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Biomedical subjects

K Nooter

Publications and source records attributed to K Nooter.

At least 91 records · Page 5Linked to original sources
PubMed1991

A phase II study of epidoxorubicin in colorectal cancer and the use of cyclosporin-A in an attempt to reverse multidrug resistance.

We determined the ability of the multidrug resistance (MDR) reversal agent cyclosporin-A to increase anthracycline drug accumulation in colorectal tumour cells in vitro, using the technique of on-line flow cytometry. Data of four previously untreated patients showed that cyclosporin-A can increase intracellular net-uptake of daunorubicin. A phase II study was initiated in 24 colorectal cancer patients. They received cyclosporin-A at a dose of 3 mg kg-1 over 1 h as i.v. infusion, at 7 h and at 1 h preceding cytotoxic drug administration. At the end of the second cyclosporin-A administration epidoxorubicin 90 mg m-2 was administered as i.v. bolus. Cycles were repeated every 3 weeks. Median cyclosporin-A peak blood levels and levels at 18 h after cytotoxic drug administration appeared to be 6248 ng ml-1 and 1012 ng ml-1 respectively. Only one partial response was observed, despite these high cyclosporin-A levels. Cyclosporin-A did not cause major toxicity, only a 29% incidence of hot flushes was observed. Epidoxorubicin toxicities were as expected but the frequency of severe leucocytopenia was striking. This treatment schedule can not be considered active in colorectal cancer.

Adult↗
PubMed1990

Expression of mdr1 and mdr3 multidrug-resistance genes in human acute and chronic leukemias and association with stimulation of drug accumulation by cyclosporine.

We determined the expression levels of the mdr1 and mdr3 multidrug-resistance genes (also known as PGY1 and PGY3, respectively) in peripheral blood cells from 69 adult patients with acute and chronic leukemias, using an RNase protection assay. Expression of mdr1 was found in samples from patients with acute nonlymphocytic leukemia (13 of 17), chronic myelocytic leukemia (CML, chronic phase, 10 of 10; blast crisis, three of four), acute lymphocytic leukemia (ALL, eight of 11), B-cell chronic lymphocytic leukemia (B-CLL, 17 of 17), hairy cell leukemia (HCL, one of two), and T-cell prolymphocytic leukemia (one of one), but not in B-cell prolymphocytic leukemia (B-PLL, 0 of seven). Expression of mdr3 was only detected in samples from B-cell lymphocytic leukemias: CML, lymphoid blast crisis (one of one), B-cell ALL (two of two), B-CLL (17 of 17), B-PLL (seven of seven), and HCL (two of two). In vitro drug uptake studies by on-line flow cytometry showed that in leukemia cells expressing either mdr1 or mdr3, the steady-state accumulation of daunorubicin could be significantly increased by addition of cyclosporine and, to a lesser extent, by verapamil. Because cyclosporine and verapamil are known as inhibitors of the mdr1-encoded P-glycoprotein drug-efflux pump, and because the mdr1 and mdr3 genes are highly homologous, our data suggest that the mdr3 gene encodes a functional drug pump in B-cell lymphocytic leukemias. The results of this study may have implications for clinical therapy for acute or chronic leukemias expressing the mdr1 or mdr3 gene, in particular, treatment with combinations of cytotoxic drugs plus agents that reverse multidrug resistance. Since mdr1 and mdr3 are frequently expressed in untreated as well as treated leukemia, such combination therapy should be considered for untreated patients as well as treated patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Expression of the mdr3 gene in prolymphocytic leukemia: association with cyclosporin-A-induced increase in drug accumulation.

Typical multidrug resistance in human and animal cell lines is caused by overactivity of an unidirectional transmembrane drug efflux pump, encoded by the MDR genes, called mdr genes in mice and humans and pgp genes in hamsters. In humans, two mdr genes, mdr1 and mdr3, with approximately 80% nucleotide homology, have been identified. There is increasing evidence that overexpression of the mdr1 gene plays a role in resistance to anticancer agents in specific tumor types. However, currently no data are available on a possible role for mdr3 in drug resistance. Here we report high levels of expression of mdr3 gene sequences in leukemic cells from 6 out of 6 patients with prolymphocytic leukemia (PLL). No mdr1 expression was detected in 5 out of 6 of these samples, whereas a low level of mdr1 expression was found in a sample from one PLL patient in the course of transformation to non-Hodgkin's lymphoma. Except for this patient, all other PLL cases studied had not received prior chemotherapy. In vitro drug uptake studies showed that daunorubicin accumulation in PLL cells was increased by cyclosporin A. Since cyclosporin A is an inhibitor of the mdr1-encoded P-glycoprotein drug pump, these data suggest that in PLL cells mdr3 also codes for a drug efflux pump. Our findings could partly explain the primary refractoriness of PLL to chemotherapy.

