Regulatory Effects of Heat on Normal Human Melanocyte Growth and Melanogenesis: Comparative Study with UVB

• Published in: Journal of investigative dermatology Vol. 110; no. 6; pp. 972 - 977
• Main Authors: Nakazawa, Keiko, Sahuc, Florent, Damour, Odile, Collombel, Christian, Nakazawa, Hisayoshi
• Format: Journal Article
• Language: English
• Published: Danvers, MA Elsevier Inc 01.06.1998; Nature Publishing; Nature Publishing Group
• Subjects: Biochemistry, Molecular Biology; Biological and medical sciences; Cell Division - physiology; Cell Division - radiation effects; Cells, Cultured; Coculture Techniques; Dermatology; Dihydroxyphenylalanine - metabolism; Dihydroxyphenylalanine - radiation effects; Hot Temperature; Humans; Investigative techniques, diagnostic techniques (general aspects); Keratinocytes - cytology; Keratinocytes - metabolism; Keratinocytes - radiation effects; Life Sciences; Medical sciences; Melanins - metabolism; Melanins - radiation effects; Melanocytes - cytology; Melanocytes - physiology; Melanocytes - radiation effects; Membrane Glycoproteins; Monophenol Monooxygenase - metabolism; Monophenol Monooxygenase - radiation effects; Oncogene Protein p21(ras) - biosynthesis; Oncogene Protein p21(ras) - radiation effects; Oxidoreductases; p21; p53; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Proteins - metabolism; Proteins - radiation effects; Skin - cytology; Skin - metabolism; Skin - radiation effects; Skin Pigmentation - physiology; Skin Pigmentation - radiation effects; TRP-1; Tumor Suppressor Protein p53 - biosynthesis; Tumor Suppressor Protein p53 - radiation effects; Ultraviolet Rays; TRP-1; p21; p53; Human; Cell culture; Heat; Growth; Morphology; Melanocyte; Epidermis; Physiology; Melanogenesis; Pigmentation
• ISSN: 0022-202X; 1523-1747
• DOI: 10.1046/j.1523-1747.1998.00204.x

Although energy-rich ultraviolet B (UVB) is considered to be primarily responsible for most of the effects associated with solar radiation, small energy recorded as heat appears to contribute to the biologic effects of solar radiation on the skin. We compared the effects of heat and UVB on normal human melanocyte functions. In monolayer culture the following was found. (i) Heat-treated melanocytes showed an increased dendricity and exhibited a larger cell body compared with nontreated melanocytes. (ii) After multiple treatments with UVB (20 mJ per cm2, 312 nm) or heat (42°C for 1 h) for 3 d, melanocytes had a lower survival than nontreated melanocytes, but they resumed proliferation within 6 d in the same manner as seen in control. (iii) The expression levels of cell cycle regulators, p53 and p21 proteins, were increased after multiple treatments with UVB or heat. (iv) The tyrosinase (dopa-oxidase) activity per cell was increased after the multiple treatments with UVB or heat. (v) The number of dopa-positive melanocytes in coculture with keratinocytes in epithelial sheets was greatly increased by UVB or heat treatments. (vi) Similarly, the increased number of tyrosinase-related protein 1 positive melanocytes was seen in skin equivalents after UVB (100 mJ per cm2) or heat (42°C for 1 h) treatments for 7 d. These results suggest that heat shares significant biologic activities with UVB in melanocyte functions. These results could be considered as one of the protective or adaptive responses of the skin pigmentary system to the environment.