Oridonin-induced mitochondria-dependent apoptosis in esophageal cancer cells by inhibiting PI3K/AKT/mTOR and Ras/Raf pathways.

Oridonin, an active diterpenoid isolated from Rabdosia rubescens, has been reported for its antitumor activity on several cancers. However, its effect on human esophageal cancer remains unclear. In this study, we demonstrated that oridonin could inhibit the growth of human esophageal cancer cells both in vitro and in vivo. Oridonin not only suppressed the proliferation, but also induced cell cycle arrest and mitochondrial-mediated apoptosis in KYSE-30, KYSE-150, and EC9706 cells with dose-dependent manner. Further mechanism studies revealed that oridonin led cell cycle arrest in esophageal cancer cells via downregulating cell cycle-related proteins, such as cyclin B1 and CDK2, while upregulating p53 and p21. Oridonin also increased proapoptotic protein Bax and reduced antiapoptotic protein Bcl-2, as well as the increased expression of cleaved caspase-3, -8, and -9. In addition, oridonin treatment could significantly inhibit the PI3K/Akt/mTOR and Ras/Raf signaling pathway. In vivo results further demonstrated that oridonin treatment markedly inhibited tumor growth in the esophageal cancer xenograft mice model. Taken together, these results suggest that oridonin may be a potential anticancer agent for the treatment of esophageal cancer.

Effect of CCNB1 silencing on cell cycle, senescence, and apoptosis through the p53 signaling pathway in pancreatic cancer.

Pancreatic cancer (PC) is a serious malignancy with high mortality and poor prognosis due to nonspecific incipient symptoms and early metastasis. Also, increasing evidence indicates that a panel of genes is newly identified in the pathogenesis of PC. As is a regulatory subunit, elevated cyclin B1 (CCNB1) expression has been detected in different cancers including PC. This study is designed to investigate the effects of CCNB1 silencing on cell cycle, senescence, and apoptosis through the p53 signaling pathway in PC. PC tissues and normal pancreatic tissues were collected. Cells were transfected and assigned into different groups. The expressions of CCNB1, p53, MDM2, Bax, caspase-9, caspase-3, and p21 in tissues and cells were detected by reverse transcription quantitative polymerase chain reaction and western blot analysis. ß-Galactosidase staining, MTT assay, and flow cytometry were conducted to test cell senescence, proliferation, cell cycle, and apoptosis. PC tissues showed higher expressions of CCNB1 and MDM2 and lower expressions of Bax, caspase-9, caspase-3, and p21. Cells transfected with shCCNB1 had lower expressions of CCNB1 and MDM2, whereas higher expressions of Bax, caspase-9, caspase-3, p53, and p21. The shCCNB1 group had decreased proliferation and S-phase cell proportion and increased apoptosis, senescence, and G0/G1-phase cell proportion. The PFT-α group showed higher expressions of MDM2 and lower expressions of Bax, caspase-9, caspase-3, p53, and p21. The PFT-α group had increased proliferation and S-phase cell proportion and declined apoptosis, senescence, and G0/G1-phase cell proportion. CCNB1 silencing inhibits cell proliferation and promotes cell senescence via activation of the p53 signaling pathway in PC.

FOXM1 promotes proliferation in human hepatocellular carcinoma cells by transcriptional activation of CCNB1.

The transcription factor Forkhead box protein M1 (FOXM1) plays critical roles in cancer development and progression, including human hepatocellular carcinoma (HCC). However, the regulatory role and underlying mechanisms of FOXM1 is still limited. Here, we found that the high level expression of FOXM1 and CCNB1 is closely associated with poor prognosis in HCC patients. And FOXM1 and CCNB1 were overexpressed concomitantly in liver tumor tissues. Knockdown of FOXM1 significantly inhibited the expression levels of CCNB1 in HCC cell lines at both the mRNA and protein levels. Mechanistic studies revealed that FOXM1 binds directly to the promoter region of CCNB1 and regulates the expression levels of the CCNB1 gene in the transcriptional level. Furthermore, the loss of functional and rescue experiments showed that CCNB1 is essential for FOXM1-driven proliferation in HCC cells. In the present study, our results partially explained the dysregulated expression of FOXM1 play an important role in proliferation of human hepatocellular carcinoma cells via transcriptional activation of CCNB1 expression. And it also highlights a FOXM1/CCNB1 axis could be a potential target for the treatment of HCCs.

