Combination chemotherapy (RCM protocol: response-oriented cyclic multidrug protocol) for the acute or lymphoma type adult T-cell leukemia.

43 patients with the acute or lymphoma type ATL were treated with the new combination chemotherapy (RCM protocol: response-oriented cyclic multidrug protocol) between January 1989 and December 1991. Complete response (CR) and partial response (PR) were achieved in 20.9% and 65.1% of all treated patients respectively. The median duration of survival was 6.0 months. The survival duration of patients with a high serum lactate dehydrogenase (LDH) value (> or = 1,000 unit) and/or a poor performance status (PS) (PS 3 or 4) were also improved but not in patients with a severe leukocytosis (> or = 35,000/microliters). Toxicity was mild (grade 1 or 2) except hematologic toxicity in 4 patients (9.3%) and alopecia in one patient (2.3%). In spite of many patients with a poor PS (PS 3 or 4), our chemotherapeutic results are equal or superior to other previous reports. It seems that response-oriented chemotherapy is suitable for the ATL patients with poor prognostic factors. These results indicate that the RCM protocol is very useful as the first choice chemotherapy for the acute or lymphoma type ATL.

Elevated soluble CD4 levels in the cerebrospinal fluid in patients with adult T-cell leukemia.

Levels of the soluble form of the leukocyte surface antigen CD4 (sCD4) were measured by enzyme linked immunosorbent assay (ELISA) in the cerebrospinal fluid (CSF) of patients with adult T-cell leukemia (ATL) and other malignant and non-malignant diseases. All patients with ATL and meningeal infiltration had markedly elevated levels of sCD4 in the CSF (53.7 +/- 34.9 U/ml). ATL patients without CSF pleocytosis often had elevated levels of sCD4 (15.1 +/- 9.2 U/ml). Non-ATL patients with CSF pleocytosis had elevated levels of sCD4 (23.3 +/- 12.2 U/ml) and those without CSF pleocytosis also showed elevation of sCD4 levels (16.8 +/- 9.3 U/ml). However, the mean levels of sCD4 in CSF from these patients were significantly lower than ATL patients with meningeal infiltration. Soluble CD4 in the CSF from healthy volunteers were below the detectable limit. We conclude that meningeal infiltration of CD4(+) ATL cells is strongly associated with elevated sCD4 levels in CSF, and some part of sCD4 in CSF may be originated from the native cells in the CNS as a response of inflammatory stimulations. Therefore, measurement of sCD4 may be useful in the diagnosis of meningeal infiltration and/or meningeal irritation in patients with ATL.

[Oral administration of low-dose etoposide for maintenance chemotherapy in adult T cell leukemia patients].

We studied the effectiveness of low-dose, oral administration of etoposide for maintenance chemotherapy of patients with adult T cell leukemia (ATL). Sixteen patients (9 males and 7 females) in remission (9 in complete remission and 7 partial remission) were orally administered 25 or 50 mg/day of etoposide. Median response duration of all the patients to the therapy was 18.6 months, ranging from 5.0 to 34.0 months. Thirteen out of the 16 patients relapsed, and 9 of them died of tumor progression. Appetite loss occurred in one case, without any other severe side effects. It has been suggested, therefore, that oral administration of the etoposide is useful for maintenance chemotherapy in ATL patients.

Involvement of the Golgi region in the intracellular trafficking of cholera toxin.

The intracellular pathway following receptor-mediated endocytosis of cholera toxin was studied using brefeldin A (BFA), which inhibited protein secretion and induced dramatic morphological changes in the Golgi region. In both mouse Y1 adrenal cells and CHO cells, BFA at 1 micrograms/ml caused a 80-90% inhibition of the cholera toxin (CT)-induced elevation of intracellular cAMP. The inhibition of the cytotoxicity of CT by BFA was also observed in a rounding assay of Y1 adrenal cells. The inhibition of CT cytotoxicity by BFA was dose dependent, with the ID50 value similar to the LD50 of BFA in Y1 adrenal cells. Binding and internalization of [125I]-labeled cholera toxin in Y1 adrenal cells was not affected by BFA. Unlike the BFA-sensitive cell lines such as Y1 adrenal and CHO cells, BFA at 1 micrograms/ml did not inhibit the cytotoxicity of CT in PtK1 cells, of which the Golgi structure was BFA-resistant. These results strongly suggest that a BFA-sensitive Golgi is required for the protection of CT cytotoxicity by BFA. In contrast, elevation of the intracellular cAMP by forskolin, which acts directly on the plasma membrane adenylate cyclase, was not affected by BFA. These observations indicate that the intoxication of target cells by CT requires an intact Golgi region for its intracellular trafficking and/or processing. In this respect, CT shares a common intracellular pathway with ricin, Pseudomonas toxin, and modeccin, even though their structures and modes of action are very different.

