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Biomedical subjects

N Saijo

Publications and source records attributed to N Saijo.

At least 199 records · Page 11Linked to original sources
PubMed1994

7-Ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxy camptothecin: mechanism of resistance and clinical trials.

The camptothecin derivative 7-ethyl-10-[4-(1-piperidino)-1-piperidino]-carbonyloxy camptothecin (CPT-11) has attracted the attention of clinicians because of its high antitumor activity against refractory solid cancers. We established two CPT-11-resistant cell lines, a non-small-cell lung-cancer cell line (PC-7/CPT-11) from the parental PC-7 line and an ovarian cancer cell line (HAC-2/CPT-11) from the parental HAC-2 line. The mechanisms of resistance to CPT-11 in PC-7/CPT-11 cells were reduced conversion of CPT-11 to its active metabolite SN-38 and point mutation topoisomerase I. Those in HAC-2/CPT-11 cells were reduction of topoisomerase I activity and decreased sensitivity of topoisomerase to topoisomerase I inhibitors. No point mutation of the topoisomerase was observed in HAC-2/CPT-11 cells. We conducted two phase I trials using CPT-11 in combination with other anticancer agents. One was a phase I trial of CPT-11 and cisplatin given with a fixed dose of vindesine to patients with advanced non-small-cell lung-cancer and the other was a phase I study on a topoisomerase-targeting combination of CPT-11 and etoposide (VP-16) in patients with various malignant solid tumors. The results of the first trial indicated that the recommended dose of CPT-11 for phase II studies was 80 mg/m2 combined with 3 mg/m2 vindesine on days 1 and 8 and 60 mg/m2 cisplatin on day 1. In the second trial, the recommended dose of CPT-11/VP-16 given with recombinant granulocyte colony-stimulating factor (on days 4-17) was found to be 60/60 mg/m2. In both trials, diarrhea and granulocytopenia were considered to be dose-limiting toxicities.

Amino Acid Sequence↗
PubMed1994

Characterization of an etoposide-resistant human ovarian cancer cell line.

Etoposide (VP-16) is one of the most important anticancer agents available and is used in many chemotherapeutic regimens. To characterize resistance to this drug, we established a VP-16-resistant human ovarian cancer cell line, SKOV3/VP, by continuous stepwise exposure of SKOV3 cells to VP-16. The degree of resistance to VP-16 of SKOV3/VP was about 25 times that of the parent cell line (SKOV3), and SKOV3/VP showed cross-resistance to teniposide, adriamycin, CPT-11, and vincristine. The accumulation of [3H]-VP-16 observed in SKOV3/VP cells was about half that seen in SKOV3 cells, and the accumulation of Adriamycin by this resistant cell line was also lower than that of its parent. Overexpression of neither the multidrug resistance gene mdr-1, the multidrug-resistance-associated protein (mrp) gene, nor P-glycoprotein was detected using reverse transcriptase-polymerase chain reaction analysis and flow cytometry with MRK-16, a monoclonal antibody against P-glycoprotein. The topoisomerase II activity of nuclear extracts from SKOV3/VP cells was lower than that from the parental cells, as was the amount of DNA topoisomerase II, demonstrated by immunoblotting. These results suggest that the mechanism responsible for the multidrug resistance of this cell line may be attributable to changes on its DNA topoisomerase II and to its reduced accumulation of the drugs as compared with the parental line SKOV3.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Apoptosis induced by etoposide in small-cell lung cancer cell lines.

The DNA fragmentation, a parameter of apoptosis, in non-small (NSCLC) and small (SCLC) cell lung cancer cell lines (N231 and PC-9) was evaluated. The DNA fragmentation in SCLC lines, but not in NSCLC lines, was observed in overgrown cells without exposure to anticancer drugs. In etoposide (VP-16)-treated N231 but not PC-9 cells, DNA fragmentation continued to increase up to 42 h, and the increase was dependent on the concentration of VP-16. The endonuclease activity of VP-16-treated N231, but not PC-9, cells required both Ca2+ and Mg2+ for full activity. It was elevated in a time- and concentration-dependent manner. As this activity was not affected by addition of cycloheximide, the activation of the endonuclease activity without protein synthesis may be involved in VP-16-induced cytotoxicity in N231.

