Differentially Expressed MicroRNAs in Conservatively Treated Nontraumatic Osteonecrosis Compared with Healthy Controls

Deregulation of microRNAs (miRNAs) contributes to nontraumatic osteonecrosis of the femoral head (ONFH-N), but the differentially expressed circulating miRNAs in patients with ONFH-N receiving nonsurgical therapy are unknown. This study aimed to determine the miRNAs expression profile of patients with ONFH-N receiving conservative treatments. This was a case-control prospective study of 43 patients with ONFH-N and 43 participants without ONFH-N, enrolled from 10/2014 to 10/2016 at the Department of Orthopedics of the Linyi People’s Hospital (China). The two groups were matched for age, gender, and living area. Microarray analysis and quantitative RT-PCR were used to examine the differentially expressed miRNAs. Bioinformatics was used to predict miRNA target genes and signaling pathways. Microarray and quantitative RT-PCR revealed that nine miRNAs were downregulated and five miRNAs were upregulated in ONFH-N(n=3)compared with controls(n=3). Bioinformatics showed that calcium-mediated signaling pathway, regulation of calcium ion transmembrane transporter activity, cytoskeletal protein binding, and caveolae macromolecular signaling complex were probably regulated by the identified differentially expressed miRNAs. In the remaining 80 subjects (n=40/group), miR-335-5p was downregulated(P=0.01)and miR-100-5p was upregulated(P=0.02)in ONFH-N compared with controls. In conclusion, some miRNAs are differentially expressed in conservatively treated ONFH-N compared with controls. Those miRNAs could contribute to the pathogenesis of ONFH-N.

VEGFR-1 (FLT-1), β1 integrin, and hERG K+ channel for a macromolecular signaling complex in acute myeloid leukemia: role in cell migration and clinical outcome

Leukemia cell motility and transendothelial migration into extramedullary sites are regulated by angiogenic factors and are considered unfavorable prognostic factors in acute leukemias. We have studied cross talk among (1) the vascular endothelial growth factor receptor-1, FLT-1; (2) the human eag-related gene 1 (hERG1) K+ channels; and (3) integrin receptors in acute myeloid leukemia (AML) cells. FLT-1, hERG1, and the β1 integrin were found to form a macromolecular signaling complex. The latter mostly recruited the hERG1B isoform of hERG1 channels, and its assembly was necessary for FLT-1 signaling activation and AML cell migration. Both effects were inhibited when hERG1 channels were specifically blocked. A FLT-1/hERG1/β1 complex was also observed in primary AML blasts, obtained from a population of human patients. The co-expression of FLT-1 and hERG1 conferred a pro-migratory phenotype to AML blasts. Such a phenotype was also observed in vivo. The hERG1-positive blasts were more efficient in invading the peripheral circulation and the extramedullary sites after engraftment into immunodeficient mice. Moreover, hERG1 expression in leukemia patients correlated with a higher probability of relapse and shorter survival periods. We conclude that in AML, hERG1 channels mediate the FLT-1–dependent cell migration and invasion, and hence confer a greater malignancy.

VEGFR-1 (FLT-1), b1 Integrin and hERG K+ Channel Form a Macromolecular Signaling Complex in Acute Myeloid Leukemia Cells.

Acute myeloid leukemia (AML) is a heterogeneous group of clonal bone marrow (BM) malignancies, presenting a wide spectrum of morphologic, immunophenotypic, cytogenetic, and molecular features. There is general agreement that persistent detection of leukemia cells outside the BM microenvironment, especially when accompanied by infiltration into extramedullary sites, is a clear negative prognostic factor. Infiltration may also reduce leukemia responsiveness to induction chemotherapy. Great attention is thus being played to the molecular mechanisms that regulate acute leukemia cells exit from the BM. A crucial role is thought to be played by the angiogenic factors and angiogenesis-related signals, that operate inside the BM microenvironment.The persistence of circulating leukemia blasts and their engraftment into extramedullary sites are negative prognostic factors, in patients with acute leukemia. Leukemia cell exit from the bone marrow is regulated by angiogenic factors and in particular by the Vascular Endothelial Growth Factor and its receptor 1, FLT-1. We have studied the cross talk between FLT-1, the human eag-related gene 1 (hERG1) K+ channels, integrin receptors, in acute myeloid leukemia (AML) cells. FLT-1, hERG1 and the b1 integrin were found to form a macromolecular signaling complex. The latter mostly recruited the hERG1B isoform of hERG1 channels, and its assembly was necessary for subsequent FLT-1 tyrosine phosphorylation and sustained AML cell migration. What is more, both effects were inhibited when hERG1 channel were specifically blocked. The formation of an FLT-1/hERG1/b1 complex was also observed in primary AML blasts, obtained from a population of human patients. The coexpression of FLT-1 and hERG1 conferred a pro-migratory phenotype to these AML blasts. Such a phenotype was also observed in vivo. Herg1 positive blasts were more efficient in invading the peripheral circulation and the extramedullary sites after engraftment into immunodeficient mice. Moreover, herg1 expression in leukemia patients correlated with a shorter overall survival. Overall, we conclude that hERG1 channels mediate the FLT-1 dependent AML cell migration and that their expression is a negative prognostic factor, in AML.