Overexpression of Osteopontin is Associated with Intrahepatic Metastasis, Early Recurrence, and Poorer Prognosis of Surgically Resected Hepatocellular Carcinoma

Background: Intrahepatic metastasis via portal vein spread is an important feature and a crucial unfavorable prognostic factor of hepatocellular carcinoma (HCC). To identify the molecular factors for tumor progression, the authors used differential display (DD) to analyze aberrant gene expression in HCC. The goal of the current study was to elucidate the clinicopathologic and prognostic significance of osteopontin (OPN) in HCC progression.

Methods: OPN mRNA levels, which were increased preferentially in HCC in a DD assay and verified with Northern blotting, were measured in 240 surgically removed, unifocal, primary HCCs using the reverse transcription-polymerase chain reaction at the exponential phase. OPN mRNA expression was correlated with clinicopathologic features, particularly portal vein invasion, early tumor recurrence, and prognosis.

Results: Osteopontin mRNA was overexpressed in 133 tumors (55%). The OPN overexpression was associated closely with alpha-fetoprotein elevation (P = 0.001), p53 mutation (P = 0.021), larger tumors (P = 0.002), high-grade HCC (P < 0.001), late-stage HCC (P < 0.001), early tumor recurrence and/or metastasis (P = 0.003), and a lower 10-year survival rate (P = 0.00013). Multivariate analysis revealed that tumor stage and early tumor recurrence were crucial prognostic factors. In early-stage HCC, which has no vascular invasion and a lower early tumor recurrence than late-stage HCC, OPN mRNA overexpression predicted a higher early recurrence rate (P = 0.003).

Conclusions: OPN mRNA overexpression was correlated closely with high-grade, late-stage, and early tumor recurrence, which lead to poorer prognosis. Osteopontin overexpression might serve as an unfavorable prognostic factor and a useful marker for predicting early recurrence in early-stage HCC.