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1.
J Exp Bot ; 2024 May 22.
Article in English | MEDLINE | ID: mdl-38776394

ABSTRACT

Cytokinin oxidase/dehydrogenase (CKX) inhibitors reduce the degradation of cytokinins in plants and thereby may improve the efficiency of agriculture and plant tissue culture-based practices. Here, we report a synthesis and structure-activity relationship study of novel urea derivatives concerning their CKX inhibitory activity. The best compounds showed sub-nanomolar IC50 values with maize ZmCKX1, the lowest value yet documented. Other CKX isoforms of maize (Zea mays) and Arabidopsis were also inhibited very effectively. The binding mode of four compounds was characterized based on high-resolution crystal complex structures. Using the soil nematode Caenorhabditis elegans, and human skin fibroblasts, key CKX inhibitors with low toxicity were identified. These compounds enhanced the shoot regeneration of Lobelia, Drosera, and Plectranthus, as well as the growth of Arabidopsis and Brassica napus. At the same time, a key compound (namely 82), activated a cytokinin primary response gene ARR5:GUS and cytokinin sensor TCSv2:GUS, without activating the Arabidopsis cytokinin receptors AHK3 and AHK4. This strongly implies that the effect of compound 82 is due to the upregulation of cytokinin signalling. Overall, this work presents highly effective and easily prepared CKX inhibitors with a low risk of environmental toxicity for further investigation of their potential in agriculture and biotechnology.

2.
J Glob Antimicrob Resist ; 33: 114-119, 2023 06.
Article in English | MEDLINE | ID: mdl-36906171

ABSTRACT

OBJECTIVES: This study aimed to characterise compounds with activity against carbapenemase-expressing Gram-negative bacteria and nematodes and evaluate their cytotoxicity to non-cancerous human cells. METHODS: The antimicrobial activity and toxicity of a series of phenyl-substituted urea derivatives were evaluated using broth microdilution, chitinase, and resazurin reduction assays. RESULTS: The effects of different substitutions present on the nitrogen atoms of the urea backbone were investigated. Several compounds were active against Staphylococcus aureus and Escherichia coli control strains. Specifically, derivatives 7b, 11b, and 67d exhibited antimicrobial activity against Klebsiella pneumoniae 16, a carbapenemase-producing Enterobacteriaceae species, with minimum inhibitory concentration (MIC) values of 100, 50, and 72 µM (32, 64, and 32 mg/L), respectively. In addition, the MICs obtained against a multidrug-resistant E. coli strain were 100, 50, and 36 µM (32, 16, and 16 mg/L) for the same compounds, respectively. Furthermore, the urea derivatives 18b, 29b, 50c, 51c, 52c, 55c-59c, and 62c were very active towards the nematode Caenorhabditis elegans. CONCLUSIONS: Testing on non-cancerous human cell lines suggested that some of the compounds have the potential to affect bacteria, especially helminths, with limited cytotoxicity to humans. Given the simplicity of synthesis for this class of compounds and their potency against Gram-negative, carbapenemase-expressing K. pneumoniae, aryl ureas possessing the 3,5-dichloro-phenyl group certainly warrant further investigation to exploit their selectivity.


Subject(s)
Anthelmintics , Anti-Infective Agents , Humans , Anti-Bacterial Agents/pharmacology , Escherichia coli , Anti-Infective Agents/pharmacology , Bacteria , Anthelmintics/pharmacology
3.
Phytochemistry ; 205: 113481, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36283448

