Recent studies identified a short peptide motif that serves as a docking site for cyclin͞cyclin-dependent kinase (cdk) 2 complexes . Peptides containing this motif block the phosphorylation of substrates by cyclin A͞cdk2 or cyclin E͞cdk2. Here we report that cell membrane-permeable forms of such peptides preferentially induced transformed cells to undergo apoptosis relative to nontransformed cells. Deregulation of E2F family transcription factors is a common event during transformation and was sufficient to sensitize cells to the cyclin͞cdk2 inhibitory peptides. These results suggest that deregulation of E2F and inhibition of cdk2 are synthetically lethal and provide a rationale for the development of cdk2 antagonists as antineoplastic agents.Certain molecular pathways frequently are altered during human carcinogenesis. Therefore one approach to treating cancer, while minimizing host toxicity, would be to develop drugs that preferentially kill cells in which such pathways are altered.An example of a molecular pathway that is recurrently altered in cancer involves the retinoblastoma tumor suppressor protein (pRB) (1-3). Many tumors lack a wild-type RB-1 allele, thus depriving them of pRB. Furthermore, pRB is negatively regulated by cyclin-dependent kinases (cdks). These cdks are, in turn, negatively regulated by certain cdk inhibitors and positively regulated by certain cyclins. These upstream pRB regulators frequently are altered in tumors that retain a wild-type RB-1 allele. Thus, functional inactivation of pRB, a known inhibitor of cell growth, may be a necessary step in human carcinogenesis.Members of the E2F cell-cycle regulatory transcription factor family are critical downstream targets of pRB. Binding to pRB converts E2F from a transcriptional activator to a potent transcriptional repressor. Consequently, E2F-responsive genes are activated in cancer cells because of loss of pRB͞E2F repressor complexes and liberation of free, transcriptionally active E2F. Of note, at least some E2F family members, including E2F1, are themselves transcribed from E2F-responsive promoters (4-7). Thus, pathological activation of E2F responsive genes can establish a positive feedback loop. Paradoxically, forced activation of E2F-responsive genes, such as through the overproduction of E2F1, can induce both cellular proliferation and cell death (apoptosis) (8-11).E2F family members bind to DNA as heterodimers with members of the DP family. The DNA-binding capability of some of these heterodimers is negatively regulated by cyclin A͞cdk2 (12-15). For example, E2F1, E2F2, and E2F3 each contain a short, collinear cyclin A͞cdk2 binding motif that is required for the timely neutralization of E2F DNA-binding capability as cells traverse and prepare to exit S phase (13,16,17). Mutation of this motif in E2F1 enhances its ability to induce apoptosis (13). In summary, E2F is negatively regulated by both pRB and cyclin A͞cdk2. We therefore reasoned that pharmacologic inhibition of cyclin A͞cdk2 might preferentially kill cells in whic...

Purpose: p53 is frequently expressed but rarely mutated in Hodgkin and Reed-Sternberg (HRS) cells of Hodgkin's lymphoma (HL). p53 protein levels are regulated by murine double minute 2 (MDM2) through a well-established autoregulatory feedback loop. In this study, we investigated the effects of nutlin-3A, a recently developed small molecule that antagonizes MDM2 and disrupts thep53-MDM2 interaction, onp53-dependent cellcycle arrest andapoptosis incultured HRS cells. Experimental Design: HL cell lines carrying wild-type (wt) or mutated p53 gene were treated with the potent MDM2 inhibitor nutlin-3A or a 150-fold less active enantiomer, nutlin-3B. Results: We show that nutlin-3A, but not nutlin-3B, stabilizes p53 in cultured HRS cells carrying wt p53 gene resulting in p53-dependent cell cycle arrest and apoptosis. Cell cycle arrest was associated with up-regulation of the cyclin-dependent kinase inhibitor p21. Nutlin-3Aî nduced apoptotic cell death was accompanied by Bax and Puma up-regulation and caspase-3 cleavage and was abrogated, in part, by inhibition of caspase-9 and caspase-3 activity. By contrast, no effects on cell cycle or apoptosis were found in HL cell lines harboring mutated p53 gene. Furthermore, combined treatment with nutlin-3A and doxorubicin revealed enhanced cytotoxicity in HRS cells with wt p53 gene. Blocking of nuclear export by leptomycin B, or inhibition of proteasome by MG132, stabilized p53 at a level comparable with that of nutlin-3A treatment in HRS cells with wt p53. Conclusions: These data suggest that nutlin-3A stabilized p53 by preventing MDM2-mediated p53 degradation in HRS cells. wt p53 stabilization and activation by nutlin-3A may be a novel therapeutic approach for patients with HL.

Tic disorders (TD) are a group neuropsychiatric disorders with childhood onset characterized by tics, i.e. repetitive, sudden, and involuntary movements or vocalizations; and Tourette syndrome (TS) is the most severe form of TD. Their clinical manifestations are diverse; and are often associated with various psychopathological and/ or behavioral comorbidities, including attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety, depression, and sleep disorders. Individual severity and response to treatment are highly variable, and there are some refractory cases, which are less responsive to conventional TD treatment. TD/TS are also common in the Chinese pediatric population. To help improve the understanding of TD for pediatricians and other health professionals, and to improve its diagnosis and treatment in China, the Chinese Child Neurology Society (CCNS) has developed an Expert Consensus on Diagnosis and Treatment of TD in China, which is based on our clinical experience and the availability therapeutic avenues. It is focused on clinical diagnosis and evaluation of TD and its comorbidities, psychological and educational intervention, nonpharmacological therapy, pharmacological treatment, including traditional Chinese medicine and acupuncture, as well as prognosis in children with TD in China. A summary of the current status of TD and up-to-date diagnosis and treatment recommendations for TD in China is presented here.

