Effects of methylprednisolone on human myeloid leukemic cells in vitro

Dexamethasone enhances venetoclax-induced apoptosis in acute myeloid leukemia cells

Acute myeloid leukemia (AML) therapies have been significantly improved by the development of medicines that can target BCL-2. On the other hand, non-recurrent alterations in oncogenic pathways and gene expression patterns have already been linked to therapeutic resistance to venetoclax therapy. Bone marrow mesenchymal stromal cells (BM-MSCs) support leukemic cells in preventing chemotherapy-induced apoptosis by mitochondrial transfer in leukemic microenvironment. In this study, we investigated the enhancement of the antitumor effect of BCL-2 inhibitor venetoclax by dexamethasone. In particular, dexamethasone had no significant effect on the viability of AML cells, but dexamethasone combined with venetoclax could significantly increase the apoptosis of AML cells induced by venetoclax. When AML cells were co-cultured with BM-MSCs, dexamethasone combined with venetoclax showed additional anti-tumor effect compared to venetoclax alone. Venetoclax increased reactive oxygen species level in co-cultured AML cells, contributed to transfer more mitochondria from BM-MSCs to AML cells and protect AML cells from apoptosis. Dexamethasone combined with venetoclax induced more apoptosis, but dexamethasone reduced the venetoclax-induced reactive oxygen species level in AML cells and reduced the transfer of mitochondria from BM-MSCs to AML cells. This may lead to a diminished protective effect of BM-MSCs on AML cells. Together, our findings indicated that venetoclax in combination with dexamethasone could be a promising therapy in AML.

Protective effects of cytokine combinations against the apoptotic activity of glucocorticoids on CD34+ hematopoietic stem/progenitor cells

Haematopoietic stem cells can self-renew and produce progenitor cells, which have a high proliferation capacity. Chemotherapeutic drugs are toxic to normal cells as well as cancer cells, and glucocorticoids (GCs), which are essential drugs for many chemotherapeutic protocols, efficiently induce apoptosis not only in malignant cells but also in normal haematopoietic cells. Studies have shown that haematopoietic cytokines can prevent the apoptosis induced by chemotherapy and decrease the toxic effects of these drugs. However, the apoptosis induction mechanism of GCs in CD34⁺ haematopoietic cells and the anti-apoptotic effects of cytokines have not been well elucidated. In this study, we investigated the apoptotic effects of GCs on CD34⁺, a haematopoietic stem/progenitor cell (HSPC) population, and demonstrated the protective effects of haematopoietic cytokines. We used a cytokine cocktail containing early-acting cytokines, namely, interleukin-3 (IL-3), thrombopoietin, stem cell factor and flt3/flk2 ligand, and dexamethasone and prednisolone were used as GCs. Apoptotic mechanisms were assessed by immunohistochemical staining and quantified using H-scoring. Dexamethasone and prednisolone induced apoptosis in CD34⁺ HSPCs. GC treatment caused a significant increase in apoptotic Fas, caspase-3, cytochrome c and Bax, but a significant decrease in anti-apoptotic Bcl-2. Furthermore, as expected, cytokines caused a significant decrease in all apoptotic markers and a significant increase in Bcl-2. Thus, our findings suggest that CD34⁺ HSPCs are an extremely sensitive target for GCs and that cytokines protect these cells from GC-induced apoptosis.

Leukemic stem cell signatures identify novel therapeutics targeting acute myeloid leukemia

Therapy for acute myeloid leukemia (AML) involves intense cytotoxic treatment and yet approximately 70% of AML are refractory to initial therapy or eventually relapse. This is at least partially driven by the chemo-resistant nature of the leukemic stem cells (LSCs) that sustain the disease, and therefore novel anti-LSC therapies could decrease relapses and improve survival. We performed in silico analysis of highly prognostic human AML LSC gene expression signatures using existing datasets of drug–gene interactions to identify compounds predicted to target LSC gene programs. Filtering against compounds that would inhibit a hematopoietic stem cell (HSC) gene signature resulted in a list of 151 anti-LSC candidates. Using a novel in vitro LSC assay, we screened 84 candidate compounds at multiple doses and confirmed 14 drugs that effectively eliminate human AML LSCs. Three drug families presenting with multiple hits, namely antihistamines (astemizole and terfenadine), cardiac glycosides (strophanthidin, digoxin and ouabain) and glucocorticoids (budesonide, halcinonide and mometasone), were validated for their activity against human primary AML samples. Our study demonstrates the efficacy of combining computational analysis of stem cell gene expression signatures with in vitro screening to identify novel compounds that target the therapy-resistant LSC at the root of relapse in AML.

