Cell cycle regulation and anticancer drug discovery

Cellular growth,development,and differentiation are tightly controlled by a conserved biological mechanism:the cell cycle.This cycle is primarily regulated by cyclin-dependent kinase(CDK)-cyclin complexes,checkpoint kinases,and CDK inhibitors.Deregulation of the cell cycle is a hallmark of the transformation of normal cells into tumor cells.Given its importance in tumorigenesis,several cell cycle inhibitors have emerged as potential therapeutic drugs for the treatment of cancers-both as singleagent therapy and in combination with traditional cytotoxic or molecular targeting agents.In this review,we discuss the mechanisms underlying cell cycle regulation and present small-molecule anticancer drugs that are under development,including both pan-CDK inhibitors and CDK4/6-selective inhibitors.In addition,we provide an outline of some promising CDK inhibitors currently in preclinical and clinical trials that target cell cycle abnormalities in various cancers.

Viral infections and cell cycle G2/M regulation

Progression of cells from G2 phase of the cell cycle to mitosis is a tightly regulated cellular process that requires activation of the Cdc2 kinase, which determines onset of mitosis in all eukaryotic cells. In both human and fission yeast (Schizosaccharomyces pombe) cells, the activity of Cdc2 is regulated in part by the phosphorylation status of tyrosine 15 (Tyr15) on Cdc2, which is phosphorylated by Wee1 kinase during late G2 and is rapidly dephosphorylated by the Cdc25 tyrosine phosphatase to trigger entry into mitosis. These Cdc2 regulators are the downstream targets of two well- characterized G2/M checkpoint pathways which prevent cells from entering mitosis when cellular DNA is damaged or when DNA replication is inhibited. Increasing evidence suggests that Cdc2 is also commonly targeted by viral proteins, which modulate host cell cycle machinery to benefit viral survival or replication. In this review, we describe the effect of viral protein R (Vpr) encoded by human immunodeficiency virus type 1 (HIV-1) on cell cycle G2/M regulation. Based on our current knowledge about this viral effect, we hypothesize that Vpr induces cell cycle G2 arrest through a mechanism that is to some extent different from the classic G2/M checkpoints. One the unique features distinguishing Vpr-induced G2 arrest from the classic checkpoints is the role of phosphatase 2A (PP2A) in Vpr-induced G2 arrest. Interestingly, PP2A is targeted by a number of other viral proteins including SV40 small T antigen, polyomavirus T antigen, HTLV Tax and adenovirus E4orf4. Thus an in-depth understanding of the molecular mechanisms underlying Vpr-induced G2 arrest will provide additional insights into the basic biology of cell cycle G2/M regulation and into the biological significance of this effect during host-pathogen interactions.

The effect of celastrol in combination with 5-fluorouracil on proliferation and apoptosis of gastric cancer cell lines

Background:Despite the availability of chemotherapy drugs such as 5-fluorouracil(5-FU),the treatment of some cancers such as gastric cancer remains challenging due to drug resistance and side effects.This study aimed to investigate the effect of celastrol in combination with the chemotherapy drug 5-FU on proliferation and induction of apoptosis in human gastric cancer cell lines(AGS and EPG85-257).Materials and Methods:In this in vitro study,AGS and EPG85-257 cells were treated with different concentrations of celastrol,5-FU,and their combination.Cell proliferation was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)assay.The synergistic effect of 5-FU and celastrol was studied using Compusyn software.The DNA content at different phases of the cell cycle and apoptosis rate was measured usingflow cytometry.Results:Co-treatment with low concentrations(10%inhibitory concentration(IC10))of celastrol and 5-FU significantly reduced IC50(p<0.05)so that 48 h after treatment,IC50 was calculated at 3.77 and 6.9μM for celastrol,20.7 and 11.6μM for 5-FU,and 5.03 and 4.57μM for their combination for AGS and EPG85-257 cells,respectively.The mean percentage of apoptosis for AGS cells treated with celastrol,5-FU,and their combination was obtained 23.9,41.2,and 61.9,and for EPG85-257 cells 5.65,46.9,and 55.7,respectively.In addition,the 5-FU and celastrol-5-FU combination induced cell cycle arrest in the synthesis phase.Conclusions:Although celastrol could decrease the concentration of 5-fluorouracil that sufficed to suppress gastric cancer cells,additional studies are required to arrive at conclusive evidence on the anticancer effects of celastrol.

