title: AML-1A and AML-1B regulation of MIP-1alpha expression in multiple myeloma.
abstract: Macrophage inflammatory protein-1alpha (MIP-1alpha) is produced in high concentration by multiple myeloma (MM) cells in about 70% of patients, and MIP-1alpha levels correlate with their disease activity. Patients who have high levels of MIP-1alpha have a poor prognosis. Furthermore, blocking MIP-1alpha expression in an in vivo model of human MM profoundly decreases both tumor burden and bone destruction, suggesting that MIP-1alpha is an important mediator of MM bone disease. Therefore, to analyze the regulation of MIP-1alpha production in MM, we cloned the human MIP-1alpha promoter and characterized the transcription factor (TF) motifs that control MIP-1alpha expression in MM cells. The proximal region of MIP-1alpha promoter was composed of 2 sets of identical transcription regulatory regions consisting of GATA-2(+) AML-1(+) C/EBPalpha motifs. Since 2 alternatively spliced variants of the acute myeloid leukemia-1 (AML-1) class of TFs can bind the AML-1 region, AML-1A and AML-1B, the relationship between the expression levels of AML-1A or AML-1B in MM cells and their capacity to express MIP-1alpha was examined. AML-1A mRNA was relatively overexpressed compared with AML-1B in MM cell lines that produced high levels of MIP-1alpha (> 1 ng/mL per 10(6) cells per 72 hours), but AML-1A was not increased in MM cell lines that expressed less than 200 pg/mL MIP-1alpha. More importantly, the ratio of AML-1A to AML-1B mRNA levels was also increased in 3 of 3 highly purified myeloma cells from patients with MM who expressed increased amounts of MIP-1alpha. The ratio of AML-1A to AML-1B mRNA in patients with MM was 8-fold higher than in healthy controls. Transduction of AML-1B into the MM-derived MM.1S and ARH-77 cells totally blocked MIP-1alpha production, while AML-1A did not further increase the already high levels of MIP-1alpha produced by these cells. Taken together, these data demonstrate that in patients with MM who produce increased concentrations of MIP-1alpha, the relative level of AML-1B is significantly decreased compared with healthy controls. The data suggest that strategies that enhance AML-1B expression or decrease AML-1A in MM cells may be beneficial therapeutically.
authors.affiliation: Department of Medicine Hematology/Oncology, University of Pittsburgh, PA, USA.
authors.forename: Sun J
authors.initials: SJ
authors.lastname: Choi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Oba
authors.forename: Natalie S
authors.initials: NS
authors.lastname: Callander
authors.forename: Diane F
authors.initials: DF
authors.lastname: Jelinek
authors.forename: G David
authors.initials: GD
authors.lastname: Roodman
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D003001:Cloning, Molecular; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D018922:HL-60 Cells; D006801:Humans; D019402:Macrophage Inflammatory Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000235:genetics*; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D020298:U937 Cells
chemical_list: D054405:Chemokine CCL3; D054407:Chemokine CCL4; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D019402:Macrophage Inflammatory Proteins; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; C493728:RUNX1 protein, human; D014157:Transcription Factors