Combination with genistein enhances the efficacy of photodynamic therapy against human anaplastic thyroid cancer cells

Abstract

Photodynamic therapy (PDT) has become one of the emerging options in management of cancer and other diseases. The major goal of PDT is to kill cancer cell without causing any adverse effect to the normal cells. PDT in combination of different therapeutic agents is being evaluated to improve the efficacy of treatment. Genistein, a soy ingredient, has widely been studied against different types of cancer. In the present study, combination of these two therapeutic methods has been studied to evaluate the enhanced effectiveness and find out the mechanism of action. Combination of PDT and genistein has been studied against human thyroid cancer cells SNU 80. Cells were treated with genistein and different concentration of photofrin in PDT singly and conjointly. Viability of SNU 80 cells was analyzed using MTT assay. The cells were stained with Hoechst 33342 and propidium iodide (PI) for morphological observations. Changes in mitochondrial membrane potential and generation of reactive oxygen species (ROS) were also studied by confocal microscopy. Western blot analysis were also performed to find out the expressions of different pro- and anti-apoptotic proteins. From the result, the combination of genistein and photofrin mediated PDT enhanced the apoptotic effect against SNU 80 cells. Proliferation of the cells was inhibited and the mitochondrial membrane depolarisation was observed. ROS level were also increased in combination treatment. The expressions of Caspase 3, Caspase 9, cytochrome c, Caspase 8, Caspae 12 and other apoptosis related proteins were also modified. Thus PDT can induce apoptosis in thyroid cancer cells singly or in combination with genistein. But in combination treatment, the efficacy of inducing apoptosis in SNU 80 cells is much higher than that of individual treatment with genistein or PDT.