An immunohistochemical study of the localization of inducible nitric oxide synthase (iNOS) and heat shock protein (HSP) in pleomorphic adenoma

The present study investigated the localization of inducible NOS (NOS), heat shock protein (HSP) 27, HSP60 and HSP70 in 25 cases of pleomorphic adenoma. Immunohistochemical staining for MOS and HSPs was widely observed in neoplastic epithelia. In the stromal tissues, the cells showed both positive and negative staining with MOS or HSPs. Staining for HSP27 was limited to the cytoplasm, and was more intense for HSP60 and 70. Both iNOS and HSPs were presumed to be localized mainly in myoepithelial cells in pleomorphic adenoma, and their localizations were mostly overlapped. These results indicated that iNOS and HSPs may be involved, at least in part, in the development of pleomorphic adenoma.