Endocrine Abstracts

We have previously shown Pituitary Tumor Transforming Gene (PTTG) and basic Fibroblast Growth Factor (FGF-2) to be upregulated in thyroid cancer. PTTG requires interaction with the protein PBF (PTTG Binding Factor) to stimulate FGF-2 secretion, and hence promote tumour angiogenesis and growth. We now report that PBF is also upregulated in hyperplastic and neoplastic thyroid tissues compared with normal thyroid (N=11) (2.6-fold in multinodular goitre (N=25, P=0.002), and 3.3-fo...

We have previously shown PTTG and PBF to be over-expressed in differentiated thyroid cancer and to be prognostic indicators for recurrence. Subsequently we reported PBF to be a transforming gene in vitro and tumourigenic in vivo. Since over-expression of PTTG results in the same findings, we examined whether PBF-induced tumourigenesis was an independent effect, or else a result of increased PTTG activity. Two HA-tagged mutants of PBF were generated, firstly subst...

The sodium iodide symporter (NIS) mediates the uptake of iodide into thyroid follicular cells. The pituitary tumor transforming gene (PTTG) is a multifunctional oncogene which stimulates expression of fibroblast growth factor-2 (FGF-2) via PTTG binding factor (PBF). PTTG and FGF-2 inhibit iodide uptake in rat thyroid FRTL5 cells and PTTG and PBF repress NIS mRNA expression and iodide uptake in primary human thyroid cultures. To determine whether this regulation is a direct tra...

VEGF exerts its effects by binding to two tyrosine kinase receptors, KDR and VEGFR1. KDR is critical for transmitting signals for proliferation and migration of endothelial cells but is also expressed in several non-endothelial cells, and is elevated in some human tumour cells. We investigated KDR expression in human thyroid epithelial cells in vitro and thyroid cancers compared with normal thyroid samples examined ex vivo. Expression of KDR was demonstrated usin...

We have previously shown PTTG binding factor (PBF) to be a transforming gene both in vitro and in vivo, forming colonies in soft agar and tumours in nude mice. We have found that along with PTTG, PBF is upregulated in thyroid cancer and is also a prognostic indicator for recurrence. As our cohort of thyroid cancers showed significantly reduced sodium iodide symporter (NIS) expression compared to normal thyroid (47% reduction, N=27, P=0.005), which was negatively ...

Angiogenesis is the rate-limiting step in tumour progression and metastatic spread. Both promoters and inhibitors of angiogenesis have been implicated in thyroid tumourigenesis. We have reported PTTG overexpression in thyroid and other cancers, and PTTG upregulation of the angiogenic factors FGF-2 and VEGF in vitro. To investigate whether PTTG also transactivates other downstream angiogenic effectors, we employed angiogenesis-specific cDNA arrays. Primary thyroid cells and PTT...

Chromosomal instability (CIN) is a common feature of many malignancies including papillary and follicular thyroid cancer. During mitosis, there are multiple stages which, if dysregulated, may result in CIN. One critical stage is the regulation of sister-chromatid separation at the metaphase-anaphase transition. Three key protein complexes regulate this process: separase, cohesins and securin (also known as pituitary tumor transforming gene). In vivo, most tumours studied demon...

PTTG has been implicated in the pathogenesis of pituitary, thyroid and other tumours. PBF was recently identified as a protein which interacts specifically with PTTG both in vitro and in vivo. PBF facilitates PTTG's nuclear localisation, and mediates its ability to transactivate basic fibroblast growth factor (FGF-2). We investigated PBF expression and function in vitro, and examined its relationship to PTTG action. Transient transfection of wild type PTTG induced a significan...

The sodium iodide symporter (NIS) mediates the uptake of iodide into thyroid follicular cells. The pituitary tumor transforming gene (PTTG) is a multifunctional oncogene which stimulates expression of fibroblast growth factor-2 (FGF-2) via the PTTG binding factor (PBF). PTTG, FGF-2 and PBF are all up-regulated in thyroid cancer. PTTG and FGF-2 inhibit NIS mRNA expression and iodide uptake in rat thyroid FRTL5 cells. We have shown previously that both PTTG and PBF repres...

Cancer reflects the progressive accumulation of genetic alterations and subsequent genetic instability of cells. Differentiated thyroid cancers exhibit aneuploidy; cytogenetic studies have demonstrated the importance of genetic instability in thyroid cancer development. Pituitary tumour transforming gene (PTTG), also known as securin, is a mitotic checkpoint protein which inhibits sister chromatid separation during mitosis. PTTG is highly expressed in many cancers and over-exp...