Endocrine Abstracts

Whilst the majority of differentiated thyroid cancers (DTC) have oncogenic mutations, a significant minority may be driven by the overexpression of proto-oncogenes. PTTG and PBF are proto-oncogenes which are induced in DTC, elicit tumours in xenograft models and interact in vitro, where PBF shuttles PTTG into the nucleus. However, the relative contributions of each gene to DTC has not been delineated. Here, we constructed a bi-transgenic murine model over-expressing b...

p53 is rarely mutated in thyroid papillary carcinomas, despite the thyroid being highly sensitive to ionising radiation. The pituitary tumor transforming gene binding factor (PBF) is a proto-oncogene overexpressed in thyroid cancer. Oncogenic levels of PBF result in cell transformation in vitro and tumourigenesis in vivo. By serendipity we have found that PBF interacts directly with the tumour suppressor protein p53. In light of these data we have investigated th...

PTTG is a multifunctional proto-oncogene overexpressed in thyroid cancers, which binds to p53 and modulates its function. PBF, a binding partner of PTTG, is also overexpressed in thyroid cancer and can transform cells independently of PTTG. Moreover, subcutaneous expression of PBF elicits large tumours in nude mice. Given the established role of ionising radiation in thyroid tumourigenesis, we investigated the relationship between PBF and the tumour suppressor protein p53. PBF...

Functional disruption of the tumour suppressor p53 has a critical role in promoting the development of most cancers. The proto-oncogenes PBF and PTTG1 both regulate p53 activity, but the relative contribution of each gene in influencing p53 function has not been delineated, especially in thyroid cancer where both proto-oncogenes are commonly overexpressed. To better understand the interplay between PTTG1, PBF and p53 in vivo, we examined p53 responses in primary thyrocytes cul...

Nodular thyroid disease is common and its pathogenesis remains poorly understood. Previously, we showed that thyroid-targeted overexpression of the proto-oncogene PTTG-Binding Factor (PBF) induced striking thyroid gland enlargement in transgenic mice (PBF-Tg)1. We have now investigated whether dietary factors influence goitrogenesis and the development of hyperplastic lesions in PBF-Tg mice. The mean weight of thyroids (5.8±0.9 mg; n=70) from 7 week old ...

PTTG binding factor (PBF) is a poorly characterised transforming gene that is overexpressed in thyroid tumours and inhibits the activity of the sodium iodide symporter (NIS) in vitro. Our recent investigations demonstrated that PBF mRNA expression was 2.6-fold higher in thyroid tissue excised from patients with multinodular goitres (MNG) than in normal thyroid tissue (n=25, P<0.01). We have now generated a murine transgenic model of targeted overexpres...

The human pituitary tumor transforming gene (hPTTG) is overexpressed in thyroid cancers; it induces genetic instability and propagates growth through the induction of growth factors. We set out to investigate the autocrine and paracrine pathways of interaction between hPTTG and epidermal growth factor (EGF), transforming growth factor-α (TGF-α) and insulin-like growth factor 1 (IGF1) in vitro and in vivo. Synchronised K1 papillary thyroid carcinoma cell...

Previously we showed that thyroid-targeted overexpression of the PTTG binding factor (PBF) induced significant goitrogenesis in transgenic mice (PBF-Tg). In 10 week old PBF-Tg mice thyroid weight was increased by 1.8±0.3-fold compared to wild-type (WT) controls (n=20, P<0.0001). We have now examined the long-term effects of PBF overexpression on thyroid gland weight and histology in aged PBF-Tg mice. Our study shows that the penetrance of increased thyro...