Investigation of the effect of ALA-5-mediated photodynamic therapy on colon cancer cell line by using laser and LED light source systems in vitro

Photodynamic therapy (FDT) is a clinically approved type of therapy for the treatment of cancer and some non-malignant diseases. By selectively accumulating a light-sensitive substance called photo-sensitive substance (FDM) in the tumor in the target tissue and stimulating it with light at the appropriate wavelength, it produces reactive oxygen species (ROS) in the tissue and initiates a series of events that cause the death of the cancer cell. Thus, it is a type of treatment that destroys only the tumor tissue without any damage to the healthy tissue. Parameters such as photo-sensitive substance, light source, wave mode, tumor type, tumor size and location affect FDT activity. Laser and LED (light emitting diode - light emitting diodes) are commonly used in FDT. Various wave pulse modes have been used in recent years to prevent thermal damage during photodynamic therapy: continuous, pulse and superbeat modes. In this study, 5-aminolevulinic acid (ALA-5) photo sensitive substance approved by the US Food and Drug Administration (FDA) was used in HT-29 colon cancer cell line. The effect of ALA-5 mediated photodynamic therapy on HT-29 colon cancer cell line was investigated using two different wave modes in laser and LED-induced systems. Continuous wave mode (CW) and pulse wave mode (PM) are used with 635 nm wavelength laser and LED sources. In HT-29 colon cancer cell line, appropriate ALA-5 dose and light dose parameters were determined by MTT and XTT analyzes. Photodynamic therapy was carried out with 1 mM ALA-5 concentration and energy densities of 10 〖J/cm〗^2, 15 〖J/cm〗^2 and 20 〖J/cm〗^2. As a control, the WI-38 lung fibroblast cell line was studied. Accordingly, it was seen that effective ALA-5 concentration and light dose determined did not inhibit cell proliferation alone. Photodynamic therapy was applied in laser and LED-based systems using the determined doses, using continuous and pulse wave modes. 24 hours after treatment, cell cytotoxicity was investigated by XTT analyzes. As a result, as a result of photodynamic therapy with both systems, cell proliferation decreased and continuous wave mode caused more cell cytotoxicity. Keywords: Photodynamic therapy, colon cancer, laser light source, LED light source, ALA-5