Insulin potentiation of photodynamic activity in vitro

Abstract

The present work reports on the investigation of the possible influence of insulin on the photodynamic effect of the photosensitizer radachlorin on four cell lines: HepG2, HT-29, BJ and BALB/3T3. For a quantitative comparison, the insulin effect on the standard chemotherapy drug methotrexate is also measured. The results show that the EC[Formula: see text] value for methotrexate is 40% higher than when combined with insulin; and for the lowest methotrexate concentration used, the difference exceeds 120%. For the case of the photodynamic effect, it is shown that insulin, when applied in combination with radachlorin, improves the cell permeability for the photosensitizer, thus increasing its concentration in the cells. The cytotoxic effect of photodynamic therapy with radachlorin as the photosensitizer has been quantitatively compared. The quantitative comparison of the photodynamic effect in the cases of using the photosensitizer radachlorin both alone and in combination with insulin, shows that the addition of insulin does not have an effect on the model of normal cell lines used; while for the HepG2 tumor cells, a two-fold increase in the EC[Formula: see text] value is measured.