Expression of the annexin VIII gene in acute promyelocytic leukemia.

Annexin VIII is preferentially expressed in APL, but its level of expression in other subtypes of AML is much lower. Annexin VIII was originally found to be a vascular anticoagulant, but evidence obtained from our recent studies suggests that it does not play a role in hemorrhage diathesis in APL. The specific expression of annexin VIII in APL may relate to its possible role in hematopoietic cell differentiation. The expression of annexin VIII is developmentally regulated in APL-derived NB4 cells. It can be downregulated as a response to induction by ATRA, an agent which is also capable of inducing maturation of NB4 cells. Our current understanding is that annexin VIII is most likely involved in signal transduction and may have a role as a modulator of PKC. A change in cellular PKC activity is expected to have a significant impact on cell differentiation and proliferation. The biological function of annexin VIII is currently unknown, but its expression in APL and its possible role in differentiation and proliferation of the leukemia cells would provide an excellent model system to study and elucidate this intriguing question.