naphthoquinones and benzyloxycarbonylleucyl-leucyl-leucine-aldehyde

Ovarian cancer is a disease with the highest mortality in gynecologic malignancies. Activation of STAT3 pathway is well known to be associated with tumor progression and metastasis in a number of cancers, including ovarian cancer. Therefore, STAT3 may be an ideal target for ovarian cancer treatment.. The present study aims to determine the antitumor activity of STAT3 inhibitor Napabucasin as a single agent or in combination with proteasome inhibitor MG-132 in ovarian cancer cells.. MTT was performed to determine the anti-proliferative effect of Napabucasin on ovarian cancer SKOV-3 cells. The involved anti-tumor mechanism was explored by flow cytometry, qRTPCR and western blot. MDC staining and tandem mRFP-GFP-LC3 fluorescence microscopy were used to analyze the autophagy-inducing capability of Napabucasin with or without MG-132. The combinational anticancer effect of Napabucasin and MG-132 was evaluated according to Chou and Talalay's method (1984).. Napabucasin showed obvious tumor-inhibitory effects against SKOV-3 cells. Treatment by Napabucasin arrested cell cycle progression in G2/M phase. Mechanistically, elevated expression of p21 may contribute to the blockade of the cell cycle. Moreover, we demonstrated that Napabucasin induced autophagy in SKOV-3 cells by using various assays, including MDC staining, autophagic flux examination, and detection of the autophagy markers. In addition, a combination of Napabucaisin with MG-132 exhibited a significant synergistic anti-proliferative effect, probably by inducing apoptosis through a mitochondria-dependent pathway. The two compounds induced pro-survival autophagies, and co-treatment with autophagy inhibiter might further enhance their antitumor effects.. Napabucasin alone or in combination with MG-132 might be promising treatment strategy for ovarian cancer patients.

Topics: Apoptosis; Benzofurans; Carcinoma, Ovarian Epithelial; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cysteine Proteinase Inhibitors; Drug Synergism; Female; G2 Phase Cell Cycle Checkpoints; Humans; Leupeptins; Naphthoquinones; Ovarian Neoplasms; Proteasome Endopeptidase Complex; Proteasome Inhibitors; STAT3 Transcription Factor

Hematopoietic gene delivery, such as hematopoietic stem/progenitor cells (HSPCs), is a promising treatment for both inherited and acquired diseases, such as hemophilia. Recently, a combined strategy to achieve more than 90% transduction efficiency was documented using recombinant adeno-associated virus serotype 6 (rAAV6) vectors. However, the mechanisms of enhanced vector transduction efficiency in hematopoietic cells are largely unknown. In this manuscript, we first reported that proteasome inhibitors, which are well-known to facilitate rAAV intracellular trafficking in various cell types, are not effective in hematopoietic cells. From the screening of small molecules derived from traditional Chinese medicine, we demonstrated that shikonin, a potential reactive oxygen species (ROS) generator, significantly increased the in vitro and ex vivo transgene expression mediated by rAAV6 vectors in hematopoietic cells, including human cord blood-derived CD34 + HSPCs. Shikonin mainly targeted vector intracellular trafficking, instead of host cell entry or endonuclear single to double strand vector DNA transition, in a vector serotype-dependent manner. Moreover, a ROS scavenger completely prevented the capability of shikonin to enhance rAAV6 vector-mediated transgene expression. Taken together, these studies expand our understanding of rAAV6-mediated transduction in hematopoietic cells and are informative for improving rAAV6-based treatment of blood diseases.

Topics: Cells, Cultured; Dependovirus; Genetic Vectors; Hematopoietic Stem Cells; Humans; Leupeptins; Medicine, Chinese Traditional; Naphthoquinones; Parvovirinae; Proteasome Endopeptidase Complex; Reactive Oxygen Species; Transduction, Genetic

Pin1, a conserved eukaryotic peptidyl-prolyl cis/trans isomerase, has important roles in cellular regulation. Because of its activity to switch the conformation of peptidyl-proline bonds in polypeptide chains, Pin1 operates as a binary switch, often in fate-determining pathways. Pin1 activity is usually controlled by substrate phosphorylation, but how Pin1 switches protein fates has been unclear. Here we show that Pin1 controls the degree of substrate ubiquitylation and thereby protein functions. We found that yeast Pin1 (Ess1) is essential for viability because it controls the NF-kappaB-related Spt23 transcription factor involved in unsaturated fatty-acid synthesis. High Pin1 activity results in low ubiquitylation of Spt23, which triggers Spt23 precursor processing and hence transcription factor activation. By contrast, decreased Pin1 activity leads to robust Spt23 polyubiquitylation and subsequent proteasomal degradation. Inhibition of Pin1 in mammalian cells changes the ubiquitylation status of the tumour suppressor protein p53 from oligoubiquitylation, which is known to trigger nuclear export, to polyubiquitylation, which causes nuclear p53 degradation. This suggests that the Pin1 activity is often translated into a fate-determining ubiquitylation switch, and that Pin1 may affect the degree of substrate ubiquitylation in other pathways as well.

Topics: Active Transport, Cell Nucleus; Cell Line, Tumor; Cell Nucleus; Enzyme Inhibitors; Humans; Immunoblotting; Immunoprecipitation; Leupeptins; Membrane Proteins; Microscopy, Fluorescence; Naphthoquinones; NIMA-Interacting Peptidylprolyl Isomerase; Peptidylprolyl Isomerase; Phosphorylation; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Protein Binding; Saccharomyces cerevisiae Proteins; Substrate Specificity; Trans-Activators; Transcription Factors; Tumor Suppressor Protein p53; Ubiquitin; Ubiquitination

The serine/threonine kinase Raf-1 is a major regulator of the mitogen activated protein kinase (MAPK) pathway, which has been associated with the progression of prostate cancer to the more advanced and androgen-independent disease. Cdc25A phosphatase has been implicated in the regulation of Raf-1 and the MAPK pathway.. We used a novel and potent Cdc25A inhibitor, 2,3-bis-[2-hydroxyethylsulfonyl]-[1,4] naphthoquinone (NSC 95397), and its congener (2-mercaptoethanol)-3-methyl-1, 4-naphthoquinone (NSC 672121) to study the role of Cdc25A on the MAPK pathway in human prostate cancer cells.. We found Raf-1 physically interacted with Cdc25A in PC-3 and LNCap cells and inhibitors of Cdc25A induced both extracellular signal-regulated kinase (Erk) activation and Raf-1 tyrosine phosphorylation. NSC 95397 attenuated Cdc25A and Raf-1 interactions due to accelerated degradation of Cdc25A, which was mediated by proteasome degradation. The MAPK kinase (MEK) inhibitor U0126 completely inhibited Erk activation by NSC 95397 and NSC 672121.. These results indicate Cdc25A phosphatase regulates Raf-1/MEK/Erk kinase activation in human prostate cancer cells.

Topics: Blotting, Western; Butadienes; cdc25 Phosphatases; Cell Line, Tumor; Enzyme Inhibitors; Humans; Leupeptins; Male; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Naphthoquinones; Nitriles; Phosphorylation; Prostatic Neoplasms; Proto-Oncogene Proteins c-raf