Photodynamic effects in vitro in fresh gynecologic tumors analyzed with a bioluminescence method

Photodynamic therapy (PDT) is a promising alternative method for clinical c ancer treatment. In the present study, cells from four breast carcinomas, s even ovarian carcinomas of various stages of differentiation, and ascites f rom a diffuse metastatic tumor were treated by PDT in vitro. Tetra(m-hydrox yphenyl)chlorin (m-THPC) was used as the photosensitizer. Surviving cell ra te was evaluated by the ATP-Cell-Viability-assay (ATP-CVA), which measures light production as an interaction of intracellular ATP with the luciferin- luciferase complex. The most effective PDT of the tumor cells was achieved at an m-THPC concentration of 0.2 mu g/ml following incubation of the cells with photosensitizer for 24 hours. PDT toxicity resulted in a cell surviva l rate of 1 % to 42 % compared to untreated control cells (survival rate of control = 100 %). The inhibitor concentration IC50 of m-THPC was determine d both in the dark (dark toxicity) and in combination with laser irradiatio n. IC50 was defined as the concentration of photosensitizer which caused 50 % of cell death. The IC50 values were heterogeneous in all tumor specimens examined. IC50 values for dark toxicity were on average 0.14 mu g m-THPC/m l for primary ovarian carcinoma, 2.16 mu g m-THPC mi for refractory ovarian carcinoma and 0.3 mu g m-THPC/ml for breast carcinoma. After PDT, average IC50 value for refractory ovarian carcinoma was 0.04 mu g m-THPC/ml, for pr imary ovarian carcinoma 0.05 mu g m-THPC/ml and for breast carcinoma 0.03 m u g m-THPC/ml. These data might indicate that clinical PDT of gynecological carcinoma requires individual treatment conditions to achieve optimal resu lts.