Multiomics of azacitidine-treated AML cells reveals variable and convergent targets that remodel the cell-surface proteome.

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are diseases of abnormal hematopoietic differentiation with aberrant epigenetic alterations. Azacitidine (AZA) is a DNA methyltransferase inhibitor widely used to treat MDS and AML, yet the impact of AZA on the cell-surface proteome has not been defined. To identify potential therapeutic targets for use in combination with AZA in AML patients, we investigated the effects of AZA treatment on four AML cell lines representing different stages of differentiation. The effect of AZA treatment on these cell lines was characterized at three levels: the DNA methylome, the transcriptome, and the cell-surface proteome. Untreated AML cell lines showed substantial overlap at all three omics levels; however, while AZA treatment globally reduced DNA methylation in all cell lines, changes in the transcriptome and surface proteome were subtle and differed among the cell lines. Transcriptome analysis identified five commonly up-regulated coding genes upon AZA treatment in all four cell lines, TRPM4 being the only gene encoding a surface protein, and surface proteome analysis found no commonly regulated proteins. Gene set enrichment analysis of differentially regulated RNA and surface proteins showed a decrease in metabolic pathways and an increase in immune defense response pathways. As such, AZA treatment led to diverse effects at the individual gene and protein levels but converged to common responses at the pathway level. Given the heterogeneous responses in the four cell lines, we discuss potential therapeutic strategies for AML in combination with AZA.

Pretreatment with ibrutinib reduces cytokine secretion and limits the risk of obinutuzumab-induced infusion-related reactions in patients with CLL: analysis from the iLLUMINATE study.

Anti-CD20 antibody treatments, such as obinutuzumab, have been associated with infusion-related reactions (IRRs). In the phase 3 iLLUMINATE study of ibrutinib-obinutuzumab versus chlorambucil-obinutuzumab in first-line chronic lymphocytic leukemia/small lymphocytic lymphoma, IRRs were substantially reduced with ibrutinib-obinutuzumab versus chlorambucil-obinutuzumab. We prospectively analyzed inflammatory cytokines to evaluate the impact of ibrutinib on circulating cytokine levels following obinutuzumab infusion. In iLLUMINATE, ibrutinib or chlorambucil was given approximately 30-120 min before the first obinutuzumab infusion. Cytokines evaluated were IFNγ, IL-6, IL-8, IL-10, IL-18, MCP-1, MIP-1α, MIP-1ß, and TNFα. Changes in peak cytokine levels from baseline (immediately before obinutuzumab) to post-obinutuzumab infusion were compared between arms and between patients with versus without IRRs using Wilcoxon rank sum test. Of 228 treated patients, 95 on ibrutinib-obinutuzumab (15 with IRRs, 80 without) and 88 on chlorambucil-obinutuzumab (45 with IRRs, 43 without) with cytokine data were included. Irrespective of IRR occurrence, median increase in cytokines was lower with ibrutinib-obinutuzumab versus chlorambucil-obinutuzumab for all cytokines (P < 0.01) except MIP-1ß. Across treatment arms, post-obinutuzumab median increase in all cytokines except MIP-1ß was greater in patients with versus without IRRs (P < 0.001). IL-6 and IL-8 elevations were associated with IRRs in both treatment arms. Among patients with IRRs, those receiving ibrutinib-obinutuzumab had lower post-obinutuzumab increases in IL-6, IL-8, IL-10, and MCP-1 (P < 0.04) than patients receiving chlorambucil-obinutuzumab. For patients in the ibrutinib-treatment arm, we observed a reduction in both the rate of clinically apparent IRRs and the levels of IRR-related cytokines and chemokines. This observation supports an immunomodulatory mechanism of action for ibrutinib. Clinical Trial Registration: NCT02264574.

Discovery of bicyclic pyrazoles as class III histone deacetylase SIRT1 and SIRT2 inhibitors.

