Distinct Gene Expression Pattern of CD34+ Stem and Progenitor Cells Mobilized by Pegfilgrastim after Cytotoxic Therapy in Multiple Myeloma in Comparison to G-CSF.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 5191-5191
Author(s):  
Ingmar Bruns ◽  
Ulrich Steidl ◽  
Guido Kobbe ◽  
Roland Fenk ◽  
Slawomir Kliszewski ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Cell Cycle Arrest ◽  
Progenitor Cells ◽  
Differentially Expressed ◽  
Cytotoxic Therapy ◽  
Cycle Arrest ◽  
Cd34 Cells ◽  
Genes Encoding ◽  
Stem And Progenitor Cells

Abstract Background: Current regimens for peripheral blood stem cell (PBSC) mobilization in patients with multiple myeloma are based on daily subcutaneous injections of G-CSF starting shortly after cytotoxic therapy. Recently a polyethylenglycole (PEG)-conjugated G-CSF (pegfilgrastim) has been introduced which has a substantially longer half-life than the original formula. Here, we compared the molecular phenotypes of CD34+ stem and progenitor cells mobilized by G-CSF with those mobilized by pegfilgrastim. Study design and Methods: We examined immunomagnetically enriched CD34+ cells from leukapheresis products of 8 patients who received G-CSF and of 8 patients who were given pegfilgrastim using Affymetrix HG Focus GeneChips covering 8793 genes. The statistical scripting language ‘R’ was used for data analysis. Significantly differentially expressed genes were identified with the Significance Analysis of Microarrays (SAM) algorithm. Results: Comparing CD34+ cells mobilized by G-CSF with pegfilgrastim-mobilized CD34+ cells 108 genes were differentially expressed (fold change 1.25 – 14.0, q- value 2.45–14.44%). 38 genes had a higher and 70 genes had a lower expression in CD34+ cells mobilized by G-CSF. We found upregulation of genes characteristic for erythropoietic differentiation including haemoglobin chains and Erythroid Kruppel-like factor in G-CSF-mobilized CD34+ cells. Utilizing clonogenic assays we were able to functionally corroborate this finding as G-CSF-mobilized cells gave rise to a significantly higher number of burst-forming units erythroid (BFU-E) as compared to colony forming units granulocyte-macrophage (CFU-GM) (p=0.016). Cell cycle regulating genes were differentially expressed as well. Genes encoding for proteins that cause cell cycle arrest including human HTm4 were upregulated in G-CSF-mobilized cells, as opposed to an upregulation of cell cycle-promoting genes including Cyclin D2 and Hepatocyte Leukemia Factor (HLF) in pegfilgrastim-mobilized cells. Moreover in pegfilgrastim-mobilized CD34+ cells we saw an upregulation of multiple genes involved in cellular immunogenicity like MHC class I and II antigens and genes encoding for proteins playing a role in antigen presentation. Conclusion: Unconjugated G-CSF seems to be associated with an increased mobilisation of erythroid progenitors or an induction of erythropoiesis. Pegfilgrastim might result in mobilization of more immunogenic CD34+ cells. Unconjugated G-CSF and pegfilgrastim both seem to have an effect on cell cycle. Unconjugated G-CSF might rather induce cell cycle arrest and pegfilgrastim seems to lead to an increase of the cell cycle activity. This may be due to potentially different effects of continuously high serum levels of G-CSF maintained by pegfilgrastim and the pulsatile daily G-CSF injections on CD34+ cells.

TRAIL Preferentially Affects Cell Cycle-Arrested Tumor Cells Including Stem- and Progenitor Cells From Patients with Acute Lymphoblastic Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1879-1879 ◽  
Author(s):  
Harald Ehrhardt ◽  
Catarina Castro Alves ◽  
Franziska Wachter ◽  
Irmela Jeremias
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Progenitor Cells ◽  
Tumor Cells ◽  
Lymphoblastic Leukemia ◽  
Cytotoxic Drugs ◽  
Cycle Arrest ◽  
Stem And Progenitor Cells ◽  
Induced Apoptosis ◽  
Anti Tumor Activity