Staufen1, Kinesin1 and microtubule function in cyclin B1 mRNA transport to the animal polar cytoplasm of zebrafish oocytes.

In zebrafish oocytes, cyclin B1 mRNAs are transported to the animal polar cytoplasm. To elucidate the molecular basis of cyclin B1 mRNA transport, we analyzed zebrafish Staufen1, a protein known to play a central role in mRNA transport to the vegetal pole of Xenopus oocytes. Zebrafish Staufen1 interacts with cyclin B1 mRNA throughout oocyte growth. Both cyclin B1 mRNA and Staufen1 are evenly distributed in the cytoplasm of young oocytes but are co-localized to the animal polar cytoplasm in later stages. Real-time imaging showed that the plus ends of oocyte microtubules are free in the cytoplasm in early stages but anchored to the animal polar cytoplasm in later stages. Transport of cyclin B1 reporter mRNA to the animal polar cytoplasm was inhibited by disruption of microtubules and injection of antibodies against Staufen1 or Kinesin1, a plus-end-directed microtubule motor that interacts with Staufen1, indicating that the transport depends on movement along microtubules toward the plus ends. Reporter mRNAs with an element required for the vegetal localization of vg1 mRNA in Xenopus oocytes were localized to the animal polar cytoplasm in zebrafish oocytes, indicating that the element is functional for animal polar localization in zebrafish oocytes. Our findings suggest that cyclin B1 mRNA-Staufen1 protein complexes are transported toward the animal pole of zebrafish oocytes by the plus-end-directed motor protein Kinesin1 along microtubules and that a common mRNA transport machinery functions in zebrafish and Xenopus oocytes, although its transport direction is opposite due to different organizations of microtubules.

Minute Virus of Mice Inhibits Transcription of the Cyclin B1 Gene during Infection.

Replication of minute virus of mice (MVM) induces a sustained cellular DNA damage response (DDR) which the virus then exploits to prepare the nuclear environment for effective parvovirus takeover. An essential aspect of the MVM-induced DDR is the establishment of a potent premitotic block, which we previously found to be independent of activated p21 and ATR/Chk1 signaling. This arrest, unlike others reported previously, depends upon a significant, specific depletion of cyclin B1 and its encoding RNA, which precludes cyclin B1/CDK1 complex function, thus preventing mitotic entry. We show here that while the stability of cyclin B1 RNA was not affected by MVM infection, the production of nascent cyclin B1 RNA was substantially diminished at late times postinfection. Ectopic expression of NS1 alone did not reduce cyclin B1 expression. MVM infection also reduced the levels of cyclin B1 protein, and RNA levels normally increased in response to DNA-damaging reagents. We demonstrated that at times of reduced cyclin B1 expression during infection, there was a significantly reduced occupancy of RNA polymerase II and the essential mitotic transcription factor FoxM1 on the cyclin B1 gene promoter. Additionally, while total FoxM1 levels remained constant, there was a significant decrease of the phosphorylated, likely active, forms of FoxM1. Targeting of a constitutively active FoxM1 construct or the activation domain of FoxM1 to the cyclin B1 gene promoter via clustered regularly interspaced short palindromic repeats (CRISPR)-enzymatically inactive Cas9 in MVM-infected cells increased both cyclin B1 protein and RNA levels, implicating FoxM1 as a critical target for cyclin B1 inhibition during MVM infection.IMPORTANCE Replication of the parvovirus minute virus of mice (MVM) induces a sustained cellular DNA damage response (DDR) which the virus exploits to prepare the nuclear environment for effective takeover. An essential aspect of the MVM-induced DDR is establishment of a potent premitotic block. This block depends upon a significant, specific depletion of cyclin B1 and its encoding RNA that precludes cyclin B1/CDK1 complex functions necessary for mitotic entry. We show that reduced cyclin B1 expression is controlled primarily at the level of transcription initiation. Additionally, the essential mitotic transcription factor FoxM1 and RNA polymerase II were found to occupy the cyclin B1 gene promoter at reduced levels during infection. Recruiting a constitutively active FoxM1 construct or the activation domain of FoxM1 to the cyclin B1 gene promoter via CRISPR-catalytically inactive Cas9 (dCas9) in MVM-infected cells increased expression of both cyclin B1 protein and RNA, implicating FoxM1 as a critical target mediating MVM-induced cyclin B1 inhibition.

