新型CDK9小分子抑制剂的设计和发现

目的通过同源模建、计算机虚拟筛选和生物活性筛选,寻找新型的CDK9小分子抑制剂。方法采用同源模建方法得到CDK9的三维晶体构象,用DOCK(分子对接)对小分子三维数据库进行虚拟筛选。采用MTT法对挑选出的化合物进行生物活性测定,然后挑选高活性的化合物进行CDK9与小分子之间相互作用的研究,验证化合物对CDK9激酶活性的抑制作用。结果用DOCK程序对三维化合物库虚拟筛选后挑选出得分高的前1000个化合物,按结构差异化分类,最终选择并购买了27个代表性化合物进行进一步生物学活性测定。27个化合物中12个化合物明显抑制肿瘤细胞的增殖,其中1个化合物C-21的半数抑制浓度(IC50)在20μmol.L-1以下。选择C-21类化合物进一步进行研究,结果显示此化合物能够有效抑制各类肿瘤细胞系的增殖。酶学水平研究表明此类化合物能够有效抑制CDK9激酶活性,并在较低浓度范围内呈明显的剂量依赖关系。结论通过同源模建、计算机虚拟筛选、生物活性实验和分子水平研究,得到了一类靶向CDK9的全新的先导化合物。     

一种新的细胞周期蛋白依赖性激酶(CDK)9抑制剂QHRD107对急性髓系白血病的临床前疗效

QHRD107是细胞周期蛋白依赖性激酶(CDK)9的特异性抑制剂.体外对白血病细胞增殖具有高度抑制作用,在急性髓系白血病异种移植模型体内显著抑制肿瘤细胞生长,并能显著延长小鼠寿命.Molm-13异种移植模型单次灌胃给予QHRD107后,QHRD107迅速被吸收并靶向性分布至肿瘤组织,肿瘤半衰期(T1/2)较血浆延长3倍...     

细胞周期蛋白依赖性激酶9及其抑制剂研究进展

细胞周期蛋白依赖性激酶（CDK）在细胞中不仅负责细胞周期调控,也在细胞转录过程中作为调控因子发挥着重要作用。CDK9作为CDK家族的一员,在细胞转录调控中起重要作用。CDK9和细胞周期蛋白T1结合形成正性转录延长因子b,后者通过磷酸化RNA聚合酶Ⅱ的碳端结构域CTD来调节转录延伸。CDK9抑制剂以竞争性结合的方式,抑制CDK9介导的转录延伸阶段。简要介绍CDK9的功能及其在肿瘤中的作用机制,并总结CDK9抑制剂的研究进展。     

Action of resveratrol alone or in combination with roscovitine, a CDK inhibitor, on cell cycle progression in human HL-60 leukemia cells

Results of a number of epidemiological and experimental studies indicate that polyphenols (e.g. resveratrol (RES), epicatechins etc.), antioxidant agents and abundant micronutrients in our food could have strong anti-mitotic as well as pro-apoptotic effects. In this study we raised the question whether roscovitine (ROSC), an inhibitor of cyclin-dependent kinases (CDKs) with increased selectivity towards CDK2, could be able to affect human leukemia HL-60 cells in which the p53 gene is inactivated and whether ROSC-induced effects could be additionally modulated by compounds of natural origin, especially by polyphenols e.g. RES. Exposure of HL-60 cells to ROSC for 24 h inhibited their proliferation. Flow cytometric analyses revealed that unlike MCF-7 cells, HL-60 cells were arrested in G₁ upon ROSC treatment. Furthermore, ROSC also induced apoptosis in HL-60 cells. After treatment with 40 μM ROSC for 24 h the frequency of hypoploid cells representing cells undergoing apoptosis reached approximately 50%. In the next step the action of RES alone or in combination with ROSC was examined. Interestingly, synergistic effects were observed after combined treatment for 24 h and sequential post-incubation for 48 h in the presence of RES. Such combined treatment resulted in a marked reduction of the frequency of the S- and G₂/M-phase cells and simultaneously increased the G₁ cell population up to 80% at a fourfold lower ROSC dose. Further analyses revealed that the combined treatment strongly activated caspase-3. These results clearly evidence that RES strongly potentiates ROSC-induced apoptosis.     

