Sprouty1, a new target of the angiostatic agent 16K prolactin, negatively regulates angiogenesis

Abstract

BackgroundDisorganized angiogenesis is associated with several pathologies, including cancer. The identification of new genes that control tumor neovascularization can provide novel insights for future anti-cancer therapies. Sprouty1 (SPRY1), an inhibitor of the MAPK pathway, might be one of these new genes. We identified SPRY1 by comparing the transcriptomes of untreated endothelial cells with those of endothelial cells treated by the angiostatic agent 16 K prolactin (16 K hPRL). In the present study, we aimed to explore the potential function of SPRY1 in angiogenesis.ResultsWe confirmed 16 K hPRL induced up-regulation of SPRY1 in primary endothelial cells. In addition, we demonstrated the positive SPRY1 regulation in a chimeric mouse model of human colon carcinoma in which 16 K hPRL treatment was shown to delay tumor growth. Expression profiling by qRT-PCR with species-specific primers revealed that induction of SPRY1 expression by 16 K hPRL occurs only in the (murine) endothelial compartment and not in the (human) tumor compartment. The regulation of SPRY1 expression was NF-κB dependent. Partial SPRY1 knockdown by RNA interference protected endothelial cells from apoptosis as well as increased endothelial cell proliferation, migration, capillary network formation, and adhesion to extracellular matrix proteins. SPRY1 knockdown was also shown to affect the expression of cyclinD1 and p21 both involved in cell-cycle regulation. These findings are discussed in relation to the role of SPRY1 as an inhibitor of ERK/MAPK signaling and to a possible explanation of its effect on cell proliferation.ConclusionsTaken together, these results suggest that SPRY1 is an endogenous angiogenesis inhibitor.

MicroRNA-29c Is a Signature MicroRNA under High Glucose Conditions That Targets Sprouty Homolog 1, and Its in Vivo Knockdown Prevents Progression of Diabetic Nephropathy

“…It is also important to emphasize that several recent studies have implicated the potential role of miRNAs and Spry1 as regulators of extracellular matrix proteins. For instance, miR-377 was shown to play a pivotal role in increased fibronectin protein production in mesangial cells (8), and a recent report by Sabatel et al (70) provided evidence that Spry1 may serve as an endogenous angiogenesis inhibitor, whose silencing can modulate the interaction between cells and extracellular matrix proteins. Interestingly, although the role of Spry1 on fibronectin synthesis has recently been described (70), the effect of Spry1 on cell apoptosis is less understood with a number of published studies suggesting that Spry1 can increase or decrease apoptosis at the cellular level, depending on the cellular context (12,67,71,72).…”

In non‐small cell lung cancer mitogenic signaling leaves Sprouty1 protein levels unaffected

“…A similar observation is already documented in response to 16 K prolactin, where a strong increase at RNA level is hardly pronounced at the protein level. 22 Although mitogen-induced signaling as well as expression of oncogenic Ras isoforms had no influence on Spry1 levels in serumstarved cells, tumor cells harboring a mutated version of K-Ras express on average more Spry1 protein. In agreement with our observation, it was shown that in tumorderived cells, increased Spry1 expressions are accompanied by higher levels of phosphorylated ERK1 and 2 (pERK1/2).…”

MiR-205 is downregulated in hereditary hemorrhagic telangiectasia and impairs TGF-beta signaling pathways in endothelial cells

“…After transfection for 24 h, cells were washed and kept for additional 48 h in serum-free medium. Functional assays were performed as previously described below and in [34,35].…”