El perfil transcriptómico de la célula tumoral circulante (CTD) del mieloma múltiple: un nuevo modelo para comprender la diseminación de la enfermedad

CO-010 Introducción: El número de células tumorales circulantes (CTCs) predice el riesgo de transformación en mieloma múltiple (MM) asintomático, así como la supervivencia en MM activo. Datos recientes sugieren que, conforme el tumor progresa y el microambiente se vuelve más hipóxico, las células plasmáticas (CP) clonales pasan a la circulación sistémica favoreciendo la constante invasión de nuevas regiones en la médula ósea (MO). Habría que señalar que la frecuencia de las CTCs es típicamente baja, por lo que sería concebible que dicha diseminación del MM dependiera de unas pocas células con unas características únicas que inducirían su salida de la médula y la extensión de la enfermedad a través de la sangre periférica (SP). Esta hipótesis no ha sido demostrada hasta ahora debido a que el perfil transcriptómico de la CTC en el MM no ha sido investigado. Objetivos: Determinar funciones moleculares específicas en las CTCs que permitan identificar eventos responsables de la diseminación del MM a través del flujo sanguíneo. ..

LBH589, a deacetylase inhibitor, induces apoptosis in adult T-cell leukemia/lymphoma cells via activation of a novel RAIDD-caspase-2 pathway

Adult T-cell leukemia/lymphoma (ATLL), an aggressive neoplasm etiologically associated with human T-lymphotropic virus type-1 (HTLV-1), is resistant to treatment. In this study, we examined the effects of a new inhibitor of deacetylase enzymes, LBH589, on ATLL cells. LBH589 effectively induced apoptosis in ATLL-related cell lines and primary ATLL cells and reduced the size of tumors inoculated in SCID mice. Analyses, including with a DNA microarray, revealed that neither death receptors nor p53 pathways contributed to the apoptosis. Instead, LBH589 activated an intrinsic pathway through the activation of caspase-2. Furthermore, small interfering RNA experiments targeting caspase-2, caspase-9, RAIDD, p53-induced protein with a death domain (PIDD) and RIPK1 (RIP) indicated that activation of RAIDD is crucial and an event initiating this pathway. In addition, LBH589 caused a marked decrease in levels of factors involved in ATLL cell proliferation and invasion such as CCR4, IL-2R and HTLV-1 HBZ-SI, a spliced form of the HTLV-1 basic zipper factor HBZ. In conclusion, we showed that LBH589 is a strong inducer of apoptosis in ATLL cells and uncovered a novel apoptotic pathway initiated by activation of RAIDD

Valproic acid inhibits adhesion of vincristine- and cisplatin-resistant neuroblastoma tumour cells to endothelium

Drug resistance to chemotherapy is often associated with increased malignancy in neuroblastoma (NB). In pursuit of alternative treatments for chemoresistant tumour cells, we tested the response of multidrug-resistant SKNSH and of vincristine (VCR)-, doxorubicin (DOX)-, or cisplatin (CDDP)-resistant UKF-NB-2, UKF-NB-3 or UKF-NB-6 NB tumour cell lines to valproic acid (VPA), a differentiation inducer currently in clinical trials. Drug resistance caused elevated NB adhesion (UKF-NB-2VCR, UKF-NB-2DOX, UKF-NB-2CDDP, UKF-NB-3VCR, UKF-NB-3CDDP, UKF-NB-6VCR, UKF-NB-6CDDP) to an endothelial cell monolayer, accompanied by downregulation of the adhesion receptor neural cell adhesion molecule (NCAM). Based on the UKF-NB-3 model, N-myc proteins were enhanced in UKF-NB-3VCR and UKF-NB-3CDDP, compared to the drug naïve controls. p73 was diminished, whereas the p73 isoform deltaNp73 was upregulated in UKF-NB-3VCR and UKF-NB-3CDDP. Valproic acid blocked adhesion of UKF-NB-3VCR and UKF-NB-3CDDP, but not of UKF-NB-3DOX, and induced the upregulation of NCAM surface expression, NCAM protein content and NCAM coding mRNA. Valproic acid diminished N-myc and enhanced p73 protein level, coupled with downregulation of deltaNp73 in UKF-NB-3VCR and UKF-NB-3CDDP. Valproic acid also reverted enhanced adhesion properties of drug-resistant UKF-NB-2, UKF-NB-6 and SKNSH cells, and therefore may provide an alternative approach to the treatment of drug-resistant NB by blocking invasive processes

