EXPRESSION OF HYALURONAN IN NORMAL AND DYSPLASTIC BRONCHIAL EPITHELIUM AND IN SQUAMOUS-CELL CARCINOMA OF THE LUNG

A series of 85 lung/bronchial tissue samples from 76 patients consisti ng of normal, metaplastic and dysplastic epithelium and different type s of lung carcinomas were analyzed for the distribution of hyaluronan (HA), using a biotinylated hyaluronan binding complex as an HA-specifi c probe. The normal pseudo-stratified columnar bronchial epithelium wa s either negative for HA or displayed a weak staining around the basal cells. The epithelia of serous and mucous bronchial glands were HA ne gative whereas the submucosal connective tissue was strongly positive. In metaplastic, dysplastic and carcinoma in site lesions the whole ep ithelium from basal to uppermost cells expressed HA on plasma membrane s. Epithelial HA was also found in squamous cell carcinomas, but not i n adenocarcinomas, carcinoid tumors or small cell carcinomas of the lu ng. Whereas epithelial HA was present in all lesions of the squamous c ell type, the staining intensity displayed great local variability in 50% of the cases with severe dysplasia, carcinoma in site and squamous cell carcinomas. In squamous cell carcinomas, such an irregular stain ing pattern was significantly associated with poor differentiation. Ou r results indicate that the expression of HA in different bronchial le sions and lung tumors is restricted to those showing squamous cell dif ferentiation, being absent from other types of lung carcinomas. The in crease of HA-depleted areas in poorly differentiated squamous cell car cinomas emphasizes the important role of HA in tumor differentiation, HA on carcinoma cell surface may influence tumor growth and metastatic behavior. (C) 1998 Wiley-Liss, Inc.