Effects of estradiol on cell cycle and cyclin proteins of vascular smooth muscle cells in rats

To study the effects of 17β-estradiol(E2) on the growth of cultured rat vascular smooth muscle cells (VSMC).Methods The cell cycle and the expressions of Cyclin D1 and CDK4 proteins were examined by flow cytometry in VSMC cultured in different concentrations (0～100 nmol/L) of 17β-estradiol with or without serum.Results Under serum-stimulating conditions,17β-estradiol(1,10,100 nmol/L) promoted VSMC proliferation by accelerating their cell cycle progression from G1 to S phases,and the cell rates at S were (31.89±9.14)%(35.90±4.59)% and (30.77±1.20)% respectively,significantly higher than the corresponding values of control cells (21.63±1.80)%.This was accompanied by the significantly increased expression of Cyclin D1 and CDK4 proteins.In the cultures without serum,however,high concentrations (10,100 nmol/L) of E2 induced a cell cycle arrest at G1 phase,which was characterizsed by decreased cell rates at S phase [(9.93±1.43)% and (8.76±1.80)% respectively,P<0.05] as compared with the corresponding control values and a down-regulation of expressions of Cyclin D1 and CDK4 proteins.Conclusion E2 can either promote or inhibit VSMC proliferation depending upon the presence or absence of serum mitogens.The underlying mechanism may be associated with the hormone’s action on the expression of Cyclin D1 and CDK4 which act as the G1 phase regulators.4 refs.

The Experimental and Clinical Study on the Effect of Curcumin on Cell Cycle Proteins and Regulating Proteins of Apoptosis in Acute Myelogenous Leukemia

To investigate whether the Bcl- 2 gene family is involved in m odulating mechanism of apoptosis and change of cell cycle protein induced by curcumin in acute myeloid leukemia HL - 6 0 cell line and primary acute m yelogenous leukem ic cells,the Bcl- 2 family member Mcl- 1,Bax and Bak and cell cycle proteins including P2 7kipl,P2 1wafl,cyclin D3and p Rbp- were selected and their ex- pression detected by SABC imm uno- histochem ical stain m ethod.The attitude of sub- G1 peak in DNA histogram was determined by FCM.The TU NEL positive cell percentage was identified by term inal deoxynucleotidyl transferase (Td T ) - m ediated Biotin d U NP end labeling technique.It was found that when HL - 6 0 cells were treated with 2 5μm ol/ L curcumin for 2 4 h,the expression level of Mcl- 1was down- regulated,but that of Bax and Bak up- regulated time- dependently.There was significant difference in the expression level of Mcl- 1,Bax and Bak between the curcumin- treated groups and control group(P<0 .0 5 - 0 .0 1) .At the sam e time,curcumin had no effect on progress of cell cycle in prim aty acute m yelogenous leukemia at newly diagnosis,but could in- crease the peak of Sub- G1 (P<0 .0 5 ) ,and down- regulate the expression of Mcl- 1and up- regulate the expression of Bax and Bak with the difference being statistically significant.The expression of P2 7kipl,P2 1wafl and p Rbp- were elevated and thatof cyclin D3decreased in the presence of curcum in. These findings suggested thatthe Bcl- 2 gene fam ily indeed participated in the regulatory process of apoptosis induced by curcumin in HL - 6 0 cells and AML cells.Curcumin can induce apoptosis of primary acute myelogenous leukemic cells and disturb cell cycle progression of HL - 6 0 cells.The m echanism appeared to be m ediated by perturbing G0 / G1 phases checkpoints which associated with up- regulation of P2 7kipl,P2 1wafl and p Rbp- expression,and down- regulation of cyclin D3.

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.

