Inhibition of tumor vasculogenic mimicry and prolongation of host survival in highly aggressive gallbladder cancers by norcantharidin via blocking the ephrin type a receptor 2/focal adhesion kinase/paxillin signaling pathway.

Vasculogenic mimicry (VM) is a newly-defined tumor microcirculation pattern in highly aggressive malignant tumors. We recently reported tumor growth and VM formation of gallbladder cancers through the contribution of the ephrin type a receptor 2 (EphA2)/focal adhesion kinase (FAK)/Paxillin signaling pathways. In this study, we further investigated the anti-VM activity of norcantharidin (NCTD) as a VM inhibitor for gallbladder cancers and the underlying mechanisms. In vivo and in vitro experiments to determine the effects of NCTD on tumor growth, host survival, VM formation of GBC-SD nude mouse xenografts, and vasculogenic-like networks, malignant phenotypes i.e., proliferation, apoptosis, invasion and migration of GBC-SD cells. Expression of VM signaling-related markers EphA2, FAK and Paxillin in vivo and in vitro were examined by immunofluorescence, western blotting and real-time polymerase chain reaction (RT-PCR), respectively. The results showed that after treatment with NCTD, GBC-SD cells were unable to form VM structures when injecting into nude mouse, growth of the xenograft was inhibited and these observations were confirmed by facts that VM formation by three-dimensional (3-D) matrix, proliferation, apoptosis, invasion, migration of GBC-SD cells were affected; and survival time of the xenograft mice was prolonged. Furthermore, expression of EphA2, FAK and Paxillin proteins/mRNAs of the xenografts was downregulated. Thus, we concluded that NCTD has potential anti-VM activity against human gallbladder cancers; one of the underlying mechanisms may be via blocking the EphA2/FAK/Paxillin signaling pathway.

Norcantharidin inhibits tumor growth and vasculogenic mimicry of human gallbladder carcinomas by suppression of the PI3-K/MMPs/Ln-5γ2 signaling pathway.

BACKGROUND: Vasculogenic mimicry (VM) is a novel tumor blood supply in some highly aggressive malignant tumors. Recently, we reported VM existed in gallbladder carcinomas (GBCs) and the formation of the special passage through the activation of the PI3K/MMPs/Ln-5γ2 signaling pathway. GBC is a highly aggressive malignant tumor with disappointing treatments and a poor prognosis. Norcantharidin (NCTD) has shown to have multiple antitumor activities against GBCs, etc; however the exact mechanism is not thoroughly elucidated. In this study, we firstly investigated the anti-VM activity of NCTD as a VM inhibitor for GBCs and its underlying mechanisms. METHODS: In vitro and in vivo experiments to determine the effects of NCTD on proliferation, invasion, migration, VM formation, hemodynamic and tumor growth of GBC-SD cells and xenografts were respectively done by proliferation, invasion, migration assays, H&E staining and CD31-PAS double stainings, optic/electron microscopy, tumor assay, and dynamic micro-MRA. Further, immunohistochemistry, immunofluorescence, Western blotting and RT-PCR were respectively used to examine expression of VM signaling-related markers PI3-K, MMP-2, MT1-MMP and Ln-5γ2 in GBC-SD cells and xenografts in vitro and in vivo. RESULTS: After treatment with NCTD, proliferation, invasion, migration of GBC-SD cells were inhibited; GBC-SD cells and xenografts were unable to form VM-like structures; tumor center-VM region of the xenografts exhibited a decreased signal in intensity; then cell or xenograft growth was inhibited. Whereas all of untreated GBC-SD cells and xenografts formed VM-like structures with the same conditions; the xenograft center-VM region exhibited a gradually increased signal; and facilitated cell or xenograft growth. Furthermore, expression of MMP-2 and MT1-MMP products from sections/supernates of 3-D matrices and the xenografts, and expression of PI3-K, MMP-2, MM1-MMP and Ln-5γ2 proteins/mRNAs of the xenografts were all decreased in NCTD or TIMP-2 group; (all P < 0.01, vs. control group); NCTD down-regulated expression of these VM signaling-related markers in vitro and in vivo. CONCLUSIONS: NCTD inhibited tumor growth and VM of human GBCs in vitro and in vivo by suppression of the PI3-K/MMPs/Ln-5γ2 signaling pathway. It is firstly concluded that NCTD may be a potential anti-VM agent for human GBCs.

