CNF TOXINS AND HYPERPLOIDY 3467 Fluorescence - Activated Cell Sorting ( FACS } Analysis Cells

Cytotoxic necrotizing factor (CNF) toxins, isolated from certain Escherichia coli strains known t o cause intestinal and extra intestinal infections, induce reorganization of the actin cytoskeleton and generate hyperploidy in adherent cell lines. We have examined the effect of CNF toxin on one of the few cell types that naturally increase nuclear DNA content, megakaryocytes. Our studies show that only hematopoietic cells capable of differentiating along the megakaryocyte lineage responded t o the CNFZ toxin by becoming polyploid and by reorganizing actin. The K562, HEL, and CHRF-288-11 cell lines can be induced with phorbol ester t o differentiate along the megakaryocyte lineage, and these cells also respond t o the toxin with increased DNA content and actin cytoskeletal rearrangements. Interestingly, treatment of the K562 and HEL cell lines with CNF2 does not result in an increase in production of the megakaryocytic marker glycoprotein Illa, unlike phorbol ester treatment. Conversely, two