Effects of virus infection on expression of cell cycle regulatory proteins in the unicellular marine algae Emiliania huxleyi

The authors have investigated the biochemical events by which marine algal virus infection induces cell cycle arrest. The key G 2 /M-phase regulatory proteins are analyzed by immunobloting in unicel-lular Emiliania huxleyi,suggesting that virus induced cell cycle arrest is related with virus＇s effect on cyclins and cyclin dependent kinases. E. huxleyi virus（EhV） represses Cdc2/cyclinB complex activity by inhibiting the activity of Cdc2 kinase in a phosphorylation-related manner,blocking host cells G 2 /M checkpoint. Dephosphorylated /inactive Cdc25C combined with up-regulation of Wee1 expression at early infect period appears to be important mechanisms by which EhV represses Cdc2/cyclinB complex activity that is required for entry into M phase. This study has allowed us to confirm that algal virus infection leads to selective activation or inhibition of certain cell-cycle factors,which may play a significant role in establishing a more efficient environment for viral gene expression and DNA replication.

Research Progress in the Regulation of Tumor Cells and Tumor Stem Cells at Multiple Targets by Antrodia camphorata

Extensive in vitro and in vivo research reveals multiple intracellular molecular targets of Antrodia camphorata,and these targets affect growth,apoptosis,angiogenesis,invasion and metastasis of cells.These targets include tumor suppressor,cell cycle regulator,transcription factor,angiogenesis and metastasis factor,apoptosis and survival regulator,etc.Additionally,more and more attention has been paid to the molecular mechanism of A.camphorata on the regulation of tumor stem cells.Meanwhile,there is evidence that the immunoregulation of A.camphorata is enhanced,which may lead cell cycle arrest or apoptosis.In this paper,molecular mechanism of tumor cells and tumor stem cells regulated at multiple targets by A.camphorata in vitro and in vivo in the past decade is summarized.

The Impact Heme Oxygenase -1 on the Regulating Factors of Hepatoma Cells＇ Cell Cycle

It aims to analyze the impact heme oxygenase -1 （heme oxygenase 1, HO-1） on regulating factors of human hepatoma cell HepG2＇s cell cycle, through constructing recombinant vector of pcDNA3.1 containing wild-type and mutant HO-1 gene （＋）-wtHO-1 and pcDNA3.1 （＋）-mHO-1G143H. By using the method of liposome-mediated, the recombinant vector was transfected hepatoma cell line HepG2. And the transfected one with empty vector was treated as a control group. By the selection of G418, stable expression of wild-type and mutant HO-1 in HepG2 liver cancer cell lines were established. Use the blot of semi-quantitative RT-PCR and Western to test transfected cell lines expressing levels of riO-1 mRNA and protein. As HO-1 expression in stably transfected cell lines altered, we use Western blot to test transfected cell lines P21, P27 protein expression levels. As result shows, we got 1 HO-over-expression of wild-type and mutant in HepG2 cells; wild- type and mutant＇s over expression of HO-1 can induce the expression of tumor suppressor genes p21 and p27.we got the conclusion that HO-l＇s over-expression of tumor suppressor genes p21 and p27 is unrelated to the expression of heme decomposition products. HO-1 may regulate the expression of p21 and p27 through other mechanisms.

The expression and significance of cyclin B1 and survivin in human non-small cell lung cancer