Contribution of the PI3K/MMPs/Ln-5γ2 and EphA2/FAK/Paxillin signaling pathways to tumor growth and vasculogenic mimicry of gallbladder carcinomas.

Vasculogenic mimicry (VM) is a new tumor blood supply in some highly aggressive malignant tumors. We previously reported VM in human gallbladder carcinomas, 3-D matrices in vitro and nude mouse xenografts in vivo of highly aggressive GBC-SD cells and its clinical significance. In this study, we further studied the underlying mechanisms of VM in gallbladder carcinomas via the 3-D matrix in vitro, the nude mouse xenografts in vivo of GBC-SD or SGC-996 cells, immunohistochemistry (H&E staining and CD31-PAS double staining), electron microscopy, expression of MMP-2, MT1-MMP, PI3K, Ln-5γ2, EphA2, FAK and Paxillin-P proteins/mRNAs determined by SABC, ELISA, immunofluorescence, western blotting and qRT-PCR, respectively. It was shown that all of untreated highly aggressive GBC-SD cells and xenografts formed vasculogenic-like structures within 2 weeks of seeding and injecting, and facilitated the growth of tumor cells or xenografts; whereas poorly aggressive SGC-996 cells or GBC-SD cells treated by TIMP-2 were unable to form the vasculogenic-like structures with the same conditions; and tumor xenograft growth was inhibited. Expression of MMP-2, MT1-MMP proteins/mRNAs from sections and supernates of 3-D matrix in vitro, expression of PI3K, MMP-2, MT1-MMP, Ln-5γ2, EphA2, FAK and Paxillin-P proteins/mRNAs from sections of xenografts in vivo in untreated GBC-SD group was upregulated significantly (all P<0.001); however, expression of these VM signal-related proteins/mRNAs in the SGC-996 group and GBC-SD treated by the TIMP-2 group was significantly downregulated (all P<0.001). Thus, we identified for the first time that highly aggressive GBC-SD cells formed VM in vitro and in vivo through the upregulation of PI3K/MMPs/Ln-5γ2 and/or EphA2/FAK/Paxillin signaling. PI3K/MMPs/Ln-5γ2 and EphA2/FAK/Paxillin as key signaling pathways in a coordinated manner contributed to tumor growth and VM of gallbladder carcinomas and provided novel targets that could be potentially exploited for therapeutic intervention of human gallbladder carcinomas.

[Vasculogenic mimicry in human primary gallbladder carcinoma and clinical significance thereof].

OBJECTIVE: To investigate if there is vasculogenic mimicry (VM) in human primary gallbladder carcinoma and clinical significance thereof. METHODS: Seventy-four specimens of primary gallbladder carcinoma obtained from operation underwent HE staining and double staining of CD(31) and PAS to observe the existence of VM. The correlation of pathological examination and clinical outcomes was analyzed. RESULTS: VM was seen in 10 of the 74 (13.5%) specimens. VM was not correlated with age, sex, location, diameter, differentiation degree, Nevin stage, and invasion depth of tumor, and existence of lymph node metastasis; but was associated with histological type (chi(2) = 10.241, P = 0.017), hepatic metastasis (chi(2) = 11.904, P = 0.01), and poor overall survival (chi(2) = 5.771, P = 0.016). Cox analysis showed that existence of VM, invasion depth, lymph node metastasis, hepatic metastasis, and operational method were independent risk factors of the prognosis of primary gallbladder carcinoma. CONCLUSION: VM exists in human primary gallbladder carcinoma. Those cases of human primary gallbladder carcinoma with VM have a poorer prognosis.