Adult↗
PubMed1990

Overexpression of the mdr1 gene in blast cells from patients with acute myelocytic leukemia is associated with decreased anthracycline accumulation that can be restored by cyclosporin-A.

Typical multi-drug resistance (MDR) in human and animal cell lines is caused by overactivity of a unidirectional drug efflux pump. This pump is composed of a 170-kDa transmembrane glycoprotein (P-glycoprotein) that is encoded by the so-called mdr1 gene. The functionally relevant characteristic of MDR cells is a defect in drug accumulation that can be restored by agents which inhibit the P-glycoprotein pump. The purpose of our study was to find out whether P-glycoprotein inhibitors could increase the daunorubicin (DNR) accumulation in acute myelocytic leukemia (AML) cells, overexpressing the mdr1 gene. Using dot blot analysis with an mdr1-specific cDNA probe, we identified leukemic cell samples, obtained from chemotherapy-resistant AML patients, that had relatively high levels of mdr1 expression. These leukemic cells showed a reduced ability to accumulate DNR in vitro, as quantitated by flow cytometry. Addition of cyclosporin-A (Cy-A), a drug known to inhibit the P-glycoprotein pump, to the incubation medium resulted in an increase (up to 60%) in steady-state drug uptake by the leukemic cells. The degree of Cy-A-induced increase in drug accumulation in the leukemic cells correlated approximately with the level of overexpression of the mdr1 gene. Our data indicate that Cy-A is a good candidate for combination chemotherapy with cytotoxic drugs in clinical trials, aimed at the treatment of drug resistance in AML.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Susceptibility of acute myeloid leukemia (AML) cells from clinically resistant and sensitive patients to daunomycin (DNR): assessment in vitro after stimulation with colony stimulating factors (CSFs).

Chemosensitivity of purified AML blasts to daunomycin was examined under conditions of CSF stimulation and compared with clinical outcome of DNR combination chemotherapy. AML blasts from 16 patients were purified, incubated serum-free in the presence of optimal concentrations of a complete cocktail of IL-3, GM-CSF and G-CSF to provoke cell proliferation maximally, and DNR drug sensitivity in vitro was assessed by inhibition of DNA synthesis in response to titrated DNR concentrations. The sensitivity of proliferating AML cells to DNR did not correlate with the clinical response of the patients as identical dose-response curves were obtained for complete responders (n = 6), partial responders (n = 5) and resistant cases (n = 5). As a major part of the AML population was induced to enter DNA synthesis in vitro, these data suggest that the manoeuvre of cell cycle stimulation has abrogated cellular resistance to daunomycin and rendered in vivo, apparently refractory cells susceptible to the anthracycline.

Colony-Stimulating Factors↗
PubMed1990

Effect of cyclophosphamide pretreatment on daunorubicin in rat acute leukaemia model.

The total number of leukaemic cells at the time of therapy may affect the tissue and target cell distribution and antitumour efficacy of cytotoxic drugs. The effects of low dose cyclophosphamide pretreatment on daunorubicin concentrations in leukaemic bone marrow were investigated in rats. At day 12 after transplantation of the leukaemia, rats were injected intraperitoneally with cyclophosphamide (30 mg/kg). 2 days later the leukaemic rats received daunorubicin intravenously (7.5 mg/kg). Cyclophosphamide pretreatment led to a significant increase in daunorubicin concentration in the femoral bone marrow, by a factor of about 7. The log leukaemic stem cell kill (LCK) values, as estimated by a survival assay, were 1.8, 0.7, and 5.4 for the leukaemic rats injected with cyclophosphamide (day 12), with daunorubicin (day 14), or with cyclophosphamide (day 12) plus daunorubicin (day 14), respectively). The simultaneous administration of cyclophosphamide and daunorubicin at day 14, induced a LCK of 2.7, a value that was the sum of the LCKs of cyclophosphamide and daunorubicin alone. Low-dose cyclophosphamide pretreatment led to an increased daunorubicin accumulation in femoral bone marrow of leukaemic rats, and was synergistic with daunorubicin.

