Myeloid Metaplasia Myelofibrosis Research Articles

Enhanced HDAC (Histone Deacetylase) Enzyme Activities in Blood CD 34 + Cells in Patients with Myeloid Metaplasia Myelofibrosis (MMM).

We previously reported that histone deacetylase (HDAC) activity is elevated, but is not correlated to the JAK-2 mutation status, in patients with myelofibrosis myeloid metaplasia (MMM) (Blood 107:319b 2005). Now we have studied more patients: totally, 17 with MMM, 19 with other myeloproliferative disorders (MPD), and 16 normal volunteers as controls. Significantly elevated HDAC levels again was shown in patients with MMM compared with other MPD patients and normal volunteer controls (p<0.05). Sixteen patients with MMM were also studied for correlation between JAK-2 mutation status and HDAC levels; no significant correlation was found. We then studied which members of HDACs were elevated in patients with MMM. cDNA was prepared from total RNA obtained from blood CD 34+ cells; then QRT-PCR was performed using pre-made mixtures of primer and FAMTAMRA-labeled probes from ABI (www.appliedbiosystems.com). Primers and probe to GAPDH were used as internal controls. Cycle threshold (Ct) values were obtained graphically for target genes and internal control GAPDH gene products. Amplification efficiencies were calculated by plotting Ct s from serial diluted cDNAs for target genes and GAPDH and all with slopes below 0.1. Δ Ct values were obtained by subtracting GAPDH Ct from target gene Ct. Relative mRNA levels were determined by subtraction of normal control Δ Ct values from MMM Δ Ct values to give ΔΔ Ct values, which were converted to 2− ΔΔ Ct (Relative Quantitation of Gene Expression). The results showed elevated HDAC1 (2.80), HDAC2 (18.45), HDAC3 (2.10), HDAC 6 (2.03) HDAC 9 (2.71), SIRT3 (70.20), and SIRT6 (39.40) and depressed HDAC4 (0.01), HDAC5 (0.001), HDAC8 (0.001), SIRT2 (0.23), SIRT5 (0.005), and SIRT7 (0.88). () indicates relative mRNA values of MMM to controls. These results suggest that HDAC activities are elevated in patients with MMM and are elevated in many members of HDAC. This study may lay the basis for using HDAC inhibitors in clinical trials treating patients with MMM.

X-inactivation–based clonality analysis and quantitative JAK2V617F assessment reveal a strong association between clonality and JAK2V617F in PV but not ET/MMM, and identifies a subset of JAK2V617F-negative ET and MMM patients with clonal hematopoiesis

The JAK2V617F mutation is present in most patients with polycythemia vera (PV) and in some patients with essential thrombocythemia (ET) and myeloid metaplasia/myelofibrosis (MMM). We sought to investigate the relationship between granulocyte clonality and JAK2V617F allelic ratio. A total of 168 of 190 female patients were informative for a clonality assay at the HUMARA locus; 80% of MMM, 75% of PV, and 67% of ET patients demonstrated clonal granulopoiesis. The JAK2V617F allele was detected by quantitative real-time polymerase chain reaction (PCR) in 99% of PV, 72% of ET, and 39% of MMM. A correlation between clonality and JAK2V617F allelic ratio was demonstrated for PV (P < .001) but not for ET or MMM (both P > .6). These data suggest that acquisition of the JAK2V617F mutation may be sufficient for the development of PV, but additional genetic events are necessary in ET and MMM. In addition, some ET and MMM patients with clonal granulopoiesis have somatic mutations other than JAK2V617F.