Peptide-based therapy against cancer is a field of great interest for biomedical developments. Since it was shown that SK3 channels promote cancer cell migration and metastatic development, we started using these channels as targets for the development of antimetastatic drugs. Particularly, tamapin (a peptide found in the venom of the scorpion Mesobuthus tamulus) is the most specific toxin against the SK2 channel currently known. Considering this fact, we designed diverse tamapin mutants based on three different hypotheses to discover a new potent molecule to block SK3 channels. We performed in vitro studies to evaluate this new toxin derivative inhibitor of cancer cell migration. Our results can be used to generate a new tamapin-based therapy against cancer cells that express SK3 channels.

The need for molecules with high specificity against noxious insects leads the search towards spider venoms that have evolved highly selective toxins for insect preys. In this respect, spiders as a highly diversified group of almost exclusive insect predators appear to possess infinite potential for the discovery of novel insect-selective toxins. In 2003, a group of toxins was isolated from the spider Macrothele gigas and the amino acid sequence was reported. We obtained, by molecular biology techniques in a heterologous system, one of these toxins. Purification process was optimized by chromatographic methods to determine the three-dimensional structure by nuclear magnetic resonance in solution, and, finally, their biological activity was tested. rMagi3 resulted to be a specific insect toxin with no effect on mice.

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