Downregulation of nucleolar and spindle-associated protein 1 expression suppresses liver cancer cell function

The aim of the present study was to determine the role of nucleolar and spindle-associated protein 1 (NuSAP1) in human liver cancer. NuSAP1 expression was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blotting and immunohistochemistry in hepatocellular carcinoma (HCC) and adjacent tissues. The expression of NuSAP1 gene was detected by RT-qPCR in liver cancer cell lines. Expression information for NuSAP1 was determined using the UALCAN and Oncomine databases. The Kaplan-Meier plotter and The Cancer Genome Atlas databases were used to obtain overall survival data for liver cancer. Liver cancer cell lines HepG2 and Huh-7 were transfected with lentiviral particles to silence the endogenous NuSAP1 gene expression. RT-qPCR and western blotting were performed to confirm the silencing efficiency. Cell Counting Kit-8 was used to estimate the effects of NuSAP1 silencing on HepG2 and Huh-7 cell proliferation. Cell cycle and apoptosis analyses were performed using flow cytometry. Cell invasion was assessed using the Transwell assay with microscopy imaging. The results revealed that the NuSAP1 expression levels in HCC tissues were significantly increased compared with the adjacent tissues. The survival time of patients with HCC with a high NuSAP1 expression was markedly decreased compared with that of patients with HCC with a low expression level of NuSAP1. Functional studies revealed that NuSAP1 silencing significantly reduced HepG2 and Huh-7 cell proliferation and invasion. Increased apoptosis and cell cycle arrest at the G1 phase were observed following NuSAP1 knockdown. NuSAP1 silencing significantly inhibited the mRNA expression of DNA methyltransferase but not glioma-associated oncogene. NuSAP1 contributed to liver cancer development by reducing apoptosis and promoting cell cycle progression. The abnormal expression level of NuSAP1 may serve a role in promoting liver cancer progression.