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

• Published in: Photodiagnosis and photodynamic therapy 2011-09, Vol.8 (3), p.254-263
• Main Authors: Wu, R.W.K, Yow, C.M.N., PhD, Wong, C.K, Lam, Y.H
• Format: Article
• Language: English
• Subjects: 5-Aminolevulinic acid; Aminolevulinic Acid - analogs & derivatives; Aminolevulinic Acid - pharmacology; Apoptosis; Apoptosis - drug effects; Bcl-2; Blotting, Western; Carcinoma, Non-Small-Cell Lung - enzymology; Carcinoma, Non-Small-Cell Lung - pathology; Cell Death - drug effects; Cell Line, Tumor; Coloring Agents; Enzyme Activation - drug effects; Extracellular Signal-Regulated MAP Kinases - drug effects; Flow Cytometry; Fluorescent Dyes; Hematology, Oncology and Palliative Medicine; Humans; Indoles; Internal Medicine; JNK Mitogen-Activated Protein Kinases - drug effects; Lung carcinoma; Lung Neoplasms - enzymology; Lung Neoplasms - pathology; MAP Kinase Signaling System - drug effects; p38 Mitogen-Activated Protein Kinases - drug effects; Photochemotherapy - methods; Photodynamic therapy; Photosensitizing Agents - pharmacology; Prodrugs - pharmacology; Protoporphyrin IX; Protoporphyrins - pharmacology; Signal Transduction - drug effects; Tetrazolium Salts; Thiazoles; Up-Regulation
• ISSN: 1572-1000; 1873-1597
• DOI: 10.1016/j.pdpdt.2010.12.002

Summary 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 (5 μM) uptake revealed optimal fluorescent intensity at 8 h incubation, while ALA (0.5 mM) was still far from saturation. The LD30 of H-ALA-PDT was 30 μM, 2 J/cm2 , while the LD30 of ALA-PDT was 3 mM, 2 J/cm2 . 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.