RT Journal Article SR Electronic T1 A Novel Tumor-Targeted Therapy Using a Claudin-4-Targeting Molecule JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 918 OP 926 DO 10.1124/mol.109.058412 VO 76 IS 4 A1 Rie Saeki A1 Masuo Kondoh A1 Hideki Kakutani A1 Shin-ichi Tsunoda A1 Yasuhiro Mochizuki A1 Takao Hamakubo A1 Yasuo Tsutsumi A1 Yasuhiko Horiguchi A1 Kiyohito Yagi YR 2009 UL http://molpharm.aspetjournals.org/content/76/4/918.abstract AB Carcinogenesis is often accompanied by dysfunctional tight junction (TJs), resulting in the loss of cellular polarity. Claudin, a tetra-transmembrane protein, plays a pivotal role in the barrier and fence functions of TJs. Claudin-4 is deregulated in various cancers, including breast, prostate, ovarian, and gastric cancer. Claudin-4 may be a promising target molecule for tumor therapy, but the claudin-targeting strategy has never been fully developed. In the present study, we prepared a claudin-4-targeting molecule by fusion of the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) with the protein synthesis inhibitory factor (PSIF) derived from Pseudomonas aeruginosa exotoxin. PSIF was not cytotoxic to claudin-4-expressing cells, whereas C-CPE-PSIF was cytotoxic. Cells that express claudin-1, -2, and -5 were less sensitive to C-CPE-PSIF. Pretreatment of the cells with C-CPE attenuated C-CPE-PSIF-induced cytotoxicity, and mutation of C-CPE in the claudin-4-binding residues attenuated the cytotoxicity of C-CPE-PSIF. TJ-undeveloped cells were more sensitive to C-CPE-PSIF than TJ-developed cells. It is noteworthy that polarized epithelial cells are sensitive to C-CPE-PSIF applied to the basal side, whereas the cells were less sensitive to C-CPE-PSIF applied to the apical side. Intratumoral injection of C-CPE-PSIF reduced tumor growth. This is the first report to indicate that a claudin-4-targeting strategy may be a promising method to overcome the malignant tumors. © 2009 The American Society for Pharmacology and Experimental Therapeutics