Acute Myelogenous Leukemia Cells Secrete Factors that Stimulate Cellular LDL Uptake via Autocrine and Paracrine Mechanisms.

Leukemic cells isolated from most patients with acute myelogenous leukemia (AML) have higher low density lipoprotein (LDL) uptake than normal mononuclear blood cells. Little is known, however, about the mechanism behind the elevated LDL uptake. We investigated if AML cells secrete factors that stimulate cellular LDL uptake.

Anti-leukaemic effects induced by APR-246 are dependent on induction of oxidative stress and the NFE2L2/HMOX1 axis that can be targeted by PI3K and mTOR inhibitors in acute myeloid leukaemia cells.

The small molecule APR-246 (PRIMA-1(MET) ) is a novel drug that restores the activity of mutated and unfolded TP53 protein. However, the mechanisms of action and potential off-target effects are not fully understood. Gene expression profiling in TP53 mutant KMB3 acute myeloid leukaemia (AML) cells showed that genes which protected cells from oxidative stress to be the most up-regulated.

Targeting p53 in vivo: a first-in-human study with p53-targeting compound APR-246 in refractory hematologic malignancies and prostate cancer.

Purpose: APR-246 (PRIMA-1MET) is a novel drug that restores transcriptional activity of unfolded wild-type or mutant p53. The main aims of this first-in-human trial were to determine maximum-tolerated dose (MTD), safety, dose-limiting toxicities (DLTs), and pharmacokinetics (PK) of APR-246.

Patients And Methods: APR-246 was administered as a 2-hour intravenous infusion once per day for 4 consecutive days in 22 patients with hematologic malignancies and prostate cancer.

Prognostic DNA methylation patterns in cytogenetically normal acute myeloid leukemia are predefined by stem cell chromatin marks.

Cytogenetically normal acute myeloid leukemia (CN-AML) compose between 40% and 50% of all adult acute myeloid leukemia (AML) cases. In this clinically diverse group, molecular aberrations, such as FLT3-ITD, NPM1, and CEBPA mutations, recently have added to the prognostic accuracy. Aberrant DNA methylation is a hallmark of cancer, including AML.

Inverse relationship between leukaemic cell burden and plasma concentrations of daunorubicin in patients with acute myeloid leukaemia.

Aims: It has been shown that the cellular uptake and cytotoxicity of anthracyclines decrease with increasing cell density in vitro, an event termed 'the inocculum effect'. It is not known whether such an effect occurs in vivo. In this study the relationships between white blood cell (WBC) count, plasma and cellular concentrations of daunorubicin (DNR) in patients with acute myeloid leukaemia were investigated.

APR-246 exhibits anti-leukemic activity and synergism with conventional chemotherapeutic drugs in acute myeloid leukemia cells.

Background: APR-246 belongs to a new generation of the compounds that restore normal p53 function in cells with mutated or wild type p53. The purpose of this study was to examine the effects of APR-246 alone and in combination with other drugs in acute myeloid leukemia (AML) cells.

Methods: Primary leukemic cells from patients with AML and AML cell lines were studied with respect to cytotoxic and apoptotic effects and mechanism of action of APR-246, alone and in combination with Ara-C, daunorubicin and fludarabine.

Daunorubicin metabolism in leukemic cells isolated from patients with acute myeloid leukemia.

Background: Anthracyclines like daunorubicin (DNR) are important drugs in the treatment of acute myeloid leukaemia (AML). In vitro studies have shown that cellular metabolism of anthracyclines could play a role in drug resistance. Currently, it is not known what enzyme is responsible for anthracycline metabolism in leukemic cells.

Topoisomerase IIalpha expression in acute myeloid leukaemia cells that survive after exposure to daunorubicin or ara-C.

Patients diagnosed with acute myeloid leukaemia are often treated with a combination of daunorubicin and 1-beta-D-arabinofuranosylcytosine (ara-C). Both daunorubicin and ara-C exert their effects in the cell nucleus but by different mechanisms, i.e.

Uptake of anthracyclines in vitro and in vivo in acute myeloid leukemia cells in relation to apoptosis and clinical response.

Aims: To study anthracycline-induced apoptosis in leukemic cells isolated from patients with acute myelogenous leukemia (AML) in vitro and to compare intracellular anthracycline concentrations causing apoptosis in vitro with those obtained in vivo during anthracycline treatment.