Inhibitory Effects of NO-Fluvastatin on Proliferation of Human Lens Epithelial Cells in vitro by Modulating Cell Cycle Regulatory Proteins

The effects of NO-Fluvastatin on proliferation of human lens epithelial cells （HLECs） and the action mechanism were investigated. Cell proliferation was assessed by MTT assay. Cell cycle was analyzed by flow cytometry. The expression of cell cycle regulatory proteins CyclinE mRNA and P21waf1 mRNA was detected by reverse transcription polymerase chain reaction （RT-PCR）. MTT staining colorimetry showed that HLECs proliferation was markedly inhibited by NO-Fluvastatin and the effect was dependently related to time （24, 48 and 72 h） and dosage （1, 5 and 20 μmol/L）. Flow cytometry revealed that NO-Fluvastatin could significantly block HLECs in the G0/G1 phase, resulting in the increased cells in the G0/G1 phase and decreased in the S phase （P〈0.05）. RT-PCR showed that NO-Fluvastatin could obviously inhibit the CyclinE mRNA expression and induce the P21waf1 mRNA expression as compared with the negative control groups （P〈0.05）. This experiment suggested that NO-Fluvastatin could suppress the proliferation of HLECs by regulating cell cycle regulatory proteins （inhibiting the expression of CyclinE mRNA and inducing the expression of P21waf1 mRNA）, resulting in the arrest of HLECs in the G0/G1 phase, which can offer theory basis for NO-Fluvastatin in treating posterior capsular opacification in clinic practice.

NCAPD2 serves as a potential prognostic biomarker for lung adenocarcinoma and promotes cell proliferation,migration,invasion and cell cycle in vitro

Objectives:The pro-oncogenic effects of NCAPD2 have been extensively studied across various tumor types;however,its precise role within the context of lung adenocarcinoma(LUAD)remains elusive.This study aims to elucidate the biological functions of NCAPD2 in LUAD and unravel the underlying mechanistic pathways.Methods:Utilizing bioinformatics methodologies,we explored the differential expression of NCAPD2 between normal and tumor samples,along with its correlations with clinical-pathological characteristics,survival prognosis,and immune infiltration.Results:In the TCGA-LUAD dataset,tumor samples demonstrated significantly elevated levels of NCAPD2 expression compared to normal samples(p<0.001).Clinically,higher NCAPD2 expression was notably associated with advanced T,N,and M stages,pathologic stage,gender,smoking status,and diminished overall survival(OS).Moreover,differentially expressed genes(DEGs)associated with NCAPD2 were predominantly enriched in pathways related to cell division.Immune infiltration analysis revealed that NCAPD2 expression levels were linked to the infiltration of memory B cells,naïve CD4+T cells,activated memory CD4+T cells,and M1 macrophages.In vitro experiments demonstrated that silencing NCAPD2 suppressed LUAD cell proliferation,migration,invasion,epithelial-mesenchymal transition(EMT),and cell cycle progression.Conclusions:In summary,NCAPD2 may represent a promising prognostic biomarker and novel therapeutic target for LUAD.

Hydrangea serrata extract exerts tumor inhibitory activity against hepatocellular carcinoma HepG2 cells via inducing p27/CDK2-mediated cell cycle arrest and apoptosis

Objective:To examine the inhibitory effect of Hydrangea serrata extract against hepatocellular carcinoma HepG2 cells and its underlying mechanisms.Methods:The effects of Hydrangea serrata extract on growth inhibition of tumor cells and spheroids were assessed using MTT and 3D culture assays.Quantitative real-time PCR and Western blot analyses were employed to investigate the changes in mRNA and protein expression levels of molecules related to cell cycle and apoptosis.Results:Hydrangea serrata extract effectively inhibited the growth of both tumor cells and spheroids.The extract also significantly upregulated p27 mRNA expression and downregulated CDK2 mRNA expression,leading to cell cycle arrest.Moreover,increased BAX/Bcl-2 ratio as well as caspase-9 and-3 were observed after treatment with Hydrangea serrata extract,indicating the induction of tumor cell apoptosis.Conclusions:Hydrangea serrata extract has the potential to alleviate tumors by effectively modulating cell-cycle-related gene expressions and inducing apoptosis,thereby inhibiting tumor growth.