ABSTRACT

Isoprenoid cytokinins are a class of naturally occurring plant signaling molecules. A series of prepared compounds derived from isoprenoid cytokinins (isopentenyladenine, trans-zeatin and cis-zeatin) with attached 2'-deoxy-d-ribose or 2',3'-dideoxy-d-ribose at the N9 position of the purine were prepared and their biological activities were examined. Different synthetic approaches were employed. The final compounds were characterized with variety of physicochemical methods (TLC, HPLC-MS, and NMR) and their cytokinin activity was determined in classical bioassays such as Amaranthus, tobacco callus, detached wheat leaf senescence and Arabidopsis thaliana root elongation inhibition assay. In addition, compounds were screened for activation of the cytokinin signaling pathway (bacterial receptor, competitive ligand binding and ARR5::GUS assay) to provide a detailed assessment of CK structure-activity relationship. The prepared compounds were found to be non-toxic to human cells and the majority of assays exhibited the highest activity of free bases while 2',3'-dideoxyribosides had very weak or no activity. In contrast to the free bases, all 2'-deoxyriboside derivatives were not toxic to tobacco callus even at the highest tested concentration (10-4 moL/l) and compound 1 (iPdR) induced betacyanin synthesis at higher concentration even stronger than iP free base in the Amaranthus bioassay. The general cytokinin activity pattern base > riboside >2'-deoxyriboside > 2',3'-dideoxyriboside was distinguished.


Subject(s)
Cytokinins , Terpenes , Humans , Cytokinins/pharmacology , Ribose
5.
J Agric Food Chem ; 70(23): 7288-7301, 2022 Jun 15.
Article in English | MEDLINE | ID: mdl-35658447

ABSTRACT

Solubility of growth regulators is essential for their use in agriculture. Four new cytokinin salts─6-benzylaminopurine mesylate (1), 6-(2-hydroxybenzylamino)purine mesylate (2), 6-(3-hydroxybenzylamino)purine mesylate (3), and 6-(3-methoxybenzylamino)purine mesylate (4)─were synthesized, and their crystal structures were determined to clarify structural influence on water solubility. The mesylates were several orders of magnitude more water-soluble than the parent CKs. The new salts significantly reduced chlorophyll degradation and impairment of photosystem II functionality in barley leaf segments undergoing artificial senescence and had pronounced effects on the leaves' endogenous CK pools, maintaining high concentrations of functional metabolites for several days, unlike canonical CKs. A foliar treatment with 1 and 3 increased the harvest yield of spring barley by up to 8% when compared to treatment with the parent CKs while also increasing the number of productive tillers. This effect was attributed to the higher bioavailability of the mesylate salts and the avoidance of dimethyl sulfoxide exposure.


Subject(s)
Cytokinins , Hordeum , Cytokinins/metabolism , Cytokinins/pharmacology , Hordeum/metabolism , Mesylates/metabolism , Photosynthesis , Plant Leaves/metabolism , Salts , Water/metabolism
6.
Arch Pharm (Weinheim) ; 354(6): e2100001, 2021 Jun.
Article in English | MEDLINE | ID: mdl-33733468

ABSTRACT

A small library of 2-[(1H-indol-3-yl)methyl]-5-(alkylthio)-1,3,4-oxadiazoles was prepared, starting from indole-3-acetic acid methyl ester and its 5-methyl-substituted derivative. The synthetic route involved the formation of intermediate hydrazides, their condensation with carbon disulfide, and intramolecular cyclization to corresponding 5-[(1H-indol-3-yl)methyl]-1,3,4-oxadiazole-2(3H)-thiones. The latter were then S-alkylated, and in case of ester derivatives, they were further hydrolyzed into corresponding carboxylic acids. All 5-[(1H-indol-3-yl)methyl]-1,3,4-oxadiazole-2(3H)-thiones and their S-alkylated derivatives were then screened for their protective effects in vitro and in vivo. Methyl substitution on the indole ring and propyl, butyl, or benzyl substitution on sulfhydryl group-possessing compounds were revealed to protect Friedreich's ataxia fibroblasts against the effects of glutathione depletion induced by the γ-glutamylcysteine synthetase inhibitor, buthionine sulfoximine. Two of the active compounds also reproducibly increased the survival of Caenorhabditis elegans exposed to juglone-induced oxidative stress.


