Involvement of ERK/MAPK pathway in megakaryocytic differentiation of K562 cells induced by 3-hydrogenkwadaphnin

Nanocurcumin as a novel stimulator of megakaryopoiesis that ameliorates chemotherapy-induced thrombocytopenia in mice

AIMS

Platelet production improvement can resolve concerns about the limitations of external platelet supply and platelet transfusion in thrombocytopenia patients. To this end, scientists encourage to induce the generation of megakaryocyte and platelet. Curcumin is a safe ingredient of turmeric that affects various cellular pathways. The effect of this component on platelet production has not been yet reported.

MAIN METHODS

Our in vitro experiments include the investigation of the effects of nanocurcumin on megakaryocytes production from K562 cells and hematopoietic stem cells via megakaryocyte markers expression, DNA content, ROS, and morphologic analysis, and CFC assay. The regulatory functions of MAPKs pathways were also determined. In the in vivo study tissue distribution of nanocurcumin was determined and two treatment schedules were used to evaluate the capability of nanocurcumin to prevent the occurrence of Busulfan-induced thrombocytopenia in the mouse model.

KEY FINDING

In vitro evidences demonstrated that nanocurcumin can induce MK production from K562 cells and hematopoietic stem cells. Inhibition of ERK1/2 and JNK pathways arrested this activity. In vivo experiments showed the uptake of nanocurcumin by tissues in mice. Administration of nanocurcumin could preserve bone marrow integrity and increase of the number of circulating platelets in the Busulfan-treated mice models.

SIGNIFICANCE

Our results have demonstrated that nanocurcumin administration can be useful for the improvement of megakaryocytes and platelet generation in vitro. This component may be exerting these beneficial effects on megakaryopoiesis by modulating ERK1/2 and JNK pathways. As well as nanocurcumin has the potential to prevent thrombocytopenia in chemotherapy threated mice.

Sensitizing effect of juglone is mediated by down regulation of Notch1 signaling pathway in trastuzumab-resistant SKBR3 cells

Trastuzumab (Herceptin) monoclonal antibody directed against HER2 receptor has been administered as a treatment for metastatic HER2 positive breast cancer. The problematic issue in treatment of HER2 positive breast cancer cells is commonly the induction of resistance to trastuzumab which might be due to modulation of some vital signaling elements such as Notch1 and Pin1. In this study, we were aimed to investigate whether the cross talk between pin1 and Notch1 has a role in this event. Our results indicated that the expression level of Pin1 in resistant SKBR3 cells increased by about twofold relative to sensitive SKBR3 cells. Besides, Pin1 inhibition via juglone reduced the extent of proliferation, colony formation and migration capacity of resistant SKBR3 cells. In addition, despite a feed forward loop between Notch1 and Pin1 in sensitive SKBR3 cells, inhibition of Notch1 cleavage in resistant SKBR3 cells did not affect pin1 level whereas pin1 inhibition by juglone reduced the level of Hes1, p-Akt and increased the cellular content of Numb. Therefore, we concluded that pin1 inhibition could be considered as a promising sensitizing strategy to weaken trastuzumab resistance.

Lapatinib induces autophagic cell death and differentiation in acute myeloblastic leukemia

Lapatinib is an oral-form dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR or ErbB/Her) superfamily members with anticancer activity. In this study, we examined the effects and mechanism of action of lapatinib on several human leukemia cells lines, including acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and acute lymphoblastic leukemia (ALL) cells. We found that lapatinib inhibited the growth of human AML U937, HL-60, NB4, CML KU812, MEG-01, and ALL Jurkat T cells. Among these leukemia cell lines, lapatinib induced apoptosis in HL-60, NB4, and Jurkat cells, but induced nonapoptotic cell death in U937, K562, and MEG-01 cells. Moreover, lapatinib treatment caused autophagic cell death as shown by positive acridine orange staining, the massive formation of vacuoles as seen by electronic microscopy, and the upregulation of LC3-II, ATG5, and ATG7 in AML U937 cells. Furthermore, autophagy inhibitor 3-methyladenine and knockdown of ATG5, ATG7, and Beclin-1 using short hairpin RNA (shRNA) partially rescued lapatinib-induced cell death. In addition, the induction of phagocytosis and ROS production as well as the upregulation of surface markers CD14 and CD68 was detected in lapatinib-treated U937 cells, suggesting the induction of macrophagic differentiation in AML U937 cells by lapatinib. We also noted the synergistic effects of the use of lapatinib and cytotoxic drugs in U937 leukemia cells. These results indicate that lapatinib may have potential for development as a novel antileukemia agent.

