Li-Hui Xu

Jinan University (Guangzhou, China), Shengcheng, Guangdong, China

Are you Li-Hui Xu?

Claim your profile

Publications (42)104.82 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Gossypol, a polyphenolic compound isolated from cottonseeds, has been reported to possess many pharmacological activities, but whether it can influence inflammasome activation remains unclear. In this study, we found that in mouse macrophages, gossypol induced cell death characterized by rapid membrane rupture and robust release of HMGB1 and pro-caspase-11 comparable to ATP treatment, suggesting an induction of pyroptotic cell death. Unlike ATP, gossypol induced much low levels of mature interleukin-1β (IL-1β) secretion from mouse peritoneal macrophages primed with LPS, although it caused pro-IL-1β release similar to that of ATP. Consistent with this, activated caspase-1 responsible for pro-IL-1β maturation was undetectable in gossypol-treated peritoneal macrophages. Besides, RAW 264.7 cells lacking ASC expression and caspase-1 activation also underwent pyroptotic cell death upon gossypol treatment. In further support of pyroptosis induction, both pan-caspase inhibitor and caspase-1 subfamily inhibitor, but not caspase-3 inhibitor, could sharply suppress gossypol-induced cell death. Other canonical pyroptotic inhibitors, including potassium chloride and N-acetyl-L-cysteine, could suppress ATP-induced pyroptosis but failed to inhibit or even enhanced gossypol-induced cell death, whereas nonspecific pore-formation inhibitor glycine could attenuate this process, suggesting involvement of a non-canonical pathway. Of note, gossypol treatment eliminated thioglycollate-induced macrophages in the peritoneal cavity with recruitment of other leukocytes. Moreover, gossypol administration markedly decreased the survival of mice in a bacterial sepsis model. Collectively, these results suggested that gossypol induced pyroptosis in mouse macrophages via a non-canonical inflammasome pathway, which raises a concern for its in vivo cytotoxicity to macrophages.
    No preview · Article · Feb 2016 · Toxicology and Applied Pharmacology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mammalian target of rapamycin (mTOR) is an attractive target for new anticancer drug development. We recently developed in silico models to distinguish mTOR inhibitors and non-inhibitors. In this study, we developed an integrated strategy for identifying new mTOR inhibitors using cascaded in silico screening models. With this strategy, fifteen new mTOR kinase inhibitors including four compounds with IC50 values below 10 µM were discovered. In particular, compound 17 exhibited potent anticancer activities against four tumor cell lines, including MCF-7, HeLa, MGC-803, and C6, with IC50 values of 1.90, 2.74, 3.50 and 11.05 μM. Furthermore, cellular studies and western blot analyses revealed that 17 induces cell death via apoptosis by targeting both mTORC1 and mTORC2 within cells and arrests the cell cycle of HeLa at the G1/G0-phase. Finally, multi-nanosecond explicit solvent simulations and MM/GBSA analyses were carried out to study the inhibitory mechanisms of 13, 17, and 40 for mTOR. The potent compounds presented here are worthy of further investigation.
    Full-text · Article · Nov 2015 · Scientific Reports
  • [Show abstract] [Hide abstract]
    ABSTRACT: CPT-11 (Irinotecan) is a first-line chemotherapeutic agent in clinic, but it may induce side effects including diarrhea and enteritis in patients. The underlying mechanism of CPT-11's intestinal toxicity is unclear. Peritoneal resident macrophages have been reported to be important for the maintenance of intestinal homeostasis. In this study, we evaluated the cytotoxic effects of CPT-11 on mouse peritoneal resident macrophages. CPT-11 was administered intraperitoneally to mice and their peritoneal exudate cells were isolated for evaluation. CPT-11 treatment strikingly decreased the ratio of F4/80(hi)MHCII(low) large peritoneal macrophages (LPMs), which are regarded as prenatally-originated peritoneal resident macrophages. Consistent with this, the transcription factor GATA6 specifically expressed in LPMs was barely detectable in the macrophages from CPT-11-treated mice, indicative of elimination of LPMs. Such elimination of LPMs was at least partly due to CPT-induced apoptosis in macrophages, because inhibition of apoptosis by caspase-3 inhibitor z-DEVD-fmk significantly diminished the loss of GATA6(+) LPMs. As GATA6 is a transcription factor that controls expression of multiple genes regulating peritoneal B-1 cell development and translocation, elimination of GATA6(+) LPMs led to a great reduction in B-1 cells in the peritoneal cavity after CPT-11 treatment. These results indicated that CPT-11-induced apoptosis contributed to the elimination of peritoneal resident macrophages, which might in turn impair the function of peritoneal B-1 cells in maintaining intestinal homeostasis. Our findings may at least partly explain why CPT-11 treatment in cancer patients induces diarrhea and enteritis, which may provide a novel avenue to prevent such side effects.
