Histone Deacetylase 7 Silencing Alters Endothelial Cell Migration, a Key Step in Angiogenesis

Abstract

Abstract-Global inhibition of class I and II histone deacetylases (HDACs) impairs angiogenesis. Herein, we have undertaken the identification of the specific HDAC(s) with activity that is necessary for the development of blood vessels. Using small interfering RNAs, we observed that HDAC7 silencing in endothelial cells altered their morphology, their migration, and their capacity to form capillary tube-like structures in vitro but did not affect cell adhesion, proliferation, or apoptosis. Among several factors known to be involved in angiogenesis, platelet-derived growth factor-B (PDGF-B) and its receptor (PDGFR-␤) were the most upregulated genes following HDAC7 silencing. We demonstrated that their increased expression induced by HDAC7 silencing was partially responsible for the inhibition of endothelial cell migration. In addition, we have also shown that treatment of endothelial cells with phorbol 12-myristate 13-acetate resulted in the exportation of HDAC7 out of the nucleus through a protein kinase C/protein kinase D activation pathway and induced, similarly to HDAC7 silencing, an increase in PDGF-B expression, as well as a partial inhibition of endothelial cell migration. Collectively, these data identified HDAC7 as a key modulator of endothelial cell migration and hence angiogenesis, at least in part, by regulating PDGF-B/PDGFR-␤ gene expression. Because angiogenesis is required for tumor progression, HDAC7 may represent a rational target for therapeutic intervention against cancer. A ngiogenesis is a crucial biologic event in physiologic conditions but also in many pathologic situations such as inflammation, tumor growth, and metastasis. This process depends on the activation/inactivation of genes associated with proliferation, adhesion, migration, and invasion of endothelial cells. 1,2 Histone deacetylases (HDACs) constitute a family of enzymes that regulate gene transcription by modifying the acetylation level of histones and nonhistone proteins. 3,4 Global inhibition of HDAC activity inhibits angiogenesis and tumor growth both in vitro and in vivo both by reducing expression of proangiogenic factors and enhancing expression of angiogenic inhibitors. 5-10 At the time our study was initiated, no information was available regarding the identity of the HDAC(s) that could intervene in the control of angiogenesis. However, while we were preparing this report, a study was published that indicates a role for HDAC7 in the maintenance of vascular integrity. 11 Here, we have applied a gene-silencing strategy using small interfering (si)RNAs efficiently targeting HDAC1 through HDAC7 in endothelial cells stimulated to form capillary-like structures. Our results indicate that HDAC7 is necessary for the assembly of endothelial cell in tube-like structures in vitro. We further show HDAC7 silencing causes cell shape changes and decreases endothelial cell migration, at least in part, through an upregulation of platelet-derived growth factor (PDGF)-B and its ␤ receptor (PDGFR-␤). Moreover, phorbol 12-myristate 13-acetate...

Control of endothelial cell proliferation and migration by VEGF signaling to histone deacetylase 7

“…These findings indicate that HDAC7 acts as a molecular switch to dynamically regulate VEGF signaling. The ability of HDAC7 to mediate VEGF signaling is consistent with recent studies showing that HDAC7 is critical for angiogenesis (19,20), a process in which VEGF plays a key role. We also found that other peptide growth factors, which complement or coordinate the actions of VEGF in regulating endothelial functions, also induce HDAC7 phosphorylation, albeit to a reduced level relative to VEGF.…”

“…HDAC5 and -9 function as stressresponsive inhibitors of cardiac growth (16,17), HDAC4 represses chondrocyte growth and differentiation (18), and HDAC7 maintains vascular integrity by repressing matrix metalloprotease 10 (MMP10) expression in ECs (19). A role for HDAC7 in modulating angiogenesis has also been suggested from in vitro assays (19,20). However, whether VEGF acts through HDAC7 to control angiogenesis and endothelial functions is unknown.…”

HDAC4 represses p21WAF1/Cip1 expression in human cancer cells through a Sp1-dependent, p53-independent mechanism

“…The identification of cancer-related isoforms of HDAC has therapeutic interest in oncology as it might lead to the development of more specific and more efficient HDAC inhibitors with less toxicity and less side effects for patients. Using a small interfering RNA (siRNA) strategy, we have recently observed that specific silencing of HDAC7 led to a similar inhibition of angiogenesis to that observed with non-selective HDAC inhibitors suggesting that HDAC7 is probably the most relevant target(s) for inhibiting angiogenesis, one of the crucial step in cancer development (Mottet et al, 2007). Here, using a similar approach, we found that silencing of HDAC4 induces expression of p21 WAF1/Cip1 in various human cancer cell lines and decreases cancer cell proliferation in vitro and tumor growth in vivo, arguing perhaps that specific HDAC4 inhibitor could be also directly used as an effective chemotherapeutic molecule in cancer treatment.…”

Histone deacetylase 7, a potential target for the antifibrotic treatment of systemic sclerosis

“…Consistent with this, it has recently been reported that silencing of HDAC-7 also has profound effects on endothelial cells. Mottet et al (17) reported evidence of an altered migration of human umbilical vein endothelial cells (HUVECs) upon silencing of HDAC-7. They showed that this disturbance was at least partly due to an up-regulation of PDGF-B and PDGFR␤.…”

“…Even though it is almost undetectable in healthy skin, studies have revealed the increased presence of PDGF and PDGFRs in biopsy samples of SSc skin (16). According to Mottet et al (17), HDAC-7 silencing up-regulated the expression of PDGF-B and its receptor PDGFR␤ in endothelial cells. In order to examine whether gene knockdown of HDAC-7 alters the expression of PDGF-B and PDGFR␤ in SSc fibroblasts, we analyzed changes in the transcript expression levels of these genes in cells treated with HDAC-7 siRNA (n ϭ 6 each).…”