Apoptosis↗
PubMed1994

Culture of retinoblastoma cells from clinical specimens: growth-promoting effect of 2-mercaptoethanol.

Establishment of new tumor cell lines is an important first step for biological studies of tumor cells. High success rates in establishing retinoblastoma cell lines have been reported when feeder-layer culture but not liquid-culture techniques were used. Liquid culture is, however, essential for studies in which feeder-layer cells are undesirable. In a previous study, we formulated a medium (RB-- medium), the components of which were almost identical to those of a soft-agar medium developed for colony formation of established retinoblastoma cell lines, in which one cell line from 12 primary retinoblastoma specimens was established. In this study, another medium (RB++ medium), RB-- medium to which 20 microM 2-mercaptoethanol and 375 microM asparagine were added, was tested for its ability to grow retinoblastoma cells from clinical specimens. In the RB++ medium, 6 cell lines from 16 primary sites, 2 from 2 intraocular-recurrent and 3 from 3 metastatic retinoblastomas grew for over a year. The major reason for the apparent improvement of the RB++ medium on the RB-- medium was demonstrated to be the addition of 2-mercaptoethanol.

Cell Division↗
PubMed1994

Malignant germ cell tumor of the mediastinum: a multimodality therapeutic approach.

Twenty-five patients with a malignant germ cell tumor of the mediastinum were treated at the National Cancer Center Hospital, Tokyo. Three patients had pure seminomas while 22 had a nonseminomatous histology. The treatment modalities consisted of surgery alone in 7 patients, surgery with chemotherapy and/or radiation in 14, and chemotherapy and/or radiation without surgery in 4. Cisplatin-based chemotherapy was administered in nine patients, one of whom successfully underwent high-dose chemotherapy with autologous bone marrow transplantation after resection of the tumor. A complete response was achieved in only five patients. The overall survival rate at 5 years was 33.5% and the median survival time was 51 weeks. Eight patients (32%), all of whom underwent surgery either with or without chemotherapy and/or radiation, were free of disease with a mean follow-up period of 439 weeks (72-1,120 weeks). The median survival times for 14 patients undergoing combined modality treatment, 7 patients undergoing surgery alone, and 4 patients undergoing chemotherapy and/or radiation were 83, 16, and 18 weeks, respectively.

Adolescent↗
PubMed1994

In vitro and in vivo cytogenetic effects of recombinant interleukin-2 on human lymphocytes.

To determine the cytogenetic effects of rIL-2, we investigated the rIL-2-induced sister chromatid exchange (SCE) and chromosomal aberrations in human peripheral lymphocytes in vitro and in patients given rIL-2 as a 24-hour infusion for 28 consecutive days. No significant increase in SCE frequency and chromosomal aberrations was observed after in vitro incubation of lymphocytes with 100 U/ml of rIL-2. A daily rIL-2 dose of 6.6 x 10(5) U/m2 did not induce any significant effect on SCE frequency and chromosomal aberrations while a marked increase was observed in the percentage of IL-2 receptor positive cells and HLA-DR positive cells. Although IL-2 therapy is only in developmental stage, our results suggest there is little or no potential mutagenic and/or carcinogenic hazard with this agent.

Aged↗
PubMed1994

A randomized prospective study of imipenem-cilastatin with or without amikacin as an empirical antibiotic treatment for febrile neutropenic patients.

To evaluate the effect of adding amikacin (AMK) to imipenem-cilastatin (IPM/CS), we conducted a randomized controlled trial in patients who experienced neutropenia (< 1,000/mm3) and fever (> 38 degrees C) induced by cancer chemotherapy. There were 70 patients who entered the trial; 34 and 36 patients received IPM/CS plus AMK (arm A) and IPM/CS (arm B), respectively. There was no significant difference in patient characteristics between the two groups. Among 67 evaluable patients, 29 of 32 (91%) and 25 of 35 (71%) responded to the antibiotics therapy in arm A and B, respectively, with EORTC criteria (p < .047). Median days of antibiotics administration and of febrile episode over 38 degrees C were not statistically significantly different between arm A and B. There was no patient with severe side effects, such as seizure, and 17 patients (30%) experienced emesis in both groups. These data suggest IPM/CS plus AMK is therapeutically superior to IPM/CS alone in patients with neutropenic fever induced by cancer chemotherapy.