    No preview · Article · Nov 2015 · Apoptosis
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Previously we reported that valproic acid (VPA) acts in synergy with GOS to enhance cell death in human DU145 cells. However, the underlying mechanism remains elusive. In this study, we observed that such synergistic cytotoxicity of GOS and VPA could be extended to human A375, HeLa, and PC-3 cancer cells. GOS and VPA co-treatment induced robust apoptosis as evidenced by caspase-8/-9/-3 activation, PARP cleavage, and nuclear fragmentation. GOS and VPA also markedly decreased cyclin A2 protein expression. Owing to the reduction of cyclin A2, Akt signaling was suppressed, leading to dephosphorylation of FOXO3a. Consequently, FOXO3a was activated and the expression of its target genes, including pro-apoptotic FasL and Bim, was upregulated. Supporting this, FOXO3a knockdown attenuated FasL and Bim upregulation and apoptosis induction in GOS+VPA-treated cells. Furthermore, blocking proteasome activity by MG132 prevented the downregulation of cyclin A2, dephosphorylation of Akt and FOXO3a, and induction of apoptosis in cells co-treated with GOS and VPA. In mouse model, GOS and VPA combination significantly inhibited the growth of A375 melanoma xenografts. Our findings indicate that GOS and VPA co-treatment induces apoptosis in human cancer cells by suppressing the cyclin-A2/Akt/FOXO3a pathway.
    Full-text · Article · Oct 2015 · Oncotarget
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pepper, a daily-used seasoning for promoting appetite, is widely used in folk medicine for treating gastrointestinal diseases. Piperine is the major alkaloid in pepper and possesses a wide range of pharmacological activities. However, the mechanism for linking metabolic and medicinal activities of piperine remains unknown. Here we report that piperine robustly boosts mTORC1 activity by recruiting more system L1 amino acid transporter (SLC7A5/SLC3A2) to the cell membrane, thus promoting amino acid metabolism. Piperine-induced increase of mTORC1 activity in resident peritoneal macrophages (pMΦs) is correlated with enhanced production of IL-6 and TNF-α upon LPS stimulation. Such an enhancement of cytokine production could be abrogated by inhibitors of the mTOR signaling pathway, indicating mTOR's action in this process. Moreover, piperine treatment protected resident pMΦs from bacterium-induced apoptosis and disappearance, and increased their bacterial phagocytic ability. Consequently, piperine administration conferred mice resistance against bacterial infection and even sepsis. Our data highlight that piperine has the capacity to metabolically reprogram peritoneal resident macrophages to fortify their innate functions against bacterial infection.
    Full-text · Article · Oct 2015 · Oncotarget
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cucurbitacins, the natural triterpenoids possessing many biological activities, have been reported to suppress the mTORC1/p70S6K pathway and to induce autophagy. However, the correlation between such activities is largely unknown. In this study, we addressed this issue in human cancer cells in response to cucurbitacin E (CuE) treatment. Our results showed that CuE induced autophagy as evidenced by the formation of LC3-II and colocalization of punctate LC3 with the lysosomal marker LAMP2 in HeLa and MCF7 cells. However, CuE induced much lower levels of autophagy in ATG5-knocked down cells and failed to induce autophagy in DU145 cells lacking functional ATG5 expression, suggesting the dependence of CuE-induced autophagy on ATG5. Consistent with autophagy induction, mTORC1 activity (as reflected by p70S6K and ULK1S758 phosphorylation) was inhibited by CuE treatment. The suppression of mTORC1 activity was further confirmed by reduced recruitment of mTOR to the lysosome, which is the activation site of mTORC1. In contrast, CuE rapidly activated AMPK leading to increased phosphorylation of its substrates. AMPK activation contributed to CuE-induced suppression of mTORC1/p70S6K signaling and autophagy induction, since AMPK knockdown diminished these effects. Collectively, our data suggested that CuE induced autophagy in human cancer cells at least partly via downregulation of mTORC1 signaling and upregulation of AMPK activity.
