Design,Synthesis And Biological Evaluation Of Novel CDK2 Inhibitors

The occurrence of malignant tumors is due to abnormal changes and accumulation of genomes,resulted changes in their biological behavior.The combination of various carcinogenic factors led to the malignant tumors.According to the National Bureau of Statistics data in 2015,the incidence of malignant tumors in China accounted for about21.8%of the global incidence of malignant tumors.The reason for the high mortality rate was due to its rapid development and difficulty in eradicating.The cell cycle of malignant tumors had unlimited proliferation characteristics,which was abnormal.Cells proliferate with an orderly cell cycle,CDK2 could bind to the cyclins and directly participate in the process of cell mitosis from G1 to S phase.CDK2 targeted inhibitors?such as Milciclib?Seliciclib and Dinaciclib?had been in clinical phase II/III studies and shown great anti-tumor potential.This paper reviews the targeted therapeutic drugs for tumor molecules,and the advance of CDK2 inhibitors.Considering the CDK2 inhibitor Milciclib as a lead compound,and on the basis of summarizing the structure-activity relationship,I class compounds with5,6-dihydro-1H-pyrimido[4,5-f]quinazoline scaffold and II class compounds with8-cyclopentyl-6-hydroxypteridin-7?8H?-one scaffold were designed and synthesized.All the compounds were not reported in the literatures,and the structures were confirmed by the mass spectrometry and the nuclear magnetic resonance spectroscopy.The targeted compounds of I class were obtained from 1,3-cyclohexanedione?M-1?by condensation,ring formation,oxidation,addition,and hydrolysis reactions or the like.To explore the effection of different substituents on the biological activity when acting on the hinge region and the ribose binding region,we introduced hydrogen,methyl and para-substituted aromatic amines at the2-position and 8-position of the scaffold.Using 5-nitro-2,4-dichloropyrimidine?N-1?as a raw material,compounds of class II were synthesized by substitution,condensation,ring formation,coupling reactions or the like.We introducted hydroxyl group,halogen group,amino group,etc.at the 3-position for generating the hydrogen bond interaction,and the aromatic amines were introduced at the 7-position to maintain the hydrogen bonds of compounds with Leu 83.At the same time,hydrophilic chains which were capable of interacting with the solvent region were introduced in the para position of the aromatic amine.We evaluated the biological activity of target compounds in vitro,including CDK2kinase activity assays and anti-proliferation experiments on breast cancer cell line MCF-7 and colorectal cancer cell line HCT 116.The results of kinase inhibition experiments showed that among the class I compounds,the inhibitory effection of compounds I-10^I-17 was superior to the compounds I-1^I-9 on CDK2 kinase.It indicated that the active group of class I compounds must be the arylamine substituents at the 2-position.The IC₅₀ of the compounds I-20,I-23,I-26,I-27,I-28,I-29,I-31 and I-32 to CDK2 kinase were less than 0.2?M,of which,the IC₅₀ of compounds I-23 and I-28 values 0.11?M and 0.09?M,respectively.This results were similar to the the positive compound Milciclib which IC₅₀ values 0.052?M.The class II compounds with hydroxyl substituents at 3-position and phenylamine substituents at7-position showed potent inhibitory activity on CDK2,and the IC₅₀ values were less than 3?M.While the scaffold with a halogen or amino substituents at 3-position?compound II-9^II-11?showed weak inhibitory activity against CDK2,IC₅₀ values were more than 30?M.The 3-position of the molecular was substituted by a hydroxyl group,and the inhibitory activity was enhanced when hydrophilic groups such as piperazine which were introduced at the para position of the phenylamine at 7-position.The results of anti-proliferation experiments showed that the class I compounds I-20^I-32 and the class II compounds II-4^II-9 had different degrees of anti-proliferative activity on both tumor cells.Compared with the anti-proliferative activity of Milciclib(IC₅₀=1.7?M,1.1?M),compounds I-23(IC₅₀=1.3?M,0.9?M),I-28(IC₅₀=1.1?M,1.4?M),I-31(IC₅₀=1.9?M,1.3?M),and I-32(IC₅₀=1.6?M),1.7?M)showed certain inhibitory activity against breast cancer cell line MCF-7 and colorectal cancer cell line HCT 116,which have the potential to be further developed as CDK2 inhibitors for the preclinical studies.