Abstract 4967: Changes in c-Myb specificity and activities during the cell cycle in T-ALL and AML

• Published in: Cancer research (Chicago, Ill.) Vol. 70; no. 8_Supplement; p. 4967
• Main Authors: Quintana, Anita M., Pena, Janeth J., Ness, Scott A.
• Format: Journal Article
• Language: English
• Published: 15.04.2010
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM10-4967

Abstract The c-Myb transcription factor is a critical regulator of proliferation and stem cell differentiation, and mutated alleles of c-Myb are oncogenic, but little is known about the activities of c-Myb during the cell cycle. Previous studies showed that c-Myb interacts with the cell cycle regulators Cyclin D1 and Cyclin Dependent Kinases 4 and 6, suggesting that c-Myb activity is regulated during the cell cycle. We set out to test that directly, using Chromatin ImmunoPrecipitation (ChIP) assays capable of assessing the activities of c-Myb in primary and flow sorted populations of cells. We performed ChIP assays with cells sorted into each phase of the cell cycle to determine c-Myb specificity and correlated c-Myb occupancy with the relative expression of a number of known target genes. Briefly, asynchronously growing cells were fixed, stained with Hoechst 33342, then flow-sorted into different cell cycle phase populations before processing the samples for ChIP assays. The c-Myb protein associated with different cyclin gene promoters in different stages of the cell cycle, showing that c-Myb specificity and activity are dynamic. By using several different anti-Myb antibodies, we confirmed that the changes were due to relocalization of c-Myb, and not due to changes in the accessibility of individual epitopes. We also analyzed the Myb-regulated CXCR4 gene promoter in both primary AML and Jurkat T-ALL cells. c-Myb occupied the CXCR4 gene promoter during S and G2/M phase of the cell cycle, which correlated with increased CXCR4 expression in cycling cells. In conclusion, our data demonstrate that c-Myb specificity is dynamic, that c-Myb associates with different genes in different phases of the cell cycle and that c-Myb is cell cycle regulated in both T-ALL and primary human AML. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4967.