Photodynamic therapy with hexenyl ester of 5-aminolevulinic acid induces necrotic cell death in salivary gland adenocarcinoma cells

Photodynamic therapy has been developed as an alternative therapy of cancer. The aim of this study was to examine whether PDT with hexenyl ester of 5-aminolaevulinic acid (ALA-hx) inhibits the proliferation of the salivary gland adenocarcinoma SGT cells. Cell proliferation was examined by MTT assay. The gene expression of Coproporphyrinogen oxidase (CPO) and ROS production was also examined. Flow cytometry and in vivo Chorioallantoic membrane (CAM) assay was performed. ALA-hx PDT inhibited effectively the proliferation of SGT cells. Treatment of ALA-hx induced CPO mRNA expression and ROS was produced by ALA-hx PDT in SGT cells. Flow cytometry and LDH assay showed that ALA-hx PDT induced necrotic cell death rather than apoptosis in SGT cells. In vivo CAM assay showed that ALA-hx PDT induced tumor destruction by inducing necrosis. These results indicate that ALA-hx PDT effectively inhibits the proliferation of SGT cells by inducing necrosis.