Novel forms of squamous cell carcinoma antigen transcripts produced by alternative splicing

Squamous cell carcinoma antigen (SCCA) is a member of the ovalbumin serine protease inhibitor family, and the serum level of SCCA is a tumor marker of squamous cell carcinoma. Reverse transcription (RT)-PCR of the squamous ce ll carcinoma cell line showed the existence of a 156 base shorter transcrip t compared with that of SCCA1 cDNA. By inverse PCR. we cloned the full leng th cDNA of this SCCA (SCCA1b). Sequence analysis of the complete 1541 bp SC CA1b cDNA showed that it coded for 338 amino acids and had no typical signa l sequence in the NH2 terminus. The cDNA was expressed in Escherichia coli and the product was detected using Western blotting with antibodies against SCCA. Furthermore, RT-PCR of the full coding region of SCCA2 cDNA from can cer tissue showed the existence of a 63 base short transcript (SCCA2b). A c omparison of SCCA1b and SCCA2b cDNA with the SCCA1 and SCCA2 genes showed t hat these messages were derived from each gene by an alternative splicing m echanism. (C) 2001 Elsevier Science B.V. All rights reserved.