Expression of tenascin and of the ED-B containing oncofetal fibronectin isoform in human cancer

Tenascin (TN) and the oncofetal ED-B containing fibronectin isoform (B-FN) have been reported to be stromal markers of a number of malignancies. Here we report on studies of the distribution of TN and B-FN in normal adult tissues and in benign and malignant tumors, as well as on the levels of the B-FN mRNA in cultured fetal and non-fetal human fibroblasts originating from different tissues. B-FN has an extremely restricted distribution in normal adult tissues, is not expressed in benign tumors, but is greatly expressed in a high percentage of malignant tumors. On the contrary, human TN in normal adult tissues is less restricted than what has previously been reported and it is largely expressed in a number of both benign and malignant tumors. Moreover, we observed a great variability in the relative amount of B-FN mRNA among the 17 normal human fibroblast cell lines tested. We found very low levels in non-fetal skin fibroblasts and higher levels in fetal lung fibroblasts. We also found differences in the relative amounts of B-FN mRNA between fibroblast cell lines originating from the skin and the lung of the same subject.