A series of bicyclic pyrazole carboxamides was synthesized and tested for inhibitory activity against the class III deacetylase sirtuin enzymes. Moderate to low micromolar inhibitory activities were obtained against SIRT1 and SIRT2. These bicyclic pyrazole compounds represent a new class of sirtuin inhibitors with a preference for SIRT1 over SIRT2.

Quality of Life After Pediatric Tympanomastoidectomy.

OBJECTIVES: To assess quality of life (QOL) outcomes after canal wall up (CWU) and canal wall down (CWD) tympanomastoidectomy in the pediatric population. METHODS: A retrospective review tabulated pediatric patients undergoing CWU and CWD tympanomastoidectomy for cholesteatoma by 2 senior surgeons at a single tertiary academic referral center between March 2017 and March 2023. Chronic Ear Survey (CES) and cosmetic survey outcomes were collected post-operatively. RESULTS: A total of 77 ears in 75 patients were identified, with 35 undergoing CWU and 42 undergoing CWD as the most recent (index) otologic surgery. Seventeen patients (23%) participated in the survey. Of this cohort, the mean age was 14.6 years, 12 (71%) were male, and 10 (59%) had CWD as the most recent otologic surgery. The mean time from index surgery to survey completion was 3.4 years (range, 0.1-6.7 years). Regarding QOL outcomes, there were no statistically significant differences in total CES score, CES subscores, and cosmetic survey scores between groups when categorizing by gender or index surgery. Total CES, symptom subscale, medical resource subscale, and cosmetic survey scores showed a tendency to decrease with an increasing number of surgeries (R = -.18, -.28, -.53, and -.56, respectively). Pediatric total CES scores appeared comparable to those reported in the published adult literature. CONCLUSIONS: It does not appear that there are worse QOL outcomes for pediatric patients who undergo CWD tympanomastoidectomy compared to those who undergo CWU tympanomastoidectomy. There appears to be no difference in QOL outcomes between pediatric and adult patients undergoing tympanomastoidectomy.

Increasing digital equity to promote online smoking cessation program engagement among rural adults: a randomized controlled pilot trial.

BACKGROUND: Cigarette smoking prevalence is higher for rural than urban adults, yet digital access to cessation programming is reduced. We aim to investigate digital access interventions to promote engagement with an online evidence-based cessation treatment (EBCT) program among rural adults. METHODS: This pilot trial used a pragmatic, three-arm, randomized, parallel-group design (ClinicalTrials.gov: NCT05209451). Inclusion criteria included being aged ≥18, Mayo Clinic Midwest patient, rural residency, and currently smokes cigarettes. All participants received an online, 12-week EBCT program and were randomized to receive one of three digital access interventions: print materials (control, n = 30); print materials + loaner iPad device with data plan coverage (n = 30); or print materials + loaner device + up to six, 15-20-minute motivational interviewing-based coaching calls to support technology needs (n = 30). A composite score of trial engagement (primary outcome) and self-reported smoking abstinence and use of EBCT resources (secondary outcomes) were assessed online at 4 and 12 weeks. Qualitative interviews were used to assess patient experience. Neither participants nor outcome assessors were blinded to group assignment. RESULTS: Results are reported for all 30 participants in each group. The average age of participants is 51.0 years and 61% are women. We show no significant arm differences for the trial engagement composite score (p = 0.30). We also find coaching support is significantly (p < 0.05) associated with enhanced smoking-related treatment response, including cigarette abstinence and use of EBCT resources, and participants reported positive experiences with the intervention. CONCLUSIONS: The coaching intervention to support technology needs is acceptable and shows preliminary evidence of its efficacy in smoking-related treatment response. Further studies could refine and implement the coaching intervention for trial engagement and long-term cessation.

More adults smoke cigarettes in rural than urban adults, yet there is less access to effective digital tools to assist people to quit smoking in rural areas. We compared three strategies to promote engagement with an online program to encourage rural adults to quit smoking. The three interventions were: print materials; print materials plus a loaner iPad device with data plan coverage; or print materials and loaner device, plus up to six, 15­20-minute individualized coaching calls to support technology needs. We found that individuals receiving the coaching support had improved smoking-related outcomes. Our study provides a better understanding of the resources needed to support digital access in rural populations and the results could be used to improve approaches to encourage people living in rural areas to stop smoking.

