Epigenetic regulation of asymmetric cell division by the LIBR-BRD4 axis.

Asymmetric cell division (ACD) is a mechanism used by stem cells to maintain the number of progeny. However, the epigenetic mechanisms regulating ACD remain elusive. Here we show that BRD4, a BET domain protein that binds to acetylated histone, is segregated in daughter cells together with H3K56Ac and regulates ACD. ITGB1 is regulated by BRD4 to regulate ACD. A long noncoding RNA (lncRNA), LIBR (LncRNA Inhibiting BRD4), decreases the percentage of stem cells going through ACD through interacting with the BRD4 mRNAs. LIBR inhibits the translation of BRD4 through recruiting a translation repressor, RCK, and inhibiting the binding of BRD4 mRNAs to polysomes. These results identify the epigenetic regulatory modules (BRD4, lncRNA LIBR) that regulate ACD. The regulation of ACD by BRD4 suggests the therapeutic limitation of using BRD4 inhibitors to treat cancer due to the ability of these inhibitors to promote symmetric cell division that may lead to tumor progression and treatment resistance.

Ginkgolide B promotes neuronal differentiation through the Wnt/ß-catenin pathway in neural stem cells of the postnatal mammalian subventricular zone.

Chinese herbal medicines (CHMs) have been used to treat human diseases for thousands of years. Among them, Ginkgo biloba is reported to be beneficial to the nervous system and a potential treatment of neurological disorders. Since the presence of adult neural stem cells (NSCs) brings hope that the brain may heal itself, whether the effect of Ginkgo biloba is on NSCs remains elusive. In this study, we found that Ginkgo biloba extract (GBE) and one of its main ingredients, ginkgolide B (GB) promoted cell cycle exit and neuronal differentiation in NSCs derived from the postnatal subventricular zone (SVZ) of the mouse lateral ventricle. Furthermore, the administration of GB increased the nuclear level of ß-catenin and activated the canonical Wnt pathway. Knockdown of ß-catenin blocked the neurogenic effect of GB, suggesting that GB promotes neuronal differentiation through the Wnt/ß-catenin pathway. Thus, our data provide a potential mechanism underlying the therapeutic effect of GBE or GB on brain injuries and neurodegenerative disorders.

Chalcone flavokawain B induces autophagic-cell death via reactive oxygen species-mediated signaling pathways in human gastric carcinoma and suppresses tumor growth in nude mice.

Flavokawain B (FKB), a naturally occurring chalcone in kava extracts, has been reported to possess anticancer activity. However, the effect of FKB on gastric cancer remains unclear. We examined the in vitro and in vivo anticancer activity and autophagy involvement of FKB and determined the underlying molecular mechanisms. FKB is potently cytotoxic to human gastric cancer cells (AGS/NCI-N87/KATO-III/TSGH9201) and mildly toxic towards normal (Hs738) cells and primary mouse hepatocytes. FKB-induced AGS cell death was characterized by autophagy, not apoptosis, as evidenced by increased LC3-II accumulation, GFP-LC3 puncta and acidic vesicular organelles (AVOs) formation, without resulting procaspase-3/PARP cleavage. FKB further caused p62/SQSTM1 activation, mTOR downregulation, ATG4B inhibition, and Beclin-1/Bcl-2 dysregulation. Silencing autophagy inhibitors CQ/3-MA and LC3 (shRNA) significantly reversed the FKB-induced cell death of AGS cells. FKB-triggered ROS generation and ROS inhibition by NAC pre-treatment diminished FKB-induced cell death, LC3 conversion, AVO formation, p62/SQSTM1 activation, ATG4B inhibition and Beclin-1/Bcl-2 dysregulation, which indicated ROS-mediated autophagy in AGS cells. Furthermore, FKB induces G2/M arrest and alters cell-cycle proteins through ROS-JNK signaling. Interestingly, FKB-induced autophagy is associated with the suppression of HER-2 and PI3K/AKT/mTOR signaling cascades. FKB inhibits apoptotic Bax expression, and Bax-transfected AGS cells exhibit both apoptosis and autophagy; thus, FKB-inactivated Bax results in apoptosis inhibition. In vivo data demonstrated that FKB effectively inhibited tumor growth, prolonged the survival rate, and induced autophagy in AGS-xenografted mice. Notably, silencing of LC3 attenuated FKB-induced autophagy in AGS-xenografted tumors. FKB may be a potential chemopreventive agent in the activation of ROS-mediated autophagy of gastric cancer cells.

