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Research Paper
BAM-SiPc, a Novel Agent for Photodynamic Therapy, Induces Apoptosis in Human Hepatocarcinoma HepG2 Cells by a Direct Mitochondrial Action
Janice C. Lai, Pui-Chi Lo, Dennis K.P. Ng, Wing-Hung Ko, Stanley C.H. Leung, Kwok-Pui Fung and Wing-Ping Fong
volume 5 | issue 4
april 2006Pages: 413-418
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Photodynamic therapy is recently developed as an effective treatment for malignant disease. The therapeutic effect depends on the properties of the photosensitizers. Among the novel photosensitizers we have synthesized, the unsymmetrical bisamino phthalocyanine, SiPc[C3H5(NMe2)2O](OMe) [abbreviated as BAM-SiPc] is particularly active in the HepG2 cell culture model. Fluorescence microscopy has also indicated that it targets the mitochondria. In the present investigation, the biochemical mechanisms of BAM-SiPc leading to cell death were investigated. Photodynamic treatment with BAM-SiPc resulted in the generation of reactive oxygen species and a collapse of mitochondrial membrane potential. The pro-apoptotic Bax protein was translocated from the cytosol to mitochondria; while the level of the mitochondrial anti-apoptotic Bcl-2 protein decreased after photodynamic treatment. Cytochrome c, but not apoptosis-inducing factor, was released from the mitochondria into the cytosol, subsequently resulting in the cleavage of poly(ADP-ribose) polymerase. These events were at least partially responsible for the observed BAM-SiPc induced apoptosis, which was clearly demonstrated by (a) the loss of membrane asymmetry, (b) DNA ladder formation, and (c) the presence of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells.
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
Download PDFIf the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.