A new series of phenylaminopyrimidine (PAP) derivatives was designed and synthesized to act against tyrosine kinases for the treatment of cancer.

Targeting tyrosine kinases is attracting considerable attention for cancer therapeutics, nonetheless colorectal cancer. Herein we rationally designed and synthesized a group of 4-(3-methoxy-5-methylphenyl)-5-(pyridine-4-yl)pyrimidine-2-amine derivatives as potential inhibitors for tyrosine kinase. Synthesized compounds share a general structure and vary in substituents at position-2 of the terminal pyridine ring. The hydroxy-analogue of each methoxy derivative was also prepared to evaluate the effect of the methoxy group, at the phenyl ring in position-4 of the pyrimidine moiety, on activity. Compounds 1 (2-chloropyridyl and methoxyphenyl), 2 (2-chloropyridyl and hydroxyphenyl), 3 (2-(pyridine-3-yl)pyridyl and methoxyphenyl), 4 (2-(pyridine-3-yl)pyridyl and hydroxyphenyl), 5 (2-phenylpyridyl and hydroxyphenyl), 6 (2-(4-cyanophenyl)pyridyl and hydroxyphenyl) and 7 (2-(4-acetylphenyl)pyridyl and hydroxyphenyl) showed 29% to 79% tyrosine kinase inhibitory activity. Yet, cytotoxicity of all compounds were assessed against colorectal cancer cells (HT29 and HCT116) using SRB assay. Any compound (at 10 μM concentration) induced considerable viability drop was further assessed using detailed dose response curve and its cytotoxic parameters were calculated. Compounds 8 (2-(4-(N,N-dimethylamino)phenyl)pyridyl and hydroxyphenyl), 5, 6 and 7 showed considerable cytotoxic activities against HCT116 cells with IC50's of 9.18, 10.37, 9.47 and 16.60 μM, respectively. In addition, compounds 9 (2-chloropyridyl, methoxyphenyl and free 2-amino), 2, 3, 4, 5 and 6 showed considerable cytotoxicity against HT29 cells with IC50's of 9.31, 7.48, 11.26, 6.37, 9.89 and 7.14 μM, respectively. The mechanisms of cell killing effect of compounds with considerable anti-proliferative/cytotoxic activity were further assessed using cell cycle analysis (DNA content flowcytometry) and Annexin-V/FITC apoptosis assessment. Compound 2 induced antiproliferative effect which might be attributed to induction of cell cycle arrest at the G0/G1 phase; cell population in G0/G1 phase after treatment with compound 2 was 59.7±0.7% compared to 53.4±1.6% for control untreated cells. Compounds 4, 5, 6 and 7 induced significant cell cycle arrest at G2/M phase with cell populations equals 25.1±0.6%, 24.8±0.4%, 24.0±0.7% and 25.9±0.1%, respectively, compared to 19.3±1.6% for control untreated cells. Cell cycle arrest induced by compounds 1, 2, 3, 4, 6 and 7 resulted in significant apoptosis in colorectal cancer cells. In conclusion, this group of tyrosine kinase inhibitors showed promising anti-proliferative/cytotoxic effects in colorectal cancer cell lines attributed to cell cycle arrest. Further studies for the different cell cycle check point proteins and kinases are undergoing to clarify the exact underlying mechanism of cell killing attributed to each one of these compounds. Citation Format: Hanan A. Assiri, Hawazen A. BinMahfouz, Fahad A. Alabbasi, Marc Devocelle, Ibrahim M. El-deeb, Ahmed M. Al-Abd. Design and synthesis of novel tyrosine kinase enzyme inhibitors and evaluating their anti-colorectal cancer activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1675.