Objective:We studied the expression of cyclin B1 and survivin in human non-small cell lung cancer(NSCLC),and the relationship between such expression and clinicopathological features of NSCLC.Methods:One hundred cases of tissue specimen including NSCLC,neighboring noncancerous tissue and normal lung tissue were collected at random.These specimens were detected by immunohistochemical methods.Results:The expression of cyclin B1 and survivin showed significant difference(P < 0.01) between NSCLC tissues,proliferating epithelial cells of bronchioles and small bronchi in neighboring noncancerous tissues,and normal lung tissues.Compared with normal lung tissues,there was an overexpression of cyclin B1 and survivin in NSCLC and an enhancing expression of cyclin B1 and survivin in proliferating epithelial cells of bronchioles and small bronchi in neighboring noncancerous tissues.Significantly positive correlation was found between the overexpression of cyclin B1 and that of survivin in 100 NSCLC cases(P < 0.01).The significantly positive correlation was also found between the enhancing expression of cyclin B1 and that of survivin in proliferating epithelial cells of bronchioles and small bronchi in neighboring noncancerous tissues(P < 0.01).No statistical significance was found between the different histological types,the differentiated degree,lymphatic metastasis and the expression of cyclin B1 and survivin(P > 0.05) in NSCLC.Statistical significance was marked between different clinical stages of NSCLC and the expression of cyclin B1 and survivin(P < 0.05).Conclusion:The overexpression of cyclin B1 and survivin was found in NSCLC.The expression of cyclin B1 and survivin might be up-regulated during an early step of tumorigenesis and during the development of NSCLC.The progression of cell cycle could be efficiently connected with the control of apoptosis by the interrelations between the overexpression of cyclin B1 and that of survivin in NSCLC during the G2/M phase.The overexpression of cyclin B1 and survivin might be used as marker in showing the dividing and proliferating ability,and the inhibiting apoptosis ability(lengthening cell lifespan) of NSCLC.Moreover,the overexpression of cyclin B1 and survivin was associated with the clinic stages of NSCLC.

Polo-like kinase 1,on the rise from cell cycle regulation to prostate cancer development

Polo-like kinase 1(Plk1),a well-characterized member of serine/threonine kinases Plk family,has been shown to play pivotal roles in mitosis and cytokinesis in eu-karyotic cells.Recent studies suggest that Plk1 not only controls the process of mitosis and cytokinesis,but also,going beyond those previously described functions,plays critical roles in DNA replication and Pten null prostate cancer initiation.In this review,we briefly summarize the functions of Plk1 in mitosis and cytokinesis,and then mainly focus on newly discov-ered functions of Plk1 in DNA replication and in Pten-null prostate cancer initiation.Furthermore,we briefly introduce the architectures of human and mouse pros-tate glands and the possible roles of Plk1 in human prostate cancer development.And finally,the newly chemotherapeutic development of small-molecule Plk1 inhibitors to target Plk1 in cancer treatment and their translational studies are also briefly reviewed.

Identification of a seven-gene signature and establishment of a prognostic nomogram predicting overall survival of triple-negative breast

Background: Triple-negative breast cancer (TNBC) is a highly heterogeneous breast cancersubtype characterized by the absence of expression of estrogen receptor (ER), progesteronereceptor (PR), and human epidermal growth factor receptor 2 (HER2). TNBC exhibitsresistance to hormone and HER2-targeted therapy, along with a higher incidence ofrecurrence and poorer prognosis. Therefore, exploring the molecular features of TNBC andconstructing prognostic models are of significant importance for personalized treatmentstrategies. Methods: In this research, bioinformatics approaches were utilized to screendifferentially expressed genes in 405 TNBC cases and 128 normal tissue samples from 8 GEOdatasets. Key core genes and signaling pathways were further identified. Additionally, aprognostic model incorporating seven genes was established using clinical and pathologicalinformation from 169 TNBC cases in the TCGA dataset, and its predictive performance wasevaluated. Results: Functional analysis revealed dysregulated biological processes such asDNA replication, cell cycle, and mitotic chromosome separation in TNBC. Protein-proteininteraction network analysis identified ten core genes, including BUB1, BUB1B, CDK1,CDC20, CDCA8, CCNB1, CCNB2, KIF2C, NDC80, and CENPF. A prognostic model consistingof seven genes (EXO1, SHCBP1, ABRACL, DMD, THRB, DCDC2, and APOD) was establishedusing a step-wise Cox regression analysis. The model demonstrated good predictiveperformance in distinguishing patients' risk. Conclusion: This research provides importantinsights into the molecular characteristics of TNBC and establishes a reliable prognosticmodel for understanding its pathogenesis and predicting prognosis. These findingscontribute to the advancement of personalized treatment for TNBC.

