Immunological evidence for the identity between the hsp27 estrogen-regulated heat shock protein and the p29 estrogen receptor-associated protein in breast and endometrial cancer

Abstract

Previous studies have shown several similarities between an estrogen-regulated heat shock protein of 24,000-28,000 daltons (hsp27), and a cytoplasmic estrogen receptor-associated protein of 27,000-29,000 daltons (p29). These proteins have been studied by monoclonal antibodies generated in different laboratories. In the present report we have performed immunocytochemical and immunoblot studies to explore if the monoclonal antibodies against hsp27 (C11) and against p29 (ER-D5) may be identifying the same protein. Breast and endometrial carcinomas and normal endometrial samples were examined by immunocytochemistry (in mirror sections and by double-immunostaining). Identical hsp27 and p29 immunostaining intensity, distribution, and percentage of stained cells was demonstrated by immunocytochemistry. The antigens examined by the two antibodies appeared in the same cells. Cytosols from tumors analyzed by the Western blot technique revealed that the C11 and the ER-D5 antibodies recognized bands with identical electrophoretic mobility. Immunoprecipitation studies with one antibody, C11, followed by Western blot showed that the precipitate was reactive with both antibodies. Identical C11 and ER-D5 reacting spots were observed after blotting proteins separated by high resolution two-dimensional gel electrophoresis. In addition, p29 protein was induced by heat shock in the estrogen receptor negative MDA-MB-231 human breast tumor cell line. These results strongly suggest that the two proteins under investigation are identical.

Hsp-27 Expression in Invasive Ductal Breast Carcinoma

“…Hsp27, which is also known as a cytoplasmic estrogen receptor associated protein (p29), selectively binds GTP and to a lesser extent ATP and plays a role in the estrogen response intracellular pathways [33,34]. Our study did not show any correlation between Hsp27 expression and the expression of ER and PR.…”

A 27 kDa heat shock protein that has anomalous prognostic powers in early and advanced breast cancer

“…We have been interested in a different type of protein, a low molecular weight (27 kDa) heat shock protein (HSP27). This is an abundant protein that has previously been discussed under three different names, p29 King et al, 1987), p24 (Ciocca et al, 1983;Adams & McGuire, 1985) and srp27 (Thor et al, 1991), but it is now known that they are one and the same protein (Mendelsohn et al, 1991;Ciocca & Luque, 1991) and will henceforth be called HSP27. HSP27 is a widely distributed protein, although levels attained in breast cancers exceed those found in other cells (Dunn et al, 1993).…”

Expression of Heat Shock Proteins 27 and 70 in Renal Cell Cancer and Normal Renal Tissue: An Immuohistochemical Study

“…HSP27 is identical with the 24-kD protein detected in the human breast cancer line MCF-7 [10] and has since been described in endometrial carcinoma [11], cervical cancer, acute lymphoblastic leukemia, testicular cancer, gastric cancer, and malignant fibrous histiocytoma. Immunohistochemical expression of HSP27 has been associated with poor survival in breast and gastric cancer [1] and improved patient survival in malignant fibrous histiocytoma [12].…”