Subject(s)
Antioxidants , Indoles , Oxadiazoles , Oxidative Stress/drug effects , Thiones , Acetates/chemical synthesis , Animals , Antioxidants/chemical synthesis , Antioxidants/chemistry , Antioxidants/pharmacology , Caenorhabditis elegans , Cells, Cultured , Friedreich Ataxia/drug therapy , Friedreich Ataxia/metabolism , Friedreich Ataxia/pathology , Humans , Indoleacetic Acids/chemistry , Indoles/chemistry , Indoles/pharmacology , Oxadiazoles/chemical synthesis , Oxadiazoles/chemistry , Oxadiazoles/pharmacology , Structure-Activity Relationship , Thiones/chemical synthesis , Thiones/chemistry , Thiones/pharmacology
7.
Bioorg Med Chem ; 33: 115993, 2021 03 01.
Article in English | MEDLINE | ID: mdl-33497938

ABSTRACT

Kinetin (N6-furfuryladenine), a plant growth substance of the cytokinin family, has been shown to modulate aging and various age-related conditions in animal models. Here we report the synthesis of kinetin isosteres with the purine ring replaced by other bicyclic heterocycles, and the biological evaluation of their activity in several in vitro models related to neurodegenerative diseases. Our findings indicate that kinetin isosteres protect Friedreich́s ataxia patient-derived fibroblasts against glutathione depletion, protect neuron-like SH-SY5Y cells from glutamate-induced oxidative damage, and correct aberrant splicing of the ELP1 gene in fibroblasts derived from a familial dysautonomia patient. Although the mechanism of action of kinetin derivatives remains unclear, our data suggest that the cytoprotective activity of some purine isosteres is mediated by their ability to reduce oxidative stress. Further, the studies of permeation across artificial membrane and model gut and blood-brain barriers indicate that the compounds are orally available and can reach central nervous system. Overall, our data demonstrate that isosteric replacement of the kinetin purine scaffold is a fruitful strategy for improving known biological activities of kinetin and discovering novel therapeutic opportunities.


Subject(s)
Kinetin/pharmacology , Purines/pharmacology , Cell Survival/drug effects , Cells, Cultured , Cytoprotection , Dose-Response Relationship, Drug , Humans , Kinetin/chemical synthesis , Kinetin/chemistry , Molecular Structure , Oxidative Stress/drug effects , Purines/chemical synthesis , Purines/chemistry , Structure-Activity Relationship
8.
Mol Divers ; 24(4): 1025-1042, 2020 Nov.
Article in English | MEDLINE | ID: mdl-31713185

ABSTRACT

A series of benzopyrano[2,3-c]pyrazol-4(2H)-one derivatives were synthesized from readily available 1-phenyl- and 1-methyl-1H-pyrazol-3-ols by sequentially employing O-acylation, Fries rearrangement and potassium carbonate-induced cyclization. The anthelmintic properties of the obtained compounds were investigated in vivo in a model nematode, Caenorhabditis elegans. Five compounds, namely 2-phenyl[1]benzopyrano[2,3-c]pyrazol-4(2H)-one 33 and its 7-fluoro, 7-chloro-, 7-bromo- and 8-fluoro-analogues, 36, 38, 40 and 43, respectively, altered the development of C. elegans. While the activities of 33 and 43 were rather modest, compounds 36, 38 and 40 inhibited the growth of the worms at concentrations of approximately 1-3 µM. At these concentrations, the compounds did not kill the worms, but they strongly inhibited their development, with the majority of larvae never progressing past the L1 stage. Moreover, testing in non-cancer human cell lines showed that, with exception of 7-bromo derivative 40, the active compounds have favourable toxicity profiles.