Effects of the cyclin-dependent kinase inhibitor CYC202 (R-roscovitine) on the physiology of cultured human keratinocytes

CYC202 (R-roscovitine) is a potent cyclin-dependent kinase inhibitor, investigated as a potential anti-cancer agent. The knowledge of the action of this pharmacological agent on normal human cells is still limited. In this study, we have explored the effects of the cyclin-dependent kinase inhibitor CYC202 on normal human epidermal keratinocytes. The loss of cell viability induced by this compound was strongly dependent on the rate of keratinocyte proliferation. At slightly cytotoxic doses, CYC202 inhibited the proliferation of subconfluent keratinocytes in a dose-dependent manner, and at higher concentrations induction of early apoptosis was observed, evidenced by caspase-3 activation. The signal transduction pathways in subconfluent keratinocytes were altered, as CYC202 increased the phosphorylation of p38 MAP kinase. The activation of this kinase was confirmed by the increased phosphorylation of p38 MAPK substrate, the small heat shock protein HSP27. Prolonged inhibition of highly proliferative cells with CYC202 for 48 and 72 h altered the expression of epidermal differentiation markers. The use of the selective p38 kinase inhibitor PD169316 demonstrated that involucrin mRNA was upregulated by CYC202 via p38 MAPK pathway. These effects were strongly dependent on cell density and were observed only in highly proliferative keratinocytes. We concluded that CYC202 although highly potent against cancer cells inhibits also the proliferation and induces early apoptotic events in autocrine culture of normal human keratinocytes, activates p38 MAP kinase pathway and alters the expression of the epidermal differentiation markers. These results suggest that despite this potency against tumour cells, CYC202 must be used attentively in the clinical practice.     

Cyclin-dependent kinase inhibitors: a survey of the recent patent literature

Since the mid-1990s cyclin-dependent kinase (CDK) inhibition has been the subject of an intense drug discovery effort in the pharmaceutical industry and in some academic institutions. Although only few compounds have at present progressed into human clinical trials, the prospect of finding safe agents useful in therapy, particularly in the cancer setting, is still positive. Some trends can be observed that witness the impact of recent findings in CDK basic biological research and technology advancements on the evolution of the patent literature on CDK inhibition. A patent literature review of small organic molecules as CDK inhibitors comprising the years 2001 – 2004 is presented here, as many of the major pharmaceutical companies have shown a continued effort in the field.     

In silico three-dimensional pharmacophores for aiding the discovery of the Pfmrk (Plasmodium cyclin-dependent protein kinases) specific inhibitors for the therapeutic treatment of malaria

The resurgence of malaria and lack of effective antimalarial drugs affect millions of people worldwide every year, causing several million deaths. With the emergence of structure-based drug design methodologies, a major thrust in drug discovery efforts has shifted towards targeting specific proteins in parasites that are involved in their metabolic pathways. Although cyclin-dependent kinases (CDKs), due to their direct role in cell cycle regulations, have been targeted for the development of cancer therapeutics, CDKs for Plasmodium falciparum have only been recently identified to be attractive for the discovery of antimalarials. One of the plasmodium CDK targets is Pfmrk. Being a putative homolog of Cdk7 and, thus, having the possibility of dual functions, both in cell cycle control and gene expression within the parasite, pfrmk has become an interesting antimalarial chemotherapeutic target. This review discusses how in silico methodologies, without the knowledge of the X-ray crystallographic structure of Pfmrk, particularly based on the development of pharmacophores on known inhibitors can aid the discovery and design of Pfmrk-specific inhibitors through virtual screening of compound databases and provides insights into the understanding of the mechanism of binding in the active site of this enzyme.     

A current and comprehensive review of cyclin-dependent kinase inhibitors for the treatment of metastatic breast cancer

Background: Resistance to endocrine treatment generally occurs over time, especially in the metastatic stage. In this paper, we aimed to review the mechanisms of cyclin-dependent kinase (CDK) 4/6 inhibition and clinical usage of new agents in the light of recent literature updates.

Scope: A literature search was carried out using PubMed, Medline and ASCO and ESMO annual-meeting abstracts by using the following search keywords; “palbociclib”, “abemaciclib”, “ribociclib”, “cyclin-dependent kinase inhibitors” and “CDK 4/6” in metastatic breast cancer (MBC). The last search was on 10 June 2017.

