Abstract
Background: Essential thrombocythemia (ET) is a BCL-ABL1-negative myeloproliferative neoplasm characterized by increased number of mature megakaryocytes in the bone marrow and sustained thrombocytosis in the peripheral blood. ET is associated with an increased risk of hemorrhagic and thrombotic complications and leukemic transformation. In addition to somatic mutations, microRNA (miRNA) deregulation has been proposed to play roles in the molecular pathogenesis and disease phenotype in ET patients. The aims of this study were to investigate the plasma miRNA profiles in ET patients with those obtained from healthy adults (HA) and its correlation with clinical and prognostic features.
Methods: ET patients seen at the MacKay Memorial Hospital were enrolled into this study. The clinical and laboratory characteristics at the time of diagnosis or referral were determined retrospectively by chart review. Total plasma miRNA was derived from bone marrow or peripheral blood in patients or HA. Mutational status of JAK2V617F,CALR and MPL were detected by Sanger sequencing and/or allele-specific PCR. Plasma miRNA profiling was carried out on PanelChip™ Analysis System (Quark Biosciences, Taiwan) using a customized miRNA panel including 165 miRNAs called mirSCAN™ PanCancer Chips 1 & 2. KEGG pathways that miRNAs were associated with were analyzed using DIANA TOOLS - mirPath v.3. Differentially expressed miRNAs were identified by student t-test (P < 0.05) and significantly affected miRNAs in ET were identified by a change in expression of two-fold or more compared to the expression in HA. Statistical analysis was performed using SPSS.
Results: A total of 53 ET patients (median age at diagnosis 59 years; 60.4% females) were enrolled. Frequency of the 3 driver mutations was 64% for JAK2V617F, 15% CALR, 4% JAK2V617F and CALR co-mutations, and none for MPL. 17% of patients were classified as triple-negative. A total of 40 differentially expressed miRNAs were identified (Figure left axis) including 4 miRNAs (hsa-miR-940, hsa-miR-411-5p, hsa-miR-596 and hsa-miR-376c-3p) with higher expression levels. The putative target genes of these 40 differentially expressed miRNAs were enriched in signaling pathway including TGF-beta signaling pathway (p-value = 1.86E-12), Hippo signaling pathway (p-value = 1.84E-07), MAPK signaling pathway (p-value = 0.03), and FoxO signaling pathway (p-value < 0.001). According to the expression levels of these 40 miRNAs, samples were grouped into two clusters, i.e. low expression group and high expression group. ET patients with JAK2V617F were significantly associated with high expression of 40 miRNAs (n = 31 of 34, 91%) when compared with triple-negative ET patients (n = 5 of 9, 56%) (p = 0.03). ET patients with low expression of 40 miRNAs were significantly associated with acute leukemia transformation (n = 2 of 11, 18%) when compared with high expression group (n = 0 of 42, 0%) (p = 0.04). However, the expression levels of 40 miRNAs were not statistically correlated with other clinical features including hemogram, secondary solid cancer, myelofibrosis transformation, or thrombotic/hemorrhagic events.
Conclusions: In this cohort of ET patients, distinct plasma miRNA profiles correlated with JAK2V617F mutation and leukemic transformation. Larger cohort is warranted to validate our findings.
Chen:Quark Biosciences, Inc.: Employment. Kang:Quark Biosciences, Inc.: Employment. Huang:Quark Biosciences, Inc.: Employment. Lin:Quark Biosciences, Inc.: Employment. Wang:Quark Biosciences, Inc.: Employment.
