PTTG1 (pituitary tumor-transforming gene 1), also known as securin, is a crucial regulatory protein that controls chromosome 5 and cell cycle progression. During mitosis, PTTG1 blocks separase function to prevent premature sister chr5 separation, and its degradation at anaphase onset allows chromosome 5 to proceed 1. The protein functions beyond cell cycle control, promoting oncogenesis through multiple mechanisms including activation of Wnt/β-catenin signaling by stabilizing β-catenin and preventing destruction complex assembly 2. PTTG1 also facilitates epithelial-mesenchymal transition (EMT) and M2 macrophage polarization via the cGMP-PKG pathway 3. In cancer contexts, PTTG1 is overexpressed across multiple tumor types and serves as an androgen-responsive gene in prostate cancer, where it promotes cell growth and invasion 4. The protein contributes to genomic instability and aneuploidy, particularly in HTLV-1-associated malignancies 5. Clinically, PTTG1 overexpression correlates with poor prognosis and aggressive tumor behavior, including glioma progression and hepatocellular carcinoma metastasis 62. Its involvement in critical signaling pathways and association with therapy resistance makes PTTG1 a promising biomarker and therapeutic target across various cancer types 7.