Protein kinase C-theta phosphorylation of moesin in the actin-binding sequence

Moesin, a member of the ezrin-radixin-moesin (ERM) family of membrane/cytoskeletal linkage proteins, is known to be threonine-phosphorylated at Thr558 in activated platelets within its conserved putative actin-binding domain. The pathway leading to this phosphorylation step and its control have not been previously elucidated. We have detected and characterized reactions leading to moesin phosphorylation in human leukocyte extracts. In vitro phosphorylation of endogenous moesin, which was identified by peptide microsequencing, was dependent on phosphatidylglycerol (PG) or to a lesser extent, phosphatidylinositol (PI), but not phosphatidylserine (PS) and diacylglycerol (DAG). Analysis of charge shifts, phosphoamino acid analysis, and stoichiometry was consistent with a single phosphorylation site. By using mass spectroscopy and direct microsequencing of CNBr fragments of phospho-moesin, the phosphorylation site was identified as KYKT*LRQIR (where * indicates the phosphorylation site) (Thr558), which is conserved in the ERM family. Recombinant moesin demonstrated similar in vitro phospholipid-dependent phosphorylation compared with the endogenous protein. The phosphorylation site sequence of moesin displays a high degree of conservation with the pseudosubstrate sequences of the protein kinase C (PKC) family. We identified the kinase activity as PKC-theta on the basis of immunodepletion of the moesin kinase activity and copurification of PKC-theta with the enzymic activity. We further demonstrate that PKC-theta displays a preference for PG vesicles over PI or PS/DAG, with minimal activation by DAG, as well as specificity for moesin compared with myelin basic protein, histone H1, or other cellular proteins. Expression of a human His6-tagged PKC-theta in Jurkat cells and purification by Ni2+ chelate chromatography yield an active enzyme that phosphorylates moesin. PG vesicle binding experiments with expressed PKC-theta and moesin demonstrate that both bind to vesicles independently of one another. Thus, PKC-theta is identified as a major kinase within cells with specificity for moesin and with activation under non-classical PKC conditions. It appears likely that this activity corresponds to a specific intracellular pathway controlling the function of moesin as well as other ERM proteins.

Two unique 5' untranslated regions in mRNAs encoding human 14-3-3 zeta: differential expression in hemopoietic cells

In this report, we describe the identification and characterization of a novel 14-3-3 cDNA using the polymerase chain reaction and the screening of a human bone marrow cDNA library. This cDNA encodes the zeta isoform of 14-3-3 and contains a novel 5' untranslated region (UTR) that is G + C rich and only 50% identical to the 5' UTR in the human placental 14-3-3 zeta cDNA, suggesting that 14-3-3 zeta is encoded by at least two mRNAs. Using specific probes to the 5' UTRs of bone marrow and placental 14-3-3 zeta cDNAs, we studied the expression of each transcript in human hemopoietic cells at various stages of differentiation in the myeloid and lymphoid lineages. Differences in the expression of the bone marrow and placental 14-3-3 zeta transcripts were found, the most notable being the markedly decreased expression of both 14-3-3 zeta transcripts in HL-60 myeloid leukemic cells. Western blot analysis of 14-3-3 zeta levels in HL-60 cells revealed correspondingly decreased levels of 14-3-3 zeta protein compared to Jurkat cells. The differences among cell types of relative expression of the two 14-3-3 transcripts may reflect normal regulatory patterns, while the strikingly decreased expression of both types in HL-60 are more likely to be reflective of its multiple genetic abnormalities which contribute to its transformed phenotype.

A phase II trial of interferon-alpha and 5-fluorouracil in patients with advanced renal cell carcinoma. A Southwest Oncology Group study

BACKGROUND

Renal cell carcinoma is a common neoplasm that is often refractory to treatment. It is occasionally responsive to immunomodulating agents including interferon-alpha, which enhances the effects of 5-fluorouracil upon cells. Combinations of these two drugs have been most frequently tested in patients with gastrointestinal cancers, with some promising results. Because interferon-alpha has activity for renal cell carcinoma, a trial of this combination in patients with this malignancy was undertaken.

METHODS

The Southwest Oncology Group performed a Phase II clinical trial of the combination of 5-fluorouracil and interferon-alpha for recurrent or metastatic renal cell carcinoma. Eligibility criteria included no prior treatment with medications for cancer, a performance status of 2 or better, and bidimensionally measurable disease. The regimen studied consisted of 5-fluorouracil, 750 mg/M2/day, by continuous intravenous infusion on Days 1-5, and interferon-alpha-2b (Intron A), 5 x 10(6)U/M2/day, subcutaneously on Days 1, 3, and 5, repeated every 21 days.