Adult↗
PubMed1994

Characterization of a taxol-resistant human small-cell lung cancer cell line.

Taxol is a novel anticancer agent with activity against a broad range of tumors. It has a unique ability to stabilize polymerized tubulin into microtubule bundles within the cell. We have established a taxol-resistant human small-cell lung cancer cell line (H69/Txl) by exposing H69 cells to stepwise increases in taxol concentration. The resistance of H69/Txl cells to taxol was 4.7-fold that of the original H69 cells: the IC50 values for H69 and H69/Txl were 113.7 +/- 56.54 nM and 538.7 +/- 214.7 nM by the tetrazolium dye assay, respectively. Removal of the drug from the medium resulted in a 38% decrease in the growth rate of H69/Txl as compared with that in the presence of 30 nM taxol, suggesting that the growth of H69/Txl was partially dependent on taxol. H69/Txl showed higher sensitivity to vinca alkaloids such as vindesine, vincristine and vinblastine than the parental H69. There was no significant difference in intracellular [3H]taxol content between H69 and H69/Txl cells. No MDR-1 mRNA was detected in H69/Txl by the reverse transcription polymerase chain reaction. There was no significant difference of total and polymerized tubulin content between H69 and H69/Txl cells. Altered mobility of one of the alpha-tubulin isoforms in H69/Txl was revealed by using isoelectric focusing and Western blotting with anti-alpha-tubulin antibody. In H69, two alpha-tubulin isoforms were observed, whereas three were evident in H69/Txl, two of them comigrating with the isoforms of H69 and the other being more acidic. We observed the increased acetylation of alpha-tubulin in H69/Txl cells as compared with that in H69 cells. The acetylation of alpha-tubulin may be responsible for the taxol resistance and/or taxol-dependent growth of H69/Txl.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

A novel antitumor antibiotic, KW-2189 is activated by carboxyl esterase and induces DNA strand breaks in human small cell lung cancer cells.

KW-2189 has been selected as a lead compound for clinical trial among duocarmycin derivatives with structural similarity to CC-1065, a cyclopropylpyrroloindole. The purpose of this study was to examine the DNA-binding potency and the mechanisms of cytotoxicity of KW-2189. In order to analyze DNA-binding activity of KW-2189, plasmid pBR322 was treated with KW-2189 with or without pretreatment with carboxyl esterase, which we demonstrated to be an activating enzyme, and the products were examined by agarose gel electrophoresis and restriction enzyme analysis. Cytotoxic activity was examined by exposing a human small cell lung cancer cell line, NCI-H69 to KW-2189 with or without carboxyl esterase. Alkaline elution was performed to examine whether KW-2189 induces DNA strand breaks. DNA treated with KW-2189 and carboxyl esterase migrated faster than KW-2189-treated DNA, which migrated at the same rate as untreated DNA. In addition DNA treated with esterase-activated KW-2189 was protected from digestion by some restriction enzymes. KW-2189 showed concentration- and time-dependent growth inhibitory effect with IC50 values (drug concentration required for 50% growth inhibition) of 58 nM (96 h) to 1900 nM (1 h) in H69 cells. The IC50 values of 4-h exposure of H69 to KW-2189 with 0, 26, 130, 650 mU/ml carboxyl esterase were 460, 120, 30, and 7 nM, respectively. Time-dependent enhancement of cytotoxicity by carboxyl esterase was also observed. KW-2189 induced DNA strand breaks in H69 cells in a concentration-dependent manner around the IC50 value. We conclude that 1) KW-2189 is activated by carboxyl esterase to its active form(s), 2) activated KW-2189 has a stronger DNA-binding activity and cytotoxicity than KW-2189, 3) DNA cleavage is one of the major mechanisms of KW-2189-mediated cytotoxicity.

