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Biomedical subjects

R Kanamaru

Publications and source records attributed to R Kanamaru.

At least 91 records · Page 5Linked to original sources
PubMed1990

The changes in the levels of dihydrofolate reductase mRNA and its gene dosage in 5-fluorouracil-resistant L1210 cells.

5-Fluorouracil (5-FU)-resistant L1210 cell line (L1210/5-FU-1) was established in this laboratory, and maintained by serial passage in the peritoneal cavities of BDF1 mice. This and another 5-FU-resistant cell line (L1210/5-FU-2) showed approximately 50-fold increase in resistance to 5-FU, i.e., IC50 of 5-FU determined for wild type L1210 cells was 3 x 10(-7) M, whereas those for 5-FU-resistant lines, L1210/5-FU-1 and L1210/5-FU-2 were 1.65 x 10(-5) M and 1.35 x 10(-5) M, respectively. The incorporation of 3H-5-FU into L1210/5-FU-1 cells was about 57% of that observed in wild type L1210 cells. Northern blot analysis of DHFR mRNA obtained from 5-FU-sensitive and -resistant cell lines revealed four distinct bands of 1.6 kb, 1.2 kb, 1.0 kb and 0.75 kb in length. Although all these bands showed higher density in autoradiography in 5-FU-resistant lines than in wild type, no extra band was observed. Southern blot analysis of DHFR DNA, digested with the restriction enzymes, EcoRI, BamHI or HindIII, revealed no rearrangement. However, all the fragments were expanded, showing that DHFR gene increased in 5-FU-resistant cells. The karyotype analysis carried out for L1210/5-FU-1 showed abnormal banding region in a part of chromosome X, and this chromosomal aberration was considered to be the reflection of the amplification of DHFR gene. Many investigators have reported that thymidylate synthetase (TS), a target enzyme for 5-FU, increased in 5-FU-resistant cells and that the increase of TS was responsible for the drug resistance to 5-FU. The increase both in DHFR mRNA and DHFR DNA suggested the increase in DHFR and also in N5, N10 methylenetetrahydrofolate (methylene THF), a coenzyme of TS. The increase of methylene THF, together with the increase of TS, might result in the resistance of the cells to 5-FU.

Animals↗
PubMed1990

[Subsets of peripheral blood lymphocytes and tumor infiltrating lymphocytes in cancer patients received chemotherapy].

Forty-three patients with advanced cancer were evaluated for the changes of absolute counts of peripheral blood lymphocytes and lymphocyte subsets during chemotherapy or chemoimmunotherapy. In 27 patients who did not respond to the therapy, whole lymphocytes, T cells, helper/inducer T cells and NK cells decreased significantly in number. In contrast, they showed little decrease in 16 cases responded to the therapy. In situ immunohistochemical analysis of the tumor infiltrating lymphocytes was performed on the carcinoma tissues obtained from 25 gastric cancer patients. T cell infiltration, in which helper/inducer T cells were predominant over suppressor/cytotoxic T cells, and NK cell infiltration were found in most of the tissues comprised various carcinoma types of histology. Furthermore, an analysis of a gastric cancer patient treated with systemic administration of 3 BRMs and intratumoral injection of OK-432 indicated that infiltration of cytotoxic T cells and NK cells augmented by cytokines such as IFN-gamma produced from activated helper/inducer T cells and NK cells. Therefore, it is suggested that movements of helper/inducer T cells and NK cells relate to the response to chemotherapy and participate in prognosis of advanced cancer patients.

Adult↗
PubMed1990

[DNA damage and anticancer effect].

In a sense, cancer chemotherapy is similar to antibacterial chemotherapy. The main target for both chemotherapies is on DNA and its precursors. Whenever anticancer drugs exhibit its activity on cancer cells, damage or metabolic abnormality of DNA is usually accompanied. Among various anticancer drugs, the main cellular target of alkylating agents or anticancer antibiotics is DNA strand, and many of newly introduced anticancer drugs exert effect on DNA strand or DNA synthesis. The mechanism of action of quinocarmycin, KT 6149, which is a derivative of mitomycin C, YM534, which shows thrombocyte agglutination activity, and MCNU, a nitrosourea, were studied for their antitumor action and damage to DNA strand. It was found that there was a close relationship between anticancer effect and single strand scission of DNA in all the agents tested.

