Biomedical subjects

M Andreeff

Publications and source records attributed to M Andreeff.

At least 127 records · Page 7Linked to original sources

PubMed1996

A new series of vitamin D analogs is highly active for clonal inhibition, differentiation, and induction of WAF1 in myeloid leukemia.

The active form of vitamin D3 [1 alpha, 25-dihydroxyvitamin-D3 (1 alpha, 25(OH)2D3)] modulates the proliferation and differentiation of hematopoietic cells. Analogs of 1 alpha, 25(OH)2D3 that have greater potency may have the potential as adjuvant therapy for high-risk patients in remission for acute myelogenous leukemia (AML) and myelodysplastic syndromes. A new generation of 11 analogs of 1 alpha, 25(OH)2D3 has been synthesized, and we examined their effects on the human leukemic cell line HL-60. This cell line provides a sensitive monitor of activity of the 1 alpha, 25(OH)2D3 analogs. All the compounds were potent, producing a 50% clonal inhibition (ED50) in the range of 10(-8) to 10(-11) mol/L; nine of the 11 analogs had ED50s at concentrations that were at least 10-fold lower than those for the parental 1,25(OH)2D3. The most active compound [cmpd LA, (22R)-1 alpha, 25-(OH)2-16,22,23-triene-D3] had an ED50 of 2 x 10(-11) mol/L; it was also tested on clonogenic cells from patients with AML, and it achieved an ED50 of approximately 6 x 10(-11) mol/L, while 1 alpha, 25(OH)2D3 produced an ED50 of approximately 10(-8) mol/L on the same population of cells. Five different cell surface markers were examined on HL-60 cells exposed to the 1 alpha, 25(OH)2D3 analogs: HLA-DR and CD11b were induced by all of the compounds; CD13 was induced by six of the 12 compounds, including 1,25(OH)2D3; CD14 was strongly induced by all compounds; and CD38 was induced rather weakly by nine of 12 analogs. WAF1/CIP1/p21, a cyclin-dependent kinase inhibitor (CDKI), which is important in blocking the cell cycle, was examined by Western blot and was found to be induced by all of the compounds, suggesting a possible mechanism by which these analogs inhibit leukemic growth. The induction of WAF1 occurred at concentrations of vitamin D analogs as low as 10(-10) mol/L. This structure-function study showed that a new series of 1 alpha, 25(OH)2D3 analogs was active in clonal inhibition, as well as induction of differentiation and WAF1 expression of HL-60 cells. The key structural motifs included C-16 double bond, double and/or triple bonds in the side chain, lengthening of the side chain, 20-epi-conformation of the side chain, replacement of six hydrogens at the end of the side chain with fluorines, and the removal of C-19. Consideration should be given to further in vivo testing of toxicity and efficacy to move toward a clinical trial, especially in a setting of minimal residual disease.

Animals↗

PubMed1996

Involvement of P-glycoprotein in the transmembrane transport of interleukin-2 (IL-2), IL-4, and interferon-gamma in normal human T lymphocytes.

The physiological role of the multidrug resistance P-glycoprotein (P-gp), which is expressed by normal human T lymphocytes, is still largely unknown. To investigate whether or not P-gp is involved in the transport of cytokines, peripheral blood lymphocytes were stimulated with phytohemagglutinin (PHA) in the absence or presence of P-gp inhibitors, and concentrations of cytokines (interleukin-2 [IL-2], IL-4, IL-6, interferon-gamma [IFN-gamma]) in the supernatants of these cultures were quantitated by enzyme-linked immunosorbent assay. P-gp inhibitors included verapamil (Ver), tamoxifen (Tmx), and the P-gp specific monoclonal antibody UIC2. Release of IL-2 was significantly suppressed by these inhibitors at concentrations that were also effective in blocking efflux of Rhodamine-123 from normal T lymphocytes. IL-2 mRNA expression in lymphocytes was not different between PHA control and the cultures with P-gp inhibitors. Ver and Tmx did not interfere with T-cell activation as determined by CD25 and CD69 expression. In a nonhematological model, the P-gp expressing HCT-8 adenocarcinoma cell line, exogenously added IL-2 was shown to exert an inhibitory effect on P-gp mediated Rhodamine-123 efflux. In addition, transepithelial transport of IL-2 by electrophysiologically tight and polarized HCT-8 monolayers was examined. A time-dependent flux of IL-2 across dense monolayers, which was partially inhibited by Ver, was observed. We also investigated whether or not P-gp inhibitors suppressed release of other cytokines produced by activated T cells (IL-4, IL-6, IFN-gamma). Release of IL-4 and IFN-gamma was significantly inhibited by Ver, Tmx, and UIC2; however, release of IL-6 remained unaffected. These data show P-gp mediated transmembrane flux of IL-2 in T lymphocytes and HCT-8 cells. We conclude that P-gp participates in the transport of cytokines (IL-2, IL-4, and IFN-gamma) in normal peripheral T lymphocytes.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