RESULTS

Forty eligible patients were treated; twenty of the 40 underwent a nephrectomy. The regimen was tolerable: 3 patients had Grade 4, and 17 had Grade 3 toxicity. There were 5 partial responses (13% with 95% confidence limits of 4-27%). Median progression free survival for all 40 patients was 4 months and median overall survival was 15 months from the time of registration.

CONCLUSIONS

The combination of 5-fluorouracil and interferon-alpha given by this schedule, although tolerable and occasionally yielding responses, is not an improvement over existing therapies.

A randomized placebo-controlled trial of recombinant human interleukin-11 in cancer patients with severe thrombocytopenia due to chemotherapy

Thrombocytopenia is a complication of cancer treatment that can limit dose intensity. Interleukin-11 (IL-11) is a growth factor that increases platelet production. We conducted a multicenter, randomized, placebo-controlled trial of recombinant human IL-11 (rhIL-11) in 93 patients with cancer who had already been transfused platelets for severe thrombocytopenia resulting from chemotherapy. The patients had received platelet transfusions for nadir platelet counts of < or = 20,000/microL during the chemotherapy cycle immediately preceding study entry. Chemotherapy was continued during the study without dose reduction. Patients were randomized to receive placebo or rhIL-11 at 50 or 25 micrograms/kg subcutaneously once daily for 14 to 21 days beginning 1 day after chemotherapy. Eight of 27 (30%) evaluable patients treated with rhIL-11 at a dose of 50 micrograms/kg did not require platelet transfusions versus 1 of 27 (4%) patients who received placebo (P < .05). Five of 23 (18%) patients treated with rhIL-11 at 25 micrograms/kg avoided platelet transfusions (P = .23). Side effects were fatigue and cardiovascular symptoms, including a low incidence of atrial arrhythmias and syncope. There were no differences among treatment groups in the incidence of neutropenic fever, days of hospitalization, or number of red blood cell transfusions. This study shows that rhIL-11 treatment of a dose of 50 micrograms/kg significantly increases the likelihood that patients who have already been transfused platelets for severe chemotherapy-induced thrombocytopenia will not require platelet transfusions during a subsequent chemotherapy cycle.

Association of 14-3-3 proteins with centrosomes

The 14-3-3 proteins are involved in diverse signal transduction pathways and interact physically with a wide variety of proteins. Here, we report the partial sequence analysis of a human spleen 14-3-3 protein, which was identified as a variant form of the epsilon isoform. A peptide antibody generated to the variant 14-3-3 localizes in the centrosome and spindle apparatus of mouse leukemic FDCP cells by immunofluorescence microscopy. Immunoblots of centrosomes isolated by sucrose density gradient centrifugation of cell lysates disclose only the epsilon and gamma isoforms, while total cellular lysates contain the epsilon, gamma, beta and zeta isoforms of 14-3-3. These data suggest that a subset of total cellular 14-3-3 proteins are localized in the centrosomes and spindle apparatus. A differential localization of the centrosomal 14-3-3 was observed in mouse 3T3 cells. Serum-starved (quiescent) cells lack the centrosomal 14-3-3, but upon serum-stimulation of these quiescent cells, the centrosomal 14-3-3 reappears. We propose that a subset of intracellular 14-3-3 proteins are localized in the centrosome and spindle apparatus, and may in fact, link mitogenic signaling, the cell cycle, and perhaps the centrosome duplication cycle as well.

Phase I evaluation of therapy with four schedules of 5-fluorouracil by continuous infusion combined with recombinant interferon alpha