The DAC system and associations with multiple myeloma

Despite the clear progress achieved in recent years in the treatment of MM, most patients eventually relapse and therefore novel therapeutic options are still necessary for these patients. In this regard, several drugs that target specific mechanisms of the tumor cells are currently being explored in the preclinical and clinical setting. This manuscripts offers a review of the rationale and current status of the antimyeloma activity of one of the most relevant examples of these targeted drugs: deacetylase inhibitors (DACi). Several studies have demonstrated the prooncogenic activity of deacetylases (DACs) through the targeting not only of histones but also of non histone proteins relevant to tumor progression, such as p53, E2F family members, Bcl-6, Hsp90, HIF-1α or Nur77. This fact together with the DACs overexpression present in several tumors, has prompted the development of some DACi with potential antitumor effect. This situation is also evident in the case of MM as two mechanisms of DACi, the inhibition of the epigenetic inactivation of p53 and the blockade of the unfolded protein response, through the inhibition of the aggressome formation (by targeting DAC6) and the inactivation of the chaperone system (by acetylating HSP-90), provides the rationale for the exploration of the potential antimyeloma activity of these compounds. Several DACi with different chemical structure and different selectivity for targeting the DAC families have been tested in MM. Their preclinical activity in monotherapy has been quite exciting and has been described to be mediated by various mechanisms: the induction of apoptosis and cell cycle arrest mainly by the upregulation of p21; the interferece with the interaction between plasma cells and the microenvironment, by reducing the expression and signalling of several cytokines or by inhibiting angiogenesis. Finally they also have a role in protecting murine models from myeloma bone disease. Neverteless, the clinical activity in monotherapy of these drugs in relapsed/refractory MM patients has been very modest. This has prompted the development of combinations such as the one with bortezomib or lenalidomide and dexamethasone, which have already been taken into the clinics with positive preliminary results

The DAC system and associations with acute leukemias and myelodysplastic syndromes

Imbalances of histone acetyltransferase (HAT) and deacetylase activity (DAC) that result in deregulated gene expression are commonly observed in leukemias. These alterations provide the basis for novel therapeutic approaches that target the epigenetic mechanisms implicated in leukemogenesis. As the acetylation status of histones has been linked to transcriptional regulation of genes involved particularly in differentiation and apoptosis, DAC inhibitors (DACi) have attracted considerable attention for treatment of hematologic malignancies. DACi encompass a structurally diverse family of compounds that are being explored as single agents as well as in combination with chemotherapeutic drugs, small molecule inhibitors of signaling pathways and hypomethylating agents. While DACi have shown clear evidence of activity in acute myeloid leukemia, myelodysplastic syndromes and lymphoid malignancies, their precise role in treatment of these different entities remain to be elucidated. Successful development of these compounds as elements of novel targeted treatment strategies for leukemia will require that clinical studies be performed in conjunction with translational research including efforts to identify predictive biomarkers

Polycomb Target Genes Are Silenced in Multiple Myeloma

Multiple myeloma (MM) is a genetically heterogeneous disease, which to date remains fatal. Finding a common mechanism for initiation and progression of MM continues to be challenging. By means of integrative genomics, we identified an underexpressed gene signature in MM patient cells compared to normal counterpart plasma cells. This profile was enriched for previously defined H3K27-tri-methylated genes, targets of the Polycomb group (PcG) proteins in human embryonic fibroblasts. Additionally, the silenced gene signature was more pronounced in ISS stage III MM compared to stage I and II. Using chromatin immunoprecipitation (ChIP) assay on purified CD138+ cells from four MM patients and on two MM cell lines, we found enrichment of H3K27me3 at genes selected from the profile. As the data implied that the Polycomb-targeted gene profile would be highly relevant for pharmacological treatment of MM, we used two compounds to chemically revert the H3K27-tri-methylation mediated gene silencing. The S-adenosylhomocysteine hydrolase inhibitor 3-Deazaneplanocin (DZNep) and the histone deacetylase inhibitor LBH589 (Panobinostat), reactivated the expression of genes repressed by H3K27me3, depleted cells from the PRC2 component EZH2 and induced apoptosis in human MM cell lines. In the immunocompetent 5T33MM in vivo model for MM, treatment with LBH589 resulted in gene upregulation, reduced tumor load and increased overall survival. Taken together, our results reveal a common gene signature in MM, mediated by gene silencing via the Polycomb repressor complex. The importance of the underexpressed gene profile in MM tumor initiation and progression should be subjected to further studies

Targeting the IGF-1R signaling and mechanisms for epigenetic gene silencing in human multiple myeloma