Thromboxane A2 Receptor Inhibition Suppresses Multiple Myeloma Cell Proliferation by Inducing p38/c-Jun N-terminal Kinase (JNK) Mitogen-activated Protein Kinase (MAPK)-mediated G2/M Progression Delay and Cell Apoptosis.

Multiple myeloma (MM) is a plasma cell malignancy without effective therapeutics. Thromboxane A2 (TxA2)/TxA2 receptor (T prostanoid receptor (TP)) modulates the progression of some carcinomas; however, its effects on MM cell proliferation remain unclear. In this study, we evaluated cyclooxygenase (COX) enzymes and downstream prostaglandin profiles in human myeloma cell lines RPMI-8226 and U-266 and analyzed the effects of COX-1/-2 inhibitors SC-560 and NS-398 on MM cell proliferation. Our observations implicate COX-2 as being involved in modulating cell proliferation. We further incubated MM cells with prostaglandin receptor antagonists or agonists and found that only the TP antagonist, SQ29548, suppressed MM cell proliferation. TP silencing and the TP agonist, U46619, further confirmed this finding. Moreover, SQ29548 and TP silencing promoted MM cell G2/M phase delay accompanied by reducing cyclin B1/cyclin-dependent kinase-1 (CDK1) mRNA and protein expression. Notably, cyclin B1 overexpression rescued MM cells from G2/M arrest. We also found that the TP agonist activated JNK and p38 MAPK phosphorylation, and inhibitors of JNK and p38 MAPK depressed U46619-induced proliferation and cyclin B1/CDK1 protein expression. In addition, SQ29548 and TP silencing led to the MM cell apoptotic rate increasing with improving caspase 3 activity. The knockdown of caspase 3 reversed the apoptotic rate. Taken together, our results suggest that TxA2/TP promotes MM cell proliferation by reducing cell delay at G2/M phase via elevating p38 MAPK/JNK-mediated cyclin B1/CDK1 expression and hindering cell apoptosis. The TP inhibitor has potential as a novel agent to target kinase cascades for MM therapy.

A novel quinazoline-based analog induces G2/M cell cycle arrest and apoptosis in human A549 lung cancer cells via a ROS-dependent mechanism.

6-amino-4-(4-phenoxyphenylethylamino)quinazoline (QNZ) is an excellent quinazoline-containing NF-κB inhibitor also acting as a novel anticancer agent. Considering both the medicinal significance of quinazoline scaffold and the tunable functionality of Michael acceptor-centric pharmacophores in the electrophilicity-based prooxidant strategy, we designed a novel QNZ-inspired electrophilic molecule QNZ-A by introducing a Michael acceptor unit at position-6 of quinazoline ring in QNZ. Our results identified QNZ-A as a promising selective cytotoxic agent against A549 cells. QNZ-A, by virtue of its Michael acceptor unit, induced reactive oxygen species (ROS) accumulation associated with collapse of the redox buffering system in A549 cells. This caused up-regulation of p53-inducible p21 and down-regulation of redox sensitive Cdc25C along with Cyclin B1/Cdk1, leading to a G2/M cell cycle arrest and final cell apoptosis. By contrast, QNZ-B, a reduction product of QNZ-A lacking the Michael acceptor unit failed to induce ROS generation and all these cell cycle-related events. In conclusion, this work provided a successful example of designing QNZ-directed anticancer agent by a ROS-promoting strategy and identified QNZ-A as a selective anticancer agent against A549 cells through G2/M cell cycle arrest and apoptosis via a ROS-dependent mechanism.

Novel antitumour indole alkaloid, Jerantinine A, evokes potent G2/M cell cycle arrest targeting microtubules.

