Curcumin down-regulates PCNA, cyclin D1 and Bcl-XL expression in human keratinocyte cell lines

Objective：To evaluate the effects of curcumin on regulating the proliferation,cell cycle distribution,apoptosis and relevant mechanisms in keratinocyte cell lines.Methods：The human immortalized human keratinocyte lines（HaCaT cells） were treated with different doses of curcumin.The effects of curcumin on cell viability were measured by MTT assay,and the cell cycle distribution and apoptosis determined by flow cytometry.The mRNA expression changes of proliferating cell nuclear antigen（PCNA）,cyclin D1 and Bcl-xL were from real-time PCR analysis and the protein levels were detected by Western blotting.Results：Data obtained in the study showed that curcumin could cause significantly inhibitory effect on proliferation in HaCaT cells in a time- and dose-dependent manner.Cell arrest at G1/S phase and significant apoptosis were observed after being treated with curcumin for 24 h.In association with these,the expression of PCNA,cyclin D1 and Bcl-xL were decreased both at mRNA and protein levels for the same treatment.Conclusion：Curcumin can inhibit proliferation,induce cell arrest at G1/S phase and cause apoptosis in HaCaT cells.The decreased expression of PCNA,cyclin D1 and Bcl-xL induced by curcumin contributes to the above effects in vitro.     

Arsenic Trioxide Inhibits Proliferation in K562 Cells by Changing Cell Cycle and Survivin Expression

To study the mechanisms involved in the inhibition of chronic myeloid leukemic cells (K562) proliferation induced by arsenic trioxide (As2O3) and to explore the potential role of Survivin, an inhibitor of apoptosis protein, in the regulation of As203 induced cell apoptosis, K562 cells were cultured with As203 of different concentrations. Cells were collected for proliferation analysis by MTT assay. Cell cycle distribution and cell apoptosis were analyzed by flow cytometry. Expression of Survivin protein and mRNA were detected by flow cytometry and RT-PCR, respectively. Our results showed that As2O3 (2-10/μmol/L) inhibited K562 cells growth effectively, but it did not induce cells apoptosis significantly. The percentage of K562 cells at G2/M phase increased in proportion to As2O3 concentrations, and the expression of Survivin mRNA and content of Survivin protein was up-regulated accordingly. It is concluded that As2O3 inhibited K562 cells growth by inducing cell cycle arrest mainly at G2/M phase. Over-expression of Survivin gene and protein might be one of the possible mechanisms contributing to K562 cells‘ resistance to As2O3-induced apoptosis.     

Paris saponin I induces G<Subscript>2</Subscript>/M cell cycle arrest and apoptosis in human gastric carcinoma SGC7901 cells

The aim of this study was to investigate the effect of Paris saponinⅠ(PSⅠ)on human gas-tric carcinoma cell growth and apoptosis and to explore the potential mechanisms.The proliferation of SGC7901 cells was monitored by the MTT cell viability assay,while the nuclear morphology of apoptotic cells was assessed by Hoechst 33258 staining.Flow cytometry was performed to analyze the cell cycle progression of propidium iodide(PI)-stained SGC7901 cells and the apoptotic rate of annex-inⅤ/PI-stained cells.Western blotting was used to examine the expression of several cell cycle proteins,including cyclin B1 and Cdk1,and the apoptosis-regulated proteins Bcl-2,Bax,cytochrome c,procas-pase-9,and procaspase-3.The MTT assay demonstrated that PSⅠ could induce significant dose-and time-dependent inhibition of SGC7901 cell proliferation.Marked morphological changes,including condensation of chromatin,nuclear fragmentation and apoptotic bodies were clearly shown on Hoechst 33258 staining.PSⅠ treatment also resulted in the disruption of the cell cycle at G2/M and the induction of apoptosis.Following PSⅠ treatment,the cell cycle-related proteins cyclin B1 and Cdk1 were down-regulated.Expression of the pro-apoptotic protein Bax was increased,while anti-apoptotic protein Bcl-2 decreased.PSⅠ treatment resulted in elevated cytoplasmic cytochrome c and activation of the apoptotic proteases caspase-9 and caspase-3.These data indicate that PSⅠ acts as an inhibitor of proliferation in SGC7901 cells by inducing cell cycle arrest and mitochondria-dependent apoptosis.PSⅠ is a potential therapeutic agent against human gastric carcinoma.     

