1. University of Sheffield, Section of Medicine, Division of Clinical Sciences, Northern General Hospital, Sheffield, U.K.
2. ^*University of Sheffield, Department of Engineering Materials, Sir Robert Hadfield Building, Mappin Street, Sheffield, U.K.
3. ^†Laboratory of Oncology and Experimental Surgery, Institut Bordet, Université Libre de Bruxelles, Belgium

Correspondence: Dr John W. Haycock, Department of Engineering Materials, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, U.K. Email: j.w.haycock@shef.ac.uk

Received 15 June 2001; Revised 24 April 2002; Accepted 27 May 2002.

Abstract

-Melanocyte stimulating hormone (-MSH) has pigmentary, anti-inflammatory, antipyretic, and general immunomodulatory roles. It can oppose several cytokines including tumor necrosis factor- in a number of tissues, including skin. We have previously shown that -MSH can inhibit tumor necrosis factor- stimulated intercellular adhesion molecule 1 upregulation and nuclear factor B (NFB) transcription factor activation in melanocyte and melanoma cells. It is thought, however, that this MSH biology may also extend to other cells of the skin and in this study we extend our work to keratinocytes. We have investigated in detail the ability of three -MSH peptides to inhibit tumor necrosis factor stimulated NFB activation in nonpigmentary HaCaT keratinocytes (-MSH, L-Lys-L-Pro-L-Val, and L-Lys-L-Pro-D-Val) and two adrenocorticotropic hormone (ACTH) peptides (1–17 and 1–39), reported to be present in skin tissue. NFB/p65 activation was analyzed by electrophoretic mobility shift assay and immunofluorescent microscopy. -MSH, L-Lys-L-Pro-L-Val, and L-Lys-L-Pro-D-Val all significantly inhibited tumor necrosis factor stimulated NFB activation, whereas ACTH 1–17 and 1–39 did not, in the HaCaT keratinocytes. MSH peptides and ACTH 1–39 were effective, however, at inhibiting NFB activation in normal human keratinocytes. Immunolabeling of inhibitor B of NFB (IB) revealed an abnormal localization to the nucleus of HaCaT cells, which was unaffected by MSH/ACTH peptides. In contrast, normal human keratinocytes showed a normal IB distribution that responded to MSH/ACTH with nuclear translocation. Our data support previous work on the role of MSH/ACTH peptides as immunomodulatory/anti-inflammatory regulators, and extend this work to keratinocytes identifying a novel IB mechanism and extends findings to ACTH peptides, identifying an abnormal IB mechanism in the immortal HaCaT versus normal keratinocyte.