Animals↗
PubMed1990

Combination therapy of ACNU and ifosfamide in tumor bearing mice with M2661 breast cancer, B16 malignant melanoma or C38 colon cancer.

Three murine tumor lines, B16 melanoma, C38 colon cancer and M2661 breast cancer, were used to evaluate the therapeutic efficacy of the drug combination ACNU and ifosfamide. For each tumor type five treatment groups of 12 mice each were studied, which respectively received 16.5 mg/kg ACNU, 150 mg/kg ifosfamide, 33 mg/kg ACNU, 300 mg/kg ifosfamide or 16.5 mg/kg ACNU + 150 mg/kg ifosfamide. One group served as controls. Growth delay was measured as the endpoint. In the B16 and C38 tumor lines both drugs were active and showed additive antitumor effects. However, no synergism was observed. Neither ACNU or ifosfamide or the combination of both had any activity against the M2661 tumor line.

Animals↗
PubMed1990

Reversal of drug-resistance by cyclosporin-A in a patient with acute myelocytic leukaemia.

The emergence of resistant leukaemia in a patient with acute myeloid leukaemia (AML) was evaluated during clinical progression of the disease. At relapse, a decrease of the intracellular accumulation of daunorubicin (DNR) as determined by real time flow cytometry was associated with a relative overexpression of RNA encoding for the multidrug resistance phenotype (MDR1), and by a decreased in vitro sensitivity to DNR of clonogenic AML cells (IC50 0.8-3.4 microM). Intracellular DNR accumulation and in vitro DNR sensitivity could be completely restored by adding cyclosporin-A (3 microM) to the cells. At progressive relapse the patient was treated with re-induction therapy (DNR 30 mg/m2 x 3, cytarabine 200 mg/m2 x 7) to which cyclosporin-A was added (Cy-A 4 mg/kg twice daily for 3 d. 2.5 mg/kg twice daily for 2 d), which resulted in elimination of the MDR1 positive AML cells with restoration of the original DNR accumulation and in vitro sensitivity. After 12 weeks the resistant clone reappeared in the blood and bone marrow.

Aged↗
PubMed1989

Effects of cyclosporin A and verapamil on the intracellular daunorubicin accumulation in Chinese hamster ovary cells with increasing levels of drug-resistance.

Multidrug-resistance (MDR) is characterized by the presence of a 170 kDa glycoprotein (P-glycoprotein) in the plasma membrane. P-glycoprotein is thought to act as an efflux pump, leading to reduced drug accumulation in MDR cells. This defect in drug accumulation can be overcome by membrane transport modulating agents (MTMAs). We determined the concentration of MTMA needed for maximal restoration of daunorubicin content in 4 Chinese hamster ovary cell lines with increasing levels of drug-resistance using flow cytometry. Stimulation of daunorubicin accumulation occurred in a dose-dependent manner. The required level of MTMA needed for maximal drug accumulation increased with the level of drug-resistance. CHrA3 cells, which have a level of resistance comparable to clinical samples, needed relatively low concentrations of MTMA for maximal restoration of drug accumulation. This indicates that, in trial combining drugs and MTMAs, low dosages of MTMAs could be sufficient for optimal potentiation of cytotoxicity.

Animals↗
PubMed1989

A rapid and sensitive flow cytometric method for the detection of multidrug-resistant cells.

Multidrug-resistant (MDR) cells are characterized by a defect in drug accumulation caused by activity of an energy-dependent rapid drug efflux pump. The action of this drug pump can be inhibited by specific agents, referred to as membrane transport modulating agents (MTMAs), resulting in a restoration of the intracellular drug accumulation. This paper presents a flow cytometric assay for the detection of MDR cells, which is based on the ability of these cells to respond to MTMAs. Daunorubicin net-uptake kinetics were measured of anthracycline-sensitive (A2780/S) and -resistant (A2780/R) human ovarian carcinoma cells in vitro. A2780/R cells accumulated significantly less (about a factor of 5) daunorubicin as compared to A2780/S cells. Addition of verapamil or cyclosporin A to A2780/R cells at steady-state daunorubicin uptake led to a dose-dependent increase in cellular daunorubicin accumulation. The sensitivity of the assay was determined by testing mixtures of A2780/S and A2780/R cells. Analysis of A2780/S cells contaminated with A2780/R cells showed that as few as 2.5% MDR cells could readily be detected in the mixture. In conclusion, this functional assay enables the detection of MDR cells in a heterogeneous cell suspension and is ideally suited for the study of the occurrence of typical MDR in human cancer.