Induction of apoptosis in human Hep3B hepatoma cells by norcantharidin through a p53 independent pathway via TRAIL/DR5 signal transduction

<正>Objective:To investigate the inhibitory activities of norcantharidin(NCTD),a demethylated analogue of cantharidin,on Hep3B cells(a human hepatoma cell line) with deficiency of p53.Methods:The survival rate of the Hep3B cells after treating with NCTD was measured by MTT assay.Cell cycle of treated cells was analyzed by flow cytometry,and DNA fragmentation was observed by electrophoresis.The influence of inhibitors for various caspases and anti-death receptors antibodies on the NCTD-induced apoptosis in the cells was determined. Results:NCTD treatment resulted in growth inhibition of Hep3B cells in a dose- and time-dependent manner.Cell cycle analysis of the cells after treatment with NCTD for 48 h shows that NCTD induced G_2M phase arrest occurs at low concentration(≤25μmol/L) but G_0G_1 phase arrest at high concentration(50μmol/L).The addition of both caspase-3 and caspase-10 inhibitors completely inhibited DNA fragmentation.Addition of anti-TRAIL/DR5 antibody significantly inhibited DNA fragmentation.Conclusion:NCTD may inhibit the proliferation of Hep3B cells by arresting cell cycle at G_2M or G_0G_1 phase,and induce cells apoptosis via TRAIL/DR5 signal transduction through activation of caspase-3 and caspase-10 by a p53-independent pathway.     

Carvacrol Promotes Cell Cycle Arrest and Apoptosis through PI3K/AKT Signaling Pathway in MCF-7 Breast Cancer Cells

Objective: To examine the role of carvacrol in modulating PI3K/AKT signaling involved in human breast cancer pathogenesis using in vitro experimental model MCF-7 cells. Methods: MTT and lactate dehydrogenase assays were performed with cells treated with different doses of carvacrol (0–250 μ mol/L) at different time points (24 and 48 h). The nuclear morphology was assessed in MCF-7 cells with propidium iodide (PI) and acridine orange/ethidium bromide (AO/EB) staining and analyzed by fluorescence microscopy. Events like cell cycle arrest and apoptosis were observed by flow cytometric analysis and expressions of p-Rb, cyclin D1, cyclin-dependent kinase 4 (CDK4), CDK6, Bax, Bcl-2, PI3K/p-AKT were analyzed by immunoblot. Results: Carvacrol significantly reduced cell viability with the half maximal inhibitory concentration value of 200 μ mol/L at 24 and 48 h (P<0.05). importantly, there was a significant increase in the accumulation of the G0/G1 phase upon treatment with carvacrol in MCF-7 cells (P<0.05 or P<0.01). A remarkable decrease in protein expressions of p-Rb, cyclin D1, CDK4 and CDK6 denoted cell cycle arrest (P<0.05 or P<0.01). In addition, carvacrol treatment significantly inhibited PI3K/p-AKT protein expressions leading to induction of apoptosis mediated by decreased Bcl2 and increased Bax protein expressions. Further, Annexin V/PI staining by FACS analysis, dual staining by AO/EB and PI staining studies suggested induction of apoptosis by carvacrol through PI3K/Akt signaling pathway in MCF-7 cells. Conclusion: Carvacrol significantly inhibited the breast cancer MCF-7 cell proliferation and induced apoptosis via suppressing PI3/AKT signaling pathway.     