The purpose of this study was to determine the maximum tolerated dose and dose-limiting toxicities of 5-fluorouracil (5-FU) when administered concurrently with recombinant IFN-alpha using four continuous infusion (CI) dosing schedules of 5-FU. Forty-five patients with advanced or refractory cancers were treated with 5-FU by CI, plus IFN during the infusion only, by one of four schedules: schedule A: 24-h 5-FU infusion repeated weekly, 9 x 10(6) units IFN x 2 doses weekly; schedule B: 48-h 5-FU infusion repeated weekly, 9 x 10(6) units IFN x 4 doses weekly; schedule C: 5-day 5-FU infusion repeated every 3 weeks, 9 x 10(6) units IFN three times weekly; and schedule D: 21-day 5-FU infusion, repeated after 7 days off therapy, 9 x 10(6) units IFN three times weekly. At least three patients were treated at all dose levels. Doses of 5-FU were escalated to the next level if less than one half of the patients at a given level developed grades 2-4 toxicity. The maximum tolerated dose for 5-FU was 2150 mg/m2/week for schedule A (24-h CI), 2350 mg/m2/week for schedule B (48-h CI), 750 mg/m2/day for schedule C (5-day CI), and 175 mg/m2/day for schedule D (21-day CI). Median delivered dose intensities at these levels were 1788 mg/m2/week for schedule A, 2192 mg/m2/week for schedule B, 1250 mg/m2/week for schedule C, and 593 mg/m2/week for schedule D. The dose-limiting toxicities were hematological and gastrointestinal (stomatitis, diarrhea, nausea, anorexia) for schedules A and B and gastrointestinal (mostly stomatitis) for schedules C and D. Severe fatigue due to IFN was rare. Responses correlated with toxicity >/= grade 2, but not with increased dose intensity. Responses were noted in several tumor types on schedules A, B, and D. 5-FU can be combined with IFN using 24- and 48-h high-dose and long-term low-dose CI schedules, with large differences in dose intensity at maximum tolerated dose. Shorter infusions produce less mucosal and more hematological toxicity. Tumor responses were seen on both short- and long-term CI schedules. Future studies can establish the efficacies of these new schedules of 5-FU/IFN administration in specific tumor types.

Identification of enzymatically active Ca2+/calmodulin-dependent protein kinase in centrosomes of hemopoietic cells

In this study, we report the identification of enzymatically active, multifunctional calcium/calmodulin-dependent protein kinase in centrosomes of FDCP1 cells using subcellular fractionation and immunofluorescence techniques. Centrosomes were isolated from detergent lysates of FDCP cells by sucrose density gradient centrifugation and contain tubulin (M(r) = 58 kDa) and centrin (M(r) = 20 kDa) by immunoblotting. Analysis of these fractions with anti-calcium/calmodulin kinase II antibody revealed the presence of the 52 kDa and 56 kDa doublet corresponding to the alpha and the beta/beta' subunits of the enzyme complex. In vitro kinase reactions with isolated centrosomes and in the presence of calcium and calmodulin results in the phosphorylation of several centrosomal proteins.

A prospective evaluation of the roles of allogeneic marrow transplantation and low-dose monthly maintenance chemotherapy in the treatment of adult acute myelogenous leukemia (AML): a Southwest Oncology Group study

Between February 1982 and December 1986, the Southwest Oncology Group conducted a prospective study in patients with newly diagnosed acute myeloid leukemia (AML) with two objectives: to evaluate the role of allogeneic marrow transplantation for patients in first remission, and to evaluate the role of low-dose monthly maintenance therapy in those patients not transplanted in first remission. Among 522 evaluable patients, 295 (57%) achieved complete remission (CR), including 70% of patients age 49 or less. Twenty-four patients (15%) age 49 or less in CR were not HLA-typed, mostly because of financial constraints. HLA-identical donors were found for 39% of patients, of whom two-thirds were transplanted in first CR. The 5-year disease-free survival among those transplanted in first CR, those with donors not transplanted in first CR, and those less than age 50 without donors was 41, 42, and 29%, respectively (P = 0.60). A total of 150 eligible patients were randomized to receive late intensification alone or late intensification plus monthly maintenance. In multivariate analyses, treatment with maintenance was associated with prolonged disease-free survival (P = 0.028), but not improved overall survival (P = 0.27). Factors associated with improved overall survival included younger age, lower white blood count (WBC) at diagnosis, having leukemia of M3 morphology, and being of white race. In this study, a diagnosis of M3 AML was particularly favorable, with disease-free and overall survivals of 75 and 56%, respectively, at 7 years.

