which are thought to be two important factors in the process of cancer metastasis and ectopic tumor growth. While the antisense oligonucleotide had no effect on cell growth of HT29 cells in vitro, mice that were inoculated subcutaneously with HT29 cells and treated with the antisense oligonucleotide survived longer than the control mice due to the inhibition of tumor growth in vivo. These show that ATF3 plays an important role in the ectopic growth / metastasis of HT29 colon cancer cells.

Activating Transcription Factor 3↗
PubMed2000

MMP-1 is a prognostic marker for hematogenous metastasis of colorectal cancer.

BACKGROUND: Degradation of basement membrane and extracellular matrix by matrix metalloproteinases (MMPs) is believed to be an essential step in the complicated process of hematogenous metastasis. MMP-1 is a member of collagenases, a family of MMPs that degrades collagens type I, II, and III, main components of the interstitial stroma. The purpose of this study was to investigate the expression of MMP-1 in colorectal cancer and its correlation with hematogenous metastasis. Patients and Methods. We examined 133 cases of colorectal cancer (Dukes A: 72; Dukes B: 26; Dukes C: 23; Dukes D: 12). Sections were cut from formalin-fixed, paraffin-embedded samples containing the deepest site of cancer invasion and stained immunohistochemically with a monoclonal antibody to MMP-1. According to the area of the tumor that was stained, patients were divided into high- and low-MMP-1 expression groups. RESULTS: MMP-1 expression was observed in the cytoplasm of cancer cells, some stromal cells, and a few normal epithelial cells of colonic mucosa. High MMP-1 expression was found in 47 (35.3%) cases and low in 86 (64.7%). Hematogenous metastasis was identified in 14 (29.8%) of high-MMP-1 groups and 12 (13.9%) of low-MMP-1 groups. MMP-1 expression significantly correlated with hematogenous metastasis of colorectal cancer, but no correlation was found between MMP-1 expression and the other clinicopathological features investigated. CONCLUSIONS: MMP-1 expression may be a novel marker for hematogenous metastasis of colorectal cancer, and its inhibition may be a strategy for prevention of metastasis.

Adult↗
PubMed2000

Efficient introduction of macromolecules and oligonucleotides into brain capillary endothelial cells using HVJ-liposomes.

In this study, we examined the feasibility of introducing macromolecules into cultured mouse brain capillary endothelial cells (MBEC4 cells) by utilizing the hemagglutating virus of Japan (HVJ)-liposomes with fusogenic activity. We used fluorescein isothiocyanate dextran (FITC-Dextran) and FITC-labeled oligodeoxynucleotide (FITC-ODN) as models of a macromolecule and an ODN, respectively. Intracellular fluorescence appeared rapidly after the exposure of MBEC4 cells to FITC-Dextran-containing HVJ-liposomes, and remained detectable for at least 3 days. Only a control level of intracellular fluorescence was seen after treatment with FITC-Dextran alone, FITC-Dextran with empty HVJ-liposomes or FITC-Dextran-containing liposomes without fusogenic activity. In the early phase after administration (0-30 min), the introduction of FITC-Dextran into MBEC4 cells by the HVJ-liposome method resulted in a rapid and time-dependent increase of intracellular fluorescence intensity. Moreover, FITC-ODN was also introduced into MBEC4 cells by the HVJ-liposome method, although FITC-ODN alone was not introduced. These results indicate that the HVJ-liposome method is useful for the efficient introduction of macromolecules, including ODN, into brain capillary endothelial cells.

Animals↗
PubMed2000

[Development of molecular targeting drugs for the treatment of cancer-therapeutic potential and issues to be addressed in global development].

A survey of cancer treatment in a sample of hospitals > 100 beds conducted in 1998 compared with experience in the US showed that good progress has been achieved in Japan in the screening and early treatment of gastric cancer, and that the prognosis for breast cancer is better than in the West. Although in the past, the cytotoxic therapies available to physicians in Japan vs the West have been different, recent acceleration of regulatory review will result in a convergence of treatment paradigms and some improvement in acute response in many tumour types. However, world wide there is a need for new improved therapies in all cancers evaluated. Particular needs are in the management of NSCLC, advanced disease and cancers which form micrometastases. The eventual hope is that cancer can be turned from a lethal disease into a chronic disease where patients maintain a good QOL. Apart from anti hormonal therapies, the usual approach has been to kill the cancerous cells. However, the new approaches to intervening in the growth and migration of cancerous cells or the host tissue response by molecular targeting offer the promise of achieving a step change in therapy. Although EGF tyrosine Kinase inhibitors such as ZD 1839 have been shown to cause a conventional tumour response in NSCLC, many of these new approaches are unlikely to show a short term response even if they have the capacity to affect tumour development and increase disease free survival. Some compounds will require combination therapy with a conventional cytotoxic or radiotherapy to show their full benefit. For conventional cytotoxics, the usual approach to development has been to select the maximum tolerated dose and then evaluate the efficacy in advanced disease. However, for the new approaches which will not have such severe dose limiting toxicities, it will be necessary to select a surrogate marker of the intended biological effect to select the optimal biological dose (OBD) and dose regimen in phase I/II studies for further evaluation in phase II or III studies which are designed to show the expected patient benefit. The tumour target, the stage of the disease and the possible need for concomitant therapy will also have to be considered according to the mechanism of action of the product.