Antitumor Effect of Apcin on Endometrial Carcinoma via p21-Mediated Cell Cycle Arrest and Apoptosis

Objective Endometrial carcinoma(EC)is a prevalent gynecological malignancy characterized by increasing incidence and mortality rates.This underscores the critical need for novel therapeutic targets.One such potential target is cell division cycle 20(CDC20),which has been implicated in oncogenesis.This study investigated the effect of the CDC20 inhibitor Apcin on EC and elucidated the underlying mechanism involved.Methods The effects of Apcin on EC cell proliferation,apoptosis,and the cell cycle were evaluated using CCK8 assays and flow cytometry.RNA sequencing(RNA-seq)was subsequently conducted to explore the underlying molecular mechanism,and Western blotting and coimmunoprecipitation were subsequently performed to validate the results.Animal studies were performed to evaluate the antitumor effects in vivo.Bioinformatics analysis was also conducted to identify CDC20 as a potential therapeutic target in EC.Results Treatment with Apcin inhibited proliferation and induced apoptosis in EC cells,resulting in cell cycle arrest.Pathways associated with apoptosis and the cell cycle were activated following treatment with Apcin.Notably,Apcin treatment led to the upregulation of the cell cycle regulator p21,which was verified to interact with CDC20 and consequently decrease the expression of downstream cyclins in EC cells.In vivo experiments confirmed that Apcin treatment significantly impeded tumor growth.Higher CDC20 expression was observed in EC tissue than in nonmalignant tissue,and increased CDC20 expression in EC patients was associated with shorter overall survival and progress free interval.Conclusion CDC20 is a novel molecular target in EC,and Apcin could be developed as a candidate antitumor drug for EC treatment.

Analysis and Review of Downregulated Actin Cytoskeletal Proteins in Non-Small Cell Lung Cancer

Actin, a highly conserved protein, plays a dominant role in Non-small cell lung cancer (NSCLC). Late diagnosis and the aggressive nature of NSCLC pose a significant threat. Studying the clinic pathological properties of NSCLC proteins is a potential alternative for developing treatment strategies. Towards this, 35 downregulated actin cytoskeletal proteins on NSCLC prognosis and treatment were studied by examining their protein-protein interactions, gene ontology enrichment terms, and signaling pathways. Using PubMed, various proteins in NSCLC were identified. The protein-protein interactions and functional associations of these proteins were examined using the STRING database. The focal adhesion signaling pathway was selected from all available KEGG and Wiki pathways because of its role in regulating gene expression, facilitating cell movement and reproduction, and significantly impacting NSCLC. The protein-protein interaction network of the 35 downregulated actin cytoskeleton proteins revealed that ACTG1, ACTR2, ACTR3, ANXA2, ARPC4, FLNA, TLN1, CALD1, MYL6, MYH9, MYH10, TPM1, TPM3, TPM4, PFN1, IQGAP1, MSN, and ZXY exhibited the highest number of interactions. Whereas HSPB1, CTNNA1, KRT17, KRT7, FLNB, SEPT2, and TUBA1B displayed medium interactions, while UTRN, TUBA1B, and DUSP23 had relatively fewer interactions. It was discovered that focal adhesions are critical in connecting membrane receptors with the actin cytoskeleton. In addition, protein kinases, phosphatases, and adapter proteins were identified as key signaling molecules in this process, greatly influencing cell shape, motility, and gene expression. Our analysis shows that the focal adhesion pathway plays a crucial role in NSCLC and is essential for developing effective treatment strategies and improving patient outcomes.