Abstract Abstract 1879 Leukemic stem- and progenitor cells exhibit low cycling activity which might represent a major cause for their increased treatment resistance. TRAIL (TNF-related apoptosis inducing ligand) is a novel putative anticancer drug currently in phase I and II clinical testing. We recently showed that TRAIL is able to address stem- and progenitor cells from patients with acute lymphoblastic leukemia (ALL) in xenotransplantation assays (Alves et al., Blood 2012,119,4224). As stem- and progenitor cells are often non-cycling, we asked here, whether TRAIL is able to address resting leukemia cells. We used cell lines and primary tumor cells from children with ALL which were amplified in severely immuno-compromised mice (NSG mice). Cell cycle arrest was induced (i) by addition of conventional cytotoxic drugs which are known to act as cytostatic drugs such as doxorubicine; (ii) by biochemical inhibitors known to induce cell cycle arrest at different defined points of the cell cycle such as mimosine; (iii) by molecular approaches and knockdown of cyclinB arresting cell cycle in G2 or knockdown of cyclinE arresting cell cycle in G1. Unexpectedly, TRAIL-induced apoptosis was enhanced, whenever cell cycle was arrested. Cell cycle arrest sensitized towards TRAIL-induced apoptosis independently from the point or phase of cell cycle which was arrested (G0, G1 or G2) and independently from the agent used to arrest the cell cycle. Similarly, knockdown of cyclinB or cyclinE both clearly sensitized cell line cells towards TRAIL-induced apoptosis. Cytotoxic drugs and cell cycle inhibitors might arrest the cell cycle by activation of p53. Accordingly, when caffeine was added which inhibited p53 activity and drug-induced cell cycle arrest, sensitization towards TRAIL-induced apoptosis was blocked. We have recently established a novel method which enables performing knockdown experiments in tumor cells derived from ALL patients (Höfig et al., Cell Comm. Signal. 2012,10,8). Using this method and most important for clinical translation, we could show that knockdown of either cyclinB or cyclinE clearly sensitized patient-derived ALL cells towards TRAIL-induced apoptosis. Taken together and in contrast to most conventional cytotoxic drugs, TRAIL exerts anti-tumor activity preferentially against tumor cells in cell cycle arrest and less against actively cycling tumor cells. This special feature of TRAIL might explain its anti-tumor activity against stem- and progenitor cells in patients with ALL. Thus, TRAIL might represent an interesting drug to treat disease stages with accumulation of stem- and progenitor cells and static tumor disease, e.g., during minimal residual disease. Disclosures: No relevant conflicts of interest to declare.

scholarly journals 8-Chloroadenosine 3′,5′-monophosphate induces cell cycle arrest and apoptosis in multiple myeloma cells through multiple mechanisms

2012 ◽  
Vol 4 (6) ◽  
pp. 1384-1388 ◽  
Author(s):  
YI-MIN CHENG ◽  
QI ZHU ◽  
YI-YUN YAO ◽  
YONG TANG ◽  
MING-MING WANG ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Cell Cycle Arrest ◽  
Myeloma Cells ◽  
Cycle Arrest

scholarly journals The insulin-like growth factor-I receptor inhibitor NVP-AEW541 provokes cell cycle arrest and apoptosis in multiple myeloma cells

2008 ◽  
Vol 141 (4) ◽  
pp. 470-482 ◽  
Author(s):  
Patricia Maiso ◽  
Enrique M. Ocio ◽  
Mercedes Garayoa ◽  
Juan C. Montero ◽  
Francesco Hofmann ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Growth Factor ◽  
Cell Cycle Arrest ◽  
Insulin Like Growth Factor ◽  
Myeloma Cells ◽  
Factor I ◽  
Cycle Arrest ◽  
Growth Factor I ◽  
Receptor Inhibitor

scholarly journals Induction of Apoptosis, Autophagy and Ferroptosis by Thymus vulgaris and Arctium lappa Extract in Leukemia and Multiple Myeloma Cell Lines

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5016
Author(s):  
Aveen N. Adham ◽  
Mohamed Elamir F. Hegazy ◽  
Alaadin M. Naqishbandi ◽  
Thomas Efferth
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Cell Death ◽  
Ethyl Acetate ◽  
Cell Cycle Arrest ◽  
Cell Lines ◽  
Thymus Vulgaris ◽  
Arctium Lappa ◽  
Cycle Arrest ◽  
Induction Of Apoptosis

