Tenascin-C in serum: a questionable tumor marker.

In normal adult tissue tenascin-C (TN-C) is usually expressed at low levels. However, it is strongly induced in many tumors as well as in other pathological conditions often associated with inflammation. To evaluate the diagnostic significance of TN-C, we established a sensitive sandwich ELISA to determine TN-C levels in serum. Furthermore, we investigated the distribution of TN-C variants in serum and found the large TN-C isoforms to be predominant. We measured TN-C in sera from 15 healthy persons, 75 tumor patients and 84 patients selected due to their elevated levels of the acute-phase protein C-reactive protein (CRP), which is a very specific marker for infection and inflammation. It was found that sera from cancer patients can have elevated TN-C levels; however, the increase was more pronounced in persons with high levels of CRP. There appeared to be a correlation of TN-C levels with the levels of CRP. In view of these facts, the diagnostic value of TN-C levels in serum as a potential tumor marker seems to be questionable, since our data show that TN-C levels can be elevated as a consequence of infection and inflammation.