MR-1 blocks the megakaryocytic differentiation and transition of CML from chronic phase to blast crisis through MEK dephosphorylation

Chronic myelogenous leukemia (CML) evolves from a chronic phase characterized by the Philadelphia chromosome as the sole genetic abnormality and the accumulation of mature cells in peripheral blood into blast crisis, which is characterized by the rapid expansion of myeloid- or lymphoid-differentiation-arrested blast cells. Although ample studies have been conducted on the disease progress mechanisms, the underlying molecular mechanisms of the malignant phenotype transition are still unclear. In this study, we have shown that myofibrillogenesis regulator-1 (MR-1) was overexpressed in blast crisis patients and leukemic cells, but there was little trace expressed in healthy individuals and in most patients in CML chronic phase. MR-1 could inhibit the differentiation of myeloid cells into megakaryocytic lineages and accelerate cell proliferation. The molecular mechanism responsible for these effects was the interaction of MR-1 with MEK, which blocked the MEK/ERK signaling pathway by dephosphorylating MEK. Our results provide compelling and important evidence that MR-1 might act as a diagnostic marker and potential target of CML progression from chronic phase to blast crisis.

Self-assembled metalla-rectangles bearing azodipyridyl ligands: synthesis, characterization and antitumor activity

Sixteen arene-Ru based molecular-rectangles were self-assembled in high yields by the equimolar mixing of arene-Ru acceptors (Aa-Ad) with various azopyridyl ligands (1,2-di(pyridyl-4yl)diazene (L1), 1,2-bis(pyridin-4-ylmethylene)hydrazine (L2), 1,2-bis(1-(pyridin-4-yl)ethylidene)hydrazine (L3), 1,2-bis(pyridin-4-ylmethylene)hydrazine (L4)) in nitromethane-methanol solutions. These new molecular-rectangles were fully characterized by a host of analytical techniques including elemental analysis, (1)H and (13)C NMR and HR-ESI-MS. The solid-state structures of two molecular-rectangles (1b and 4d) were determined by single crystal X-ray diffraction data. UV-visible and fluorescence studies were also carried out for the entire suite of rectangles. As with recent studies of similar arene-Ru complexes, the anti-proliferative activities of these complexes were evaluated against SK-hep-1 (liver cancer) and A-549 (lung cancer) human cancer lines. Additionally, the cellular pharmacology and intracellular localizations in AGS (gastric cancer) human cancer cells were determined for selected complexes (1c, 1d and 4c) by apoptosis and fluorescence microscopy studies. These studies confirm that arene-Ru molecular-rectangles inhibit cell cycle progression to the G0 phase, in contrast to that of cisplatin which arrests cell growth in the G2 phase.

