Knock-Down of CD44 Regulates Endothelial Cell Differentiation via NFκB-Mediated Chemokine Production

Abstract

A striking feature of microvascular endothelial cells is their capacity to fuse and differentiate into tubular structures when grown in three-dimensional (3D) extracellular matrices, in collagen or Matrigel, mimicking the in vivo blood vessel formation. In this study we demonstrate that human telomerase-immortalised foreskin microvascular endothelial (TIME) cells express high levels of the hyaluronan receptor CD44 and the hyaluronidase HYAL2. Knock-down of CD44 or HYAL2 resulted in an inability of TIME cells to form a tubular network, suggesting a key regulatory role of hyaluronan in controlling TIME cell tubulogenesis in 3D matrices. Knock-down of CD44 resulted in an upregulation of mRNA expression of the chemokines CXCL9 and CXCL12, as well as their receptors CXCR3 and CXCR4. This was accompanied by a defect maturation of the tubular structure network and increased phosphorylation of the inhibitor of NFκB kinase (IKK) complex and thus translocation of NFκB into the nucleus and activation of chemokine targed genes. Furthermore, the interaction between CD44 and hyaluronan determines the adhesion of breast cancer cells. In summary, our observations support the notion that the interaction between CD44 and hyaluronan regulates microvascular endothelial cell tubulogenesis by affecting the expression of cytokines and their receptors, as well as breast cancer dissemination.

Activated ERK1/2 increases CD44 in glomerular parietal epithelial cells leading to matrix expansion

“…35, 44, 45 However, in endothelial cells, knocking down CD44 had no effect on ERK1/2. 46 Similarly, in the current studies, CD44 had no effect on ERK1/2 activation. Our results showed a spectrum of staining for both CD44/β-gal and for pERK.…”

Transactivation of the Receptor-tyrosine Kinase Ephrin Receptor A2 Is Required for the Low Molecular Weight Hyaluronan-mediated Angiogenesis That Is implicated in Tumor Progression

“…Wang et al (70) reported that CD44 regulates EC proliferation and tubule formation induced by HA fragments in HUVEC. In telomerase-immortalized foreskin microvascular ECs, Olofsson et al (71) demonstrated that inhibiting CD44 or Hyal2 expression prevented tubular network formation in three-dimensional matrices. In addition, CD44 and TLR4 can be physically associated in a signaling complex after exposure to HA, and endothelial TLR4 regulates certain responses to HA fragments (72,73).…”

Hyaluronan Regulation of Endothelial Barrier Function in Cancer

“…Wang, Cao, et al (2011) reported that CD44 regulates EC proliferation and tubule formation induced by HA fragments in HUVECs. In telomerase-immortalized foreskin microvascular EC, Olofsson, Porsch, and Heldin (2014) demonstrated that inhibiting CD44 or Hyal2 expression prevented tubular network formation in 3D matrices. In addition, CD44 and TLR4 can be physically associated in a signaling complex following exposure to HA and endothelial TLR4 regulates certain responses to HA fragments (Taylor et al, 2004, 2007).…”