Isolation and characterization of a brefeldin A-resistant mutant of monkey kidney Vero cells.

Brefeldin A (BFA) is a fungal antibiotic which disrupts protein transport between the endoplasmic reticulum and the Golgi. A BFA-resistant mutant of monkey kidney Vero cells, BER-40, which exhibited about a 90-fold increase in the LD50 of BFA (5.2 ng/ml for Vero cells versus 460 ng/ml for BER-40 cells), has been isolated. The increased resistance of BER-40 cells toward BFA was also manifested in a greatly reduced inhibition of protein secretion by BFA in the mutant and a lack of protection by BFA of the mutant cells from ricin cytotoxicity. Somatic cell hybridization between the Vero and BER-40 cells showed that the BFA-resistance in BER-40 behaved as a codominant trait. The structure of the Golgi region, as examined by immunofluorescence microscopy with antibodies against Golgi markers (the 110-kDa protein and mannosidase II) or with fluorescent lipid NBD-ceramide, was unchanged in the mutant cells as compared to that in the wild-type cells. Treatment of Vero cells with BFA (1 micrograms/ml) or with 2-deoxyglucose plus sodium azide resulted in a rapid release of the 110-kDa protein, mannosidase II, and NBD-ceramide from the Golgi membrane to a more diffuse distribution in the cytosol. In contrast, these three Golgi markers remained to be Golgi-associated following treatment of BER-40 cells with BFA or with 2-deoxyglucose plus sodium azide. Immunoblotting of cell extracts from Vero and BER-40 cells with monoclonal antibody against the 110-kDa protein did not reveal any significant difference in the level of this Golgi marker in the mutant cells. These data suggest that the BFA-resistance mutation in BER-40 has rendered the cyclic pathway of the 110-kDa protein assembly to the Golgi membrane resistant to both BFA and 2-deoxyglucose plus sodium azide.

[Chronic myelogenous leukemia with blastic crisis in which expression of P-glycoprotein was associated with resistance to chemotherapy].

A 55-year-old woman with chronic myelogenous leukemia developed a lymphoid blast crisis (BC) 10 months after diagnosis. By using immunoblotting with a monoclonal antibody against P-glycoprotein (P-gp) C219, her leukemia cells from the first and 3rd crises were shown to be negative for the P-gp, while the cells of the 4th crisis were detected to have a high level of P-gp. This patient did not respond to chemotherapy with several anti-cancer agents in the 4th crisis, although complete remission was achieved in the first, second and third crises after administration of agents including vincristine and prednisolone. Therefore the expression of P-gp in the 4th BC might have been closely related to the resistance to chemotherapy.

Tumor necrosis factor-beta in the serum of adult T-cell leukemia with hypercalcemia.

Serum tumor necrosis factor-beta (TNF-beta) from patients with adult T-cell leukemia (ATL) was studied by a sandwich enzyme-linked immunosorbent assay (ELISA) developed in our laboratory using biotinylated monoclonal anti-TNF-beta and recombinant TNF-beta. Seven of eight patients with hypercalcemia showed elevation of serum TNF-beta. On the other hand, TNF-beta could not be detected by the ELISA in 28 patients without hypercalcemia. The lower detection limit in this assay was 100 pg/mL, corresponding to 500 pg/mL by the conventional method. In two patients serum TNF-beta level decreased after treatment in association with the level of serum calcium. Furthermore, immuno-staining using anti-TNF-beta and avidin-biotin complex showed the presence of cytoplasmic TNF-beta in not only human T-cell leukemia virus type I infected cell lines, but also freshly isolated cells from ATL patients with hypercalcemia. The actual biologic activity of TNF-beta in serum was confirmed by a conventional bioassay in a patient with hypercalcemia, and its cytotoxic activity was inhibited by the addition of anti-TNF-beta antibody in the assay. These results suggested that serum TNF-beta might be one of the factors contributing to the hypercalcemia, at least in patients with ATL.

Interaction of organic chemicals with P-glycoprotein in the adrenal gland, kidney, and a multidrug-resistant KB cell.

P-glycoprotein (P-gp) is thought to mediate the transport of anti-cancer drugs and to be responsible for the multidrug-resistant (MDR) phenotype in tumor cells. However, the function of P-gp in normal tissues is still not well understood. We present evidence indicating that the active efflux of several structurally unrelated organic compounds is mediated by P-gp in multidrug-resistant KB (KB-C2) cells and that these compounds interact with P-gp in the kidney and adrenal gland. The photoactive radioactive calcium channel blocker [3H]azidopine labels a protein of approximately 140 kDa in crude membrane fractions from human kidney and adrenal gland and a 130-kDa protein from bovine adrenal gland. These photolabeled proteins are immunoprecipitated with an anti-P-gp antibody. Photolabeling is inhibited by vinblastine, reserpine, and several other organic chemicals. These data indicate that the kidney and adrenal gland express P-gp (or a protein closely related to P-gp) that can interact with several organic compounds and that the P-gp expressed in these tissues has a drug-binding site similar to that of P-gp in KB-C2 cells. Our findings thus strongly support the hypothesis that P-gp can transport a wide variety of organic chemicals as well as anti-cancer drugs and that one of the physiological functions of P-gp is the excretion of certain classes of organic compounds.

