Jianfeng Cai

Resveratrol Inhibits Invasion and Metastasis of Colorectal Cancer Cells via MALAT1 Mediated Wnt/β-Catenin Signal Pathway

Resveratrol, extracted from Chinese herbal medicine Polygonum cuspidatum, is known to inhibit invasion and metastasis of human colorectal cancer (CRC), in which long non-coding Metastasis Associated Lung Adenocarcinoma Transcript 1 (RNA-MALAT1) also plays an important role. Using MALAT1 lentiviral shRNA and over-expression constructs in CRC derived cell lines, LoVo and HCT116, we demonstrated that the anti-tumor effects of resveratrol on CRC are through inhibiting Wnt/β-catenin signaling, thus the expression of its target genes such as c-Myc, MMP-7, as well as the expression of MALAT1. In detail, resveratrol down-regulates MALAT1, resulting in decreased nuclear localization of β-catenin thus attenuated Wnt/β-catenin signaling, which leads to the inhibition of CRC invasion and metastasis. This finding of ours surely provides important pre-clinical evidence supporting future use of resveratrol in prevention and treatment of CRC.

High Blood caffeine levels in MCI linked to lack of progression to dementia.

Although both human epidemiologic and animal model studies have suggested that caffeine/coffee protects against Alzheimers disease, direct human evidence for this premise has been lacking. In the present case-control study, two separate cohorts consisting of 124 total individuals (65-88 years old) were cognitively assessed and a blood sample taken for caffeine/biomarker analysis. Subjects were then monitored for cognitive status over the ensuing 2-4 year period to determine the extent to which initial plasma caffeine/biomarkers levels would be predictive of changes in cognitive status. Plasma caffeine levels at study onset were substantially lower (-51%) in mild cognitive impairment (MCI) subjects who later progressed to dementia (MCI→DEM) compared to levels in stable MCI subjects (MCI→MCI). Moreover, none of the MCI→DEM subjects had initial blood caffeine levels that were above a critical level of 1200 ng/ml, while half of stable MCI→MCI subjects had blood caffeine levels higher than that critical level. Thus, plasma caffeine levels greater than 1200 ng/ml (≈6 μM) in MCI subjects were associated with no conversion to dementia during the ensuing 2-4 year follow-up period. Among the 11 cytokines measured in plasma, three of them (GCSF, IL-10, and IL-6) were decreased in MCI→DEM subjects, but not in stable MCI→MCI subjects with high plasma caffeine levels. Coffee would appear to be the major or perhaps only source of caffeine for such stable MCI patients. This case-control study provides the first direct evidence that caffeine/coffee intake is associated with a reduced risk of dementia or delayed onset, particularly for those who already have MCI.

Improving the Stability of Aptamers by Chemical Modification

Ever since the invention of SELEX (systematic evolution of ligands by exponential enrichment), there has been rapid development for aptamers over the last two decades, making them a promising approach in therapeutic applications as either drug candidates or diagnostic tools. For therapeutic purposes, a durable performance of aptamers in biofluids is required, which is, however, hampered by the lack of stability of most aptamers. Not only are the nucleic acid aptamers susceptible to nucleases, the peptide aptamers are also subjective to degradation by proteases. With the advancement of chemical biology, numerous attempts have been made to overcome this obstacle, many resulting in significant improvements in stability. In this review, chemical modifications to increase the stability of three main types of aptamers, DNA, RNA and peptide are comprehensively summarized. For nucleic acid aptamers, development of modified SELEX coupled with mutated polymerase is discussed, which is adaptive to a number of modifications in aptamers and in a large extent facilitates the research of aptamer-modifications. For peptide aptamers, approaches in molecular biology with introduction of stabilizing protein as well as the switch of scaffold protein are included, which may represent a future direction of chemical conjugations to aptamers.

