Korean J Otolaryngol-Head Neck Surg.  2006 Dec;49(12):1194-1200.

ROS Formation and the Mechanism of Photodynamic Therapy Using 9-Hydroxypheophorbide-a on AMC-HN3 Human Head and Neck Carcinoma Cell Line

• Chung PS
• Park E
• Lee KI
• Ahn JC

Abstract

BACKGROUND AND OBJECTIVES
During PDT, photosensitizer accumulates in the cell and irradiation forms ROS. ROS leads to activation of apoptoticpathway and cell death. Elevated intracellular calcium is known to play important role in apoptotic pathway. There are two type of ROS formation. The type of ROS formation differs in type of photosensitizers. We designed the experiment to define the relationship of ROS and cell death in PDT. MATERIALS AND METHOD: AMC-HN3 cells were cultured. Using a CaspACE assay kit, we measured caspases-3 activity after PDT. We also observed intra-cellular calcium concentrations using confocal microscopy (calcium green-1 stain) after PDT. To determine which type of reaction occursduring ROS formation, MTT assay was performed.
RESULTS
Confocal microscopy showed that ROS had formed at the site of photosensitizer formation after PDT. After PDT, intracellular calcium increased. MTT assay showed more viability increase in blocking type II reaction. Caspase assay showed highest level after 4hrs.
CONCLUSION
ROS is formed at the site photosentizer formation after PDT. Type II reaction was the main type of ROS formation. Apoptosis was main pathway of cell death in low dose of photosensitizer after PDT.

Keyword

Photodynamic therapy (PDT); Reactive oxygen species (ROS); 9-Hydroxypheophorbide-a

MeSH Terms

Apoptosis
Calcium
Cell Death
Cell Line*
Head*
Humans*
Microscopy, Confocal
Neck*
Photochemotherapy*
Photosensitizing Agents
Calcium
Photosensitizing Agents