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At least 469 records · Page 26Linked to original sources
PubMed1998

Sensitization of acnu killing effects on HeLa S3 cells by MGMT antisense RNA transfection.

O6-methylguanine-DNA-methyltransferase (MGMT) plays a very important role in the cellular resistance to nitrosoureas drugs. Inhibition of MGMT might be a useful approach in tumor chemotherapy. In this study, the depletion of MGMT activity by retroviral-mediated antisense RNA transfection were reported. Three retroviral vectors expressing MGMT antisense RNA were constructed and transfected into HeLa S3 cells. The difference of MGMT mRNA, MGMT activity as well as cellular resistance to ACNU before and after transfection were observed. It was found that antisense RNA targeting 5' region and whole length of MGMT mRNA could partially deplete MGMT activity and enhance killing effects of ACNU. However, 3' region antisense RNA had no effect on MGMT modulation.

Antineoplastic Agents↗
PubMed2003

[Malignant melanoma of the alimentary tract].

We reviewed case reports of malignant melanoma in the alimentary tract and discussed the diagnosis and treatment. Cases of malignant melanoma in the alimentary tract have mostly originated from the esophagus and an anorectal lesion. Metastatic tumors occurred mainly in the stomach and the small intestine. Although resection with lymph node dissection was performed, the prognosis of these patients was worse than that of patients with carcinoma. Malignant melanoma of the alimentary tract might be more aggressive than that of the skin. A combined modality treatment including progressive chemotherapy and biotherapy is expected to improve the prognosis of these patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

[A case of spinal cord glioblastoma multiforme].

A 35-year-old woman was admitted to our hospital with a 3 month history of progressive paraparesis and impairment of bowel and bladder function. MRI suggested a malignant glioma at the level of T9 to L1. Laminectomy and subtotal removal of the tumor was performed. The surgical specimen was a glioblastoma multiforme. An aggressive adjuvant therapy was scheduled to prevent rapid local regrowth and leptomeningeal dissemination. Radiotherapy with a total dose of 65Gy was delivered with chemotherapy including ACNU (2mg/kg) and vincristine (0.2mg/kg). Lymphokine-activated killer (LAK) cells were given intrathecally with a total dose of 1.6 x 10(9) LAK cells with 3 x 10(4) units of IL-2. MRI taken 6 months after surgery revealed no residual tumor, and no malignant cell was detected in the patient's CSF. After physiotherapy, she became able to walk with a stick and was discharged. Chemotherapy (ACNU 2mg/kg/8 weeks) had been further continued for 2 years. She did well until 14 months after surgery, when paraparesis recurred and rapidly progressed to completism. MRI revealed a spinal cord swelling with marked edema, suggesting delayed radiation necrosis. Two years after surgery, MRI showed a marked atrophy of the spinal cord, and no residual tumor. But 3 years after surgery, a round tumor at the level of T11 and T12 was revealed on MRI, and she was admitted to our hospital again. A spinal cord amputation was performed, and the tumor was totally removed without worsening her neurological symptoms. Surgical specimen of the tumor was glioblastoma multiforme again.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Intra-arterial chemotherapy with ACNU in the treatment of malignant gliomas].

Twelve patients with supratentorial gliomas were treated with intra-arterial ACNU followed by intravenous maintenance chemotherapy. Six of the patients, treated from February 1987 through May 1989, received doses of 120-200 mg/m2 (high dose treatment group); six patients, treated from June 1989 through October 1990, received doses of 80-100 mg/m2 (low dose treatment group). The drug was given via the supraophthalmic portion of the internal carotid artery or vertebral artery at a rate of 10 mg/min. The response rate (CR + PR) on CT scan was 50% (3/6) in the high dose treatment group and 17% (1/6) in the low dose treatment group. Survival periods from first operation, however, did not differ between the high and low dose treatment groups. Bone marrow suppression was dose-related and reversible at these doses. Severe neurotoxicities (hemiparesis and aphasia) developed in the patients who received 200 mg/m2 of ACNU; in one case, this was irreversible. High dose intra-arterial ACNU chemotherapy is effective in reducing tumor size on CT scan but the prognosis is not improved. The dose limiting factor of intra-arterial nitrosourea is neurotoxicity, and doses of more than 200 mg/m2 are considered to be dangerous.

Adult↗
PubMed1992

[Quantitative analysis of glutathione and glutathione S-transferase in human brain tumors, C6 rat glioma cells and drug resistant C6 cells].