    Full-text · Article · May 2015 · PLoS ONE
  • [Show abstract] [Hide abstract]
    ABSTRACT: The anti-inflammatory effect of piperine has been largely investigated in macrophages, but its activity on epithelial cells in inflammatory settings is unclear. The present study aimed to investigate the effect of piperine on the expression of inflammatory cytokines in lipopolysaccharide (LPS)-stimulated human epithelial-like SW480 and HT-29 cells. Our data showed that although piperine inhibited the proliferation of SW480 and HT-29 cells in a dose-dependent manner, it had low cytotoxicity on these cell lines with 50 % inhibiting concentration (IC50) values greater than 100 μM. As epithelial-like cells, SW480 and HT-29 cells secreted high levels of the chemokine CXCL8 upon LPS stimulation. Importantly, piperine dose-dependently suppressed LPS-induced secretion of CXCL8 and the expression of CXCL8 messenger RNA (mRNA). Although piperine failed to affect the critical inflammatory nuclear factor-κB pathway, it attenuated the c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) signaling. Consistent with previous reports, p38 signaling seemed to play a more pronounced role on the CXCL8 expression than JNK signaling since inhibition of p38, instead of JNK, greatly suppressed LPS-induced CXCL8 expression. Collectively, our results indicated that piperine could attenuate the inflammatory response in epithelial cells via downregulating the MAPK signaling and thus the expression of CXCL8, suggesting its potential application in anti-inflammation therapy.
    No preview · Article · Dec 2014 · Inflammation
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ginsenoside Rg1 is one of the major active components of ginseng, which has been shown to regulate the immune response of hosts. However, the mechanism underlying the immunomodulatory effect of Rg1 is incompletely understood. In this study, we aimed to explore whether and how Rg1 regulates the innate immune response in macrophages. The results showed that Rg1 treatment significantly increased tumor necrosis factor (TNF)-α but decreased interleukin-6 (IL-6) protein expression in both lipopolysaccharide (LPS)-activated RAW 264.7 cells and mouse peritoneal macrophages. However, Rg1 reduced the mRNA levels of both cytokines in LPS-activated macrophages, which might be a consequence of decreased activation of IκB and nuclear factor-κB (NF-κB). Importantly, Rg1 treatment further promoted LPS-induced activation of the Akt/mechanistic target of rapamycin (mTOR) pathway, which is critical for controlling protein translation. The elevated Akt/mTOR signaling was likely responsible for increased production of TNF-α protein at the translational level, as suppression of this pathway by LY294002, an inhibitor of the upstream phosphatidylinositol 3-kinase (PI3K), abrogated such an enhancement of TNF-α protein expression even though its mRNA levels were conversely increased. These findings highlight a novel mechanism for Rg1 to regulate the innate immune response in macrophages through differentially modulating the NF-κB and PI3K/Akt/mTOR pathways.
    No preview · Article · Aug 2014 · International Immunopharmacology
  • [Show abstract] [Hide abstract]
    ABSTRACT: The anti-inflammatory property of chloroquine (CQ) has long been recognized. This study aimed to investigate the effect of CQ on proinflammatory cytokine expression in RAW 264.7 macrophages stimulated with heat-inactivated Staphylococcus aureus cells (SAC). The results showed that CQ treatment reduced the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and CC chemokine ligand 2 (CCL2) in culture medium but increased intracellular protein expression of TNF-α and CCL2 in SAC-activated cells. However, CQ showed differential effects on their messenger RNA (mRNA) levels: it reduced IL-6 mRNA expression, increased CCL2 mRNA levels, but had no effect on TNF-α mRNA. The SAC-activated inflammatory signaling pathways were slightly or minimally affected by CQ treatment. Additionally, CQ increased the accumulation of pro-TNF-α proteins within cells, suggesting an inhibition of pro-TNF-α processing and secretion. Collectively, CQ differentially modulated proinflammatory cytokine expression in Gram-positive bacterium-activated macrophages at multiple regulatory layers in the course of their biosynthesis.