The what matters most survey: A measurement evaluation of a self-reported patient values elicitation tool among cancer survivors.

OBJECTIVES: Patients with multiple chronic conditions, especially cancer survivors, face challenges in medical decision making. Previous research demonstrates how patient values can guide medical decisions, however facilitating patient values elicitation remains a challenge. This study aims to evaluate the psychometric properties of and refine the What Matters Most (WMM) Survey, a self-reported values elicitation tool, in a cohort of older veteran cancer survivors. METHODS: An observational cohort study was conducted to evaluate the psychometric properties of the WMM Survey in older, multimorbid cancer survivors. 262 patients were administered the assessment at two timepoints, between 14 and 30 days apart. RESULTS: Exploratory factor analyses revealed four factors for assessing healthcare values among older adults with good internal consistency for all factors: Functioning (Cronbach's alpha coefficient, α = 0.88), Enjoying Life (α = 0.79), Connecting (α = 0.84), and Managing Health (α = 0.88). Demographic and clinical characteristics were not uniformly associated with specific healthcare values. CONCLUSIONS: Future studies are required to refine the proposed assessment and to evaluate its application in a general patient population. PRACTICE IMPLICATIONS: The WMM Survey is an innovative resource in health values elicitation, allowing for facilitation of patient-clinician communication for whole-person medical approaches and measurement of health values for research.

Elevated Hoxb5b Expands Vagal Neural Crest Pool and Blocks Enteric Neuronal Development in Zebrafish.

Neural crest cells (NCCs) are a migratory, transient, and multipotent stem cell population essential to vertebrate embryonic development, contributing to numerous cell lineages in the adult organism. While great strides have been made in elucidating molecular and cellular events that drive NCC specification, comprehensive knowledge of the genetic factors that orchestrate NCC developmental programs is still far from complete. We discovered that elevated Hoxb5b levels promoted an expansion of zebrafish NCCs, which persisted throughout multiple stages of development. Correspondingly, elevated Hoxb5b also specifically expanded expression domains of the vagal NCC markers foxd3 and phox2bb. Increases in NCCs were most apparent after pulsed ectopic Hoxb5b expression at early developmental stages, rather than later during differentiation stages, as determined using a novel transgenic zebrafish line. The increase in vagal NCCs early in development led to supernumerary Phox2b+ enteric neural progenitors, while leaving many other NCC-derived tissues without an overt phenotype. Surprisingly, these NCC-derived enteric progenitors failed to expand properly into sufficient quantities of enterically fated neurons and stalled in the gut tissue. These results suggest that while Hoxb5b participates in vagal NCC development as a driver of progenitor expansion, the supernumerary, ectopically localized NCC fail to initiate expansion programs in timely fashion in the gut. All together, these data point to a model in which Hoxb5b regulates NCCs both in a tissue specific and temporally restricted manner.

Inhibition of the TGF-beta receptor I kinase promotes hematopoiesis in MDS.

MDS is characterized by ineffective hematopoiesis that leads to peripheral cytopenias. Development of effective treatments has been impeded by limited insight into pathogenic pathways governing dysplastic growth of hematopoietic progenitors. We demonstrate that smad2, a downstream mediator of transforming growth factor-beta (TGF-beta) receptor I kinase (TBRI) activation, is constitutively activated in MDS bone marrow (BM) precursors and is overexpressed in gene expression profiles of MDS CD34(+) cells, providing direct evidence of overactivation of TGF-beta pathway in this disease. Suppression of the TGF-beta signaling by lentiviral shRNA-mediated down-regulation of TBRI leads to in vitro enhancement of hematopoiesis in MDS progenitors. Pharmacologic inhibition of TBRI (alk5) kinase by a small molecule inhibitor, SD-208, inhibits smad2 activation in hematopoietic progenitors, suppresses TGF-beta-mediated gene activation in BM stromal cells, and reverses TGF-beta-mediated cell-cycle arrest in BM CD34(+) cells. Furthermore, SD-208 treatment alleviates anemia and stimulates hematopoiesis in vivo in a novel murine model of bone marrow failure generated by constitutive hepatic expression of TGF-beta1. Moreover, in vitro pharmacologic inhibition of TBRI kinase leads to enhancement of hematopoiesis in varied morphologic MDS subtypes. These data directly implicate TGF-beta signaling in the pathobiology of ineffective hematopoiesis and identify TBRI as a potential therapeutic target in low-risk MDS.