Glutathione (GSH) and Glutathione S-transferase (GST) plays an important role in the protection of cells against damage from free radicals and also influences cytotoxicity to some kinds of chemotherapeutic agents. GST comprises a group of abundant and widely distributed catalytic and binding proteins that facilitate the conjugation of GSH with the electrophilic center of a large spectrum of hydrophilic molecules. Multiple GST isozymes in mammalian tissues arise from dimeric combination of a number of distinct subunits grouped into three major classes: alpha (alpha), mu (mu), and pi (p). We report the total GST, GST-p activity and GSH content of human brain tumors, C6 rat glioma cells and drug resistant C6 cells. The values of total GST activity in 42 normal brain and brain tumors were quantitatively analyzed. Total GST activity was 92.6 +/- 25.1 units (mean +/- standard deviation) in 8 samples of normal brain tissues, 126 +/- 58.8 units in five grade II or III astrocytomas (154 +/- 63.3 units in grade II astrocytomas, 84.4 +/- 2.7 units in 2 grade III astrocytoma), 66.2 +/- 29.3 in 5 glioblastoma cases, 94.7 +/- 47.7 units in 3 metastatic tumors, 302 +/- 114 unit in 8 meningiomas and 213 +/- 90.4 units in 3 neurinomas. Differences of GST activity between glioblastomas and meningiomas, grade II or III astrocytomas and meningioma, in normal brain tissues and meningioma were statistically significant (p < 0.01). The difference between normal brain tissues and benign tumors (meningiomas and neurinomas), gliomas and benign tumors were also statistically significant (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Chemo-sensitivity test for malignant brain tumors by DNA histogram, in vitro].

Application of flow cytometric DNA analysis was tried to determine the sensitivity of ACNU, one of nitrosourea derivatives which had been used very commonly for malignant brain tumors, to tumor cells. To evaluate the degree of chemo-sensitivity of ACNU, factor B was introduced, indicating the accumulated cells in SG2M phases after ACNU treatment as the percentage of cells that was previously in the SG2M phases and it revealed that ACNU sensitive cell clones gave much larger values of Factor B than ACNU resistant ones at the concentration of 10 micrograms/ml ACNU treatments. Twenty clinical materials obtained by operation were examined by measuring the degree of values of this Factor B, and the findings indicated that this method would be applicable as a clinical test for chemo-sensitivity of malignant brain tumors, after some improvement of the method.

Animals↗
PubMed1992

[Primary intracranial melanoma: a case report].

A rare case of primary intracranial melanoma is presented in a 34-year-old man with initial symptoms of persistent headache. In magnetic resonance imaging(MRI), this case had all the characteristic findings of intracranial melanoma which had been reported previously. In 123I-iodoamphetamine-single photon emission CT (123I-IMP-SPECT), abnormal accumulation of 123I-IMP was recognized in early and late phase imaging, which was very specific to the lesion. This is the first report of 123I-IMP-SPECT performed on a primary intracranial melanoma. Tumor mass originated from pia mater was surgically resected, but the dissemination of tumor cells was recognized macroscopically. Pathological examination of the specimen showed very little malignant changes of melanoma cells, which was in contrast to the previous reports. Although, no standard chemotherapy of the primary intracranial melanoma has been established, DAV therapy to the dissemination of tumor cells into the subarachnoid space, and intravenous administration of interferon-beta were performed in this case. Methods of differential diagnosis and treatments of primary intracranial melanoma are reviewed and discussed.

Adult↗
PubMed1992

Expression of O6-methylguanine-DNA methyltransferase and chloroethylnitrosourea resistance of human brain tumors.

Northern blot analysis with O6-methylguanine-DNA methyltransferase (MGMT) cDNA as a probe was used to analyze the MGMT activity regulating drug resistance of human cells to chloroethylnitrosoureas (CENUs). By this method, the expression levels of MGMT mRNA in six human glioma cell lines and 12 human brain tumor tissues from surgical specimens were determined. These MGMT mRNA levels were compared with the SD10 values of the tumor cells, estimated by cell survival assay, which indicated their resistance to the anticancer drug, 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU). Human brain tumors that were highly resistant to ACNU, such as glioblastoma Gbl1 and metastatic brain tumor Col1 with SD10 values (microM) of above 100, expressed markedly increased amounts of 0.95 kb MGMT mRNA. In contrast, tumor cells such as U-87MG, U-251MG, U-343MG, U-373MG and SF-126 with SD10 values of under 14 indicating low resistance to ACNU scarcely synthesized any MGMT mRNA. These results indicated that the level of expression of MGMT mRNA in human brain tumors determined by Northern blot analysis truly reflects their cellular resistance to ACNU. Thus the Northern method with MGMT cDNA probe reported here is a practical and reliable method for estimation of cellular resistance to CENUs such as ACNU and for screening the chemotherapeutic response to CENUs of human brain tumors.

Blotting, Northern↗
PubMed2004

[Study on MGMT assay and tumor individual predictable chemotherapy].