Thymus vulgaris and Arctium lappa have been used as a folk remedy in the Iraqi Kurdistan region to deal with different health problems. The aim of the current study is to investigate the cytotoxicity of T. vulgaris and A. lappa in leukemia and multiple myeloma (MM) cell lines and determine the mode of cell death triggered by the most potent cytotoxic fractions of both plants in MM. Resazurin assay was used to evaluate cytotoxic and ferroptosis activity, apoptosis, and modulation in the cell cycle phase were investigated via Annexin V-FITC/PI dual stain and cell-cycle arrest assays. Furthermore, we used western blotting assay for the determination of autophagy cell death. n-Hexane, chloroform, ethyl acetate, and butanol fractions of T. vulgaris and A. lappa exhibited cytotoxicity in CCRF-CEM and CEM/ADR 5000 cell lines at concentration range 0.001–100 μg/mL with potential activity revealed by chloroform and ethyl acetate fractions. NCI-H929 displayed pronounced sensitivity towards T. vulgaris (TCF) and A. lappa (ACF) chloroform fractions with IC50 values of 6.49 ± 1.48 and 21.9 ± 0.69 μg/mL, respectively. TCF induced apoptosis in NCI-H929 cells with a higher ratio (71%), compared to ACF (50%) at 4 × IC50. ACF demonstrated more potent autophagy activity than TCF. TCF and ACF induced cell cycle arrest and ferroptosis. Apigenin and nobiletin were identified in TCF, while nobiletin, ursolic acid, and lupeol were the main compounds identified in ACF. T. vulgaris and A. lappa could be considered as potential herbal drug candidates, which arrest cancer cell proliferation by induction of apoptosis, autophagic, and ferroptosis.

DCZ0801, a novel compound, induces cell apoptosis and cell cycle arrest via MAPK pathway in multiple myeloma

2019 ◽  
Vol 51 (5) ◽  
pp. 517-523 ◽  
Author(s):  
Ting Zhang ◽  
Bo Li ◽  
Qilin Feng ◽  
Zhijian Xu ◽  
Cheng Huang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Cell Cycle Arrest ◽  
Cell Apoptosis ◽  
Mapk Pathway ◽  
Cycle Arrest

Enforced Expression of GATA-2 Confers Quiescence on Human Hematopoietic Stem and Progenitor Cells In Vitro and In Vivo.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 83-83
Author(s):  
Alex J. Tipping ◽  
Cristina Pina ◽  
Anders Castor ◽  
Ann Atzberger ◽  
Dengli Hong ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Progenitor Cells ◽  
Zinc Finger ◽  
Human Cord Blood ◽  
Hematopoietic Stem ◽  
Cd34 Cells ◽  
Stem And Progenitor Cells ◽  
Colony Number

Abstract Hematopoietic stem cells (HSCs) in adults are largely quiescent, periodically entering and exiting cell cycle to replenish the progenitor pool or to self-renew, without exhausting their number. Expression profiling of quiescent HSCs in our and other laboratories suggests that high expression of the zinc finger transcription factor GATA-2 correlates with quiescence. We show here that TGFβ1-induced quiescence of wild-type human cord blood CD34+ cells in vitro correlated with induction of endogenous GATA-2 expression. To directly test if GATA-2 has a causative role in HSC quiescence we constitutively expressed GATA-2 in human cord blood stem and progenitor cells using lentiviral vectors, and assessed the functional output from these cells. In both CD34+ and CD34+ CD38− populations, enforced GATA-2 expression conferred increased quiescence as assessed by Hoechst/Pyronin Y staining. CD34+ cells with enforced GATA-2 expression showed reductions in both colony number and size when assessed in multipotential CFC assays. In CFC assays conducted with more primitive CD34+ CD38− cells, colony number and size were also reduced, with myeloid and mixed colony number more reduced than erythroid colonies. Reduced CFC activity was not due to increased apoptosis, as judged by Annexin V staining of GATA-2-transduced CD34+ or CD34+ CD38− cells. To the contrary, in vitro cultures from GATA-2-transduced CD34+ CD38− cells showed increased protection from apoptosis. In vitro, proliferation of CD34+ CD38− cells was severely impaired by constitutive expression of GATA-2. Real-time PCR analysis showed no upregulation of classic cell cycle inhibitors such as p21, p57 or p16INK4A. However GATA-2 expression did cause repression of cyclin D3, EGR2, E2F4, ANGPT1 and C/EBPα. In stem cell assays, CD34+ CD38− cells constitutively expressing GATA-2 showed little or no LTC-IC activity. In xenografted NOD/SCID mice, transduced CD34+ CD38−cells expressing high levels of GATA-2 did not contribute to hematopoiesis, although cells expressing lower levels of GATA-2 did. This threshold effect is presumably due to DNA binding by GATA-2, as a zinc-finger deletion variant of GATA-2 shows contribution to hematopoiesis from cells irrespective of expression level. These NOD/SCID data suggest that levels of GATA-2 may play a part in the in vivo control of stem and progenitor cell proliferation. Taken together, our data demonstrate that GATA-2 enforces a transcriptional program on stem and progenitor cells which suppresses their responses to proliferative stimuli with the result that they remain quiescent in vitro and in vivo.

