31 DEREGULATION OF PI3K/AKT SIGNALING AND WNT TARGET GENES IN BONE MARROW MESENCHYMAL STROMAL CELLS FROM PATIENTS WITH MDS

Bone marrow mesenchymal stem cells (BM-MSCs) exhibit multiple abnormalities in myelodysplastic syndromes (MDS), including impaired proliferative and clonogenic capacity, altered morphology, increased senescence, impaired immunoregulatory properties, and reduced hematopoietic support capacity. Common signaling pathways, such as PI3K/AKT and WNT/β-catenin, regulate multiple MSC properties, including proliferation, differentiation, and cell–cell interaction. Here, with polymerase chain reaction arrays, we investigated the expression of 84 genes belonging to the PI3K/AKT signaling pathways in BM-MSCs isolated from patients with MDS, acute myeloid leukemia, and therapy-related myeloid neoplasms, using as a control BM-MSCs isolated from patients with untreated early-stage lymphomas without BM involvement. Statistically significant downregulation of GSK3β, SOS1, RASA1, and MTCP1 gene expression was observed in BM-MSCs isolated from patients with de novo MDS, as compared with controls. Moreover, expression of the GSK3β protein was reduced in MDS-derived MSCs, and was associated with concomitant reduction of phosphorylation at Ser-9. The role of GSK3β in the downstream WNT/β-catenin signaling pathway was assessed. We investigated β-catenin protein levels and expression of 84 genes belonging to the WNT target gene pathway using PCR arrays in MDS BM-MSCs, as compared with control BM-MSCs. GSK3β impairment translated into decreased β-catenin protein levels and downregulation of several WNT/β-catenin target genes (SOX9, EGR1, WISP1). These findings suggest that deregulation of genes involved in the PI3K/AKT and WNT signaling pathways may contribute to the phenotypical abnormalities of MDS BM-MSCs.