Targeting HIF-1α and VEGF by lentivirus-mediated RNA interference reduces liver tumor cells migration and invasion under hypoxic conditions

Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is a key transcription factor to initiate the expressions of distinct pro-angiogenic growth genes, particularly the expression of vascular endothelial growth factor (VEGF). CoCl2 was used in rat liver tumor cell line McA RH-7777 to stimulate hypoxia to mimic the hypoxic conditions induced by transcatheter arterial chemoembolization (TACE). CCK8 assays were performed to examine the effect of hypoxia on cell viability. Real-time qRT-PCR, western blot and ELISA assays were used to measure the expression of HIF-1 alpha and VEGF in McA RH-7777 cells under hypoxic conditions, respectively. Lentivirus-mediated HIF-1 alpha and/or VEGF-specific shRNA was used to establish single or HIF-1 alpha and VEGF double knocking-down McA RH-7777 cells. Transwell assays were performed to examine the effect of HIF-1 alpha and VEGF knocking-down on McA RH-7777 cells migration and invasion. The mRNA and protein expression level of HIF-1 alpha and VEGF were remarkably up-regulated in McA RH-7777 cells under hypoxic conditions, respectively. The knockdown of HIF-1 alpha or VEGF significantly reduced the expression of the secreted VEGF. More importantly, knockdown of both HIF-1 alpha and VEGF resulted in the best effective inhibitory effect in VEGF expression, and in turn remarkably reduced the cell migration and invasion activity. Our findings showed that HIF-1 alpha play an important role in the stimulation of the secreted VEGF expression under hypoxic conditions, suggesting that targeting both HIF-1 alpha and VEGF could represent a potential therapeutic strategy in combination with TACE in the treatment of liver tumors.