Trial of oral physostigmine in amyotrophic lateral sclerosis

We evaluated a double-blind, placebo-controlled, and double-crossover trial of oral physostigmine salicylate for a 9-month period in 13 of 25 patients with sporadic amyotrophic lateral sclerosis (ALS). A large dropout rate of 48% was secondary to eight deaths and four exclusions attributed to the incapability to swallow the tablets (physostigmine) and capsules (lecithin) or to attend the clinic. Parameters used for assessment of the drug efficacy included body weight, ALS score, Jamar grip strength, forced vital capacity, and maximum voluntary ventilation. It revealed slight benefit in reduced loss of grip strength compared with the pretrial and placebo periods. However, the rates of decline for body weight, ALS score, forced vital capacity, maximum voluntary ventilation, and megascore did not differ significantly between the pretrial, placebo, and physostigmine periods. We therefore concluded that overall no significant alteration in the clinical course was gained by oral physostigmine therapy in the 13 patients with ALS who were included in this study.

The 47-kD fragment of talin is a substrate for protein kinase P

This laboratory has been characterizing protein serine/threonine kinase reactions of hematopoietic tissues, whose most distinguishing characteristics in vitro are stimulation with vesicular phosphatidyl glycerol, and the ability to function using Mn2+ as the sole divalent cation. The major protein substrates are a 73-kD protein and a protein migrating near ovalbumin on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The 47-kD protein was partially purified from cells harvested by leukapheresis from a patient with acute myelogenous leukemia, using ammonium sulfate precipitation and ion exchange chromatography. This partially purified ion-exchange fraction contained an endogenous kinase activity with characteristics similar to those we previously described of protein kinase P (protein kinase, phospholipid-stimulable: PK-P), but not typical of any form of protein kinase C (PK-C). With longer phosphorylation, the 47-kD band showed increasingly lower mobility demonstrable both by Coomassie blue staining and autoradiography, suggesting both that it was multiply phosphorylated, and that the excisable band was pure. The protein was thus eluted from preparative gel slices and digested with endoproteinase lys C. Sequence data from the fragments identified the protein as the 47-kD calpain fragment of talin, a protein found in focal adhesion plaques and some cell-cell contacts. PK-C phosphorylated the 47-kD protein, as has been reported previously, and phosphopeptide mapping disclosed a similar pattern of phosphorylation using either PK-C or the endogenous activity. The 47-kD protein labeled with the endogenous kinase contained predominantly phosphoserine, with some phosphothreonine and a trace of phosphotyrosine. Intact, purified talin was also phosphorylated by PK-P in a phospholipid-stimulable manner, but at 1/20 the rate of the 47-kD fragment.

Onset, natural history and outcome in idiopathic adult motor neuron disease

Cases of adult-onset idiopathic motor neuron disease (MND) identified from January 1970 through December 1986 were studied in a defined area of California. The patients were followed prospectively throughout the illness in 99% of cases. Among 708 cases aged 25-74 years at onset, the most common type (86%) was typical, sporadic amyotrophic lateral sclerosis (SporALS). The risk of bulbar onset and shorter survival times increased with age in both men and women. About 4%, mainly younger men, experienced unusually long courses with milder paralysis, but could not be identified early in the illness. They probably represent one extreme of the ALS spectrum rather than a distinct subtype. Familial ALS (FamALS) was diagnosed in 7%. It developed earlier in life but ran a slightly longer course, which suggests a different disease process. Overall there was a statistically significant predominance of males, especially in 17 cases (2%) of progressive muscular atrophy (PMA). There were 26 cases (4%) classified as primary lateral sclerosis (PLS). Progressive bulbar palsy was not found; that diagnosis usually denotes merely the bulbar onset of ALS.

A phase I trial of combination fludarabine monophosphate and chlorambucil in chronic lymphocytic leukemia: a Southwest Oncology Group study

Fludarabine monophosphate is a new antimetabolite with demonstrated activity in chronic lymphocytic leukemia (CLL). We have investigated the practicality of utilizing fludarabine in combination with chlorambucil in a disease-specific phase I trial. Twenty-one patients with advanced and previously treated, relapsed or refractory CLL were treated with chlorambucil plus fludarabine. Chlorambucil was given day 1 at 15 or 20 mg/m2 per os and fludarabine days 1-5 at 10, 15, or 20 mg/m2 intravenously, every 28 days. We concluded that with chlorambucil 15 mg/m2, the maximum tolerated dose for fludarabine was 20 mg/m2 in this patient population with this scheduling. Dose-limiting toxicity was thrombocytopenia. A low incidence of peripheral neuropathy, rash, pulmonary fungal infection, and acute tumor lysis syndrome was also encountered. Although responses were observed, it was impossible from this study to determine whether the combination was better than fludarabine alone in this heavily pretreated population. This study does, however, demonstrate the feasibility of exploring the utility of such a combination in previously untreated patients. An intergroup phase III trial utilizing this combination has been initiated.