    No preview · Article · Aug 2014 · Inflammation
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cucurbitacin B (CuB), a potent antineoplastic agent of cucurbitacin triterpenoids, induces rapid disruption of actin cytoskeleton and aberrant cell cycle inhibiting carcinogenesis. However, the underlying molecular mechanism of such anticancer effects remains incompletely understood. In this study, we showed that CuB treatment rapidly induced vasodilator-stimulated phosphoprotein (VASP) phosphorylation (i.e. activation) at the Ser157 residue and generated VASP clumps which were co-localized with amorphous actin aggregates prior to the formation of highly-ordered cofilin-actin rods in melanoma cells. Knockdown of VASP or inhibition of VASP activation using PKA-specific inhibitor H89 suppressed CuB-induced VASP activation, actin aggregation and cofilin-actin rod formation. The VASP activation was mediated by cAMP-independent PKA activation as CuB decreased the levels of cAMP while MDL12330A, an inhibitor of adenylyl cyclase, had weak effect on VASP activation. Knockdown of either Gα13 or RhoA not only suppressed VASP activation, but also ameliorated CuB-induced actin aggregation and abrogated cofilin-actin rod formation. Collectively, our studies highlighted that the CuB-induced actin aggregation and cofilin-actin rod formation was mediated via the Gα13/RhoA/PKA/VASP pathway.
    Full-text · Article · Apr 2014 · PLoS ONE
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cucurbitacin IIb (CuIIb) is one of the major active compounds in Hemsleyadine tablets which have been used for clinical treatment of bacillary dysentery, enteritis and acute tonsilitis. However, its action mechanism has not been completely understood. This study aimed to explore the anti-inflammatory activity of CuIIb and its underlying mechanism in mitogen-activated lymphocytes isolated from mouse mesenteric lymph nodes. The results showed that CuIIb inhibited the proliferation of concanavalin A (Con A)-activated lymphocytes in a time- and dose-dependent manner. CuIIb treatment arrested their cell cycle in S and G2/M phases probably due to the disruption of the actin cytoskeleton and the modulation of p27(Kip1) and cyclin levels. Moreover, the surface expression of activation markers CD69 and CD25 on Con A-activated CD3(+) T lymphocytes was suppressed by CuIIb treatment. Both Con A- and phorbol ester plus ionomycin-induced expression of TNF-α, IFN-γ and IL-6 proteins was attenuated upon exposure to CuIIb. Mechanistically, CuIIb treatment suppressed the phosphorylation of JNK and Erk1/2 but not p38 in Con A-activated lymphocytes. Although CuIIb unexpectedly enhanced the phosphorylation of IκB and NF-κB (p65), it blocked the nuclear translocation of NF-κB (p65). In support of this, CuIIb significantly decreased the mRNA levels of IκBα and TNF-α, two target genes of NF-κB, in Con A-activated lymphocytes. In addition, CuIIb downregulated Con A-induced STAT3 phosphorylation and increased cell apoptosis. Collectively, these results suggest that CuIIb exhibits its anti-inflammatory activity through modulating multiple cellular behaviors and signaling pathways, leading to the suppression of the adaptive immune response.
    Full-text · Article · Feb 2014 · PLoS ONE
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cross-talk between the mTOR (mechanistic target of rapamycin) and NF-κB (nuclear factor kappa-B) pathways has been reported to regulate macrophage responses to lipopolysaccharide (LPS). In this study, we aimed to explore the effect of INK128, a second-generation inhibitor of mTOR, on the inflammatory cytokine production in LPS-stimulated RAW 264.7 cells. Our data showed that INK128 strikingly inhibited the phosphorylation of p70S6K, 4E-BP1 and AKTSer473 in both unstimulated and LPS-stimulated cells. Although it increased the phosphorylation levels of inhibitor kappa-B (IκB) in LPS-stimulated cells, INK128 did not significantly change the levels of NF-κB phosphorylation. In addition, LPS-induced expression of IL-1β and IL-6 was markedly suppressed by INK128 at both mRNA and protein levels. However, the expression of Tumor necrosis factor-alpha (TNF-α protein), but not its mRNA level, was suppressed by this reagent. Our results suggest that the mTOR inhibitor INK128 not only regulates the NF-κB signaling but also influences the inflammatory cytokine expression at both transcriptional and translational levels.
