PTTG1 and ovarian cancer: PTTG silencing using siRNA on xenograft tumors from an ovarian cancer cell line and hepatocellular carcinoma cell line reduced both the size and incidence of tumor burden; however, incomplete silencing of PTTG led to a reduction of tumor burden, while complete silencing showed nearly complete eradication of tumors, indicating that PTTG expression impacts tumor formation and tumor growth [19,21].