Proteomic and systems biology analysis of monocytes exposed to securinine, a GABA(A) receptor antagonist and immune adjuvant

Securinine, a GABA(A) receptor antagonist, has been reported to enhance monocyte cell killing of Coxiella burnetii without obvious adverse effects in vivo. We employed multiplex 2D gel electrophoresis using Zdyes, a new generation of covalently linked fluorescent differential protein detection dyes to analyze changes in the monocyte proteome in response to Securinine. Securinine antagonism of GABA(A) receptors triggers the activation of p38. We used the differential protein expression results to guide a search of the literature and network analysis software to construct a systems biology model of the effect of Securinine on monocytes. The model suggests that various metabolic modulators (fatty acid binding protein 5, inosine 5'-monophosphate dehydrogenase, and thioredoxin) are at least partially reshaping the metabolic landscape within the monocytes. The actin bundling protein L-plastin, and the Ca(2+) binding protein S100A4 also appear to have important roles in the immune response stimulated by Securinine. Fatty acid binding protein 5 (FABP5) may be involved in effecting lipid raft composition, inflammation, and hormonal regulation of monocytes, and the model suggests that FABP5 may be a central regulator of metabolism in activated monocytes. The model also suggests that the heat shock proteins have a significant impact on the monocyte immune response. The model provides a framework to guide future investigations into the mechanisms of Securinine action and with elaboration may help guide development of new types of immune adjuvants.

Methanol extract of Antrodia cinnamomea mycelia induces phenotypic and functional differentiation of HL60 into monocyte-like cells via an ERK/CEBP-β signaling pathway

Antrodia cinnamomea (named as Niu-chang-chih), a well-known Taiwanese folk medicinal mushroom, has a spectrum of biological activities, especially with anti-tumor property. This study was carried out for the first time to examine the potential role and the underlying mechanisms of A. cinnamomea in the differentiation of human leukemia HL60 cells. We found that the methanol extract of liquid cultured mycelia of A. cinnamomea (MEMAC) inhibited proliferation and induced G1-phase cell cycle arrest in HL60 cells. MEMAC could induce differentiation of HL60 cells into the monocytic lineage, as evaluated by the morphological change, nitroblue tetrazolium reduction assay, non-specific esterase assay, and expression of CD14 and CD11b surface antigens. In addition, MEMAC activated the extracellular signal-regulated kinase (ERK) pathway and increased CCAAT/enhancer-binding protein β (C/EBPβ) expression. Reverse transcriptase polymerase chain reaction analysis showed that MEMAC upregulated the expression of C/EBPβ and CD14 mRNA in HL60 cells. DNA affinity precipitation assay and chromatin immunoprecipitation analyses indicated that MEMAC enhanced the direct binding of C/EBPβ to its response element located at upstream of the CD14 promoter. Furthermore, inhibiting ERK pathway activation with PD98059 markedly blocked MEMAC-induced HL60 monocytic differentiation. Consistently, the MEMAC-mediated upregulation of C/EBPβ and CD14 was also suppressed by PD98059. These findings demonstrate that MEMAC-induced HL60 cell monocytic differentiation is via the activating ERK signaling pathway, and downstream upregulating the transcription factor C/EBPβ and differentiation marker CD14 gene, suggesting that MEMAC might be a potential differentiation-inducing agent for treatment of leukemia.

Flow cytometric evaluation of cell cycle regulators (cyclins and cyclin-dependent kinase inhibitors) expressed on bone marrow cells in patients with chronic myeloid leukemia and multiple myeloma

Objective: The aim of this study was to use flow cytometry to analyze the expression of cell cycle-regulating elementswith low and high proliferative signatures in patients with malignant diseases.

Material and Methods: Cyclin D, E, A, and B, and cyclin-dependent kinase inhibitor (CDKI) p16 and p21 levels weremeasured via flow cytometry in patients with chronic myeloid leukemia (CML) (n = 16) and multiple myeloma (MM)(n = 13), and in controls (n = 15).

Results: The distributions of the cell cycle S phase were 10, 63%, 6, 72% and 3, 59%; for CML, MM and controlpatients, respectively. Among all the cyclins expressed during the S phase, cyclin D expression was the lowest in the CMLpatients. Distribution of cyclins and CDKIs during the G2/M phase was similar in the MM and control groups, whereascyclin expression was similar during all 3 phases in the MM and CML groups.

