Prognostic and biological significance of the proangiogenic factor EGFL7 in acute myeloid leukemia

Abstract

Epithelial growth factor-like 7 (EGFL7) is a protein that is secreted by endothelial cells and plays an important role in angiogenesis. Although EGFL7 is aberrantly overexpressed in solid tumors, its role in leukemia has not been evaluated. Here, we report that levels of both EGFL7 mRNA and EGFL7 protein are increased in blasts of patients with acute myeloid leukemia (AML) compared with normal bone marrow cells. High EGFL7 mRNA expression associates with lower complete remission rates, and shorter event-free and overall survival in older (age ≥60 y) and younger (age <60 y) patients with cytogenetically normal AML. We further show that AML blasts secrete EGFL7 protein and that higher levels of EGFL7 protein are found in the sera from AML patients than in sera from healthy controls. Treatment of patient AML blasts with recombinant EGFL7 in vitro leads to increases in leukemic blast cell growth and levels of phosphorylated AKT. EGFL7 blockade with an anti-EGFL7 antibody reduced the growth potential and viability of AML cells. Our findings demonstrate that increased EGFL7 expression and secretion is an autocrine mechanism supporting growth of leukemic blasts in patients with AML. EGFL7 | acute myeloid leukemia | clinical outcomeA cute myeloid leukemia (AML) is a clonal hematopoietic disease characterized by the proliferation of immature blasts in the bone marrow (BM) and blood (1). Genetic alterations, including chromosomal translocations and deletions and gene mutations leading to aberrant downstream target gene expression, contribute to AML initiation and maintenance. Previously, our group demonstrated that increased miRNA-126-3p (miR-126) expression in patients with cytogenetically normal AML (CN-AML) correlated with shorter overall survival (OS). Furthermore, we found miR-126 to be essential for leukemia stem cell (LSC) homeostasis, and in vivo targeting of miR-126 in a patientderived xenograft model resulted in prolonged survival in secondary bone marrow transplant (BMT) recipients (2). miR-126 is located within intron 7 of a protein-coding gene known as Epithelial growth factor-like 7 (EGFL7) (3). Although we and others (2, 4, 5) have shown an important role for miR-126 in AML biology, we know of no studies that have been performed to understand the prognostic and functional implications of expression of its host gene, EGFL7, in AML.EGFL7 is a secreted protein of ∼30 kDa and plays an important physiological role in angiogenesis (6-8). Unlike other angiogenic factors (e.g., VEGF), physiological EGFL7 expression and function has been restricted mainly to the endothelial cells where it regulates survival, migration, and differentiation (6). Aberrant expression of EGFL7 has been shown to be involved in tumor growth and disease progression of several solid tumors, including hepatocellular carcinoma, malignant glioma, and breast, lung, and pancreatic cancers (9), but its role in hematopoietic malignancies is currently unknown. Therefore, we investigated the prognostic and biological function of EGFL7 expression in A...

PRESTO, a new tool for integrating large-scale -omics data and discovering disease-specific signatures

“…Separate studies described nine of the 10 genes in this signature as being clinically correlated to cancer pathophysiology or prognosis [44][45][46][47][48][49][50][51][52][53] . PRESTO was able to discover known AML-related genes even though it was blinded to the sample designation, demonstrating biological relevance of the technique.…”

“…Removal of the stemness genes (SOCS2, BEX3, and CPXM1) leads to a unique 10-gene (Signature C), which still predicts survival at the same level of significance. 9 of these genes have been described in AML or other cancers (Table 1) [44][45][46][47][48][49][50][51][52][53] . One gene, SHANK3, is completely novel.…”

State-Transition Analysis of Time-Sequential Gene Expression Identifies Critical Points That Predict Leukemia Development

“…Notably, Egfl7, Wt1 and Prkd1 are among the persistent differentially expressed genes at all critical points c1, c2, and c3 during leukemia state-transition. Egfl7 is known to be highly expressed and predict poor prognosis in AML (Papaioannou et al, 2017), and is also a host gene of miR-126, which is a miRNA signature associated with inv(16) AML (Li et al, 2008).…”

“…For instance, considering the expression of Kit and CM genes, we showed that the magnitude of the second component of both genes was Page 15 of 40 negative ( * * < 0) with yyyyy⃗ = (−0.0060, −0.0284) and yyyyyy⃗ = (−0.0042, −0.0202), confirming their contribution to promote leukemia development ( Figure 6B). Notably, the proangiogenic factor Egfl7 [ 7 yyyyyyyyyyyyy⃗ = (−0.0009, −0.039)] (Papaioannou et al, 2017), leukemia-associated antigen Wt1 ( Figure 6B). Consistent with a positive contribution promoting leukemia progression, all CM mice that developed leukemia (CM1-5, CM7) showed increasing expression of these leukemia eigengenes (Kit, CM, Egfl7, Wt1, Prkd1) and reproducible trajectories as they move from normal hematopoiesis ( + * ) to leukemia ( ) ) ( Figure 6C).…”

Expression significance and potential mechanism of hypoxia‐inducible factor 1 alpha in patients with myelodysplastic syndromes

“…Various types of angiogenesis factors were observed in the bone marrow of patients with AML or MDS, including vascular endothelial growth factor (VEGF), fibroblast growth factor (bFGF), angiogenin, angiogenin‐1, platelet‐derived growth factor (PDGF), hepatocyte growth factor (HGF), epidermal growth factor (EGF), tumor necrosis factor alpha (TNF‐α), transforming growth factor alpha (TGF‐α), and transforming growth factor beta (TGF‐β). Most of these factors were secreted by hematopoietic cells in tumors, promoting the growth and proliferation of leukemia cells via an autocrine mechanism …”