Findings: CDKs and cyclins are two molecules that have a key role in cell cycle progression. Today, there are three highly selective CDK4/6 inhibitors in clinical development – palbociclib, ribociclib and abemaciclib. Palbociclib and ribociclib were recently approved by the US FDA in combination with letrozole for the treatment of MBC in a first-line setting, as well as palbociclib in combination with fulvestrant for hormone-receptor (HR)-positive MBC that had progressed while on previous endocrine therapy according to the PALOMA-1, MONALEESA-2 and PALOMA-3 trials, respectively. In the recently published randomized phase III MONARCH 2 trial, abemaciclib plus letrozole had longer progression-free survival and higher objective response rates with less serious adverse events in advanced HR-positive breast cancer previously treated with hormonal treatment.

Conclusion: CDK4/6 inhibition is a new and promising target for patients with hormone-receptor-positive MBC. Both palbociclib and ribociclib showed significant additive benefit for patients receiving first-line treatment for HR-positive, epidermal growth factor receptor-2-negative advanced breast cancer. Palbociclib and abemaciclib also had significant activity in combination with fulvestrant for patients with MBC that progressed on previous endocrine therapy.     

The kinase inhibitor O-cyclohexylmethylguanine (NU2058) potentiates the cytotoxicity of cisplatin by mechanisms that are independent of its effect upon CDK2

O⁶-Cyclohexylmethylguanine (NU2058) was developed as an inhibitor of CDK2 and was previously shown to potentiate cisplatin cytotoxicity in vitro. The aim of this study was to investigate the mechanism of cisplatin potentiation by NU2058.SQ20b, head and neck cancer cells were treated for 2 h with NU2058 (100 μM) and then for a further 2 h with cisplatin and NU2058. NU2058 increased cisplatin cytotoxicity, by clonogenic assay, with a dose modification factor (DMF) of 3.1.NU2058 increased total intracellular platinum levels 1.5-fold, and platinum-DNA adduct levels twofold. Furthermore, the cisplatin-DNA adducts formed were more toxic in the presence of NU2058. To investigate whether the effects of NU2058 on cisplatin adduct levels and toxicity were dependent on CDK2 activity, additional CDK2 inhibitors were tested. NU6230 (CDK2 IC₅₀ 18 μM) was equipotent to NU2058 (CDK2 IC₅₀ 17 μM) as a CDK2 inhibitor in cell-free and cell-based assays, yet did not potentiate cisplatin cytotoxicity. Furthermore, NU6102 was >1000-fold more potent than NU2058 as a CDK2 inhibitor (CDK2 IC₅₀ 5 nM) yet was no more active than NU2058 in potentiating cisplatin.NU2058 also potentiated melphalan (DMF 2.3), and monohydroxymelphalan (1.7), but not temozolomide or ionising radiation. Whilst NU2058 increased melphalan cytotoxicity, it did not increase melphalan-DNA adduct formation.These studies demonstrate that NU2058 alters the transport of cisplatin, causing more Pt-DNA adducts, as well as sensitizing cells to cisplatin- and melphalan-induced DNA damage. However, the effects of NU2058 are independent of CDK2 inhibition.     

Geraniol and beta-ionone inhibit proliferation, cell cycle progression, and cyclin-dependent kinase 2 activity in MCF-7 breast cancer cells independent of effects on HMG-CoA reductase activity

3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase catalyzes the formation of mevalonate, a precursor of cholesterol that is also required for cell proliferation. Mevalonate depletion results in a G1 phase cell cycle arrest that is mediated in part by impaired activity of cyclin-dependent kinase (CDK) 2, and decreased expression of positive regulators of G1 to S phase progression. Inhibition of mevalonate synthesis may, therefore, be a useful strategy to impair the growth of malignant cells. Plant isoprenoids, including beta-ionone and geraniol, have previously been shown to inhibit rodent mammary tumor development, and rodent and avian hepatic HMG-CoA reductase activity. We hypothesized that the putative anti-proliferative and cell cycle inhibitory effects of beta-ionone and geraniol on MCF-7 human breast cancer cells in culture are mediated by mevalonate depletion resulting from inhibition of HMG-CoA reductase activity. Flow cytometric analysis showed a G1 arrest in isoprenoid-treated MCF-7 cells, and also a G2/M arrest at higher concentrations of isoprenoids. These compounds minimally affected the growth of MCF-10F normal breast epithelial cells. Both beta-ionone and geraniol inhibited CDK 2 activity and dose-dependently decreased the expression of cyclins D1, E, and A, and CDK 2 and 4, without changing the expression of p21cip1 or p27kip1. Although both beta-ionone and geraniol also inhibited MCF-7 proliferation, only geraniol inhibited HMG-CoA reductase activity. While these effects were significantly correlated (r2=0.89, P <0.01), they were not causally related, since exogenous mevalonate did not restore growth in geraniol-inhibited cells. These findings indicate that mechanisms other than impaired mevalonate synthesis mediate the anti-proliferative and cell cycle regulatory effects of beta-ionone and geraniol in human breast cancer cells.     