Methods: Mononuclear blood cells from AML patients were isolated before (n = 20) and after anthracycline infusion (n = 24). The pre-treated cells were incubated in vitro with daunorubicin (DNR) and/or idarubicin (IDA).

Selenite is a potent cytotoxic agent for human primary AML cells.

Selenite is a potent inhibitor of malignant cell growth. Although the cytotoxic effects have been extensively investigated in vitro, there are only a limited number of studies using primary tumor cells with concomitant comparison to conventional drugs. An ex vivo model with primary cells from 39 consecutive patients with acute myeloid leukemia (AML) were exposed to a panel of conventional cytotoxic drugs, and the effects on viability were compared to those of clinically achievable concentrations of selenite.

Chromosomal aberrations in 17p predict in vitro drug resistance and short overall survival in acute myeloid leukemia.

Chromosomal aberrations are important prognostic parameters in acute myeloid leukemia (AML). Indicators of poor prognosis include del(5q)/-5, del(7q)/-7, abnormal 3q or complex karyotype. In recent years, it has become clear that aberrations in 17p represent one of the indicators of poor prognosis in haematological malignancies.

The FLT3 inhibitor PKC412 in combination with cytostatic drugs in vitro in acute myeloid leukemia.

An internal tandem duplication of FLT3 (FLT3/ITD) occurs in approximately 25% of newly diagnosed AML. PKC412 inhibits the growth of leukemic cell lines with FLT3 mutations such as the MV4-11. This study evaluated the in vitro effects of the combination of PKC412 and ara-C or daunorubicin, studying the effect of co-incubation, pre-incubation and sequential incubation of the drugs in patient samples and cell lines.

Higher plasma but not intracellular concentrations after infusion with liposomal daunorubicin compared with conventional daunorubicin in adult acute myeloid leukemia.

To investigate the plasma and intracellular pharmacokinetics of liposomal daunorubicin (DaunoXome) in comparison with conventional daunorubicin, 14 patients aged 28 to 60 years with newly diagnosed acute myeloid leukemia were treated for 1 day with DaunoXome (50 mg/m) and for 2 days with daunorubicin (50 mg/m) with concomitant Ara-C (7 days, 200 mg/m, continuous IV). Eleven of the 14 patients entered complete remission; 9 are still alive. Pharmacokinetic profiles were obtained by blood sampling at appropriate intervals on days 1 to 4.

Topoisomerase IIalpha mRNA and protein expression vs. in vitro drug resistance and clinical outcome in acute leukaemia.

The objective of this study was to correlate the expression of topoisomerase (topo) IIalpha to in vitro drug sensitivity and to the clinical outcome in patients with acute leukaemia. Leukaemic cells were isolated from bone marrow or blood from 94 patients. Topo IIalpha mRNA (n=58) and protein (n=60) expression was determined by real-time RT-PCR and flow cytometry, respectively.

Successful mobilization of Ph-negative blood stem cells with intensive chemotherapy + G-CSF in patients with chronic myelogenous leukemia in first chronic phase.

The aim of the study was to investigate the feasibility of mobilizing Philadelphia chromosome negative (Ph-) blood stem cells (BSC) with intensive chemotherapy and lenograstim (G-CSF) in patients with CML in first chronic phase (CP1). During 1994-1999 12 centers included 37 patients <56 years. All patients received 6 months' IFN, stopping at median 36 (1-290) days prior to the mobilization chemotherapy.

Intensive treatment and stem cell transplantation in chronic myelogenous leukemia: long-term follow-up.

In the present study we combined interferon (IFN) and hydroxyurea (HU) treatment, intensive chemotherapy and autologous stem cell transplantation (SCT) in newly diagnosed chronic myelogenous leukemia patients aged below 56 years, not eligible for allogeneic SCT. Patients who had an HLA-identical sibling donor and no contraindication went for an allogeneic SCT (related donor, RD). After diagnosis, patients not allotransplanted received HU and IFN to keep WBC and platelet counts low.

BCRP mRNA expression v. clinical outcome in 40 adult AML patients.

Efflux pumps are considered being mechanisms behind drug resistance in acute myeloid leukaemia (AML). A recently described efflux pump, breast cancer resistance protein (BCRP), can be expressed in AML, but its clinical importance is uncertain. In this study BCRP mRNA expression was determined in samples from 40 AML patients by real-time RT-PCR.

