Studies of the effects of associated photodynamic therapy and drugs on macromolecular synthesis of tumoral cells grown in vitro.

Abstract

HeLa S3 tumoral cells were used as an experimental model for studying the association of photodynamic therapy (PDT) and antitumoral agents. Tumoral monolayer cultures were incubated 18 hours at 37 degrees C with Photofrin II, trypsinized and suspended in Eagle medium supplemented with 10% FCS and then treated with antitumoral agents 90 minutes before He-Ne laser exposure. The tumoral cells were exposed to antitumoral agents in the following concentrations (equivalent to ED70): adriamycin (0.0297 micrograms); mitomycin C (0.0199 micrograms); 5-FU (0.4937 micrograms) and vinblastine (0.0109 micrograms) per 10(5) cells. Macromolecular syntheses (DNA, RNA and proteins) were investigated by use of radioactive precursors: 3H-thymidine, 3H-uridine and 3H-leucine, as expressed in percent referring to Photofrin II-pretreated controls; they were exposed to He-Ne laser but not treated with antitumoral agents. All experiments were followed for 72 hours incubation at 37 degrees C. The conclusions of the results of PDT associated with antitumoral agents sustain the following aspects: a) the antitumoral agents activity (adriamycin, mitomycin C, 5-FU, vinblastine) was more noticeable when applied 90 minutes before He-Ne laser irradiation; b) inhibition of radioactive precursors uptake in DNA, RNA and proteins was accompanied by suppression of in vitro tumoral cells development and c) PDT association with antitumoral agents could manifest at least three positive effects upon animals; 1) PDT potentiating effects with antitumoral agents; 2) suppressing effects on tumoral macromolecular synthesis; 3) antitumoral agents cytotoxic elimination (due to the low doses used).