Down-regulation of p110β expression increases chemosensitivity of colon cancer cell lines to oxaliplatin

This study examined the synergetic effect of class ?A Phosphoinositide 3-kinases cata-lytic subunit p110β knockdown in conjunction with oxaliplatin treatment on colon cancer cells. Down-regulation of p110β by siRNA interference and oxaliplatin treatment were applied in colon cancer cell lines HT29, SW620 and HCT116. MTT assay was used to measure the inhibitory effect of p110β knockdown on the proliferation of colon cancer cell lines. SubG1 assay and Annexin-Ⅴ FITC/PI double-labeling cytometry were applied to detect cell apoptosis. And cell cycle was evalu-ated by using PI staining and flow cytometry. The expression of caspase 3, cleaved PARP, p-Akt, T-Akt and p110β was determined by western blotting. The results suggested that down-regulation of p110β expression by siRNA obviously reduced cell number via accumulation in G0-G1 phase of the cell cycle in the absence of notablely increased apoptosis in colon cancer cell lines HT29 and SW620 (S phase arrest in HCT116). Moreover, inhibition of p110β expression increased oxaliplatin-induced cell apoptosis and cell cycle arrest in HT29, HCT116 and SW620 cell lines. In addition, increases of cleaved caspase-3 and cleaved PARP induced by oxaliplatin treatment were determined by im-munoblotting in p110β knockdown group compared with normal control group and wild-type group. It is concluded that down-regulated expression of p110β could inhibit colon cancer cells proliferation and result in increased chemosensitivity of colorectal cancer cells to oxaliplatin through augmentation of oxaliplatin-induced cell apoptosis and cell cycle arrest.     

Comparison between synthetic retinoid CD437 and acitretin inhibiting melanoma A375 cell in vitro

Objective:To investigate the effects of synthetic retinoid CD437 and acitretin on cell proliferation,apoptosis,cycle arrest and Bax/Bcl-2 protein expression of melanoma A375 cell.Methods:MTT assay was used to determine the anti-proliferative effects of CD437 and acitretin on melanoma A375 cell.Flow cytometry was performed to investigate the influence of CD437 and acitretin on cell cycle and cell apoptosis.SABC immunocytochemistry was employed for detection of Bax/bcl-2 protein expressions.Results:10-5 mol/L CD437 was more effective than acitretin in inhibiting proliferation and inducing apoptosis of A375 cell after 24 h treatment,growth inhibiting ratio and apoptosis ratio(58.6%vs43.25% and 28.03%vs17.13%,P < 0.05 respectively).CD437 promoted G0/G1 arrest in melanoma A375 cell,however acitretin could not.CD437 and acitretin could up-regulate the expression of Bax protein and down-regulate the expression of bcl-2 protein(P < 0.05).Conclusion:CD437 is more effective than acitretin in inhibiting proliferation and inducing apoptosis and cycle arrest on A375 cell.CD437 may have more potentialities than acitretin for subsidiary treatment of melanoma.Mitochondrial apoptosis pathway is partially involved in two drugs inducing apoptosis on A375 cell.     

Inhibition of survivin expression and mechanisms of reversing drug-resistance of human lung adenocarcinoma cells by siRNA

Background Survivin, a member of the inhibitor of apoptosis protein （IAP） family, overexpresses in tumor cells and not expresses in terminally differentiated adult tissues. This study aimed to investigate the effects of survivin-specific siRNA on cell proliferation, apoptosis and chemosensitivity to cisplatin in vitro and in vivo and explore the mechanisms about decreasing expression of survivin in reversing cancer cells resistance to chemotherapeutic drug.Methods Survivin-specific siRNA was transfected into A549/DDP cells. The expression of survivin and lung resistance-related protein （LRP） mRNA levels were determined by RT-PCR, chemosensitivity of A549/DDP （cisplatin）cells to cisplatin was determined by MTT assay, and apoptosis and cell cycle were determined by flow cytometry （FCM）.The protein expression levels of survivin, LRP, cyclin-D1, caspase-3 and bcl-2 were determined by Western blotting analyses. The effect of survivin siRNA inhibition on tumor growth was studied in athymic nude mice in vivo.Results Survivin-specific siRNA efficiently down-regulated survivin expression. The cell cycle was arrested at G2/M phase, and apoptosis was obviously found. Inhibition of survivin expression could make the IC50 and drug-resistant index of cisplatin decrease, and enhance the cancer cells sensitivity to cisplatin. After transfection by survivin-specific siRNA, expression of LRP and cyclin-D1 were downregulated, caspase-3 expression was upregulated, bcl-2 expression had no obvious change. The animal experiment confirmed knockdown of survivin could inhibit the tumor growth.Conclusions Survivin-specific siRNA can efficiently suppress the expression of survivin, increase apoptosis, inhibit cells proliferation and enhance the chemosensitivity to cisplatin in vitro and in vivo. Suppression of survivin expression helping to reverse drug-resistance may have relationship with downregulation of LRP and upregulation of caspase-3.Anti-tumor strategies based on the inhibition of survivin may be useful in targeting lung adenocarcinomas.     

