AbstractBACKGROUNDThe α2 chain of the interleukin‐13 receptor (IL13Rα2) is a high‐affinity receptor and a candidate target for cytotoxic killing of cancer cells. Availability of a human prostate cancer cell line with high level of IL13Rα2 expression will facilitate the development of therapeutic modalities.METHODSARCaPE and ARCaPM human prostate cancer cell lines were subjected to comparative analyses of gene expression. Expression of the IL13Rα2 protein was confirmed by Western blotting and immunostaining. IL13Rα2 proteins in xenograft tumors and clinical human prostate cancer specimens were detected by specific antibodies. LNCaP prostate cancer cells stably transfected with IL13Rα2 were examined for accelerated growth in athymic mice.RESULTSWe found that IL13Rα2 proteins could be detected in both the ARCaPE and ARCaPM cells, but the expression level in ARCaPM was more than 17‐fold higher than in ARCaPE cells. Importantly, the ARCaP lineage represented the only human prostate cancer cell line that expresses IL13Rα2 proteins at the level detectable by Western blotting. Expression of IL13Rα2 was accompanied by resistance to the anti‐tumor activity of interleukin‐13 (IL‐13). ARCaP cells were found to be insensitive to growth inhibition upon IL‐13 treatment, while overexpression of IL13Rα2 in LNCaP cells promoted intratibial tumor growth in athymic mice.CONCLUSIONSDifferential IL13Rα2 expression may account for the high tumorigenic and metastatic potential of ARCaPM cells. The unique expression of IL13Rα2 makes ARCaP lineage an attractive model for evaluating the targeting efficacy of therapeutic agents based on IL13Rα2 protein expression. Prostate © 2010 Wiley‐Liss, Inc.