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[Successful chemotherapy in postoperative brain metastasis of breast cancer using ACNU--two case reports].

Two cases of postoperative brain metastasis of breast cancer were evaluated after chemotherapy using ACNU. Case 1: A 47-year-old female, who had undergone right standard radical mastectomy in 1979 for breast cancer (T2 N0M0, papillo-tubular carcinoma), was treated with ADM, TAM, and 60Co irradiation for bone metastasis in 1983. In 1984, she complained of loss of consciousness and paralysis of the extremities due to brain metastasis. After chemotherapy using ACNU (100 mg X 3), brain metastasis could not be detected on CT. She remained asymptomatic for more than 9 months without recurrence after therapy. Case 2: A 46-year-old-female, who had undergone left standard radical mastectomy in 1980 for breast cancer (T1 N1 M0, medullar tubular carcinoma), complained of headache and vertigo accompanying a hard tumor in the scalp. Chest X-ray and CT demonstrated right lung metastasis and left cerebellar metastasis. After combination chemotherapy using ACNU (100 mg) + MMC (4 mg) i.v. and FT (600 mg/day) p.o., symptoms and tumor on CT disappeared for 10 months after therapy. However, the patient died of aggravation of angina pectoris and D.M. from which she had been suffering for several years previously. These two cases correspond to complete response (CR) according to the response criteria proposed by Koyama-Saitoh.

Antineoplastic Agents↗

[Overcoming of ACNU resistance in a subline of rat glioma in vitro and in vivo by reserpine].

Reserpine was shown to enhance the cytotoxicity of ACNU in both C6 and C6/ACNU rat glioma cells in vitro and also to enhance the chemotherapeutic effect of ACNU in C6/ACNU-bearing rats (C6/ACNU meningeal gliomatosis rats), in which ACNU resistance could be partially overcome by reserpine. When reserpine was added to the culture at a concentration of 10 microM, the IC50 of ACNU for C6/ACNU cells decreased to the level of that for C6 cells. Intracellular uptake of ACNU in C6/ACNU cells increased and the efflux from the cells decreased when 20 microM reserpine was added to the culture. In in vivo experiments, combined ACNU (1 mg/kg) and reserpine (250 micrograms/kg) therapy by intrathecal injection of these drugs improved % ILS (increased life span) with statistical significance compared with that after treatment with ACNU alone. The probable explanation of the enhanced cytotoxic-effect of ACNU in ACNU-resistant glioma cells presented in in vitro and in vivo is increased intracellular ACNU concentration resulting from inhibition of the efflux of ACNU from the resistant cells.

Animals↗

[Chemotherapy of renal cell carcinoma. 2. Combined chemotherapy using ACNU and VBL].

Nineteen patients with renal cell carcinoma who had undergone radical nephrectomy have been treated with a combination of chemotherapy and partly hormonal therapy using ACNU, vinblastine and chloromadinone acetate. The efficacy of the combination therapy in advanced renal cell carcinoma was studied and only one out of nineteen cases having lung and pleural metastasis shows no change lasting from one to eighteen months. The prophylactic efficacy was studied in eighteen patients with stage I to IVA renal cell carcinoma (contained one patient with stage IVA renal cell carcinoma who had undergone radical nephrectomy and coecum resection for coecum invasion). Tumor recurrence occurred in 5 cases, that is 5 cases within 1 year and 1 case within 2 years. The combination of chemotherapy using ACNU & vinblastine must be used carefully for severe side effects.

Adult↗

[Mechanism and overcoming of resistance in ACNU-resistant sublines of rat brain tumors].