How to predict and surmount the cell resistance in tumor chemotherapy is a prompt problem. We have observed that there were close correlation among O6-Methylguanine-DNA methyltransferase (MGMT) enzyme activity, protein expression and cell resistance to alkylating agents especially to nitrosourea anti-tumor compounds by a series of experiments including cell survival, xenografts in nude mice, tumor patient biopsy and molecule biology assay. We found that those tumors with high MGMT activity and abundance of MGMT protein were resistant to alkylating agents killing effect, while those with low MGMT activity and little MGMT protein were sensitive to alkylating anti-tumor drugs. We proposed a new tactics for tumor predictable chemotherapy treated with alkylating agents based on MGMT protein detection. By means of preparing MGMT monoclone antibody, we have succeeded in developing MGMT immunohistochemistry diagnostic kit.

Alkylating Agents↗
PubMed2005

[Medulloblastoma with mandibular metastasis after complete remission of the central nervous system lesions].

A 6-year-old boy presented with headache and vomiting. Brain and spinal MRI demonstrated a large mass in the cerebellar vermis and 4th ventricle and showed thick spinal subarachnoid dissemination. Suboccipital craniotomy was performed and the tumor was totally removed. The histological diagnosis was medulloblastoma. The patient subsequently received craniospinal irradiation, and also received systemic and intrathecal perfusion chemotherapy. Then complete remission was achieved 10 months after operation. Three years later, however, a swelling at the left mandibular angle appeared. A CT scan revealed osteosclerotic lesion. After biopsy was performed, the specimen was detected infiltration of medulloblastoma cells. Bone scintigram showed a single lesion and MRI of brain and spinal cord revealed no recurrence of the central nervous system lesions. He underwent local irradiation and systemic chemotherapy with ICE regimen. This is the rare case of extracranial metastasis following remission of medulloblastoma in childhood.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Cisplatin represses transcriptional activity from the minimal promoter of the O6-methylguanine methyltransferase gene and increases sensitivity of human gallbladder cancer cells to 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-2-chloroethyl)-3-nitrosourea.

O(6)-methylguanine methyltransferase (MGMT) repairs O(6)-alkylguanine in cellular DNA introduced by the clinically used alkylating drug 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU). Thus, cancer cells with MGMT expression are resistant to ACNU treatment. Cisplatin has been reported to suppress MGMT expression; however, the molecular mechanism by which cisplatin reduces MGMT expression remains to be elucidated. Using gallbladder cancer cells (KMG-C) expressing MGMT, we analyzed whether a low dose of cisplatin suppresses MGMT expression, followed by an enhanced drug effect of ACNU in vitro and in vivo. We also investigated the promoter region critical for the transcriptional repression of MGMT gene by cisplatin using 5 deletion mutants in reporter promoter assays. In RT-PCR analysis, the expression of MGMT mRNA in KMG-C cells was dose- and time-dependently repressed. Drug sensitivity to ACNU was increased 2-fold by pretreatment with cisplatin, compared with only ACNU treatment, in MTT assays as well as tumor-bearing nude mice. Although the 5'-flanking region is deleted as far as -69 bp upstream of the transcription start site, cisplatin dose dependently inhibited luciferase activity. However, cisplatin did not cause such repression when 59 bp region from -69 to -10 bp was deleted. We confirmed that cisplatin enhanced sensitivity to ACNU in KMG-C cells expressing MGMT both in vitro and in vivo. Furthermore, a low dose of cisplatin repressed the transcription of the MGMT promoter. The 59 bp region in the MGMT promoter was crucial for repression by cisplatin. These results might form the basis of a chemotherapeutic strategy involving alkylating agents via prior cisplatin-induced biochemical modulation.

Antineoplastic Agents↗
PubMed2005

[Resent advances in chemotherapy for malignant brain tumors].

Most malignant brain tumors are resistant to the chemotherapeutic agents because of the existence of several mechanisms or substances such as the blood-brain barrier, genes and proteins. Recently many studies have been started to overcome the chemoresistance. Especially recent advances in the field of molecular biology have contributed to examination of the chemosensitivities of tumor cells. Trials for the individualization of the treatment, so-called Taylor-made therapy, is one of these challenges. Loss of chromosome 1 p and 19 q is considered to be closely related to chemosensitivity in anaplastic oligodendrogliomas. This is one of the breakthroughs in the field of chemotherapy for malignant brain tumors. O6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme which reduces the cytocidal effect of nitrosourea. In order to overcome the chemoresistance, drugs except nitrosourea or some drugs which reduce the MGMT activity are used for tumors expressing MGMT. New technology targeting growth factor receptor such as EGFR or VEGFR is also applied to cancer chemotherapy. On the other hand, multi-institutional cooperative studies have been started to obtain evidence in cancer treatment. Phase II study for a small number of patients is not sufficient to demonstrate the efficacy of the treatment and to establish the standard therapy. Multi-institutional randomized controlled study by JCOG Brain Tumor Study Group is the first trial for the treatment of malignant astrocytomas under well-established quality control and quality assurance systems. It can be a model of clinical trials for malignant brain tumors in Japan.

