Cell death mechanisms vary with photodynamic therapy dose and photosensitizer

Jin He; Nancy L. Oleinick

doi:10.1117/12.203431

1 March 1995 Cell death mechanisms vary with photodynamic therapy dose and photosensitizer

Jin He, Nancy L. Oleinick

Author Affiliations +

Proceedings Volume 2371, 5th International Photodynamic Association Biennial Meeting; (1995) https://doi.org/10.1117/12.203431
Event: Fifth International Photodynamic Association Biennial Meeting, 1994, Amelia Island, FL, United States

Abstract

Mouse lymphoma L5178Y-R cells respond to photodynamic therapy (PDT) by undergoing rapid apoptosis, which is induced by PDT-activated signal transduction initiating in the damaged cellular membranes. To relate the level of PDT damage and photosensitizer to the mechanism of cell death, apoptosis has been detected by agarose gel electrophoresis of fragmented DNA and quantified by flow cytometry of cells after staining with Hoechst33342 and propidium iodide, a technique which can distinguish between live, apoptotic, and necrotic cells. When the silicon phthalocyanine Pc 4 or Pc 12 served as photosensitizer, lethal doses (as defined by clonogenic assay) of PDT induced apoptosis in essentially all cells, whereas supralethal doses prevented the characteristic degradation of DNA into oligonucleosomal fragments. In contrast with aluminum phthalocyanine (AlPc) cells died by apoptosis after all doses studied. It appears that high PDT doses with Pc 4 or Pc 12 damage enzymes needed to carry out the program of apoptosis; the absence of this effect with AlPc suggests either a different intracellular location or different photocytotoxic mechanism for the two photosensitizers.

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Jin He and Nancy L. Oleinick "Cell death mechanisms vary with photodynamic therapy dose and photosensitizer", Proc. SPIE 2371, 5th International Photodynamic Association Biennial Meeting, (1 March 1995); https://doi.org/10.1117/12.203431

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