A Novel Alkannin Derivative Suppresses Breast Cancer Proliferation And Angiogenesis Through Modulation Of Stat3 Signaling

Background: Angiogenesis is a cancer hallmark essential for establishment of tumor and metastasis. The elevated expression of the vascular endothelial growth factor (VEGF) in breast cancer is directly regulated by activated STAT-3 protein, and thus it represents a common molecular target for blocking angiogenesis induced by multiple signaling pathways in breast cancer. Therefore STAT3 inhibition is perceived as a promising anti-angiogenic therapy. The natural naphthoquinone compounds like shikonin/alkannin exhibit potent anticancer activities. However, poor solubility, low bioavailability, and unfavorable toxicity profiles limit their clinical efficacy and underscore the need for synthetic napthoquinone derivative-based therapeutic strategies. In the present back drop, we have analysed the anti-angiogenic effects of a novel alkannin derivative, 1-(5,8-dihydroxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-4-methylpent-3-en-1-yl 3-(pyridine-2-yl)propanoate (ALKP), and explored its mechanism of action in breast cancer cells. Methods: We studied the effects of the alkannin derivative in vitro and in vivo. The effects of ALKP were evaluated in vitro using HUVEC and breast cancer cells (MDA-MB231, MDA-MB468) to assess proliferation, invasion, migration, and tube formation. Immunoblotting and gelatin zymography were done to measure the MMP activity, protein expression, and phosphorylation of signaling kinases. Fluorescent microscopy was used to study subcellular localization of proteins. The in vivo effects were analysed by using the matrigel plug assay and 4T1 induced syngeneic mice breast cancer model. Results: ALKP significantly inhibited proliferation, invasion, migration, MMP activity, and tube formation in MDA-MB231 as compared to the parent compound. A significant attenuation in microvessel sprouting from ex vivo rat aortic ring cultures was observed in ALKP-treated rings compared with alkannin. Our mechanistic studies revealed that ALKP inhibited phosphorylation of STAT3, Src, and FAK in MDAMB-231cells. ALKP exhibited potent inhibition of VEGF expression and nuclear localization of phospho-STAT3 in comparison to alkannin. A significant inhibition of in vivo angiogenesis in matrigel plug assay, tumor growth, and lung metastasis in 4T1-induced breast cancer model was shown by ALKP compared with alkannin, with lower toxicity in terms of body weight and other parameters. Immunohistochemical analysis of tumor and matrigel revealed marked decrease in PCNA, CD31, and VEGF-A markers. Conclusion: Collectively our findings demonstrate that ALKP inhibits tumor angiogenesis through inhibiting STAT3 and VEGF signaling. Citation Format: Akanchha Shukla, Ravi Thakur, Sukanya Pandeti, Sabbu Sathish Reddy, Narender Tadigoppula, Durga Prasad Mishra. A novel alkannin derivative suppresses breast cancer proliferation and angiogenesis through modulation of STAT3 signaling [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B124.