CKβ8-1 alters expression of cyclin E in colony forming units-granulocytemacrophage (CFU-GM) lineage fromhuman cord blood CD34+ cells

A C6 β-chemokine, CKβ8-1, suppressed the colony formation of CD34+cells of human cord blood (CB). Molecular mechanisms involved in CKβ8-1-medi-cated 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 sig-nificantly alter the expression of the G1/S cycle regulation proteins (cyclin D1, D3, and E), CDK in-hibitor (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 CFU-GM lineage develop-ment. These findings suggested that cyclin E may play a role in suppressing the colony formation of CFU-GM by CKβ8-1. KCI Citation Count: 4