Design, Synthesis, and Functional Studies on Noscapine and Cotarnine Amino Acid Derivatives as Antitumor Agents.

Noscapine, a phthalide isoquinoline alkaloid isolated from the opium poppy, alongside cotarnine, a tetrahydroisoquinoline (THIQ) scaffold produced by the oxidative degradation of noscapine, has exhibited antitumor activities against several types of cancer. Although derivatization with amino acids is regarded as a promising strategy to improve chemotherapeutics' anticancer properties, amino acid conjugates of noscapine and cotarnine have been the least investigated. In the present study, 20 amino acid conjugated derivatives of noscapine and cotarnine at the 6-position were synthesized and evaluated for anticancer activity in both in vitro and in vivo conditions. Analysis of the antiproliferative activity against 4T1 mammary carcinoma tumor cells showed that compounds 6h (noscapine-phenylalanine), 6i (noscapine-tryptophan), and 10i (cotarnine-tryptophan) with IC50 values of 11.2, 16.3, and 54.5 µM, respectively, were found to be far more potent than noscapine (IC50 = 215.5 µM) and cotarnine (IC50 = 575.3 µM) and were consequently opted for further characterization. Annexin V and propidium iodide staining followed by flow cytometry demonstrated improved apoptotic activity of compounds 6h, 6i, and 10i compared to those of noscapine and cotarnine. In a murine model of 4T1 mammary carcinoma, noscapine-tryptophan inhibited tumor growth more effectively than noscapine and the other amino acid conjugates without adverse effects. Moreover, molecular docking studies conducted on tubulin as the intracellular target of noscapine suggested a good correlation with experimental observations. Based on these results, noscapine-tryptophan could be a promising candidate for further preclinical investigations.

A VEGFB-Based Peptidomimetic Inhibits VEGFR2-Mediated PI3K/Akt/mTOR and PLCγ/ERK Signaling and Elicits Apoptotic, Antiangiogenic, and Antitumor Activities.

Vascular endothelial growth factor receptor 2 (VEGFR2) mediates VEGFA signaling mainly through the PI3K/AKT/mTOR and PLCγ/ERK1/2 pathways. Here we unveil a peptidomimetic (VGB3) based on the interaction between VEGFB and VEGFR1 that unexpectedly binds and neutralizes VEGFR2. Investigation of the cyclic and linear structures of VGB3 (named C-VGB3 and L-VGB3, respectively) using receptor binding and cell proliferation assays, molecular docking, and evaluation of antiangiogenic and antitumor activities in the 4T1 mouse mammary carcinoma tumor (MCT) model showed that loop formation is essential for peptide functionality. C-VGB3 inhibited proliferation and tubulogenesis of human umbilical vein endothelial cells (HUVECs), accounting for the abrogation of VEGFR2, p-VEGFR2 and, subsequently, PI3K/AKT/mTOR and PLCγ/ERK1/2 pathways. In 4T1 MCT cells, C-VGB3 inhibited cell proliferation, VEGFR2 expression and phosphorylation, the PI3K/AKT/mTOR pathway, FAK/Paxillin, and the epithelial-to-mesenchymal transition cascade. The apoptotic effects of C-VGB3 on HUVE and 4T1 MCT cells were inferred from annexin-PI and TUNEL staining and activation of P53, caspase-3, caspase-7, and PARP1, which mechanistically occurred through the intrinsic pathway mediated by Bcl2 family members, cytochrome c, Apaf-1 and caspase-9, and extrinsic pathway via death receptors and caspase-8. These data indicate that binding regions shared by VEGF family members may be important in developing novel pan-VEGFR inhibitors that are highly relevant in the pathogenesis of angiogenesis-related diseases.