Focal adhesion kinase antisense oligodeoxynucleotides inhibit human pulmonary artery smooth muscle cells proliferation and promote human pulmonary artery smooth muscle cells apoptosis

Background Pulmonary artery smooth muscle cell (PASMC) proliferation plays an important role in pulmonary vessel structural remodelling. At present, the mechanisms related to proliferation of PASMCs are not clear. Focal adhesion kinase (FAK) is a widely expressed nonreceptor protein tyrosine kinase. Recent research indicates that FAK is implicated in signalling pathways which regulate cytoskeletal organization, adhesion, migration, survival and proliferation of cells. Furthermore, there are no reports about the role of FAK in human pulmonary artery smooth muscle cells (HPASMCs). We investigated whether FAK takes part in the intracellular signalling pathway involved in HPASMCs proliferation and apoptosis, by using antisense oligodeoxynucleotides (ODNs) to selectively suppress the expression of FAK protein. Methods Cultured HPASMCs stimulated by fibronectin (4μg/ml) were passively transfected with ODNs, sense FAK, mismatch sense and antisense-FAK respectively. Expression of FAK, Jun NH2-temlinal kinase (JNK), cyclin-dependent kinase 2 (CDK 2) and caspase-3 proteins were detected by immunoprecipitation and Western blots. Cell cycle and cell apoptosis were analysed by flow cytometry. In addition, cytoplasmic FAK expression was detected by immunocytochemical staining. Results When compared with mismatch sense group, the protein expressions of FAK, JNK and CDK 2 in HPASMCs decreased in antisense-FAK ODNs group and increased in sense-FAK ODNs group significantly. Caspase-3 expression upregulated in HPASMCs when treated with antisense ODNs and downregulated when treated with sense ODNs. When compared with mismatch sense ODNs group, the proportion of cells at G1 phase decreased significantly in sense ODNs group, while the proportion of cells at S phase increased significantly. In contrast, compared with mismatch sense ODNs group, the proportion of cells at G1 phase was increased significantly in antisense-FAK ODNs group. The level of cell apoptosis in antisense-FAK group was higher than in the mismatch sense group and the latter was higher than sense-FAK group. In addition, the sense-FAK ODNs group was strongly stained by immunocytochemistry, whereas the antisense-FAK ODNs group was weakly stained. Conclusions The results suggest that FAK relates to the proliferation of HPASMCs Antisense-FAK ODNs inhibit HPASMCs proliferation and facilitate their apoptosis. It is possible that FAK via JNK, CDK 2 signalling pathways enhances HPASMCs proliferation and via caspase-3 inhibits HPASMCs apoptosis.     

Effects of Trichostatin A on HDAC8 Expression, Proliferation and Cell Cycle of Molt-4 Cells