Enhanced sensitivity to glucocorticoids in cytarabine-resistant AML

We sought to identify drugs that could counteract cytarabine resistance in acute myeloid leukemia (AML) by generating eight resistant variants from MOLM-13 and SHI-1 AML cell lines by long-term drug treatment. These cells were compared with 66 ex vivo chemorefractory samples from cytarabine-treated AML patients. The models and patient cells were subjected to genomic and transcriptomic profiling and high-throughput testing with 250 emerging and clinical oncology compounds. Genomic profiling uncovered deletion of the deoxycytidine kinase (DCK) gene in both MOLM-13- and SHI-1-derived cytarabine-resistant variants and in an AML patient sample. Cytarabine-resistant SHI-1 variants and a subset of chemorefractory AML patient samples showed increased sensitivity to glucocorticoids that are often used in treatment of lymphoid leukemia but not AML. Paired samples taken from AML patients before treatment and at relapse also showed acquisition of glucocorticoid sensitivity. Enhanced glucocorticoid sensitivity was only seen in AML patient samples that were negative for the FLT3 mutation (P=0.0006). Our study shows that development of cytarabine resistance is associated with increased sensitivity to glucocorticoids in a subset of AML, suggesting a new therapeutic strategy that should be explored in a clinical trial of chemorefractory AML patients carrying wild-type FLT3.

Comparison of megadose methylprednisolone versus conventional dose prednisolone in hematologic disorders

Glucocorticoids (GCs) are known for their clinically useful effects in immunologic and inflammatory disorders. Although there is a huge volume of knowledge concerning the cellular and molecular effects of GCs, statements regarding their effects in multiple diseases at variable doses are not clear-cut owing to pharmacogenetic differences. The main actions of GCs in hematologic disorders have been related to their differentiation-inducing and apoptosis-inducing effects, but modification of several steps of the hematopoietic and/or immune pathway has also been reported. In our clinic, mega-dose methylprednisolone (MDMP) has been successfully used for treatment of different hematologic diseases, such as leukemias, bone marrow failure in aplastic anemia, hypoplastic anemia, myelodysplastic syndrome, neutropenia, autoimmune diseases, and in some congenital hereditary diseases. Both clinical and experimental studies in our department revealed that MDMP was more effective than conventional dose steroids. It is interesting that MDMP can be curative in some congenital hereditary diseases such as Diamond-Blackfan syndrome. However, more research is required to clarify their roles in biology, physiology, and molecular genetics.

The effect of steroid on myeloid leukemic cells: The potential of short-course high-dose methylprednisolone treatment in inducing differentiation, apoptosis and in stimulating myelopoiesis

Several in vitro studies have shown that dexamethasone (Dex) and prednisolone can induce differentiation of some mouse and human myeloid leukemic cells to macrophages and granulocytes. Based on in vitro experiments, we have shown that short-course (3-7 days) high-dose methylprednisolone (HDMP) (20-30 mg/kg/day) treatment can induce differentiation of myeloid leukemic cells in vivo in children with different subtypes of acute myeloblastic leukemia (AML) (AML-M1, -M2, -M3, -M4, -M7). We have also shown that induction of apoptosis of myeloid leukemic cells with or without differentiation is possible by short-course HDMP treatment. In addition, short-course HDMP treatment has been shown to be effective in accelerating leukocyte recovery, possibly stimulating normal CD34-positive hematopoietic progenitor cells. Addition of HDMP to mild cytotoxic chemotherapy (low-dose cytosine arabinoside (LD-Ara-c), weekly mitoxantrone and Ara-c or 6-thioguanine) increased the remission rate (87-89%) and improved the outcome of AML children. We believe that the results of our 17-year clinical experience will provide important benefits to AML patients.

Children with acute myeloblastic leukemia presenting with extramedullary infiltration: the effects of high-dose steroid treatment

To evaluate whether children with acute myeloblastic leukemia (AML) presenting with extramedullary infiltration (EMI) have different clinical, morphologic features and prognosis from children without EMI, a 127 consecutive previously untreated children with AML were entered in this study. Fifty-one children (40%) had EMI at diagnosis and 27% of these showed multiple site involvement. Twenty-seven of 127 children (21%) presented myeloid tumors. No age related differences in the incidence of EMI was noted. However, analysis of clinical and biological features at diagnosis showed that WBC count > or =50 x 10(9) l(-1), hepatosplenomegaly >5 cm, FAB AML-M4 and AML-M5 subtypes and CD13, CD14 expression of bone marrow (BM) leukemic cells (>20%) were more frequent in children with EMI. Two consecutive treatment protocols were used. In both protocols remission was achieved with combined high-dose methylprednisolone (HDMP) as a differentiating and apoptosis inducing agent with mild cytotoxic chemotherapy (low-dose cytosine arabinoside (LD Ara-C), weekly mitoxantrone and Ara-C or 6-thioguanine). Administration of short-course (4-7 days) HDMP (20-30 mg/kg per day) alone resulted in a remarkable decrease in peripheral blood, BM blasts and in the size of EMI in responding patients. In both protocols, remission rate in patients with EMI was 71 and 80%, which was lower than that of the patients without EMI (87 and 89%). This may be attributed to the higher frequency of unfavorable features in children with EMI. However, in patients who presented with myeloblastoma and treated with a more intensive post-remission therapy (AML-94), the 4-year disease-free survival (DFS) and event-free survival (EFS) rates were not found to be significantly different from children who had no EMI (P>0.05). Whereas, the outcome of children who presented with gingival infiltration did not improve. In further studies, the prognostic significance of different localisation of EMI and the effect of addition of HDMP to cytotoxic chemotherapy should be explored in larger series.