One of the most serious problems in chemotherapy of brain tumors is that tumor cells are able to acquire resistance to initially effective cytotoxic agents. In order to study the mechanism of such resistance to ACNU and the means to overcome it, two variant cell lines (C6/ACNU and 9L/ACNU) resistant to ACNU were selected in vivo. Uptake and retention of ACNU in these resistant cells were studied with [14C] ACNU. The results indicated that the resistance exhibited by both sublines of C6/ACNU and 9L/ACNU were due to both reduced uptake and retention of the drug. In an attempt to clarify the more detailed biochemical mechanism of resistance in these cells, we surveyed various membrane-modifying agents which potentiate the sensitivity of these resistant cells to ACNU. Among a number of membrane-modifying agents, calcium antagonists, especially nicardipine and verapamil, were found to cause retention of ACNU in the resistant cells and to enhance the effect of ACNU on these resistant cell lines. It might therefore be concluded that ACNU resistance can be overcome by membrane-modifying agents, such as nicardipine and verapamil.

Animals↗

[Experimental studies on induced hypertension chemotherapy of intracerebral inoculated gliomas in rats].

Blood flow of transplanted intracerebral rat gliomas was measured before and after a constant I.V. infusion of angiotensin II-induced arterial hypertension using hydrogen clearance method. The brain tumor model was produced in syngeneic Wistar-King-Aptekman male rats by stereotaxic inoculation of ethylnitrosourea-induced glioma cells (KEG-1). Induced hypertension by angiotensin II infusion resulted in a significant increase in tumor blood flow compared with control levels (P less than 0.001). In addition, the therapeutic effect of administration of 3-[(4-amino-2-methyl-5-pyrimidinyl) ethyl] -1-(2-chloroethyl)-1-nitrosourea (ACNU) during angiotensin II-induced hypertension was evaluated. At 12 days after implantation, tumor-bearing rats were administrated angiotensin II as the mean blood pressure reached 150 mmHg, followed by ACNU injection, maintained the same blood pressure for 20 minutes. ACNU with induced hypertension group showed a median survival time of 27.0 days, which was significantly (P less than 0.02) longer than that of ACNU alone (22.0 days). It is therefore suggested that chemotherapy with angiotensin II-induced hypertension has a enhancing effect on chemotherapy for improving the drug delivery to tumor tissue by a increased tumor blood flow.

Angiotensin II↗

[The effect of hyperthermia and antitumor drugs on brain tumor cell lines].

The effects of heat and antitumor drugs on malignant brain tumor cell lines were studied. A human glioblastoma cell line (SKMG1) and rat malignant brain tumor cell lines (T9, EB 679 and TR 481) were used in this experiment. Five different modalities of treatment with heat and drugs were used as follows: (Group 1) exposure to heat alone at 42 degrees C for one hour; (Group 2) exposure to antitumor drug alone for one hour (ACNU 2.5 or 5 micrograms/ml, ACR 0.02 micrograms/ml and CDDP 1 microgram/ml); (Group 3) simultaneous exposure to heat at 42 degrees C and drug for one hour; (Group 4) heat at 42 degrees C given first for one hour, followed by one hour exposure to drug one hour later ("preheating"); (Group 5) drug given first for one hour, followed by one hour exposure to heat at 42 degrees C one hour later ("postheating"). After each treatment, the inhibition rate at 4 days was evaluated and compared for each group. A synergistic effect was observed in Group 3. For example, when T9 cells were exposed to ACNU and to heat at 42 degrees C at the same time for one hour, inhibition rate was 78%, while the rates for Group 1 and Group 2 were 7% and 21%, respectively. The cytotoxicity of simultaneous treatment with antitumor drugs (ACNU, ACR and CDDP) and hyperthermia at 42 degrees C was apparently superior to that of other treatment modalities.

Aclarubicin↗

[A chemotherapy regimen including CDDP in patients with bronchogenic carcinoma--a comparison between bronchial artery infusion and intravenous administration].

