Novel antiproliferative agents bearing substituted thieno[2,3-d]pyrimidine scaffold as dual VEGFR-2 and BRAF kinases inhibitors and apoptosis inducers; design, synthesis and molecular docking

A series of novel thieno[2,3-d]pyrimidine derivatives was designed and synthesized based on multitarget directed drug design strategy. All the newly synthesized compounds were evaluated for their antiproliferative activity in the National Cancer Institute (NCI) against a panel of 60 tumor cell lines. Compounds 4a and 4b showed a significant antiproliferative activity at 10 µM dose, and were accordingly evaluated at five dose concentrations. They showed potent and broad-spectrum antiproliferative activity, with GI₅₀ values in the micromolar range of 1.44-6.93 µM and 1.66-5.82 µM, respectively. They also showed TGI values in the cytostatic range of 3.49-97.3 µM and 3.33-77.3 µM respectively. These two compounds potently inhibited VEGFR-2 with IC₅₀ = 0.111 ± 0.006 and 0.049 ± 0.003 µM, BRaf^V600E with IC₅₀ = 0.089 ± 0.005 and 0.063 ± 0.003 µM and BRaf^WT IC₅₀ = 0.071 ± 0.004 and 0.05 ± 0.003 µM, respectively in comparison to sorafenib IC₅₀ values of 0.031 ± 0.002, 0.035 ± 0.002 and 0.021 ± 0.001 µM against VEGFR-2, BRaf^V600E and BRaf^WT, respectively. Compounds 4a and 4b showed also potent down-regulation of total VEGFR-2 and phosphorylated VEGFR-2. In addition, the HUVECs migratory potential was greatly reduced resulting in significantly disrupted wound healing patterns after treatment with compounds 4a and 4b for 72 h. Furthermore, Compounds 4a and 4b induced Apoptosis by 22.82- and 25.81-fold increase in the total Apoptosis percentage in breast Cancer MCF7 cell line. This apoptotic activity was supported by an increase in the level of apoptotic caspase-9 by 6.17- and 9.07-fold, respectively. Moreover, the cell cycle analysis showed that compounds 4a and 4b arrested the cell cycle mainly in the G1 and G1/S phases, respectively. The molecular modeling studies were performed to assess the binding pattern and affinity of derivatives 4a and 4b toward the VEGFR-2 and BRaf active sites.