Subject(s)
Anthelmintics/chemical synthesis , Anthelmintics/pharmacology , Pyrazoles/chemistry , Animals , Caenorhabditis elegans/drug effects , Cell Line , Cyclization/drug effects , Humans , Larva/drug effects , Structure-Activity Relationship
9.
Bioorg Med Chem ; 28(2): 115230, 2020 01 15.
Article in English | MEDLINE | ID: mdl-31862308

ABSTRACT

Cytokinins are naturally occurring substances that act as plant growth regulators promoting plant growth and development, including shoot initiation and branching, and also affecting apical dominance and leaf senescence. Aromatic cytokinin 6-benzylaminopurine (BAP) has been widely used in micropropagation systems and biotechnology. However, its 9-glucoside (BAP9G) accumulates in explants, causing root inhibition and growth heterogenity. To overcome BAP disadvantages, a series of ring-substituted 2'-deoxy-9-(ß)-d-ribofuranosylpurine derivatives was prepared and examined in different classical cytokinin bioassays. Amaranthus, senescence and tobacco callus bioassays were employed to provide details of cytokinin activity of 2'-deoxy-9-(ß)-d-ribosides compared to their respective free bases and ribosides. The prepared derivatives were also tested for their recognition by cytokinin receptors of Arabidopsis thaliana AHK3 and CRE1/AHK4. The ability of aromatic N6-substituted adenine-2'-deoxy-9-(ß)-d-ribosides to promote plant growth and delay senescence was increased considerably and, in contrast to BAP, no loss of cytokinin activity at higher concentrations was observed. The presence of a 2'-deoxyribosyl moiety at the N9-position led to an increase in cytokinin activities in comparison to the free bases and ribosides. The antioxidant capacity, cytotoxicity and effect on the MHV-68 gammaherpesvirus strain were also examined.


Subject(s)
Antioxidants/pharmacology , Arabidopsis/drug effects , Plant Growth Regulators/pharmacology , Purine Nucleosides/pharmacology , Animals , Antioxidants/chemical synthesis , Antioxidants/chemistry , Arabidopsis/metabolism , Chlorocebus aethiops , Dose-Response Relationship, Drug , Molecular Structure , Plant Growth Regulators/chemical synthesis , Plant Growth Regulators/chemistry , Purine Nucleosides/chemical synthesis , Purine Nucleosides/chemistry , Structure-Activity Relationship , Vero Cells
10.
Ageing Res Rev ; 55: 100958, 2019 11.
Article in English | MEDLINE | ID: mdl-31479763

ABSTRACT

It has been more than 60 years since the discovery of kinetin, the first known member of a group of plant hormones called cytokinins. In this review we summarize the health-promoting activity of kinetin in animal systems, ranging from cells cultured in vitro through invertebrates to mammals. Kinetin has been shown to modulate aging, to delay age-related physiological decline and to protect against some neurodegenerative diseases. We also review studies on its mechanism of action, as well as point out gaps in our current knowledge.


Subject(s)
Aging , Healthy Aging , Kinetin/therapeutic use , Animals , Cytokinins , Humans , Kinetin/pharmacology
11.
Bioorg Chem ; 90: 103005, 2019 09.
Article in English | MEDLINE | ID: mdl-31271944

ABSTRACT

Rho-associated serine/threonine kinases (ROCKs) are principal regulators of the actin cytoskeleton that regulate the contractility, shape, motility, and invasion of cells. We explored the relationships between structure and anti-ROCK2 activity in a group of purine derivatives substituted at the C6 atom by piperidin-1-yl or azepan-1-yl groups. Structure-activity relationship (SAR) analyses suggested that anti-ROCK activity is retained, and may be further increased, by substitution of the parent compounds at the C2 atom or by expansion of the C6 side chain. These inhibitors of ROCK can reach effective concentrations within cells, as demonstrated by a decrease in phosphorylation of the ROCK target MLC, and by inhibition of the ROCK-dependent invasion of melanoma cells in the collagen matrix. Our study may be useful for further optimization of C6-substituted purine inhibitors of ROCKs and of other sensitive kinases identified by the screening of a broad panel of protein kinases.