Regulation of MMP-9 gene expression for the development of novel molecular targets against cancer and inflammatory diseases

The need to pharmacologically control the proteolytic activity of matrix metalloproteinases (MMPs) has been commonly acknowledged, despite its limited efficacy in clinical trials. Among the reasons that explain this failure is our limited understanding of the signals that control the expression of MMPs in different cell types during different pathological conditions. Thus, future therapies must rely on more selective approaches. With the continually increasing body of proof implicating MMPs in a large number of diseases, it has become a priority to establish the pertinence of molecules involved in the signalling pathways leading to the expression of these enzymes. MMP-9 is a case in point: its dramatic overexpression in cancer and various inflammatory conditions clearly points to the molecular mechanisms controlling its expression as a potential target for eventual rational therapeutic intervention. In this article, recent progress in the signalling pathways that regulate MMP-9 expression is reviewed, and the latest strategies to be considered in the search for a specific inhibitor of its expression are presented.     

Aurora-A kinase: a novel target both for cellular immunotherapy and molecular target therapy against human leukemia

Background: Although cellular immunotherapy still remains in its infancy, it is one of the important treatment options against cancer. The marked improvement of its clinical efficacy requires a ‘better’ target antigen, which is well recognized by cancer-cell-specific cytotoxic T lymphocytes. We have recently demonstrated the potential of Aurora-A kinase (Aurora-A) as such a ‘better’ target for cellular immunotherapy against human leukemia. Aurora-A is a member of the serine/threonine kinase family that properly regulates the cell division process, and has recently been implicated in tumorigenesis. On the other hand, small-molecule inhibitors targeting Aurora-A have recently been developed and preliminary but promising observations from Phase I clinical trials have been reported. These facts highlight the attractiveness of Aurora-A as an important target of comprehensive cancer therapies. Objective/methods: In this review, we cover Aurora-A in the areas of immunotherapy and small-molecule inhibitor therapy against cancers. Results/conclusions: Aurora-A kinase is an attractive molecule not only as a target for small-molecule inhibitors, but also as a potential target for immunotherapy against cancer.     

Y染色体性别决定区相关高速泳动族框因子9和周期素依赖性激酶4在结直肠息肉、结直肠癌中的表达及意义

目的 探究Y染色体性别决定区相关高速泳动族框因子9(SOX9)和周期素依赖性激酶4(CDK4)在结直肠息肉、结直肠癌中的表达及意义。方法 选取中国人民解放军第八十二集团军医院2015年1月至2017年6月收治的结直肠癌病人病理组织标本(结直肠癌组)94例及癌旁正常结直肠组织(正常结直肠组)39例,另取同时期结直肠息肉病人结直肠息肉组织(结直肠息肉组)51例。采用免疫组织化学SP染色法检测SOX9、CDK4的表达情况,分析SOX9、CDK4表达与结直肠癌病人临床病理参数之间的关系;对结直肠癌病人进行术后复查随访,分析结直肠癌病人生存情况。结果 SOX9在正常结直肠组织、结直肠息肉组织和结直肠癌组织中的阳性表达率分别为10.26%(4/39)、27.45%(14/51)、76.59%(72/94),差异有统计学意义(P<0.05);CDK4在正常结直肠组织、结直肠息肉组织和结直肠癌组织中的阳性表达率分别为7.69%(3/39)、21.57%(11/51)、54.84%(51/94),差异有统计学意义(P<0.05);正常结直肠组织中SOX9、CDK4蛋白表达水平低于结直肠息肉组...     

