Microarray and Proteomic Analyses of Myeloproliferative Neoplasms with a Highlight on the mTOR Signaling Pathway

Abstract

The gene and protein expression profiles in myeloproliferative neoplasms (MPNs) may reveal gene and protein markers of a potential clinical relevance in diagnosis, treatment and prediction of response to therapy. Using cDNA microarray analysis of 25,100 unique genes, we studied the gene expression profile of CD34+ cells and granulocytes obtained from peripheral blood of subjects with essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (PMF). The microarray analyses of the CD34+ cells and granulocytes were performed from 20 de novo MPN subjects: JAK2 positive ET, PV, PMF subjects, and JAK2 negative ET/PMF subjects. The granulocytes for proteomic studies were pooled in 4 groups: PV with JAK2 mutant allele burden above 80%, ET with JAK2 mutation, PMF with JAK2 mutation and ET/PMF with no JAK2 mutation. The number of differentially regulated genes was about two fold larger in CD34+ cells compared to granulocytes. Thirty-six genes (including RUNX1, TNFRSF19) were persistently highly expressed, while 42 genes (including FOXD4, PDE4A) were underexpressed both in CD34+ cells and granulocytes. Using proteomic studies, significant up-regulation was observed for MAPK and PI3K/AKT signaling regulators that control myeloid cell apoptosis and proliferation: RAC2, MNDA, S100A8/9, CORO1A, and GNAI2. When the status of the mTOR signaling pathway related genes was analyzed, PI3K/AKT regulators were preferentially up-regulated in CD34+ cells of MPNs, with down-regulated major components of the protein complex EIF4F. Molecular profiling of CD34+ cells and granulocytes of MPN determined gene expression patterns beyond their recognized function in disease pathogenesis that included dominant up-regulation of PI3K/AKT signaling.

Phosphoproteomic Landscaping Identifies Non-canonical cKIT Signaling in Polycythemia Vera Erythroid Progenitors

“…PI-3K signaling was poorly active in JAK2 V617F-PV. Similar results were previously reported in blood mononuclear cells [by WB, (55)], neutrophils [by phosphoproteomic (56)] and CD34 + cells [by transcriptosome profiling (56)]. Therefore, it is not surprising that the survival of PV was not more sensitive than AB to inhibitors of mTOR/PI-3K, including rapamycin a derivative of which, Everolimus, is under clinical investigation in MPN (53, 55, 57), predicting that treatments with PI-3K inhibitors alone may have limited efficacy in PV.…”

Loss of Ezh2 cooperates with Jak2V617F in the development of myelofibrosis in a mouse model of myeloproliferative neoplasm

“…S100a8 and S100a9 are proinflammatory cytokine-like mediators that are found significantly upregulated in various human cancers including MF. [45][46][47] A recent report has shown that increased levels of S100a8 and S100a9 block erythroid differentiation in Rps14-haploinsufficient mouse model of MDS. 48 We observed erythroid differentiation defect and increased expression of S100a8 and S100a9 in Ezh2-deficient Jak2V617F (Jak2 VF/1 Ezh2 2/2 ) mice (Figures 2A and 6E).…”

Early and late stage MPN patients show distinct gene expression profiles in CD34+ cells

“…Several GEA studies of patient-derived CD34 + cells have been conducted to investigate deregulated gene expression in MPN [12][13][14][15][16][17]. However, not all disease entities were included, thereby impeding a direct comparison of the different entities among themselves and/or their normal counterparts.…”