The identification of the essential role of cyclin-dependent kinases (CDKs) in the control of cell division has prompted the development of small-molecule CDK inhibitors as anticancer drugs. For many of these compounds, the precise mechanism of action in individual tumor types remains unclear as they simultaneously target different classes of CDKs - enzymes controlling the cell cycle progression as well as CDKs involved in the regulation of transcription. CDK inhibitors are also capable of activating p53 tumor suppressor in tumor cells retaining wild-type p53 gene by modulating MDM2 levels and activity. In the current study, we link, for the first time, CDK activity to the overexpression of the MDM4 (MDMX) oncogene in cancer cells. Small-molecule drugs targeting the CDK9 kinase, dinaciclib, flavopiridol, roscovitine, AT-7519, SNS-032, and DRB, diminished MDM4 levels and activated p53 in A375 melanoma and MCF7 breast carcinoma cells with only a limited effect on MDM2. These results suggest that MDM4, rather than MDM2, could be the primary transcriptional target of pharmacological CDK inhibitors in the p53 pathway. CDK9 inhibitor atuveciclib downregulated MDM4 and enhanced p53 activity induced by nutlin-3a, an inhibitor of p53-MDM2 interaction, and synergized with nutlin-3a in killing A375 melanoma cells. Furthermore, we found that human pluripotent stem cell lines express significant levels of MDM4, which are also maintained by CDK9 activity. In summary, we show that CDK9 activity is essential for the maintenance of high levels of MDM4 in human cells, and drugs targeting CDK9 might restore p53 tumor suppressor function in malignancies overexpressing MDM4.

• MeSH
• cyklin-dependentní kinasa 9 antagonisté a inhibitory   metabolismus   MeSH
• genetická transkripce MeSH
• imidazoly farmakologie   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• lidé MeSH
• melanom genetika   metabolismus   patologie   MeSH
• MFC-7 buňky MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádory prsu genetika   metabolismus   patologie   MeSH
• piperaziny farmakologie   MeSH
• pluripotentní kmenové buňky metabolismus   MeSH
• proteiny buněčného cyklu biosyntéza   genetika   metabolismus   MeSH
• protoonkogenní proteiny c-mdm2 biosyntéza   genetika   metabolismus   MeSH
• protoonkogenní proteiny biosyntéza   genetika   metabolismus   MeSH
• roskovitin farmakologie   MeSH
• sulfonamidy farmakologie   MeSH
• synergismus léků MeSH
• transfekce MeSH
• triaziny farmakologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• atuveciclib MeSH Prohlížeč
• CDK9 protein, human MeSH Prohlížeč
• Cdk9 protein, mouse MeSH Prohlížeč
• cyklin-dependentní kinasa 9 MeSH
• imidazoly MeSH
• inhibitory proteinkinas MeSH
• MDM2 protein, human MeSH Prohlížeč
• Mdm2 protein, mouse MeSH Prohlížeč
• MDM4 protein, human MeSH Prohlížeč
• Mdm4 protein, mouse MeSH Prohlížeč
• nutlin 3 MeSH Prohlížeč
• piperaziny MeSH
• proteiny buněčného cyklu MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• protoonkogenní proteiny MeSH
• roskovitin MeSH
• sulfonamidy MeSH
• triaziny MeSH

Cyclin-dependent kinase inhibitors (CDKi) have high potential applicability in anticancer therapy, but various aspects of their pharmacokinetics, especially their interactions with drug efflux transporters, have not yet been evaluated in detail. Thus, we investigated interactions of five CDKi (purvalanol A, olomoucine II, roscovitine, flavopiridol and SNS-032) with the ABCB1 transporter. Four of the compounds inhibited efflux of two ABCB1 substrates, Hoechst 33342 and daunorubicin, in MDCKII-ABCB1 cells: Olomoucine II most strongly, followed by roscovitine, purvalanol A, and flavopiridol. SNS-032 inhibited ABCB1-mediated efflux of Hoechst 33342 but not daunorubicin. In addition, purvalanol A, SNS-032 and flavopiridol lowered the stimulated ATPase activity in ABCB1 membrane preparations, while olomoucine II and roscovitine not only inhibited the stimulated ATPase but also significantly activated the basal ABCB1 ATPase, suggesting that these two CDKi are ABCB1 substrates. We further revealed that the strongest ABCB1 inhibitors (purvalanol A, olomoucine II and roscovitine) synergistically potentiate the antiproliferative effect of daunorubicin, a commonly used anticancer drug and ABCB1 substrate, in MDCKII-ABCB1 cells as well as in human carcinoma HCT-8 and HepG2 cells. We suggest that this pronounced synergism is at least partly caused by (i) CDKi-mediated inhibition of ABCB1 transporter leading to increased intracellular retention of daunorubicin and (ii) native cytotoxic activity of the CDKi. Our results indicate that co-administration of the tested CDKi with anticancer drugs that are ABCB1 substrates may allow significant dose reduction in the treatment of ABCB1-expressing tumors.

