Targeting VEGFR-2 in breast cancer: synthesis and in silico and in vitro characterization of quinoxaline-based inhibitors

Abstract

A novel series of quinoxaline derivatives was designed and synthesized to target VEGFR-2, a receptor critical in cancer progression, with a focus on favorable pharmacophoric features. Among these derivatives, compound 11d emerged as a promising candidate, exhibiting potent cytotoxicity against MDA-MB-231 and MCF-7 cancer cell lines, with IC₅₀ values of 21.68 μM and 35.81 μM, respectively, while displaying significantly reduced toxicity in normal cell lines WI-38 and WISH (IC₅₀ values of 82.46 μM and 75.27 μM). Compared to standard treatments doxorubicin and sorafenib, compound 11d demonstrated a favorable therapeutic window. Inhibition assays showed that 11d inhibits VEGFR-2 with an IC₅₀ of 62.26 nM ± 2.77, comparable to sorafenib. Mechanistically, treatment with 11d upregulated pro-apoptotic markers BAX, caspase-8, and caspase-9, while downregulating the anti-apoptotic marker Bcl-2, resulting in a significant BAX/Bcl-2 ratio increase (16.11). A wound healing assay confirmed 11d's anti-migratory effects, limiting wound closure in MDA-MB-231 cells to 27.51% compared to untreated cells. Additionally, flow cytometry revealed that 11d induced both early (46.43%) and late apoptosis (31.49%) in MDA-MB-231 cells, alongside G1 phase cell cycle arrest, reducing S and G2/M phase progression. Molecular docking and dynamics simulations over 200 ns demonstrated stable binding of compound 11d to VEGFR-2, with docking scores superior and comparable to sorafenib. Density Functional Theory (DFT) calculations underscored 11d's stability and reactivity, while in silico ADMET analysis predicted a favorable safety profile over sorafenib, particularly with respect to carcinogenic and chronic toxicity risks. These findings indicate that quinoxaline derivative 11d holds potential as a selective and effective VEGFR-2 inhibitor with promising antitumor and anti-metastatic properties, warranting further investigation.