Natural products play a pivotal role in the treatment of cancer; identification of compounds such as taxanes and the vinca alkaloids were seminal landmarks in natural product drug discovery. Jerantinine A, a novel Aspidosperma alkaloid isolated from plant species Tabernaemontana corymbosa, was previously reported to possess cytotoxic activity against vincristine-resistant nasopharyngeal carcinoma cells and is therefore an ideal candidate for biological investigation. Furthermore, Tabernaemontana corymbosa, has been placed in the endangered list of threatened species by the International Union for Conservation of Nature thus making it a priority to elucidate the biological activity of this alkaloid. Herein, we report detailed biological evaluation of jerantinine A on various human-derived carcinoma cell lines. Our preliminary screens showed that significant inhibition of cell growth and colony formation accompanied time- and dose-dependent induction of apoptosis in human cancer cell lines after treatment with jerantinine A. Dose-dependent accumulations of cleaved PARP and caspase 3 further confirmed apoptosis. Profound G2/M cell cycle arrest was observed 24 h after treatment in all cell lines. Characteristics of mitotic arrest including inhibition of tubulin polymerisation, microtubule disruption, aneuploidy, and cyclin B1 down-regulation were clearly observed. The potent anti-proliferative, pro-apoptotic, and tubulin-destabilising activities of jerantinine A warrant further development of this molecule as a potential chemotherapeutic agent.

Deoxyelephantopin impairs growth of cervical carcinoma SiHa cells and induces apoptosis by targeting multiple molecular signaling pathways.

Deoxyelephantopin, a sesquiterpene lactone extracted and purified from Elephantopus scaber, has been shown to exhibit antitumor and hepatoprotective activities. The purpose of this study was to investigate the antiproliferative and apoptosis-inducing properties of deoxyelephantopin in SiHa cells and to elucidate the underlying molecular mechanisms. Deoxyelephantopin inhibited growth of SiHa cells and triggered apoptosis. Apoptosis was accompanied by sequential activation of caspases (8, 9, 3, and 7) and reactive oxygen species (ROS) production. Downregulation of antiapoptotic proteins (Bcl2 and Bcl-xL) and upregulation of apoptotic protein (bax) were also detected. Our results demonstrated that deoxyelephantopin-induced G2/M phase arrest was associated with a marked increase in the levels of p53 and p21 and a decrease in phospho-signal transducer and activator of transcription 3 (pSTAT3-Tyr705), cyclin-dependent kinase 1 (cdc2), and cyclin B1. The expression of p-Akt and p-mTOR was downregulated. p-ERK was inhibited while p-JNK and p-p38 was activated on deoxyelephantopin treatment. Our findings provided the first evidence that STAT3/p53/p21 signaling, MAPK pathway, PI3k/Akt/mTOR pathway, caspase cascades, and ROS play critical roles in deoxyelephantopin-induced G2/M phase arrest and apoptosis of SiHa cells.

2-(3-Methoxyphenyl)-5-methyl-1,8-naphthyridin-4(1H)-one (HKL-1) induces G2/M arrest and mitotic catastrophe in human leukemia HL-60 cells.

2-(3-Methoxyphenyl)-5-methyl-1,8-naphthyridin-4(1H)-one (HKL-1), a 2-phenyl-1,8-naphthyridin-4-one (2-PN) derivative, was synthesized and evaluated as an effective antimitotic agent in our laboratory. However, the molecular mechanisms are uncertain. In this study, HKL-1 was demonstrated to induce multipolar spindles, sustain mitotic arrest and generate multinucleated cells, all of which indicate mitotic catastrophe, in human leukemia HL-60 cells. Western blotting showed that HKL-1 induces mitotic catastrophe in HL-60 cells through regulating mitotic phase-specific kinases (down-regulating CDK1, cyclin B1, CENP-E, and aurora B) and regulating the expression of Bcl-2 family proteins (down-regulating Bcl-2 and up-regulating Bax and Bak), followed by caspase-9/-3 cleavage. These findings suggest that HKL-1 appears to exert its cytotoxicity toward HL-60 cells in culture by inducing mitotic catastrophe.

