Novel endogenous angiogenesis inhibitors and their therapeutic potential

ERK activation in endothelial cells is a novel marker during neovasculogenesis

Vasculogenesis is essential during early development to construct networks transporting oxygen, blood and nutrients. Tip and stalk cells are specialized endothelial cells involved in novel vessel formation because of their behavior such as sprouting as a leading cell and following tip cell. However, the spatiotemporal details determining the emergence of these cells are unknown. Here, we first show that the ERK activity in endothelial cells represents the precursor of tip and stalk cells for vasculogenesis in zebrafish. We identified that tip and stalk cells for intersegmental vessel (ISV) formation were already specialized in the dorsal aorta (DA) before sprouting. Furthermore, similar specialization was observed in tip cells during parachordal vessel (PAV) formation in lymphangiogenesis. We also identified that the ERK activity was required for specialized cells to emerge from existing blood vessels. Our data show that the ERK activity is a novel marker for determining the emergence of cells in both angiogenesis and lymphangiogenesis.

IGF1 3'UTR functions as a ceRNA in promoting angiogenesis by sponging miR-29 family in osteosarcoma

Osteosarcoma is one of the most common malignant bone tumors in human worldwide. Angiogenesis is a pivotal process during osteosarcoma development. Insulin-like growth factor 1 (IGF1) has been reported to promote angiogenesis. However, the role of 3' untranslational region (3'UTR) of IGF1 mRNA in angiogenic activity in osteosarcomas is still unknown. In the present study, we performed gain-of-function assays to investigate the role of IGF1-3'UTR in angiogenesis. For the first time, we demonstrated that IGF1 3'UTR increased VEGF expression and promotes angiogenesis in osteosarcoma cells. In addition, RNA-immunoprecipitation and luciferase reporter assays showed that IGF1 3'UTR was a direct target of miR-29s. Our data also demonstrated that there existed a competition of miR-29s between IGF1-3'UTR and VEGF mRNA, and IGF1-3'UTR promoted angiogenesis at least in part via sponging miR-29s. Taken together, our study suggests that IGF1-3'UTR functions as a ceRNA in promoting angiogenesis by sponging miR-29s in osteosarcoma.

DW10075, a novel selective and small-molecule inhibitor of VEGFR, exhibits antitumor activities both in vitro and in vivo

AIM

Targeting the VEGF/VEGF receptor (VEGFR) pathway has proved to be an effective antiangiogenic approach for cancer treatment. Here, we identified 6-((2-((3-acetamidophenyl)amino)pyrimidin-4-yl)oxy)-N-phenyl-1-naphthamide (designated herein as DW10075) as a novel and highly selective inhibitor of VEGFRs.

METHODS

In vitro tyrosine kinase activity was measured using ELISA, and intracellular signaling pathway proteins were detected by Western blot analysis. Endothelial cell proliferation was examined with CCK-8 assays, and tumor cell proliferation was determined with SRB assays. Cell migration, tube formation and rat aortic ring assays were used to detect antiangiogenic activity. Antitumor efficacy was further evaluated in U87-MG human glioblastoma xenograft tumors in nude mice receiving DW10075 (500 mg · kg(-1) · d(-1), po) for two weeks.

RESULTS

Among a panel of 21 kinases tested, DW10075 selectively inhibited VEGFR-1, VEGFR-2 and VEGFR-3 (the IC50 values were 6.4, 0.69 and 5.5 nmol/L, respectively), but did not affect 18 other kinases including FGFR and PDGFR at 10 μmol/L. DW10075 significantly blocked VEGF-induced activation of VEGFR and its downstream signaling transduction in primary human umbilical vein endothelial cells (HUVECs), thus inhibited VEGF-induced HUVEC proliferation. DW10075 (1-100 nmol/L) dose-dependently inhibited VEGF-induced HUVEC migration and tube formation and suppressed angiogenesis in both the rat aortic ring model and the chicken chorioallantoic membrane model. Furthermore, DW10075 exhibited anti-proliferative activity against 22 different human cancer cell lines with IC50 values ranging from 2.2 μmol/L (for U87-MG human glioblastoma cells) to 22.2 μmol/L (for A375 melanoma cells). In U87-MG xenograft tumors in nude mice, oral administration of DW10075 significantly suppressed tumor growth, and reduced the expression of CD31 and Ki67 in the tumor tissues.

CONCLUSION

DW10075 is a potent and highly selective inhibitor of VEGFR that deserves further development.