Role of piuitary tumour transforming gene 1 in medullary thyroid carcinoma

Pituitary tumour transforming gene 1 (PTTG1) is over-expressed in a variety of endocrine-related tumors. We investigated PTTG1 expression in human C-cell hyperplasia (CCH), human medullary thyroid carcinoma (MTC) and in the human MTC cell line, TT. PTTG1 expression was significantly higher (P<0.01) in CCH (threefold), in papillary thyroid cancer and in MTC (fivefold) than in normal thyroid, and in MTC lymph-node metastases as compared to primary lesions (approximately twofold; P<0.05). PTTG1 mRNA and protein correlated with tumor diameter and TNM status (P<0.05). In TT cells, PTTG1 silencing did not completely block DNA synthesis, but significantly reduced [3H]Thymidine incorporation (~50%; P<0.01) for up to 3 days. Furthermore, PTTG1 overexpression significantly decreased cell proliferation, lasting for at least 3 days (30–60%; P