    No preview · Article · Jan 2014 · Inflammation
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Autophagy is a conserved mechanism for controlling the degradation of misfolded proteins and damaged organelles in eukaryotes and can be induced by nutrient withdrawal, including serum starvation. Although differential acetylation of autophagy-related proteins has been reported to be involved in autophagic flux, the regulation of acetylated microtubule-associated protein 1 light chain 3 (LC3) is incompletely understood. In this study, we found that the acetylation levels of phosphotidylethanolamine (PE)-conjugated LC3B (LC3B-II), which is a critical component of double-membrane autophagosome, were profoundly decreased in HeLa cells upon autophagy induction by serum starvation. Pretreatment with lysosomal inhibitor chloroquine did not attenuate such deacetylation. Under normal culture medium, we observed increased levels of acetylated LC3B-II in cells treated with tubacin, a specific inhibitor of histone deacetylase 6 (HDAC6). However, tubacin only partially suppressed serum-starvation-induced LC3B-II deacetylation, suggesting that HDAC6 is not the only deacetylase acting on LC3B-II during serum-starvation-induced autophagy. Interestingly, tubacin-induced increase in LC3B-II acetylation was associated with p62/SQSTM1 accumulation upon serum starvation. HDAC6 knockdown did not influence autophagosome formation but resulted in impaired degradation of p62/SQSTM1 during serum starvation. Collectively, our data indicated that LC3B-II deacetylation, which was partly mediated by HDAC6, is involved in autophagic degradation during serum starvation.
    Full-text · Article · Nov 2013 · Biochemical and Biophysical Research Communications
  • [Show abstract] [Hide abstract]
    ABSTRACT: Accumulating evidence indicates that cucurbitacin B (CuB), as well as other cucurbitacins, damages the actin cytoskeleton in a variety of cell types. However, the underlying mechanism of such an effect is not well understood. In this study, we showed that CuB rapidly induced actin aggregation followed by actin rod formation in melanoma cells. Cofilin, a critical regulator of actin dynamics, was dramatically dephosphorylated (i.e. activated) upon CuB treatment. Notably, the activated cofilin subsequently formed rod-like aggregates which were highly colocalized with actin rods, indicating the formation of cofilin-actin rods. Cofilin knockdown significantly suppressed rod formation but did not prevent actin aggregation. Furthermore, knockdown of the cofilin phosphatase slingshot homolog 1 (SSH1), but not chronophin (CIN), alleviated CuB-induced cofilin hyperactivation and cofilin-actin rod formation. The activity of Rho kinase and LIM kinase, two upstream regulators of cofilin activation, was downregulated after cofilin hyperactivation. Pretreatment with a thiol-containing reactive oxygen species (ROS) scavenger N-acetyl cysteine, but not other ROS inhibitors without thiol groups, suppressed CuB-induced actin aggregation, cofilin hyperactivation and cofilin-actin rod formation, suggesting that thiol oxidation might be involved in these processes. Taken together, our results demonstrated that CuB-induced formation of cofilin-actin rods was mediated by SSH1-dependent but CIN-independent cofilin hyperactivation. J. Cell. Biochem. © 2013 Wiley Periodicals, Inc.
    No preview · Article · Oct 2013 · Journal of Cellular Biochemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: Piperine, an alkaloid from black and long peppers (Piper nigrum Linn & P. longum Linn), has been reported to exhibit antitumor activities in vitro and in vivo. To further understand the antitumor mechanism of piperine, we investigated the growth inhibitory effects of piperine on human prostate cancer DU145, PC-3 and LNCaP cells. Piperine treatment resulted in a dose-dependent inhibition of the proliferation of these cell lines. Cell cycle arrest at G0/G1 was induced and cyclin D1 and cyclin A were downregulated upon piperine treatment. Notably, the level of p21(Cip1) and p27(Kip1) was increased dose-dependently by piperine treatment in both LNCaP and DU145 but not in PC-3 cells, in line with more robust cell cycle arrest in the former two cell lines than the latter one. Although piperine induced low levels of apoptosis, it promoted autophagy as evidenced by the increased level of LC3B-II and the formation of LC3B puncta in LNCaP and PC-3 cells. The piperine-induced autophagic flux was further confirmed by assaying LC3-II accumulation and LC3B puncta formation in the presence of chloroquine, a well-known autophagy inhibitor. Taken together, these results indicated that piperine exhibited anti-proliferative effect in human prostate cancer cells by inducing cell cycle arrest and autophagy.
