Delivery of ribosome-inactivating protein toxin into cancer cells with shock waves.

We report on the use of shock waves delivered by a shock-tube to permeabilize cancer cells and potentiate the cytotoxicity of the type-1 ribosome-inactivating protein, saporin. We studied human colorectal cancer HT29 and ovarian cancer OVCAR-5 cells, and used two different cytotoxicity assays, colony formation and loss of mitochondrial activity. A single shock wave and saporin (10(-9) M) produced significant toxicity not seen with either shock wave or drug alone. Increasing the number of shock waves up to five further increased cytotoxicity. Higher toxicity was seen with the clonogenic assay compared to MTT assay. Shock waves may have applications in promoting cytoplasmic delivery of toxins into cancer cells after intratumoral injection.