The type B receptor for tumor necrosis factor-alpha mediates DNA fragmentation in HL-60 and U937 cells and differentiation in HL-60 cells

Tumor necrosis factor-alpha (TNF) binds to two specific cell surface receptors, types A and B, which are both present on HL-60 and U937 cells, and induces monocytoid differentiation in HL-60 cells and early DNA fragmentation in HL-60 and U937 cells. To further define the receptors' roles, we studied how monoclonal antibodies (MoAbs) against each receptor affected TNF-induced cellular responses. HTR-9, an MoAb against the type B (low affinity, 55 Kd) receptor, reproduced all of these effects in a dose-dependent manner. UTR-1, an MoAb against the type A (high affinity, 75 Kd) receptor, had no effect in saturating doses, but supersaturating doses enhanced DNA fragmentation threefold. TNF and interferon gamma (IFN-gamma) synergistically induced morphologic differentiation and monocytic antigen expression, while the antitype B receptor MoAb was synergistic for morphologic response, but not antigen expression. Our results indicate that (1) the type B receptor mediates some responses to TNF in HL-60 and U937 cells, (2) the type A receptor does not stimulate these responses, (3) the TNF molecule is not necessary for some of these actions, and (4) TNF-induced morphologic changes and surface antigen expression in HL-60 cells may be regulated by separate postreceptor pathways.

Induction of differentiation by tumour necrosis factor in HL-60 cells is associated with the formation of large DNA fragments

The DNA fragmentation induced by tumor necrosis factor (TNF) of differentiable human myeloid leukemic HL-60 cells has been further characterized. TNF increased the appearance of very high molecular weight DNA fragments detected by agarose gel electrophoresis. The use of pulsed-field gel electrophoresis (PFGE) revealed these fragments to be as high as 200-400 kilobase pairs. The pattern of HL-60 DNA fragmentation contrasted with that of U937 cells, which exhibited lower molecular weight, nucleosome multiple sized fragments, and greater cytotoxicity in response to TNF. The peak increase of fragments from HL-60 occurred between one and two hours of incubation, with TNF concentrations of 10 U/ml or higher, and was inhibitable by 1 mM Zn2+. Southern blotting of these fragments disclosed enrichment for c-myc related sequences compared with control probes including beta-actin and kappa and lambda light chains. Treatment of DNA with NotI or gamma-irradiation, followed by PFGE, disclosed a class of still higher molecular weight DNA, which decreased following TNF treatment, and which was apparently the precursor of the TNF-induced fragments. TNF thus rapidly increases a class of high molecular weight DNA fragments which are enriched for c-myc related sequences and may arise preferentially from higher molecular weight structures which are detectable following linearization by NotI or gamma-irradiation. Such major but non-random alterations in chromatin structure may contribute to TNF-induced monocytoid differentiation of HL-60.

Detection of Bacteroides infection by counter immunoelectrophoresis test

The counterimmunoelectrophoresis (CIE) test using sonicated antigens of Bacteroides fragilis NCTC 2553 and a B. asaccharolyticus strain, standardised in the laboratory yielded a negative result in the 50 normal sera tested, while it was positive in 24 of 34 (71%) patients with infection due to black pigmented bacteroides and in 10 of 15 (67%) with B. fragilis infection. The microagglutination test (MAT) done in parallel showed a positivity of only 44 and 40 per cent respectively. The CIE test done with B. asaccharolyticus antigen was negative in 87 per cent of patients with infection due to B. fragilis whereas MAT showed cross reactivity to a greater extent.

Rapid identification of clinically important bacteroides by coagglutination method

A coagglutination technique using indigenous reagents was applied for the rapid identification of Bacteroides fragilis and the black pigmented bacteroides group, using colony suspensions. All the 58 strains of B. fragilis and 42 strains of black pigmented bacteroides tested could be correctly identified by this method. The specificity of the coagglutination reagent was confirmed by the absence of cross reactivity with the related species of bacteroides, viz., B. distasonis, B. ovatus, B. vulgatus and B. thetaiotaomicron as well as other anaerobic and aerobic bacteria. A panel of four antisera against B. fragilis was required for correct identification of the strains tested, indicating the presence of multiple serotypes. On the other hand, all 42 strains of black pigmented bacteroides tested could be identified, using a single reagent as these strains appeared to have no antigenic type variants.

