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

Autor: Alessandro D. Santin, Masoud Azodi, Marta Bellone, Stefania Bellone, Joyce Varughese, Dan Arin-Silasi, Eric R. Siegel, Francesca Casagrande, Peter E. Schwartz, Sergio Pecorelli, Thomas J. Rutherford, Christine E. Richter, Paola Todeschini, Emiliano Cocco
Jazyk: angličtina
Rok vydání: 2011
Předmět:
Popis: Epithelial ovarian carcinoma (EOC) remains the cancer with the highest mortality rate among gynecological tumors.1 At the time of diagnosis, ⅔ of patients have advanced disease, and unfortunately, after their initial response to the combination of surgery and platinum-based chemotherapy, the majority of ovarian cancer patients develop recurrence and inevitably die from the development of chemotherapy-resistant disease.2 Thus, the identification of novel therapeutic strategies against chemotherapy-resistant/recurrent ovarian cancer remains a high priority. Emerging evidence has recently been provided to suggest 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 or tumor-initiating cells.3–6 The stem cell-like phenotype of tumor-initiating cells and their limited number within the bulk of the tumor may lead to disease relapse, although the primary lesion is eradicated by conventional therapies; hence, the identification and characterization of tumor stem cells remains of paramount importance for the development of therapeutic strategies capable of affecting the survival of tumor-initiating as well as nontu-morigenic cells. In an attempt to unravel the mechanisms for repair and chemotherapy resistance of these highly lethal gynecologic tumors, several research groups have recently described the identification and characterization of the molecular phenotype of human ovarian cancer stem cells.7–10 In a large number of studies, CD44 has been extensively reported as a marker that can enrich for cancer stem cells in multiple solid tumors, and its specific correlation with ovarian cancer stem cells has been consistently established.7–10 Accordingly, in this study, cancer stem cells were isolated from ascites and solid tumors of multiple ovarian cancer patients and characterized as CD44+/MyD88+ cells showing constitutive nuclear factor κ B (NF-KB) activity, cytokine and chemokine production, high capacity for repair, resistance to conventional chemotherapies, resistance to tumor necrosis factor α-mediated apoptosis, capacity to form spheroids in suspension, and more importantly, ability to recapitulate in vivo the original tumor. Of great interest, we found CD44+ ovarian cancer stem cells to express high levels of the gene encoding the tight junction protein claudin-4. Because this protein has been shown to represent the high-affinity natural receptor for Clostridium perfringens enterotoxin (CPE), and is capable of mediating CPE binding and cytolysis,11,12 in this study, we have: 1) carefully analyzed and quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and flow cytometry the expression levels of claudin-3/-4 receptors in CD44+ cancer stem cell populations derived from multiple freshly explanted ovarian tumors, 2) tested the ability of CPE to kill chemotherapy-resistant ovarian CD44+ cancer stem cells overexpressing claudin-4 in vitro, 3) investigated in functional assays the effects of claudin-3/-4 receptors knockdown on CPE-induced CD44+ cancer stem cell toxicity in vitro, and 4) studied the in vivo efficacy and toxicity of intraperitoneal (i.p.) CPE therapy in SCID mice harboring xenografts of highly relevant clinical models of chemotherapy-resistant freshly explanted ovarian CD44+ cancer stem cells. We report for the first time that ovarian CD44+ cancer stem cells overexpress the high-affinity claudin-4 CPE receptor and that these chemotherapy-resistant cells are highly sensitive to CPE treatment in vitro. More importantly, we report that in vivo therapy with repeated i.p. injections of well-tolerated doses of CPE induces the cure or long-term survival of animals harboring established chemotherapy-resistant ovarian CD44+ cancer stem cell-initiated tumors. CPE-mediated therapy may thus represent a novel, potentially highly effective strategy for the eradication of ovarian CD44+ cancer stem cells resistant to chemotherapy.
Databáze: OpenAIRE
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