Identification of osteopontin as the most consistently over-expressed gene in intrahepatic cholangiocarcinoma: Detection by oligonucleotide microarray and real-time PCR analysis

AIM: To investigate the molecular pathways involved in human cholangiocarcinogenesis by gene expression profiling. METHODS: Oligonucleotide arrays (Affymetrix U133A) were used to establish a specific gene expression profile of intrahepatic CCC in comparison to corresponding non- malignant liver tissue. To validate the expression values of the most overexpressed genes, RT-PCR experiments were performed. RESULTS: Five hundred and fifty-two statistically differentially expressed genes/ESTs (221 probes significantly up-regulated, 331 probes down-regulated; P < 0.05; fold change > 2; ≥ 70%) were identified. Using these data and two-dimensional cluster analysis,a specific gene expression profile was obtained allowing fast and reproducible differentiation of CCC, which was confirmed by supervised neuronal network modelling. The most consistently overexpressed gene (median fold change 33.5, significantly overexpressed in 100%) encoded osteopontin. Furthermore, an association of various genes with the histopathological grading could be demonstrated. CONCLUSION: A highly specific gene expression profile for intrahepatic CCC was identified, allowing for its fast and reproducible discrimination against non- malignant liver tissue and other liver masses. The most overexpressed gene in intrahepatic CCC was the gene encoding osteopontin. These data may lead to a better understanding of human cholangiocarcinogenesis.

Co-delivery of chemotherapeutic drugs and cell cycle regulatory agents using nanocarriers for cancer therapy

Combination chemotherapy is widely exploited to overcome multidrug resistance(MDR) and enhance the therapeutic effect of anti-tumor agents clinically. The traditional combination regimens applied in clinical practice still suffer from various obstacles, such as inevitable side effects.Fortunately, the application of nanotechnology and the proposal of co-delivery systems make the combination therapy more effective. The occurrence, development, and metastasis of tumors are closely related to the cell cycle. The sensitivity of tumor cells to chemotherapeutic drugs can be improved with the cooperation of cell cycle regulators. In this review, the influence of the cell cycle on tumorigenesis and development is introduced briefly. The current strategies of combining chemotherapeutic drugs and cell cycle regulators through codelivery systems are discussed in detail. We also sketch the possibility of treating tumors mildly via artificially controlling the cell cycle and outline the challenges and perspectives about the improvement of co-delivery systems for cancer therapy.

The Nucleolus and Viral Infection

The nucleolus is a subnuclear structure of eukaryocytes. It was thought that nucleolus only participates in the biogenesis and processing of rRNA. However, more and more evidence shows that it has many other functions, such as tRNA precursor processing, stress sensing and it is also involved in gene silencing, senescence and cell cycle regulation. Here, we summarize the recent understandings about the nucleolar functions, the regulation of nucleolar localization of proteins and the role that the nucleolus plays in virus infection, in which some related studies of Herpes simplex virus type 1 (HSV-1) US11, UL24 and bovine herpesvirus-1 infected cell protein 27 (BICP27) carried out in our lab will also be included.

THE EXPRESSION OF p16 AND CYCLIN D_1 IN PROLIFERATIVE ENDOMETRIUM AND ENDOMETRIAL CARCINOMA

Objective To study the role of p16 and cyclin D 1 in the genesis and development of endometrial carcinoma.Methods 12 cases of normal endometrium,22 cases of proliferative endometrium and 41 cases of endometrial carcinoma were detected for the expression of p16 and cyclin D 1 by means of immunohistochemical S P. Results In normal endometrium p16 was expressed while cyclin D 1 was almost negative in the proliferative phase,but both of them were negative in the secretory phase.Among the groups of the simple and compound hyperplasia, the atypical hyperplasia and the endometrial carcinoma,the expression of p16 showed a descending tendency, while the expression of cyclin D 1 showed an ascending tendency.In endometrial carcinomas the expression of p16 was significantly lower than that of normal endometrium and proliferative endometrium( P <0.01, P <0.05).However, the expression of cyclin D 1 in proliferate endometrium and endometrial carcinoma was significantly higher than that in normal endometrium ( P<0.05,P<0.01) .The overexpression of cyclin D 1 in the atypical hyperplasia group was obviously different from that in the simple and compound hyperplasia group ( P <0.01).In endometrial carcinoma,the expression of p16 was decreasing with the descending of cell differentiate degree, on the opposite, the expression of cyclin D 1 was increased and there existed a negative correlation between them.It was also observed that the overexpression of cyclin D 1 was significant different between G 1 and G 2,G 3(P<0.01).Conclusion p16 is a negative regulating factor of cell cycle in endometrial carcinoma, while cyclin D 1 is a positive one.Both of them are important in the genesis and development of endometrial carcinoma.The low expression of p16 and the overexpression of cyclin D 1 are related with the malicious biological behaviors of endometrial carcinoma and maybe play an important role in the judgement of prognosis.Overexpression of cyclin D 1 may be an earlier molecular event in the genesis of endometrial carcinoma.

