Eradication of chemotherapy-resistant CD44+ human ovarian cancer stem cells in mice by intraperitoneal administration of Clostridium perfringens enterotoxin.

Abstract

BACKGROUND:

Emerging evidence has suggested that the capability to sustain tumor formation, growth, and chemotherapy resistance in ovarian as well as other human malignancies exclusively resides in a small proportion of tumor cells termed cancer stem cells. During the characterization of CD44(+) ovarian cancer stem cells, we found a high expression of the genes encoding for claudin-4. Because this tight junction protein is the natural high-affinity receptor for Clostridium perfringens enterotoxin (CPE), we have extensively investigated the sensitivity of ovarian cancer stem cells to CPE treatment in vitro and in vivo.

METHODS:

Real-time polymerase chain reaction and flow cytometry were used to evaluate claudin-3/-4 expression in ovarian cancer stem cells. Small interfering RNA knockdown experiments and MTS assays were used to evaluate CPE-induced cytotoxicity against ovarian cancer stem cell lines in vitro. C.B-17/SCID mice harboring ovarian cancer stem cell xenografts were used to evaluate CPE therapeutic activity in vivo.

RESULTS:

CD44(+) ovarian cancer stem cells expressed claudin-4 gene at significantly higher levels than matched autologous CD44(-) ovarian cancer cells, and regardless of their higher resistance to chemotherapeutic agents died within 1 hour after exposure to 1.0 μg/mL of CPE in vitro. Conversely, small-interfering RNA-mediated knockdown of claudin-3/-4 expression in CD44(+) cancer stem cells significantly protected cancer stem cells from CPE-induced cytotoxicity. Importantly, multiple intraperitoneal administrations of sublethal doses of CPE in mice harboring xenografts of chemotherapy-resistant CD44(+) ovarian cancer stem cells had a significant inhibitory effect on tumor progression leading to the cure and/or long-term survival of all treated animals (ie, 100% reduction in tumor burden in 50% of treated mice; P < .0001).

CONCLUSIONS:

CPE may represent an unconventional, potentially highly effective strategy to eradicate chemotherapy-resistant cancer stem cells.

• Authors: Francesca Casagrande, Emiliano Cocco, Stefania Bellone, Christine E Richter, Marta Bellone, Paola Todeschini, Eric Siegel, Joyce Varughese, Dan Arin-Silasi, Masoud Azodi, Thomas J Rutherford, Sergio Pecorelli, Peter E Schwartz, Alessandro D Santin
• Journal: Cancer (Cancer) Vol. 117 Issue 24 Pg. 5519-28 (Dec 15 2011) ISSN: 1097-0142 [Electronic] United States
• PMID: 21692061 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2011 American Cancer Society.

Chemical References

• CLDN3 protein, human
• Claudin-3
• Claudins
• Cldn3 protein, mouse
• Enterotoxins
• Hyaluronan Receptors
• enterotoxin, Clostridium

Topics

• Adult
• Aged
• Animals
• Carcinoma, Ovarian Epithelial
• Cell Line, Tumor
• Chlorocebus aethiops
• Claudin-3
• Claudins (genetics, metabolism)
• Clostridium perfringens (chemistry, metabolism)
• Enterotoxins (biosynthesis, pharmacokinetics, pharmacology)
• Female
• Flow Cytometry
• Humans
• Hyaluronan Receptors (biosynthesis)
• Injections, Intraperitoneal
• Mice
• Mice, SCID
• Middle Aged
• Neoplasms, Glandular and Epithelial (drug therapy, genetics, metabolism, pathology)
• Neoplastic Stem Cells (drug effects, metabolism)
• Ovarian Neoplasms (drug therapy, genetics, metabolism, pathology)
• Real-Time Polymerase Chain Reaction
• Vero Cells
• Xenograft Model Antitumor Assays