Publication Date:
2019-11-13
Description:
Introduction. Runt-related transcription factor 1 (RUNX1) is a transcription factor critical for normal and leukemic hematopoiesis. Three main isoforms, RUNX1 i-1a, i-1b and i-1c, are produced through alternative splicing of RUNX1. Unlike i-1b and i-1c, i-1a has a Runt homology domain (RHD) but lacks the transactivation domain (TAD), and inhibits transcriptional activity of -1b by competing with higher affinity for target gene sequences. Overexpression of i-1a in cell lines inhibits terminal myeloid differentiation. The i-1a is expressed at high levels in patients (pts) with acute myeloid leukemia (AML). Mutations of RUNX1 are common in CMML and MDS, whereas incidence and clinical correlates of RUNX1 mutations in MPNs are poorly known. Aim: To analyze the spectrum and clinical correlates of RUNX1 genetic abnormalities (RUNX1-abn), and the expression of RUNX-1a isoform, in a large series of pts with MPNs. Methods. 686 MPN pts (50 PV, 165 ET, 154 overt-PMF, 143 prefibrotic-PMF, 74 PPV-MF and 100 PET-MF, diagnosed according to 2016 WHO) were included in the study; of these, 625 were analyzed in chronic phase (CP) and 61 at leukemic transformation (LT; of a total of 106 LTs, 58%), including 29 cases with paired samples at diagnosis and LT. Established methods were used for JAK2, MPL and CALR genotyping. A high molecular risk (HMR) category was defined according to Vannucchi A, [Leukemia 2013]. Ion Torrent NGS platform was used to genotype all RUNX1 coding sequence. In 21/29 paired samples, a long reads genome sequencing by Oxford Nanopore technology (ONT) was performed. Copy number variation (CNV) analysis was performed with NanoGLADIATOR package [Magi A, Genome Biol 2019]. Differential expression of RUNX1 mRNA isoform1a and 1b was analyzed by qRT-PCR. Nonparametric Wilcoxon rank-sum test, Kaplan-Meier estimates and log-rank test were used as appropriate. Results. Somatic RUNX1 mutations were identified in 31 pts (4.5%): 14/625 in CP (2.2%) and 17/61 in LT (27.9%; P1 of these genes in 16/21 (76%) pts at LT vs 2/16 (12.5%) of CP pts. After median follow-up of 4.9y (range 0.1-36.2y) 273 pts died (39.8%). 106 pts (15.4%) progressed to AML after median of 4.7y (0.1-36.2y) from diagnosis. Incidence of LT differed significantly among diseases: 3 pts in PV (5.9%), 17 in ET (10.1%), 39 in overt-PMF (23.5%), 12 in prefibrotic-PMF (8.3%), 11 in PPV-MF (14.1%) and 24 in PET-MF (22.6%). RUNX1-abn were detected, respectively, in 100%, 53.0%, 23.1%, 41.7%, 36.4% and 12.5% of cases at either CP and/or LT. Leukemia-free survival (LFS) was shorter in pts harboring RUNX1-abn in CP compared to RUNX1-WT pt (2.8y vs NR; P
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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