Comparison of busulphan, hydroxyurea and allogeneic bone marrow transplantation (BMT) in chronic myeloid leukaemia: BMT prolongs survival.

Introduction: Whether busulphan-treated patients develop blastic transformation earlier than hydroxyurea treated has been a controversial issue. In a randomised prospective study, we examined the busulphan versus hydroxyurea influence on time to blast crisis and on survival. When we opened our study in 1984, the clinical benefit of allogeneic bone marrow transplantation (BMT) was not well known; to follow up the long-time outcome of this treatment was therefore of great interest.

Mammalian thioredoxin reductase alters cytolytic activity of an antibacterial peptide.

Granulysin is a disulfide rich 9 kDa human tumoricidal protein produced by cytolytic cells. Here we show that thioredoxin reductase (TrxR) reduced a 23-residue peptide from granulysin (GranF2), and this markedly enhanced the killing of small cell lung cancer cells (SCLC) by GranF2. Cells treated with reduced GranF2 showed rapid ATP deletion within 90 min and strong annexin V staining after 4 h incubation.

Mechanisms of cross-resistance between nucleoside analogues and vincristine or daunorubicin in leukemic cells.

The aim of this study was to clarify the biochemical and molecular mechanisms behind the cross-resistance to nucleoside analogues (NAs) in four erythroleukemic cell lines with acquired resistance to the anthracycline daunorubicin and to the vinca alkaloid vincristine, expressing high levels of p-glycoprotein (P-gp, MDR1). All resistant strains exhibited cross-resistance to NA (cladribine and cytosine arabinoside)-induced apoptosis, assessed by caspase-3-like activation and were less sensitive to NA cytotoxicity in MTT assay. Real-time PCR and enzyme activity analysis showed reduced amounts of deoxycytidine kinase (35-80%) and elevated levels of 5'-nucleotidases (50-100%).

Selenite-induced apoptosis in doxorubicin-resistant cells and effects on the thioredoxin system.

Selenium treatment of the doxorubicin-resistant cell line, U-1285dox, derived from human small cell carcinoma of the lung, resulted in massive apoptosis. This effect appeared maximal at 2 days after addition of selenite. The apoptosis was caspase-3 independent as revealed by Western blot analysis, activity measurement and by using caspase inhibitors.

Increased remissions from one course for intermediate-dose cytosine arabinoside and idarubicin in elderly acute myeloid leukaemia when combined with cladribine. A randomized population-based phase II study.

Cladribine has single-drug activity in acute myeloid leukaemia (AML), and may enhance the formation of the active metabolite (ara-CTP) of cytosine arabinoside (ara-C). To evaluate the feasibility of adding intermittent cladribine to intermediate-dose ara-C (1 g/m2/2 h) b.i.

In vitro chemosensitivity testing of selected myeloid cells in acute myeloid leukemia.

In several studies different chemosensitivity assays have been examined in acute myeloid leukemia (AML). Some have shown that in vitro chemosensitivity testing is an independent prognostic factor but so far no one has been able to show that the use of these methods can improve treatment outcome. In an attempt to improve in vitro chemosensitivity testing in AML we wanted to establish and evaluate a new flow cytometry chemosensitivity assay.

Doxorubicin-resistant, MRP1-expressing U-1285 cells are sensitive to idarubicin.

A doxorubicin-resistant subline (U-1285dox(900)) was derived from the human small cell lung carcinoma cell line U-1285. U-1285dox(900) was exposed to a wide range of anticancer agents to determine its resistance profile. In contrast to U-1285 cells, the resistant subline U-1285dox(900) expressed elevated MRP1 mRNA detected by reversed transcriptase-polymerase chain reaction (RT-PCR) and MRP1 protein analyzed with Western blot.

A phase I/II study of the MDR modulator Valspodar (PSC 833) combined with daunorubicin and cytarabine in patients with relapsed and primary refractory acute myeloid leukemia.

The cyclosporine analog Valspodar (PSC 833, Novartis Pharma) is a strong inhibitor of the mdr1 gene product p-glycoprotein (pgp). A phase I/II study was conducted in order to evaluate if addition of Valspodar to treatment with daunorubicin and cytarabine, given to patients with primary refractory or relapsed acute myeloid leukemia, could increase the complete remission rate.Fifty-three patients were treated in cohorts of three to six patients.