Abstract: Background and purpose: Kinesin superfamily (KIF) is a group of classic molecular motors that regulate microtubule movement and participate in cell motility, mitosis, intracellular transportation and carcinogenesis. KIF21B, a member of KIF and the regulator of microtubule dynamic system, has not been reported in tumor. The study aimed to investigate the correlation between KIF21B expression in hepatocellular carcinoma (HCC) and the pathological features of patients with HCC, and its effect on prognosis. Methods: Data on the differential expression of KIF21B in patients with HCC from The Cancer Genome Atlas (TCGA) database were analyzed. Real-time fluorescence quantitative polymerase chain reaction (RTFQ-PCR) was used to detect the KIF21B mRNA expression in HCC cell lines and hepatocyte lines. To validate the TCGA database results, immunohistochemical analysis was used to evaluate the differential expression of KIF21B in HCC tissues and tumor adjacent tissues from 116 patients with HCC who underwent surgery in Gansu Provincial Hospital from March 2014 to June 2018, and this study further investigated the correlation between KIF21B expression and pathological features of the patient with HCC. The COX and Kaplan-Meier methods were used to assess prognostic significance. Results: Immunohistochemistry results were consistent with the TCGA analysis showing increased KIF21B expression levels in HCC tissues compared with adjacent normal tissues, and the correlation between KIF21B expression and TNM stage, hepatitis B surface antigen (HBsAg) and vascular invasion was obvious (P<0.05). The expression of KIF21B was obviously higher in HCC cell lines compared with hepatocyte lines (P<0.01). Kaplan-Meier analysis showed that the 5-year survival rate was significantly higher in lower KIF21B expression group compared with higher KIF21B expression group (P<0.05). COX proportional hazards regression analysis showed that KIF21B was an independent factor affecting the prognosis of HCC. Conclusion: KIF21B expression is significantly higher in HCC tissues compared with normal adjacent tissues, which is closely related to prognosis, and may be involved in development of HCC.

Key words: Hepatocellular carcinoma, Microtubule, Kinesin superfamily, KIF21B, Prognosis