Lenalidomide inhibits the malignant clone and up-regulates theSPARCgene mapping to the commonly deleted region in 5q− syndrome patients

Abstract

Myelodysplastic syndromes (MDSs) are a group of hematopoietic stem cell disorders characterized by ineffective hematopoiesis and peripheral blood cytopenias. Lenalidomide has dramatic therapeutic effects in patients with low-risk MDS and a chromosome 5q31 deletion, resulting in complete cytogenetic remission in >60% of patients. The molecular basis of this remarkable drug response is unknown. To gain insight into the molecular targets of lenalidomide we investigated its in vitro effects on growth, maturation, and global gene expression in isolated erythroblast cultures from MDS patients with del(5)(q31). Lenalidomide inhibited growth of differentiating del(5q) erythroblasts but did not affect cytogenetically normal cells. Moreover, lenalidomide significantly influenced the pattern of gene expression in del(5q) intermediate erythroblasts, with the VSIG4, PPIC, TPBG, activin A, and SPARC genes up-regulated by >2-fold in all samples and many genes involved in erythropoiesis, including HBA2, GYPA, and KLF1, down-regulated in most samples. Activin A, one of the most significant differentially expressed genes between lenalidomide-treated cells from MDS patients and healthy controls, has pleiotropic functions, including apoptosis of hematopoietic cells. Up-regulation and increased protein expression of the tumor suppressor gene SPARC is of particular interest because it is antiproliferative, antiadhesive, and antiangiogenic and is located at 5q31-q32, within the commonly deleted region in MDS 5q؊ syndrome. We conclude that lenalidomide inhibits growth of del(5q) erythroid progenitors and that the up-regulation of SPARC and activin A may underlie the potent effects of lenalidomide in MDS with del(5)(q31). SPARC may play a role in the pathogenesis of the 5q؊ syndrome.gene expression profiling ͉ myelodysplastic syndromes ͉ microarray ͉ erythropoiesis ͉ osteonectin

Recurrent genetic defects on chromosome 7q in myeloid neoplasms

“…Several other hematopoiesis-related genes and tumor suppressor genes are located in the CDR (e.g., CTNNA1, PPP2CA, EGR1, SPARC, RPS14 and CDC25C) with previously reported [14,[27][28][29][30][31], however, we were unable to detect hemi-or heterozygous mutations in Oncotarget 6491 www.impactjournals.com/oncotarget these genes. It is possible that they contribute to clinical heterogeneity, shape the clinical phenotype or modulate the growth advantage of the del(5q).…”

Effects of L-leucine in 5q- syndrome and other RPS14-deficient erythroblasts

“…Cells were cultured according to a method developed to study the generation of erythroblasts 7 and evaluated at day 14 of culture. RPS14 expression levels were significantly decreased by approximately 50% in cells expressing RPS14 shRNAs (Figure 1a).…”

“…Analysis of RPS14-deficient cells from healthy controls. Cells were cultured according to a method developed to study the generation of erythroblasts 7 and evaluated at day 14 of culture. CD34 þ cells were cultured for 14 days as described 7 and on day 7, erythropoietin (Roche, Basel, Switzerland) at 2 U/ml was added to the medium.…”

“…Cells were cultured according to a method developed to study the generation of erythroblasts 7 and evaluated at day 14 of culture. CD34 þ cells were cultured for 14 days as described 7 and on day 7, erythropoietin (Roche, Basel, Switzerland) at 2 U/ml was added to the medium. shRNA sequences targeting RPS14 and cloned into a pLKO.1 vector were obtained from Sigma Aldrich (Gillingham, UK) (TRCN0000008641 and TRCN0000008644, henceforth termed sh41 and sh44, respectively).…”

Clonal evolution in myelodysplastic syndromes with isolated del(5q): the importance of genetic monitoring

“…Other genes on chromosome arm 5q have also been implicated in the pathogenesis of del(5q) MDS, including the tumor suppressor gene SPARC located within the commonly deleted region, 8 and others that are located outside the band 5q32-33 commonly deleted region associated with MDS, including EGR1, CTNNA1, APC and NPM1 ( Figure 1B) . [9][10][11] Altered bone marrow microenvironment and the effects of lenalidomide Evidence suggests that there may be a bone marrow stromal defect in MDS with del(5q), resulting in impaired ability to support growth of normal hematopoietic progenitors.…”