The Histone Deacetylase Inhibitor LAQ824 Maintains Normal Hematopoietic Progenitor cells (HPC) Associated with Induction of Notch Target Genes and Does Not Eliminate Leukemic HPC in Vitro.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1352-1352
Author(s):  
Kerstin Schwarz ◽  
Oliver Ottmann ◽  
Annette Romanski ◽  
Anja Vogel ◽  
Jeffrey W. Scott ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Progenitor Cells ◽  
Gene Expression Analysis ◽  
Target Genes ◽  
Notch Pathway ◽  
Cycle Arrest ◽  
Cd34 Cells ◽  
20 Nm

Abstract Introduction: Histone deacetylase inhibitors (DACi) have shown promising antileukemic activity by overcoming the differentiation block and inducing apoptosis in AML blasts. Recent data demonstrating enhanced maintenance and functional capacity of normal, but also leukemic hematopoietic progenitor cells (HPC) by the selective class I DACi valproic acid (VPA) have raised concerns about VPA in AML therapy. As more potent pan-DACi have entered clinical trials, we analysed the impact of the hydroxamic acid LAQ824 on phenotype and function of normal and leukemic CD34+ HPC and studied LAQ824- induced gene expression in the most primitive CD34+CD38- population of normal HPC. Methods: Differentiation and proliferation of CD34+ cells of bone marrow of healthy donors and peripheral blood samples of newly diagnosed AML patients were evaluated after one week of culture in presence of SCF, FLT3 ligand, TPO, IL-3 +/− LAQ824. The effect of LAQ824 on gene expression profiles in normal CD34+CD38− cells was assessed in three independent cell samples following incubation with cytokines +/− LAQ824 for 48 hours using Affymetrix GeneChip Human Genome U133 Plus 2.0 and Gene Spring Software. Serial replating of murine Sca1+Lin- HPC was performed in the presence of SCF, G-CSF, GM-CSF, IL-3, IL-6 +/− LAQ824. Results: Treatment of murine Sca1+Lin- HPC with LAQ824 (10 nM) significantly augmented colony numbers (p<0.01; n=3), and supported colony growth after four cycles of replating whereas no colonies developed in its absence beyond the second plating indicating preservation of functionally active multipotent progenitor cells. LAQ824 (10–20 nM) mediated acetylation of histone H3 in human normal and leukemic HPC. In normal HPC, LAQ824 (0–20 nM) lead to a dose-dependent increase in the proportion of CD34+ cells (20% w/o LAQ824 vs. 36% with LAQ824 20nM, p=0.07) and a significant reduction of CD14+ monocytes (18% vs. 3%, p= 0.02; n=3). The total number of CD34+ cells remained stable up to 10 nM and decreased at 20 nM. Gene expression analysis showed, that LAQ824 (20 nM) lead to an at least 3-fold up-regulation of 221 genes in all three HPC samples tested including HDAC11 and the cell cycle inhibitor p21waf1/cip1 known to be induced by most DACi in HPC. We identified several members of the notch pathway such as mastermind-like protein 2 (MAML2, a component of the active notch transcriptional complex) and notch target genes including the transcription factors HES1, HEY1 and HOXA10 and confirmed increase of protein levels by Western blotting. Reduced gene expression of mini-chromosome-maintenance (MCM) protein family members was observed which - in addition to up-regulation of p21 - has previously been associated with notch-mediated cell cycle arrest. To compare the effect of LAQ824 (20 nM) with VPA (150 ng/ml) on leukemic HPC, cells were cultured for one week with or w/o DACi. Of note, LAQ824 resulted in a 0.8-fold reduction of CD34+ leukemic HPC, while VPA expanded this population 2.2-fold compared with cytokine-treated controls (p=0.03; n=12). CFU numbers growing from CD34+ leukemic HPC in presence of LAQ824 did not differ significantly from controls (n=9). Conclusion: LAQ824 seems to diminish, but not eliminate normal as well as leukemic HPC as determined by phenotypic and functional in vitro analyses. Our gene expression analysis suggested an association with coactivator and target genes of the notch pathway and cell cycle arrest-inducing genes. In contrast to VPA, LAQ824 does not seem to support growth of leukemic HPC which may contribute to its more potent antileukemic effect.

