Rapid screening of specific changes in mRNA in thyroid carcinomas by sequence specific-differential display: Decreased expression of acid ceramidase mRNA in malignant and benign thyroid tumors

Sequence specific-differential display (SS-DD) is a powerful method for scr eening significant changes in gene expression between normal and malignant tissues. Using this method, we detected 3 genes for which the expression is much decreased in thyroid tumors. After sub-cloning and sequencing analysi s, one of the genes was revealed to be acid ceramidase (AC). The expression of AC in normal thyroids and thyroid tumors was examined by semi-quantitat ive reverse-transcription-polymerase-chain-reaction (RT-PCR). Obvious decre ases in the expression of AC mRNA were observed in 5/6 follicular adenomas, 2/2 adenomatous goiters, 3/6 papillary carcinomas and 1/2 follicular carci nomas. To confirm this result, real-time quantitative PCR analysis (Taq-Man PCR) was carried out. The relative expression level of AC mRNA compared wi th that of GAPDH mRNA was reduced in follicular adenomas, follicular carcin omas, and papillary carcinomas. Further, the expression of AC mRNA was extr emely reduced in 2 anaplastic carcinomas. These results suggest a possible relationship between thyroid tumorigenesis and the expression of AC mRNA. M oreover, the increased expression of AC mRNA in normal thyroid tissues sugg ests some fundamental roles of AC in thyroid function. (C) 1999 Wiley-Liss, Inc.