p53 regulates nuclear GSK-3 levels through miR-34-mediated Axin2 suppression in colorectal cancer cells

p53 is a bona fide tumor suppressor gene whose loss of function marks the most common genetic alteration in human malignancy. Although the causal link between loss of p53 function and tumorigenesis has been clearly demonstrated, the mechanistic links by which loss of p53 potentiates oncogenic signaling are not fully understood. Recent evidence indicates that the microRNA-34 (miR-34) family, a transcriptional target of the p53, directly suppresses a set of canonical Wnt genes and Snail, resulting in p53-mediated suppression of Wnt signaling and the EMT process. In this study, we report that p53 regulates GSK-3β nuclear localization via miR-34-mediated suppression of Axin2 in colorectal cancer. Exogenous miR-34a decreases Axin2 UTR-reporter activity through multiple binding sites within the 5′ and 3′ UTR of Axin2. Suppression of Axin2 by p53 or miR-34 increases nuclear GSK-3β abundance and leads to decreased Snail expression in colorectal cancer cells. Conversely, expression of the non-coding UTR of Axin2 causes depletion of endogenous miR-34 via the miR-sponge effect together with increased Axin2 function, supporting that the RNA-RNA interactions with Axin2 transcripts act as an endogenous decoy for miR-34. Further, RNA transcripts of miR-34 target were correlated with Axin2 in clinical data set of colorectal cancer patients. Although the biological relevance of nuclear GSK-3 level has not been fully studied, our results demonstrate that the tumor suppressor p53/miR-34 axis plays a role in regulating nuclear GSK-3 levels and Wnt signaling through the non-coding UTR of Axin2 in colorectal cancer.ope

Real-time quantitative monitoring of specific peptide cleavage by a proteinase for cancer diagnosis

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Anchored proteinase-targetable optomagnetic nanoprobes for molecular imaging of invasive cancer cells

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Effects of artemisinin and its derivatives on growth inhibition and apoptosis of oral cancer cells

BACKGROUND: Artemisinin is of special biological interest because of its outstanding antimalarial activity. Recently, it was reported that artemisinin has antitumor activity. Its derivatives, artesunate, arteether, and artemeter, also have antitumor activity against melanoma, breast, ovarian, prostate, CNS, and renal cancer cell lines. Recently, monomer, dimer, and trimer derivatives were synthesized from deoxoartemisinin, and the dimers and the trimers were found to have much more potent antitumor activity than the monomers. METHODS: We evaluated the antitumor activity of artemisinin and its various derivatives (dihydroartemisinin, dihydroartemisinin 12-benzoate, 12-(2'-hydroxyethyl) deoxoartemisinin, 12-(2'-ethylthio) deoxoartemisinin dimer, deoxoartemisinin trimer) in comparison with paclitaxel (Taxol), 5-fluorouracil (5-FU), cisplatin in vitro. RESULTS: In this study, the deoxoartemisinin trimer had the most potent antitumor effect (IC(50) = 6.0 microM), even better than paclitaxel (IC(50) = 13.1 microM), on oral cancer cell line (YD-10B). In addition, it induced apoptosis through a caspase-3-dependent mechanism. CONCLUSION: The deoxoartemisinin trimer was found to have greater antitumor effect on tumor cells than other commonly used chemotherapeutic drugs, such as 5-FU, cisplatin, and paclitaxel. Furthermore, the ability of artemisinin and its derivatives to induce apoptosis highlights their potential as chemotherapeutic agents, for many anticancer drugs achieve their antitumor effects by inducing apoptosis in tumor cells.ope

p53 and microRNA-34 are suppressors of canonical Wnt signaling

Although loss of p53 function and activation of canonical Wnt signaling cascades are frequently coupled in cancer, the links between these two pathways remain unclear. We report that p53 transactivated microRNA-34 (miR-34), which consequently suppressed the transcriptional activity of β-catenin-T cell factor and lymphoid enhancer factor (TCF/LEF) complexes by targeting the untranslated regions (UTRs) of a set of conserved targets in a network of genes encoding elements of the Wnt pathway. Loss of p53 function increased canonical Wnt signaling by alleviating miR-34-specific interactions with target UTRs, and miR-34 depletion relieved p53-mediated Wnt repression. Gene expression signatures reflecting the status of β-catenin-TCF/LEF transcriptional activity in breast cancer and pediatric neuroblastoma patients were correlated with p53 and miR-34 functional status. Loss of p53 or miR-34 contributed to neoplastic progression by triggering the Wnt-dependent, tissue-invasive activity of colorectal cancer cells. Further, during development, miR-34 interactions with the β-catenin UTR affected Xenopus body axis polarity and the expression of Wnt-dependent patterning genes. These data provide insight into the mechanisms by which a p53-miR-34 network restrains canonical Wnt signaling cascades in developing organisms and human cancer.ope

In vitro mesenchymal stem cell culture using calcium phosphate glass scaffold

The purpose of this study was to evaluate the cell affinity of calcium phosphate glass scaffold in the system of CaO-CaF2-P2O5-MgO-ZnO, which is already reported that promoted the bone-like tissue formation in vitro and formed new bone in Sprague-Dawley rats. We prepared calcium phosphate glass saffolds with three-dimensionally interconnected pores of 200~500 µm. Commercial HA scaffold was employed as a control in this study. Bone marrow cells were collected from the healthy human donors and cultured within the prepared scaffolds. After 2, 4, 6, and 8 weeks, hMSCs/scaffold were fixed and stained with hematoxylin and eosin. hMSCs were continuously proliferated both in the experimental and control groups at every incubation period. The number of cells was higher in the experimental group than that of the control group, however, there was no significant difference (p>0.05). Extracellular matrices could be observed at the 2nd and 4th days in the experimental and control groups, respectively. The extracellular matrices were more abundant in the experimental group at all periods. The prepared calcium phosphate glass scaffolds are expected effective in bone tissue engineering.ope

A platform technique for growth factor delivery with novel mode of action

Though growth factors allow tissue regeneration, the trade-off between their effectiveness and adverse effects limits clinical application. The key issues in current growth factor therapy largely derive from initial burst pharmacokinetics, rapid clearance, and proteolytic cleavage resulting in clinical ineffectiveness and diverse complications. While a number of studies have focused on the development of carriers, issues arising from soluble growth factor remain. In this study, we report a prodrug of growth factors constituting a novel mode of action (MoA). To mimic endogenous protein processing in cells, we developed a recombinant BMP-2 polypeptide based on a protein transduction domain (PTD) to transduce the protein into cells followed by furin-mediated protein cleavage and secretion of active growth factor. As proof of concept, a few micrograms scale of PTD-BMP-2 polypeptide sufficed to induce bone regeneration in vivo. As a simple platform, our technique can easily be extended to delivery of BMP-7 and DKK-1 as therapeutics for TGF-β and canonical Wnt signaling, respectively, to suppress the epithelial–mesenchymal transition (EMT), which constitutes a fundamental biological mechanism of many diseases. This technique largely overcomes the limitations of current soluble growth factors and opens the door to next generation growth factor therapeutics.ope