Shi Wu Zhang

Expression and Functional Significance of Twist1 in Hepatocellular Carcinoma: Its Role in Vasculogenic Mimicry

The up‐regulation and nuclear relocation of epithelial‐mesenchymal transition (EMT) regulator Twist1 have been implicated in the tumor invasion and metastasis of human hepatocellular carcinoma (HCC). The term vasculogenic mimicry (VM) refers to the unique capability of aggressive tumor cells to mimic the pattern of embryonic vasculogenic networks. However, the relationship between Twist1 and VM formation is not clear. In this study, we explored HCC as a VM and EMT model in order to investigate the role of Twist1 in VM formation. We first examined the expression of Twist1 in human HCC samples and cell lines and found that Twist1 was frequently overexpressed in the nuclear relocation occurring in VM‐positive HCCs (13/18 [72%]). Twist1 nuclear expression was likewise significantly associated with VM formation. Clinicopathological analysis revealed that both VM and Twist1 nuclear expressions present shorter survival durations than those without expression. We consistently demonstrated that an overexpression of Twist1 significantly enhanced cell motility, invasiveness, and VM formation in an HepG2 cell. Conversely, a knockdown of Twist1 by the short hairpin RNA approach remarkably reduced Bel7402 cell migration, invasion, and VM formation. Using chromatin immunoprecipitation, we also showed that Twist1 binds to the vascular endothelial (VE)‐cadherin promoter and enhances its activity in a transactivation assay. Conclusion: The results of this study indicate that Twist1 induces HCC cell plasticity in VM cells more through the suppression of E‐cadherin expression and the induction of VE‐cadherin up‐regulation than through the VM pattern in vivo and in a three‐dimensional in vitro system. Our findings also demonstrate a novel cogitation in cancer stem‐like cell differentiation and that related molecular pathways may be used as novel therapeutic targets for the inhibition of HCC angiogenesis and metastasis. (HEPATOLOGY 2009.)

Functional significance of VEGF-a in human ovarian carcinoma: Role in vasculogenic mimicry

Ovarian cancer is a silent killer, and shows early extensive tumor invasion and peritoneal metastasis. The microcirculation of most tumors includes cooperation of pre-existing vessels, intussusceptive microvascular growth, postnatal vasculogenesis, glomeruloid angiogenesis, and vasculogenic mimicry (VM). VM is critical for a tumor blood supply and is asscociated with aggressive features and metastasis. Our studies highlight the plasticity of aggressive human ovarian carcinoma cells and call into question the underlying significance of their ability to form VM in vitro induced by VEGF-a. These studies also show their clinicalpathological features of the cancers with human Paraffin-embedded tumor tissue samples. Results show that the process: VEGF-a→EphA2→MMPs→VM is the main pathway for VM formation and VEGF-a appears to play an important role in the formation of VM based on our in vitro assays and clinical immunohistochemical analyses. VM-targeting strategies for ovarian cancer include anti-VEGF-a treatment, knocking down the EphA2 gene and using antibodies against human MMPs if the tumor is VM positive. This strategy may be of significant value in laying the foundation for a more explicit anti-tumor angiogenesis therapy.