Multiple myeloma (MM) is a B cell malignancy characterized by the expansion of clonal plasmablast/plasma cells within the bone-marrow. It is well established that the bone-marrow microenvironment has a pivotal role in providing critical cytokines and cell–cell interactions to support the growth and survival of the MM tumor clone. The pathogenesis of MM is, however, only fragmentarily understood. Detailed genomic analysis reveals a heterogeneous and complex pattern of structural and numerical chromosomal aberrations. In this review we will discuss some of the recent results on the functional role and potential clinical use of the IGF-1R, one of the major mediators of growth and survival for MM. We will also describe some of our results on epigenetic gene silencing in MM, as it may indeed constitute a novel basis for the understanding of tumor initiation and maintenance in MM and thus may change the current view on treatment strategies for MM

Dasatinib as a Bone-Modifying Agent: Anabolic and Anti-Resorptive Effects

This is an open-access article distributed under the terms of the Creative Commons Attribution License.-- et al.[Background]: Bone loss, in malignant or non-malignant diseases, is caused by increased osteoclast resorption and/or reduced osteoblast bone formation, and is commonly associated with skeletal complications. Thus, there is a need to identify new agents capable of influencing bone remodeling. We aimed to further pre-clinically evaluate the effects of dasatinib (BMS-354825), a multitargeted tyrosine kinase inhibitor, on osteoblast and osteoclast differentiation and function. [Methods]: For studies on osteoblasts, primary human bone marrow mensenchymal stem cells (hMSCs) together with the hMSC-TERT and the MG-63 cell lines were employed. Osteoclasts were generated from peripheral blood mononuclear cells (PBMC) of healthy volunteers. Skeletally-immature CD1 mice were used in the in vivo model. [Results]: Dasatinib inhibited the platelet derived growth factor receptor-β (PDGFR-β), c-Src and c-Kit phosphorylation in hMSC-TERT and MG-63 cell lines, which was associated with decreased cell proliferation and activation of canonical Wnt signaling. Treatment of MSCs from healthy donors, but also from multiple myeloma patients with low doses of dasatinib (2-5 nM), promoted its osteogenic differentiation and matrix mineralization. The bone anabolic effect of dasatinib was also observed in vivo by targeting endogenous osteoprogenitors, as assessed by elevated serum levels of bone formation markers, and increased trabecular microarchitecture and number of osteoblast-like cells. By in vitro exposure of hemopoietic progenitors to a similar range of dasatinib concentrations (1-2 nM), novel biological sequelae relative to inhibition of osteoclast formation and resorptive function were identified, including F-actin ring disruption, reduced levels of c-Fos and of nuclear factor of activated T cells 1 (NFATc1) in the nucleus, together with lowered cathepsin K, αVβ3 integrin and CCR1 expression. [Conclusions]: Low dasatinib concentrations show convergent bone anabolic and reduced bone resorption effects, which suggests its potential use for the treatment of bone diseases such as osteoporosis, osteolytic bone metastasis and myeloma bone disease. © 2012 Garcia-Gomez et al.This work was supported by grants from the Spanish Ministry of Science and Innovation – ISCIII (PI081825); Mutua Madrileña Medical Research Foundation (AP27262008); Centro en Red of Regenerative Medicine and Cellular Therapy from Castilla y León, Consejería de Sanidad JCyL – ISCIII; the Cooperative Research Thematic Network in Cancer (RTICC; RD06/0020/0006 and RD03/0020/0041); and Spanish FIS (PS09/01897). AG-G and CS are supported by the Centro en Red of Regenerative Medicine and Cellular Therapy from Castilla y León Project.Peer Reviewe

Histone deacetylase inhibitors: potential targets responsible for their anti-cancer effect

The histone deacetylase inhibitors (HDACi) have demonstrated anticancer efficacy across a range of malignancies, most impressively in the hematological cancers. It is uncertain whether this clinical efficacy is attributable predominantly to their ability to induce apoptosis and differentiation in the cancer cell, or to their ability to prime the cell to other pro-death stimuli such as those from the immune system. HDACi-induced apoptosis occurs through altered expression of genes encoding proteins in both intrinsic and extrinsic apoptotic pathways; through effects on the proteasome/aggresome systems; through the production of reactive oxygen species, possibly by directly inducing DNA damage; and through alterations in the tumor microenvironment. In addition HDACi increase the immunogenicity of tumor cells and modulate cytokine signaling and potentially T-cell polarization in ways that may contribute the anti-cancer effect in vivo. Here, we provide an overview of current thinking on the mechanisms of HDACi activity, with attention given to the hematological malignancies as well as scientific observations arising from the clinical trials. We also focus on the immune effects of these agents