A Claudin-Targeting Molecule as an Inhibitor of Tumor Metastasis

Abstract

Tumor metastasis of epithelium-derived tumors is the major cause of death from malignant tumors. Overexpression of claudin is observed frequently in malignant tumors. However, claudin-targeting antimetastasis therapy has never been investigated. We previously prepared a claudin-4-targeting antitumor molecule that consisted of the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) fused to protein synthesis inhibitory factor (PSIF) derived from Pseudomonas exotoxin. In the present study, we investigated whether claudin CPE receptors can be a target for tumor metastasis by using the C-CPE-fused PSIF as a claudintargeting agent. One of the most popular murine metastasis models is the lung metastasis of intravenously injected B16 cells. Therefore, we first investigated the effects of the C-CPE-fused PSIF on lung metastasis of claudin-4-expressing B16 (CL4-B16) cells. Intravenous administration of the C-CPE-fused PSIF suppressed lung metastasis of CL4-B16 cells but not B16 cells. Injection of C-CPE-fused PSIF also inhibited tumor growth and spontaneous lung metastasis of murine breast cancer 4T1 cells inoculated into the subcutis. Treatment with C-CPE-fused PSIF did not show apparent side effects in mice. These findings indicate that claudin targeting may be a novel strategy for inhibiting some tumor metastases.

Novel Clostridium perfringens enterotoxin suicide gene therapy for selective treatment of claudin-3- and -4-overexpressing tumors

“…Here, particularly the claudin-specific binding property of the CPE C-terminal domain was employed to target other toxins, such as diphteria toxin fragment A (DT-A), Pseudomonas aeroginosa exotoxin (PE) or TNF-a. [39][40][41][42][43] These approaches exploit CPE-mediated targeting to introduce the toxic proteins into tumor cells, and were shown to be effective in vitro and in vivo. These strategies aimed rather at improvement of cytotoxicities of DT-A, PE or TNF-a, than the toxicity of CPE itself.…”

“…However, in vivo frequent applications of CPE and of CPE-fusion proteins were required to achieve therapeutic effects. [39][40][41]43 In contrast, CPE as a sole full-length protein combines both strong target specificity and very efficient cytotoxicity, which is important for in vivo applications to achieve rapid tumor destruction. This study demonstrated that although CPE is produced inside the transfected cells, its outside action for pore formation and cell lysis is not hampered.…”

Claudin-3 and Claudin-4 Regulate Sensitivity to Cisplatin by Controlling Expression of the Copper and Cisplatin Influx Transporter CTR1

“…What role these proteins serve in ovarian cancers is largely unknown, and data from studies addressing this question have yielded conflicting results (reviewed in Hewitt et al, 2006;Kominsky, 2006;Ouban and Ahmed, 2010). CLDN3 and CLDN4 are of particular interest in ovarian cancer therapy because CLDN3 and CLDN4 are the only transmembrane tissue-specific claudins capable of mediating Clostridium perfringens enterotoxin binding and cytolysis (Katahira et al, 1997); therefore, they have attracted attention as potential therapeutic targets (Morin, 2005;Kominsky, 2006;Kominsky et al, 2007;Yuan et al, 2009;Saeki et al, 2010). We made the novel observation that CLDN3 and CLDN4 modulate sensitivity to the cytotoxic effect of cDDP.…”

Recent Advances in Claudin-Targeting Technology

“…In addition, c-cPE-PSIF did not lead to decreases of body weight and to any apparent biochemical side effects in treated mice. 26) Together, these findings indicate that CL-targeting therapy may be a potent antitumor strategy.…”

“…We inoculated mice with 4T1 cells, a murine cell line frequently used as a spontaneous lung metastasis model, 26) then treated the mice with c-cPE-PSIF. c-cPE-PSIF significantly suppressed tumor growth ( Fig.…”