BLOCK OF C-MYC EXPRESSION BY ANTISENSE OLIGONUCLEOTIDES INHIBITS PROLIFERATION OF HUMAN THYROID-CARCINOMA CELL-LINES

Although elevated c-myc expression seems to be related to an unfavorab le prognosis of human thyroid neoplasias, the role of c-myc overexpres sion in the process of thyroid carcinogenesis is still unknown, We ana lyzed C-myc expression in 7 human thyroid carcinoma cell lines, origin ating from different histotypes, and in 50 fresh thyroid tumors and fo und a higher level of c-myc mRNA in all the thyroid carcinoma cell lin es and in several fresh thyroid tumors compared with normal thyroid, T he highest increases occurred in the most malignant cell lines and in undifferentiated human thyroid carcinomas, The block of c-MYC protein synthesis with myc-specific antisense oligonucleotides reduced the gro wth rate of the thyroid carcinoma cell lines significantly, Our result s indicate that c-myc overexpression plays a critical role in the grow th of thyroid cancer cells, which supports the hypothesis that the myc proto-oncogene might be involved in the neoplastic progression of thy roid carcinogenesis.