The novel anthracycline annamycin is not affected by P-glycoprotein-related multidrug resistance: comparison with idarubicin and doxorubicin in HL-60 leukemia cell lines.

A major factor in limiting the efficacy of anthracyclines is overexpression of the MDR1-encoded p-glycoprotein (p-gp). A new analogue less affected by p-gp is annamycin (ANN), an anthracycline antibiotic with high affinity for lipid membranes and significantly more activity than doxorubicin (DOX). We investigated whether ANN was affected by p-gp-mediated multidrug resistance (MDR) by comparing the cellular accumulation and retention of ANN, idarubicin (IDR), and DOX in the p-gp-negative human leukemia cell lines (HL-60S) and its DOX-selected p-gp-positive subline (HL-60/DOX) with and without verapamil (VER). As expected, HL-60/DOX cells showed lower DOX uptake than HL-60S cells; coincubation with VER (10 mmol/L) increased uptake 2.6-fold restoring it to 100% of uptake in HL-60S cells. IDR uptake increased 1.5-fold in the presence of VER, but ANN was not affected. Coincubation with VER increased DOX retention in HL-60/DOX cells 2.8-fold and IDR retention 1.4-fold; unchanged ANN retention indicated that ANN may overcome p-gp. In the cytotoxicity assay to correlate intracellular anthracycline content with antitumor activity, we found ANN to be less potent than DOX and IDR In sensitive cells, ID 50 being the drug concentration that inhibits cell growth by 50% but its resistance index (RI; ID50 resistant cells divided by ID50 sensitive cells) was lower than that of IDR and DOX (2.6 v 40 and 117.5). Coincubation in the presence of VER resulted in 4.5-fold and 2-fold RI decreases of DOX and IDR, respectively, whereas ANN did not change, further confirming ANN's ability to circumvent p-gp-mediated MDR. Confocal microscopy studies of IDR, ANN, and DOX showed higher intracellular drug compartmentalization for DOX in HL-60/DOX cells incubated in the presence of VER. This study provided evidence that, unlike DOX and IDR, ANN is not affected by p-gp-mediated MDR.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

Methods to detect P-glycoprotein-associated multidrug resistance in patients' tumors: consensus recommendations.

Multidrug resistance (MDR), especially that associated with overexpression of MDR1 and its product, P-glycoprotein (Pgp), is thought to play a role in the outcome of therapy for some human tumors; however, a consensus conclusion has been difficult to reach, owing to the variable results published by different laboratories. Many factors appear to influence the detection of Pgp in clinical specimens, including its low and heterogeneous expression; conflicting definitions of detection end points; differences in methods of sample preparation, fixation, and analysis; use of immunological reagents with variable Pgp specificity and avidity and with different recognition epitopes; use of secondary reagents and chromogens; and differences in clinical end points. Also, mechanisms other than Pgp overexpression may contribute to clinical MDR. The combined effect of these factors is clearly important, especially among tumors with low expression of Pgp. Thus, a workshop was organized in Memphis, Tennessee, to promote the standardization of approaches to MDR1 and Pgp detection in clinical specimens. The 15 North American and European institutions that agreed to participate conducted three preworkshop trials with well-characterized MDR myeloma and carcinoma cell lines that expressed increasing amounts of Pgp. The intent was to establish standard materials and methods for a fourth trial, assays of Pgp and MDR1 in clinical specimens. The general conclusions emerging from these efforts led to a number of recommendations for future studies: (a) although detection of Pgp and MDR1 is at present likely to be more reliable in leukemias and lymphomas than in solid tumors, accurate measurement of low levels of Pgp expression under most conditions remains an elusive goal; (b) tissue-specific controls, antibody controls, and standardized MDR cell lines are essential for calibrating any detection method and for subsequent analyses of clinical samples; (c) use of two or more vendor-standardized anti-Pgp antibody reagents that recognize different epitopes improves the reliability of immunological detection of Pgp; (d) sample fixation and antigen preservation must be carefully controlled; (e) multiparameter analysis is useful in clinical assays of MDR1/Pgp expression; (f) immunostaining data are best reported as staining intensity and the percentage of positive cells; and (g) arbitrary minimal cutoff points for analysis compromise the reliability of conclusions. The recommendations made by workshop participants should enhance the quality of research on the role of Pgp in clinical MDR development and provide a paradigm for investigations of other drug resistance-associated proteins.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