p38alpha-selective MAP kinase inhibitor reduces tumor growth in mouse xenograft models of multiple myeloma.

Multiple myeloma (MM) is a clonal plasma cell malignancy, which is currently incurable. Therefore, new mono- or combined therapy treatment regimens in the early and advanced phases of MM are urgently needed to combat this disease. Recently, p38 mitogen-activated protein kinase (MAPK) has been implicated as playing an important role in MM. Therefore, the effect of a p38alpha-selective MAPK inhibitor, SCIO-469 (indole-5-carboxamide, ATP-competitive inhibitor), or its structural analog, SD-282 (indole-5-carboxamide, ATP-competitive inhibitor) was examined in mouse xenograft models of MM using human RPMI-8226 or H-929 plasmacytoma inocula. Oral treatment with SCIO-469 (10, 30, 90 mg/kg) twice daily was initiated in mice with palpable tumors of RPMI-8226 origin, a condition that mimics early human myeloma disease. In mice with palpable tumors, 14 days of SCIO-469 treatment significantly reduced RPMI-8226 tumor growth in a dose-dependent manner. A significant dose-dependent reduction in RPMI-8226 tumor growth was also observed when SCIO-469 oral treatment at doses of 10, 30 and 90 mg/kg twice daily was initiated in mice with tumors of pronounced size, a condition that mimics advanced human myeloma disease. In a similar set of studies employing the SCIO-469 analogue SD-282 at 90 mg/kg/bid orally, histological assessment at the end of the study demonstrated a significant reduction in RPMI-8226 tumor growth and angiogenesis. SD-282 treatment was additionally shown to significantly reduced expression of heat-shock protein-27 (HSP-27) and phospho-p38 in the tumor cells. Furthermore, co-administration of SCIO-469 with dexamethasone elicited antitumor properties in dexamethasone-sensitive H-929 tumors at much lower than the typically effective doses of dexamethasone, suggesting its potential for combined therapy. In conclusion, p38 inhibitors reduced human myeloma cell growth in vivo both at early and advanced phases of the disease. The current study also provides evidence of potential for co-therapy with dexamethasone.

Pharmacological properties of SD-282 - an alpha-isoform selective inhibitor for p38 MAP kinase.

The effects of small-molecule p38 inhibitors in numerous models of different disease states have been published, including those of SD-282, an indole-5-carboxamide inhibitor. The aim of the present study was to evaluate the pharmacological activity of SD-282 on cytokine production in vitro as well as in 2 in vivo models of inflammation in order to illuminate the role of this particular inhibitor in diverse disease states. The results presented here provide further characterization of SD-282 and provide a context in which to interpret the activity of this p38 inhibitor in models of arthritis, pain, myocardial injury, sepsis and asthma; all of which have an inflammatory component. SD-282 represents a valuable tool to elucidate the role of p38 MAP kinase in multiple models of inflammation.

Phase I Study of CC-486 Alone and in Combination with Carboplatin or nab-Paclitaxel in Patients with Relapsed or Refractory Solid Tumors.

