Objective    To observe Wnt5a expression in acute and chronic myeloid leukemia and the effect of exogenous Wnt5a on the growth of K562 cell lines.    Methods     Peripheral blood or bone marrow samples from 5 patients of acute myeloid leukemia and 6 of chronic myeloid leukemia

as well as leukemia cell lines were analyzed for the expression of Wnt5a by RT-PCR. Wnt5a and GFP condition medium was prepared by collecting supernatant 24-48 h from recombinant adenovirus vector AdWnt5a and AdGFP infecting CHO cells. The effect of condition medium containing Wnt5a on the growth of K562 cells was studied by cell counting

trypan blue staining and cell morphology observation.    Results    Wnt5a was not expressed in all 6 cases of chronic myeloid leukemia

K562 HL-60

or CHO cell lines

and not expressed or weakly expressed in 4 cases of acute myeloid leukemia. Wnt5a was strongly expressed in Jurkat cells and only one case of acute myeloid leukemia that was in complete remission. The growth of K562 cells was inhibited after treated by Wnt5a condition medium

but their viability was not affected. K562 displayed differentiation phenotypes to some extent as compared with control cells.    Conclusion    Exogenous Wnt5a can inhibit K562 cells growth and induce differentiation. Down-regulated expression of Wnt5a may relate to leukemia genesis.