Role of histone deacetylase expression in intrahepatic cholangiocarcinoma

Histone deacetylase (HDAC) plays an important role in chromatin remodeling and gene expression, and in regulating cell cycle progression and differentiation. Furthermore, hypoxic conditions in the malignant tumor enhance HDAC function and increased HDAC activity is closely involved in worse malignant behavior through hypoxia inducible factor (HIF) activation. The aim of this study was to elucidate the correlation between HDAC expression and tumor malignant behavior including HIF-1α expression in intrahepatic cholangiocarcinoma (IHCC).

Thirty-five patients with IHCC who underwent hepatic resection were evaluated. HDAC1 and HIF-1α expressions were determined immunohistochemically, and the patients were divided into 2 groups: the HDAC1 positive group (n = 21) and the HDAC1 negative group (n = 14). Clinicopathologic variables including HIF-1α expression were compared between the 2 groups.

HDAC1 expression correlated significantly with higher stage carcinoma, lymph node metastasis, and vascular invasion. The prognosis in the HDAC1 positive group was poorer than in the HDAC1 negative group (5-year survival: 78% vs 8%, P = .001). Furthermore, disease free survival rate in the HDAC1 positive group had significantly worse than that in the HDAC1 negative group (P = .0003). In the multivariate analysis, HDAC1 positive expression was identified as the only independent prognostic factor for disease free survival (Hazard Ratio: 7.194, P = .0018). Furthermore, there was a significant correlation between HDAC1 expression and HIF-1α expression (P = .007).

These findings suggested that HDAC1 positive expression was a potential new prognostic indicator of IHCC, and a possible promising molecular target through the regulation of HIF-1α.