title: Role of mitogen-activated protein kinase in Zn-BC-AM PDT-induced apoptosis in nasopharyngeal carcinoma cells.
abstract: Photodynamic therapy (PDT) with a recently developed photosensitizer Zn-BC-AM was found to effectively induce apoptosis in a well-differentiated nasopharyngeal carcinoma (NPC) HK-1 cell line. Sustained activation of p38 mitogen-activated protein kinase (MAPK) and c-jun N-terminal kinase (JNK) as well as a transient increase in activation of extracellular signal-regulated kinase (ERK) were observed immediately after Zn-BC-AM PDT. A commonly used p38 MAPK/JNK pharmacological inhibitor PD169316 was found to reduce PDT-induced apoptosis of HK-1 cells. PD169316 also prevented the loss of Bcl-2 and Bcl-xL in PDT-treated HK-1 cells. However, inhibition of JNK with SP600125 had no effect on Zn-BC-AM PDT-induced apoptosis while inhibition of ERK with PD98059 or p38 MAPK with SB203580 significantly increased Zn-BC-AM PDT-induced apoptosis. Further study showed that knockdown of the p38beta isoform with siRNA also increased Zn-BC-AM PDT-induced apoptosis, indicating that the anti-apoptotic effect of PD169316 in PDT-treated HK-1 cells was probably independent of p38 MAPK or JNK activation. Taken together, the results suggest that inhibition of p38beta and ERK may enhance the therapeutic efficacy of Zn-BC-AM PDT on NPC cells. It should be noted that data only based on the use of PD169316 should be interpreted in caution.
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong.
authors.forename: H K
authors.initials: HK
authors.lastname: Koon
authors.forename: P S
authors.initials: PS
authors.lastname: Chan
authors.forename: Z G
authors.initials: ZG
authors.lastname: Wu
authors.forename: R N S
authors.initials: RN
authors.lastname: Wong
authors.forename: M L
authors.initials: ML
authors.lastname: Lung
authors.forename: C K
authors.initials: CK
authors.lastname: Chang
authors.forename: N K
authors.initials: NK
authors.lastname: Mak
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008665:Metalloporphyrins / Q000494:pharmacology*; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D008665:Metalloporphyrins; D017319:Photosensitizing Agents; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; C497948:Zn-BC-AM; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases