Androgen receptor expression in C-cells and in medullary thyroid carcinoma.

Recent studies have shown a higher incidence of C-cell hyperplasia (CCH) in men compared with women in postmortem thyroid tissues. We postulated that the expression of androgen receptor (AR) protein may, in part, explain the differences. To test this hypothesis, we examined thyroid tissue from 27 consecutive autopsy cases for the presence of CCH (defined as >50 C-cells/x100 magnification in three fields) and for AR expression in autopsy cases and in 43 medullary thyroid carcinomas (MTCs) from patients with sporadic and familial disease as well as two multiple endocrine neoplasia type 2A patients with only CCH. CCH was present in 8 of 20 males (40%) and in 1 of 7 females (14%) at autopsy. AR protein was detected in most surgically resected thyroids with MTC and CCH (80%), but in only 25% of autopsy thyroids, probably reflecting postmortem degradation of the receptor protein. Reverse transcriptase polymerase chain reaction confirmed the presence of AR mRNA in MTC and in papillary thyroid carcinomas. These results support the observation that CCH is more common in postmortem thyroids of males and suggest that the presence of AR with higher circulating levels of androgens may contribute to the higher incidence of CCH in men.