Abstract 16966: MicroRNA-92a Differentially Regulates Cell Cycle Proliferation and Angiogenesis in Huvec And Hepg2 Cells
Introduction: The conserved miR17~92 cluster, is up-regulated in tumors, and its OE promotes tumor angiogenesis and growth. Recent studies indicate that miR92a is anti-angiogenic while the regulation of angiogenesis by miR17/20 is context-dependent.
Hypothesis: miR92a action is also context and cell type-dependent and differentially regulates cell growth and angiogenesis in tumor vs endothelial cells.
Methods: HepG2 and HUVECs were transfected with pre and anti miR92a molecules. Cell proliferation was assayed in both cell types using BrdU 48hr after transfection. HUVEC-Matrigel tube formation assays were implemented in parallel to assess angiogenic potential. VEGF was measured in spent media from HepG2 cells and the same media was used in HUVEC tube formation. Protein lysates were collected for WB 48hr after transfections of both cell types.
Results: Pre-miR92a transfection inhibited proliferation of HUVECs while anti-miR92a, but not pre-miR92a inhibited proliferation of HepG2 cells (all, p<0.05). Pre-miR transfection blocked HUVEC tube formation (p<0.01). Tube formation was supported by spent medium from HepG2 cells ± transfection with pre-miR-92a but the ability of HepG2 spent medium to support tube formation was blocked by transfection with anti miR92a (all, p<0.05). Consistent with the latter result, VEGF levels in spent HepG2 media were decreased by transfection with anti-miR92a. In HepG2 cells transfection of anti-miR92a increased PTEN expression and decreased AKT-P-Thr308 (both p<0.05) PTEN and AKT-P-Thr-308 were not affected by miR92a transfection of HUVECs, however pre-miR-92a significantly decreased eNOS, ITG5α, and CCND1 protein levels (all, p<0.05). These results support our hypothesis that miR92a has opposite effect on the angiogenic properties of HepG2 vs HUVECs.
Conclusions: MiR92a augments proliferation of HepG2 cells and promotes angiogenesis by inhibiting PTEN, activating Akt and increasing VEGF expression and secretion. Conversely, miR92a inhibits angiogenesis of HUVECs by targeting angiogenic regulators. The differential contextual functions of miR92a explain why this regulation supports tumor growth and angiogenesis while blocking EC function.
- © 2011 by American Heart Association, Inc.