Vector-based miR-15a/16-1 plasmid inhibits colon cancer growth in vivo.

miR-15 (microRNA 15) and miR-16 are frequently deleted or down-regulated in many cancer cell lines and various tumour tissues, suggesting that miR-15a/16-1 plays important roles in tumour progression and might be a method for cancer treatment. We have developed a vector-based plasmid to explore the anti-tumour efficacy of miR-15a/16-1 in colon cancer in vivo. It is proposed that miR-15a and miR-16-1 target cyclin B1 (CCNB1), which associates with several tumorigenic features such as survival and proliferation. The levels of miR-15a and miR-16-1 in colon cancer cells were inversely correlated with CCNB1 expression, and there was consensus between miR-15a/16-1 and CCNB1 mRNA sequences by analysing homology. Vector-based miR-15a/16-1 expression plasmid was constructed and transfected into HCT 116 and SW620 colon cancer cells in vitro. The effects produced on cell viability and angiogenesis were analysed using flow cytometric analysis, colony formation analysis and tube formation analysis. CCNB1 expression down-regulation was checked by Western blotting. Systemic delivery of miR-15a/16-1 plasmids encapsulated in cationic liposome led to a significant inhibition of subcutaneous tumour growth and angiogenesis in tumour tissues, whereas no effects were observed with liposome carrying the non-specific plasmid. In summary, miR-15a/16-1 has been applied in colon cancer treatment in vivo, and resulted in effective colon tumour xenografts growth arrest and angiogenesis decrease. These findings suggest that systemic delivery of vector-based miR-15a/16-1 expression plasmid can be an approach to colon cancer therapy.

Aloe emodin induces G2/M cell cycle arrest and apoptosis via activation of caspase-6 in human colon cancer cells.

Aloe emodin (AE), a natural anthraquinone, is reported to have antiproliferative activity in various cancer cell lines. In this study, we analyzed the molecular mechanisms involved in the growth-inhibitory activity of this hydroxyanthraquinone in colon cancer cell, WiDr. In our observation AE inhibited cell proliferation by arresting the cell cycle at the G2/M phase and inhibiting cyclin B1. AE appreciably induced cell death specifically through the induction of apoptosis and by activating caspases 9/6. Apoptotic execution was found to be solely dependent on caspase-6 rather than caspase-3 or caspase-7. This is the first study indicating that the AE induces apoptosis specifically through the activation of caspase-6.

Human immunodeficiency virus type 1 Vif causes dysfunction of Cdk1 and CyclinB1: implications for cell cycle arrest.

The two major cytopathic factors in human immunodeficiency virus type 1 (HIV-1), the accessory proteins viral infectivity factor (Vif) and viral protein R (Vpr), inhibit cell-cycle progression at the G2 phase of the cell cycle. Although Vpr-induced blockade and the associated T-cell death have been well studied, the molecular mechanism of G2 arrest by Vif remains undefined. To elucidate how Vif induces arrest, we infected synchronized Jurkat T-cells and examined the effect of Vif on the activation of Cdk1 and CyclinB1, the chief cell-cycle factors for the G2 to M phase transition. We found that the characteristic dephosphorylation of an inhibitory phosphate on Cdk1 did not occur in infected cells expressing Vif. In addition, the nuclear translocation of Cdk1 and CyclinB1 was disregulated. Finally, Vif-induced cell cycle arrest was correlated with proviral expression of Vif. Taken together, our results suggest that Vif impairs mitotic entry by interfering with Cdk1-CyclinB1 activation.

Epigallocatechin-3-gallate induces growth inhibition and apoptosis of human anaplastic thyroid carcinoma cells through suppression of EGFR/ERK pathway and cyclin B1/CDK1 complex.

BACKGROUND: Anaplastic thyroid carcinoma (ATC) is one of the most lethal cancers because of its aggressiveness and the lack of efficacious therapy. Epigallocatechin-3-gallate (EGCG), a major catechin in green tea, was shown to possess remarkable therapeutic potential against various types of human cancer cells in in vitro and in vivo models. The aim of this study was to investigate the effect of EGCG on the proliferation and apoptosis of ARO cells--human ATC cells. STUDY DESIGN: Experimental study. METHODS: Human ATC cell line, ARO, was treated with EGCG. Cell viability was assessed by MTT assay. Inhibition of EGFR/MAPK pathway and cell cycle-related proteins by EGCG were measured by Western blot analysis. In addition, cell cycle analysis was measured by flow cytometry. RESULTS: EGCG treatment inhibited the growth of ARO cells in a dose-dependent manner. Furthermore, EGCG suppressed phosphorylation of EGFR, ERK1/2, JNK, and p38. These changes were associated with increased p21 and reduced cyclin B1/CDK1 expression. In addition, EGCG treatment increased the accumulation of sub-G1 cell, activated caspase-3 and cleaved PARP. CONCLUSIONS: Taken together, EGCG inhibits cell proliferation and induces apoptosis via suppression of the EGFR/ERK pathway and cyclin B1/CDK1 complex in ATC cells.