The effects of Trichostatin A (TSA) on histone deacetylase 8 (HDAC8) expression, proliferation and cell cycle arrest in T-lymphoblastic leukemia cell line Molt-4 cells in vitro were investigated. The effect of TSA on the growth of Molt-4 cells was studied by MTT assay. Flow cytometry was used to examine the cell cycle. The expression of HDAC8 was detected by using immunocyto-chemistry and Western blot. The results showed that proliferation of Molt-4 cells was inhibited in TSA-treated group in a time- and dose-dependent manner. The IC50 of TSA exposures for 24 h and 36 h were 254.3236 and 199.257μg/L respectively. The cell cycle analysis revealed that Molt-4 was mostly in G0/G1 phase, and after treatment with TSA from 50 to 400μg/L for 24 h, the percents of G0/G1 cells were decreased and cells were arrested in G2/M phase. Treatment of TSA for 24 h could significantly inhibit the expression of HDAC8 protein in Molt-4 cells (P<0.01). It was concluded that TSA could decrease the expression of HD AC8 in Molt-4 cells, which contributed to the inhibition of proliferation and induction of cell cycle arrest in Molt-4 cells.     

Anticancer effect of icaritin on human lung cancer cells through inducing s phase cell cycle arrest and apoptosis

Icaritin, a prenylflavonoid derivative from Epimedium Genus, has been shown to exhibit many pharmacological and biological activities. However, the function and the underlying mechanisms of icaritin in human non-small cell lung cancer have not been fully elucidated. The purpose of this study was to investigate the anticancer effects of icaritin on A549 cells and explore the underlying molecular mechanism. The cell viability after icaritin treatment was tested by MTT assay. The cell cycle distribution, apoptosis and reactive oxygen species（ROS） levels were analyzed by flow cytometry. The mRNA and protein expression levels of the genes involved in proliferation and apoptosis were respectively detected by RT-PCR and Western blotting. The results demonstrated that icaritin induced cell cycle arrest at S phase, and down-regulated the expression levels of S regulatory proteins such as Cyclin A and CDK2. Icaritin also induced cell apoptosis characterized by positive Hoechst 33258 staining, accumulation of the Annexin V-positive cells, increased ROS level and alteration in Bcl-2 family proteins expression. Moreover, icaritin induced sustained phosphorylation of ERK and p38 MAPK. These findings suggested that icaritin might be a new potent inhibitor by inducing S phase arrest and apoptosis in human lung carcinoma A549 cells.     

Enhanced effects of TRAIL-endostatin-based double-gene-radiotherapy on suppressing growth, promoting apoptosis and inducing cell cycle arrest in vascular endothelial cells

This study examined the effects of TRAIL-endostatin-based gene-radiotherapy on cellu-lar growth, apoptosis and cell cycle progression in human vascular endothelial cells ECV304 in vitro. The expression of TRAIL and endostatin protein in ECV304 cells was detected by ELISA after the transfection of recombinant plasmid pshuttle-Egr1-shTRAIL-shES and X-ray irradiation. Then MTT assay was used for determining the cellular proliferation, and flow cytometry (FCM) plus Annexin V and propidium iodide (PI) double-staining or PI single-staining were employed for the detection of apoptosis and cell cycle progression. The results showed that expression of TRAIL and endostatin protein exhibited a time- and dose-dependent change in ECV304 cells after pshut-tle-Egr1-shTRAIL-shES transfection in conjunction with irradiation. In the TRAIL-endostatin-based single- or double-gene-radiotherapy, the cell viability declined in a time- and dose-dependent manner, the percentage of cells at G2/M phase and apoptotic rate was increased, and the percentage of cells at G0/G1 phase was lowered as compared with those receiving radiotherapy alone. Moreover, TRAIL-endostatin-based double-gene-radiotherapy demonstrated better effects on growth inhibition, promotion of apoptosis and induction of cell cycle arrest in ECV304 cells than sin-gle-gene-radiotherapy.     

Effects of Betulinic Acid on Proliferation and Apoptosis in Jurkat Cells and Its In Vitro Mechanism