Forty patients with lung cancer were treated using two methods. One was transbronchial artery infusion (BAI) of CDDP and the other was intravenous administration of CDDP with VDS, ACNU or etoposide. There was no difference in response rate between the two groups. The response rate was higher in patients with squamous cell carcinoma compared to these with adenocarcinoma. Compared with the combination group, BAI patients had fewer adverse effects, such as myelosuppression, alopecia, nausea and vomiting. Thus, it was concluded that CDDP is very effective for patients with lung cancer and that CDDP administered by BAI is useful for hilar-type squamous cell carcinoma.

Aged↗

[Studies on the mechanism of ACNU resistance in sublines of rat C6 glioma and 9L gliosarcoma in vitro].

One of the serious problems in chemotherapy of brain tumors is that tumor cells are able to acquire resistance to initially effective cytotoxic agents. In order to study the mechanism of this resistance against chemotherapeutic agents, especially ACNU, two variant cell lines (C6/ACNU and 9L/ACNU) resistant to ACNU [1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride] were selected previously in vivo from rat C6 glioma and 9L gliosarcoma, respectively. Uptake and retention of ACNU in these resistant cells were studied with [14C]ACNU. The result indicated that the resistance exhibited by both sublines of C6/ACNU and 9L/ACNU cells were due to the reduced uptake and retention of the drug. The study of the effects of oxidative phosphorylation inhibitor, DNP (2, 4-dinitrophenol), on the uptake and retention of ACNU suggested that there is an active outward transport mechanism for ACNU in 9L/ACNU cells. It might be concluded that ACNU-resistant brain tumor cells are resistant to ACNU by virtue of both the reduced uptake of the drug and the increased active efflux.

Animals↗

[Possibility of overcoming of ACNU resistance in an ACNU-resistant subline of C6 rat glioma].

Membrane-modifying agents such as reserpine, calcium antagonists (nicardipine, verapamil) and calmodulin inhibitor (trifluoperazine) were found to enhance the cytotoxicity of ACNU in vitro and in vivo in ACNU-resistant C 6 (C 6/ACNU) glioma. In in vitro experiments, uptake and retention studies with [14C] ACNU revealed that intracellular uptake and retention of ACNU in C 6 cells were larger than those in C 6/ACNU cells, and that these membrane-modifying agents increased the cellular uptake and retention of ACNU in C 6, especially in C 6/ACNU cells. The amount of ACNU in C 6/ACNU cells reached the same level as that detected in C 6/ACNU cells. When these drugs were added along with ACNU at the concentration of 10 to 20 microM to the culture in vitro, ACNU resistance was completely overcome. In in vivo experiment, reserpine, nicardipine, verapamil and trifluoperazine in doses 250 to 500 micrograms/kg intrathecally administered with 1 mg/kg ACNU 1 day after the tumor inoculation significantly enhanced the chemotherapeutic effect of ACNU in C 6/ACNU bearing (C 6/ACNU-MG) rats. It might be concluded that the mechanism of enhancement of ACNU cytotoxicity presented in in vitro and in vivo is explained by the enhanced accumulation of ACNU by these membrane-modifying agents in C 6, especially in ACNU-resistant (C 6/ACNU) cells, and, furthermore, that combination chemotherapy with ACNU and such membrane interacting drugs as reserpine, calcium antagonists (nicardipine, verapamil) and calmodulin inhibitor (trifluoperazine) could lead to the capability of overcoming resistance to ACNU in glioma.

Animals↗

Cellular resistance to chloroethylnitrosoureas, nitrogen mustard, and cis-diamminedichloroplatinum(II) in human glial-derived cell lines.