Elevated EGR2 Expression Provides a Potential Link Between Cell Cycle Arrest and Induced Differentiation in Myeloid Progenitor Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2733-2733
Author(s):  
Joshua B. Bland ◽  
Jose R. Peralta ◽  
William T. Tse
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Progenitor Cells ◽  
Myeloid Differentiation ◽  
Phenotypic Effect ◽  
Induced Differentiation ◽  
Hl60 Cells ◽  
Cycle Arrest ◽  
Myeloid Progenitor ◽  
Myeloid Progenitor Cells

Abstract Similar to many immature cell types, myeloid progenitor cells need to exit cell cycle to undergo terminal differentiation, but the mechanism linking the two is still unclear. Elucidating this mechanism could lead to the development of new differentiation therapies to treat myeloid leukemia. Recent studies have suggested that the processes regulating myeloid differentiation and cell cycle progression together constitute a positive feedback loop where each process reciprocally affects the other. To study the relationship between these processes, we examined early cellular and molecular events associated with induced differentiation of the HL60 human promyelocytic leukemia cells. We treated HL60 cells with 3 classical inducers of differentiation (vitamin D3 analog EB1089 (EB), all-trans retinoic acid (ATRA), and dimethyl sulfoxide (DMSO)), along with PD0332991 (PD), a selective cyclin D-dependent kinase 4/6 inhibitor that caused G1-phase-specific cell-cycle arrest. We evaluated differentiation of the treated cells by flow cytometric analysis of CD11b (integrin αM) and CD71 (transferrin receptor) expression. In untreated HL60 cells, a baseline subset of 3-5% of cells exhibits a differentiated, CD11b+CD71- phenotype. Exposure to the various inducers revealed a progressive increase in the percentage of CD11b+CD71- cells with time, such that by day 4 of treatment, it has increased to 50-90% in the treated samples, indicating that all 4 agents tested were effective in inducing myeloid differentiation. To understand how differentiation induced by each agent affects cell cycle progression, the cell cycle status of the induced cells were evaluated by a BrdU-incorporation assay after a 30-minute pulse of BrdU labeling. Uninduced cells exhibited a baseline cell cycle phase distribution of 64%-28%-8% (G1-S-G2/M phases). After 1 day of induction, EB-treated sample showed no changes in the distribution (58%-33%-9%), but ATRA, DMSO and PD-treated samples showed significant changes, with an increase of cell numbers in G1 phase and decrease in S phase (74%-18%-8%, 79%-13%-8%, and 93%-4%-3%, respectively). These results reveal that an early induction of G1 arrest was caused by treatment with ATRA, DMSO and PD, but not EB, and that the cell cycle arrest occurred before major changes in the myeloid phenotype were observed. To determine how the cell cycle perturbation relates to changes in the underlying genetic regulatory network, we examined by quantitative RT-PCR analysis the expression of several transcription factors associated with myeloid differentiation. PU.1 and CEBPA were found to be expressed at high levels but these levels did not change upon treatment with the inducing agents. Similarly, the expression levels of GFI1 and EGR1 did not change significantly with induction. In contrast, the expression level of EGR2 (Early Growth Response 2) was found to be low initially but became elevated upon treatment with 3 of the 4 inducers. EGR2 is a zinc finger transcription factor implicated in the control of a switch between pro- and anti-proliferation pathways. EGR2 has been shown to regulate the transition between differentiation states of Schwann cells, induction of anergic and regulatory T cells, growth and survival of osteoclasts, and proliferation and apoptosis of acute myeloid leukemia blasts. We found that EGR2 expression, after 1 day of treatment with ATRA, DMSO or PD, was increased by 5.2 ± 0.9, 7.6 ± 1.9, 5.8 ± 0.9 folds, respectively, whereas treatment with EB led to no significant change (1.5 ± 0.2 fold). We evaluated whether simultaneous treatment of the cells with 2 inducers would result in an additive effect. Treatment of HL60 cells with a combination of ATRA/DMSO, ATRA/PD, or DMSO/PD increased the percentage of CD11b+CD71- cells to 55%, 70% and 25% after just 1 day of treatment. In line with the enhanced phenotypic effect, the expression level of EGR2 was further elevated to 7.7 ± 1.4, 15.4 ± 3.5, and 11.3 ± 3.4 folds, respectively, when the cells were treated with the above inducer combinations, indicating a tight association between EGR2 expression and the phenotypic effect. In summary, our data suggest that elevated expression of EGR2 is an early event in the induction of myeloid differentiation in HL60 cells. Because of its known role in cell cycle regulation, EGR2 could function as a mechanistic link between cell cycle arrest and induced differentiation in myeloid progenitor cells. Disclosures No relevant conflicts of interest to declare.