Angiogenesis Inhibitors↗
PubMed1999

p21Waf1/Cip1 acts in synergy with bcl-2 to confer multidrug resistance in a camptothecin-selected human lung-cancer cell line.

The realization that chemotherapeutic agents induce apoptosis raises the concern that tumors resistant to chemotherapy are unable to initiate the apoptotic program. In the present study, we examined the apoptosis-resistance mechanism of a multidrug-resistant cell line, A549/CPT, which was established from the human lung-cancer cell line A549 by in vitro selection with gradually increased camptothecin (CPT) concentrations. We found that A549/CPT cells were resistant to anti-cancer drug-induced apoptosis in which caspase-3-like protease activity was attenuated remarkably, compared with parental A549 cells. We observed 2 mechanisms associated with apoptosis resistance in A549/CPT cells: over-expression of anti-apoptotic bcl-2 and elevated expression of p21Waf1/Cip1. Transfection of either bcl-2 or p21Waf1/Cip1 cDNA into parental A549 cells resulted in resistance to apoptosis. Furthermore, the co-treatment of p21Waf1/Cip1 and bcl-2 anti-sense oligodeoxy-nucleotides restored drug susceptibility in A549/CPT cells more effectively than either one of them alone. These results indicate that co-induction of bcl-2 and p21Waf1/Cip1 in A549/CPT cells may be involved in acquired drug resistance by inhibiting caspase-mediated apoptosis. Agents aimed at preventing both bcl-2 and p21Waf1/Cip1 expression may increase the efficiency of chemotherapy.

Apoptosis↗
PubMed1999

A human IAP-family gene, apollon, expressed in human brain cancer cells.

IAP is a family of protein that has baculovirus IAP repeat (BIR) domains and inhibits apoptosis. We found a human IAP family gene, which we named Apollon, encoding a huge protein (530 kDa) that contains a single BIR domain and a ubiquitin-conjugating enzyme domain, that is a human homolog of BRUCE. Apollon protein was expressed in four of six brain cancers (gliomas), and one of five ovarian cancers in 38 human cancer cell lines that we examined. Among the brain cancer cell lines, SNB-78 expressed a high level of Apollon, and this cell line shows resistance against various anticancer drugs. Treating SNB-78 cells with antisense oligonucleotide against Apollon reduced the expression of Apollon protein, and significantly sensitized the cells to apoptosis induced by cisplatin and camptothecin. These results suggest that Apollon protects SNB-78 cells from undergoing apoptosis and, at least in part, plays a role in tumorigenesis and drug resistance of this cell line.

Amino Acid Sequence↗
PubMed1999

Conserved BRCT regions of TopBP1 and of the tumor suppressor BRCA1 bind strand breaks and termini of DNA.

The BRCT region, the carboxyl-terminus of BRCA1 (the breast cancer susceptibility gene 1 product), is a ubiquitous region homologous to regions in DNA repair enzymes and cell cycle regulators. We showed that the BRCT regions bound DNA fragments, using the TopBP1 protein (topoisomerase II binding protein 1), with eight BRCTs as a model protein. The bindings were independent of DNA sequences, forms of DNA termini and energy. The BRCT-DNA complex showed resistance to an exonuclease, indicating that BRCT bound DNA breaks. The BRCTs also bound DNA nicks, suggesting that BRCTs play an important role in detection of both single- and double-strand DNA breaks or ends. On the other hand, BRCTs did not bind circular intact DNA. BRCTs of BRCA1 also bound DNA termini. Since some BRCTs are unique general elements in some tumor suppressions, these findings will reveal novel aspects of the tumor suppression mechanism.

BRCA1 Protein↗
PubMed1999

FJ5002: a potent telomerase inhibitor identified by exploiting the disease-oriented screening program with COMPARE analysis.

