Cell-adhesion molecules in human meningiomas: correlation with clinical and morphological data.

Integrins form a family of cell adhesion molecules. CD44 glycoproteins are found in a wide variety of isoforms; the most common, CD44s (standard) is widely distributed, and functions as an adhesion molecule. In this study, we have investigated immunohistochemically the distribution of some VLA integrins (alpha2, alpha5 and alpha6 chains of beta1 integrins) and CD44s in 44 meningioma specimens and normal arachnoid villi. Meningiomas were of meningothelial (16), transitional (13) and fibroblastic (15) subtypes. There were 13 grade I, 19 grade II and 12 grade III (27%). Immunoprecipitates were quantified by image analysis and correlated with clinical (age, sex, location) and morphological data (histological subtypes and grades). VLA alpha5 chain was expressed by normal arachnoid villi (mainly cap cells) and by 42 out of 44 meningioma specimens. Expression was lower in fibroblastic meningiomas (P=0.02). VLA alpha2 and alpha6 chains were not observed in normal arachnoid villi. VLA alpha2 was expressed by 15 meningiomas, VLA alpha6 by 10. Interestingly, meningiomas expressing either VLA alpha2 or alpha6 were usually of grade III (P< or =(0.05). CD44s was found on various parts of arachnoid villi and in all meningiomas although expression was higher in meningothelial and transitional than in fibroblastic (P< or =0.001). These results show that VLA alpha5 and CD44s are widely expressed by arachnoid villi and meningiomas, in contrast to VLA alpha2 and VLA alpha6. It was noted that high grade meningiomas (III) express VLA alpha2 and alpha6 suggesting that changes in integrin pattern expression are a feature of these meningiomas. Moreover, strong CD44s expression characterizes meningothelial and transitional meningiomas. Previous studies have shown that high NCAM expression is a feature of fibroblastic meningiomas whereas meningothelial and transitional meningiomas expressed mainly E-Cadherin, and that polysialylated NCAM expression was restricted to high grade meningiomas. Taken together these features suggest that each cell adhesion molecule has a characteristic pattern of expression according to meningioma subtype and grade. No correlation was seen between integrins and CD44s expression and clinical data.