Induction of early apoptosis in human nasopharyngeal carcinoma cells by mTHPC-mediated photocytotoxicity

Christine M.N. Yow*, Nai Ki MAK, Albert W.N. Leung, Zheng Huang

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

18 Citations (Scopus)


Objectives: In this study, the early apoptotic events elicited by mTHPC-mediated photo-cytotoxicity were explored in a human nasopharyngeal carcinoma cell line (NPC/HK1). Methods and materials: NPC/HK1 cells (5 × 103) were incubated with photosensitizer mTHPC (0.8 μg/ml) in chamber slides for 20 h and subjected to light irradiation at 2 J/cm2 (LD80). Morphologic changes of treated cells were examined under light microscopy and confocal microscopy at 0-4 h after the light irradiation. The early stage of apoptosis was detected by fluorescein-conjugated Annexin V (Annexin V-FITC) assay. Mitochondrial membrane damage and cytochrome c release were determined by flowcytometric analysis. Bcl-2 expression was measured by Western blot analysis. Results: One hour after mTHPC-mediated photodynamic therapy (PDT), microscopic examination showed membrane blebbing and cell shrinkage. Annexin V-FITC assay showed that a considerable number of NPC/HK1 cells became apoptotic. Flowcytometric analysis showed that the cytochrome c was released at 1 h after PDT. Bcl-2 expression also declined significantly compared to control groups. Conclusions: mTHPC-mediated photo-cytotoxicity can effectively induce early apoptotic responses in NPC/HK1 cells which might be modulated by mitochondrial damages and Bcl-2 inhibition.

Original languageEnglish
Pages (from-to)122-127
Number of pages6
JournalPhotodiagnosis and Photodynamic Therapy
Issue number2
Publication statusPublished - Jun 2009

Scopus Subject Areas

  • Biophysics
  • Oncology
  • Dermatology
  • Pharmacology (medical)

User-Defined Keywords

  • Apoptosis
  • mTHPC
  • Nasopharyngeal carcinoma
  • PDT
  • Phototoxicity


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