Inhibition of ROS production, autophagy or apoptosis signaling reversed the anticancer properties of Antrodia salmonea in triple-negative breast cancer (MDA-MB-231) cells.

We investigated the in vitro and in vivo anticancer properties of Antrodia salmonea (AS), a well-known edible/medicinal mushroom in Taiwan, on human triple-negative breast cancer (MDA-MB-231) cells and xenografted nude mice; and revealed the underlying molecular mechanisms involved in autophagic- and apoptotic-cell death. Treatment of MDA-MB-231 cells with fermented culture broth of AS (0-200 µg/mL) inhibited cell viability/growth. AS-induced autophagy was evidenced via increased LC3-II accumulation, GFP-LC3 puncta and AVOs formation in MDA-MB-231 cells. These events are associated with increased ATG7, decreased p-mTOR, vanished SQSTM1/p62 expressions and dysregulated Beclin-1/Bcl-2 ratio. AS-induced apoptosis/necrosis through increased DNA fragmentation, Annexin-V/PI stained cells and Bax expression. Both mitochondrial (caspase-9/caspase-3/PARP) and death-receptor (caspase-8/FasL/Fas) signaling pathways are involved in execution of apoptosis. Interestingly, blockade of AS-induced ROS production by N-acetylcysteine pretreatment substantially attenuated AS-induced autophagy, mitochondrial dysfunction and autophagic/apoptotic-cell death. Inhibition of apoptosis by Z-VAD-FMK suppressed AS-induced autophagic-death (decreased LC3-II/AVOs). Similarly, inhibition of autophagy by 3-methyladenine/chloroquine diminished AS-induced apoptosis (decreased DNA fragmentation/caspase-3) in MDA-MB-231 cells. Bioluminescence imaging further confirmed that AS inhibited breast tumor growth in living MDA-MB-231-luciferase-injected nude mice. Taken together, AS crucially involved in execution/propagation of autophagic- or apoptotic-death of MDA-MB-231 cells, and decreased tumor growth in xenografted nude mice.

Antrodia salmonea induces G2 cell-cycle arrest in human triple-negative breast cancer (MDA-MB-231) cells and suppresses tumor growth in athymic nude mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Antrodia salmonea (AS), is a well-known folk medicinal mushroom in Taiwan, has been reported to exhibit anti-oxidant, anti-angiogenic, and anti-inflammatory effects. MATERIALS AND METHODS: In the present study, we examined the effects of AS on cell-cycle arrest in vitro in MDA-MB-231 cells and on tumor regression in vivo using an athymic nude mice model. RESULTS: AS (0-200µg/mL) treatment significantly induced G2 cell-cycle arrest in MDA-MB-231 cells by reducing the levels of cyclin B1, cyclin A, cyclin E, and CDC2 proteins. In addition, N-acetylcysteine (NAC) pretreatment prevented AS induced G2 cell-cycle arrest, indicating that ROS accumulation and subsequent cell cycle arrest might be a major mechanism of AS-induced cytotoxicity. Further, AS treatment decreased COX-2 expression and induced PARP cleavage was significantly reversed by NAC pretreatment in MDA-MB-231 cells. The in vivo study results revealed that AS treatment was effective in terms of delaying the tumor incidence and reducing the tumor growth in MDA-MB-231-xenografted nude mice. TUNEL assay, immunohistochemical staining and Western blotting confirmed that AS significantly modulated the xenografted tumor progression as demonstrated by induction of apoptosis, autophagy, and cell-cycle arrest. CONCLUSION: Our data strongly suggest that Antrodia salmonea could be an anti-cancer agent for human breast cancer.