Altered expression of nuclear matrix proteins in etoposide induced apoptosis in HL-60 cells

The events of cell death and the expression of nuclear matrix protein (NMP) have been investigated in a promyelocytic leukemic cell line HL-60 induced with etoposide. By means of TUNEL assay, the nuclei displayed a characteristic morphology change, and the amount of apoptotic cells increased early and reached maximun about 39% after treatment with etoposide for 2 h. Nucleosomal DNA fragmentation was observed after treatment for 4 h. The morphological change of HL-60 cells, thus, occurred earlier than the appearance of DNA ladder. Total nuclear matrix proteins were analyzed by 2-dimensional gel electrophoresis. Differential expression of 59 nuclear matrix proteins was found in 4 h etoposide treated cells. Western blotting was then performed on three nuclear matrix acssociated proteins, PML, HSC70 and NuMA. The expression of the suppressor PML protein and heat shock protein HSC70 were significantly upregulated after etoposide treatment, while NuMA, a nuclear mitotic apparatus protein, was down regulated. These results demonstrate that significant biochemical alterations in nuclear matrix proteins take place during the apoptotic process.

Wild pink bayberry free phenolic extract induces mitochondria-dependent apoptosis and G0/G1 cell cycle arrest through p38/MAPK and PI3K/Akt pathway in MDA-MB-231 cancer cells

Polyphenol-rich foods have been shown to be good for cancer prevention as powerful antioxidants. In this study, the mechanisms of wild pink bayberry free phenolic extract(WPBFE)inhibiting the proliferation and inducing apoptotic of MDA-MB-231 breast cancer cells was examined. The main phenolic acids and flavonols in WPBFE were gallic acid((18.83 ± 0.44)μg/g FW)and myricetin((1.52 ± 0.05)μg/g FW), respectively. The maximum inhibition rate of WPBFE at non-cytotoxicity dose(below 80 mg/mL)was 81%. Western blotting analysis showed that WPBFE could cause the arrest of cell cycle in G0/G1 phase by down-regulating expression levels of PCNA, CDK4, cyclin D1 and up-regulating the expression level of p21. Meanwhile, WPBFE induced apoptosis through initiating the mitochondrial death pathway by up-regulating cleaved caspase-3 and enhancing the ratio of Bax/Bcl-2, with the maximum expression levels of 1.29 and 2.03 folds that of control group, respectively. Further study of the upstream protein, we found that WPBFE down-regulated TRAF2, while upregulated p-ASK1, p-p38 and p-p53. Furthermore, WPBFE could down-regulate the expression of p-PI3K and p-Akt. These observations indicated that WPBFE might play an anticancer role through regulating the p38 MAPK together with PI3K/Akt pathway.

Cdk5 and aberrant cell cycle activation at the core of neurodegeneration

Neurodegenerative diseases are caused by the progressive loss of specific neurons.The exact mechanisms of action of these diseases are unknown,and many studies have focused on pathways related to abnormal accumulation and processing of proteins,mitochondrial dysfunction,and oxidative stress leading to apoptotic death.However,a growing body of evidence indicates that aberrant cell cycle re-entry plays a major role in the pathogenesis of neurodegeneration.The activation of the cell cycle in mature neurons could be promoted by several signaling mechanisms,including c-Jun N-terminal kinases,p38 mitogen-activated protein kinases,and mitogen-activated protein kinase/extracellular signal-regulated kinase cascades;post-translational modifications such as Tau-phosphorylation;and DNA damage response.In all these events,implicated Cdk5,a proline-directed serine/threonine protein kinase,seems to be responsible for several cellular processes in neurons including axon growth,neurotransmission,synaptic plasticity,neuronal migration,and maintenance of neuronal survival.However,under pathological conditions,Cdk5 dysregulation may lead to cell cycle re-entry in post-mitotic neurons.Thus,Cdk5 hyperactivation,by its physiologic activator p25,hyper-phosphorylates downstream substrates related to neurodegenerative diseases.This review summarizes factors such as oxidative stress,DNA damage response,signaling pathway disturbance,and Ubiquitin proteasome malfunction contributing to cell cycle re-entry in post-mitotic neurons.It also describes how all these factors are linked to a greater or lesser extent with Cdk5.Thus,it offers a global vision of the function of cell cycle-related proteins in mature neurons with a focus on Cdk5 and how this protein contributes to the development of Alzheimer’s disease,Parkinson’s disease,amyotrophic lateral sclerosis,and Huntington’s disease by cell cycle activation.