Lipo-γ-AApeptides as a New Class of Potent and Broad-Spectrum Antimicrobial Agents

There is increasing demand to develop antimicrobial peptides (AMPs) as next generation antibiotic agents, as they have the potential to circumvent emerging drug resistance against conventional antibiotic treatments. Non-natural antimicrobial peptidomimetics are an ideal example of this, as they have significant potency and in vivo stability. Here we report for the first time the design of lipidated γ-AApeptides as antimicrobial agents. These lipo-γ-AApeptides show potent broad-spectrum activities against fungi and a series of Gram-positive and Gram-negative bacteria, including clinically relevant pathogens that are resistant to most antibiotics. We have analyzed their structure-function relationship and antimicrobial mechanisms using membrane depolarization and fluorescent microscopy assays. Introduction of unsaturated lipid chain significantly decreases hemolytic activity and thereby increases the selectivity. Furthermore, a representative lipo-γ-AApeptide did not induce drug resistance in S. aureus, even after 17 rounds of passaging. These results suggest that the lipo-γ-AApeptides have bactericidal mechanisms analogous to those of AMPs and have strong potential as a new class of novel antibiotic therapeutics.

Anti-tumor Activity and Apoptosis-regulation Mechanisms of Bufalin in Various Cancers: New Hope for Cancer Patients

The induction of apoptosis in target cells is a key mechanism for most anti-tumor therapies. Bufalin is a cardiotonic steroid that has the potential to induce differentiation and apoptosis of tumor cells. Research on bufalin has so far mainly involved leukemia, prostate cancer, gastric cancer and liver cancer, and has been confined to in vitro studies. The bufadienolides bufalin and cinobufagin have been shown to induce apoptosis in a wide spectrum of cancer cell. The present article reviews the anticancer effects of bufalin. It induces apoptosis of lung cancer cells via the PI3K/Akt pathway and also suppressed the proliferation of human non-small cell lung cancer A549 cell line in a time and dose dependent manner. Bufalin, bufotalin and gamabufotalin, key bufadienolides, significantly sensitize human breast cancer cells with differing ER-alpha status to apoptosis induction by the TNF-related apoptosis-inducing ligand (TRAIL). In addition, bufadienolides induce prostate cancer cell apoptosis more significantly than that in breast epithelial cell lines. Similar effects have been observed with hepatocellular carcinoma (HCC) but the detailed molecular mechanisms of inducing apoptosis in this case are still unclear. Bufalin exerts profound effects on leukemia therapy in vitro. Results of multiple studies indicate that bufalin has marked anti-tumor activities through its ability to induce apoptosis. Large-scale randomized, double-blind, placebo or positive drug parallel controlled studies are now required to confirm the efficacy and apoptosis-inducing potential of bufalin in various cancers in the cliniucal setting.

Resveratrol suppresses epithelial-to-mesenchymal transition in colorectal cancer through TGF-β1/Smads signaling pathway mediated Snail/E-cadherin expression

BackgroundResveratrol extracted from grape has been an ideal alternative drug in the therapy of different cancers including colorectal cancer (CRC). Since the underlying mechanisms of resveratrol on the invasion and metastasis of CRC have not been fully elucidated, and epithelial-to-mesenchymal transition (EMT) is a key process associated with the progression of CRC, here we aimed to investigate the potential mechanism of resveratrol on the inhibition of TGF-β1-induced EMT in CRC LoVo cells.MethodsWe investigated the anticancer effect of resveratrol against LoVo cells in vitro and in vivo. In vivo, the impact of resveratrol on invasion and metastasis was investigated by mice tail vein injection model and mice orthotopic transplantation tumor model. In vivo imaging was applied to observe the lungs metastases, and hemaoxylin-eosin (HE) staining was used to evaluate metastatic lesions. In vitro, impact of resveratrol on the migration and invasion of LoVo cells was evaluated by transwell assay. Inhibition effect of resveratrol on TGF-β-induced EMT was examined by morphological observation. Epithelial phenotype marker E-cadherin and mesenchymal phenotype marker Vimentin were detected by western blot and immunofluorescence. Promoter activity of E-cadherin was measured using a dual-luciferase assay kit. mRNA expression of Snail and E-cadherin was measured by RT-PCR.ResultsWe demonstrated that, resveratrol inhibited the lung metastases of LoVo cells in vivo. In addition, resveratrol reduced the rate of lung metastases and hepatic metastases in mice orthotopic transplantation. In vitro, TGF-β1-induced EMT promoted the invasion and metastasis of CRC, reduced the E-cadherin expression and elevated the Vimentin expression, and activated the TGF-β1/Smads signaling pathway. But resveratrol could inhibit the invasive and migratory ability of LoVo cells in a concentration-dependent manner, increase the expression of E-cadherin, repress the expression of Vimentin, as well as the inhibition of TGF-β1/Smads signaling pathway. Meanwhile, resveratrol reduced the level of EMT-inducing transcription factors Snail and the transcription of E-cadherin during the initiation of TGF-β1-induced EMT.ConclusionsOur new findings provided evidence that, resveratrol could inhibit EMT in CRC through TGF-β1/Smads signaling pathway mediated Snail/E-cadherin expression, and this might the potential mechanism of resveratrol on the inhibition of invasion and metastases in CRC.