Capsaicin induces G1/S cell cycle arrest leading to apoptosis of multiple myeloma cells through suppression of STAT3 activation and STAT3-regulated gene products

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 20039-20039
Author(s):  
M. Bhutani ◽  
A. K. Pathak ◽  
G. Sethi ◽  
B. B. Aggarwal
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Cyclin D1 ◽  
Cell Cycle Arrest ◽  
Hot Pepper ◽  
Dependent Manner ◽  
Antiapoptotic Proteins ◽  
Cycle Arrest ◽  
Stat3 Phosphorylation ◽  
Synergistic Cytotoxicity

20039 Background: Agents that can block activated STAT3, a central player for proliferation, cell survival and chemoresistance, have a potential as therapeutic agents for the treatment of Multiple Myeloma (MM). Capsaicin, a spicy component of hot pepper, is a homovanillic acid derivative that preferentially induces certain cancer cells to undergo apoptosis. We have previously shown that Capsaicin blocked activation of NF-kappa B in human myeloid ML-1a cells. In this study we evaluated the effect of Capsaicin on STAT3 in MM cells. Methods: We used U266, a well-characterized MM cell line, which constitutively expresses activated STAT3. MM cells treated with Capsaicin were subjected to western blot analysis with specific antibodies to STAT3, tyrosyl phosphorylated STAT3 and STAT5. The effect of Capsaicin on nuclear-cytoplasmic compartment of STAT3 was studied by immunocytochemistry. The antiproliferative effect of Capsaicin was determined by the MTT assay and the effect on the cell cycle was determined by flowcytometry. Apoptosis of cells was measured using the Live and Dead assay. To determine the downstream targets like antiapoptotic proteins (Bcl-xL, Bcl-2, and Survivin), and cell cycle-regulators (cyclin D1) immunoblot analysis of Capsaicin treated cells was performed. Results: Capsaicin suppressed the constitutive activation of STAT3 in human MM cells in a dose- and time-dependent manner, prior to cell death. Capsaicin’s effect on STAT3 was specific as STAT5 was unaffected. Capsaicin depleted nuclear pool of STAT3 in U266 cells. Abrogation of constitutive STAT3 phosphorylation in MM cells induced G1 cell cycle arrest. The antiapoptotic proteins BCl-xl, suvivin, cyclin D1, and Bcl-2, which are encoded in target genes of STAT3, were down regulated by Capsaicin, followed by induction of apoptosis through activation of caspase-3. We further demonstrated that low dose combined Capsaicin and thalidomide/ bortezomib treatment triggered synergistic cytotoxicity. Conclusions: These findings suggest that the antitumor activity of Capsaicin is at least partially due to inhibition of STAT3 pathway and provide a basis for potential application of Capsaicin for treatment of relapsed and refractory MM. No significant financial relationships to disclose.

Sign in / Sign up

Export Citation Format

Share Document