, 2003). Cltx binds effectively to MMP-2 endogenously expressed by glioma cells ( Deshane et al., 2003 and Veiseh et al., 2007) and exposure results in loss of gelatinase activity, disruption in chloride channel currents, reduction in both MMP-2 and chloride channel expressions, and internalization of chloride channels ( Deshane et al., 2003, McFerrin and Sontheimer, 2006, Soroceanu et al., 1998 and Veiseh et al., 2007). A synthetic version of this peptide (TM601) is being produced by the pharmaceutical industry coupled to iodine 131 (131I-TM601), to carry radiation to tumor cells ( Mamelak and Jacoby, 2007). Pre-clinical studies and phase I clinical trials have been concluded

in patients with recurring glioma. These studies have shown that the intracavitary dose selleck screening library of Selleckchem Bioactive Compound Library 131I-TM601 used was safe, with minimum toxicity, and it bound specifically and effectively to

malignant gliomas for long periods of time. A phase II clinical trial with higher doses of radioactivity and repeated administration of local doses was performed, but the results have not been release yet ( Mamelak et al., 2006 and NIH, 2010). A recent study shows that TM601 inhibited angiogenesis stimulated by pro-angiogenic factors in cancer cells, and when TM601 was co-administered with bevacizumab, the combination was significantly more potent than a ten-fold increase in bevacizumab dose ( Jacoby et al., 2010). Cltx is easily manipulated, binds selectively to glioma cells Dichloromethane dehalogenase and displays low toxicity,

representing a potentially important agent against gliomas. Cltx isolated from the venom of L. quinquestriatus displays amino acid sequence similarity with other animal peptides ( Fig. 1). Among them, there is a 35-amino acid peptide belonging to the family of insectotoxins (ITs), called PBITx1, which was isolated from the venom of the scorpion Parabuthus schlechteri ( Tytgat et al., 1998). ITs belong to a large family of mammalian Na+ channel-selective toxins. Due to the similarities between Cltx and PBITx1, Tytgat et al. (1998) suggest that the new peptide alone could also act specifically on chloride channels ( Fig. 1). Another polypeptide composed of 37 amino acids cross-linked by four disulfide bridges, with high sequence homology to other short toxins such as Cltx, was isolated from the venom of Mesobuthus tamulus and named ButaIT (Buthus tamulus insect toxin) ( Wudayagiri et al., 2001). A recent study shows that ButaIT displays a satisfactory anti-insecticidal activity ( Fitches et al., 2010). There are no studies exploring the possible anti-cancer activity of either ButaIT nor PBITx1; nevertheless, they both show high amino acid sequence homology with Cltx, which might indicate a similar action mechanism upon cancer cells.