A pilot study of high-dose interleukin-3 treatment of relapsed follicular small cleaved-cell lymphoma: hematologic, immunologic, and clinical results.

The growth stimulatory effects of interleukin-3 (IL-3) on normal hematopoietic progenitor cells are well established, and clinical trials using IL-3 after bone marrow transplantation for various malignancies including lymphomas are frequently conducted. Although the IL-3 receptor is expressed on the surfaces of follicular small cleaved-cell lymphoma (FSCCL) cells, the in vivo effects of IL-3 on FSCCL have not been studied previously. Because our preclinical data suggested that IL-3 may have dose-dependent inhibitory effects on FSCCL cells in vitro, we treated eight FSCCL patients with high-dose IL-3 in an outpatient setting. Each patient received 1 mg/m2 of IL-3 subcutaneously daily for 14 days followed by 7 days without IL-3. After three courses (9 weeks), the patients were evaluated for clinical responses. One patient had a minor response, and four had no responses. Three patients who had progressive disease before IL-3 treatment continued to have progressive disease. In two patients with bone marrow involvement with lymphoma, IL-3 had no effect on FSCCL cells. One patient with peripheral blood involvement with FSCCL cells that expressed IL-3 receptors had temporary growth arrest of the circulating malignant cells. IL-3 significantly increased the absolute neutrophil count in seven patients (87%) but had little effect on the number of normal circulating B cells. There was an increase in the number of circulating natural killer cells and CD8+ cells in four patients. Treatment was very well tolerated; no life-threatening toxicities were observed. The most common toxicities were injected conjunctivae (100%), fever (100%), fatigue (87%), and skin rash (75%). Most of the side effects subsided with the continued use of IL-3. These preliminary results suggest that high-dose IL-3 does not stimulate the growth of FSCCL cells in vivo and, in some instances, may cause growth inhibition.

Aged↗

PubMed1996

Cellular uptake and localization of liposomal-methylphosphonate oligodeoxynucleotides.

Nuclease digestion and intracellular delivery are major factors limiting the potential use of oligodeoxynucleotides as antisense molecules. Structural analogues of phosphodiester oligodeoxynucleotides, such as phosphorothioates and methylphosphonates, are resistant to nuclease degradation and can still bind to their mRNA targets. However, their limited ability to escape from the endosomal/lysosomal compartments and reach the intracellular sites of action have dampened their potential clinical application. To circumvent this problem we have incorporated methylphosphonate oligodeoxynucleotides into liposomes. We found that the level of uptake of liposome-incorporated methylphosphonate oligodeoxynucleotides is time and concentration dependent. Maximal up take occurred at 8 h when 4-8 microM liposome-incorporated methylphosphonate oligodeoxynucleotides was added. Approximately 50% of liposome-incorporated methylphosphonate oligodeoxynucleotides were retained in cells after 24 h of incubation. Using fluorescent microscopy, intracellular fluorescence could be seen within 2.5 h of incubation. Diffused fluorescence was found throughout the cytoplasm, suggesting that the liposome-incorporated methylphosphonate oligodeoxynucleotides were not confined within the endosomal/lysosomal structures. We conclude that liposomes can effectively deliver methylphosphonate oligodeoxynucleotides to the cytoplasm, which is the major intracellular site of action for translational arrest.

Drug Carriers↗

PubMed1996

Cell kinetic analysis of intact rat colonic crypts by confocal microscopy and immunofluorescence.

