대한대장항문학회

Purpose: Photodynamic therapy (PDT) is a relatively new technology for an alternative modality in the treatment of colorectal cancers. This study was conducted to identify the appropriate dosage and energy level for the photosensitizer as well as effect of PDT on colon cancer cells. <br>Methods: Colon cancer cell line, COLO 205 (American Type Culture Collection, ATCC) was obtained from Korea Cell Line Bank (KCLB, Seoul, Korea). Cells were cultured on RPMI 1640 medium with 10% fetal calf serum, penicillin, and gentamicin. Cells were incubated at 37°C in a 5% CO2 air environment. Photosense (sulphonated aluminum phthalocyanine, AlPcS4, NIOPIK, State Research Center, Moscow, Russia) was used for the photosensitizer and Fireplace video-3 (Biospec, General Physics Institute, Moscow, Russia, 500 mW/cm2, 670 nm) was used for the light source. 1×104 cells were incubated in 96 well plates with different concentrations of aluminum phthalocyanine: 0.1, 0.3, 0.5 and 1μM for 24 hours then photoirradiation was performed at either 24 or 48 J/cm2. The time variations of the viabilities of cells of the four study groups and were measured by using MTT assay according to time were compared to those of the three control groups: control (no treatment), control (AlPcS4, no light), control (light, no AlPcS4), and the study groups (PDT) at one hour, 24 hours, 48 hours and 72 hours after PDT. <br>Results: At, one hour after PDT, the viability of the cells was not changed in the control groups. Viabilities of 117, 40, 35, and 23% in the 24 J group and 76, 31, 52, and 48% in 48 J group were observed, respectively in order of increasing concentration with the value of 87～103% for the control group. 24 hours later, viability of control groups were not changed, By 24 hour after PDT, the viabilities of the control groups had not changed, but those of the 24 J/cm2 and 48 J/cm2 PDT study groups had decreased significantly to 62, 17, 16, and 18% and 24, 15, 13, and 13%, respectively (P=0.00). By 48 hours viability of the 24 J/cm2 and 48 J/cm2 PDT study groups were also significantly decreased being 103, 26, 13, and 13% and 50, 8, 8, and 9%, respectively (P=0.00). By 72 hours, viabilities were 84, 21, 21, and 30 % and 33, 20, 33, and 15%, respectively (P=0.00). <br>Conclusions: The PDT groups showed a marked cytotoxic effect compared to the control groups, and the effect appeared just after PDT and peaked in 48 hours. The minimum required concentration of the photosensitizer for effective cytotoxicity was at 0.3μM either 24 or 48 J/㎠