Purpose: This large two-part, three-arm phase I study examined the safety and tolerability of CC-486 (an oral formulation of azacitidine, a hypomethylating agent) alone or in combination with the cytotoxic agents, carboplatin or nab-paclitaxel, in patients with advanced unresectable solid tumors.Patients and Methods: Part 1 (n = 57) was a dose escalation of CC-486 alone (arm C) or with carboplatin (arm A) or nab-paclitaxel (arm B). The primary endpoint was safety, MTD, and recommended part 2 dose (RP2D) of CC-486. In part 2 (n = 112), the primary endpoint was the safety and tolerability of CC-486 administered at the RP2D for each treatment arm, in tumor-specific expansion cohorts. Secondary endpoints included pharmacokinetics, pharmacodynamics, and antitumor activity of CC-486.Results: At pharmacologically active doses CC-486 in combination with carboplatin or nab-paclitaxel had a tolerable safety profile and no drug-drug interactions. The CC-486 RP2D was determined as 300 mg (every day, days 1-14/21) in combination with carboplatin (arm A) or as monotherapy (arm C); and 200 mg in the same dosing regimen in combination with nab-paclitaxel (arm B). Albeit limited by the small sample size, CC-486 monotherapy resulted in partial responses (three/eight) and stable disease (four/eight) in patients with nasopharyngeal cancer. Three of the stable disease responses lasted more than 150 days.Conclusions: CC-486 is well tolerated alone or in combination with carboplatin or nab-paclitaxel. Exploratory analyses suggest clinical activity of CC-486 monotherapy in nasopharyngeal cancer and provided the basis for an ongoing phase II clinical trial (ClinicalTrials.gov identifier: NCT02269943). Clin Cancer Res; 24(17); 4072-80. ©2018 AACR.

Cytoplasmic localization of Wis1 MAPKK by nuclear export signal is important for nuclear targeting of Spc1/Sty1 MAPK in fission yeast.

Mitogen-activated protein kinase (MAPK) cascade is a ubiquitous signaling module that transmits extracellular stimuli through the cytoplasm to the nucleus; in response to activating stimuli, MAPKs translocate into the nucleus. Mammalian MEK MAPK kinases (MAPKKs) have in their N termini an MAPK-docking site and a nuclear export signal (NES) sequence, which are known to play critical roles in maintaining ERK MAPKs in the cytoplasm of unstimulated cells. Herein, we show that the Wis1 MAPKK of the stress-activated Spc1 MAPK cascade in fission yeast also has a MAPK-docking site and an NES sequence in its N-terminal domain. Unexpectedly, an inactivating mutation to the NES of chromosomal wis1(+) does not affect the subcellular localization of Spc1 MAPK, whereas this NES mutation disturbs the cytoplasmic localization of Wis1. However, when Wis1 is targeted to the nucleus by fusing to a nuclear localization signal sequence, stress-induced nuclear translocation of Spc1 is abrogated, indicating that cytoplasmic Wis1 is required for nuclear transport of Spc1 upon stress. Moreover, we have observed that a fraction of Wis1 translocates into the nucleus in response to stress. These results suggest that cytoplasmic localization of Wis1 MAPKK by its NES is important for stress signaling to the nucleus.

p38 MAPK inhibition enhances PS-341 (bortezomib)-induced cytotoxicity against multiple myeloma cells.

Although PS-341 (bortezomib) is a promising agent to improve multiple myeloma (MM) patient outcome, 65% of patients with relapsed and refractory disease do not respond. We have previously shown that heat shock protein (Hsp)27 is upregulated after PS-341 treatment, that overexpression of Hsp27 confers PS-341 resistance, and that inhibition of Hsp27 overcomes PS-341 resistance. Since Hsp27 is a downstream target of p38 mitogen-activated protein kinase (MAPK)/MAPK-mitogen-activated protein kinase-2 (MAPKAPK2), we hypothesized that inhibition of p38 MAPK activity could augment PS-341 cytotoxicity by downregulating Hsp27. Although p38 MAPK inhibitor SCIO-469 (Scios Inc, CA, USA) alone did not induce significant growth inhibition, it blocked baseline and PS-341-triggered phosphorylation of p38 MAPK as well as upregulation of Hsp27, associated with enhanced cytotoxicity in MM.1S cells. Importantly, SCIO-469 enhanced phosphorylation of c-Jun NH2-terminal kinase (JNK) and augmented cleavage of caspase-8 and poly(ADP)-ribose polymerase. Moreover, SCIO-469 downregulated PS-341-induced increases in G2/M-phase cells, associated with downregulation of p21Cip1 expression. Importantly, SCIO-469 treatment augmented cytotoxicity of PS-341 even against PS-341-resistant cell lines and patient MM cells. These studies therefore provide the framework for clinical trials of SCIO-469 to enhance sensitivity and overcome resistance to PS-341, thereby improving patient outcome in MM.