We investigated the cytotoxic and cytogenetic effects of 3-(4-amino-2-methyl-5-pyrimidinyl)methyl-1-(2-chloroethyl)-1-nitrosourea and 1,3-bis(2-chloroethyl)-1-nitrosourea on five cell lines established from human glioma biopsy specimens. Compared to the sensitive cell line SF-126, SF-188 cells are 3- to 6.5-fold more resistant to the cytotoxic effects and 8- to 14-fold more resistant to the induction of sister chromatid exchanges. Cytotoxic effects and induction of sister chromatid exchanges are intermediate for SF-210 and SF-295 cell lines compared with SF-126 and SF-188. There is a good correlation between susceptibility to the cytotoxic effects and formation of DNA interstrand cross-links for cells treated with 3-(4-amino-2-methyl-5-pyrimidinyl)methyl-1-(2-chloroethyl)-1-nitrosourea . We quantitated the extent of repair of O6-methylguanine after treatment of these cell lines with [3H]methylnitrosourea. SF-126 cells showed no detectable repair of O6-methylguanine, SF-210 and SF-295 had intermediate levels of repair, and SF-188 had very high levels of repair. We conclude that the cellular capacity to repair O6-chloroethylguanine adducts in DNA, which is reflected in the methyl repair process, is an important factor in determining cytotoxic response, and that increased repair of O6-chloroethylguanine decreases cytotoxicity and causes fewer sister chromatid exchanges and DNA interstrand cross-links to form in cells treated with chloroethylnitrosoureas. We studied the effects of cis-diamminedichloroplatinum(II) and nitrogen mustard in these cell lines. cis-Diamminedichloroplatinum(II) was equally cytotoxic and induced the same number of sister chromatid exchanges and DNA interstrand cross-links in all five cell lines. In contrast to the results obtained by treatment with chloroethylnitrosoureas, SF-126 cells treated with nitrogen mustard are 7.6-fold more resistant to the cytotoxic effects, 2-fold more resistant to the induction of sister chromatid exchanges, and 3-fold more resistant to the induction of DNA interstrand cross-links than are SF-188 cells. The results of this investigation with five human glial-derived cell lines clearly indicate that the molecular mechanisms of cellular resistance to alkylating chemotherapeutic agents are highly specific. Cellular resistance to chloroethylnitrosoureas does not result in cross-resistance to nitrogen mustard or cis-diamminedichloroplatinum(II).

Carmustine↗

Distribution of radiolabeled 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitros ourea hydrochloride in rat brain tumor: intraarterial versus intravenous administration.

To assess the rationale of intraarterial (i.a.) 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea chemotherapy, distribution of 14C-labeled 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)- 3-nitrosourea in rat glioma was studied after i.a. or i.v. infusion. Immediately after infusion, the tumor located in the hemisphere of intracarotid infusion received 4.6-fold higher radioactivity than the tumor located contralaterally to intracarotid infusion and 2.8-fold higher radioactivity than i.v. infusion. The difference was kept up to 30 min after i.a. infusion. Autoradiographic observation indicated rather uniform distribution of the tracer in the central portion of i.a. infusion. However, in the periphery of i.a. infusion, distribution of the tracer was nonhomogenous. The results indicate that i.a. 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea chemotherapy is useful when the tumor has high blood flow and is located in the center of an infused area.

Animals↗

[Possibility of overcoming ACNU resistance in ACNU-resistant sublines of rat brain tumors in vitro by a calmodulin inhibitor].

A calmodulin inhibitor, trifluoperazine, was found to enhance the cytotoxicity of ACNU in vitro in rat C6 glioma, 9L gliosarcoma and their ACNU-resistant sublines (C6/ACNU and 9L/ACNU). Uptake and retention of ACNU in these cells were studied with [14C]ACNU in the absence or presence of trifluoperazine. The results indicated that intracellular uptake and retention of ACNU in C6 and 9L cells were larger than those in C6/ACNU and 9L/ACNU cells, and that trifluoperazine increased the cellular uptake and retention of ACNU in C6 and 9L, especially in C6/ACNU and 9L/ACNU cells. The amounts of ACNU in C6/ACNU and 9L/ACNU cells reached almost the same level as those detected in C6 and 9L cells. When trifluoperazine were added along with ACNU to the culture in vitro at a concentration of 10 and 20 microM, ACNU resistance was completely overcome. Furthermore, treatment of C6 and C6/ACNU cells with 20 microM trifluoperazine did not change the cellular uptake rate of [14C]AIB (alpha-aminoisobutyric acid), which might indicate that the membrane permeability of the cells was kept intact during the drug treatment. The same phenomenon was observed in 9L and 9L/ACNU cells. It might be concluded that the enhanced effect of cytotoxicity of ACNU in ACNU-resistant rat brain tumor cells presented in this study is presumably due to the increase of intracellular concentration of ACNU resulting from the inhibition of the efflux of ACNU by trifluoperazine from the resistant cells. It was also suggested that ACNU resistance in malignant brain tumors could be overcome by combination chemotherapy with ACNU and calmodulin inhibitors.