A pilot study of the relative number of circulating tumor cells and leukocytes containing actin-binding proteins in head and neck cancer patients

Circulating tumor cells(CTCs)play an important role in tumor metastases,which is positively correlated with an increased risk of death.Actin-binding proteins,including cofilin(CFL1),profilin 1(PFN1),and adenylate cyclase-associated protein 1(CAP1),are thought to be involved in tumor cell motility and metastasis,specifically in head and neck squamous cell carcinoma(HNSCC).However,currently,there are no published studies on CFL1,PFN1,and CAP1 in CTCs and leukocytes in HNSCC patients.We assessed serum levels of CFL1,PFN1,and CAP1 and the number of CTCs and leukocytes containing these proteins in blood from 31 HNSCC patients(T1-4N0-2M0).The analysis used flow cytometry and an enzyme-linked immunosorbent assay kit.We found that CAP1+CTCs and CAP1+leukocyte subpopulations were prevalent in these HNSCC patient samples,while the prevalence rates of CFL1+and PFN1+CTCs were relatively low.Patients with stage T2-4N1-2M0 had CFL1+and PFN1+CTCs with an elevated PFN1 serum level,compared with the T1-3N0M0 group.In summary,the PFN1 serum level and the relative number of PFN1+CD326+CTCs could be valuable prognostic markers for HNSCC metastases.The current study is the first to obtain data regarding the contents of actin-binding proteins(ABPs)in CTCs,and leukocytes in blood from HNSCC patients.This is also the first to assess the relationship between the number of CTCs subgroups and disease characteristics.

Combinatorial effect of diclofenac with piperine and D-limonene on inducing apoptosis and cell cycle arrest of breast cancer cells

Objective:To investigate the potential synergistic activity of diclofenac with piperine and D-limonene in inducing apoptosis and cell cycle arrest in breast cancer MCF-7 cells.Methods:Molecular docking study was conducted to evaluate the binding affinity of diclofenac with piperine and D-limonene against p53,Bax,and Bcl-2.The MTT assay was used to determine IC50,and the Chou-Talay method was used to determine the synergistic concentration of the combination treatment of diclofenac plus piperine and diclofenac plus D-limonene.Apoptosis detection,cell cycle arrest,reactive oxygen species production,and mitochondrial membrane potential were also investigated.Results:Diclofenac,piperine,and D-limonene showed potent binding affinity for p53,Bax,and Bcl-2.Diclofenac plus piperine and diclofenac plus D-limonene enhanced the formation of reactive oxygen species,which also had an effect on the mitochondrial membrane’s integrity and caused DNA fragmentation.Diclofenac plus piperine and diclofenac plus D-limonene arrested the cells in the sub-G0phase while drastically lowering the percentage of cells in the G2/M phase.Furthermore,the elevated apoptosis in the combined therapy was confirmed by annexin V/propidium iodide staining.Conclusions:The combined therapy prominently enhanced the antiproliferative and apoptotic effects on MCF-7 cells compared with treatment with diclofenac,piperine,and D-limonene alone.

Expression dynamics of periodic transcripts during cancer cell cycle progression and their correlation with anticancer drug sensitivity

