title: Lumican expression is associated with the formation of mesenchyme-like elements in salivary pleomorphic adenomas.
abstract: Pleomorphic adenomas are the most common salivary gland tumour. Although this tumour is considered to be of epithelial origin, it contains 'mesenchyme'-like elements histologically. Lumican is a keratan sulphate proteoglycan that belongs to the small leucine-rich repeat (LRR) proteoglycans and has been reported to be associated with cartilage formation. These findings suggest that lumican expression may be related to the chondroid component in pleomorphic adenomas. To investigate this hypothesis, the present study investigated the expression and localization of lumican in 20 normal human salivary glands and 35 pleomorphic adenomas. Firstly, immunohistochemistry for lumican was performed with pepsin pretreatment. In normal salivary glands, lumican was deposited in the periductal regions. In pleomorphic adenomas, it was predominantly deposited in the hyaline (100%) and fibrous areas (89.4%). In 16 tumours (66.7%), lumican was also deposited in the chondroid areas. Without pepsin pretreatment, lumican was identified in myoepithelial cells in myxoid areas, lacuna cells in chondroid areas, and in the cytoplasm of inner ductal cells. In situ hybridization revealed lumican mRNA expression mainly in the inner cells, the neoplastic myoepithelial cells, and the lacuna cells. These results suggest that lumican is associated with the formation of 'mesenchyme'-like structures in pleomorphic adenomas. In conclusion, normal salivary glands express lumican, which appears to be related to stromal maintenance, and pleomorphic adenomas express lumican mRNA and protein, which may play important roles in the formation of 'mesenchyme'-like areas in this type of tumour.
authors.affiliation: Department of Transplantation for Regeneration Therapy, Sponsored by Otsuka Pharmaceutical Co, Ltd, Kansai Medical University, 10-15 Fumizono-cho, Moriguchi, Osaka 570-8506, Japan. kusahukk@takii.kmu.ac.jp
authors.forename: Kimihide
authors.initials: K
authors.lastname: Kusafuka
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ishiwata
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sugisaki
authors.forename: Tamiko
authors.initials: T
authors.lastname: Takemura
authors.forename: Michi
authors.initials: M
authors.lastname: Kusafuka
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hisha
authors.forename: Susumu
authors.initials: S
authors.lastname: Ikehara
mesh_terms: D008949:Adenoma, Pleomorphic / Q000378:metabolism* / Q000473:pathology; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D017403:In Situ Hybridization; D007632:Keratan Sulfate / Q000235:genetics / Q000378:metabolism*; D000071234:Lumican; D008648:Mesoderm / Q000473:pathology*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D012468:Salivary Gland Neoplasms / Q000378:metabolism* / Q000473:pathology; D012469:Salivary Glands / Q000378:metabolism
chemical_list: D011508:Chondroitin Sulfate Proteoglycans; C000604306:LUM protein, human; D000071234:Lumican; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D007632:Keratan Sulfate