To facilitate the search for candidate telomerase inhibitors, we exploited the database of the disease-oriented screening program (DOS) available in our facility by using COMPARE analysis. In primary and arbitrary screening, we were able to identify the alkaloid berberine as a moderate inhibitor with 50% inhibition at approximately 35 microM. Using this alkaloid as a seed compound in COMPARE resulted in the identification of other berberine-like compounds and mitochondria-accumulating agents as highly related to berberine. Among these compounds, MKT077, a rhodacyanine derivative currently under Phase I clinical trials, showed a potent inhibitory effect with 50% inhibition at approximately 5 microM. With MKT077 as an upgraded seed for a new round of COMPARE analysis, we identified rhodacyanine FJ5002, a close derivative of MKT077, as the most potent telomerase inhibitor with 50% inhibition at approximately 2 microM. Long-term cultivation of U937, a human leukemia cell line, with subacute concentrations of FJ5002 resulted in population-doubling dependent changes characterized by progressive telomere erosion (from approximately 10 to approximately 4.0 kb), increased chromosome abnormalities, and senescence/crisis-like features. These results indicated that FJ5002 is a genuine and effective antitelomerase agent.

Antineoplastic Agents↗
PubMed1999

Potent antitumor activity of MS-247, a novel DNA minor groove binder, evaluated by an in vitro and in vivo human cancer cell line panel.

We synthesized a novel anticancer agent MS-247 (2-[[N-[1-methyl-2-[5-[N-[4-[N,N-bis(2-chloroethyl) amino] phenyl]] carbamoyl]-1H-benzimidazol-2-yl] pyrrol-4-yl] carbamoyl] ethyldimethylsulfonium di-p-toluenesulfonate) that has a netropsin-like moiety and an alkylating residue in the structure. We evaluated antitumor activity of MS-247 using a human cancer cell line panel coupled with a drug sensitivity database and subsequently using human cancer xenografts. The average MS-247 concentration required for 50% growth inhibition against a panel of 39 cell lines was 0.71 microM. The COMPARE analysis revealed that the differential growth inhibition pattern of MS-247 significantly correlated with those of camptothecin analogues and anthracyclins, indicating that MS-247 and the two drug groups might have similar modes of action. MS-247 exhibited remarkable antitumor activity against various xenografts. A single i.v. injection of MS-247 significantly inhibited the growth of all 17 xenografts tested, which included lung, colon, stomach, breast, and ovarian cancers. In many cases, MS-247 was more efficacious than cisplatin, Adriamycin, 5-fluorouracil, cyclophosphamide, VP-16, and vincristine and was almost comparable with paclitaxel and CPT-11; these are the most clinically promising drugs at present. MS-247 was noticeably more effective than paclitaxel (in HCT-15) and CPT-11 (in A549, HBC-4, and SK-OV-3). The toxicity of MS-247, indicated by body weight loss, was reversible within 10 days after administration. The MS-247 mode of action showed DNA binding activity at the site where Hoechst 33342 bound, inhibited topoisomerases I and II (as expected by the COMPARE analysis) blocked the cell cycle at the G2-M phase, and induced apoptosis. These results indicate that MS-247 is a promising new anticancer drug candidate to be developed further toward clinical trials.

Animals↗
PubMed1999

Antitumor activity and novel DNA-self-strand-breaking mechanism of CNDAC (1-(2-C-cyano-2-deoxy-beta-D-arabino-pentofuranosyl) cytosine) and its N4-palmitoyl derivative (CS-682).

We have studied the antitumor activity and the novel DNA-self-strand-breaking mechanism of CNDAC (1-(2-Ccyano-2-deoxy-beta-D-arabino-pentofuranosyl)cytosine) and its N4-palmitoyl derivative (CS-682). In vitro, CS-682 showed strong cytotoxicity against human tumor cells comparable with that of CNDAC; both compounds displayed a similar broad spectrum. In vivo, however, orally administered CS-682 showed a more potent activity against human tumor xenografts than CNDAC, 5'-deoxy-5-fluorouridine, 5-fluorouracil and 2',2'-difluorodeoxycytidine. Moreover, CS-682 was effective against various human organ tumor xenografts at a wide dose range and with low toxicity, and was effective against P388 leukemic cells resistant to mitomycin-C, vincristine, 5-fluorouracil or cisplatin in syngeneic mice. CNDAC, an active metabolite of CS-682, had a prolonged plasma half-life after repeated oral administrations of CS-682 but not after oral administrations of CNDAC itself. This difference may partially explain the higher antitumor activity of CS-682 relative to CNDAC. In both CNDAC- and CS-682-treated carcinoma cells, CNDAC 5'-triphosphate (CNDACTP) was generated and incorporated into a DNA strand. High performance liquid chromatography (HPLC) and mass spectrometric analysis of the nucleosides prepared by digestion of the DNA from the CNDAC-treated cells detected ddCNC (2'-Ccyano-2',3 '-didehydro-2',3 '-dideoxycytidine), which was shown to be generated only when the self-strand-breakage of CNDACTP-incorporated DNA occurred. The cytotoxicity of CNDAC was completely abrogated by the addition of 2'-deoxycytidine and was low against cells with decreased deoxycytidine kinase. Our results suggest that CNDAC is converted to CNDACMP by deoxycytidine kinase and that the resulting CNDACTP incorporated into a DNA strand as CNDACMP may induce DNA-self-strand-breakage. This novel DNA-self-strand-breaking mechanism may contribute to the potent antitumor activity of CS-682.