Antibiotics, Antineoplastic↗
PubMed1989

Effect of cyclosporin A on daunorubicin accumulation in multidrug-resistant P388 leukemia cells measured by real-time flow cytometry.

We investigated the mode of action of cyclosporin A (Cy-A) as a modifier of multidrug resistance in P388 mouse leukemia cells. A fluorescence-activated flow cytometer (FCM) was modified with a flow-through cuvette to allow continuous on-line monitoring of daunorubicin uptake in vitro. The addition of Cy-A to multidrug-resistant P388/R cells at steady-state daunorubicin uptake, led to a dose-dependent increase in cellular daunorubicin accumulation, as measured by FCM and high-performance liquid chromatography (HPLC). A linear relationship was found between the daunorubicin concentration in the incubation medium and the Cy-A concentration required for optimal stimulation of cellular anthracycline accumulation. The results of a cytotoxicity assay indicated that Cy-A completely restored the chemosensitivity of the P388/R cells. Intracellular Cy-A measurements in P388/S and P388/R cells showed that P388/R cells accumulated significantly less Cy-A than P388/S cells. Relatively high daunorubicin concentrations could not restore that accumulation defect. These results suggest that Cy-A promotes cellular anthracycline accumulation by competing for an outward drug-transport system that operates in multidrug-resistant cells.

Animals↗
PubMed1987

Pharmacokinetics of daunorubicin as a determinant of response in acute myeloid leukemia.

Twenty-one adult patients with acute myeloid leukemia (AML) were treated with the EORTC LAM-6 remission induction protocol [daunorubicin (DNR) (45 mg/m2, days 1-3), cytarabine (200 mg/m2, days 1-7) and vincristine (1 mg/m2, day 2)]. Pharmacokinetics of DNR were studied at day 1. The concentration of DNR and daunorubicinol were determined in plasma, in white blood cells and in bone marrow. A large variability was observed with respect to (1) the plasma area under the curve (AUC) 0-24 h (range: 0.06-0.37 nmol X h/ml); (2) the white cell AUC 0-24 h (range: 0-441 nmol X h/10(9) cells); and (3) the 1 h bone marrow concentration (range: 0-27 nmol/10(9) cells). In eight patients treated twice, a small intraindividual variability of these parameters was observed. Concentrations in plasma did not correlate with cellular concentrations. All pharmacokinetic parameters in plasma and white cells did not correlate with response to therapy. In patients reaching complete remission (CR), however, the tumor load, as expressed by the number of blast cells present in the untreated bone marrow, was significantly lower than the number of blast cells in patients not reaching CR.

Adult↗
PubMed1987

Effects of verapamil on the pharmacokinetics of daunomycin in the rat.

We compared the pharmacokinetics of daunomycin in two groups of rats: one group was treated with daunomycin (7.5 mg/kg) alone and the other group was treated with daunomycin (7.5 mg/kg) plus the calcium antagonist verapamil (2 X 50 mg/kg i.p.). Due to a much slower decrease in plasma concentrations the daunomycin AUC0----infinity was dramatically increased (8 times) in the animals treated with anthracycline plus verapamil. The daunomycin plasma clearance was found to be decreased about 9 times in the verapamil-treated group. Verapamil had a differential effect on the tissue distribution of daunomycin. Of the organs examined the heart, liver, and lungs showed an increased (about 2-3 times) AUC of daunomycin. In the kidneys and spleen the AUCs of daunomycin were about equal in both groups of rats, while in the femoral bone marrow the daunomycin AUC was significantly reduced by the simultaneous administration of verapamil. Our data suggest that an increased risk for anthracycline-induced cardiotoxicity can be anticipated by the combined treatment of anthracycline drugs with calcium antagonists.

Animals↗