The potential effect of short-course high-dose steroid on the maturation and apoptosis of leukemic cells in a child with acute megakaryoblastic leukemia

High-dose methylprednisolone (HDMP) treatment has been shown to induce differentiation of myeloid leukemic cells in children with acute promyelocytic leukemia and other subtypes (FAB AML M1-M2-M4) of acute myeloblastic leukemia. In the present study, a child with acute megakaryoblastic leukemia (AMKL) was given HDMP (30 mg/kg/day) orally in a single dose for the first 4 days of induction therapy. A marked decrease in peripheral blood blast cells and an increase in platelet count associated with a striking change in bone marrow (BM) morphology was observed following a short-course of HDMP treatment alone. BM cells developed distinct morphology characterized by cytoplasmic blebbing and some appeared as platelet producing micromegakaryocytes. Flow cytometric analysis of the BM cells 4 days after HDMP treatment demonstrated a decrease in the percentage of cells co-expressing CD34 and CD117 antigens and a marked increase in CD42a antigen. These changes in BM morphology and immunophenotype may suggest maturation effect of HDMP on megakaryocytic leukemic cells. In addition ultrastructural analysis of BM cells cultured with methylprednisolone (10(-3) and 10(-6) M) for 24 and 48 h showed numerous apoptotic cells. This was coincident with a significant increase in the percentage of annexin positive cells. These results suggest that HDMP treatment may induce differentiation and apoptosis of leukemic cells in a child with AMKL and it could be a promising agent for remission induction of patients with AMKL.

The effect of short-course high-dose methylprednisolone on peripheral blood lymphocyte subsets in children with acute leukemia during remission induction treatment

We have previously demonstrated a favorable effect of high-dose steroid in the treatment of children with acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML). This study was performed to determine the effect of short-course high-dose methylprednisolone (HDMP) treatment on the peripheral blood (PB) T lymphocyte subsets, and blast cells, during remission induction treatment in 23 children with newly diagnosed acute leukemia (16 with ALL, seven with AML). All patients were administered HDMP as a single daily oral dose of 30mg/kg for the first 4 days of induction therapy. The number of PB lymphocyte subsets (CD3, CD4, CD8, CD16+56, CD45RA, and CD45RO) were determined by flow cytometry before and after 4 days of HDMP treatment. While the number of PB blast cells significantly decreased, the absolute number of T lymphocytes expressing CD3, CD4, CD8, CD45RA and the absolute number of CD16+56 (natural killer) cells increased in all patients. We suggest that the beneficial effects of HDMP in the induction treatment of acute leukemia may occur partly due to an increase in the number of PB T lymphocyte subsets. A study randomly assigning patients to treatment with either conventional therapy or HDMP may provide further information.

Evaluation of children with myelodysplastic syndrome: importance of extramedullary disease as a presenting symptom

Thirty-three children diagnosed with primary myelodysplastic syndrome (MDS) in a single institution over an 8 year period were evaluated with special emphasis on children who presented with extramedullary disease (EMD). EMD was present at diagnosis in 12 (36%) of the 33 children with MDS. Three patients with juvenile myelomonocytic leukemia (JMML) and 2 patients with chronic myelomonocytic leukemia (CMML) presented with pleural effusion. Pericardial effusion was present in 3 of these patients, two of whom also had thrombosis. Pyoderma gangrenosum, relapsing polychondritis were the initial findings in another two cases with JMML. Lymphadenopathy (n=1), gingival hypertrophy (n=2), orbital granulocytic sarcoma (n=1) and spinal mass (n=1) were the presenting findings in 5 patients with refractory anemia with excess of blasts in transformation. Since high-dose methylprednisolone (HDMP, 20-30 mg/kg/day) has been shown to induce differentiation and apoptosis of myeloid leukemic cells in children with different morphological subtypes of acute myeloid leukemia in vivo and in vitro, 25 children with de novo MDS were treated with combined HDMP and cytotoxic chemotherapy. Dramatic improvement of EMD and decrease in blast cells both in the peripheral blood and bone marrow were obtained following administration of short-course HDMP treatment alone as observed in children with AML. HDMP, combined with low-dose cytosine arabinoside and mitoxantrone were used for the remission induction. Remission was achieved in 8 (80%) of 10 children who presented with EMD and in 9 (60%) of 15 children without EMD. Long-term remission (>6 years) was obtained in 4 (two with JMML and two with CMML), three of whom presented with EMD. In conclusion EMD can be a presenting finding in childhood MDS as observed in adults. In addition, the beneficial effect of HDMP combined with more intensive chemotherapy should be explored as alternative therapy in children with MDS not suitable for bone marrow transplantation.