Antineoplastic Agents, Alkylating↗
PubMed1992

[Adjuvant chemotherapy therapy of breast cancer].

Six to 12 cycles of CMF is regarded as the standard regimen for adjuvant chemotherapy for breast cancer, producing 10-20% increase in survival for premenopausal and node-positive patients. Tamoxifen combined with CMF has induced an additional reduction in recurrence rate only in postmenopausal patients. Oral administration of 5-FU or its derivatives combined with tamoxifen for as long as 1-2 years is the regimen most widely used in Japan for considerable improvement in survival. But it needs further evaluation in comparison with CMF, and in ultimate duration of treatment and better combination with other drugs. Adjuvant chemotherapy for node-negative patients is advocated in the U.S., where the recurrence rate is as high as 30%. Only 10% of Japanese n0 patients undergo recurrence. Therefore, adjuvant therapy should be given only to high-risk patients.

Aged↗
PubMed1992

[BH-AC.nitrosourea-therapy for refractory or relapsed malignant lymphoma].

Thirty patients with refractory or relapsed non-Hodgkin's lymphoma were treated with behenoyl ara-C (BH-AC) and nitrosoureas. Sixteen patients (53%) had a diffuse, large cell lymphoma and 22 patients (73%) had a stage IV disease. BH-AC, 250 mg/body, in combination with ACNU or MCNU, 50 mg/body, was administered by drip infusion for two days (Day 1, 2) every 3 to 4 weeks. Six patients (20%), all of them relapsed cases of diffuse lymphoma, obtained complete remission lasting one to six (mean: 2.5) months and 15 patients (50%) obtained partial remission lasting one to five (mean: 2.7) months. The major side effect was thrombocytopenia, and nine patients (30%) had required platelet-transfusions. There was no case complicated by infection due to prolonged neutropenia. Therefore, we conclude that BH-AC.Nitrosourea-therapy is very useful for the salvage chemotherapy of malignant lymphoma.

Adult↗
PubMed2005

Down-regulation of O6-methylguanine-DNA methyltransferase gene expression in gliomas by platinum compounds.

Forty-two patients with malignant gliomas that had received two courses of chemotherapy more than 2 months apart were examined. Among these 42 patients, 31 were treated with 1-(4-amino-2-methyl-5-pyrimidynyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU), and 11 were treated with platinum compounds such as cis-platinum (CDDP) or carboplatin (CBDCA), as the first-line chemotherapy. The response rate of the second chemotherapy in the 31 patients treated first with ACNU was significantly lower than that in the 11 patients treated with platinum compounds, regardless of the type of the second chemotherapy (P=0.0292 by Fisher's exact probability test). O(6)-methylguanine-DNA methyltransferase (MGMT) mRNA expression was measured twice by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) using Sybr-Green I in 16 of 42 patients. The relative quantitation value (RQV) of MGMT mRNA normalized to the level of 2-microglobulin decreased after chemotherapy in all 5 patients treated with platinum compound. U373MG and A172 human glioma cells were cultured for 5 days with 1 microM of CDDP or 4 microM of CBDCA. The RQV of MGMT in these cells treated with platinum compounds obviously decreased, and these cells were more sensitive to ACNU than the control cells based on colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Both the clinical findings and laboratory results suggest that platinum compounds may play a role in the down-regulation of MGMT mRNA expression and up-regulation of the sensitivity to ACNU. Platinum compounds may be strong candidates for use as first-line chemotherapeutic agents against malignant gliomas.

Adult↗
PubMed1992

[Comparison of surgical therapy and combined irradiation in rectal cancer--second report. Effect of irradiation and ACNU on the tumor].

As part of a joint study on preoperative radiotherapy for developing an optimal mode of rectal cancer therapy, ACNU sensitization was studied in a total of 120 cases, with the cooperation of 48 facilities participating nationwide. The following results were obtained. Improvement in depth of invasion was more distinct in the combination preoperative therapy-ACNU group than in the preoperative radiotherapy group, with no other significant differences between the two. This finding suggests that dose and administration method could be improved. White blood cells and platelets were reduced in some cases of the ACNU combination group, but these reductions were not serious enough to impede surgical procedures. In addition, no significant difference in complications was noted between the two.

Adenocarcinoma↗