Liver fibrosis is a chronic disorder that is characterized by an alteration of the balance between fibrogenesis and fibrinolysis, which results in accumulation of excessive amounts of extracellular matrix (ECM) and distortion of the normal liver architecture. The activation and transformation of quiescent hepatic stellate cells (HSCs) into myofibroblast-like cells constitute a major mechanism for the increased production of ECM in the liver. The nuclear receptor farnesoid X receptor (FXR) shows potent antifibrotic activity in HSCs and protects animals in rodent models of liver fibrosis. However, the detailed mechanism remains incompletely understood. In this study, we report that treatment with 3-, a synthetic FXR ligand, led to up-regulation of microRNA-29a (miR-29a) in HSCs isolated from wild-type mice, rats, and humans but not from FXR(Ϫ/Ϫ) mice. miR-29a seems to play an inhibitory role in the regulation of ECM production because of the following: 1) transfection of HSCs with miR-29a mimic resulted in drastic downregulation of the mRNA expression of several genes that encode ECM proteins; and 2) miR-29a significantly inhibited the expression of a reporter expression plasmid that contains the 3Ј-untranslated region of the corresponding ECM genes. Our results suggest that miR-29a is a FXR target gene because miR-29a promoter activity was significantly increased by pharmacologic or genetic activation of FXR. Functional analysis of human miR-29a promoter identified an imperfect inverted repeat spaced by one nucleotide DNA motif, inverted repeat-1 (5Ј-AGGTCAcAGACCT-3Ј), as a likely FXR-responsive element that is involved in miR-29a regulation. Our study uncovers a new mechanism by which FXR negatively regulates the expression of ECM in HSCs.

Altered expression of miR-29b is implicated in the pathogenesis and progression of liver fibrosis. We and others previously demonstrated that miR-29b down-regulates the expression of several extracellular-matrix (ECM) genes including Col 1A1, Col 3A1 and Elastin via directly targeting their 3′-UTRs. However, whether or not miR-29b plays a role in the post-translational regulation of ECM biosynthesis has not been reported. Heat shock protein 47 (HSP47) and lysyl oxidase (LOX) are known to be essential for ECM maturation. In this study we have demonstrated that expression of HSP47 and LOX was significantly up-regulated in culture-activated primary rat hepatic stellate cells (HSCs), TGF-β stimulated LX-2 cells and liver tissue of CCl4-treated mice, which was accompanied by a decrease of miR-29b level. In addition, over-expression of miR-29b in LX-2 cells resulted in significant inhibition on HSP47 and LOX expression. Mechanistically, miR-29b inhibited the expression of a reporter gene that contains the respective full-length 3′-UTR from HSP47 and LOX gene, and this inhibitory effect was abolished by the deletion of a putative miR-29b targeting sequence from the 3′-UTRs. Transfection of LX-2 cells with miR-29b led to abnormal collagen structure as shown by electron-microscopy, presumably through down-regulation of the expression of molecules involved in ECM maturation including HSP47 and LOX. These results demonstrated that miR-29b is involved in regulating the post-translational processing of ECM and fibril formation.

In this study, transparent ZnS ceramics were hot pressed from precipitated wurtzite nanopowders. Influences of sintering temperature on wurtzite‐to‐sphalerite phase transition and densification behavior have been investigated. Maximum sphalerite phase content and highest densification were simultaneously obtained in the sample hot pressed at 900°C with uniaxial pressure of 250 MPa for 2 h, which accounts for the highest transmittance above 55% and 70% in the range 2–5 μm and 5–13 μm, respectively. Preferred orientation of wurtzite grains in [002] direction paralleled to the press direction was also observed, which is supposed to be benefit to transmittance by reducing birefraction and second‐phase scattering. Furthermore, second‐phase scattering caused by wurtzite grains has been investigated. It is found that fine grains are conducive to hot‐pressed ZnS ceramics with high transmittance, especially in the short‐wavelength range.

The mixed trialkyltin derivatives, obtained by introducing different alkyls on tin atom, have provoked more interests for their multi-bioactivities. And it has become an important branch of organotin chemistry. A series of novel mixed methyldicyclohexyltin carboxylates were synthesized and characterized through IR, 'H, 119 Sn, 13 C NMR and MS. The results showed that the structures of the compounds are dependent on the steric and electronic effects of the carbonyl group. The preliminary pesticidal tests show that all the compounds have excellent acaricidal activity and many of them also exhibit good insecticidal, fungicidal and herbicidal activities. The biological activities are mainly determined by the methyl and cyclohexyl on tin atom and has close relations with the anion group.

Nature has generously offered life-saving therapies to mankind by providing evolutionarily optimized drug-like entities in the form of natural products. These splendid gifts of nature have served as most suitable candidates for anti-cancer drug discovery due to their pleiotropic activity on target molecules. This review aims to provide an update on the natural sources and bioactivities of such gifts from nature, salvianolic acid A & B, which are major bioactive constituents of a traditional Chinses medicinal herb, Salvia miltiorrhiza. Salvianolic acid A & B have been reported to owe anti-cancer, anti-inflammatory and cardioprotective activities. Currently salvianolic acids have been emerged as potent anti-cancer molecules. Salvianolic acid A & B fight cancer progression by prompting apoptosis, halting cell cycle and adjourning metastasis by targeting multiple deregulated signaling networks of cancer. Moreover, salvianolic acid A & B display potency towards sensitizing cancer cells to chemo-drugs. The review purposes that salvianolic acid A & B supply a novel opportunity for drug discovery but further experimentation is mandatory to embellish the knowledge of their pharmacological usage and to access their toxicological limits in order to establish these compounds as potential multitarget future drugs.