Gene expression of human squamous cell carcinoma antigens 1 and 2 in humancell lines

The squamous cell carcinoma antigen (SCCA) serves as a serological marker f or squamous cell carcinomas. Molecular cloning of the SCCA genomic region h as revealed the presence of two tandemly arrayed genes, SCCA1 and SCCA2. SC CA1 is a papain-like cysteine proteinase inhibitor, while SCCA2 is a chymot rypsin-like serine proteinase inhibitor. Little is known concerning how exp ression of the SCCA1 and SCCA2 genes is regulated in human cell lines. The purpose of this study was to determine whether the SCCA1 gene or SCCA2 gene is more strongly expressed in human cell lines. Squamous cell carcinoma ce ll lines secreted respectively 4 times and 50 times as much SCCA proteins i nto medium as normal human keratinocyte and non-squamous cell carcinoma cel l lines, as measured by enzyme-linked immunosorbent assay. Quantitative RT- PCR ELISA digoxigenin-labeling assay demonstrated that SCCA1 mRNA expressio n in squamous cell carcinoma cell lines was respectively 2.8 times and 42 t imes that in keratinocyte and non-squamous cell carcinoma cell lines. The r atio of SCCA1 to SCCA2 mRNA expression differed distinctly among squamous c ell carcinoma, keratinocyte and non-squamous cell carcinoma cell lines (2.8 , squamous; 24.1, keratinocyte; 11.0, non-squamous). These findings suggest that SCCA1 is mainly expressed in squamous cell carcinoma, keratinocyte an d non-squamous cell carcinoma cell lines and that the ratio of SCCA1 to SCC A2 expression might be a novel marker for the detection of squamous cell ca rcinoma.