Lucidone Promotes the Cutaneous Wound Healing Process via Activation of the PI3K/AKT, Wnt/ß-catenin and NF-κB Signaling Pathways.

Lucidone, which comprises a naturally occurring cyclopentenedione, has been investigated for its in vitro and in vivo wound healing properties, and the underlying molecular signaling cascades in the wound healing mechanism have been elucidated. We demonstrated the cell-/dose-specific responses of lucidone (0.5-8µM) on proliferation and migration/invasion of keratinocyte HaCaT and fibroblast Hs68 cells. In keratinocytes, lucidone-induced nuclear translocation of ß-catenin was accompanied by increased transcriptional target genes, including c-Myc and cyclin-D1, through GSK3ß-dependent pathway. Correspondingly, lucidone promoted the cell-cycle by increasing PCNA/CDK4 and decreasing p21/p27 expressions. Lucidone induced EMT through the downregulation of epithelial (E-cadherin/occludin) and upregulation of mesenchymal (vimentin/Twist/Snail) marker proteins. Activated MMP-9/-2 and uPA/uPAR as well as suppressed TIMP-1/-2 and PAI-1 expressions by lucidone may promote the migration/invasion of keratinocytes. Notably, lucidone activated NF-κB signaling via IKK-mediated-IκB degradation, and its inhibition abolished MMP-9 activation and keratinocyte migration. Inhibition of PI3K/AKT signaling impaired the lucidone-induced proliferation/migration with corresponding suppression of ß-catenin/c-Myc/cyclin-D1 and NF-κB/MMP-9 expressions. Results indicate that lucidone-induced PI3K/AKT signaling anchored the ß-catenin/NF-κB-mediated healing mechanism. ß-catenin knockdown substantially diminished lucidone-induced keratinocyte migration. Furthermore, lucidone increased endothelial cell proliferation/migration and triggered angiogenesis (MMP-9/uPA/ICAM-1). In macrophages, lucidone-activated NF-κB-mediated inflammation (COX-2/iNOS/NO) and VEGF, which may contribute to the growth of keratinocytes/fibroblasts and endothelial cells. Punched wounds on mice were rapidly healed with the topical application of lucidone (5mM) compared with control ointment-treated mice. Taken together, lucidone accelerates wound healing through the cooperation of keratinocyte/fibroblast/endothelial cell growth and migration and macrophage inflammation via PI3K/AKT, Wnt/ß-catenin and NF-κB signaling cascade activation.

Toona sinensis Inhibits Murine Leukemia WEHI-3 Cells and Promotes Immune Response In Vivo.

Toona sinensis (TS) is one of the most popular vegetarian dishes in Taiwan. It has been shown to exhibit antioxidant, antiangiogenic, antiatherosclerotic, and anticancer properties. In this study, we demonstrated the ability of aqueous leaf extracts from TS to promote immune responses in BALB/c mice and to exhibit anti-leukemia activity in murine WEHI-3 cells. BALB/c mice were injected intravenously with WEHI-3 cells and then treated orally with TS (50 mg/kg). In vivo study showed that TS treatment reduced liver and spleen enlargement in WEHI-3 bearing mice compared with the untreated group. Furthermore, TS also decreased white blood cells (WBC), indicating inhibition of differentiation of the precursor of macrophages in WEHI-3 bearing mice. Treatment of WEHI-3 cells with TS (0-75 µg/mL for 24 hours) significantly reduced cell viability. Furthermore, TS treatment-induced late apoptosis was confirmed by Annexin-V/PI staining. Western blot analyses revealed that treatment of WEHI-3 cells with TS statistically increased the protein expression level of cytochrome c in the cytoplasm and activates caspase-3. Notably, TS treatment caused a dramatic reduction in Bcl-2 and increase in Bax protein levels. TS may disturb the Bcl-2 and Bax protein ratio and induce apoptosis. This reports confirms the antitumor activity of this nutritious vegetable potentially against leukemia.

