TRPV4 channel activation selectively inhibits tumor endothelial cell proliferation

Abstract

Endothelial cell proliferation is a critical event during angiogenesis, regulated by both soluble factors and mechanical forces. Although the proliferation of tumor cells is studied extensively, little is known about the proliferation of tumor endothelial cells (TEC) and its contribution to tumor angiogenesis. We have recently shown that reduced expression of the mechanosensitive ion channel TRPV4 in TEC causes aberrant mechanosensitivity that result in abnormal angiogenesis. Here, we show that TEC display increased proliferation compared to normal endothelial cells (NEC). Further, we found that TEC exhibit high basal ERK1/2 phosphorylation and increased expression of proliferative genes important in the G1/S phase of the cell cycle. Importantly, pharmacological activation of TRPV4, with a small molecular activator GSK1016790A (GSK), significantly inhibited TEC proliferation, but had no effect on the proliferation of NEC or the tumor cells (epithelial) themselves. This reduction in TEC proliferation by TRPV4 activation was correlated with a decrease in high basal ERK1/2 phosphorylation. Finally, using a syngeneic tumor model revealed that TRPV4 activation, with GSK, significantly reduced endothelial cell proliferation in vivo. Our findings suggest that TRPV4 channels regulate tumor angiogenesis by selectively inhibiting tumor endothelial cell proliferation.

TRP channels in brown and white adipogenesis from human progenitors: new therapeutic targets and the caveats associated with the common antibiotic, streptomycin

“…We analyzed the expression pattern of all human TRP channels during in vitro adipogenesis and found strong constitutive expression of TRPs P2, M7, V1, V2, V4, C1, C4, and ML1 in both MSCs and SVF cells, regardless of differentiation status, reflecting their generalized role in cell growth (proliferation and metabolism) and survival (37). Previous studies have ascribed proliferative roles to TRPs C1 (19, 38), C4 (39), V1 (40), V2 (41), V4 (42), and P2 (43). Conversely, the expression of TRPM7 and TRPML1 correlated with cell cycle withdrawal (44, 45).…”

Novel noncanonical regulation of soluble VEGF/VEGFR2 signaling by mechanosensitive ion channel TRPV4

“…Human microvascular endothelial cells (HMECs-1) were obtained from ATCC (Manassas, VA, USA). HUVECs, normal endothelial cells (NECs), and TRPV4 knockout (KO) ECs were cultured as previously described (13,17,19).…”

Endothelial Transient Receptor Potential Channels and Vascular Remodeling: Extracellular Ca2 + Entry for Angiogenesis, Arteriogenesis and Vasculogenesis

“…Moreover, the daily intraperitoneal delivery of GSK improved pericyte coverage in TRPV4 KO mice xenografted with LLC cells and favored cisplatin-induced tumor shrinkage (Adapala et al, 2016). In addition, GSK-induced TRPV4-mediated extracellular Ca 2+ influx inhibited the ERK 1/2 pathway, thereby decreasing A-TEC proliferation in vitro and reducing LLC growth in vivo (Thoppil et al, 2015). These findings, therefore, suggest that, depending on the tumor type, TRPV4 may be inhibited or activated to interfere with malignant vascularization.…”

“…A subsequent report disclosed that TRPV4 down-regulation caused a significant reduction in VE-cadherin expression at cell-to-cell contacts, which further contributed to increase vascular leakage (Cappelli et al, 2019). Overexpression or pharmacological stimulation of TRPV4 with GSK were, however, sufficient to normalize aberrant capillary-like tubules in vitro by restoring their mechanosensitivity toward ECM stiffness through the blockade of basal Rho activity (Thoppil et al, 2015;Adapala et al, 2016). Moreover, the daily intraperitoneal delivery of GSK improved pericyte coverage in TRPV4 KO mice xenografted with LLC cells and favored cisplatin-induced tumor shrinkage (Adapala et al, 2016).…”