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Identification of p38 beta as a therapeutic target for the treatment of Sézary Syndrome

ABSTRACT: Cutaneous T-Cell Lymphomas (CTCL) represent a group of hematopoietic malignancies that home to the skin and have no known molecular basis for disease pathogenesis. Sézary syndrome (SS) is the leukemic variant of CTCL. Currently, CTCL is incurable, highlighting the need for new therapeutic modalities. We have previously observed that combined small-molecule inhibition of protein kinase C (PKC) β and glycogen synthase kinase 3 (GSK3) causes synergistic apoptosis in CTCL cell lines and patient cells. Through microarray analysis of a SS cell line, we surveyed global gene expression following combined PKCβ-GSK3 treatment to elucidate therapeutic targets responsible for cell death. Clinically relevant targets were defined as genes differentially expressed in SS patients that were modulated by combination-drug treatment of SS cells. Gene set enrichment analysis uncovered candidate genes enriched for an immune cell signature, specifically the T-cell receptor and MAPK signaling pathways. Further analysis identified p38 as a potential therapeutic target that is over-expressed in SS patients and decreased by synergistic-inhibitor treatment. This target was verified through small-molecule inhibition of p38 leading to cell death in both SS cell lines and patient cells. These data establish p38 as a new SS biomarker and potential therapeutic target for the treatment of CTCL.

ORGANISM(S): Homo sapiens

PROVIDER: GSE59179 | GEO | 2015/07/01

SECONDARY ACCESSION(S): PRJNA254540

REPOSITORIES: GEO

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Project description:Suberoyl Anilide Hydroxamic Acid (SAHA), also named under Vorinostat, is an inhibitor of class I and II histone deacetylases (HDACi) approved by the USA Food and Drug Administration (FDA) for the treatment of advanced and refractory cutaneous T-cell lymphomas (CTCL). Its limited efficacy led to its use in various combination therapies. Given that SAHA modifies the expression of many genes under control of Sp1 (or Sp3) transcription factors, we investigated here its association to the FDA-approved anticancer antibiotic Mithramycin (MitA), a direct inhibitor of the binding of Sp1 family factors to GC-rich DNA promoters. We found that MitA alone, similar to SAHA, efficiently induced the apoptotic death of peripheral blood lymphocytes from Sézary syndrome (SS) patients while the two drugs in combination demonstrated a synergistic effect that could even overcome the resistance to MitA used in mono-treatment. A deep analysis of gene expression profiling suggested that SAHA and MitA, either independently or synergistically, counteracted many intertwined pro-survival pathways mis-regulated in SS cells as TCR, Notch1, mTOR, PI3K/Akt, JAK/STAT and b-catenin pathways, as well as the resistance of these tumors to intrinsic and extrinsic apoptosis. This analysis also suggested that SAHA/MitA combined treatment might efficiently oppose to the abnormal adhesion, migration and invasive properties of SS cells, in addition their immunosuppressive behavior. Finally, from a mechanistic point of view, our observations strongly support a major role of additive or synergistic epigenetic modifications in the combined effect of the two drugs, with a rather limited contribution of Sp1 (or Sp3)-mediated transcriptional regulation. Peripheral blood tumor cells from Sézary patients were expanded in vitro and treated with SAHA and/or MitA previous to RNA isolation and Microarray processing. Deep analysis of gene expression profiling suggested that SAHA and Mithramycin A (MitA), either independently or synergistically, counteracted many interwined pro-survival pathways mis-regulated in Sézary cells, as well as abnormal adhesion, invasion and invasive properties. Data also favored additive or synergistic epigenetic modifications in the combined effect of the two drugs.

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Identification of p38 beta as a therapeutic target for the treatment of Sézary Syndrome

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