Treatment with Light-Emitting Diodes of Wavelength 863 nm Delays DMBA/TPA-Induced Skin Tumor Formation and Decreases Proinflammatory Cytokine Levels in ICR Mice.

The popularity of light/energy devices for cosmetic purposes (e.g., skin care) is increasing. However, the effects and underlying mechanisms remain poorly understood. Commencing in the 1960s, various studies have evaluated the beneficial effects of a light source on cells and tissues. The techniques evaluated include low-level light (laser) therapy and photobiomodulation (PBM). Most studies on PBM used red light sources, but, recently, many studies have employed near-infrared light sources including those of wavelength 800 nm. Here, we used a light-emitting diode (LED) array with a wavelength of 863 nm to treat DMBA/TPA-induced mouse skin tumors; treatment with the array delayed tumor development and reduced the levels of systemic inflammatory cytokines. These results suggest that light therapy could be beneficial. However, the effects were small. Further studies on different skin tumors using an optimized LED setup are required. Combination therapies (conventional methods and an LED array) may be useful.

470 nm LED Irradiation Inhibits the Invasiveness of CD133-positive Human Colorectal Cancer Stem Cells by Suppressing the Cyclooxygenase-2/prostaglandin E2 Pathway.

BACKGROUND/AIM: Recurrence and metastasis of cancer caused by cancer stem cells (CSCs) is a challenge to overcome. Low level laser therapy is a new treatment strategy to suppress their invasiveness. We have assessed the inhibitory effects of 470 nm blue LED on the invasiveness of them to determine the molecular mechanisms of anti-invasiveness. MATERIALS AND METHODS: The effects of blue LEDs on their viability, proliferation and invasion were analyzed using MTT and transwell methods. In addition, the anti-invasiveness effect of blue LED on them was evaluated by zymography, semi-quantitative RT-PCR and western blot analysis. RESULTS: Irradiation with blue LED at 3 J/cm2 resulted in inhibition of their viability, proliferation and invasiveness. Their matrix metalloproteinase 2 (MMP-2) and MMP-9 activities were reduced by blue LED irradiation. Semi-quantitative RT-PCR also showed similar results. In addition, western blotting analyses showed that cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) synthesis were significantly inhibited by LED irradiation in CD133+ colorectal CSCs. CONCLUSION: Down-regulation of the COX-2/PGE2 signaling pathway by blue LED irradiation led to reduce expression of MMP-2 and MMP-9, inhibiting the invasiveness of CD133+ colorectal CSC.

Light-emitting diode irradiation using 660 nm promotes human fibroblast HSP90 expression and changes cellular activity and morphology.

We evaluated changes in cell viability and morphology in response to low-level light irradiation and underlying variations in the levels of heat shock proteins (HSPs). Human fibroblasts were irradiated with a light-emitting diode (LED) array at 660 nm (50 mW for 15, 30, and 60 minutes). Cell viability and morphological changes were evaluated via epifluorescence analysis; we also assessed cell viability and length changes. The expression levels of adenosine triphosphate (ATP) and various HSPs (HSP27, 60, 70, and 90) were analyzed by immunohistochemical staining, Western blotting and microarray analysis. After LED irradiation, cellular viability and morphology changed. Of the several HSPs analyzed, the HSP90 level increased significantly, suggesting that this protein played roles in the morphological and cellular changes. Thus, low-level irradiation triggered cellular changes mediated by increased HSP90 expression; this may explain why skin irradiation enhances wound-healing.

Low-Level Laser Therapy Promoted Aggressive Proliferation and Angiogenesis Through Decreasing of Transforming Growth Factor-ß1 and Increasing of Akt/Hypoxia Inducible Factor-1α in Anaplastic Thyroid Cancer.

OBJECTIVE: We assessed the cause of increased tumor after low-level laser therapy (LLLT) by histological analysis. BACKGROUND DATA: LLLT is a nonthermal phototherapy used in several medical applications, including wound healing, reduction of pain, and amelioration of oral mucositis. We discovered by accident that LLLT increased tumor size while testing a photodynamic therapy (PDT) model for the treatment of thyroid cancer. Although therapeutic effects of LLLT on cancer or dysplastic cells have been studied, LLLT has been recently reported to stimulate the aggressiveness of the tumor. METHODS: The anaplastic thyroid cancer cell line FRO was injected into thyroid glands of nude mice orthotopically and then laser irradiation was performed with 0, 15, and 30 J/cm(2) (100 mW/cm(2)) on the thyroid after 10 days. The tumor volume was measured for 4 weeks and the thyroid tissues underwent histological analysis. We observed that proliferation of FRO cells and macrophage infiltration was increased with energy delivery to the thyroid glands. We also assessed overproliferated FRO cells using an immunohistochemical staining with hypoxia inducible factor 1α (HIF-1α), p-Akt, vascular endothelial growth factor (VEGF), and transforming growth factor ß1 (TGF-ß1). RESULTS: HIF-1α and p-Akt were elevated after LLLT, which suggested that the phosphorylation of Akt by LLLT led to the activation of HIF-1α. Moreover, TGF-ß1 expression was decreased after LLLT, which led to loss of cell cycle regulation. CONCLUSIONS: In conclusion, LLLT led to a decrease in TGF-ß1 and increase of p-Akt/HIF-1α which resulted to overproliferation and angiogenesis of anaplastic thyroid carcinoma (ATC). Therefore, we suggest that LLLT can influence cancer aggressiveness associated with TGF-ß1 and Akt/HIF-1α cascades in some poorly differentiated head and neck cancers.