Upregulation of Phosphorylated HSP27, PRDX2, GRP75, GRP78 and GRP94 in Acquired Middle Ear Cholesteatoma Growth

Kuen Ho,Chee Chai,Yu Wu,Wan Chen,Shih Tsai,Hsun Wang,Tai Yeh,Chen Chien,Han Huang,Ning Chang,Kuo Hung

doi:10.3390/ijms140714439

Abstract

Cholesteatoma is a destructive and expanding growth of keratinizing squamous epithelium in the middle ear or petrous apex. The molecular and cellular processes of the pathogenesis of acquired middle ear cholesteatoma have not been fully understood. In this study, comparative proteomic analysis was conducted to investigate the roles of specific proteins in the pathways regarding keratinocyte proliferation in cholesteatoma. The differential proteins were detected by comparing the two-dimension electrophoresis (2-DE) maps of the epithelial tissues of 12 attic cholesteatomas with those of retroauricular skins. There were 14 upregulated proteins in the epithelial tissues of cholesteatoma in comparison with retroauricular skin. The modulation of five crucial proteins, HSP27, PRDX2, GRP75, GRP78 and GRP94, was further determined by RT-PCR, Western blot and immunohistochemistry. Phosphorylation of HSP27 at Ser-82 was identified by mass spectroscopy. The results of this study suggested that phosphorylated HSP27 is the end expression of two potential signal-transduction pathways, and together with PRDX2, they are very likely involved in the proliferation of keratinocytes in cholesteatoma. Upregulations of GRP75, GRP78 and GRP94 in keratinocytes may be able to counter endoplasmic reticulum stress, to inhibit cell apoptosis, to prevent protein unfolding and to promote cholesteatoma growth.

Highlights

Cholesteatoma is a destructive and expanding growth of keratinizing squamous epithelium in the middle ear cavity [1,2,3,4,5]
The results in the current study indicated that the expression of GRP75, Glucose-regulated protein 78 (GRP78) and Glucose-regulated protein 94 (GRP94) in the tissues of cholesteatoma is higher than that in retroauricular skin
We verified the changes of these crucial signaling factors by Western blot in cholesteatoma. These data in our study suggest that Heat shock protein 27 (HSP27) together with the Ras/Raf/ERK1/2 and MAPK pathways may be relevant in stimulating keratinocyte proliferation and differentiation in cholesteatoma

Summary

Introduction

Cholesteatoma is a destructive and expanding growth of keratinizing squamous epithelium in the middle ear cavity [1,2,3,4,5]. A perforation of the eardrum caused by chronic infection or direct trauma could lead to cholesteatoma. The skin over the outer surface of the eardrum could grow through the perforation and into the middle ear. Small remnants of skin of the eardrum (retraction pocket) are trapped into the middle ear in most patients [6]. Local infection leads to a disturbance of self-cleaning mechanisms. Imbalance and vicious circles of epithelial proliferation, keratinocyte differentiation and maturation, prolonged apoptosis and disturbance of self-cleaning may occur. The inflammatory stimulus can induce an epithelial proliferation along with expression of lytic enzymes and cytokines [1,2,3]. Bacteria inside the retraction pocket produce some antigens, which are able to activate different cytokines and lytic enzymes [4,5]

Methods

Discussion

Conclusion