Immunohistochemical analysis of inducible nitric oxide synthase (iNOS) and heat shock proteins (HSPs) in ameloblastomas.
BACKGROUND
To clarify the possible role of nitric oxide (NO) and stress proteins in oncogenesis and cytodifferentiation of odontogenic epithelium. Inducible NO synthase (iNOS) and heat shock proteins (HSPs) were analyzed in ameloblastomas as well as in tooth germs.


METHODS
Specimens of seven tooth germs, 36 benign ameloblastomas and five malignant ameloblastomas were examined by immunohistochemistry using antibodies against iNOS and 27-, 60- and 70-kDa HSPs (HSP27, HSP60 and HSP70).


RESULTS
Immunoreactivity for iNOS was detected in normal and neoplastic odontogenic epithelial cells and was higher in malignant ameloblastomas than in tooth germs and benign ameloblastomas. HSP27 was expressed constitutively in all odontogenic epithelial cells in tooth germs and benign and malignant ameloblastomas. Expression of HSP60 and HSP70 was detected in normal and neoplastic odontogenic epithelial cells and was prominent in cells neighboring the basement membrane. HSP60 reactivity showed no apparent difference between normal and neoplastic odontogenic epithelium, whereas HSP70 expression was slightly higher in benign and malignant ameloblastomas than in tooth germs.


CONCLUSIONS
Activation of iNOS might be associated with malignant potential of epithelial odontogenic tumors. Elevated expression of HSP70 is considered to be involved in neoplastic transformation of odontogenic epithelial cells.
Kumamoto
Hiroyuki
H
Division of Oral Pathology, Department of Oral Medicine and Bioregulation, Tohoku University Graduate School of Dentistry, Sendai, Japan.
Suzuki
Takahiro
T
Ooya
Kiyoshi
K
D000564:Ameloblastoma / Q000378:metabolism*; D002454:Cell Differentiation; D002471:Cell Transformation, Neoplastic; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis / Q000096:biosynthesis; D006360:Heat-Shock Proteins / Q000032:analysis* / Q000096:biosynthesis; D006801:Humans; D007150:Immunohistochemistry; D009062:Mouth Neoplasms / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000032:analysis* / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000032:analysis* / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D014083:Tooth Germ / Q000378:metabolism
D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D009363:Neoplasm Proteins; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II