Expression of P-glycoprotein in adult T-cell leukemia cells.

We have examined the expression of P-glycoprotein (P-gp) in adult T-cell leukemia (ATL) samples from 25 patients. Based on immunoblotting with a monoclonal antibody against P-gp, C219, 8 of 20 ATL patients were P-gp positive at the initial presentation. All 6 patients at the relapsed stage were P-gp positive, and refractory to chemotherapy. The expression of MDR1 mRNA in P-gp-positive ATL cells was increased at the relapsed stage of one patient. P-gp of this patient was photolabeled with [3H]azidopine and the labeling was inhibited with nimodipine, vinblastine and progesterone. These results suggest that P-gp expressed in ATL cells from patients at relapsed stage has the same binding site(s) for the drugs as that in multidrug resistant cells, and is correlated with the refractory nature of the cells to chemotherapy.

Expression of the multidrug transporter, P-glycoprotein, in acute leukemia cells and correlation to clinical drug resistance.

The overexpression of a cell-surface glycoprotein termed P-glycoprotein (P-gp) is frequently associated with multi-drug resistance (MDR) in cell lines in vitro. To evaluate the implications of P-gp expression in clinical drug resistance, the authors examined the expression of P-gp in leukemia cells from patients with acute myelogenous leukemia (AML) and those with acute lymphoblastic leukemia (ALL) at initial presentation and relapse, using immunoblotting with a monoclonal antibody against P-gp, C219. Nine of 17 patients with AML and four of 11 patients with ALL had P-gp-positive results at the initial presentation, and most P-gp-positive patients did not respond to chemotherapy. Four of seven patients at the relapsed stage and all three patients with preceding myelodysplastic syndrome had P-gp-positive results. The expression of P-gp and clinical refractoriness to chemotherapy were highly correlated. These data indicate that the expression of P-gp is closely related to clinical drug resistance in acute leukemia.

Purification and tissue distribution of human thymidine phosphorylase; high expression in lymphocytes, reticulocytes and tumors.

Thymidine phosphorylase (dThdPase) is an enzyme involved in pyrimidine nucleoside metabolism, but little is known about its physiological functions. We purified dThdPase from human placenta and used it for antibody preparation. The purified material appears as a single band at 55,000 dalton on sodium dodecylsulfate-polyacrylamide gel electrophoresis. We obtained a specific antibody raised in rabbits that detected a single polypeptide with a molecular weight of 55,000 dalton in the post nuclear homogenates of several human tissues, on immunoblotting. Using the same technique, dThdPase was highly expressed in the liver, lung, spleen, lymph nodes and peripheral lymphocytes. Immunohistochemical staining revealed that macrophage-like cells contained a much higher amount of dThdPase than parenchymal cells in the liver and lung. dThdPase was found to be highly expressed in T- and B-cell-type malignant lymphoma cells, but low in lymphoblastic and myeloblastic leukemia cells. We also found that carcinomas in the stomach, colon and ovary contained higher amounts of this enzyme than non-neoplastic regions of the tissues. These data suggest that dThdPase plays a role in proliferation and/or differentiation of leukocytes and in cancer proliferation.

Expression of the multidrug transporter, P-glycoprotein, in chronic myelogenous leukaemia cells in blast crisis.

The overexpression of a cell-surface glycoprotein termed P-glycoprotein (P-gp) is frequently associated with multidrug resistance (MDR) in cell lines in vitro. To evaluate the implications of P-gp expression in clinical drug-resistance, we examined the expression of P-gp in fresh leukaemia cells from chronic myelogenous leukaemia (CML) patients in blast crisis. By using immunoblotting with a monoclonal antibody against P-gp, C219, we showed that leukaemia cells from three CML patients in blast crisis were P-gp negative at the stage when these patients were in complete remission, and that the cells showed high levels of P-gp expression at times when the same patients had relapsed and had not responded to chemotherapy. Six out of 11 patients (nine in the refractory state) were P-gp positive and they rarely responded to chemotherapy. These data suggest that the expression of P-gp is closely associated with drug-resistance in CML.

Cytoplasmic orientation and two-domain structure of the multidrug transporter, P-glycoprotein, demonstrated with sequence-specific antibodies.

