Effect of Light Irradiation by Light Emitting Diode on Colon Cancer Cells

Background/Aim: Recent studies have demonstrated the efficacy of irradiation from light emitting diodes (LED) for wound healing, anti-inflammation and anticancer therapies. However, little is known about the effects of visible light in colon cancer cells. The purpose of this study was to evaluate the biological response (including gene expression changes) of human colon cancer cells to different wavelengths of LED irradiation. Materials and Methods: Human colon cancer cells (HT29 or HCT116) were seeded onto laboratory dishes that were then put on LED irradiation equipment with a 465 nm-, 525 nm-, or 635 nm-LED. Irradiation at 15 or 30 mW was performed 10 min/day, each day for 5 days. The cell counting kit8 was then used to measure cell viability. Apoptosis and expression of several mRNAs (caspase, MAPK and autophagy pathway) in HT29 cultures irradiated with 465 nm LED were evaluated via Annexin V/PI and RT-PCR, respectively. Results: Viability of HT29 and HCT116 cells was lower in 465 nm-LED irradiated cultures than in control cultures, but viability of HT29 cells did not differ between control cultures and 525 nm-LED or 635 nm-LED irradiated cultures. Moreover, the expression of FAS, caspase-3, capase-8, and JUK were significantly higher in 465 nm-LED irradiated cultures than in control cultures, and expression of ERK1/2 and LC3 was lower in blue-irradiated cells. Conclusion: LED irradiation at 465 nm inhibited the proliferation of HT29 cells and of HCT116 cells. Notably, LED irradiation at 465 nm promoted apoptosis inHT29 cultures via the extrinsic apoptosis pathway and the MAPK pathway.

内容要旨・審査要旨・論文本文の公開:
内容要旨・審査要旨 : LID201505141007.pdf
論文本文 : k2794_fulltext.pdf
本論文は,著者NORIKO MATSUMOTOの学位論文として提出され, 学位審査・授与の対象となっている。
著者の申請により要約(2015-05-15公開)に替えて論文全文を公開(2022-12-14)