BACKGROUND & AIMS: Precise quantitative and spatial analysis of cell cycle-related biomarkers in colonic crypts is often vital for studies of colon carcinogenesis and cancer prevention. To overcome the limitations of histology, confocal laser microscopy of microdissected whole crypts was used to quantitate S phase and mitotic cells. METHODS: Microdissected distal colonic crypts were studied in a modified rat starvation refeeding model. S phase cells were labeled in vivo with 5-bromodeoxyuridine. Mitotic cells were labeled with MPM2 (antibody to mitosis-specific epitope) and also assessed for chromatin morphology with propidium iodide. Sequential optical crypt sections, produced by confocal microscopy, were digitally imaged. S phase labeling indices per whole crypt were also compared with those derived by conventional immunohistochemistry. RESULTS: S phase and mitotic cells were clearly discriminated without background staining. The labeled S phase cell number and fraction per whole crypt were significantly decreased with starvation and increased with refeeding. Variability in the labeling index between whole crypts analyzed by confocal microscopy was significantly smaller than between histological crypt sections. Consequently, the intervention contributed to 92.2% of the total variability of the labeling index in whole crypts but only to 59% of the variability in histological sections. CONCLUSIONS: Major limitations of histology are overcome by crypt microdissection and confocal microscopic analysis. The total crypt cell population as well as labeled M phase and S phase cells can be imaged, localized, and quantitated with improved precision.

Animals↗

PubMed1996

CD30 ligand is expressed on resting normal and malignant human B lymphocytes.

CD30, a member of the tumour necrosis receptor superfamily, is physiologically expressed on a subpopulation of T helper cells in normal individuals but is also expressed on several malignant and virally transformed cells. Its ligand (CD30L) is a pleiotropic cellular transmembrane protein that can induce cell death in several CD30+ cell lines. CD30L expression has been reported on activated human peripheral blood T lymphocytes and macrophages but not on B cells. Here we show that the CD30L is expressed on resting normal and on malignant B cells in addition to both CD4+ and CD8+ subsets of activated T cells, making it the second tumour necrosis family member, in addition to the CD27 ligand, that can be expressed on both T and B cells. These findings raise the possibility that the CD30L has a role in B-cell/T-cell communication and that B and T cells are likely to be involved in the growth regulation of CD30+ tumours.

B-Lymphocytes↗

PubMed1996

Semi-automated PCR method for quantitating MDR1 expression.

The MDR1 gene is involved in drug resistance in many hematopoietic and solid tumors. The Quantitative PCR System 5000 (QPCR-5000; Perkin-Elmer) is a new instrument system that uses electrochemiluminescence to automatically quantitate polymerase chain reaction (PCR) products. A comparative study between radioactively labeled PCR (32P-PCR) and QPCR was performed to analyze the MDR1 gene expression in the drug-resistant (Doxorubicin) cell lines Dox40, Dox6, the parental cell line 8226/S, CEM Dox1 and three acute myeloid leukemia (AML) patient samples. Using the Dox40 and Dox6 resistant cell lines, we compared the sensitivities of QPCR and 32P-PCR. A strong signal was obtained from QPCR at 20 to 25 cycles (which is in the linear range for quantitation), while a weak signal was obtained using 32P-PCR at the same cycle number. Dilution experiments gave better precision with the QPCR than with the radioactive method. AML samples were studied with the MDR1-specific MAbs MRK16 and 4E3, and the efflux function was analyzed using Rh-123 retention in the absence or presence of verapamil. The three samples showed high (D = 0.79), medium (D = 0.52) and negative (D = 0.08) p-glycoprotein (P-gp) levels and correlated with efflux function. The MDR1/beta 2-M mRNA ratios for 32P-PCR were 0.41, 0.40 and 0.12, respectively, and were 0.127, 0.097 and 0.028, respectively, for QPCR. There were significant differences between the samples with high and medium P-gp levels comparing the two methods. Very low levels of MDR1 in CEM Dox1 cells could be detected only by QPCR. In conclusion, QPCR was found to be more reproducible, accurate and sensitive than 32P-PCR.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

Disseminated intravascular coagulation in adult acute lymphoblastic leukemia: frequent complications with fibrinogen levels less than 100 mg/dl.