Identification of γ-AApeptides with potent and broad-spectrum antimicrobial activity

We report the identification of a new class of antimicrobial peptidomimetics-γ-AApeptides with potent and broad-spectrum activity, including clinically-relevant strains that are unresponsive to most antibiotics. They are also not prone to select for drug-resistance.

Development of self-immolative dendrimers for drug delivery and sensing

Traditional dendrimers possess unique cascade-branched structural properties that allow for multivalent modifications with drug cargos, targeting/delivery agents and imaging tools. In addition to multivalency, the dendrimers macromolecular size also brings about the enhanced permeability and retention (EPR) effect, which makes it an attracting agent for drug delivery and biosensing. Similar to other macromolecules, therapeutic application of dendrimers in the human body faces practical challenges such as target specificity and toxicity. The latter represents a substantial issue due to the dendrimers unnatural chemical structure and relatively large size, which prohibit its in vivo degradation and excretion from the body. To date, a class of self-immolative dendrimers has been developed to overcome these obstacles, which takes advantage of its unique structural backbone to allow for cascade decompositions upon a simple triggering event. The specific drug release can be achieved through a careful design of the trigger, and as a result of the fragmentation, the generated small molecules are either biodegradable or easily excreted from the body. Though still at a preliminary stage, the development of this novel approach represents an important direction in nanoparticle-mediated drug delivery and sensor design, thereby opening up an insightful frontier of dendrimer based applications.

Lipidated cyclic γ-AApeptides display both antimicrobial and anti-inflammatory activity.

Antimicrobial peptides (AMPs) are host-defense agents capable of both bacterial membrane disruption and immunomodulation. However, the development of natural AMPs as potential therapeutics is hampered by their moderate activity and susceptibility to protease degradation. Herein we report lipidated cyclic γ-AApeptides that have potent antibacterial activity against clinically relevant Gram-positive and Gram-negative bacteria, many of which are resistant to conventional antibiotics. We show that lipidated cyclic γ-AApeptides mimic the bactericidal mechanism of AMPs by disrupting bacterial membranes. Interestingly, they also harness the immune response and inhibit lipopolysaccharide (LPS) activated Toll-like receptor 4 (TLR4) signaling, suggesting that lipidated cyclic γ-AApeptides have dual roles as novel antimicrobial and anti-inflammatory agents.

Berberine Inhibits Invasion and Metastasis of Colorectal Cancer Cells via COX-2/PGE2 Mediated JAK2/STAT3 Signaling Pathway.

Berberin, extracted from Chinese herbal medicine Coptis chinensis, has been found to have anti-tumor activities. However, the underlying mechanisms have not been fully elucidated. Our current study demonstrated that berberin inhibited the in vitro and in vivo growth, migration/invasion of CRC cells, via attenuating the expression levels of COX-2/PGE2, following by reducing the phosphorylation of JAK2 and STAT3, as well as the MMP-2/-9 expression. We further clarified that an increase of COX-2/PGE2 expression offset the repressive activity of Berberin on JAK2/STAT3 signaling, and a JAK2 inhibitor AZD1480 blocked the effect of COX-2/PGE2 on MMP-2/-9 expression. In summary, Berberin inhibited CRC invasion and metastasis via down-regulation of COX-2/PGE2- JAK2/STAT3 signaling pathway.