An animal study of the effects on p16 and PCNA expression of repeated treatment with high-energy laser and intense pulsed light exposure

• Published in: Lasers in surgery and medicine 2007-01, Vol.39 (1), p.8-13
• Main Authors: Chan, Henry H.L., Yang, C.H., Leung, Joseph C.K., Wei, W.I., Lai, K.N.
• Format: Article
• Language: English
• Subjects: Animals; Biomarkers; Genes, p16 - radiation effects; Lasers - adverse effects; Low-Level Light Therapy - adverse effects; Male; Mice; Mice, Inbred ICR; non-ablative; p16; PCNA; Proliferating Cell Nuclear Antigen - radiation effects; Skin - radiation effects; Time
• ISSN: 0196-8092; 1096-9101
• DOI: 10.1002/lsm.20447

Background and Objective Non‐ablative skin rejuvenation treatments that involve the use of laser/light sources together with cooling devices have gained much popularity in recent years due to the lack of down time that is associated with them. One important but neglected issue is long‐term safety. Does the repeated use of non‐ablative skin rejuvenation lead to photoaging? Are we creating another sun‐bed phenomenon? Recently, we performed an in vitro study to examine the effect of sub‐lethal QS 755 nm lasers on the expression of p16INK4a on melanoma cell lines, and found that sub‐lethal laser damage could increase DNA damage, which led to an increase in p16 expression. Our objective was to assess the cutaneous effect of repeated exposure to high‐energy lasers and intense pulsed light sources on male Institute of Cancer Research (ICR) mice. Study Design/Materials and Methods Twenty‐eight male ICR mice were divided into four groups. Other than the control group, all groups received either laser (585 nm pulsed dye laser or 1,320 nm Nd:YAG laser) or intense pulsed light (IPL) treatment. All four groups were anesthetized with a mixture of Hypnorm/Dormicum before treatment. The animals were irradiated twice a week for 6 months. Signs of toxicity such as mortality and weight loss were checked once a week. Skin tumor formation was evidenced by lesions of greater than 1 mm in diameter that persisted for 2 weeks. At the end of the 6 months, the expression of proliferating cell nuclear antigen (PCNA) and p16 in the mouse skin was determined by immunohistochemical staining and immunoblotting using specific monoclonal antibodies for mouse PCNA and p16. The results were expressed as mean ± standard error of the mean (SEM). Statistical difference was assessed by multiple ANOVA. A P‐value of