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Hypericin‐PDT‐induced rapid necrotic death in human squamous cell carcinoma cultures after multiple treatment
Author(s) -
Sharma Krishna V.,
Davids Lester M.
Publication year - 2012
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1042/cbi20120108
Subject(s) - hypericin , photodynamic therapy , programmed cell death , apoptosis , photosensitizer , cancer research , reactive oxygen species , viability assay , cell , chemistry , microbiology and biotechnology , biology , pharmacology , biochemistry , photochemistry , organic chemistry
PDT (photodynamic therapy) has been used for the treatment of NMCC (non‐melanoma cutaneous cancer) particularly, human SCC (squamous cell carcinoma). However, the nature of the photosensitizer, the activation light source and the mode of cell death induced post‐PDT remains elusive. We tried to optimize PDT using the light‐activated (320–400 nm) St John's Wort‐derived compound, Hyp (hypericin). The work highlights the potential mode of cell death and the increased efficacy of the technique associated with multiple Hyp‐PDT treatment. SCC cells were exposed to different concentrations of Hyp and activated with light at 1 J/cm 2 for 1 or 2 days. Thereafter with the optimum dose of Hyp proliferation, ROS (reactive oxygen species), and apoptosis were analysed by XTT [2,3‐bis‐(2‐methoxy‐4‐nitro‐5‐sulfophenyl)‐2 H ‐tetrazolium‐5‐carboxanilide] assay, FACS analysis and Fluorescent/Phase contrast microscopy was carried out for morphological studies. Hyp‐PDT produces more ROS after 1 day compared with 2 days and the mode of cell death is a necrotic caspase‐independent mechanism. We propose a novel ‘double‐hit/2‐day’ strategy to reduce the viability in SCC using Hyp‐based PDT as an adjunctive treatment modality.