Impaired expression of DICER, DROSHA, SBDS and some microRNAs in mesenchymal stromal cells from myelodysplastic syndrome patients

Abstract

The online version of this article has a Supplementary Appendix. BackgroundRecent findings suggest that a specific deletion of Dicer1 in mesenchymal stromal cell-derived osteoprogenitors triggers several features of myelodysplastic syndrome in a murine model. Our aim was to analyze DICER1 and DROSHA gene and protein expression in mesenchymal stromal cells (the osteoblastic progenitors) obtained from bone marrow of myelodysplastic syndrome patients, in addition to microRNA expression profile and other target genes such as SBDS, a DICER1-related gene that promotes bone marrow dysfunction and myelodysplasia when repressed in a murine model. Design and MethodsMesenchymal stromal cells from 33 bone marrow samples were evaluated. DICER, DROSHA and SBDS gene expression levels were assessed by real-time PCR and protein expression by Western blot. MicroRNA expresion profile was analyzed by commercial low-density arrays and some of these results were confirmed by individual real-time PCR. ResultsMesenchymal stromal cells from myelodysplastic syndrome patients showed lower DICER1 (0.65±0.08 vs. 1.91±0.57; P=0.011) and DROSHA (0.62±0.06 vs. 1.38±0.29; P=0.009) gene expression levels, two relevant endonucleases associated to microRNA biogenesis, in comparison to normal myelodysplastic syndrome. These findings were confirmed at protein levels by Western blot. Strikingly, no differences were observed between paired mononuclear cells from myelodysplastic syndrome and controls. In addition, mesenchymal stromal cells from myelodysplastic syndrome patients showed significant lower SBDS (0.63±0.06 vs. 1.15±0.28; P=0.021) gene expression levels than mesenchymal stromal cells from healthy controls. Furthermore, mesenchymal stromal cells from myelodysplastic syndrome patients showed an underlying microRNA repression compared to healthy controls. Real-time PCR approach confirmed that mir-155, miR-181a and miR-222 were down-expressed in mesenchymal stromal cells from myelodysplastic syndrome patients. ConclusionsThis is the first description of an impaired microRNA biogenesis in human mesenchymal stromal cells from myelodysplastic syndrome patients, where DICER1 and DROSHA gene and protein downregulation correlated to a gene and microRNA abnormal expression profile, validating the animal model results previously described.Key words: mesenchymal stem cells, DICER, DROSHA, myelodysplastic syndrome.Citation: Santamaría C, Muntión S, Rosón B, Blanco B, López-Villar O, Carrancio S, Sánchez-Guijo FM, Díez-Campelo M, Alvarez-Fernández S, Sarasquete ME, de las Rivas J, González M, San Miguel JF, and del Cañizo MC. Impaired expression of DICER, DROSHA, SBDS and some microRNAs in mesenchymal stromal cells from myelodysplastic syndrome patients. Haematologica 2012;97(8):1218-1224. doi:10.3324/haematol.2011 This is an open-access paper. ABSTRACT© F e r r a t a S t o r t i F o u n d a t i o n

Down-regulation of Dicer1 promotes cellular senescence and decreases the differentiation and stem cell-supporting capacities of mesenchymal stromal cells in patients with myelodysplastic syndrome

“…24 We found that miR-93 and miR-20a expression levels were significantly reduced in MDS-MSC. What is more, overexpression of miR-93/miR-20a reversed cellular senescence in MDS-MSC by targeting p21.…”

“…[18][19][20] The ablation of Dicer1 (an RNAse III endonuclease essential for miRNA biogenesis) and the loss of mature miRNA in embryonic fibroblasts and endothelial cells inhibited cell proliferation and induced a premature senescence phenotype. 21,22 Although recent striking findings indicate that Dicer1 deletion can induce an MDS phenotype in mice 23 and that Dicer1 expression is reduced in MSC from MDS patients, 24 the precise mechanism by which the Dicer1 gene contributes to the pathogenesis of MDS remains elusive. We inferred that disordered expression of Dicer1 could contribute to abnormal MSC senescence and impaired stromal support in MDS.…”

Extracellular vesicle miR-7977 is involved in hematopoietic dysfunction of mesenchymal stromal cells via poly(rC) binding protein 1 reduction in myeloid neoplasms

“…Consistent with these notions, it was previously reported that chromosomal abnormalities such as loss of heterozygosity and uniparental disomy (UPD), which can result from doublestranded breaks, are sometimes observed in MSCs derived from AML/MDS patients. [39][40][41] Another possible explanation is that certain factors can directly induce functional abnormality in MSCs. Recently, it was demonstrated that the transplantation of chronic myelogenous leukemia (CML) repopulating cells into immunodeficient mice altered the microenvironmental regulation of the stem cell niche.…”

Myeloid malignancies and the microenvironment

“…Loss of DICER1 in osteoprogenitor cells (but not in mature osteoblasts) resulted in downregulation of the ribosome maturation protein SBDS, which is mutated in human Shwachman-Bodian-Diamond syndrome and is associated with congenital BM failure and leukemic predisposition. 76 Reduced expression of DICER, DROSHA, and SBDS has been noted in BMSCs from patients with MDS, 77 emphasizing the potential clinical relevance of these findings. A recent study has provided mechanistic insight on genotoxic stress caused by mutations in BMSCs, which can impair normal hematopoiesis and favor leukemogenesis.…”