BACKGROUNDBoron, a trace element, is involved in various physiological and metabolic processes, and recent studies suggest that boron compounds may have potential in cancer prevention and treatment. In this study, the antiangiogenic effects of a boron compound, borax pentahydrate (BPH), were investigated. Angiogenesis is a tightly regulated biological process responsible for the formation of new blood vessels from existing vasculatures. This process plays a critical role in cancer progression, making it an important target for cancer therapy. Pancreatic and kidney cancers are difficult to treat because they are aggressive and resistant to chemotherapy.METHODSThe antiproliferative activity was evaluated using the MTT assay, while antiangiogenic effects were tested through in vitro tube formation assays and in ovo chick chorioallantoic membrane (CAM) assay. The effect of BPH on VEGF levels was determined using Western blot analysis in HUVEC, ACHN, PANC-1 cells. The effect of BPH on tumor angiogenesis was investigated with an in vivo Ehrlich ascites carcinoma model (EAC).RESULTSBPH exhibited potent antiproliferative and antiangiogenic activities, inhibiting the proliferation of ACHN, PANC-1, and HUVECs, disrupting endothelial tube formation, and inhibiting vascular formation on the CAM surface in a dose-dependent manner. VEGF levels were significantly decreased in ACHN, PANC-1 and HUVECs. There was also a decrease in VEGF and TGF-β1 levels in BPH-treated tumor groups. In addition, BPH caused a decrease in tumor size.CONCLUSIONThese findings suggest that BPH may be a new antiangiogenic and antitumoral agent. BPH may contribute to drug development studies targeting angiogenesis-related diseases as a promising new therapeutic agent.