Abstract A166: A small molecule inhibitor of Pirin that suppresses tumor cell migration

Abstract

Abstract Background: Bcl-3 was originally identified as a putative proto-oncogene which was frequently rearranged in chronic B cell lymphocytic leukemia. Bcl-3 is a member of the I B family which modulates the activities of NF- B/Rel transcription factors. Pirin is known to be bound to Bcl-3, and expression of Pirin was observed in some tumor cell lines, however, the exact roles of Pirin in tumor cells have not been identified. Materials and Methods: Chemical array screening - Previously, we have developed a nonselective immobilization method that makes possible the introduction of a variety of small molecules to the glass slides. To obtain the small molecules binding to Pirin, we treated the chemical array with cell lysate containing the fusion protein of Pirin-red fluorescent protein. The interaction of Pirin and small molecules was detected by a fluorescence image scanner. Results: We found the compound, designated compound A, could bind to Pirin by using chemical array screening. We could not detect any interactions of compound A with other proteins we tested. Moreover, we carried out the pull-down assay with compound A-agarose beads, and identified Pirin as compound A-binding protein from the total cell lysate, suggesting the specificity of compound A to Pirin. Recombinant Pirin could bind to recombinant ankyrin repeat domain of Bcl-3, and the interaction was interfered by the treatment with compound A. To clarify the role of Pirin in tumor cells, we treated of the cells with compound A. We found that treatment of the cultured tumor cells with compound A or Pirin-targeted siRNA resulted in suppression of migration, but not cell proliferation. Conclusion: By use the small molecule and siRNA, it is suggested that Pirin regulates migration of the tumor cells, and the inhibitor of Pirin might be a new chemotherapeutic potential for invasive tumors. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A166.