Background:The cell cycle is at the center of cellular activities and is orchestrated by complex regulatory mechanisms,among which transcriptional regulation is one of the most important components.Alternative splicing dramatically expands the regulatory network by producing transcript isoforms of genes to exquisitely control the cell cycle.However,the patterns of transcript isoform expression in the cell cycle are unclear.Therapies targeting cell cycle checkpoints are commonly used as anticancer therapies,but none of them have been designed or evaluated at the alternative splicing transcript level.The utility of these transcripts as markers of cell cycle-related drug sensitivity is still unknown,and studies on the expression patterns of cell cycle-targeting drug-related transcripts are also rare.Methods:To explore alternative splicing patterns during cell cycle progression,we performed sequential transcriptomic assays following cell cycle synchronization in colon cancer HCT116 and breast cancer MDA-MB-231 cell lines,using flow cytometry and reference cell cycle transcripts to confirm the cell cycle phases of samples,and we developed a new algorithm to describe the periodic patterns of transcripts fluctuating during the cell cycle.Genomics of Drug Sensitivity in Cancer(GDSC)drug sensitivity datasets and Cancer Cell Line Encyclopedia(CCLE)transcript datasets were used to assess the correlation of genes and their transcript isoforms with drug sensitivity.We identified transcripts associated with typical drugs targeting cell cycle by determining correlation coefficients.Cytotoxicity assays were used to confirm the effect of ENST00000257904 against cyclin dependent kinase 4/6(CDK4/6)inhibitors.Finally,alternative splicing transcripts associated with mitotic(M)phase arrest were analyzed using an RNA synthesis inhibition assay and transcriptome analysis.Results:We established high-resolution transcriptome datasets of synchronized cell cycle samples from colon cancer HCT116 and breast cancer MDA-MB-231 cells.The results of the cell cycle assessment showed that 43,326,41,578 and 29,244 transcripts were found to be periodically expressed in HeLa,HCT116 and MDA-MB-231 cells,respectively,among which 1280 transcripts showed this expression pattern in all three cancer cell lines.Drug sensitivity assessments showed that a large number of these transcripts displayed a higher correlation with drug sensitivity than their corresponding genes.Cell cycle-related drug screening showed that the level of the CDK4 transcript ENST00000547281 was more significantly associated with the resistance of cells to CDK4/6 inhibitors than the level of the CDK4 reference transcript ENST00000257904.The transcriptional inhibition assay following M phase arrest further confirmed the M-phase-specific expression of the splicing transcripts.Combined with the cell cycle-related drug screening,the results also showed that a set of periodic transcripts,for example,ENST00000314392(a dolichylphosphate mannosyltransferase polypeptide 2 isoform transcript),was more associated with drug sensitivity than the levels of their corresponding gene transcripts.Conclusions:In summary,we identified a panel of cell cycle-related periodic transcripts and found that the levels of transcripts of drug target genes showed different values for predicting drug sensitivity,providing novel insights into alternative splicing-related drug development and evaluation.

Novel coumarone-derived(S,E)-4-(4-fluorobenzylidene)-3-phenylchroman-3-ol inhibits muscle-invasive bladder cancer cells by repressing the S and G2 cell cycle phases

Background:This study aimed to select compounds with unique inhibitory effects on muscle-invasive bladder cancer(MIBC)from coumarone derivatives with similar parent nuclear structures and to reveal their tumor-suppressive effects using various approaches.Methods:Bladder cancer cell lines SW780 and T24,as well as human normal bladder epithelial cell line SV-HUC-1 were selected as the study model,and these urinary system cells were co-incubated with various concentrations of(S,E)-4-(4-methylbenzylidene)-3-phenylchroman-3-ol,(S,E)-4-(4-isocyanobenzylidene)-3-phenylchroman-3-ol,(S,E)-4-(4-fluorobenzylidene)-3-phenylchroman-3-ol(FPO),and(S,E)-3-phenyl-4-(4-(trifluoromethoxy)benzylidene)chroman-3-ol.Cell activity was detected using cell counting kit-8.FPO showed the strongest inhibitory effect on MIBC cells;therefore,it was selected for further experiments.We monitored the FPO-induced T24 cell morphological changes with an inverted microscope.The FPO-inhibited migration of T24 cells was examined using a cell scratch assay.We detected the clonogenic ability of T24 cells through a clone formation test and evaluated their proliferative ability using a 5-ethynyl-2’-deoxyuridine fluorescence staining kit.The inhibitory effect of FPO against the cell cycle was monitored using flow cytometry,and its suppressive effect on the DNA replication ability of T24 cells was detected using double fluorescence staining(Ki67 and phalloidin).Results:Among the four candidate coumarone derivatives,FPO showed the most significant inhibitory effect on MIBC cells and was less toxic to normal urothelial cells.FPO inhibited T24 cell growth in time and dose-dependent manners(the half-inhibitory concentration is 8μM).FPO significantly repressed the proliferation,migration,and clonogenic ability of bladder cancer T24 cells.Cell mobility was significantly inhibited by FPO:30μM FPO almost completely repressed migration occurred at after 24 h treatment.Moreover,FPO significantly suppressed the clonogenicity of bladder cancer cells in a dose-dependent manner.Mechanistically,FPO targeted the cell cycle,arresting the S and G2 phases on bladder cancer T24 cells.Conclusion:We discovered a novel anticancer chemical,FPO,and proposed a potential mechanism,through which it suppresses MIBC T24 cells by repressing the cell cycle in the S and G2 phases.This study contributes to the development of novel anticancer drugs for MIBC.