Folate status of Mexican American, Cuban, and Puerto Rican women

The objective of this study was to estimate the prevalence of low serum and red blood cell (RBC) folate values of Mexican American (MA), Cuban (C), and Puerto Rican (PR) women examined in the Hispanic Health and Nutrition Examination Survey, 1982-1984. Serum and RBC folate were determined for all women aged 18-44 y by use of a radio-assay kit. The percent of women with low serum folate (less than 6.8 nmol/L) was 11.9% for MA, 10.1% for C, and 8.1% for PR. The prevalence of low concentrations of RBC folate (less than 363 nmol/L) was 7.8%, 16.7%, and 13.6% for MA, C, and PR, respectively. The percentages of women with reduced tissue stores of folate were 4.3% for MA, 6.0% for C, and 4.0% for PR. Years of education completed and poverty status did not significantly affect folate concentrations; however, the prevalence of low folate concentrations among users of vitamin or mineral supplements was significantly lower than it was among nonusers in selected subgroups.

Plasma cell dyscrasia: a case of POEMS syndrome with a unique dermatologic presentation

POEMS (polyneuropathy, organomegaly [hepatosplenomegaly or lymphadenopathy], endocrinopathy, M protein, and skin changes) syndrome is an uncommon plasma cell dyscrasia with diverse manifestations, including lymphadenopathy as well as those that comprise the acronym. Dermatologic changes may include hyperpigmentation, thickened skin, hypertrichosis, and papular angiomas. These changes are believed to result from humoral products of the plasma cell clone and frequently resolve with treatment of the neoplasm. We describe a man with typical POEMS syndrome with a unique skin lesion: a large, sharply circumscribed, pigmented plaque on the anterior chest wall centered over a plasmacytoma of the sternum. Results of histologic examination showed a proliferation of capillaries of varying size, enlarged fibroblasts, and increased amounts of collagen and proteoglycan from the dermis to the periosteum. Because the outer cortex of the sternum was eroded, peptide mediators of vascular and fibroblast proliferation may have diffused directly from the plasma cell lesion into the tissues of the chest wall.

Interferon effects upon fluorouracil metabolism by HL-60 cells

In order to better understand the synergistic antiproliferative effects of interferon in combination with fluorouracil (FUra), we studied effects of alpha 2-interferon upon FUra induced inhibition of thymidylate synthase of HL-60 cells. The 50% inhibitory dose for FUra decreased from approximately 75 microM to 10 microM following interferon treatment, as measured by whole cell activity assays. Enhanced FUra inhibition of cytosolic [3H] - FdUMP binding of interferon treated cells was also noted. FdUMP accumulation following FUra treatment increased over 10 fold in interferon treated cells, but dUMP did not increase. These results suggest that interferon can sensitize cells to FUra inhibition of thymidylate synthase by enhancing accumulation of FdUMP.

Tumor necrosis factor induced DNA fragmentation of HL-60 cells

Tumor necrosis factor (TNF) induces differentiation of HL-60 cells, with only slight effects upon proliferation and little or no cytotoxicity. TNF induced cytotoxicity of other target cell lines has been associated with DNA fragmentation. To assess whether TNF-induced DNA fragmentation might also contribute to HL-60 differentiation, studies were performed using a [3H]-dThd release assay. Between 1 and 2 hours of culture, significant [3H]-dThd release was induced by TNF at concentrations of 10 U/ml and greater. This response was blocked by inhibiting energy metabolism, but not by several inhibitors of cell surface signal transduction, protein or RNA synthesis, or free radical scavengers. DNA electrophoresis of the released DNA disclosed a wide range of low molecular weight fragments. It is possible that TNF-induced DNA fragmentation contributes to HL-60 differentiation.

A prospective randomized trial of alpha 2B-interferon/gamma-interferon or the combination in advanced metastatic renal cell carcinoma

Eighty-nine patients with advanced measurable metastatic renal cell carcinoma were entered into a prospective randomized trial comparing alpha-interferon to gamma-interferon and to the combination. The trial was performed in order to confirm the activity of gamma-interferon and assess the potential clinical synergism. Response rates were 5, 10, and 5%, respectively. The low response rate may have been due to the inability to raise the doses of the interferons to higher levels. Clinical synergy at this dose, route, and schedule of administration in renal cell carcinoma does not exist.

