Effects of RhoC downregulation on the angiogenesis characteristics of myeloma vascular endothelial cells

Background: Tumor angiogenesis plays an important role in disease progression, and RhoC has been previously found to be expressed in vascular endothelial cells (VECs); however, its role in tumor angiogenesis requires clarification. This study aimed to explore the effects of RhoC downregulation on the cytoskeleton, pseudopod formation, migration ability, and canalization capacity of myeloma vascular endothelial cells (MVECs) in vitro.

Materials and methods: The expression of RhoC in MVECs and human umbilical vein endothelial cells (HUVECs) was knocked down by shRNA, and the expression levels of RhoC mRNA were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The cytoskeletal changes and pseudopods were observed by laser scanning confocal and scanning electron microscopy; VECs were incubated in two-dimensional Matrigel and three-dimensional microcarriers to observe tube-like structures and budding status, respectively. The protein expression of RhoC, phosphorylation of mitogen-activated protein kinase (p-MAPK), and Rho-associated coiled-coil kinase (ROCK) was determined by Western blotting. The expression of RhoC in VECs was downregulated by RhoC shRNA, thereby decreasing the number of pseudopods, two-dimensional tube-like structures, and buds.

Results: When RhoC was downregulated, the expression levels of ROCK and phosphorylation of MAPK were both decreased (P < 0.05). Moreover, the expression levels of RhoC and phosphorylation of MAPK and three-dimensional budding numbers were higher in MVECs than in HUVECs (P < 0.05). The downregulation of RhoC expression in MVECs and HUVECs inhibited pseudopod formation, migration, canalization ability, and angiogenesis (P < 0.05).

Conclusion: Our data indicated that MVECs and HUVECs were well suited for angiogenesis research, but the former cell type was shown to be more advantageous in terms of budding numbers. RhoC plays a pivotal role in MVECs angiogenesis, and the downregulation of RhoC expression could inhibit angiogenesis via the RhoC/MAPK and RhoC/ROCK signaling pathways.