Anticancer Photosensitizer Induce Tumor Cells Apoptosis Via Mitochondrion Signal Transduction Pathway

Objective: To investigate the antitumor activity of a series of metal phthalocyaninezinc, the present study focused on exploring the mechanisms of action of the leadphotosensitizer, namely PHOTOCYANINE, on hepatocellular carcinoma (HCC)HepG2cells to guide our future development of metal phthalocyanines.Methods: The effect of phthalocyanine content zinc compounds on the viability ofcancer cell lines including human hepato carcinoma cell HepG2, human gastriccarcinoma cell BGC-823and AGS, human neuroblastoma cell SH-SY5Y, humanembryonic lung fibroblast cell HELF and human gastric epithelium cell GES-1wasinvestigated using MTT assay. PHOTOCYANINE-induced morphological changeswere assessed by light microscope and fluorescence microscope after DAPI staining.In particular, PHOTOCYANINE-induced apoptosis was detected by AO/EB andAnnexin V-Fluos staining, and DNA cell cycle was detected by propidium iodide (PI)analysis. Using mitochondrial, lososome and endoplasmic reticulum probe staining,the subcellular localization of PHOTOCYANINE in HepG2cells was detected bylaser confocal microscope. The effect of PHOTOCYANINE via the mitochondrialsignaling pathway was studied using reactive oxygen, mitochondrial membranepotential (ΔΨm) and the Caspase-3, Caspase-8and Caspase-9assay kit.Results: The data of MTT revealed that in the four Zinc phthalocyanine compoundZnPc，PHOTOCYANINE，ZnPcS3P1and ZnPcS4，ZnPc and PHOTOCYANINE hadsignificant antiproliferative ability to above four cancer cells while low cytotoxic toGES-1and HELF. Apoptosis morphological changes about chromatic agglutinationand nuclear condensation were detected by light microscope and fluorescencemicroscope with AO/EB and DAPI staining after treatment with differentconcentration of PHOTOCYANINE. Using Annexin V-FLUOS/PI double markers, theflow cytometric analysis found that the apoptotic and necrosis cells in treatment group were significantly more than those in control group when the dose ofPHOTOCYANINE increased. PI analysis revealed that cell cycle was mainly arrestedat G2/M stage. Using organelles fluorescent probe staining, the laser scanningconfocal microscope analysis found that amphipathic PHOTOCYANINE permeatedthrough cell membrane and predominately distributed in lysosome, mitochondria andendoplasmic reticulum. After treated by PHOTOCYANINE, the mitochondrialmembrane potential (ΔΨm) reduced. The production of reactive oxygen species(ROS), the activity of Caspase-3and Caspase-9were significant increase，while theincrease of Caspase-8was not obvious.Conclusion: PHOTOCYANINE is a high effective and low toxic photosensitizer, andinduces HepG2cell lines apoptosis via acting on mitochondrial membrane to reduceΔΨm, producing ROS and activating Caspase-9and Caspase-3. Furthermore, it causescell arrest at G2/M stage.