Carnosine exerts antitumor activity against bladder cancers in vitro and in vivo via suppression of angiogenesis

Abstract Carnosine, a naturally occurring dipeptide, was recently reported to exhibit anticancer activity; however, the molecular mechanisms and regulators underlying its activity against tumour-associated angiogenesis remain unidentified. In this study, we evaluated the in vitro and in vivo antitumor effects of carnosine in EJ bladder cancer cells and EJ-xenografted BALB/c nude mice, respectively. In addition, in vitro capillary tube formation of HUVECs, ex vivo aortic ring, and in vivo Matrigel plug assays were employed to examine the anti-angiogenic potential of carnosine. Carnosine significantly inhibited EJ cell proliferation. Flow cytometric and immunoblot analyses indicated that carnosine modulated regulators of the G1 cell cycle phase, including cyclin D1, CDK4, and p21WAF1. The mitogen-activated protein kinases, ERK and p38, but not JNK or AKT, responded to carnosine. Carnosine inhibited the migratory and invasive potential of EJ cells by inhibiting MMP-9 activity, which was associated with suppression of binding activity of NF-κB, SP-1, and AP-1. In xenograft tumours, carnosine exhibited antitumor activity equivalent to cisplatin, but no weight loss occurred in carnosine-treated mice. In HUVECs, carnosine inhibited VEGF-mediated proliferation, colony tube formation, migration, and invasion. The anti-angiogenic activity of carnosine was partially due to the suppression of VEGFR-2-mediated ERK/AKT/eNOS signalling and MMP-2. Furthermore, using aortic ring and Matrigel plug assays, we confirmed the anti-angiogenic activity of carnosine. Given that targeting tumour-associated angiogenesis is a proved effective therapeutic strategy, our results may provide valuable information for the development of preventive or therapeutic agents for bladder cancer patients.