• ALA;
  • apoptosis;
  • HepG2;
  • p53;
  • photodynamic therapy;
  • PpIX


Objectives: To examine the efficacy and mechanism of δ- or 5-aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) on a human hepatocellular carcinoma cell line.

Materials and methods: The optimal uptake of photosensitizer ALA in HepG2 (p53 wild) cells was investigated by means of spectrometric measurement. Cell viability was determined by trypan blue exclusion assay. Morphological apoptotic changes in HepG2 cells before and after ALA-mediated PDT were determined by microscopic examination. Detection of apoptotic bodies was examined by DAPI staining. The changes in p53 expression were revealed by the immunostaining method.

Results: ALA/protoporphyrin IX (PpIX) was mainly located in the cytoplasm of HepG2 cells. The maximal cellular uptake occurred after 18 h in vitro incubation. The photocytotoxic assay showed that ALA PDT induced 80% killing at 2 mM drug dose and 2 J/cm2 light intensity. Up to 70% of cells showed membrane blebbing and positive DAPI staining, indicating that ALA–PDT-mediated cell death was predominantly via apoptosis. In addition, p53 was upregulated after treatment, implying that p53 might evoke apoptotic cell death.

Conclusions: HepG2 cell line is sensitive to ALA-mediated PDT. ALA–PDT induces apoptosis in the HepG2 cell line that may be mediated by a p53-dependent pathway.