Heterobiaryl purine derivatives as potent antiproliferative agents: Inhibitors of cyclin dependent kinases. Part II (original) (raw)
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Annals of the New York Academy of Sciences, 1999
The frequent deregulation of cell cycle progression in cancer 1 has prompted an active search for kinase inhibitors with high affinity and specificity for cyclin-dependent kinases (Cdks). Three major classes of Cdk-targeting drugs have been identified to date, including butyrolactone I, 2 polyhydroxylated flavones such as flavopiridol, 3 and substituted purines. 4 The first substituted purine derivative acting as a selective Cdk inhibitor, olomoucine, has been identified from screening against Cdk1/cyclin B complex. 5 Olomoucine competitively inhibits Cdk1, Cdk2, Cdk5, and, to a lesser extent, Erk1. 5 Recent results have pointed to unexpected pharmacologic properties of 2,6,9trisubstituted purines derived from the olomoucine lead structure. 6,7 To investigate the question in more detail, we developed a program for synthesis and evaluation of new compounds in this series. Twenty-seven derivatives were synthesized and assayed for specific inhibition of Cdk1/cyclin B from starfish oocytes and human recombinant Cdk5/p35 complex. In agreement with earlier results, 5 data showed that a strong correlation exists between inhibitory efficiencies against Cdk1 and Cdk5. In contrast, all compounds were only marginally active against Erk1 and Erk2 kinases. One compound in the series, ML-1437, proved much more active than olomoucine against purified Cdk1/cyclin B, Cdk5/p35, and Cdk2/cyclin E. It also showed pronounced cytotoxicity against human cervix carcinoma HeLa cells in vitro, even on short exposure. Growing IMR-90 (human normal fibroblasts), LoVo (human colon adenocarcinoma), and SQ-20B (human head and neck squamous carcinoma) cells gave similar results, but drug resistance increased rapidly as cells (SQ-20B and IMR-90) reached confluence. These results suggest that the affinity for Cdks and the cytotoxic potential of the drugs are interrelated (FIG. 1, TABLE 1). With the exception of pronounced lengthening of S phase transit during early-S in synchronized HeLa cells, ML-1437 at subtoxic concentration proved unable to produce reversible arrest of the cell cycle progression. When observed, arrest in the G1 and G2 phases of the cell cycle correlated with induced cell death, and chronic exposure to lethal doses of the drug resulted in massive micronucleation in relation to mitotic cell death, with no evidence of endoreduplication (polyploidization) or apd
4Alkoxy2,6-diaminopyrimidine derivatives: inhibitors of cyclin dependent kinases 1 and 2
Bioorganic & Medicinal Chemistry Letters, 2003
The cyclin dependent kinase (cdk) inhibitor NU6027, 4-cyclohexylmethoxy-5-nitroso-pyrimidine-2,6-diamine (IC 50 vs cdk1/cyclinB1=2.9 AE 0.1 mM and IC 50 vs cdk2/cyclinA3=2.2 AE0.6 mM), was used as the basis for the design of a series of 4-alkoxy-2,6-diamino-5-nitrosopyrimidine derivatives. The synthesis and evaluation of 21 compounds as potential inhibitors of cyclindependent kinases 1 and 2 is described and the structure-activity relationships relating to NU6027 have been probed. Simple alkoxy-or cycloalkoxy-groups at the O 4 -position were tolerated, with the 4-(2-methylbutoxy)-derivative (IC 50 vs cdk1/ cyclinB1=12 AE2 mM and cdk2/cyclinA3=13 AE 4 mM) retaining significant activity. Substitutions at the N 6 position were not tolerated. Replacement of the 5-nitroso substituent with ketone, oxime and semicarbazone groups essentially abolished activity. However, the derivative bearing an isosteric 5-formyl group, 2,6-diamino-4-cyclohexylmethoxy-pyrimidine-5-carbaldehyde, showed modest activity (IC 50 vs cdk1/cyclinB1=35 AE3 mM and cdk2/cyclinA3=43 AE 3 mM). The X-ray crystal structure of the 5-formyl compound bound to cdk2 has been determined to 2.3 Å resolution. The intramolecular H-bond deduced from the structure with NU6027 bound to cdk2 is not evident in the structure with the corresponding formyl compound. Thus the parent compound, 4cyclohexylmethoxy-5-nitrosopyrimidine-2,6-diamine (NU6027), remains the optimal basis for future structure-activity studies for cyclin-dependent kinase inhibitors in this series. #
2,6,8,9-Tetrasubstituted Purines as New CDK1 Inhibitors
Bioorganic & Medicinal Chemistry Letters, 2003
Purine inhibitors of cyclin-dependent kinases attract attention as potential anticancer drugs because their first representative roscovitine recently entered clinical trials. Although well described in terms of structure-activity relationships, we still present here a novel modification of the purine scaffold influencing their inhibitory properties. The introduced C-8 substituents, however, lowered the CDK inhibitory activity of roscovitine, whereas the antiproliferative potential of several derivatives remained high.
