alpha 6 integrin expression in esophageal carcinoma

One of the genes that the authors have isolated by a differential display o f hepatocellular carcinoma compared to adjacent liver is the alpha 6 integr in. alpha 6 integrin is the major adhesion receptor for laminin and is sugg ested to be involved in tumor cell invasion and metastasis. To our knowledg e, however, there are no reports on alpha 6 integrin expression in esophage al carcinoma. We thus conducted a study to determine its clinicopathologic significance in human esophageal carcinoma. The tumor/normal (T/N) ratio of alpha 6 integrin expression was calculated by Northern hybridization in 45 cases of esophageal carcinoma. In selected cases the expression of the alp ha 6 integrin variants A and B was also investigated by reverse transcripta se-polymerase: chain reaction, and immunostaining for alpha 6 integrin was performed. The expression levels of alpha 6 integrin mRNA in the tumor tiss ue were greater than those of the corresponding normal tissue in 39 of 45 c ases (87%). The overexpression of alpha 6 integrin was also recognized by i mmunostaining. Fifteen cases with a high T/N ratio demonstrated a deeper in vasion into the esophageal wall than the 30 cases with a low T/N ratio. Alt hough there was no significant difference, the 15 cases with a high T/N rat io had a tendency for a worse prognosis. The ratio of the two variants (alp ha 6A/alpha 6B) did not show any relationship to survival. The findings imp ly that alpha 6 integrin is overexpressed in human esophageal carcinomas an d that alpha 6 integrin may play an important role in esophageal tumor inva sion.