Evidence of a Conserved Regulatory Circuit Between Mex-3 andGLD-1 Through Analysis of Tino/hMEX-3D Binding Sequence

B-cell lymphomas are characterized by clonal expansion of tumor cells expressing a B Cell Receptor (BCR) that include idiotypic immunoglobulin (Id). Id is determined by rearrangements of the immunoglobulin V regions that are unique for each clonal Bcell population and functions as a tumor-specific marker. Random peptide libraries (RPL) are important tools to define the antigen specificity and the characterization of Id ligands for tumor B cells. We evaluated the ability of Id-specific peptide (Idpeptides) for B-lymphoma cells selected by screening RPLs as a tool for the specific delivery of a therapeutic cargo into tumor cell. Results can be summarized as follows: a) 3 phage clones selected screening RPLs with immunoglobulins purified from A20 B- lymphoma cells b) Synthetic peptides, corresponding to the insert of phage clones, maintained their antigenic properties c) Id-peptides targeted specifically tumor cells in vivo d) Id-peptides were internalized into target tumor cells e) Id-peptides were able to deliver a cargo fluorophore (FITC) or a protein (GFP) into target tumor cells. This evidence shows that Id-peptides are powerful candidates for specific delivery of therapeutic drugs into tumors.