Gene Expression Changes In Patients with 5q- Syndrome Treated with Lenalidomide

The 5q- syndrome constitutes a World Health Organization (WHO)-defined category of myelodysplastic syndromes (MDS) with the following hematological features: macrocytic anemia, erythroid hypoplasia, normal or elevated platelet count, hypolobulated megakaryocytes and isolated del(5q). Its pathogenesis remains uncertain. Lenalidomide has shown impressive rate of erythroid and in some cases even cytogenetic response. Lenalidomide is anti-angiogenic, anti-adhesive, affects important cytokine circuits and can directly induce growth arrest and apoptosis in certain types of malignant cells. There is also a potent immunomodulatory effect including costimulation of CD4⁺ and CD8⁺ T-cells that are partially activated via the T-cell receptor and enhancement of NK cell-mediated lysis. The mechanism of lenalidomide on 5q- syndromes patients is not known, but appears to be suppression of the 5q- clone, resulting in transfusion-independence and a rise in hemoglobin levels. The aim of this study is to investigate the direct effects of lenalidomide on gene expression in isolated CD3+ T-lymphocytes and CD14+ monocytes from 5q- syndromes.

Six lenalidomide responding patients (three females and three males) with 5q- syndromes (aged 55 to 75 years) and six healthy controls (aged 32 to 74 years) were included in the study. Samples of peripheral blood were collected before the treatment and then at the time of first erytroid response (2-5 months). HumanRef-8 v2 Expression Bead Chips (Illumina) were used to generate expression profiles. The raw data were normalized with the R software, lumi package. Normalized data were filtered by detection p-value <0.01. Differentially expressed genes were identified by Significance Analysis of Microarrays (SAM).

558/228 significantly differentially expressed genes between CD14+ monocytes/CD3+ T-lymfocytes patients and control samples were identified (fold change >1.5; p<0.05) before the treatment. This gene list was imported into the DAVID gene ontology and identified 4 significantly affected pathways (p<0.05): Systemic lupus erythematosus (11 genes), NOD-like receptor signaling pathway (8 genes), Cell cycle (9 genes), Pathogenic coli infection (7 genes). Among the most up-regulated genes in monocytes were: globin genes (HBA, HBB, HBG and HBG2), IL8, CDKN1A, TNF, TNFAIP3, BHLHB2, CXCL2, and CD83 genes. In T lymphocytes we have found in addition up-regulation of JUN, FOS and ALAS2. Genes significantly differentially expressed between lenalidomide-treated patient and baseline treatment in CD14+ monocytes was found in 267 genes. Out of these, 90 genes showed down-regulation, while the rest of the genes were up-regulated in patient samples. Using this set of genes into the DAVID gene ontology application, the gene annotation found the following biological processes: Regulation of protein kinase cascade (12 genes), regulation of I-kappaB kinase/NF-kappaB cascade (8 genes), regulation of lymphocyte mediated immunity (4 genes) and negative regulation of apoptosis (12 genes). The following pathways (p<0.05) that contained genes significantly deregulated in patients responding to lenalidomide were: Fc gamma R-mediated phagocytosis, Leukocyte transendothelial migration and Lysosome pathway. The most down-regulated genes by lenalidomide in monocytes were TNF, STAB1, IL1B, MYB, FYN and NFKB2. The most significantly up-regulated genes by lenalidomide in monocytes were NCF1, EEF1G, RPS28, RN28S1, RN28S1 and ARPC1B. No significantly differentially expressed genes were founded in T-lymfocytes before treatment and at the time of response. We observed large variability among patients.

Our results indicate that lenalidomide with a still unknown exact effect in 5q- causes significant changes in expression profile in many genes that are probably important in the pathogenesis of the disease and the treatment response. Significant decrease in relation to lenalidomide treatment was observed of tumor necrosis factor, interleukin 1 and transcription factor MYB. We plan next to monitor changes in gene expression during the course of therapy and comparing the gene expression in CD34⁺ cells before and after lenalidomide therapy. Supported by Celgene Corporation and grants NS/9634 MZCR, MZ0 UHKT2005 and MSM0021620808.

No relevant conflicts of interest to declare.