Figure 1. Effects of 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) on ALDH1 activity in HNSCC cell lines and primary HNC cells.

(A) HNC cell lines (SAS and Ca9-22) and primary HNC cells (HNC-1 and HNC-2) were seeded as 1×10⁶ cells/well in 6-well-plate and then pretreated 1 mM ALA for 3 hr followed by PDT with red light at a dose of 4 J/cm2 or ALA only treatment control group. ALDH+ cells were determined by Alderfluor assay and viable cells (7-AAD negative) were used for analysis. DEAB-treated cells were used as negative control. (B) The quantification results were shown in bar graph. The experiments were repeated three times and representative results were shown. Results are presented as means ± SD *, p<0.05.