Cancer stem cells (CSCs) are thought to play important roles in carcinogenesis, recurrence, metastasis, and therapy-resistance. We have successfully induced cancer stem-like sphere cells (CSLCs) from hepatoma cell lines using a unique medium. Our induced CSLCs showed characteristic phenotypes of CSCs such as chemo- and immune-resistances. As a result of integrated analysis with RNA-seq, a RAB3B was identified as an up-regulated gene in both CSLCs in vitro and poor prognostic HCCs in vivo. Cells harboring mono-allelic RAB3B knock-out showed altered sphere formation and significantly lower chemoresistance compared to those of parental cells. The mono-allelic RAB3B knock-out cells also showed decreased PD-1 ligands in sphere induction medium than those in cells cultured with normal medium. Therefore, the up-regulation of RAB3B may plays important roles in CSLCs.
