ANTISENSE OLIGONUCLEOTIDE INHIBITION OF ACETYLCHOLINESTERASE GENE-EXPRESSION INDUCES PROGENITOR-CELL EXPANSION AND SUPPRESSES HEMATOPOIETICAPOPTOSIS EX-VIVO

To examine the role of acetylcholinesterase (EC 3.1.1.7) in hematopoie tic cell proliferation and differentiation, we administered a 15-mer p hosphorothioate oligonucleotide, antisense to the corresponding ACHE g ene (AS ACHE), to primary mouse bone marrow cultures. Within 2 hr of A S-ACHE addition to the culture, ACHE mRNA revels dropped by approximat e to 90%, as compared with those in cells treated with the ''sense'' o ligomer, S-ACHE. Four days after AS-ACHE treatment, ACHE mRNA increase d to levels 10-fold higher than in S-ACHE cultures or in fresh bone ma rrow. At this later time point, differential PCR display revealed sign ificant differences between cellular mRNA transcripts in bone marrow a nd those in AS-ACHE- or S-ACHE-treated cultures. These oligonucleotide triggered effects underlay considerable alterations at the cellular l evel: AS-ACHE but not S-ACHE increased cell counts, reflecting enhance d proliferation, In the presence of erythropoietin it also enhanced co lony counts, reflecting expansion of progenitors. AS-ACHE further supp ressed apoptosis-related fragmentation of cellular DNA in the progeny cells, and it diverted hematopoiesis toward production of primitive bl asts and macrophages in a dose-dependent manner promoted by erythropoi etin. These findings suggest that the hematopoietic role of acetylchol inesterase, anticipated to be inverse to the observed antisense effect s, is to reduce proliferation of the multipotent stem cells committed to erythropoiesis and megakaryocytopoiesis and macrophage production a nd to promote apoptosis in their progeny. Moreover, these findings may explain the tumorigenic association of perturbations in ACHE gene exp ression with leukemia.