Overexpression of SCC antigen and cyclins in an adenoid squamous carcinomacell line derived from the maxillary sinus

Squamous cell carcinoma antigen (SCC-Ag) is produced by the two almost iden tical, tandemly arrayed genes, SCCA1 and SCCA2. In this study, we investiga ted the mechanism of increased expression of SCC-Ag in a eel line SCCMM der ived from an aggressive adenoid SCC with high titer of SCC-Ag in the patien t serum. The differential polymerase chain reaction using specific primers for SCCA1 and SCCA2 revealed no gene amplification in SCCMM. However, RT-PC R demonstrated that levels of SCCA1 and SCCA2 mRNAs in SCCMM were 80- and 1 20-fold higher than those in CaSki as a reference SCC cell, respectively. W estern blot analysis showed that the levels of these two SCC-Ag proteins in SCCMM were 15-fold higher than those in CaSki, suggesting chat expression of the SCC-Ag in SCCMM was controlled at both the transcriptional and post- transcriptional levels. To investigate highly malignant character of SCCMM, expression of cell cycle regulatory proteins was investigated by Western b lotting. Cyclin E and cyclin B1 were expressed at approximately 100-fold hi gher levels in SCCMM than in CaSki, but Cip/Kip cyclin-dependent kinase inh ibitors (CDKIs) were expressed at low levels and p16 and p19 ink4 CDKIs wer e not detected. These results suggest that the aggressive growth of SCCMM i s due, at least in part, to large increases in cyclin E and cyclin B1 expre ssion with low levels of CDKIs.