Effects of electrochemotherapy on CaSki cells derived from a cervical squamous cell carcinoma

Electrochemotherapy is a new approach to the treatment of tumors that takes advantage of the permeabilization of the cell membranes by electric pulses to facilitate the intracellular delivery of chemotherapeutic drugs into cells. Using the female genital squamous cell carcinoma cell line, CaSki, the antitumor effectiveness of electrochemotherapy was tested. In vitro studies showed that the cytotoxicity of some anticancer drugs, especially bleomycin, can be greatly enhanced by exposing cells to noncytotoxic electric pulses. This enhancement was significantly greater when the electric treatment was given after exposure to the drug than when applied preexposure. Treatment of nude mice bearing subcutaneous transplanted tumors with noneffective intraperitoneal doses of bleomycin followed by local delivery of electric pulses similar to those performed in vitro resulted in tumor reduction and complete disappearance after 12 days this electrochemotherapy. Histological changes in tumor tissue such as necrosis and degeneration were extensive even 6 hr after the electrochemotherapy. Thus the antitumor effects of bleomycin in mice can be considerably potentiated by local electric pulses, suggesting that electrochemotherapy with bleomycin may have promise for treatment of vulvar or ectocervical squamous cell carcinomas with early invasion.