Evaluation of Silicon Phthalocyanine 4 Photodynamic Therapy against Human Cervical Cancer Cells in Vitro and in Mice

Abstract

Background: Cervical cancer is the second most common cancer in women world-wide [1]. Photodynamic therapy has been used for cervical intraepithelial neoplasia with good responses, but few studies have used newer phototherapeutics. We eva-luated the effectiveness of photodynamic therapy using Pc 4 in vitro and in vivo against human cervical cancer cells. Methods: CaSki and ME-180 cancer cells were grown as monolayers and spheroids. Cell growth and cytotoxicity were measured using a methylthiazol tetrazolium assay. Pc 4 cellular uptake and intracellular distri-bution were determined. For in vitro Pc 4 photodynamic therapy, cells were irra-diated at 667 nm at a fluence of 2.5 J/cm 2 at 48 h. SCID mice were implanted with CaSki and ME-180 cells both subcutaneously and intracervically. Forty-eight hours after Pc 4 photodynamic therapy was administered at 75 and 150 J/cm 2 . Results: The IC 50 s for Pc 4 and Pc 4 photodynamic therapy for CaSki and ME-180 cells as mono-layers were, 7.6 µM and 0.016 µM and >10 µM and 0.026 µM; as spheroids, IC 50 s of Pc 4 photodynamic therapy were, 0.26 µM and 0.01 µM. Pc 4 was taken up within cells and widely distributed in tumors and tissues. Intracervical photodynamic ther-apy resulted in tumor death, however mice died due to gastrointestinal toxicity. Photodynamic therapy resulted in subcutaneous tumor death and growth delay.