The Effects of Ultraviolet Radiation on Aging and p53 Expression in Human Skin / 대한피부과학회지

ABSTRACT

BACKGROUND: Long-term phototherapy can induce the changes of photoaging and it is reported that there is an increased chance of cutaneous squamous cell carcinomas in patients exposed to large amounts of UV radiation. OBJECTIVE: The main objective was to investigate the degree of photoaging and the presence of p53 mutations in normal skin in patients undergoing long-term phototherapy. METHOD: We performed hematoxylin-eosin and special stains, p53 and p21 immunohistochemical stains and polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) on the normal skin of patients subject to long-term UV therapy. RESULT: 1. The typical features of photoaging were not observed in patients undergoing long-term UV therapy. 2. In p53 immunohistochemical staining performed at 1 week after cessation of long-term PUVA treatment, the patient group with a culmulated UV dosage of more than 1,000J/cm2 demonstrated an increased number of p53 positive epidermal cells compared to exposed as well as unexposed normal skins. 3. The patterns of p21 immunohistochemical staining performed at 1 week after cessation of long-term PUVA and UVB treatments were similar to that of p53 immunohistochemical staining performed at 1 week after cessation of phototherapy. 4. In p53 immunohistochemical staining performed at 4 months after cessation of UV treatment, the number of p53 positive epidermal cells decreased significantly compared to that of p53 positive epidermal cells found at 1 week after cessation of UV treatment. 5. The mutation of p53 genes was not found in PCR-SSCP analysis of biopsied skins done at 1 week after cessation of long-term PUVA and UVB treatment. CONCLUSION: Long-term phototherapy did not induce the typical changes of photoaging and p53 overexpression in the epidermis of UV treated skin was a reactive process. Therefore, UV therapy can be a relatively safe treatment modality, although a closer observation for cutaneous malignancy is warrented in the patients whose cumulated UV dosage is much higher than 1,000J/cm2.