Animals↗
PubMed1989

[In vivo antitumor activity of mitoxantrone and the flow cytometric analysis of its influence on cell cycle transition--comparison with doxorubicin and aclarubicin on ascitic hepatoma AH109A cells].

Mitoxantrone was compared with doxorubicin and aclarubicin of its in vivo antitumor activity and influence on cell cycle transition by use of rat ascitic hepatoma AH109A. Antitumor activity determined by the cell growth curve was similar in mitoxantrone and doxorubicin, but the sensitivity of AH109A to aclarubicin was lower than that to the other two drugs. Doxorubicin and mitoxantrone showed all phase arrests with 1/10 of maximally tolerated dose (MTD), and with lower concentrations a strong arrest at G2 phase was observed, thus, mitoxantrone appeared to have a similar antitumor activity on AH109A to that of doxorubicin. Aclarubicin, with 1/10 MTD, demonstrated only a transient arrest at G2 phase, cells arrested at G2 phase entering into the next phase. With below 1/10 MTD, there was no appearance on histograms, and the influence on AH109A cell cycle transition by aclarubicin was considered to be little in comparison with doxorubicin and mitoxantrone.

Aclarubicin↗
PubMed1989

Damage to DNA strand and the effects of anticancer drugs.

Cancer chemotherapy is, in a sense, similar to the treatment of infectious disease with antibiotics. The main mechanism of action is on DNA and its precursor, and in the process that anticancer drugs exert the effect on cancer cells, the cells always have abnormal metabolism or destruction of DNA. The main cellular target of most alkylating agents, or anticancer antibiotics is DNA, however, among the anticancer drug newly synthesized, there are some compounds which exert the action on DNA. Quinocarmycin, KT6149, which is a derivative of MMC, YM534, which possesses a platelet agglutinating activity, and MCNU, a nitrosourea compound were studied on the anticancer activity and on damage to DNA strand, and it was found that the lethal effect was deeply concerned with single strand scission of DNA.

Antineoplastic Agents↗
PubMed1989

Mechanism of action of the synthetic imidazole compound YM 534 on human promyelocytic leukemia line HL-60 cells.

The effects of a novel anti-cancer drug, YM 534 on human promyelocytic leukemia line HL-60 cells were investigated. The growth of the cells was completely inhibited with an IC50 of 2.5 X 10(-6) M. The incorporation of 3H-thymidine or 3H-uridine into acid insoluble fraction of the cells was completely inhibited at a 10(-4) M concentration of the drug. However, that of 3H-leucine was suppressed by only 32% at this drug concentration. The single strand scission of DNA of the cells as revealed by alkali sucrose density gradient centrifugation was induced by YM 534 at a 10(-4)M concentration for 60 min. When PM2 DNA in a cell-free system was examined in the presence or absence of reducing agent, no damage to DNA was observed at a 10(-4)M YM 534. The processing of preribosomal to ribosomal RNA of HL-60 cells was retarded at a 10(-5) M level of the drug.

Antineoplastic Agents↗
PubMed1988

Inhibitory effects of prostaglandin A2 on c-myc expression and cell cycle progression in human leukemia cell line HL-60.

