Recently,
indole-3-acetic acid (IAA) has been introduced as a new
cancer therapeutic agent through oxidative decarboxylation by
horseradish peroxidase (HRP). The purpose of this study was to determine the therapeutic feasibility of IAA/light combination against
liver cancer. SK-HEP-1 cells were irradiated with UVB or visible light (518 nm) in the presence of IAA. Cell viability was measured using a
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Then, IAA was injected in SK-HEP-1
liver cancer cell-implanted nude mice, and the
tumor area was irradiated with intense pulsed light (IPL). Then, tissue was taken for
terminal deoxynucleotidyl transferase-mediated
deoxyuridine triphosphate nick-end labeling (TUNEL) assay and immunohistochemical staining for 8-hydroxy-deoxyguanosine (8-OHdG), p53,
caspase-3, and
proliferating cell nuclear antigen (
PCNA). In vitro experiments demonstrated that IAA alone was not cytotoxic, but activated IAA by HRP or light caused cell death. In vivo experiments showed that IAA/IPL treatment caused regression of
tumor cells in SK-HEP-1-implanted nude mice. The TUNEL assay showed that IAA/IPL induced
cancer cell apoptosis, and this was confirmed by increases in 8-OHdG, p53, and
caspase-3 in IAA/IPL-treated mice. In contrast, IPL alone did not induce apoptosis, indicating that the apoptotic effect resulted from activated IAA by light. In summary, we showed that IAA/light induced
tumor regression in SK-HEP-1-implanted nude mice. These results suggest the potential use of IAA/light combination in
liver cancer.