BACKGROUND: Heat shock proteins (HSPs) are a family of highly conserved proteins found ubiquitously in mammalian cells, believed to be regulators of normal cell physiology and the cellular stress response. In addition, the small 27-kDa heat shock protein (HSP27) has previously been found to be a differentiation marker for keratinocytes and a prognostic marker associated with increased survival in certain cancerous tumors. METHODS: Using immunohistochemistry on routinely processed paraffin sections, we examined skin biopsies from 15 invasive melanomas, 13 intradermal nevi, and two compound nevi immunostained with a mouse monoclonal antibody to HSP27. In addition, cultured melanocytes were heat stressed at 45 degrees C for 1 h and then fixed and immunostained in order to localize HSP27 expression intracellularly. RESULTS: We found cytoplasmic and strong perinuclear staining of HSP27 in melanocytes in normal skin, in melanomas, and in nevi. Nuclear reactivity was absent. In addition, in cultured non-malignant melanocytes, HSP27 expression relocated from the cytoplasm to the nucleus with heat stress. CONCLUSIONS: To our knowledge, this investigation is the first to demonstrate that HSP27 is expressed in melanocytes in normal skin, in nevi, and in non-malignant cultured melanocytes.
BACKGROUND: Heat shock proteins (HSPs) are a family of highly conserved proteins found ubiquitously in mammalian cells, believed to be regulators of normal cell physiology and the cellular stress response. In addition, the small 27-kDa heat shock protein (HSP27) has previously been found to be a differentiation marker for keratinocytes and a prognostic marker associated with increased survival in certain cancerous tumors. METHODS: Using immunohistochemistry on routinely processed paraffin sections, we examined skin biopsies from 15 invasive melanomas, 13 intradermal nevi, and two compound nevi immunostained with a mouse monoclonal antibody to HSP27. In addition, cultured melanocytes were heat stressed at 45 degrees C for 1 h and then fixed and immunostained in order to localize HSP27 expression intracellularly. RESULTS: We found cytoplasmic and strong perinuclear staining of HSP27 in melanocytes in normal skin, in melanomas, and in nevi. Nuclear reactivity was absent. In addition, in cultured non-malignant melanocytes, HSP27 expression relocated from the cytoplasm to the nucleus with heat stress. CONCLUSIONS: To our knowledge, this investigation is the first to demonstrate that HSP27 is expressed in melanocytes in normal skin, in nevi, and in non-malignant cultured melanocytes.
Authors: Oddbjørn Straume; Takeshi Shimamura; Michael J G Lampa; Julian Carretero; Anne M Øyan; Di Jia; Christa L Borgman; Margaret Soucheray; Sean R Downing; Sarah M Short; Soo-Young Kang; Souming Wang; Liang Chen; Karin Collett; Ingeborg Bachmann; Kwok-Kin Wong; Geoffrey I Shapiro; Karl Henning Kalland; Judah Folkman; Randolph S Watnick; Lars A Akslen; George N Naumov Journal: Proc Natl Acad Sci U S A Date: 2012-05-15 Impact factor: 11.205