Cytodifferentiation: a novel approach to cancer treatment and prevention

Cytodifferentiation therapy promises to control cancer growth and progression with less serious side effects than cytotoxic chemotherapy. Despite recent progress, the molecular mechanisms regulating the differentiation of many cell types are still obscure and the number of active cytodifferentiating agents is limited. Rational ways to develop these types of agents are necessary.

Remission of acute myeloblastic leukemia after severe pneumonia treated with high-dose methylprednisolone

We report a case of acute myeloblastic leukemia (AML)-M2 (by French-American-British classification) with t(8;21) (q22:q22) that was complicated with severe pneumonia. The patient tested positive by fluorescence in situ hybridization (FISH) for AML1 splitting and positive by reverse transcriptase polymerase chain reaction (RT-PCR) for chimeric AML1/MTG8 messenger RNA (mRNA), which indicated splitting of the MTG8 gene on chromosome 8 (q22) and the AMLI gene on chromosome 22 (q22). High-dose methylprednisolone was administered, and the leukemic cells disappeared without chemotherapy, although dysplastic hematopoietic cells were observed transiently after the first therapy. After the disappearance of leukemic cells, FISH for AML1 splitting was negative, and real-time PCR results for quantitative chimeric AML1/ MTG8 mRNA were less than the detectable level, however, RT-PCR results for AML1/MTG8 mRNA remained positive. These findings suggest that the patient acquired morphological, cytogenetic. and possibly molecular genetic remission by the synergistic effects of severe infection and high-dose methylprednisolone.

Induction of differentiation and apoptosis- a possible strategy in the treatment of adult acute myelogenous leukemia

A differentiation block with accumulation of immature myeloid cells characterizes acute myelogenous leukemia (AML). However, native AML cells often show some morphological signs of differentiation that allow a classification into different subsets, and further differentiation may be induced by exposure to various soluble mediators, e.g., all trans-retinoic acid (ATRA) and several cytokines. Combination therapy with ATRA and chemotherapy should now be regarded as the standard treatment for the acute promyelocytic leukemia variant of AML. Several agents can induce leukemic cell differentiation for other AML subtypes, although these effects differ between patients. Differentiation may then be associated with induction of apoptosis, and differentiation-inducing therapy may therefore become useful in combination with intensive chemotherapy to increase the susceptibility of AML blasts to drug-induced apoptosis. However, it should be emphasized that differentiation and apoptosis can occur as separate events with different regulation in AML cells, and future studies in AML should therefore focus on: A) the identification of new agents with more predictable effects on differentiation and apoptosis; B) the use of clinical and laboratory parameters to define new subsets of AML patients in which differentiation/apoptosis induction has a predictable and beneficial effect, and C) further characterization of how AML blast sensitivity to drug-induced apoptosis is modulated by differentiation induction.

New strategies for the treatment of acute myelogenous leukemia: differentiation induction--present use and future possibilities

A differentiation block and an accumulation of immature myeloid cells characterize acute myelogenous leukemia (AML). However, native AML cells usually show some morphological signs of differentiation that allow a classification into different subsets, and further differentiation may be induced by exposure to various soluble mediators, for example, all-trans retinoic acid (ATRA) and several cytokines. Combination therapy with ATRA and chemotherapy should now be regarded as the standard treatment of the acute promyelocytic leukemia (APL) variant of AML. Although several agents can also induce leukemic cell differentiation for other AML subgroups, in vitro studies as well as clinical data have demonstrated that these agents often have heterogeneous effects on the leukemic progenitors. This makes the clinical impact of differentiation induction therapy for individual patients difficult to predict. However, differentiation induction should be regarded as a promising therapeutic approach, especially as a part of immunotherapy or in combination with intensive chemotherapy to increase the susceptibility of AML blasts to drug-induced apoptosis. Although the morphology-based French-American-British classification was used to identify APL as an AML subset that required a special treatment, it seems unlikely that this classification alone can be used to identify new subsets of AML patients with special therapeutic requirements. Future studies on differentiation induction in AML should therefore focus on A) the identification of therapeutic agents with more predictable effects; B) the use of clinical and laboratory parameters to define new subsets of AML patients in which differentiation induction has a predictable and beneficial effect, and C) the characterization of how AML blast sensitivity to drug-induced apoptosis is altered by differentiation induction.