CKβ8-1 alters expression of cyclin E in colony forming units-granulocyte macrophage (CFU-GM) lineage from human cord blood CD34⁺ cells

Abstract

A C6 β-chemokine, CKβ8-1, suppressed the colony formation of CD34⁺ cells of human cord blood (CB). Molecular mechanisms involved in CKβ8-1-medicated suppression of colony formation of CD34⁺ cells are not known. To address this issue, the level of various G1/S cell cycle regulating proteins in CKβ8-1-treated CD34⁺ cells were compared with those in untreated CD34⁺ cells. CKβ8-1 did not significantly alter the expression of the G1/S cycle regulation proteins (cyclin D1, D3, and E), CDK inhibitor (p27and Rb), and other cell proliferation regulation protein (p53) in CB CD34⁺ cells. Here we describe an in vitro system in which CB CD34⁺ cells were committed to a multipotent progenitor lineage of colony forming units-granulocyte/macrophage (CFU-GM) by a simple combination of recombinant human (rh) GM-CSF and rhIL-3. In this culture system, we found that cyclin E protein appeared later and disappeared faster in the CKβ8-1-treated cells than in the control cells during CFU-GM lineage development. These findings suggested that cyclin E may play a role in suppressing the colony formation of CFU-GM by CKβ8-1.