Subject(s)
Antineoplastic Agents/pharmacology , Protein Kinase Inhibitors/pharmacology , Purines/pharmacology , rho-Associated Kinases/antagonists & inhibitors , Antineoplastic Agents/chemical synthesis , Cell Line, Tumor , Cell Movement/drug effects , Cell Proliferation/drug effects , Humans , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Purines/chemical synthesis , Signal Transduction/drug effects , Structure-Activity Relationship
12.
J Med Chem ; 61(20): 9105-9120, 2018 10 25.
Article in English | MEDLINE | ID: mdl-30234987

ABSTRACT

Cyclin-dependent kinases (CDKs) are an important and emerging class of drug targets for which many small-molecule inhibitors have been developed. However, there is often insufficient data available on the selectivity of CDK inhibitors (CDKi) to attribute the effects on the presumed target CDK to these inhibitors. Here, we highlight discrepancies between the kinase selectivity of CDKi and the phenotype exhibited; we evaluated 31 CDKi (claimed to target CDK1-4) for activity toward CDKs 1, 2, 4, 5, 7, 9 and for effects on the cell cycle. Our results suggest that most CDKi should be reclassified as pan-selective and should not be used as a tool. In addition, some compounds did not even inhibit CDKs as their primary cellular targets; for example, NU6140 showed potent inhibition of Aurora kinases. We also established an online database of commercially available CDKi for critical evaluation of their utility as molecular probes. Our results should help researchers select the most relevant chemical tools for their specific applications.


Subject(s)
Cell Cycle/drug effects , Cyclin-Dependent Kinases/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , HCT116 Cells , Humans , Quinolines/pharmacology , Thiazoles/pharmacology
13.
Eur J Med Chem ; 150: 946-957, 2018 Apr 25.
Article in English | MEDLINE | ID: mdl-29604584

ABSTRACT

Eleven 6-furfurylaminopurine (kinetin, Kin) derivatives were synthesized to obtain biologically active compounds. The prepared compounds were characterized using 1H NMR, mass spectrometry combined with HPLC purity determination and elemental C, H, N analyses. The biological activity of new derivatives was tested on plant cells and tissues in cytokinin bioassays, such as tobacco callus, detached wheat leaf chlorophyll retention bioassay and Amaranthus bioassay. The selected compounds were subsequently tested on normal human dermal fibroblasts (NHDF) and keratinocyte cell lines (HaCaT) to exclude possible phototoxic effects and, on the other hand, to reveal possible UVA and UVB photoprotective activity. The protective antioxidant activity of the prepared cytokinin derivatives was further studied and compared to previously prepared antisenescent compound 6-furfurylamino-9-(tetrahydrofuran-2-yl)purine (Kin-THF) using induced oxidative stress (OS) on nematode Caenorhabditis elegans damaged by 5-hydroxy-1,4-naphthoquinone (juglone), a generator of reactive oxygen species. The observed biological activity was interpreted in relation to the structure of the prepared derivatives. The most potent oxidative stress protection of all the prepared compounds was shown by 6-(thiophen-2-ylmethylamino)-9-(tetrahydrofuran-2-yl)purine (6) and 2-chloro-6-furfurylamino-9-(tetrahydrofuran-2-yl)purine (9) derivatives and the results were comparable to Kin-THF. Compounds 6 and 9 were able to significantly protect human skin cells against UV radiation in vitro. Both the derivatives 6 and 9 showed higher protective activity in comparison to previously known structurally similar compounds Kin and Kin-THF. The obtained results are surprising due to the fact that the prepared compounds showed to be inactive in the ORAC assay which proved that the compounds did not act as direct antioxidants as they were unable to directly scavenge oxygen radicals.


