Anticancer efficiencies and mechanisms of Pheophorbide-a-mediated photodynamic, sonodynamic and sonophotodynamic therapies were investigated in vitro using androgen-sensitive (LNCaP) and androgen insensitive (PC3) prostate cancer cell lines. The cells were incubated in RPMI-1640 media at various concentrations of Pheophorbide-a. The media was treated with 0.5 W/cm ultrasound and/or 0.5 mJ/cm light irradiation. Cell proliferation in both cell lines was inhibited most effectively by sonophotodynamic therapy in comparison to that of both monotherapies. LNCaP cells were more sensitive to the applied treatments and the cell survival in LNCaP cell line was observed to be less than that of PC3 cell line. The results of histochemical analysis showed that there were more apoptotic cells in the treatment groups in comparison to control group. Additionally, the treatments induced apoptosis deduced by the overexpressed levels of caspase-3, caspase-8, PARP, and Bax proteins, while the expression levels of caspase-9 and Bcl-2 proteins were observed to be lower than those of control group. Treatments led to an increase in the oxidative stress markers, ROS and MDA, but a decrease in the activities of antioxidant enzymes, SOD, CAT and GSH. The results of this study revealed that Pheophorbide a-mediated sonophotodynamic therapy more efficiently activates the apoptotic mechanisms in prostate cancer cells and thus may provide a promising approach for treatment.Copyright © 2020. Published by Elsevier B.V.