The effect of prostaglandin A2 (PGA2) on c-myc expression was investigated in a human promyelocytic leukemia cell line, HL-60, which responded to PGA2 with a dose-dependent growth inhibition. Northern blot analysis indicated that treatment with PGA2 at 0.5 to 5.0 micrograms/ml remarkably reduced the steady state level of c-myc mRNA within 3 h, and then it gradually recovered according to the order of concentration of the drug. In contrast to c-myc, the level of class I HLA mRNA, as an internal control, was not diminished by PGA2 treatment. Further, this reduction of c-myc was not disturbed by cycloheximide, suggesting that this PGA2 action on c-myc expression is independent of de novo protein synthesis. Cytofluorometric analysis revealed that the exposure of HL-60 cells to PGA2 at 0.5 or 5.0 micrograms/ml arrested the cells in the G0-G1 phase of the cell cycle. This accumulation of the cells in G0-G1 phase continues until 24 or 36 h at 0.5 or 5.0 micrograms/ml, respectively. The G0-G1 arrest of the cell cycle was also recovered as the inhibition of c-myc was released. This recovery may be due to the loss of activity of PGA2 in culture medium. This study clearly showed that PGA2 treatment arrested HL-60 cells in the G0-G1 phase of the cell cycle and was associated with the reduction of c-myc mRNA.

Cell Cycle↗
PubMed1988

The mechanism of action of quinocarmycin citrate (KW 2152) on mouse L1210 cells in vitro.

The effects of the antitumor antibiotic, quinocarmycin citrate (KW 2152), on L1210 cells were studied in vitro. The cellular growth was completely inhibited at 10(-6) M KW 2152, and after 2 days no viable cell was seen. The incorporation of 3H-thymidine, 3H-uridine, or 3H-leucine into the acid-insoluble fraction was not affected at 10(-4) M for 1 h; however, when the cells were treated with 10(-6) M for 24 h, the radioactivity appearing in the acid-insoluble fraction was reduced to 20%, 30%, and 48%, respectively, of the control. The single strand scission of the DNA of L1210 cells was seen at 10(-7) M for 24 h, as revealed by an alkaline, sucrose density gradient. However, no damage to plasmid pBR322 was observed even at 10(-6) M KW 2152 for 24 h, as revealed by 0.8% agarose gel electrophoresis, indicating that some soluble factors of the cells might contribute to the damage to the DNA of L1210 cells. The processing of pre-rRNA of the cells was not inhibited at 10(-6) M of the drug for 24 h of incubation.

Animals↗
PubMed1988

Responsiveness of peripheral blood lymphocytes from cancer patients and healthy donors to interleukin-2 (IL-2).

The proliferative response of the peripheral mononuclear cells (MNC) from cancer patients and healthy individuals to IL-2 was studied by use of the quantitative microwell assay of the 3H-TdR incorporation into the cells in vitro. After the addition of phytohemagglutinin (PHA), MNC acquired the reactivity to IL-2 within 3 hr, and reached a maximum after 12 to 17 hr of incubation. Although the IL-2 response of PHA-activated MNC from cancer patient was lower than that from healthy donor, there was no significant difference in the kinetics of proliferation. The maximum response of PHA-activated MNC from both cancer patients and healthy donors to IL-2 was observed at 96 hr and 84 hr, respectively. When monocytes were removed from MNC, IL-2-associated growth of the remaining fraction of MNC was decreased to 40-70% in both cancer patients and healthy donors. Furthermore, monocytes from cancer patients did not affect the IL-2 responsiveness of lymphocytes from healthy donors, and vice versa. The number of T lymphocytes having IL-2 receptors (IL-2R) from cancer patients was lower than that from healthy donors. These facts indicated that the lower IL-2 response of MNC from cancer bearer was due to the decreased number of T lymphocytes possessing IL-2R, and not due to monocytes themselves.

Adult↗
PubMed1988

[Mechanism of action of anti-cancer drugs from the viewpoint of RNA metabolism].