• MeSH
• adenosintrifosfatasy metabolismus   MeSH
• buněčná membrána účinky léků   metabolismus   MeSH
• buněčné linie MeSH
• cyklin-dependentní kinasy antagonisté a inhibitory   MeSH
• daunomycin farmakologie   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• P-glykoproteiny antagonisté a inhibitory   genetika   MeSH
• proliferace buněk účinky léků   MeSH
• protinádorové látky farmakologie   MeSH
• puriny farmakologie   MeSH
• regulace genové exprese účinky léků   MeSH
• roskovitin MeSH
• synergismus léků MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 6-((3-chloro)anilino)-2-(isopropyl-2-hydroxyethylamino)-9-isopropylpurine MeSH Prohlížeč
• ABCB1 protein, human MeSH Prohlížeč
• adenosintrifosfatasy MeSH
• cyklin-dependentní kinasy MeSH
• daunomycin MeSH
• inhibitory proteinkinas MeSH
• messenger RNA MeSH
• olomoucine II MeSH Prohlížeč
• P-glykoproteiny MeSH
• protinádorové látky MeSH
• puriny MeSH
• roskovitin MeSH

Purine cyclin-dependent kinase inhibitors have been recognized as promising candidates for the treatment of various cancers; nevertheless, data regarding interaction of these substances with drug efflux transporters is still lacking. Recently, we have demonstrated inhibition of breast cancer resistance protein (ABCG2) by olomoucine II and purvalanol A and shown that these compounds are able to synergistically potentiate the antiproliferative effect of mitoxantrone, an ABCG2 substrate. In this follow up study, we investigated whether olomoucine II and purvalanol A are transported by ABCG2 and ABCB1 (P-glycoprotein). Using monolayers of MDCKII cells stably expressing human ABCB1 or ABCG2, we demonstrated that olomoucine II, but not purvalanol A, is a dual substrate of both ABCG2 and ABCB1. We, therefore, assume that pharmacokinetics of olomoucine II will be affected by both ABCB1 and ABCG2 transport proteins, which might potentially result in limited accumulation of the compound in tumor tissues or lead to drug-drug interactions. Pharmacokinetic behavior of purvalanol A, on the other hand, does not seem to be affected by either ABCG2 or ABCB1, theoretically favoring this drug in the potential treatment of efflux transporter-based multidrug resistant tumors. In addition, we observed intensive sulfatation of olomoucine II in MDCKII cell lines with subsequent active efflux of the metabolite out of the cells. Therefore, care should be taken when performing pharmacokinetic studies in MDCKII cells, especially if radiolabeled substrates are used; the generated sulfated conjugate may largely contaminate pharmacokinetic analysis and result in misleading interpretation. With regard to chemical structures of olomoucine II and purvalanol A, our data emphasize that even drugs with remarkable structure similarity may show different pharmacokinetic behavior such as interactions with ABC transporters or biotransformation enzymes.

• MeSH
• ABC transportér z rodiny G, člen 2 MeSH
• ABC transportéry metabolismus   MeSH
• biologický transport MeSH
• buněčné linie MeSH
• chemorezistence účinky léků   MeSH
• nádorové proteiny metabolismus   MeSH
• P-glykoprotein metabolismus   MeSH
• P-glykoproteiny MeSH
• psi MeSH
• puriny farmakokinetika   MeSH
• zvířata MeSH
• Check Tag
• psi MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 6-((3-chloro)anilino)-2-(isopropyl-2-hydroxyethylamino)-9-isopropylpurine MeSH Prohlížeč
• ABC transportér z rodiny G, člen 2 MeSH
• ABC transportéry MeSH
• ABCB1 protein, human MeSH Prohlížeč
• ABCG2 protein, human MeSH Prohlížeč
• nádorové proteiny MeSH
• olomoucine II MeSH Prohlížeč
• P-glykoprotein MeSH
• P-glykoproteiny MeSH
• puriny MeSH

Deregulation of cyclin-dependent kinases (CDKs) has been associated with many cancer types and has evoked an interest in chemical inhibitors with possible therapeutic benefit. While most known inhibitors display broad selectivity towards multiple CDKs, recent work highlights CDK9 as the critical target responsible for the anticancer activity of clinically evaluated drugs. In this review, we discuss recent findings provided by structural biologists that may allow further development of highly specific inhibitors of CDK9 towards applications in cancer therapy. We also highlight the role of CDK9 in inflammatory processes and diseases.

• MeSH
• cyklin-dependentní kinasa 9 antagonisté a inhibitory   metabolismus   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• lékové transportní systémy * MeSH
• lidé MeSH
• nádory farmakoterapie   enzymologie   MeSH
• protinádorové látky farmakologie   MeSH
• racionální návrh léčiv MeSH
• zánět enzymologie   patologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• cyklin-dependentní kinasa 9 MeSH
• inhibitory proteinkinas MeSH
• protinádorové látky MeSH