Photodynamic therapy (PDT) – Initiation of apoptosis via activation of stress-activated p38 MAPK and JNK signal pathway in H460 cell lines

Aims: The purpose of this study was to investigate the photoefficacies of protoporphyrin IX (PpIX) generated by drug precursor 5-aminolevulinic acid (ALA) and its hexyl ester (H-ALA) on two human non-small lung carcinoma cell lines (H460/Bcl-2 and H460/neo). Main methods: Drug uptake and the photoefficacies of PpIX were measured by flow cytometry and MTT assay; while the mode of cell death and alternation of signal transduction pathways were studied with 4',6-diamidino-2-phenylindole (DAPI) staining and Western blot analysis, respectively. Key findings: The flow cytometric analysis of H-ALA (5μM) uptake revealed optimal fluorescent intensity at 8h incubation, while ALA (0.5mM) was still far from saturation. The LD 30 of H-ALA-PDT was 30μM, 2J/cm 2, while the LD 30 of ALA-PDT was 3mM, 2J/cm 2. The dark toxicities mediated by both pro-drug H-ALA and ALA were negligible. By DAPI staining, apoptotic cell death was observed. In addition, by Western blot analysis, H-ALA- and ALA-mediated PDT initiated apoptotic cell death via the up-regulation and activation of p38 mitogen activated protein kinase (MAPK), the stress-activated c-jun N-terminal kinases (JNK) and ERK. Significance: These results suggested that H-ALA and ALA mediated PDT displayed similar photocytotoxicities towards the two non-small lung cancer cells. Our present study also demonstrates H-ALA or ALA mediated PDT in H460 cells are closely related to the activation of p38 MAPK and JNK signalling pathway.Department of Health Technology and Informatic

Cellular uptake, subcellular localization and photodamaging effect of Temoporfin (mTHPC) in nasopharyngeal carcinoma cells: comparison with hematoporphyrin derivative

Temoporfin (meta-tetra (hydroxyphenyl)chlorin; mTHPC) potentiated a 100-fold higher cytotoxic effect than hematoporphyrin derivative (HPD) on two nasopharyngeal carcinoma cell lines (HK1 and CNE2) in terms of the overall photodynamic therapy (PDT) dose. The cellular uptake, evaluated by flow cytometry and spectrophotometry demonstrated that mTHPC exhibited higher uptake ability than HPD. Confocal laser scanning microscopy detection for both the sensitizer and mitochondria probe on the same cell images revealed that both drugs accumulated diffusely in the cytoplasm and that mitochrondria is a target organelle. Photo-activation ruptured the mitochrondria, with more pronounced mitochondrial damage being observed in mTHPC-PDT course. This correlated well with the cell photokilling efficiency of mTHPC.School of Nursin