Differential expression of perlecan receptors, a-dystroglycan and integrin b1, before and after invasion of oral squamous cell carcinoma Md. Shahidul Ahsan 1 , Manabu Yamazaki 1 , Satoshi Maruyama 2 , Takanori Kobayashi 2 , Hiroko Ida-Yonemochi 2 , Mayumi Hasegawa 1 , Adeola Henry Ademola 1 , Jun Cheng 1 , Takashi Saku 1,2 1 Division of Oral Pathology, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan; 2 Oral Pathology Section, Department of Surgical Pathology, Niigata University Hospital, Niigata, Japan OBJECTIVES: The deposition of perlecan, a heparan sulfate proteoglycan, is enhanced within oral carcinoma in situ (CIS) foci, while it dynamically switches from CIS foci to the stromal space in squamous cell carcinoma (SCC). Because a-dystroglycan and integrin b1 have been identified as two of the perlecan receptors, we wanted to determine their differential distributions before and after invasion of oral SCC. METHODS: Eighty-two surgical tissue specimens of oral SCC containing different precancerous stages were examined by immunohistochemistry for perlecan, a-dys- troglycan, integrin b1, and Ki-67. In addition, a-dystro- glycan mRNA signals were localized by in situ hybridization. RESULTS: In normal epithelia, a-dystroglycan and inte- grin b1 were localized on the cell membrane of basal cells, while perlecan was faintly present in the intercellular spaces of parabasal cells. In epithelial dysplasia and CIS, a- dystroglycan and perlecan were well co-localized in the epithelial layer, especially in its lower half, and this co- localization was mostly overlapped with Ki-67-positive (+) cell zones. However, in SCC, a-dystroglycan was localized neither within carcinoma cell nests nor in the stroma, while perlecan disappeared from SCC foci but emerged in the stromal space, leaving integrin b1+ and Ki-67+ cells only to the periphery of SCC foci. a-Dystroglycan mRNA signals were basically identical to the a-dystroglycan protein localizations. CONCLUSION: The findings suggest that a-dystroglycan and integrin b1 act as perlecan receptors in oral precan- cerous lesions prior to invasion, and that the perlecan signals via the two different receptors function in cellular differentiation and proliferation of CIS cells, respectively. J Oral Pathol Med (2010) 40: 552–559 Keywords: carcinoma in situ; a-dystroglycan; integrin b1; oral mucosa; perlecan; squamous cell carcinoma Introduction ÔLoss of intercellular adherence’ (1) or enlargement of the intercellular space is one of the important histo- pathological characteristics of epithelial dysplasia or carcinoma in situ (CIS) of the oral mucosa (2, 3). This enlargement of the intercellular space of these squamous epithelial cells results from the deposition of an extra- cellular matrix (ECM) molecules such as perlecan (2–4). Perlecan, a basement membrane-type heparan sulfate proteoglycan (HSPG), is expressed in various patho- physiologic events ranging from tooth enamelogenesis (5) to inflammatory (6) as well as neoplastic (7–9) conditions. Among these varieties of perlecan expression modes, we have been most interested in the phenome- non of intraepithelial deposition of perlecan (2, 10). While keeping cell–cell adhesion, epithelial cells seem to communicate with intercellular perlecan that at the same time acts as reservoirs of various kinds of cell growth factors (11, 12). Based on these lines of evidence, we have proposed the concept of Ôintraepithelial stroma,’ by which epithelial cells can survive or even proliferate in a hypoxic circumstance of the epithelial layer where blood vessels are not allowed to enter because of the presence of basement membranes (2, 3, 13–15). It is well established that alterations in the interac- tions of cell–cell and cell–ECM adhesion molecules are common features of malignant tumors and a crucial step for initiation of tumor cell invasion (16). Integrins are a major family of adhesion molecules that bind ECM molecules to the cell surface, and integrin b1 is known to be one of the major receptors for perlecan (17). Engagement of integrins activates their multiple Correspondence: Takashi Saku, Division of Oral Pathology, Depart- ment of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences. 2-5274 Gakkocho- dori, Chuo-ku, Niigata 951-8514, Japan. Tel: 81 25 227 2832, Fax: 81 25 227 0805, E-mail: tsaku@dent.niigata-u.ac.jp Accepted for publication November 17, 2010 J Oral Pathol Med (2011) 40: 552–559 ª 2010 John Wiley & Sons A/S Æ All rights reserved wileyonlinelibrary.com/journal/jop doi: 10.1111/j.1600-0714.2010.00990.x Journal of Oral Pathology & Medicine