CBX3/HP1γ promotes tumor proliferation and predicts poor survival in hepatocellular carcinoma

HP1 gamma, encoded by CBX3, is associated with cancer progression and patient prognosis. However, the prognostic value and functions of CBX3/HP1 gamma in hepatocellular carcinoma (HCC) remain unclear. Here, we performed a bioinformatics analysis using the Oncomine, TCGA and Human Protein Atlas databases, the Kaplan-Meier plotter, and the UALCAN web-portal to explore the expression and prognostic significance of CBX3/HP1 gamma in patients with different cancers, including liver cancer. HCC tissues and microarrays containing 354 samples were examined using immunohistochemical staining, quantitative real-time polymerase chain reaction, and Western blotting. CBX3-overexpression HCC cell lines were tested in proliferation assays to determine the function of CBX3/HP1 gamma. We found that CBX3/HP1 gamma was upregulated in many cancers and was associated with poor prognosis. Our results also revealed that CBX3/HP1 gamma is elevated in HCC tissues and is associated with malignant clinicopathological characteristics. Kaplan-Meier and Cox regression analyses verified that high CBX3/HP1 gamma expression is an independent and significant prognostic factor for reduced overall survival in HCC patients. Moreover, in vitro functional assays showed that CBX3/HP1 gamma overexpression promotes HCC cell proliferation. These findings suggest that CBX3/HP1 gamma is an important oncogene in HCC that might act as a useful biomarker for prognosis and targeted therapy.