Coenzyme Q0 regulates NFκB/AP-1 activation and enhances Nrf2 stabilization in attenuation of LPS-induced inflammation and redox imbalance: Evidence from in vitro and in vivo studies.

Coenzyme Q (CoQ) analogs with variable number of isoprenoid units have been demonstrated as anti-inflammatory and antioxidant/pro-oxidant molecules. In this study we used CoQ0 (2,3-dimethoxy-5-methyl-1,4-benzoquinone, zero isoprenoid side-chains), a novel quinone derivative, and investigated its molecular actions against LPS-induced inflammation and redox imbalance in murine RAW264.7 macrophages and mice. In LPS-stimulated macrophages, non-cytotoxic concentrations of CoQ0 (2.5-10 µM) inhibited iNOS/COX-2 protein expressions with subsequent reductions of NO, PGE2, TNF-α and IL-1ß secretions. This inhibition was reasoned by suppression of NFκB (p65) activation, and inhibition of AP-1 (c-Jun., c-Fos, ATF2) translocation. Our findings indicated that IKKα-mediated I-κB degradation and MAPK-signaling are involved in regulation of NFκB/AP-1 activation. Furthermore, CoQ0 triggered HO-1 and NQO-1 genes through increased Nrf2 nuclear translocation and Nrf2/ARE-signaling. This phenomenon was confirmed by diminished CoQ0 protective effects in Nrf2 knockdown cells, where LPS-induced NO, PGE2, TNF-α and IL-1ß productions remained high. Molecular evidence revealed that CoQ0 enhanced Nrf2 steady-state level at both transcriptional and translational levels. CoQ0-induced Nrf2 activation appears to be regulated by ROS-JNK-signaling cascades, as evidenced by suppressed Nrf2 activation upon treatment with pharmacological inhibitors of ROS (N-acetylcysteine) and JNK (SP600125). Besides, oral administration of CoQ0 (5 mg/kg) suppressed LPS-induced (1 mg/kg) induction of iNOS/COX-2 and TNF-α/IL-1ß through tight regulation of NFκB/Nrf2 signaling in mice liver and spleen. Our findings conclude that pharmacological actions of CoQ0 are mediated via inhibition of NFκB/AP-1 activation and induction of Nrf2/ARE-signaling. Owing to its potent anti-inflammatory and antioxidant properties, CoQ0 could be a promising candidate to treat inflammatory disorders.

Induction of macrophage cell-cycle arrest and apoptosis by humic acid.

Humic acid (HA) in well water is associated with Blackfoot disease and various cancers. Previously, we reported that acute humic acid exposure (25-200 µg/mL for 24 hr) induces inflammation in RAW264.7 macrophages. In this study, we observed that prolonged (72 hr) HA exposure (25-200 µg/mL) induces cell-cycle arrest and apoptosis in cultured RAW264.7 cells. We also observed that exposing macrophages to HA arrests cells in the G2 /M phase of the cell cycle by reducing cyclin A/B1 , Cdc2, and Cdc25C levels. Treating macrophages with HA triggers a sequence of events characteristic of apoptotic cell death including loss of cell viability, morphological changes, internucleosomal DNA fragmentation, sub-G1 accumulation. Molecular markers of apoptosis associated with mitochondrial dysfunction were similarly observed, including cytochrome c release, caspase-3 or caspase-9 activation, and Bcl-2/Bax dysregulation. In addition to the mitochondrial pathway, HA-induced apoptosis may also be mediated through the death receptor and ER stress pathways, as evidence by induction of Fas, caspase-8, caspase-4, and caspase-12 activity. HA also upregulates p53 expression and causes DNA damage as assessed by the comet assay. These findings yield new insight into the mechanisms by which HA exposure may trigger atherosclerosis through modulation of the macrophage-mediated immune system.