Decreased Expression of Inhibitor of Growth 4 Correlated with Poor Prognosis of Hepatocellular Carcinoma

Objective: Inhibitor of growth 4 (ING4) is a candidate tumor suppressor that plays an important role in tumor growth and angiogenesis. Here, we examined the expression of ING4 in hepatocellular carcinoma (HCC) tissues and analyzed its correlation with the progression of HCC. Methods: Specimens from 136 HCC patients were determined immunohistochemically for ING4 expression. The correlation of ING4 levels with clinicopathologic variables, prognosis, and metastatic potential was analyzed. Among the 136 cases, 36 paired HCC and paracarcinomatous liver tissue specimens were analyzed for ING4 expression levels by real-time quantitative reverse transcription-PCR and Western blotting. MVD was determined by CD34 immunostaining to test whether it correlated with ING4 protein expression level. Results: The ING4 mRNA and protein levels were significantly lower in HCC than paracarcinomatous liver tissue from both real-time quantitative reverse transcription-PCR and Western blotting (P = 0.039 and 0.01.2, respectively). Importantly, the ING4 protein level correlated with the Edmondson-Steiner grade (P = 0.035), vein invasion (P = 0.015), and microvessel density (P = 0.005). Survival and metastasis analysis indicated that HCC patients with lower ING4 expression had poorer overall survival and disease-free survival than those with high expression (P = 0.0001 and 0.0065; respectively). Multivariable Cox regression analysis revealed that the ING4 expression level was an independent factor for prognosis (hazard risk, 9.63; P = 0.001). Conclusions: ING4 expression is down-regulated in HCC tissues. ING4 expression level correlates with prognosis and metastatic potential, which suggests that ING4 is a candidate prognostic marker of HCC. (Cancer Epidemiol Biomarkers Prev 2009;18(2): 409-16)