Red mold dioscorea-induced G2/M arrest and apoptosis in human oral cancer cells.

BACKGROUND: Monascus-fermented products are among the most commonly used traditional food supplements. Dioscorea is known to exhibit anticancer properties. In this study the effects of the ethanol extract of red mold dioscorea (RMDE) on cell proliferation, cell cycle and apoptosis in human oral cancer cells were investigated. RESULTS: RMDE exercised growth inhibition on squamous cell carcinoma-25 (SCC-25) cells. RMDE-mediated G2/M phase arrest was associated with the down-regulation of NF-κB, resulting in the inhibition of cyclin B1 and CDK1 expression; this may be the mechanism by which RMDE inhibits cancer cells. Furthermore, the proapoptotic activity of RMDE was revealed by the Annexin V-FITC/PI double-staining assay. In addition, the proapoptotic effect of RMDE was evident by the inhibition of Bax expression in the mitochondria, resulting in the activation of caspase-9 and caspase-3 and subsequent triggering of the mitochondrial apoptotic pathway. RMDE also enhanced caspase-8 activity, indicating the involvement of the death receptor pathway in RMDE-mediated SCC-25 cell apoptosis. CONCLUSION: RMDE treatment inhibited the growth of SCC-25 cells by arresting cell cycle at the G2/M phase and induced apoptosis in a time- and dose-dependent manner. Therefore RMDE may be a good candidate for development as a dietary supplement against oral cancer.

[The CCNB1, HER2, and PKC silencing induced by small interfering RNA decreases a division of different human cancer cells with interfering RNA decreases a different efficiency].

An abnormality in expression of genes encoding proteins responsible for the cell cycle regulation frequently results to a malignant cell transformation and switches the cellular program from differentiation and apoptosis to continuous cell division. To evaluate therapeutic potential resulted from silencing gene expression of key cell circle regulators in different human cancer cells the siRNAs targeted to HER2, protein kinase C (PKC), and cyclin B1 (CCNB1) mRNAs were used. An effective and specific reducing the CCNB1, HER2 or PKC mRNA level was observed through 48 h after the siCycB1, siHER2 or siPKC transfection, respectively. The HER2, PKC, and CCNB1 gene silencing substantially reduced a growth rate of the cell lines, except HL-60, but did not affect the cell death and apoptosis. The best cell division inhibition was induced by the siCycB1 in SK-N-MC cells and by the siPKC in MCF-7 cells. The data obtained suggest the siRNAs selected inhibit the cell division, and the genes investigated may be used as effective targets for curing oncologic diseases.

Knockout of the Placenta Specific 8 Gene Affects the Proliferation and Migration of Human Embryonic Kidney 293T Cell.

Candidate oncogene placenta specific 8 (PLAC8) has been identified to participate in different cellular process and human diseases. However, the effects of PLAC8 on cell proliferation and migration in human kidney cancer (KC) remained unclear. In current study, physiological effects of PLAC8 in immortalized human embryonic kidney cell line (HEK293T) were investigated in vitro. Two PLAC8 knockout (KO) cell lines were established via CRISPR/Cas9-mediated methods combined with fluorescence activated single cell sorting. To classify the characteristic of PLAC8 during cell proliferation and migration in HEK293T, cellular proliferative activity was analyzed by cell counting and colony formation assay. Cell cycle distribution was analyzed by flow cytometry. Cellular motile activity was analyzed by wound-healing and migration assay. Further underlying molecular mechanism was explored via western blot. With the KO cell lines, it was found that PLAC8 KO could decrease cell proliferation. Moreover, the inhibitory effects of PLAC8 KO on cell proliferation were associated with a G2/M arrest in cell cycle progression concomitant with a remarkable inhibition of Cyclin B1 and elevation of Cyclin A. The alteration of cell cycle proteins and E-cadherin might further associate with the enhancement of cell motility. Our study revealed a novel role for PLAC8 in cell proliferation and migration of HEK293T cells, which might shed light on further study of PLAC8 on human KC.