Conclusion: Elevated cyclin expression during cell cycle phases in the CML and MM patients was not associatedwith elevated CDKI expression. This finding may increase our understanding of the mechanisms involved in theetiopathogenesis of hematological malignancy.

Induction of differentiation by panaxydol in human hepatocarcinoma SMMC-7721 cells via cAMP and MAP kinase dependent mechanism

Panaxydol (PND) is one of the main non-peptidyl small molecules isolated from the lipophilic fractions of Panax notoginseng. The present study was carried out to demonstrate the potential effects of panaxydol on the induction of differentiation of human liver carcinoma cell lines SMMC-7721. Cell viability was evaluated by MTT method and Trypan blue exclusion assay respectively. The changes of morphology were detected by transmission electron microscope. Inhibitors were applied to detect the signaling pathway of differentiation. The level of intracellular cyclic AMP was determined by radioimmunoassay. The expression of p-ERK, Id1, and p21 were determined by Western blot. We found that panaxydol inhibit the proliferation of SMMC-7721 cells and caused the morphology and ultrastructure changes of SMMC-7721. Moreover, panaxydol dose-dependently increased the secretion of albumin and alkaline phosphatase activity, and decreased the secretion of AFP correspondingly. These changes of differentiation markers in SMMC-7721 can be reversed by the protein kinase A inhibitor RpcAMPS and by MAP kinase kinase 1/2 inhibitor U0126 or sorafenib. Intracellular cAMP was elevated by panaxydol in SMMC-7721 cells. Panaxydol dose-dependently decreased the expression of regulatory factors Id1 and increased the protein levels of p21 and p-ERK1/2 correspondingly. It suggested panaxydol might be of value for further exploration as a potential anti-cancer agent via cAMP and MAP kinase-dependent mechanism.

Chemosensitization of human leukemia K562 cells to taxol by a Vanadium-salen complex

Vanadium complexes are a heterogeneous class of compounds exhibiting interesting biological properties. Herein, we report the effect of a vanadium-salen complex (VO-salen) on proliferative behavior of K562 cell line. The results revealed that VO-salen at 6-32 μM inhibited K562 proliferation with no distinct alteration in cell morphology, extent of apoptosis and/or differentiation. Our results indicated that VO-salen complex has just a cytostatic effect and capable of arresting the affected cells in G2/M phase of cell cycle. In addition, we evaluated the combined effects of VO-salen complex and taxol. The cell cycle analyses showed that VO-salen complex enhanced taxol-induced G2/M arrest and also increased taxol-induced apoptosis through a decrease in the ratio of Bcl-2/Bax which might account for the decrease in the apoptosis threshold among the affected cells. These findings support that combination of VO-salen, as a chemosensitizer, and taxol might constitute an affective new strategy for leukemia therapy.

Induction of erythroid differentiation in human erythroleukemia cells by depletion of malic enzyme 2

Malic enzyme 2 (ME2) is a mitochondrial enzyme that catalyzes the conversion of malate to pyruvate and CO2 and uses NAD as a cofactor. Higher expression of this enzyme correlates with the degree of cell de-differentiation. We found that ME2 is expressed in K562 erythroleukemia cells, in which a number of agents have been found to induce differentiation either along the erythroid or the myeloid lineage. We found that knockdown of ME2 led to diminished proliferation of tumor cells and increased apoptosis in vitro. These findings were accompanied by differentiation of K562 cells along the erythroid lineage, as confirmed by staining for glycophorin A and hemoglobin production. ME2 knockdown also totally abolished growth of K562 cells in nude mice. Increased ROS levels, likely reflecting increased mitochondrial production, and a decreased NADPH/NADP+ ratio were noted but use of a free radical scavenger to decrease inhibition of ROS levels did not reverse the differentiation or apoptotic phenotype, suggesting that ROS production is not causally involved in the resultant phenotype. As might be expected, depletion of ME2 induced an increase in the NAD+/NADH ratio and ATP levels fell significantly. Inhibition of the malate-aspartate shuttle was insufficient to induce K562 differentiation. We also examined several intracellular signaling pathways and expression of transcription factors and intermediate filament proteins whose expression is known to be modulated during erythroid differentiation in K562 cells. We found that silencing of ME2 leads to phospho-ERK1/2 inhibition, phospho-AKT activation, increased GATA-1 expression and diminished vimentin expression. Metabolomic analysis, conducted to gain insight into intermediary metabolic pathways that ME2 knockdown might affect, showed that ME2 depletion resulted in high orotate levels, suggesting potential impairment of pyrimidine metabolism. Collectively our data point to ME2 as a potentially novel metabolic target for leukemia therapy.