Antibiotics, Antineoplastic↗
PubMed1994

Rapid polymerase chain reaction assay to detect variation in the extent of gene-specific damage between cisplatin- or VP-16-resistant and sensitive lung cancer cell lines.

We previously established a rapid and facile polymerase chain reaction (PCR)-stop assay for quantitation of specific gene damage in very small numbers of cells. The present study investigated whether the PCR-stop assay was able to detect variation in the extent of DNA damage in transcribed active genes between cisplatin- or VP-16-resistant and sensitive cells. The assay demonstrated that about twice as much genetic damage occurs in PC-9 cells than in cisplatin-resistant PC-9/CDDP cells following cisplatin exposure and about 4.6 times more damage occurs in H69 than in VP-16-resistant H69/VP cells following VP-16 exposure. These results show that DNA damage, as detected by PCR-stop assay, correlates with cytotoxicity. In conclusion, the PCR-stop assay could be useful in detecting variation in DNA damage in specific genes.

Base Sequence↗
PubMed1994

In vitro and in vivo effects of cisplatin and etoposide in combination on small cell lung cancer cell lines.

The effects of cisplatin (CDDP) and etoposide (ETP) in combination were evaluated in vitro and in vivo using small cell lung cancer cell lines. The combination effects in vitro were investigated using isobologram analysis. Used together, CDDP and ETP showed a synergistic effect against cell growth on only 1 cell line (SBC-3), additive effects on 6 (SBC-2, SBC-5, Lu130, Lu134AH, Lu135T and H69) and an antagonistic effect on 1 (SBC-1). In the in vivo experiment, nude mice were inoculated with SBC-1, SBC-3 and SBC-5 cells. Two or 5 mg/kg CDDP and 10 or 30 mg/kg ETP were administered intraperitoneally alone and simultaneously in combination to nude mice. The in vivo effects of the combination were determined by comparing the observed growth ratio in mice treated with the combination with the expected value of this ratio calculated based on the assumption that the effects of the drugs were simply additive. According to this definition, synergistic effects were observed against all 3 tumors. Thus, the in vivo and in vitro effects differed. The toxicity of the combination therapy, which was analyzed by estimating the body weight change of mice, was no higher than that of CDDP or ETP alone. These results suggest that the excellent clinical effects of CDDP and ETP combination therapy may be attributable not to drug interaction at the cellular level but to the feasibility of combined use of them at full doses without overlapping side effects.

Animals↗
PubMed1994

Genistein, a tyrosine kinase inhibitor, decreased the affinity of p56lck to beta-chain of interleukin-2 receptor in human natural killer (NK)-rich cells and decreased NK-mediated cytotoxicity.

Intracellular signal transduction has been reported to be triggered by phosphorylation of interleukin-2 (IL-2) receptor by IL-2. In order to clarify the effect of tyrosine phosphorylation of IL-2 receptors on cell-mediated cytotoxicity by natural killer (NK) cells, we studied the effect of a tyrosine kinase inhibitor, genistein, on the lethal effects of NK-rich cells for K562 cells. Exposure of NK-rich cells to IL-2 (100 U/ml) for 3 days increased their cytotoxicities against K562 cells. The effect was reduced in the presence of 10 micrograms/ml of genistein. Samples immunoprecipitated by anti-IL-2R beta antibodies were prepared from NK-rich fractions with or without exposure to IL-2 and/or genistein. Coprecipitated proteins with 75, 65, and 56 kDa were detected with an antiphosphotyrosine antibody. The amount of phosphorylated tyrosine residues of 56-kDa protein, which was predominantly detected in NK-rich cells, was remarkably increased by IL-2 treatment. The enhanced phosphorylation of 56-kDa protein was reduced by the presence of genistein. These results suggested that IL-2 increased tyrosine phosphorylation and the affinity to IL-2R beta of the 56-kDa proteins in NK-rich cells. Immunoprecipitated samples by anti-IL-2R beta were reblotted with anti-p56lck antibody and revealed that the 56-kDa protein was identified to be p56lck. The increase of coprecipitated p56lck with anti-IL-2R beta antibody by the treatment with IL-2 suggested that the affinity of p56lck to IL-2R beta was increased by IL-2 in NK-rich cells. The amount of coprecipitated p56lck with IL-2R beta was reduced in the sample exposed to genistein. The affinity of p56lck to IL-2R beta was considered to be regulated by IL-2-induced tyrosine phosphorylation. Our results demonstrated a potential role for tyrosine kinase, p56lck, in the signaling events that regulate the cytotoxicity by NK-rich cells.