In order to establish the frequency and clinical complications of DIC during remission induction of untreated adults with acute lymphoblastic leukemia, we retrospectively reviewed the records of 125 consecutive patients treated with vincristine, doxorubicin, and dexamethasone but without L-asparaginase. DIC, defined as hypofibrinogenemia in the presence of elevated fibrin-fibrinogen degradation products, was detected at presentation in 10% of 99 and during remission induction in 67% of 58 patients who were screened for DIC. Elevated levels of D-dimers (DD) were seen in all eight patients with DIC in whom they were measured. All cases of DIC were diagnosed by the ninth day of induction and were associated with infection in 15 of 39 patients. DIC did not cause any deaths but was temporally associated with two thromboses and four hemorrhages in six of the 16 patients with fibrinogen levels < 100 mg/dl but with only one hemorrhage among 23 patients (4%) with fibrinogen levels > 100 mg/dl (P < 0.01). Heparin was not administered to any patient, whereas platelets were administered to all to maintain platelet counts > 20 x 10(9)/l. Fresh frozen plasma (FFP) and/or cryoprecipitate were administered 26 patients resulting in a contemporaneous correction of the coagulopathy and in control of hemorrhages and thromboses. We conclude that DIC is rare at presentation but common during induction of adult ALL and is frequently associated with clinical complications when fibrinogen levels are < 100 mg/dl. We recommend daily testing of fibrinogen, PT, and DD during the first 10 days of induction, and for the patients with DIC platelet transfusions to maintain counts > 20 x 10(9)/l, and when fibrinogen levels fall below 100 mg/dl transfusions of FFP and/or cryoprecipitate. Additional studies are needed to determine the optimal management of the DIC during remission induction of adult acute lymphoblastic leukemia.

Adult↗

PubMed1996

Acute lymphoblastic leukemia following preleukemic syndromes in adults.

Preleukemic syndromes (PLS) evolve to acute myeloid leukemia (AML) in 15-50% of cases, but rarely transform to acute lymphoblastic leukemia (ALL). AML following preleukemic syndromes has a poor prognosis, but little is reported about the outcome of secondary ALL. From the adult leukemia database at MD Anderson Cancer Center, nine patients with ALL following myelodysplastic syndrome (MDS) (n=6), smoldering leukemia (n=1), or cytopenias with dysplastic features (n=2) were identified. Clinical and laboratory features were abstracted from the database, patient charts, review of the bone marrows and special laboratory studies. The median interval from diagnosis of PLS to ALL was 6 months. Blasts with lymphoid morphology and terminal deoxynucleotidyltransferase (TdT) and periodic acid Schiff (PAS) staining were present in eight of nine cases and four of six cases respectively. T cell and myeloid markers were expressed in the majority of cases, but T cell gene rearrangements were not detected. Only one patient had electron microscopic myeloperoxidase-positive staining. Two patients later transformed to AML. Patients were predominantly male (89%) with a median age of 69 years. The complete remission (CR) rate with ALL-directed chemotherapy (78%) was comparable to that of other adult ALL patients (74%) (n=327) without excess myelosuppression. Marrow dysplasia persisted in CR in three of seven cases. The median remission duration of 16 months (range 4.5 to 51+ months) and the median overall survival of 21 months (range 1 to 55+ months) were comparable to that of ALL patients overall. ALL following preleukemic syndromes is a distinct syndrome with T cell and myeloid markers and responds well to ALL-directed therapy. The presence of myeloid and lymphoid markers suggests the transformation of an early stem cell.

Adult↗

PubMed1996

Activation of retinoid receptors RAR alpha and RXR alpha induces differentiation and apoptosis, respectively, in HL-60 cells.

Induction of granulocytic differentiation in HL-60 myeloid leukemia cells by retinoids is followed by their death via apoptosis. Retinoids are known to mediate their biological effects through at least two distinct types of nuclear receptors, the retinoic acid receptors and retinoid X receptors. We undertook to characterize the potential role of these receptors in inducing differentiation and apoptosis by retinoids. For this, we used a previously described variant of an HL-60 cell line (HL-60R) in which retinoid receptor function has been abrogated due to a trans-dominant negative mutation. Retroviral vector-mediated gene transfer was used to introduce the normal retinoic acid receptor (RAR alpha) or retinoid X receptor (RXR alpha) into HL-60R cells. Our results suggest that ligand-induced activation of RAR alpha is sufficient to induce differentiation in HL-60 cells, whereas activation of RXR alpha can induce direct apoptosis of these cells without their prior commitment to differentiate.

ADP-ribosyl Cyclase↗

PubMed1996

Graft-versus-leukemia effect after allogeneic bone marrow transplantation for chronic lymphocytic leukemia.