Subject(s)
Cytokinins/pharmacology , Oxidative Stress/drug effects , Protective Agents/pharmacology , Skin/drug effects , Ultraviolet Rays , Cytokinins/chemical synthesis , Cytokinins/chemistry , Dose-Response Relationship, Drug , Humans , Molecular Structure , Protective Agents/chemical synthesis , Protective Agents/chemistry , Structure-Activity Relationship
14.
Biogerontology ; 19(2): 109-120, 2018 04.
Article in English | MEDLINE | ID: mdl-29255944

ABSTRACT

Cytokinins are phytohormones that are involved in many processes in plants, including growth, differentiation and leaf senescence. However, they also have various activities in animals. For example, kinetin and trans-zeatin can reduce levels of several aging markers in human fibroblasts. Kinetin can also protect mice against oxidative and glyoxidative stress, and prolong fruit flies' lifespan. Additionally, several cytokinins are currently used in cosmetics. To extend knowledge of the breadth of cytokinins' activities, we examined effects of natural cytokinin bases on the model nematode Caenorhabditis elegans. We found that kinetin, para-topolin and meta-topolin prolonged the lifespan of C. elegans. Kinetin also protected the organism against oxidative and heat stress. Furthermore, our results suggest that presence of reactive oxygen species, but not DAF-16 (the main effector of the insulin/insulin-like growth factor signaling pathway), is required for the beneficial effects of kinetin. Ultra-high performance liquid chromatography-tandem mass spectrometric analysis showed that kinetin is unlikely to occur naturally in C. elegans, but the worm efficiently absorbs and metabolizes it into kinetin riboside and kinetin riboside-5'-monophosphate.


Subject(s)
Caenorhabditis elegans/drug effects , Cytokinins/pharmacology , Longevity/drug effects , Plant Growth Regulators/pharmacology , Animals , Caenorhabditis elegans/genetics , Caenorhabditis elegans/physiology , Caenorhabditis elegans Proteins/genetics , Caenorhabditis elegans Proteins/metabolism , Cytokinins/pharmacokinetics , Forkhead Transcription Factors/genetics , Forkhead Transcription Factors/metabolism , Heat-Shock Response/drug effects , Insulin/metabolism , Kinetin/pharmacokinetics , Kinetin/pharmacology , Longevity/physiology , Mutation , Oxidative Stress/drug effects , Plant Growth Regulators/pharmacokinetics , Reactive Oxygen Species/metabolism , Signal Transduction/drug effects , Thermotolerance/drug effects
15.
Phytochemistry ; 136: 156-164, 2017 Apr.
Article in English | MEDLINE | ID: mdl-28153445

ABSTRACT

Cytokinin ribosides (N6-substituted adenosines) have demonstrated anticancer activity in various cultured cell lines, several xenografts and even a small clinical trial. Effects of kinetin riboside, N6-benzyladenosine (BAR) and N6-isopentenyladenosine on various parameters related to apoptosis have also been reported, but not directly compared with those of the highly active naturally occurring aromatic cytokinins oTR (ortho-topolin riboside) and 2OH3MeOBAR (N6-(2-hydroxy-3-methoxybenzyl)adenosine). Here we show that 2OH3MeOBAR is the most active cytokinin riboside studied to date (median, 1st quartile, 3rd quartile and range of GI50 in tests with the NCI60 cell panel: 0.19, 0.10, 0.43 and 0.02 to 15.7 µM, respectively) and it differs from other cytokinins by inducing cell death without causing pronounced ATP depletion. Analysis of NCI60 test data suggests that its activity is independent of p53 status. Further we demonstrate that its 5'-monophosphate, the dominant cancer cell metabolite, inhibits the candidate oncogene DNPH1. Synthesis, purification, HPLC-MS identification and HPLC-UV quantification of 2OH3MeOBAR metabolites are also reported.