Cytotoxicity, Immunologic↗
PubMed1994

Human metallothionein isoform gene expression in cisplatin-sensitive and resistant cells.

Overexpression of metallothioneins (MTs) has been observed in some cis-diamminedichloroplatinum (CDDP)-resistant cells. We have developed oligonucleotide probes for each of the six non-neuronal human MT (hMT) isoforms and used them to assay hMT isoform expression in three pairs of CDDP-resistant and -sensitive human carcinoma cell lines, i.e., SCC25/CP versus SCC25 cells, H69/CP versus H69 cells, and SW2/CP versus SW2 cells. We found a 9-fold increase in basal hMT-IIa mRNA levels and a 5-fold increase in hMT-le mRNA levels in SCC25/CP cells, compared with SCC25 cells. Nuclear run-on studies also revealed a 3-fold increase in hMT-IIa transcription rate. Basal hMT-IIa steady state mRNA levels were 2-3.6-fold greater in H69/CP and SW2/CP cells, compared with their parental cells. No significant basal expression of hMT-Ia, -Ib, -If, or Ig was detected in any cells, suggesting that overexpression of these isoforms was not commonly associated with the CDDP-resistant phenotype. Levels of constitutively expressed hMT isoforms, as well as hMT-If, could be elevated by treatment of all cells with 100 microM zinc. The universal overexpression of hMT-IIa suggests a role of this particular isoform in CDDP resistance. Using our isoform-specific hMT-IIa probe and the demethylating agent 5'-azacytidine (AZC), we found that AZC pretreatment increased basal hMT-IIa mRNA levels in SCC25 but not SCC25/CP cells, suggesting that DNA hypomethylation was responsible for higher basal hMT-IIa mRNA levels in SCC25/CP cells. AZC had little or no effect on hMT-If or -Ig expression. Limited restriction analysis by methylation-sensitive enzymes, however, revealed no obvious differences in the methylation status of the hMT-IIa promoter in either SCC25 or SCC25/CP cells.

Azacitidine↗
PubMed1994

Preliminary evaluation of the new tumor marker, CYFRA 21-1, in lung cancer patients.

Serum samples from 137 lung cancer patients were examined by RIA to evaluate the clinical efficacy of the new tumor marker, CYFRA 21-1, which could identify the soluble fragment of cytokeratin 19. The cut-off value was determined to be 2.2 ng/ml according to the receiver operating characteristic curve. The sensitivity, specificity and accuracy of the RIA for CYFRA 21-1 were 57.7, 91.9 and 64.9%, respectively. The serum concentration of CYFRA 21-1 and the sensitivity of the assay increased as the disease progressed. Histologically, the sensitivity was highest for squamous cell carcinomas (SQ) (76.5%) in comparison with adenocarcinomas (47.8%) and small cell lung cancers (42.1%) (P < 0.01, P < 0.05, respectively). The sensitivities for SQ were 60.0, 83.3, 80.0 and 100% at stages I, II, III and IV, respectively. When compared with CEA (45.3%) and squamous cell carcinoma related antigen (SCC) (22.6%) in all lung carcinomas, CYFRA 21-1 showed the highest sensitivity (57.7%), (P < 0.05, P < 0.01, respectively). In SQ, the sensitivity of the CYFRA 21-1 RIA was significantly higher than that of the assay for SCC (47.1%) (P < 0.05). In patients with adenocarcinomas, the sensitivity of the CYFRA 21-1 assay was almost the same as that for CEA (49.3%). In a combination of CYFRA 21-1 and CEA for non-small cell lung cancers (NSCLC), the sensitivity and accuracy increased to 75.4 and 78.1%, respectively, although the specificity decreased to 86.5%. It is concluded that CYFRA 21-1 could replace SCC, a less satisfactory tumor marker, for SQ of the lung. The potentiality of the combination of CYFRA 21-1 and CEA for NSCLC should be estimated using larger samples in the near future.