Induction of apoptosis and G2/M cell cycle arrest by oridonin in human gastric cancer BGC-823 cells

Aim To investigate in vitro apoptosis-induction effects of oridonin on gastric tumor cells BGC-823 and its effects on cell cycle, mitochondrial membrane potential and intracellular Ca^2＋ to shed light on the mode of its anticancer action. Methods The MTT method was used to investigate the inhibitory effect of oridonin on BGC-823 cells. The apoptosis-induction effect was evaluated by confocal laser microscopy and flow cytometry. The change of mitochondrial membrane potential and the increase of intracellular Ca^2＋ were assessed by fluorescence probe rhodamine123 and Fluo 3-AM, respectively, with flow cytometry. The expression of apoptosis and cell cycle related proteins was studied using western blotting. Results Oridonin inhibited BGC-823 cells growth with IC50 of 22.21 p, mol.L^-1. It induced apoptosis in a dose-dependent manner. In addition, it decreased mitochondria membrane potential, increased intracellular Ca^2＋, and activated pro-caspase 3. BGC-823 cells were arrested in G2/M cell cycle phase with lower expression of cyclin A protein. The up-regulation of p53 was observed before apoptosis and cell cycle arrest occurred. Conclusion Oridonin inhibits the proliferation of BGC-823 cells through G2/M cell cycle arrest and apoptosis induction, which is mediated by influx of Ca^2＋, up-regulation of p53, activation of caspase-3, and down-regulation of cyclin A.

Effects of Low Dose Radiation on Tumor Apoptosis, Cell Cycle and Apoptosis-Related Protein Bcl-2 in Tumor-Bearing Mice

To study the effects of low dose radiation (LDR) on tumor apoptosis, cellcycle progression and changes of apoptosis-related protein Bcl-2 in tumor-bearing mice. Methods:Male mice of Kunming strain were implanted subcutaneously with S180 sarcoma cells in the left inguenas an in situ experimental animal model. Seven days later, the mice were subjected to 75 mGywhole-body γ-irradiation. At 24 and 48 h after the irradiation, all mice were sacrificed. The tumorsizes were measured, and tumor cell apoptosis and cell cycle progression were analyzed by flowcytometry. The expression of apoptosis-related protein Bcl-2 and the apoptotic rate of tumor cellswere observed by immunohistochemistry and electron microscopy. Results: Tumors grew significantlyslower after LDR (P 【 0.05). The tumor cells were arrested in G1 phrase and the expression of Bcl-2protein decreased at 24 h. Apoptotic rate of tumor cells was increased significantly at 48 h afterLDR (P 【 0.01). Conclusion: LDR could cause a G1-phase arrest and increase the apoptosis of tumorcells through the low level of apoptosis-related protein bcl-2 in the tumor-bearing mice. Theorganized immune function and anti-tumor ability are markedly increased after LDR. Our studyprovides practical evidence of clinical application to cancer treatment.