We report the case of a patient with chronic lymphocytic leukemia (CLL) with persistent lymphocytosis and lymphadenopathy after allogeneic bone marrow transplantation (BMT). After receiving a donor lymphocyte infusion on day 87 he achieved complete remission upon development of chronic graft-versus-host disease, suggesting that a graft-versus-leukemia effect is operative in this malignancy.

Adult↗

PubMed1996

Induction of death (CD95/FAS), activation and adhesion (CD54) molecules on blast cells of acute myelogenous leukemias by TNF-alpha and IFN-gamma.

Leukemic growth is determined by the balance of cell proliferation, differentiation and cell death. In vitro, the blasts of acute myelogenous leukemia (AML) proliferate under the influence of certain positive and negative regulators (cytokines). We conducted this study to determine whether cytokines could induce markers of cell death (FAS/Apo-1/CD95), of cell activation (HLA-DR) and cell adhesion (ICAM-1, CD54) in AML cell lines and primary AML samples. As inducers, tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma were chosen. At baseline, CD95 and CD54 were weakly and HLA-DR was strongly expressed. CD95 was induced by TNF in 6/12 myeloid leukemia cell lines, and by IFN in 9/12 cell lines. Taken together, CD95 was upregulated by at least one cytokine in 11/12 cell lines. HLA-DR was inducible in 10/12 cell lines, with IFN being more potent than TNF. CD54 showed the strongest induction: TNF resulted in a more than 20-fold induction in positive cell lines, and IFN resulted in a more than 20-fold induction. In primary AML samples, CD95 was induced in 14/14 samples examined, with TNF being more potent than IFN. HLA-DR expression was increased by IFN in 12/15 samples and by TNF in 11/13 samples. The inducibility of HLA-DR by IFN was inversely correlated with baseline expression. As in the cell lines, CD54 was induced in most cases of AML. In addition to the induction of surface markers by cytokines, the culture of leukemia cells with fetal calf serum increased the expression of these markers, especially CD95 and CD54. Our results demonstrate that CD95 is not downregulated when TNF binds to its receptors, but is induced in cell lines and patient samples. Despite the induction of expression of CD95 (all cases of AML and most cell lines), 7/8 myelogenous leukemia lines and 6/7 patient samples remained resistant to CD95 triggering by antibody or by CD95 ligand, which suggests a lesion in normal cell signaling. As a positive control, a T-cell line (Jurkat) with 60% to > 90% apoptotic cells after a 22 h incubation was used. The number of CD95-binding sites was not correlated with the induction of apoptosis. The resistance of most cases of AML to CD95 triggering despite inducible expression may also be related to leukemia-specific antagonists of CD95 signal transduction, and requires further investigation. Altogether, our results indicate that surface markers related to apoptosis, activation and adhesion can be induced on AML blasts, and could be relevant to treatment strategies that exploit ligand binding to these surface epitopes.

Adult↗

PubMed1996

Telomerase activity in human acute myelogenous leukemia: inhibition of telomerase activity by differentiation-inducing agents.

The terminal regions of human chromosomes, the telomeres, shorten with each cell division in most normal somatic cells. Telomerase, a ribonucleoprotein that synthesizes telomeric DNA onto chromosomal ends, is activated in germline cells and almost all tumor cells. Telomerase activity maintains the stability of telomere length, resulting in indefinite cellular proliferation (immortality). In the present study, telomerase activity was analyzed in leukemic mononuclear blood cells obtained from 56 patients with acute myelogenous leukemia (AML) with known cytogenetic alterations. Heterogenous levels of telomerase activity were observed and generally correlated with cytogenetic status. Patients with 11q abnormalities and -5/-7 (unfavorable cytogenetics) tended to have high telomerase activity compared with cells obtained from AML patients with other types of cytogenetics. Additional studies with a larger cohort of patients will determine whether these differences are statistically significant. Chemotherapy agents that result in differentiation of leukemic cells also resulted in inhibition of telomerase activity. Knowledge of telomerase activity in patients with AML, before and throughout therapy, may have clinical utility for following disease progression and may predict early cancer relapse.

Adult↗

PubMed1995

Activation of p21WAF1/Cip1 expression by a temperature-sensitive mutant of human p53 does not lead to apoptosis.