The mechanism of action of anti-cancer drugs, especially 5-FU, was discussed on the basis of RNA metabolism. After its incorporation into cells, 5-FU is metabolized through the uracil pathway, and finally incorporated into various species of RNA. On the other hand, 5-FU metabolized to FdUMP forms a covalent ternary complex among TS and mTHF, and inhibits de novo TMP synthesis, resulting in the inhibition of DNA synthesis. However, 5-FU was found to exert an effect on TS- mutant FM3A cells which was almost as lethal as the effect on wild-type FM3A cells in the presence of thymidine. Therefore, this lethal effect could be attributable to the inhibition of RNA metabolism, rather than DNA metabolism. The effects of 5-FU on RNA metabolism in L1210 cells are as follows: (1) inhibition of the processing of preribosomal RNA to ribosomal RNA (2) inhibition of the synthesis of poly(A) RNA of mRNA (3) inhibition of tRNA methylation (4) impaired synthesis of snRNA, U4, U6. (5) inhibition of pre-rRNA methylation (6) enhancement of poly(A) RNA translation. With reference to the items listed above, a discussion was made on the basis of our experimental results.

Animals↗
PubMed1987

Pharmacokinetic studies on 1-(2-chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea (TA-077). III. Pharmacokinetics of a new nitrosourea antitumor agent TA-077 in humans (a phase I study).

A new nitrosourea antitumor agent TA-077, 1-(2-chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea, was intravenously administered to 15 cancer patients at doses ranging from 7 to 100 N (1 N = 30 mg/m2) in a phase I clinical trial. Time courses of blood concentrations of TA-077 and its active metabolite TA-G, 3-beta-D-glucopyranosyl analog of TA-077, were followed. The TA-G concentration reached a maximum at 7.0 +/- 2.3 min, and decreased thereafter with a half-life of 12.9 +/- 2.8 min. The time-course patterns and various pharmacokinetic parameters of TA-077 and TA-G were similar to those in the guinea pig, which, like humans, lacks plasma maltase activity. The 2 h-urinary excretion rate of TA-G in the above patients ranged from 0.15 to 7.7% of the dose. The areas under the concentration-time curve and maximal concentration values were both linearly correlated to the dose with correlation coefficients of 0.78 and 0.82, respectively. Repeated administration of TA-077 (29 to 40 N) for 5 or 6 consecutive days did not affect the pharmacokinetic parameters of TA-077 and TA-G in 7 cancer patients except for slight increases in the half-life and area under the curve of blood TA-G.

Adult↗
PubMed1987

[A case of multiple myeloma responding very well to the combination of K18 with prednisolone].

A case of multiple myeloma refractory to various anticancer drugs was effectively treated with the combination of K 18 with prednisolone, which led to a remarkable decrease of serum M-protein and overall recovery. In 8 months of the treatment, although slight bone marrow suppression was noted, no severe side effect was observed. The patient has survived for more than one year in remission. We suggest that the combination of K18 with prednisolone may be effective for multiple myeloma which is unresponsive to treatment with anticancer drugs.

Drug Combinations↗
PubMed1987

[The metabolism of high-molecular-weight substances in cells and the effect of anticancer drugs].

The term "high molecular weight substances" used in this paper implies mostly nucleic acids of certain molecular weight and protein, and the genetic aspects of anti-cancer chemotherapy were discussed. Studies on the mechanism of action of 5-FU have been focused on the inhibition of DNA synthesis, and it has been reported that 5-FU inhibits the growth of thymidylate synthesis deleted FM3A Thy 21 cells even in the presence of thymidine, and that the level of TTP is equal to that in control cells. On the other hand, the active metabolite of 5-FU, FdUMP, is known to bind to synthesized thymidylate and 5, 10-methylene-tetrahydrofolic acid to form a ternary complex. Recently, the cytocidal effect of 5-FU was observed in thymidylate synthetase-deficient cells in the presence of a sufficient amount of thymidine, suggesting that the cytocidal effect of 5-FU might be caused by inhibition of the RNA pathway. In this laboratory, the effect of 5-FU on polysomal patterns and the incorporation of 3H-UR into polysomes was studied in L1210 cells, but no significant difference was observed between normal and 5-FU-treated cells. Ribosomal RNA extracted from the polysomes of 5-FU treated cells appeared to contain a smaller 28S rRNA in comparison to 18S rRNA, indicating that the processing might be inhibited. Expression of mouse H-2Dd mRNA was not influenced by 5-FU at 10(-5) M up to 6 h. Methotrexate (MTX) has a chemical structure similar to folic acid, and is known to bind to DHFR (dihydrofolate reductase), and inhibit the synthesis of TMP. The cellular PRPP content is known to be increased by MTX, which inhibits purine synthesis. The level of PRPP content was found to be increased approximately 25 fold at 3 h after 10(-6) M MTX although normal bone marrow cells showed no increase even after MTX. This increased level of PRPP thus obtained in cancer cells was thought to be used for the phosphorylation of 5-FU. Clinically, sequential chemotherapy using MTX and 5-FU was employed successfully for solid tumors on the basis of the experimental evidence. In order to minimize the adverse effects of anti-cancer drugs, a technique involving the incorporation of the drug-resistant gene into normal bone marrow cells has been designed in this laboratory, and the MTX-resistant cells thus obtained are transplanted into the tumor-bearing mice.