The anti-cancer effects of betulinic acid (BA) on Jurkat cells and its in vitro mechanism were examined by using MTT assay. Apoptosis was detected by using Hoechst33258 staining and annexin-Ⅴ/PI double-labeled cytometry. The effects of betulinic acid on the cell cycle of Jurkat cells were studied by propidium iodide method. RT-PCR and Western blotting were used to analyze the changes of cyclin D3, bcl-xl mRNA and protein levels in Jurkat cells after treatment with betulinic acid. Our results showed the proliferation of Jurkat cells was decreased in betulinic acid-treated group with a 24-h IC50 value being 70.00 μmol/L. Betulinic acid induced apoptosis of Jurkat cells in a time-and dose-dependent manner. The number of Jurkat cells treated with betulinic acid showed an increase in G0/G1 phase and decrease in S phase. After treatment with 0, 20, 60, 100 μmol/L betulinic acid for 24 h, the number of Jurkat cells was increased from (31.00±1.25)% to (58.84±0.32)% in G0/G1 phase, whereas it was decreased from (61.45±1.04)% to (35.82±1.95)% in S phase. PBMCs were less sensitive to the cytotoxicity of betulinic acid than Jurkat cells. The expressions of cyclin D3, bcl-xl mRNA and protein were decreased sharply in Jurkat cells treated with betulinic acid. It is concluded that betulinic acid is able to inhibit the proliferation of Jurkat cells by regulating the cell cycle, arrest cells at G0/G1 phase and induce the cell apoptosis. The anti-tumor effects of betulinic acid are related to the down-regulated expression of cyclin D3 and bcl-xl.     

Anticancer Effect of Total Annonaceous Acetogenins on Hepatocarcinoma

Objective:To confirm the anticancer effect of total annonaceous acetogenins(TAAs)abstracted from Annona squamosa Linn,on human hepatocarcinoma.Methods:The inhibitory effect of TAAs was demonstrated in H_(22)-bearing mice.The potency of TAAs was confirmed as its 50%inhibiting concentration(IC_(50))on Bel-7402 cell under Sulfur Rhodamine B staining.Both underlying mechanisms were explored as cellular apoptosis and cell cycle under flow cytometry.Mitochondrial and recipient apoptotic pathways were differentiated as mitochondrial membrane potential under flow cytometry and caspases activities under fluorescence analysis.Results:The inhibitory rate of TAAs in mice was 50.98%at 4 mg/kg dose.The IC_(50)of TAAs on Bel-7402 was20.06μg/mL(15.13-26.61μg/mL).Effective mechanisms of TAAs were confirmed as both of arresting cell cycle at G_1 phase and inducing apoptosis dose-and time-dependently.Mitochondrial and recipient pathways involved in apoptotic actions of TAAs.Conclusion:TAAs is effective for hepatocarcinoma,via inhibiting proliferation and inducing apoptosis.     

Low dose hyper-radiosensitivity in human lung cancer cell line A549 and its possible mechanisms

The low dose hyper-radiosensitivity （HRS） in human lung cancer cell line A549 was investigated, the changes of ATM kinase, cell cycle and apoptosis of cells at different doses of radiation were observed, and the possible mechanisms were discussed. A549 cells in logarithmic growth phase were irradiated with ^60Co y-rays at doses of 0-2 Gy. Together with flow cytometry for precise cell sorting, cell survival fraction was measured by means of conventional colony-formation assay. The expression of ATM1981 Ser-P protein was examined by Western blot 1 h after radiation. Apoptosis was detected by Hoechst 33258 fluorescent staining, and Annexin V-FITC/PI staining flow cytometry 24 h after radiation. Cell cycle distribution was observed by flow cytometry 6, 12 and 24 h after radiation. The results showed that the expression of ATM1981Ser-P protein was observed at 0.2 Gy, followed by an increase at 〉0.2 Gy, and reached the peak at 0.5 Gy, with little further increase as the dose exceeded 0.5 Gy. Twenty-four h after radiation, partial cells presented the characteristic morphological changes of apoptosis, and the cell apoptosis curve was coincident with the survival curve. As compared with control group, the cell cycle almost had no changes after exposure to 0.1 and 0.2 Gy radiation （P〉0.05）. After exposure to 0.3, 0.4 and 0.5 Gy radiation, G2/M phase arrest occurred 6 and 12 h after radiation （P〈0.05）, and the ratio of G2/M phase cells was decreased 24 h after radiation （P〈0.05）. It was concluded that A549 cells displayed the phenomenon of HRS/IRR. The mode of cell death was mainly apoptosis. The activity of ATM and cell cycle change may take an important role in HRS/IRR.     