Transforming growth factor beta receptor I kinase inhibitor down-regulates cytokine secretion and multiple myeloma cell growth in the bone marrow microenvironment.

PURPOSE: Transforming growth factors (TGFs) have pleiotropic biological effects on tumor cells and their environment. In multiple myeloma (MM), we have reported that bone marrow stromal cells (BMSCs) from MM patients produce more TGF-beta1 than BMSCs from healthy donors, which in turn induces interleukin (IL)-6 secretion. We show here that the TGF-beta receptor I kinase inhibitor SD-208 significantly decreases secretion of both IL-6 and vascular endothelial growth factor (VEGF) from BMSCs, as well as tumor cell growth triggered by MM cell adhesion to BMSCs. EXPERIMENTAL DESIGN: Cytokine production and MM cell proliferation triggered by TGF-beta1 or adhesion to BMSCs were examined in the presence or absence of SD-208. Effects of SD-208 on TGF-beta1-induced signaling pathways triggering IL-6 and VEGF transcription in BMSCs were also delineated. RESULTS: SD-208 significantly inhibits not only transcription but also secretion of both IL-6 and VEGF from BMSCs triggered by either TGF-beta1 or adhesion of MM cells to BMSCs. Moreover, SD-208 decreased tumor cell growth triggered by MM cell adhesion to BMSCs. SD-208 works, at least in part, by blocking TGF-beta1-triggered nuclear accumulation of Smad2/3 and hypoxia-inducible factor 1alpha, as well as related production of IL-6 and VEGF, respectively. CONCLUSIONS: These studies indicate that SD-208 inhibits production of cytokines mediating MM cell growth, survival, drug resistance, and migration in the BM milieu, thereby providing the preclinical rationale for clinical evaluation of SD-208 to improve patient outcome in MM.

Azacitidine and decitabine have different mechanisms of action in non-small cell lung cancer cell lines.

Azacitidine (AZA) and decitabine (DAC) are cytidine azanucleoside analogs with clinical activity in myelodysplastic syndromes (MDS) and potential activity in solid tumors. To better understand the mechanism of action of these drugs, we examined the effects of AZA and DAC in a panel of non-small cell lung cancer (NSCLC) cell lines. Of 5 NSCLC lines tested in a cell viability assay, all were sensitive to AZA (EC50 of 1.8-10.5 µM), while only H1299 cells were equally sensitive to DAC (EC50 of 5.1 µM). In the relatively DAC-insensitive cell line A549, both AZA and DAC caused DNA methyltransferase I depletion and DNA hypomethylation; however, only AZA significantly induced markers of DNA damage and apoptosis, suggesting that mechanisms in addition to, or other than, DNA hypomethylation are important for AZA-induced cell death. Cell cycle analysis indicated that AZA induced an accumulation of cells in sub-G1 phase, whereas DAC mainly caused an increase of cells in G2/M. Gene expression analysis of AZA- and DAC-treated cells revealed strikingly different profiles, with many genes distinctly regulated by each drug. In summary, while both AZA and DAC caused DNA hypomethylation, distinct effects were demonstrated on regulation of gene expression, cell cycle, DNA damage, and apoptosis.

A comparison of azacitidine and decitabine activities in acute myeloid leukemia cell lines.

