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: Sun J Choi, Tomoko Oba, Natalie S Callander, Diane F Jelinek, G David Roodman
• Journal: Blood (Blood) Vol. 101 Issue 10 Pg. 3778-83 (May 15 2003) ISSN: 0006-4971 [Print] United States
• PMID: 12560229 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Chemokine CCL3
• Chemokine CCL4
• Core Binding Factor Alpha 2 Subunit
• DNA-Binding Proteins
• Macrophage Inflammatory Proteins
• Protein Isoforms
• Proto-Oncogene Proteins
• RNA, Messenger
• RUNX1 protein, human
• Transcription Factors

Topics

• Base Sequence
• Cells, Cultured
• Chemokine CCL3
• Chemokine CCL4
• Cloning, Molecular
• Core Binding Factor Alpha 2 Subunit
• DNA-Binding Proteins (genetics, metabolism)
• Gene Expression Regulation, Neoplastic (physiology)
• HL-60 Cells
• Humans
• Macrophage Inflammatory Proteins (genetics)
• Molecular Sequence Data
• Multiple Myeloma (genetics)
• Promoter Regions, Genetic
• Protein Isoforms (genetics, metabolism)
• Proto-Oncogene Proteins (genetics, metabolism)
• RNA, Messenger (genetics)
• Reverse Transcriptase Polymerase Chain Reaction
• Transcription Factors (genetics, metabolism)
• Transcription, Genetic
• Tumor Cells, Cultured
• U937 Cells