Adenocarcinoma↗
PubMed1994

[Microtubules and antineoplastic drugs].

Microtubules, which are composed of polymerized tubulin dimers, play an important role in various cell functions. For example, they maintain cell shape, form mitotic spindles in M phase of cell cycle, and carry an axonal transport in nerve cells. Microtubules have also been an important target of cancer chemotherapy. Vinca alkaloids depolymerize microtubules, the mechanisms of which action have extensively been investigated recently. Clinical trials of vinorelbine (navelbine), a new semisynthetic vinca alkaloid, are ongoing in Japan. One of advantages of the drug is reduced risk of neurotoxicity. Estramustine may act on microtubule-associated proteins (MAPs) as well as tubulin. It shows additive or synergistic cytotoxicity preclinically when used in combination with vinblastine. This combination was active against hormone-refractory prostate cancer. Another novel drug rhizoxin, which has a similar mechanism of action to that of vinca alkaloids, is also a promising cytotoxic agent and is examined clinically in Europe. Taxanes, which include paclitaxel (Taxol) and taxotere, are interesting drugs because they promote polymerization of tubulin and stabilize microtubules. They show promising antitumor activity against breast, ovarian and lung cancers. Phase I and II trials are ongoing in Japan. Paclitaxel may also potentiate cytotoxicity of radiation. There are several mechanisms of resistance to microtubule-acting drugs. One is multidrug resistance mediated by P-glycoprotein. Other mechanisms include mutation of tubulin.

Animals↗
PubMed1994

Concurrent cisplatin-etoposide chemotherapy plus thoracic radiotherapy for limited-stage small cell lung cancer. Japanese Lung Cancer Chemotherapy Group in Japanese Clinical Oncology Group.

A recent approach in the treatment of limited-stage small cell lung cancer (LDSCLC) has involved a combined modality of chemotherapy and chest irradiation. In using the modality, the study of scheduling methods for combining chemotherapy and radiotherapy should lead to other trials of combined modalities against LDSCLC since it is the most basic issue to be evaluated. We have thus conducted a multicenter phase II trial of concurrent cisplatin-etoposide (PVP) chemotherapy and radiotherapy for LDSCLC to determine the effects of the concurrent administration of a PVP regimen and chest irradiation on response rate, relapse, survival and treatment toxicity. The chemotherapy regimen consisted of a four-week cycle: cisplatin (80 mg/m2, given intravenously on day 1) and etoposide (100 mg/m2, given intravenously on days 1-3). This cycle was given four to six times within six months. Chest irradiation to the primary tumors at both the hili and the mediastinum was administered in standard fractions on days 2-12 in the first cycle of chemotherapy and on days 29-47 in the second cycle, with a total dose of 40-50 Gy. Prophylactic cranial irradiation was performed among complete remission (CR) or good partial remission (PR) patients after completion of the concurrent therapy. A total of 66 patients were entered into the trial and 59 were evaluated. The concurrent therapy induced an overall response rate of 94.9% in 59 patients: 24 patients, 40.7% CR, 32 patients, 54.2% PR. The median response duration was 8.7 months, and the median survival time for all eligible patients was 14.8 months. The percentage of patients with two-year survival periods was 20. A local relapse within the irradiated area was seen in only 22% of relapse patients. Brain metastases occurred in 24% of patients. Four of 32 patients treated with prophylactic cranial irradiation had brain metastases. Toxic effects, chiefly grades 3 and 4 leukopenia, as established by the World Health Organization, were detected in all treated patients. Other toxicities, including radiation-induced esophagitis and pneumonitis, were deemed almost acceptable. We concluded concurrent treatment of a PVP regimen with chest irradiation to be a feasible and beneficial therapy with an efficacy compatible to that of other published reports. The outcome of this protocol warrants further investigation to determine the optimal type of schedule for concurrent chemoradiotherapy against LDSCLC.

Adult↗