BACKGROUND: The cytidine nucleoside analogs azacitidine (AZA) and decitabine (DAC) are used for the treatment of patients with myelodysplastic syndromes and acute myeloid leukemia (AML). Few non-clinical studies have directly compared the mechanisms of action of these agents in a head-to-head fashion, and the agents are often viewed as mechanistically similar DNA hypomethylating agents. To better understand the similarities and differences in mechanisms of these drugs, we compared their in vitro effects on several end points in human AML cell lines. METHODOLOGY/PRINCIPAL FINDINGS: Both drugs effected DNA methyltransferase 1 depletion, DNA hypomethylation, and DNA damage induction, with DAC showing equivalent activity at concentrations 2- to 10-fold lower than AZA. At concentrations above 1 microM, AZA had a greater effect than DAC on reducing cell viability. Both drugs increased the sub-G1 fraction and apoptosis markers, with AZA decreasing all cell cycle phases and DAC causing an increase in G2-M. Total protein synthesis was reduced only by AZA, and drug-modulated gene expression profiles were largely non-overlapping. CONCLUSIONS/SIGNIFICANCE: These data demonstrate shared mechanisms of action of AZA and DAC on DNA-mediated markers of activity, but distinctly different effects in their actions on cell viability, protein synthesis, cell cycle, and gene expression. The differential effects of AZA may be mediated by RNA incorporation, as the distribution of AZA in nucleic acid of KG-1a cells was 65:35, RNA:DNA.

Inhibition of p38alpha MAPK disrupts the pathological loop of proinflammatory factor production in the myelodysplastic syndrome bone marrow microenvironment.

Myelodysplastic syndromes (MDS) are common causes of ineffective hematopoiesis and cytopenias in the elderly. Various myelosuppressive and proinflammatory cytokines have been implicated in the high rates of apoptosis and hematopoietic suppression seen in MDS. We have previously shown that p38 MAPK is overactivated in MDS hematopoietic progenitors, which led to current clinical studies of the selective p38alpha inhibitor, SCIO-469, in this disease. We now demonstrate that the myelosuppressive cytokines TNFalpha and IL-1beta are secreted by bone marrow (BM) cells in a p38 MAPK-dependent manner. Their secretion is stimulated by paracrine interactions between BM stromal and mononuclear cells and cytokine induction correlates with CD34+ stem cell apoptosis in an inflammation-simulated in vitro bone marrow microenvironment. Treatment with SCIO-469 inhibits TNF secretion in primary MDS bone marrow cells and protects cytogenetically normal progenitors from apoptosis ex vivo. Furthermore, p38 inhibition diminishes the expression of TNFalpha or IL-1beta-induced proinflammatory chemokines in BM stromal cells. These data indicate that p38 inhibition has anti-inflammatory effects on the bone marrow microenvironment that complements its cytoprotective effect on progenitor survival. These findings support clinical investigation of p38alpha as a potential therapeutic target in MDS and other related diseases characterised by inflammatory bone marrow failure.

Inhibition of overactivated p38 MAPK can restore hematopoiesis in myelodysplastic syndrome progenitors.

The myelodysplastic syndromes (MDSs) are collections of heterogeneous hematologic diseases characterized by refractory cytopenias as a result of ineffective hematopoiesis. Development of effective treatments has been impeded by limited insights into any unifying pathogenic pathways. We provide evidence that the p38 MAP kinase is constitutively activated or phosphorylated in MDS bone marrows. Such activation is uniformly observed in varied morphologic subtypes of low-risk MDS and correlates with enhanced apoptosis observed in MDS hematopoietic progenitors. Most importantly, pharmacologic inhibition of p38alpha by a novel small molecule inhibitor, SCIO-469, decreases apoptosis in MDS CD34+ progenitors and leads to dose-dependant increases in erythroid and myeloid colony formation. Down-regulation of the dominant p38alpha isoform by siRNA also leads to enhancement of hematopoiesis in MDS bone marrow progenitors in vitro. These data implicate p38 MAPK in the pathobiology of ineffective hematopoiesis in lowrisk MDS and provide a strong rationale for clinical investigation of SCIO-469 in MDS.