B103

Aquaporins (AQPs) are water channel proteins that facilitate transcellular water movements. H        uman AQPs have previously been associated with increased expression in solid tumors. Recent reports suggest the role of AQP5 in promoting cancer progression,         providing a potential basis for designing a novel therapy targeting AQP5        . However, its expression pattern in hematologic malignancies has not been described yet. Thus, here, we have performed flow cytometry analysis with bone marrow samples of human leukemic patients (n=47). We have found that AQP5 is expressed in human leukemia (57.4%, 27/47) including acute myeloid leukemia (13/22), acute lymphoblastic leukemia (6/10), and chronic myelogenous leukemia (7/14) and chronic lymphocytic leukemia (1/1). However, normal bone marrow samples (n=5) did not show any expression of AQP5. Among 47 samples, cells with only surface expression of AQP5 were 8 (17.0%), cells with only cytoplasmic expression were 12 (25.5%), and cells with both surface and cytoplasmic expression were 7 (14.9%). Of interest, the association between AQP5 expression and resistance in chemotherapy was suggestive (chi square test, p=0.059). 7 out of 8 relapse cases expressed AQP5. Intriguingly, the odds of developing relapse in patients with AQP5 expression (7/20) was 6.7 times that in patients without AQP5 expression (1/19).

In summary, our report demonstrates for the first time that human AQP5 is expressed in all types of primary human leukemic cells. It also provides a basis for pursuing its possible role in the progression of human blood cancers as in solid tumors.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):B103.

Seventh AACR International Conference on Frontiers in Cancer Prevention Research-- Nov 16-19, 2008; Washington, DC