Cell Cycle Kinetic Analysis in the Cortical Regions of the Lentil Primary Root During Germination

Cell cycle kinetic activity in the cortical cells of the lentil (Lens culinaris Me-die. cv. Verte du Puy) primary root during germination was examined both temporally and spatially. Immunohistochemical and cytological evidence indicated that DNA replication and cell division started in the cortical cells of tire lentil primary root after around 13 and 17 h of imbibition, respectively. The first cells in DNA synthesis and the First mitotic figures all appeared in the cortical cells about I mm front the root-cap junction, but these divided cells had synthesized their DNA during the maturity of seed instead of during germination. The kinetic pattern of activity of the first cell cycle showed that these cells were not activated synchronously, but re-entered the cell cycle in turn depending on their places in the root tip, However, the adjacent cells partially synchronously proceeded their cell cycle.

Multiple Defects of Cell Cycle Checkpoints in U937-ASPI3K, an U937 Cell Mutant Stably Expressing Anti-Sense ATM Gene cDNA

(Ataxia-telangiectasia mutated gene (ATM) functions in control of cell cycle checkpoints in responding to DNA damage and protects cells from undergoing apoptosis. Knock-out within tumor cells of endogenous ATM will achieve therapeutic benefits and enable a better understanding of the decisive mechanisms of cell death or survival in response to DNA damaging agents. ) In present paper, we sought to characterize the cell cycle checkpoint profiles in U937-ASPI3K, a U937 cell mutant that was previously established with endogenous ATM knock-out phenotype. Syn- chronized U937-ASPI3K was exposed to 137Cs irradiation, G1, S. G2/M cell cycle checkpoint pro- files were evaluated by determining cell cycle kinetics, p53/p21 protein, cyclin dependent kinase 2 (CDK2) and p34CDC2 kinase activity in response to irradiation. U937-ASPI3K exhibited multiple defects in cell cycle checkpoints as defined by failing to arrest cells upon irradiation. The accumulation of cellular p53/p21 protein and inhibition of CDK kinase was also abolished in U937-ASPI3K. It was concluded that the stable expression of anti-sense PI3K cDNA fragment completely abolished multiple cell cycle checkpoints in U937-ASPI3K, and hence U937-ASPI3K with an AT-like phenotype could serves as a valuable model system for investigating the signal transduction pathway in responding to DNA damaging-based cancer therapy.

A Novel Three-parameter Flow Cytometric Analysis for Cell Cycle

To set up a three-parameter method for cell cycle analysis by two-laser flowcy-tometer, which can detect two types of cyclin plus DNA content in one measurement, and thatanalyze unscheduled expression of cyclins. Methods: Three-color fluorescence was used for analysisof two types of cyclins and DNA content simultaneously in individual cells by two-laser flowcytometry. MOLT-4 cells were used to study the expression of major cyclins in mammalian cells. ATriton-X100 permeabilization procedure was optimized for detection of two types of cyclins. Onecyclin was stained directly with a FITC-conjugated monoclonal antibody (mAb), and the other,indirectly with RPE-Cy5-conjugated secondary antibody, while DNA was stained with the fluorochromeDAPI. mAMSA and mimosine treated MOLT-4 cells were used to test this three-parameter method.Results: Permeabilization with 0.5% Triton-XlOO in PBS containing 1% BSA for 5 min on ice providedoptimal conditions for the simultaneous labelling of two cyclins plus DNA in single cells. It wasfound that the emission spectrum of the three dyes (DAPI, FITC and RPE-Cy5) could be measured withno compensation. Based on cyclinA/cyclinE/DNA flow cytometric analysis, asynchronously growingMOLT-4 cells could be divided into 6 compartments (G1o, G1e, G1l, S, G2, and M) simultaneously,allowing for analysis of cell cycle phase specific perturbations without the necessity of cellsynchronization. Unscheduled cyclin B1 expression was observed in G1 cells treated with mimosine andcyclin E in G2 cells treated with mAMSA. We found that unscheduled cyclin expression paralleledexpected cyclin expression. Conclusion: Thus, three-color FCM analysis of cells may not only beapplied to measure unscheduled vs. expected cyclin expression but may also be used to estimate thefraction of cycling cells in up to 6 cell populations.