RESEARCH ARTICLE Cancer stem-like sphere ce e

Hepatocellular carcinoma (HCC) is the sixth most com-mon and the third most deadly cancer worldwide affecting 1 million individuals annually [1]. Most potentially cura-tive therapies for HCC such as surgical resection, trans-plantation and ablation therapy are of limited efficacy in advanced stages, and the recurrence rate after these treat-ments is 40 to 80 % within 5 years [2,3]. Various types of post-operative therapies, including transarterial lipiodol chemoembolization, systemic or focal chemotherapy, α-interferon, adoptive immunotherapy, and oral acyclic ret-inoid acid have been used in HCC patients following cura-tive treatment. However, the benefits of adjuvant therapy have not been definitively demonstrated. Therefore, new adequate adjuvant therapy is needed to improve survival. Recent research has focused on cancer stem cells (CSCs) to increase our understanding of the characteristics of can-cers including HCC. CSCs possess stem cell properties such as a self-renewal capacity, tumor-initiating ability, higher tumorigenicity, metastatic potential, and chemoresistance [4]. To investigate CSC properties such as tumor initiatio