Cytoplasmic expression of CD133 is an important risk factor for overall survival in hepatocellular carcinoma

CD133 antigen has been used to identify cancer stem cells in several solid tumor types, including hepatocellular carcinomas (HCCs). The aim of this study was to investigate whether the expression and subcellular localization of CD133 correlated with the clinicopathological factors, recurrence, and survival in HCC patients. Tissue specimens from 136 HCC patients who underwent curative primary hepatectomy between 2000 and 2005 were collected and immunohistochemically analyzed for CD133 expression. Positive immunohistochemical results and subcellular localization of CD133 were determined, and the correlation between CD133 expression and clinicopathological factors of HCC patients were evaluated. CD133-positive tumor cells were observed in 30 (22.1%) cases. Cytoplasmic and membranous expressions were observed in 22 (16.2%) and 20 (14.7%) of the CD133-positive cases, respectively. Positive cytoplasmic expression of CD133 was found to be associated with the overall survival of HCC patients, especially in stage III and IVA HCC patients (p=0.0092). Univariate analysis revealed that pre-operative serum albumin, alpha-fetoprotein (AFP) levels, tumor size, portal venous invasion, and cytoplasmic CD133 expression were important risk factors in HCC. Multivariate analysis revealed that among the factors related to tumor aggressiveness, cytoplasmic expression of CD133 showed the most significant association with overall survival, although the difference was not statistically significant (P=0.0681). Cytoplasmic expression of CD133 was a significant risk factor for the overall survival of HCC patients. Patients with stage III and IVA HCC showing positive cytoplasmic expression of CD133 are more likely to have a worse prognosis.