Curcumin Inhibits Proliferation and Epithelial-Mesenchymal Transition in Lens Epithelial Cells through Multiple Pathways.

BACKGROUND: Posterior capsule opacification (PCO), a complication of extracapsular lens extraction surgery that causes visual impairment, is characterized by aberrant proliferation and epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs). Curcumin, exerting inhibitive effects on cell proliferation and EMT in cancer, serves as a possible antidote towards PCO. METHODS: Cellular proliferation of LECs after treatment of curcumin was measured with MTT assay and flow cytometry. The transcriptional and expressional levels of proteins related to proliferation and EMT of LECs were quantified by western blotting and real-time PCR. RESULTS: Curcumin was found to suppress the proliferation of LECs by inducing G2/M arrest via possible inhibition of cell cycle-related proteins including CDK1, cyclin B1, and CDC25C. It had also inactivated proliferation pathways involving ERK1/2 and Akt pathways in LECs. On the other hand, curcumin downregulated the EMT of LECs through blocking the TGF-ß/Smad pathway and interfering Notch pathway which play important roles in PCO. CONCLUSIONS: This study shows that curcumin could suppress the proliferation and EMT in LECs, and it might be a potential therapeutic protection against visual loss induced by PCO.

Synthesis and kinase inhibitory activity of novel substituted indigoids.

The bis-indole indigoids are a promising protein kinase inhibitor scaffold to be further evaluated against the numerous human diseases that imply abnormal regulation of kinases including neurodegenerative disorders. In an effort to identify new pharmacological inhibitors of disease-relevant protein kinases with increased potency and selectivity, we designed, synthesized new 5,7-disubstituted or 6-substituted bis-indole derivatives. On the basis of our previous synthetic work, 22 selected compounds were tested on CDK1/cyclin B, CDK5/p25, DYRK1A, CK1, and GSK-3alpha/beta kinases, five kinases involved in Alzheimer's disease. Some of them were also evaluated for their cytotoxic and antiproliferative activities. 6-Nitro-3'-N-oxime-indirubin and 5-amino-3'-N-oxime-indirubin derivatives exhibited inhibitory activity in a submicromolar range against CDK1/cyclin B (0.18 and 0.1 microM, respectively), CK1 (0.6 microM and 0.13 microM) and GSK3 (0.04 microM and 0.36 microM).

Molecular mechanism of Forkhead box M1 inhibition by thiostrepton in breast cancer cells.

Breast cancer is the most common type of malignancies in women worldwide, and genotoxic chemotherapeutic drugs are effective by causing DNA damage in cancer cells. However, >90% of patients with metastatic cancer are resistant to chemotherapy. The Forkhead box M1 (FOXM1) transcription factor plays a pivotal role in the resistance of breast cancer cells to chemotherapy by promoting DNA damage repair following genotoxic drug treatment. The aim of the present study was to investigate the inhibition of the FOXM1 protein by thiostrepton, a natural antibiotic produced by the Streptomyces species. Experimental studies were designed to examine the effectiveness of thiostrepton in downregulating FOXM1 mRNA expression and activity, leading to senescence and apoptosis of breast cancer cells. The cytotoxicity of thiostrepton in breast cancer was determined using cell viability assay. Additionally, thiostrepton treatment decreased the mRNA expression of cyclin B1 (CCNB1), a downstream target of FOXM1. The present results indicated that thiostrepton inhibited FOXM1 mRNA expression and its effect on CCNB1. Molecular dynamic simulations were performed to study the interactions between FOXM1­DNA and thiostrepton after molecular docking. The results revealed that the possible mechanism underlying the inhibitory effect of thiostrepton on FOXM1 function was by forming a tight complex with the DNA and FOXM1 via its binding domain. Collectively, these results indicated that thiostrepton is a specific and direct inhibitor of the FOXM1 protein in breast cancer. The findings of the present study may lead to the development of novel therapeutic strategies for breast cancer and help overcome resistance to conventional chemotherapeutic drugs.