Administration, Oral↗
PubMed1999

NH2-terminal BH4 domain of Bcl-2 is functional for heterodimerization with Bax and inhibition of apoptosis.

The Bcl-2 family proteins comprise pro-apoptotic as well as anti-apoptotic members. Heterodimerization between members of the Bcl-2 family proteins is a key event in the regulation of apoptosis. We report here that Bcl-2 protein was selectively cleaved by active caspase-3-like proteases in CTLL-2 cell apoptosis in response to interleukin-2 deprivation. Structural and functional analyses of the cleaved fragment revealed that the NH2-terminal region of Bcl-2 (1-34 amid acids) was required for its anti-apoptotic activity and heterodimerization with pro-apoptotic Bax protein. Site-directed mutagenesis of the NH2-terminal region showed that substitutions of hydrophobic residues of BH4 domain resulted in the loss of ability to form a heterodimer with Bax. Particularly instructive was that the V15E mutant of Bcl-2, which completely lost the ability to form a heterodimer with Bax, failed to inhibit Bax- and staurosporine-induced apoptosis. Our results suggest that the BH4 domain of Bcl-2 is critical for its heterodimerization with Bax and for exhibiting anti-apoptotic activity. Therefore, agents interferring with the critical residues of the BH4 domain may provide a new strategy in cancer therapy by impairing Bcl-2 function.

Amino Acid Sequence↗
PubMed1999

Hypoxia up-regulates telomerase activity via mitogen-activated protein kinase signaling in human solid tumor cells.

Solid tumor cells are often exposed to hypoxia in vivo, which has been suggested to promote genetic instability in those cells. Telomere elongation by telomerase is implicated in chromosome stabilization in immortal cells. Here we found that hypoxia enhanced telomerase activity in the solid tumor A2780 and HT-29 cells but not in the leukemia U937 cells. The telomerase activation correlated with activation of mitogen-activated protein kinase (MAPK) and c-fos expression. The MEK1 inhibitor PD98059 repressed telomerase activation in the hypoxic cells. Consistently, a dominant negative MEK1 inhibited telomerase activation by hypoxia. Finally, we found a good correlation between telomerase activation and resistance to apoptotic cell death under hypoxic conditions. These findings indicate that hypoxia up-regulates telomerase activity via MAPK cascade signaling especially in solid tumor cells and suggest that solid tumor cells might enhance the telomerase activity as a stress response against genotoxicity induced by hypoxia.

Apoptosis↗
PubMed1999

Combined therapy with anti-P-glycoprotein antibody and macrophage colony-stimulating factor gene transduction for multiorgan metastases of multidrug-resistant human small cell lung cancer in NK cell-depleted SCID mice.

Our aim was to determine the antimetastatic potential of anti-P-glycoprotein (P-gp) antibodies (Abs) against multidrug-resistant (MDR) human small cell lung cancer (SCLC) cells expressing P-gp. Human SCLC cells H69 (P-gp negative) and its etoposide-resistant variant H69/YP (P-gp positive) were used. H69 and H69/VP cells injected i.v. metastasized to the liver, kidneys and systemic lymph nodes of NK cell-depleted severe combined immunodeficient (SCID) mice. H69/VP cells, but not H69 cells, were resistant to treatments with vindesine. Treatment with mouse-human chimeric anti-P-gp Ab (MH162) and its mouse counterpart (MRK-16) reduced metastasis of H69/VP cells in various organs and prolonged the survival of tumor-bearing mice, although they were less effective if injected at late times (after 28 days). Treatment with another mouse anti-Pgp Ab, MRK-17, was effective only against liver metastasis. MH162 and MRK-16 efficiently induced Ab-dependent cellular cytotoxicity (ADCC) by peritoneal macrophages against H69/VP cells in vitro, but MRK-17 was less effective, in accordance with their in vivo antimetastatic potential. Gene transfection of macrophage colony-stimulating factor (M-CSF) into H69/VP cells to augment macrophage-mediated ADCC resulted in inhibition of metastasis to the liver and lymph nodes, but not kidneys. Combined treatment with a low dose of MRK-16 completely cured metastasis of M-CSF transfectant, but not of the mock transfectant. Our findings suggest that while anti-P-gp Abs had antimetastatic potential against SCLC cells expressing P-gp, combined treatment with M-CSF gene transduction to augment the therapeutic efficacy of anti-P-gp Abs may be beneficial for eradicating metastatic MDR SCLC in humans.

ATP Binding Cassette Transporter, Subfamily B, Mem↗