Subject(s)
Adenosine/pharmacology , Cytokinins/pharmacology , Adenosine/analogs & derivatives , Adenosine/chemistry , Apoptosis/drug effects , Cell Death/drug effects , Cytokinins/chemistry , Glycosides/pharmacology , Isopentenyladenosine/pharmacology , Kinetin/pharmacology , Molecular Structure
16.
Phytochemistry ; 135: 115-127, 2017 Mar.
Article in English | MEDLINE | ID: mdl-27986278

ABSTRACT

Naturally occurring cytokinins are adenine-based plant hormones. Although, the effect of various substituents at positions N1, C2, N3, N6, N7, or N9 on the biological activity of cytokinins has been studied, the C8-substituted compounds have received little attention. Here, we report the synthesis and in vitro biological testing of thirty-one cytokinin derivatives substituted at the C8 position of the adenine skeleton and twenty-seven compounds which served as their N9-tetrahydropyranyl protected precursors. The cytokinin activity of all the compounds was determined in classical cytokinin biotests (wheat leaf senescence, Amaranthus and tobacco callus assays). With some exceptions, the compounds with a N9-tetrahydropyranyl group were generally less active than their de-protected analogs. The latter were further tested for their ability to activate the Arabidopsis cytokinin receptors AHK3 and CRE1/AHK4 in bacterial receptor activation assays. Using this approach, we identified derivatives bearing short aliphatic chains and retaining high cytokinin activity. Such compounds are suitable candidates for fluorescence labeling or as protein-affinity ligands. We further found that some C8-substituted cytokinins exhibited no or lower cytotoxicity toward tobacco cells when compared to their parent compound. Therefore, we also present and discuss the cytotoxicity of all the compounds against three normal human cell lines.


Subject(s)
Arabidopsis/chemistry , Cytokinins , Adenine/analogs & derivatives , Adenine/chemistry , Cytokinins/chemical synthesis , Cytokinins/chemistry , Cytokinins/metabolism , Drug Screening Assays, Antitumor , Humans , Plant Growth Regulators/metabolism , Protein Kinases/metabolism , Structure-Activity Relationship
17.
J Proteome Res ; 15(12): 4505-4517, 2016 12 02.
Article in English | MEDLINE | ID: mdl-27794614

ABSTRACT

Replication stress (RS) fuels genomic instability and cancer development and may contribute to aging, raising the need to identify factors involved in cellular responses to such stress. Here, we present a strategy for identification of factors affecting the maintenance of common fragile sites (CFSs), which are genomic loci that are particularly sensitive to RS and suffer from increased breakage and rearrangements in tumors. A DNA probe designed to match the high flexibility island sequence typical for the commonly expressed CFS (FRA16D) was used as specific DNA affinity bait. Proteins significantly enriched at the FRA16D fragment under normal and replication stress conditions were identified using stable isotope labeling of amino acids in cell culture-based quantitative mass spectrometry. The identified proteins interacting with the FRA16D fragment included some known CFS stabilizers, thereby validating this screening approach. Among the hits from our screen so far not implicated in CFS maintenance, we chose Xeroderma pigmentosum protein group C (XPC) for further characterization. XPC is a key factor in the DNA repair pathway known as global genomic nucleotide excision repair (GG-NER), a mechanism whose several components were enriched at the FRA16D fragment in our screen. Functional experiments revealed defective checkpoint signaling and escape of DNA replication intermediates into mitosis and the next generation of XPC-depleted cells exposed to RS. Overall, our results provide insights into an unexpected biological role of XPC in response to replication stress and document the power of proteomics-based screening strategies to elucidate mechanisms of pathophysiological significance.


Subject(s)
DNA Repair/physiology , DNA Replication/physiology , DNA-Binding Proteins/physiology , Proteomics/methods , Cell Cycle Checkpoints , Chromatography, Affinity , Chromosome Fragile Sites , Humans , Xeroderma Pigmentosum
18.
Eur J Med Chem ; 62: 443-52, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23399722