Animals↗
PubMed1987

[Sequential methotrexate-5-fluorouracil (MTX-5-FU) treatment of patients with advanced gastric and colorectal cancer. Sequential Methotrexate-5-FU Study Group].

A multicenter cooperative study was conducted from July 1984 to March 1986 to evaluate the clinical efficacy of sequential MTX-5-FU treatment in 96 cases of advanced gastric cancer and 39 cases of colorectal cancer. 5-FU 600 mg/m2 i.v. was given and MTX 30 mg/m2 (A), 100 mg/m2 (B) and 300 mg/m2 (C) i.v. were given, and the administration interval between MTX and 5-FU was 1 to 3 h for the gastric cancer group, and 7 h for the colorectal cancer group. Leucovorin rescue of 10 mg/m2 p.o. was given 24 h after MTX administration. In the gastric cancer group, the response rate for Regimen A was 23.2% (CR 1 and PR 12) out of 56 evaluable cases, and for Regimen B, 40.5% (CR 1 and PR 14) out of 37 evaluable cases. In the colorectal cancer group, the response rate for Regimen A was 28.6% (PR 6) out of 21 evaluable cases and for Regimen B, 20.0% (PR 3) out of 15 cases. Median survival time for the gastric cancer group was 5.5 months with Regimen A and 7.6 months with Regimen B, and for the colorectal cancer group 10.9 months with Regimen A and 7.9 months with Regimen B. Main adverse effects were marrow impairment and gastrointestinal symptoms such as nausea, diarrhea, and stomatitis. In this study Regimen B showed relatively good results. In order to evaluate the biochemical modulation occurring with sequential MTX-5-FU treatment, a further phase III study in gastric cancer patients should be conducted.

Adult↗
PubMed1986

The inhibitory effects of 5-fluorouracil on the metabolism of preribosomal and ribosomal RNA in L-1210 cells in vitro.

Addition of 5FU to the culture medium of mouse L-1210 cells resulted in inhibition of the maturation process of ribosomal RNA precursors in vitro. In the presence of 10(-6) M 5FU for 2 h, the 45S preribosomal RNA was processed to 32S preribosomal RNA, but 28S rRNA was not produced. The processing to 18S rRNA was intact at this drug concentration. Higher concentrations of 5FU for a longer incubation period affected the RNA processing more severely. At 10(-5) M of the drug for 24 h the processing to 28S rRNA and 32S preribosomal RNA. When the cells were labeled with 14C-UR for 2 h following 3H-5FU at 10(-6) M for 24 h, the radioactivities of newly synthesized RNA labeled with 14C-UR accumulated in the region of 45S and 32S preribosomal RNA, and no processing to 28S rRNA was observed. Radioactivity corresponding to 3H-5FU did not persist in the preribosomal RNA region, because further maturation proceeded in the condition of depletion of 5FU after the long incubation period. Thus, inhibition of the processing of preribosomal RNA to 28S rRNA was not brought about by the accumulation of 5FU-substituted 45S preribosomal RNA, but by some other, yet unknown, mechanism.

Animals↗