Discovery of chrysoeriol,a PI3K-AKT-mTOR pathway inhibitor with potent antitumor activity against human multiple myeloma cells <Emphasis Type="Italic">in vitro</Emphasis>

This study was designed to determine the impact of chrysoeriol on proliferation and cell cycle progression in the human multiple myeloma cell lines RPMI 8226 and KM3,and its related molecular mechanisms.Chryseoriol was identified by using the phosphorylated AKT-specific cytoblot high throughput assay.CCK-8 assay was employed to examine the growth inhibition rate and IC 50 (48 h) in peripheral blood mononuclear cells (PBMNCs),RPMI 8226 and KM3 cells treated with chrysoeriol at various concentrations.Cells were labeled with 5-6-carboxyfluorescein diacetate succinimidyl ester (CFSE),and the proliferation dynamics was detected by flow cytometry and analyzed with ModFit software.The cell cycles of RPMI 8226 and KM3 cells were measured by flow cytometry when the IC 50 concentration of chrysoeriol was adopted.The alterations in cell-cycle related proteins (Cyclin B1,Cyclin D1,p21) and proteins in PI3K-AKT-mTOR pathway were determined by Western blot analysis.The results showed the proliferation of multiple myeloma cells was significantly inhibited by chrysoeriol,resulting in cell cycle arrest in G 2 /M phase.Chrysoeriol could significantly reduce the expression of p-AKT (s473) and p-4eBP1 (t37/46) protein,meanwhile enhanced Cyclin B1 and p21 protein expression.Similar effects were not observed in PBMNCs from normal donors.It was concluded that chrysoeriol was a selective PI3K-AKT-mTOR pathway inhibitor.It restrained the proliferation of human multiple myeloma cells,but didn’t affect proliferation of PBMNCs from normal donors.It might exhibit the cell cycle regulatory effect via the inhibition of PI3K-AKT-mTOR signal pathway.     

Inhibitive effect of 3-bromopyruvic acid on human breast cancer MCF-7 cells involves cell cycle arrest and apoptotic induction

Background Breast cancer is one of the most common malignancies in women and is highly resistant to chemotherapy Due to its high tumour selectivity, 3-bromopyruvic acid （3-BrPA）, a well-known inhibitor of energy metabolism has been proposed as a specific anticancer agent. The present study determined the effect of 3-BrPA on proliferation, cell cycle and apoptosis in the human breast cancer MCF-7 cell line and other antitumour mechanisms. Methods MCF-7 cells were treated with various concentrations of 3-BrPA for 1-4 days, and cell growth was measured by 3-（4, 5-dimethylthiazol-2-yl）-2, 5-diphenyl tetrazolium bromide assay. Marked morphological changes in MCF-7 cells after treatment with 3-BrPA were observed using transmission electron microscopy. The distributions of the cell cycle and apoptosis were analyzed by flow cytometry. Immunohistochemistry was used to indicate the changes in the expression of Bcl-2, c-Myc, and mutant p53. Results 3-BrPA （25 μg/ml） significantly inhibited the proliferation of MCF-7 cells in a time-dependent manner. The MCF-7 cells exposed to 3-BrPA showed the typical morphological characteristics of apoptosis, including karyopycnosis, nuclear condensation and oversize cytoplasmic particles. In addition, flow cytometric assay also showed more apoptotic cells after 3-BrPA stimulation. The cells at the GO and G1 phases were dramatically decreased while cells at the S and G2/M phases were increased in response to 3-BrPA treatment after 48 hours. Furthermore, 3-BrPA stimulation decreased the expressions of Bcl-2, c-Myc and mutant p53, which were strongly associated with the programmed cell death signal transduction pathway. Conclusion 3-BrPA inhibits proliferation, induces S phase and G2/M phase arrest, and promotes apoptosis in MCF-7 cells, which processes might be mediated by the downregulation of the expressions of Bcl-2, c-Myc and mutant p53.