ABSTRACT

A series of 2,9-substituted 6-guanidinopurines, structurally related to the cyclin-dependent kinase (CDK) inhibitors olomoucine and roscovitine, has been synthesized and characterized. A new copper-catalyzed method for the synthesis of 2-substituted 6-guanidino-9-isopropylpurines under mild reaction conditions has been developed. All prepared compounds were screened for their CDK1 and CDK2 inhibitory activities, cytotoxicity and antiproliferative effects in the breast cancer-derived cell line MCF7. The most active derivative 16g possessed an identical side chain in the C2 position to roscovitine; this compound displayed approximately five fold higher inhibitory activity towards CDK2/cyclin E and more than ten fold increase in cytotoxicity in MCF7 cells. Interestingly and in contrast to previously described findings, (S)-6-guanidinopurine derivatives were generally more active than their (R)-counterparts. Kinase selectivity profiling of (R)- and (S)-enantiomers 16e and 16g, respectively, revealed that introduction of a guanidino group at the C6 position of the purine moiety decreased selectivity towards protein kinases compared to roscovitine. Nevertheless, increased inhibitory activity and decreased selectivity offer a good starting point for further development of new protein kinase inhibitors.


Subject(s)
Antineoplastic Agents/pharmacology , CDC2 Protein Kinase/antagonists & inhibitors , Cyclin-Dependent Kinase 2/antagonists & inhibitors , Guanidine/pharmacology , Protein Kinase Inhibitors/pharmacology , Purines/pharmacology , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , CDC2 Protein Kinase/metabolism , Cell Cycle/drug effects , Cell Proliferation/drug effects , Cyclin-Dependent Kinase 2/metabolism , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Guanidine/analogs & derivatives , Guanidine/chemical synthesis , Humans , MCF-7 Cells , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/chemistry , Purines/chemical synthesis , Purines/chemistry , Structure-Activity Relationship
19.
Eur J Med Chem ; 61: 61-72, 2013 Mar.
Article in English | MEDLINE | ID: mdl-22770608

ABSTRACT

Several inhibitors of cyclin-dependent kinases (CDKs), including the 2,6,9-trisubstituted purine derivative roscovitine, are currently being evaluated in clinical trials as potential anticancer drugs. Here, we describe a new series of roscovitine derivatives that show increased potency in vitro. The series was tested for cytotoxicity against six cancer cell lines and for inhibition of CDKs. For series bearing 2-(hydroxyalkylamino) moiety, cytotoxic potency strongly correlated with anti-CDK2 activity. Importantly, structural changes that increase biochemical and anticancer activities of these compounds also increase elimination half-life. The most potent compounds were investigated further to assess their ability to influence cell cycle progression, p53-regulated transcription and apoptosis. All the observed biological effects were consistent with inhibition of CDKs involved in the regulation of cell cycle and transcription.


Subject(s)
Cyclin-Dependent Kinases/antagonists & inhibitors , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , Purines/chemistry , Purines/pharmacology , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Cell Proliferation/drug effects , Cyclin-Dependent Kinases/metabolism , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , HCT116 Cells , Humans , K562 Cells , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemistry , Purines/chemical synthesis , Structure-Activity Relationship
20.
Eur J Med Chem ; 46(9): 4289-94, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21777997

ABSTRACT

Small molecule inhibitors of cyclin-dependent kinases (CDK) have been developed as anticancer drugs with cytostatic and cytotoxic properties, but some of them have also been shown to limit angiogenesis. Here, we report that the 3,5-diaminopyrazole CAN508 inhibits endothelial cell migration and tube formation. In addition, it reduces phosphorylation of the C-terminus of RNA polymerase II and inhibits mRNA synthesis in endothelial cells, in accordance with previous observations that it has high selectivity towards the positive transcriptional regulator P-TEFb. Moreover, CAN508 reduces expression of vascular endothelial growth factor by several human cancer cell lines. The findings suggest that P-TEFb may be an attractive target for anti-angiogenic therapy.


Subject(s)
Azo Compounds/pharmacology , Neovascularization, Pathologic/prevention & control , Positive Transcriptional Elongation Factor B/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , Pyrazoles/pharmacology , Cells, Cultured , Humans , Phosphorylation , RNA Polymerase II/metabolism , RNA, Messenger/genetics , Transcription, Genetic/drug effects
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