Anti-gliomas Effect of Chlorotoxin-Conjugated Onconase at High Dose.

Malignant gliomas are rarely curable malignant tumors in the central nervous system. Chlorotoxin (CTX) is a peptide derived from scorpion venom, which can selectively target malignant gliomas. Onconase (Onc) is a small cytotoxic ribonuclease derived from frogspawn that exhibits cytotoxicity against some tumor cells. In the present study, we found that CTX-conjugated Onc (CTX-Onc) shows better anti-tumor effect than the physical mixture of CTX and Onc (CTX + Onc) on the nude mice carrying subcutaneous glioblastoma cell-derived tumor. However, CTX-Onc does not show dose-dependent anti-tumor effect. In addition, apoptosis in tumor tissue does not show significant difference between the treatment groups. Our results confirmed that CTX-Onc has better anti-tumor effect than CTX + Onc and suggest that it can be potentially used for glioma therapy.