The cyclin-dependent kinase inhibitor p21WAF1/Cip1 (p21) inhibits cellular proliferation and has been implicated in p53-dependent apoptosis. In this study, we examined the regulation of p21 in the K562 erythroleukemia cell line using a human temperature-sensitive mutant of p53, 143Ala. We showed that 143Ala at the permissive temperature (32 degrees C) activated the expression of p21. Stable cell lines expressing 143Ala or other p53 mutants were established. We then examined whether elevation of p21 promotes apoptosis and sensitized cells to radiation-induced apoptosis. Our results showed that p21 elevation did not promote or sensitize K562 cells to apoptosis.

Apoptosis↗

PubMed1995

Myeloid markers in adult acute lymphocytic leukemia. Correlations with patient and disease characteristics and with prognosis.

BACKGROUND: The expression of myeloid markers on lymphoblasts has been associated with adverse outcome in acute lymphocytic leukemia (ALL). The purpose of the study was to analyze the experience with adults treated at the University of Texas M. D. Anderson Cancer Center with myeloid marker- (MY) positive ALL in relation to patient and disease characteristics, response to therapy, and prognosis. METHODS: Since 1988, 64 of 162 adults (40%) with newly diagnosed ALL referred to our service had MY-positive ALL. Their characteristics and outcomes were compared with the 98 patients with MY-negative ALL. Patients were treated with the vincristine-doxorubicin-dexamethasone (VAD) regimens. RESULTS: Patients with MY-positive ALL were significantly older (median ages, 47 years vs. 33 years; P = 0.03), had a higher incidence of CD34 antigen expression (59% vs. 36%; P < 0.01), and a lower incidence of common acute leukemia antigen expression (50% vs. 71%; P < 0.01), serum alkaline phosphatase elevation (58% vs. 83%; P < 0.01), and thrombocytopenia at diagnosis (49% vs. 69%; P = 0.02). Myeloid marker positivity, as expected, was significantly higher in null cell ALL (82%), and significantly lower in mature B-cell ALL (17%) (P < 0.01). Forty-one of 64 MY-positive patients achieved complete remission (CR) after induction therapy compared with 76 of 98 patients MY-negative disease (CR rate 64% vs. 78%; P = 0.06). With a median follow-up of 45 months, no statistical differences were observed in remission duration or survival between MY-positive and MY-negative patients, overall, and within immunophenotypic subsets (T-cell vs. others), or among subgroups with single marker (CD13, CD14, CD33, CD34) positivity. The 3-year remission duration rates were 32% for MY-negative and 40% for MY-positive patients (P not significant), and 3-year survival rates were 26% and 31%, respectively (P not significant). CONCLUSIONS: With VAD therapy, myeloid marker positivity is not associated with significant differences in prognosis in adult ALL.

Adolescent↗

PubMed1995

Homoharringtonine therapy induces responses in patients with chronic myelogenous leukemia in late chronic phase.

Homoharringtonine (HHT) is a plant alkaloid with potent myelosuppressive activity and little toxicity when used in a continuous infusion schedule. The antileukemic efficacy of HHT has been shown in acute myeloid leukemia, but has not been investigated in chronic myelogenous leukemia (CML). Seventy-one patients with Philadelphia chromosome-positive (Ph+) CML in late chronic phase (time from diagnosis to therapy longer than 12 months) were treated with a continuous infusion of HHT at a daily dose of 2.5 mg/m2 for 14 days for remission induction and for 7 days every month for maintenance. The median number of courses given was 6 (range, 1 to 35) and 21 patients (30%) continue on treatment. Forty-two of 58 patients (72%) evaluable for hematologic response achieved a complete hematologic remission, and 9 (16%) had a partial hematologic remission. Twenty-two of 71 patients (31%) developed a cytogenetic response; it was major (Ph+ cells less than 35%) in 11 (15%) and complete (Ph+ cells 0%) in 5 (7%). Significant myelosuppression occurred in 39% of induction courses and 9% of maintenance courses. Fever or documented infection was present in 26% of induction courses and in only 8% of maintenance courses. Nonmyelosuppressive toxicity was minimal. Homoharringtonine produced hematologic remissions in the majority of patients with advanced chronic-phase CML. Cytogenetic response occurred in some patients without an association with myelosuppression, and these responses may be prolonged. Future studies investigating homoharringtonine in combination with other active agents in CML, such as interferon, are warranted.

Adult↗