Detection of large molecular weight cytokeratin 8 as carrier protein of CA19-9 in non-small-cell lung cancer cell lines.

It has been reported that cytokeratin 8 (CK8) is expressed in all non-small-cell lung cancers (NSCLC). We hypothesized that antigenic changes of CK8 may occur in some NSCLC cell lines. To prove this, Western immunoblot analysis using anti-human CK8 monoclonal antibodies as well as immunohistological staining of CK8 were performed in NSCLC cell lines. As a result, CK8 which had a higher molecular weight than recombinant CK8 was demonstrated in two of eight NSCLC cell lines. In addition, this CK8 contained antigenic epitopes of CA19-9. This CK8 with higher molecular weight, may have played a role in the process of invasion or metastasis of NSCLC.