Specific down-regulation of annexin II expression in human cells interferes with cell proliferation

The protein-tyrosine kinase substrate annexin II is a growth regulated gene whose expression is increased in several human cancers. While the precise function of this protein is not understood, annexin II is proposed to be in volved in multiple physiological activities, including DNA synthesis and ce ll proliferation. Targeted disruption of the annexin II gene affects calciu m signaling, tyrosine phosphorylation and apoptosis, indicating the importa nt physiological role of this protein. We used a transient co-transfection assay to regulate annexin II expression in human HeLa, 293 and 293T cells, and measured the effects of annexin II down regulation on DNA synthesis and proliferation. Transfection of cells with an antisense annexin II vector r esults in inhibition of cell division and proliferation, with concomitant r eduction in annexin II message and protein levels. Cellular DNA synthesis i s significantly reduced in antisense transfected cells. Replication extract s made from antisense transfected cells have significantly reduced efficien cy to support SV40 in vitro DNA replication, while the extracts made from s ense transfected cells are fully capable of replication. Our results indica te an important role of annexin II in cellular DNA synthesis and cell proli feration.