Expression of tenascin in tumors of the esophagus, small intestine and colorectum. An immunohistochemical study.

Tenascin, a large glycoprotein of the extracellular matrix, is involved in cell proliferation, differentiation, and migration during embryogenesis. In adult tissue, it is expressed only in certain areas. However, it gains importance again in proliferative processes such as wound healing and especially in tumor development. We examined paraffin-embedded specimens of 25 patients with a squamous cell carcinoma of the esophagus, 5 patients with an adenocarcinoma of the small intestine, 4 patients with a carcinoid tumor of the small intestine, and 49 patients with an adenocarcinoma of the colorectum. Immunohistochemical staining was performed by the use of a monoclonal antibody against human tenascin and the avidin-biotin-complex technique. Amino-Ethylcarbazol served as a chromogen. We investigated the distribution of tenascin in tumors, normal tissue, and lymph node metastases and compared it to tumor grading and TNM-classification. We found a uniform pattern of tenascin expression in all tumors and lymph node metastases examined in the gastrointestinal tract. One pattern was characterized by an immunoreaction near the basement membrane in well-differentiated areas and the other showed a diffuse, network-like expression in poorly differentiated areas with abundant stroma. There was a more intensive staining of the surrounding stroma near tumor cells invading into the submucosa or muscularis propria. It was even possible to detect small early carcinomas as well as small tumor cell populations in and around the lymph nodes by a strong immunostaining of the surrounding stroma. But we could not find any correlation of the tenascin expression patterns in comparison to the tumor grading and TNM-classification.