Cyclin-dependent kinase inhibition is considered a promising target for cancer treatment for its crucial role in cell cycle regulation. Pyrazolo pyrimidine derivatives were well established for their antitumor activity via CDK2 inhibition. In this research, new series of pyrazolopyrimidine derivatives (4-15) was designed and synthesised as novel CDK2 inhibitors. The anti-proliferative activities against MCF-7, HCT-116, and HepG-2 were used to evaluate their anticancer activity as novel CDK2 inhibitors. Most of the compounds showed superior cytotoxic activity against MCF-7 and HCT-116 compared to Sorafenib. Only compounds 8, 14, and 15 showed potent activity against HepG-2. The CDK2/cyclin A2 enzyme inhibitory activity was tested for all synthesised compounds. Compound 15 showed the most significant inhibitory activity with IC 50 0.061 ± 0.003 mM. It exerted remarkable alteration in Pre G1 and S phase cell cycle progression and caused apoptosis in HCT cells. In addition, the normal cell line cytotoxicity for compound 15 was assigned revealing low cytotoxic results in normal cells rather than cancer cells. Molecular docking was achieved on the designed compounds and confirmed the two essential hydrogen binding with Leu83 in CDK2 active site. In silico ADMET studies and drug-likeness showed proper pharmacokinetic properties which helped in structure requirements prediction for the observed antitumor activity.
Journal of Medicinal Chemistry, 2014
The success of imatinib, a BCR-ABL inhibitor for the treatment of chronic myelogenous leukemia, has created a great impetus for the development of additional kinase inhibitors as therapeutic agents. However, the complexity of cancer has led to recent interest in polypharmacological approaches for developing multikinase inhibitors with low toxicity profiles. With this goal in mind, we analyzed more than 150 novel cyano pyridopyrimidine compounds and identified structure−activity relationship trends that can be exploited in the design of potent kinase inhibitors. One compound, 8cyclopentyl-2-[4-(4-methyl-piperazin-1-yl)-phenylamino]-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidine-6-carbonitrile (7x), was found to be the most active, inducing apoptosis of tumor cells at a concentration of approximately 30−100 nM. In vitro kinase profiling revealed that 7x is a multikinase inhibitor with potent inhibitory activity against the CDK4/CYCLIN D1 and ARK5 kinases. Here, we report the synthesis, structure−activity relationship, kinase inhibitory profile, in vitro cytotoxicity, and in vivo tumor regression studies by this lead compound.
Bioorganic & Medicinal Chemistry, 2010
A series of novel purine and pyrimidine derivatives were prepared and biologically evaluated for their in vitro anti-CDK2/cyclin A3 and antitumor activities in Ehrlich ascites carcinoma (EAC) cell based assay. The novel purine derivatives 13a,b demonstrated potent inhibitor activities with IC50 values of 14 ± 9 and 13 ± 9 μM, respectively. Additionally, compound 15a showed the highest potency (IC50 = 10 ± 6 μM) in EAC cell based assay. Molecular modeling study, including fitting to a 3D-pharmacophore model and their docking into cyclin dependant kinase2 (CDK2) active site showed high fit values and docking scores.The manuscript describes the investigation of a series of novel purine and pyrimidine derivatives, which were prepared in good yield by using diaminomaleonitrile and tosylisocyanate in acetonitrile. Molecular modeling studies, including fitting to a 3D-pharmacophore model their docking into cycline-dependent kinase2 (CDK2) active site were performed to understand the structural features of CDK2 inhibitors. Biological evaluation for both in vitro CDK2/cyclinA3 inhibition activity and antitumor activity in Ehrlich ascites carcinoma (EAC) cell based assay were also carried out.
N-&-N, a new class of cell death-inducing kinase inhibitors derived from the purine roscovitine
Molecular Cancer Therapeutics, 2008
Cyclin-dependent kinases (CDKs) and their regulators show frequent abnormalities in tumors. Ten low molecular weight pharmacologic inhibitors of CDKs are currently in clinical trials against various cancers, including the 2,6,9-trisubstituted purine (R)-roscovitine (CYC202/Seliciclib). We here report the characterization of N-&-N1, a bioisoster of roscovitine displaying improved antitumoral properties. N-&-N1 shows exquisite selectivity for CDKs, with 2-to 3-fold enhanced potency compared with (R)roscovitine. Inhibition of retinoblastoma protein phosphorylation and RNA polymerase II Ser 2 phosphorylation in neuroblastoma SH-SY5Y cells exposed to N-&-N1 indicates that N-&-N1 is able to inhibit CDKs in a cellular context. N-&-N1 also down-regulates the expression of RNA polymerase. Cocrystal structures of N-&-N1 and (R)roscovitine in complex with CDK2/cyclin A reveal that both inhibitors adopt similar binding modes. A competitive assay shows that, compared with (R)-roscovitine, N-&-N1 has reduced affinity for Erk2 and pyridoxal kinase. N-&-N1 triggers cell death in a panel of diverse cell lines. Cell death is accompanied by events characteristic of apoptosis: cytochrome c release, activation of effector caspases, and poly(ADP-ribose) polymerase cleavage. Induction of p53 and p21 CIP1 and down-regulation of the Mcl-1 antiapoptotic factor were also observed. Studies in mice show that N-&-N1 has pharmacokinetics properties similar to those of (R)-roscovitine. Altogether, these results show that analogues of (R)-roscovitine can be designed with improved antitumor potential.