Effect of Aspirin on DMBA-induced mammary gland carcinogenesis and its anti-tumor mechanism in MCF-7 breast cancer cell

The effects of Aspirin on tumor chemoprevention and inhibition have been debated and researched in recent years and its effects on colorectal cancer are quite clear.For breast cancer,however,conclusions are inconsistent and the anti-tumor mechanism of Aspirin is not clear yet.In our study,we used DMBA-induced mammary gland carcinogenesis model to assess the chemoprevention effect of Aspirin on mammary precancerous lesions.After SD rats were treated with Aspirin,the total numbers of precancerous lesion in experimental groups were 16（40 mg/kg Aspirin） and 13（20 mg/kg Aspirin）,while the number in control group was 35.In vitro,we found that Aspirin inhibited cell proliferation in human breast cancer cell line MCF-7 by SRB assay with no apparent cytotoxity under the doses of 10,8,6,4 and 2 mM,the inhibitory rates were 86.96%,54.56%,24.83%,14.24% and 4.49%,respectively.In mechanism research,the results of gene microarray assay demonstrated that 4 mM and 2 mM Aspirin were effective in changing gene expression profile in MCF-7 cells.The expression of cell cycle regulator,cyclin A,was significantly down-regulated under the same doses,while the down-regulation of Cdk2 was only remarkable at 4 mM.Our findings reveal that Aspirin is effective in tumor inhibition during initial phase in rats.In MCF-7 cells,Aspirin reduces cell proliferation without significant cytotoxity and its possible mechanism involves altering tumor-related gene expression and regulating cell cycle process.

AURKB and MAPK involvement in the regulation of the early stages of mouse zygote development

Aurora kinases have become a hot topic for research as they have been found to play an important role in various stages of mitotic cell division and to participate in malignant conversions of tumors. The participation of Aurora kinases in the regulation of oocyte meiosis has been recently reported, but their participation in mammalian early embryonic development remained unclear. The object of our study was to establish the spatio-temporal expression pattern of Aurora kinase B (AURKB) in mouse zygotes during the first cleavage, to reveal its functions in the early development of mouse zygotes, and to define the involvement of AURKB in mitogen-activated protein kinase (MAPK) signaling. Our results showed that in mouse zygotes AURKB expression increased in G1 phase and peaked in M phase. AURKB protein distribution was found to be in association with nuclei and distributed throughout the cytoplasm in a cell cycle-dependent manner. Functional disruption of AURKB resulted in abnormal division phenotypes or mitotic impairments. U0126, a specific mitogen-activated protein kinase kinase (MEK) inhibitor, caused significantly altered morphologies of early embryos together with a decrease in protein expression and kinase activity of AURKB. Our results indicated that the activity of AURKB was required for regulating multiple stages of mitotic progression in the early development of mouse zygotes and was correlated with the activation of the MAPK pathway.

Scaffold protein MAPK8IP2 expression is a robust prognostic factor in prostate cancer associated with AR signaling activity

Mitogen-activated protein kinase-8-interacting protein 2(MAPK8IP2)is a scaffold protein that modulates MAPK signal cascades.Although MAPK pathways were heavily implicated in prostate cancer progression,the regulation of MAPK8IP2 expression in prostate cancer is not yet reported.We assessed MAPK8IP2 gene expression in prostate cancer related to disease progression and patient survival outcomes.MAPK8IP2 expression was analyzed using multiple genome-wide gene expression datasets derived from The Cancer Genome Atlas(TCGA)RNA-sequence project and complementary DNA(cDNA)microarrays.Multivariable Cox regressions and log-rank tests were used to analyze the overall survival outcome and progression-free interval.MAPK8IP2 protein expression was evaluated using the immunohistochemistry approach.The quantitative PCR and Western blot methods analyzed androgen-stimulated MAPK8IP2 expression in LNCaP cells.In primary prostate cancer tissues,MAPK8IP2 mRNA expression levels were significantly higher than those in the case-matched benign prostatic tissues.Increased MAPK8IP2 expression was strongly correlated with late tumor stages,lymph node invasion,residual tumors after surgery,higher Gleason scores,and preoperational serum prostate-specific antigen(PSA)levels.MAPK8IP2 upregulation was significantly associated with worse overall survival outcomes and progression-free intervals.In castration-resistant prostate cancers,MAPK8IP2 expression strongly correlated with androgen receptor(AR)signaling activity.In cell culture-based experiments,MAPK8IP2 expression was stimulated by androgens in AR-positive prostate cancer cells.However,MAPK8IP2 expression was blocked by AR antagonists only in androgen-sensitive LNCaP but not castration-resistant C4-2B and 22RV1 cells.These results indicate that MAPK8IP2 is a robust prognostic factor and therapeutic biomarker for prostate cancer.The potential role of MAPK8IP2 in the castration-resistant progression is under further investigation.

