Oncogenic and prognostic role of CKAP2L in hepatocellular carcinoma

Cytoskeleton-associated protein 2-like (CKAP2L) exerts crucial function in the cell-cycle progression and mitotic spindle formation of neural stem/progenitor cells. However, in hepatocellular carcinoma (HCC), the expression pattern, clinical significance and biologic role of CKAP2L remain unexplored. We analysed The Cancer Genome Atlas (TCGA) database and found that CKAP2L was dramatically upregulated in HCC tissues at the mRNA level compared to adjacent tissues, which was validated in 48 paired HCC and para-tumor tissues using quantitative Real-Time PCR (qRT-PCR). Immunohistochemical analysis of tissue microarray revealed that CKAP2L was also significantly overexpressed at the protein level. Further clinical and survival analysis of the TCGA cohort revealed that increased CKAP2L expression was strongly associated with reduced overall survival. We further validated that higher CKAP2L protein expression was associated with worse prognosis in the Peking Union Medical College Hospital (PUMCH) cohort. Univariate and multivariate COX regression analyses in the TCGA and PUMCH cohort suggested that CKAP2L overexpression was an independent risk factor for poor prognosis in HCC patients. Then, we validated that CKAP2L silencing inhibited HCC cell proliferation, migration, and invasion abilities. Knockdown of CKAP2L in Huh7 cells suppressed the growth of xenograft tumors in vivo. Furthermore, qRT-PCR and western blotting results demonstrated that the expression of Class I Phosphoinositide 3-Kinase PIK3CA/p110α and PIK3CB/p110β isoforms reduced obviously in Huh7 cells after depleting CKAP2L. This study demonstrated for the first time that high CKAP2L expression in HCC tissues is significantly correlated with poor prognosis in HCC patients and greatly facilitate the malignancy of HCC, thus providing a new prognostic biomarker and potential therapeutic target.