Purification and assay of a phosphatidylglycerol-stimulated protein kinase from murine leukemic cells and its perturbation in response to IL-3 and PMA treatment

Protein kinase P (PK-P), which has previously been detected from both human and murine leukemic cells, is characterized by distinctive patterns of phospholipid stimulation and substrate preferences, and is chromatographically separable from protein kinase C (PK-C). We have developed a three-step purification of PK-P from the interleukin 3 (IL-3)-dependent DA-1 murine leukemic cell line, entailing DEAE-Sephacel chromatography followed by TSK-3000 size exclusion and Mono-Q anion exchange HPLC steps. This yielded a 27-kd protein (from sodium dodecyl sulfate polyacrylamide gel electrophoresis) capable of preferentially phosphorylating the characteristic 75.5- and 77-kd endogenous substrates of PK-P previously noted. These observations were the basis for the development of a quantitative assay for PK-P, utilizing its separation from PK-C upon DEAE-Sephacel minicolumns followed by measurement of phosphatidylglycerol-stimulated histone H2B phosphorylation. This assay, and an analogous assay for PK-C, was then used to study the response of IL-3-starved DA-1 cells to IL-3 restimulation. PK-C exhibited cytosol to particulate redistribution following either IL-3 or phorbol 12-myristate 13-acetate (PMA) treatment, as has been previously described by others using similar systems. PK-P exhibited a rapid decrease in total activity following either IL-3 or PMA treatment, suggesting a response to PK-C activation. This was followed by a recovery phase during which PK-P activity slowly increased, with preferential redistribution into the particulate fraction of IL-3- but not PMA-treated cells. This difference in redistribution was thus likely to be under the control of signal transduction events other than PK-C activation. DA-1 PK-P thus exhibits a complex pattern of modulation by IL-3 and PMA, and may therefore constitute a new component of the cellular signal transduction cascade.

Early effects of G- and GM-CSF upon HL-60 proliferation and differentiation

Effects of human recombinant G- and GM-CSF upon HL-60 myeloid leukemic cell differentiation and proliferation have been studied. Minimal morphologically apparent differentiation was noted with treatment up to 7 days and concentrations up to 1000 units/ml. Cell surface marker analysis disclosed modest increases of MO1 and HLA-Dr expression following treatment with G-CSF/GM-CSF, for 2-4 days. Macromolecular synthesis rates following 24-hr exposures to CSF disclosed stimulation of [3H]uridine greater than [3H]thymidine greater than [3H]leucine by GM-CSF only. Proliferation was also assessed by flow cytometric DNA histogram analysis which also disclosed greater increases in the percentage of S + G2/M cells following GM-rather than G-CSF treatment. This study documents subtle early effects of G- and GM-CSF upon HL-60 proliferation and differentiation. Differentiative effects were relatively more marked with G-CSF while proliferative effects were more marked with GM-CSF.

Phosphatidylglycerol-modulated protein kinase activity from human spleen. II. Interaction with phospholipid vesicles

Phosphorylation of endogenous and artificial protein substrates by protein kinase P is stimulated by phosphatidylinositol or phosphatidylglycerol (D. J. Klemm, and L. Elias (1987) J. Biol. Chem. 262, 7580-7585; L. Elias and A. Davis (1985) J. Biol. Chem. 260, 7023-7028). Stimulation of protein kinase P activity required phospholipid vesicles rather than free phospholipid molecules. Protein kinase P activity increased as the phosphatidylinositol content of the vesicles was raised from 20 to 100%; no stimulation was detected below 20% phosphatidylinositol. This suggests that a vesicle surface rich in phosphatidylinositol is required for enzyme activation. Maximum activation of protein kinase P activity showed an optimum value with respect to phospholipid concentration, with both endogenous and artificial protein substrates. The phospholipid concentration at which optimal enzyme activity occurred shifted in response to the concentration of protein substrate, but not enzyme concentration. Therefore, the density of substrate molecules on the surface of phospholipid vesicles is a critical feature of protein kinase P stimulation. Binding of protein kinase P to vesicles was independent of micelle composition, but the binding of the artificial substrate, histone H2B, was specific for vesicles containing phosphatidylinositol or phosphatidylglycerol, and increased as the content of phosphatidylinositol was increased. Thus, an important feature of protein kinase P activation appeared to be the specific binding of protein substrate to phospholipid vesicles.