Induction of G1 phase arrest in MCF human breast cancer cells by pentagalloylglucose through the down-regulation of CDK4 and CDK2 activities and up-regulation of the CDK inhibitors p27(Kip) and p21(Cip)

Pentagalloylglucose (5GG) is a potent and specific inhibitor of NADPH dehydrogenase or xanthine oxidase. In our previous study, we showed that 5GG was able to induce apoptosis in HL-60 cells in a time- and concentration-dependent manner via the activation of caspase-3. Recently, we found that 5GG was capable of perturbing the cell cycle of the human breast cancer cell line MCF-7. DNA flow cytometric analysis showed that 5GG exhibited the ability of blocking MCF-7 cell cycle progression at the G1 phase. The level of several G1 phase-related cyclins and cyclin-dependent kinases did not change in these cells during a 24-hr exposure to 5GG. However, the activity of cyclin E/CDK2 was decreased in a concentration- and time-dependent manner and the activity of cyclin D/CDK4 was inhibited when serum-starved synchronized cells were released from synchronization. p27(Kip) and p21(Cip), inhibitors of cyclin/CDK complexes in G1-phase, were gradually increased after 5GG treatment in a time-dependent manner and the induction of p21(Cip) was correlated with an increase in p53 levels. These results suggest that the suppression of cell-cycle progression in the G1 phase by 5GG was mediated in MCF-7 cells, at least in part, by either the inhibition of cyclin D/CDK4 and cyclin E/CDK2 activity or the induction of the CDK inhibitors p27(Kip) and p21(Cip).     

小檗碱对链脲菌素和高糖高脂饲料诱导糖尿病大鼠骨骼肌CDK9和cyclin T1表达的影响

目的观察小檗碱对2型糖尿病大鼠骨骼肌病理结构改变及CDK9和cyclin T1蛋白表达的影响。方法腹腔注射链脲菌素(35 mg·kg~(-1))加高糖高脂饲料喂养16 wk建立2型糖尿病大鼠模型,随后16 wk每天分别拌食给予低中高剂量小檗碱(75、150、300 mg·kg~(-1))、非诺贝特(100 mg·kg~(-1))和罗格列酮(4 mg·kg~(-1)),用HE染色检查骨骼肌结构病变和免疫组化检测CDK9和cyclin T1的表达。结果骨骼肌纤维在各组大鼠中仍正常分布,中高剂量小檗碱部分地改善糖尿病肌纤维的萎缩;中高剂量小檗碱和罗格列酮都能明显恢复糖尿病大鼠骨骼肌中表达降低的CDK9和cyclin T1至正常水平(P<0.01)。结论小檗碱调控骨骼肌CDK9和cyclin T1蛋白的表达可能是其改善糖尿病骨骼肌纤维萎缩的机制之一。     

采用药效团模型和分子对接方法筛选新型的组蛋白甲基转移酶G9a抑制剂

目的利用药效团模型和分子对接方法对商业化合物库ChemDiv中的G9afocused-libraries进行筛选,希望发现新骨架结构的G9a抑制剂。方法首先,使用Discovery studio 3.1软件分别构建基于配体的药效团模型和基于配体-受体复合物的药效团模型,并根据构建的2个模型再重新定义2个新的药效团模型。然后,构建测试集并测试药效团模型的预测能力。最后,选取最优药效团模型对G9afocused-libraries进行筛选,对筛选出的化合物使用CDOCKER分子对接进行分析与评价。结果测试结果显示,所构建的药效团模型具有一定的预测能力,通过该药效团筛选得到了2个结构新颖的潜在的G9a抑制剂。结论所构建的药效团模型具有一定的可靠性,虚拟筛选发现的G9a抑制剂还需进一步的实验证明。     

丙酮酸激酶缺乏症患儿PKLR基因新发突变分析及文献复习

目的 通过对1例丙酮酸激酶缺乏症(pyruvate kinase deficiency,PKD)患儿的临床症状及其PKLR基因新发突变类型的分析,探讨基因检测对确诊PKD的重要性.方法 报告1例PKD患儿的诊断及新发突变位点,检索国内外报道的PKD患者,汇总并分析PKD临床特征及基因突变类型.结果 该PKD患儿出生后重...