Design, synthesis, and biological evaluation of a new palladium(II) complex: beta-lactoglobulin and K562 as targets

A water-soluble Pd(II) complex (2,2'-bipyridinglycinato Pd(II) nitrate) has been synthesized and characterized. The effect of synthesized complex on the carrier model protein structure and cell proliferation was investigated. Whey carrier protein beta-lactoglobulin-B (BLG-B) and chronic myelogenous leukemia cell line K562 were the targets. Fluorescence and CD instruments were used to assess effect of the complex on the protein structure at different temperatures. Growth inhibitory and apoptotic effect of the Pd(II) complex toward the cancer cells was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry. This complex exhibited potent cytotoxic properties against chronic myelogenous leukemia cell line K562. The cells showed different sensitivity to complex. Cytotoxic studies shown that Pd(II) complex induced apoptosis of K562 cells in a concentration and time dependent manner. Then, it might be concluded that Pd(II) complex is a promising antiproliferative agent and should execute its biological effects by inducing apoptosis. Results of fluorescence studies revealed that Pd(II) complex can quench the intrinsic fluorescence emission of the protein at different temperatures. The far- and near-UV CD studies displayed that the Pd(II) complex induces changes in the secondary and tertiary structures of BLG-B at different temperatures. The biological significance of this work is evident since BLG serves as a carrier molecule for several antitumor compounds. Therefore, the interaction of the Pd(II) complex (with antitumor activity) can provide useful information to better design metal anticancer complexes with fewer side effects.

Protein-arginine methyltransferase 1 suppresses megakaryocytic differentiation via modulation of the p38 MAPK pathway in K562 cells

Protein-arginine methyltransferase 1 (PRMT1) plays pivotal roles in various cellular processes. However, its role in megakaryocytic differentiation has yet to be investigated. Human leukemia K562 cells have been used as a model to study hematopoietic differentiation. In this study, we report that ectopic expression of HA-PRMT1 in K562 cells suppressed phorbol 12-myristate 13-acetate (PMA)-induced megakaryocytic differentiation as demonstrated by changes in cytological characteristics, adhesive properties, and CD41 expression, whereas knockdown of PRMT1 by small interference RNA promoted differentiation. Impairment of the methyltransferase activity of PRMT1 diminished the suppressive effect. These results provide evidence for a novel role of PRMT1 in negative regulation of megakaryocytic differentiation. Activation of ERK MAPK has been shown to be essential for megakaryocytic differentiation, although the role of p38 MAPK is still poorly understood. We show that knockdown of p38alpha MAPK or treatment with the p38 inhibitor SB203580 significantly enhanced PMA-induced megakaryocytic differentiation. Further investigation revealed that PRMT1 promotes activation of p38 MAPK without inhibiting activation of ERK MAPK. In p38alpha knockdown cells, PRMT1 could no longer suppress differentiation. In contrast, enforced expression of p38alpha MAPK suppressed PMA-induced megakaryocytic differentiation of parental K562 as well as PRMT1-knockdown cells. We propose modulation of the p38 MAPK pathway by PRMT1 as a novel mechanism regulating megakaryocytic differentiation. This study thus provides a new perspective on the promotion of megakaryopoiesis.