title: Photodynamic therapy (PDT) - Initiation of apoptosis via activation of stress-activated p38 MAPK and JNK signal pathway in H460 cell lines.
abstract: OBJECTIVE
  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).
  
  
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Health Technology & Informatics, The Hong Kong Polytechnic University, Hong Kong.
authors.forename: R W K
authors.initials: RW
authors.lastname: Wu
authors.forename: C M N
authors.initials: CM
authors.lastname: Yow
authors.forename: C K
authors.initials: CK
authors.lastname: Wong
authors.forename: Y H
authors.initials: YH
authors.lastname: Lam
mesh_terms: D000622:Aminolevulinic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000201:enzymology* / Q000473:pathology; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D004396:Coloring Agents; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D006801:Humans; D007211:Indoles; D048031:JNK Mitogen-Activated Protein Kinases / Q000187:drug effects; D008175:Lung Neoplasms / Q000201:enzymology* / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011355:Prodrugs / Q000494:pharmacology; D011524:Protoporphyrins / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013778:Tetrazolium Salts; D013844:Thiazoles; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects*
chemical_list: D004396:Coloring Agents; D005456:Fluorescent Dyes; D007211:Indoles; D017319:Photosensitizing Agents; D011355:Prodrugs; D011524:Protoporphyrins; D013778:Tetrazolium Salts; D013844:Thiazoles; C007293:DAPI; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C022616:thiazolyl blue; C419924:5-aminolevulinic acid hexyl ester