The predicted cytoplasmic orientation and two-domain structure of the multidrug efflux pump P-glycoprotein were demonstrated with sequence-specific antibodies. We synthesized peptides corresponding to amino acid residues, Glu393-Lys408 (anti-P) and Leu1206-Thr1226 (anti-C) in P-glycoprotein from human mdr1 cDNA and used these peptides to produce polyclonal antibodies. From the primary structure of P-glycoprotein, and anti-C antibody is expected to recognize another position, Leu561-Thr581, in the duplicate structure of P-glycoprotein, but anti-P recognizes only one site. These antibodies bind to multidrug-resistant cells (KB-C2) with permeabilized plasma membrane but do not bind to nonpermeabilized KB-C2 cells or parental KB cells, supporting the predicted cytoplasmic orientation of these sequences. With immunoblotting of the membrane fractions from KB-C2 cells, a major 140-kDa polypeptide of the P-glycoprotein was detected with both anti-P and anti-C. Two minor polypeptides with molecular mass of 95 and 55 kDa were also detected. When membrane vesicles were digested mildly with trypsin, the amount of these two polypeptides increased. Anti-P detected only the 95-kDa polypeptide, and anti-C detected both 95- and 55-kDa polypeptides. Achromobacter lyticus protease I (lysyl endopeptidase) and Staphylococcus aureus V8 protease also produced two polypeptides with similar molecular weights. Absorption into lectin-agarose beads and labeling with [3H]glucosamine indicated that the 95-kDa polypeptide was glycosylated but that the 55-kDa polypeptide was not. These two polypeptides as well as P-glycoprotein were photoaffinity-labeled with a calcium channel blocker, [3H]azidopine, but most of the label was found in the 55-kDa polypeptide. The yield of labeled fragments from membrane vesicles photolabeled after digestion with trypsin was similar to that from membrane vesicles digested with trypsin after photolabeling. These data indicate 1) that the 95-kDa polypeptide is the fragment corresponding to the amino-terminal half of P-glycoprotein containing sugar chains; 2) that the 55-kDa polypeptide is the carboxyl-terminal half which was mainly labeled with [3H]azidopine; and 3) that P-glycoprotein has a relatively rigid structure with a small number of protease-sensitive sites and its global structure is not destroyed by tryptic cleavage.

Biosynthesis, processing and half-life of P-glycoprotein in a human multidrug-resistant KB cell.

The biosynthesis, processing, and half-life of the drug efflux pump, P-glycoprotein, were studied in human multidrug-resistant KB (KB-C2) cells selected for resistance to colchicine. An antibody directed against a synthetic oligopeptide corresponding to the amino-acid sequence (Glu-393-Lys-408) of P-glycoprotein from human mdr1 cDNA was prepared in rabbits. With immunoblotting and immunoprecipitation, we detected a 140-170 kDa protein in KB-C2 cells but not in parental sensitive KB cells. KB-C2 cells made a 125 kDa precursor that was slowly processed (t1/2 = 45 min) to the mature form of 140-150 kDa. The processing rate of P-glycoprotein was slower than that of low-density lipoprotein receptor. We detected another 160-180 kDa smear band, which might be a completely denatured form of P-glycoprotein. With immunoblotting, a minor band of high molecular mass (greater than 500 kDa) was also detected and this form increased after the cells were treated with chemical cross-linker, 1,5-difluoro-2,4-dinitrobenzene. The half-life of P-glycoprotein was long; no significant loss of P-glycoprotein was observed within 24 h after synthesis. Cells treated with tunicamycin produced a 120 kDa form of P-glycoprotein which was no longer processed but showed stability similar to that of the mature 140-150 kDa form. Agents that reverse multidrug resistance, phorbol ester and transport substrate did not affect the stability of P-glycoprotein.

[Expressions of 2H4 and 4B4 antigens on ATL cells].

We studied the expression of 2H4 and 4B4 on the surfaces of leukemia cells from 17 patients with adult T-cell leukemia (ATL) as well as of cells belonging to 2 T-cell lines derived from ATL patients. The effects of the supernatants obtained from culture fluids of the ATL cells and the T-cell lines on IgG production of a human B-cell line, CESS cells, were also examined. On the surfaces of the ATL cells from 15 out of 17 cases and of the cells of 2 T-cell lines 4B4 obviously existed at higher percentage than 2H4 and more than 80% of ATL cells from 16 out of these 17 cases showed the expression of T4 (CD4). These findings revealed that the most of ATL cells had a helper-inducer phenotype. Supernatants (Sups) of culture fluids of ATL cells from 4 patients and those of 2 T-cell lines were added at various concentrations to the CESS cells. In only 1 Sup from ATL patient enhanced the IgG production of the CESS cells at lower concentration. However, other 5 Sups suppressed the IgG production of the CESS cells in proportion to the increase of Sup added. These results showed that phenotypical type of ATL cells does not always correspond to their functions, and the ATL cells may produce humoral factors that regulate B cell functions.