Overexpression of HIF-1α in primary gallbladder carcinoma and its relation to vasculogenic mimicry and unfavourable prognosis

As a novel mode of tumor neovascularization, vasculogenic mimicry (VM) has been reported to increase tumor-related mortality in many different solid tumors. In the present study, two established human gallbladder carcinoma (GBC) cell lines (highly aggressive GBC-SD and poorly aggressive SGC-996) cultured on a three-dimensional matrix were assessed for the ability of VM channel formation under normoxic or hypoxic conditions. In addition, the relationship between HIF-1 alpha gene expression and VM channel formation of GBC cells in vitro was measured using the small interfering RNA (siRNA) technique, western blotting and real-time reverse transcription (RT)-PCR analysis. Furthermore, H&E and CD31/periodic acid-Schiff (PAS) staining were used to observe VM in GBC tissue samples. Additionally, all seventy-one specimens with VM and non-VM were stained for hypoxia inducible factor-1 alpha (HIF-1 alpha) and its correlation with clinicopathological features and prognosis was analyzed simultaneously. We found that hypoxia could induce more VM channel formation and elevated HIF-1 alpha expression in highly aggressive GBC-SD cells. HIF-1 alpha siRNA efficiently knocked down HIF-1 alpha expression and GBC VM networks under either normoxic or hypoxic conditions. VM was present in human primary GBC and overexpression of HIF-1 alpha was significantly correlated with depth of invasion and perineural involvement in the non-VM group. Moreover, VM and HIF-1 alpha were independent factors for the overall survival of GBC patients and correlated with decreased survival. In conclusion, VM was present in human GBC. As a critical mediator in VM formation, high expression of HIF-1 alpha was associated with VM and tumor progression in GBC patients.