Objectives: To investigate the prognostic significance of Omi/HtrA2 expression, and the correlation between Omi/HtrA2 and Hypoxia-inducible factor (HIF)-1α in primary hepatocellular carcinoma cells.
Methods: The expression of HIF-1α and Omi/HtrA2 in 43 cases of hepatic carcinoma tissues were detected immunohistochemically. Follow-up data were obtained to perform the Kaplan-Meier survival analysis. The change of Omi/HtrA2 expression in HepG2 cell was measured after HIF-1α expression of HepG2 in vitro was regulated by Tet-on expression system.
Results: Omi/HtrA2 expression was correlated with lymph node metastasis and recurring within liver during 2 years. Statistical analysis estimation showed the cumulative survival rate of post-hepatectomy for the patients with the positive expression of Omi/HtrA2 was higher than that for other patients with the negative expression of Omi/HtrA2 (χ(2) = 6.13, P = 0.013). In the common paraffin-embedded specimen of hepatocellular carcinoma, most of the samples showing negative or weak positive HIF-1α immunopositivity showed moderate positive or strong positive Omi/HtrA2 immunopositivity, while most of the samples showing moderate positive or strong positive HIF-1α immunopositivity showed negative or weak positive Omi/HtrA2 immunopositivity. The mRNA expression intensity of Omi/HtrA2 was decreasing with the HIF-1α expression increasing, and the difference was statistically significant(F = 106.766, P < 0.01).
Conclusions: Omi/HtrA2 may be an important prognostic marker for primary hepatocellular carcinoma. Omi/HtrA2 expression is reversely correlated with HIF-1α expression in hepatocellular carcinoma. During the apoptotic process Omi/HtrA2 participating in hepatocellular carcinoma cells, HIF-1α is involved in the controlling and regulating of Omi/HtrA2 expression.