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Terminal Differentiation of Epithelial Cells in Middle Ear Cholesteatoma: Investigation of Patterns of Expression of Protein Kinase C‐δ and Protein Kinase C‐η
Author(s) -
Miyazaki Hidemi,
Kojima Hiromi,
Tanaka Yasuhiro,
Shiwa Masanori,
Koga Tomohiko,
Moriyama Hiroshi
Publication year - 1999
Publication title -
the laryngoscope
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.181
H-Index - 148
eISSN - 1531-4995
pISSN - 0023-852X
DOI - 10.1097/00005537-199911000-00012
Subject(s) - involucrin , epidermis (zoology) , stratum spinosum , stratum granulosum , cytokeratin , keratinocyte , biology , filaggrin , microbiology and biotechnology , keratin , cellular differentiation , cholesteatoma , immunohistochemistry , anatomy , immunology , stratum corneum , medicine , biochemistry , genetics , cell culture , atopic dermatitis , gene , radiology
Objectives: The objective of this study was to elucidate the differentiation mechanism of keratinocytes in cholesteatoma. Study Design: To achieve the objective, we analyzed the expressions of various cellular proteins: the delta and eta isoforms of protein kinase C (PKCδ and PKCη), which are thought to play key roles in signal transduction in differentiation; cytokeratin 1 (CK1) and cytokeratin 10 (CK10) (cytoskeletal constitutive proteins); and involucrin (a marker of differentiation). Methods: The materials used in this study were tissue specimens obtained from cholesteatoma epidermis, normal external ear canal skin, normal inguinal skin, and psoriatic skin. Immunohistochemical staining techniques were applied to compare the expressions of the above proteins (i.e., PKCδ, PKCη, CK1, CK10 and involucrin) in those various tissues. Results: No clear differences in the patterns of expression of PKCδ and PKCη were found between the cholesteatoma epidermis and the normal external ear canal skin. These proteins were expressed mainly in the stratum spinosum and stratum granulosum, and their patterns of expression were almost the same as those of the CK1, CK10, and involucrin proteins. Conclusion: The findings of this study indicate that the terminal differentiation of keratinocytes in the cholesteatoma epidermis is the same as in normal skin tissues. It was concluded that the growth of epidermis which has undergone hyperproliferation of keratinocytes because of increased levels of various cytokines is being regulated by means of normal terminal differentiation.