Extracellular matrix protein 1 (ECM1) is a glycoprotein involved in a number of biologic processes. To investigate the expression of ECM1 in hepatocellular carcinoma (HCC) and determine its correlation with tumor progression and prognosis, the expression levels of ECM1 in three HCC and one normal liver cell lines, tumor, and corresponding adjacent tissues from 18 HCC patients were analyzed by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. Immunohistochemistry assay was used to determine the expression of ECM1 in HCC and corresponding paracarcinomatous tissues from 77 patients. The results of Western blotting were consistent with the results from RT-PCR analysis of ECM1 mRNA expression. Among the four cell lines, the expression level in HCCLM3, which with the highest metastatic potential, was significantly higher than that with lower (P < 0.05); while ECM1 expression was not detected in normal liver cell line. Expression level of ECM1 was significantly increased in HCC compared with adjacent and normal liver tissues (P < 0.05). Immunohistochemically, the expression of ECM1 in HCC was judged to be positive in 57 (74.0%) cases, significantly higher than that in corresponding paracarcinomatous tissues (P < 0.01), and it was associated with tumor size (P = 0.036), number of tumor nodules (P = 0.048), TNM stage (P = 0.029), and vascular invasion (P = 0.007). In particular, the expression of ECM1 was found to be an independent factor for predicting overall and disease-free survival of HCC. The expression level of ECM1 was associated with metastatic potential of HCC, and its abnormal expression may be used as a predictive factor of unfavorable prognosis and recurrence for HCC after surgery.

Metastasis remains one of the major challenges before hepatocellular carcinoma (HCC) is finally conquered. Estrogen has recently emerged as a protective factor in the development and progression of HCC, but whether and how it reduces metastasis of HCC remain to be elucidated. We conducted an in vivo highly metastatic rat HCC model in female Sprague-Dawley rats induced by diethylnitrosamine and N-nitrosomorpholine to examine the effects of estrogen on HCC metastasis. Moreover, female rats were randomly distributed into four groups: ovariectomy (OVX), sham operation, ovariectomy followed by 30 μg/kg body weight/day 17α-ethynylestradiol supplementation, and sexually intact control groups. Here, we show that, 60% lung metastasis was observed in the rats of OVX group, whereas 17-25% lung metastasis was found in rats of the other three groups. Furthermore, physiological doses of estrogen, no matter endogenous or exogenous, can suppress metastasis of HCC through decreasing interleukin-6 (IL-6) and hepatocyte growth factor (HGF) expression in the tumor microenvironment. In conclusion, the present study demonstrated that estrogen has the potential to inhibit lung metastasis from rat HCCs in vivo. Its mechanism of action may involve modulation of inflammatory tumor microenvironment by suppression of HGF and IL-6 production.

Osteopontin (OPN) is overexpressed in a variety of cancers including hepatocellular carcinoma (HCC), and is likely involved in the process of vasculogenic mimicry (VM) in some tumor cells. In this study, we explored whether OPN plays a role for VM in HCC. Metastatic MHCC97-H human HCC cells and nonmetastatic Hep3B human HCC cells were compared for their abilities to establish VM. Three dimensionalculture assays showed that MHCC97-H cells but not Hep3B cells were able to form the chord-like structure that represents VM. Real-time RT-PCR arrays were used to detect gene expression profiles of the two HCC cell lines in three-dimensional culture. PCR array analyses revealed the increased expression of OPN in MHCC97-H cells forming VM compared with Hep3B cells. Small interfering RNA was employed to investigate whether OPN knockdown could influence VM, and the expression of matrix metalloproteinase (MMP)-2, MMP-9 and urokinase-type plasminogen activator (uPA) in MHCC97-H cells. OPN knockdown resulted in a significant decrease in the ability of MHCC97-H cells to form VM, which was accompanied by the down-regulation of MMP-2 and uPA expression. Furthermore, human HCC tissue samples were studied by immunohistochemistry to analyze the correlations between VM and the expression of OPN, MMP-2 and uPA. There existed significant positive correlations between VM and the expression of OPN, MMP-2 and uPA in HCC tissue samples. In conclusion, OPN is required for VM in HCC cells, and its action may be associated with activation of MMP-2 and uPA. OPN-targeted therapeutics may be useful for patients with advanced HCC.