Distribution of tenascin in oral premalignant lesions and squamous cell carcinoma.

The distribution of the extracellular matrix (ECM) protein tenascin (Tn) was studied in oral premalignant lesions and squamous cell carcinoma by using the monoclonal antibody (Mab) 143DB7. In normal buccal and palatal mucosa, in ventral tongue, in floor of mouth and in gingiva, immunoreaction for Tn was seen to be distributed as a continuous thin, delicate line merely in the basement membrane region. Hyperkeratosis without dysplasia showed a distinct zone of enhanced Tn immunoreactivity immediately beneath the epithelium. In dysplasias of various degree, enhancement of the stromal Tn content could be observed, being most conspicuous in carcinoma in situ lesions. In most invasive carcinoma cases the Tn immunoreactivity was intense, extending deeply into the underlying stroma. In such lesions Tn-reaction often covered the total stroma. Notably, the strongest immunoreaction was seen at the advancing edges of the tumor. The triggering factor for stromal Tn enhancement seems to be of epithelial origin. The enhanced expression of Tn suggests that Tn plays a role in organizing and remodelling the stroma to support active epithelial proliferation and migration. However, it also seems that inflammation is associated with Tn expressions.