Targeting BCL2 pathways in CLL: a story of resistance and ingenuity

Chronic lymphocytic leukemia(CLL)is common amongst leukemic malignancies,prompting dedicated investigation throughout the years.Over the last decade,the treatment for CLL has significantly advanced with agents targeting B-cell lymphoma 2(BCL2),Bruton's tyrosine kinase,and CD20.Single agents or combinations of these targets have proven efficacy.Unfortunately,resistance to one or multiple of the new treatment targets develops.Our review investigates various mechanisms of resistance to BCL2 inhibitors,including mutations in BCL2,alterations in the Bcl protein pathway,epigenetic modifications,genetic heterogeneity,Richter transformation,and alterations in oxidative phosphorylation.Additionally,the review will discuss potential avenues to overcome this resistance with novel agents such as bispecific antibodies,Bruton's tyrosine kinase(BTK)degraders,non-covalent BTK inhibitors,and chimeric antigen receptor T(CART).

Spatio-Temporal Expression Patterns of Aurora Kinases A, B in Mouse Zygotes during the First Mitosis

Objective To investigate the expression and localization of Aurora kinase A （A URKA ） and Aurora kinase B （A URKB） in mouse zygotes during the process of the first mitosis. Methods Quantitative real-time RT-PCR and Western blotting were performed to analyze the expression of AURKA and AURKB. The subcellular location of AURKA and A URKB was studied by confocal microscopy. Results A URKA and A URKB were increasingly expressed from phase G1 and peaked at phase M. After the entrance into mitosis A URKB became the predominant form both in mRNA and protein levels. The proteins of A URKA and A URKB both distributed in the cytoplasm and were associated with nucleus during the first mitosis of mouse zygotes, with some details in different. Conclusion The expression and localization of Aurora kinases A and B was in a cell- cycle regulated manner during the process of the cleavage of mouse zygotes. This discovery will aid in future investigations on their specific roles and molecular mecha- nisms in the regulation of mammalian early embryonic development.

Centrosome Defects in Hematological Malignancies: Molecular Mechanisms and Therapeutic Insights

Defects in centrosomes are associated with a broad spectrum of hematological malignancies,such as leukemia and lymphoma.Centrosomes in these malignancies display both numerical and structural aberrations,including alterations in the number and size of centrioles,inappropriate post-translational modification of centrosomal proteins,and extra centrosome clustering.There is accumulating evidence that centrosome defects observed in hematological malignancies result from multiple factors,including dysregulation of the centrosome cycle and impairment of centriole biogenesis.In this review,we discuss the plausible mechanisms of centrosome defects and highlight their consequences in hematological malignancies.We also illustrate the latest therapeutic strategies against hematological malignancies by targeting centrosome anomalies.

Design, Synthesis and Preliminary Biological Evaluation of Purine-2,6-diamine Derivatives as Cyclin-dependent Kinase （CDK） Inhibitors

Novel purine-2,6-diamine derivatives were designed and synthesized as cyclin-dependent kinase （CDK） inhibi- tors. According to the preliminary biological evaluation, most of the compounds show good inhibitory activities in CDK1 enzyme assay and potent antiproliferative activities in some tumor cell lines. Especially, compound lla （IC50=0.35 μmol/L for CDK1/cyclin B and IC50： effect compared with Roscovitine （IC50= 2.54 CDK2/cyclin A）. 0.023 μmol/L for CDK2/cyclin A） possessed better inhibitory μmol/L for CDK1/cyclin B and IC50=0.092 μ mol/L for