PBF

Pituitary tumor-transforming gene 1 protein-interacting protein (PTTG1), also known as PTTG1-binding factor (PBF), is a poorly characterised protein that in humans is encoded by the PTTG1IP gene located within the chromosomal region 21q22.3. Although PTTG1IP is ubiquitously expressed in normal human tissues, its exact function remains elusive. It has been shown to directly interact with the human securin and proto-oncogene, PTTG1, thus facilitating its nuclear translocation and the subsequent transcriptional activation of basic fibroblast growth factor (bFGF) by PTTG1. Further evidence suggests that PTTG1IP may have a direct role in cancer. Initially, PTTG1IP expression was found to be higher in pituitary tumours compared with normal pituitary tissue. In particular, PTTG1IP has been shown to regulate thyroid cell growth, with overexpression resulting in hyperplasia and the formation of lesions within the thyroid gland. PTTG1IP expression has also been independently associated with tumour recurrence and subcutaneous expression results in tumour formation in nude mice. PTTG1IP is also implicated in breast cancer.