Animals↗

[Anticancer drug induced sister chromatid exchange and correlation to cell survival in human brain tumor cells].

Sister chromatid exchanges (SCEs) induced by four anticancer drugs, 3-(4-amino-2-methyl-5-pyrimidyl) methyl-1-(2-chloroethyl)-1-nitrosourea (ACNU), 1-3-bis (2-chloroethyl)-1-nitrosourea (BCNU), nitrogen mustard (HN2), cis-diamminedichloroplatinum (II) (cis-Pt) were examined on five cell lines derived from human malignant glioma biopsy specimens, and compared to results obtained with colony-forming efficiency (CFE) assay. Treatment of the five cell lines with these four drugs produced concentration-dependent increases in SCEs. Treatment with ACNU induced the most SCEs in SF-126 cells decreasing in SF-268 cells followed by SF-210 cells, SF-295 cells, and the least SCEs in SF-188 cells. The results of the SCE assay with BCNU in these cell lines were similar with ones with ACNU. In contrast to results obtained with nitrosoureas, the most SCEs were induced in SF-188 cells and the least were induced in SF-126 cells by the treatment of HN2. The frequency of SCEs induced with cis-Pt was almost similar in the five cell lines. The number of SCEs induced by the treatment of ACNU, BCNU, HN2 and cis-Pt in five cells lines showed a good correlation with cytotoxicity measured by CFE assays, and induction of SCEs occurred at much lower concentrations of these anticancer drugs than those required to induced cell kill. These results suggest that measurement of induced SCEs in human brain tumor cells treated with some anticancer drugs provide a more sensitive indicator of drug action than CFE assay and that SCE assays may be a useful method of the in vitro sensitivity test to some anticancer drugs.

Antineoplastic Agents↗

[Distribution of ACNU in the rat brain after intracisternal injection--macroscopical autoradiographic study].

In the previous reports, we demonstrated that intracisternal ACNU is effective in prolonging the survival time of rats with meningeal carcinomatosis induced by intracisternal inoculation of Walker 256 carcinosarcoma cells, and systemic and local toxicity can be avoided by adjusting the drug dose. In this experiment, we studied distribution of 14C-ACNU in the rat brain after intracisternal administration using a macroscopical autoradiographic method. One muCi of ethylene-14C-ACNU was percutaneously injected into the cisterna magna of normal female Wistar rats weighing approximately 150 g. The animals were sacrificed 5 and 30 minutes, and 3 hours after injection (3 animals in each group). The brain was quickly removed and frozen in Freon. 14C-ACNU autoradiograms were made in coronal sections of the brain, which were cut in 20 mu thick and exposed to the film for 7 days. In 5 minutes after administration, high radioactivity was distributed in the subarachnoid space of the basal and ambient cisterns and hypocampal fissures, and subpial brain tissue up to 1 or 2 mm in depth. High radioactivity was also present in the ventricles and subependymal layer. In 30 minutes after administration, total radioactivity has already reduced in amount, however, local distribution has not changed so much as compared to that of 5 minutes after injection. No radioactivity was observed in the deeper part of the brain. In 3 hours after administration, only a small amount of radioactivity remained in the subarachnoid space and subpial region.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