    No preview · Article · Aug 2013 · Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cucurbitacin IIa (CuIIa), a member of cucurbitacin family, is isolated from the root of Hemsleya amabilis which has been used as an ancient remedy for bacillary dysentery and gastroenteritis. The anti-inflammatory properties of CuIIa have long been recognized but the underlying mechanism is largely unknown. In this study, we investigated the anti-inflammatory effect of CuIIa on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. The results showed that CuIIa inhibited the proliferation and migration of RAW 264.7 cells in a dose-dependent manner. Whereas CuIIa did not cause apoptosis in unstimulated RAW264.7 cells, it did induce a significant apoptosis in LPS-stimulated cells, which was caspase-3-dependent and associated with downregulation of survivin. Furthermore, LPS induced autophagy in RAW 264.7 cells and this effect was further enhanced by CuIIa as evidenced by increased levels of LC3-II conjugates and formation of LC3 puncta. In addition, CuIIa disrupted actin cytoskeleton via inducing actin aggregation. However, neither the synthesis of tumor necrosis factor-α, nor the activation of the mitogen-activated protein kinases and NF-κB pathways in LPS-stimulated cells was suppressed by CuIIa treatment. Collectively, these results suggested that induction of apoptosis and enhancement of autophagy contributed to the anti-inflammatory activity of CuIIa against inflammation-related diseases.
    No preview · Article · Mar 2013 · International immunopharmacology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective: Cucurbitacin E (CuE), a triterpenoid compound isolated from Cucurbitaceae plants, possesses a wide range of biological activities including anti-inflammatory properties. The present study aimed to investigate the anti-inflammatory effect of CuE and the underlying mechanism of action. Methods: The anti-inflammatory effect of CuE was evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Cell proliferation was assessed using a modified MTT assay. Cell cycle distribution was analyzed by propidium iodide staining. The actin cytoskeleton was examined by immunofluorescent staining. The expression of tumor necrosis factor (TNF)-α and interleukin (IL)-1β was determined by intracellular cytokine staining. G-actin level and nuclear factor (NF)-κB nuclear translocation were detected by immunoblotting. Results: CuE inhibited cell proliferation and induced cell cycle arrest at G2/M phase in RAW 264.7 cells. CuE also suppressed LPS-induced cell spreading and pseudopodia formation. These effects were associated with decreased G-actin level and severe actin aggregation. Moreover, CuE significantly inhibited both TNF-α and IL-1β production in LPS-stimulated RAW 264.7 cells. This was likely mediated by suppressing LPS-induced nuclear translocation of NF-κB, a critical transcription factor responsible for pro-inflammatory cytokine expression. Conclusion: CuE displayed anti-inflammatory effects through suppression of NF-κB nuclear translocation leading to a decreased expression of TNF-α and IL-1β in LPS-stimulated RAW 264.7 cells.
    No preview · Article · Jan 2013 · Agents and Actions
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Autophagic responses to chemotherapeutic agents may vary greatly among different prostate cancer cells and have not been well characterized. In this study, we showed that valproic acid (VPA) induced conversion of LC3-I to LC3-II and formation of LC3 puncta, the typical markers of autophagy, in LNCaP and PC-3 cells. However, these markers were undetectable in DU145 cells upon autophagic stimulation, indicating a defect of autophagy in this cell line. Among several critical autophagy-related proteins, ATG5 and ATG12-ATG5 conjugates, which are essential for autophagy induction, were absent in DU145 cells. No canonical transcripts for full-length ATG5 but only two alternatively spliced ATG5 transcripts were identified in DU145 cells. These alternative transcripts lack one or two exons, leading to premature termination of ATG5 translation. Transfection of the wild-type ATG5 gene into DU145 cells rescued the production of ATG5 and ATG12-ATG5 conjugates, resulting in formation of LC3-II conjugates and LC3 puncta. Moreover, the levels of the SQSTM1 protein, which should be degradable as an autophagy adaptor, were much higher in DU145 than in LNCaP and PC-3 cells, but were significantly decreased after ATG5 restoration in DU145 cells. However, expression of wild-type ATG5 in DU145 or knockdown of ATG5 in LNCaP and PC-3 cells did not change the inhibitory effects of VPA on these cells. Collectively, these results indicated that VPA-induced autophagy in prostate cancer cells depended on ATG5 and more importantly, that the autophagy pathway was genetically impaired in DU145 cells, suggesting caution in interpreting autophagic responses in this cell line.
    Full-text · Article · Oct 2012 · Autophagy
  • [Show abstract] [Hide abstract]
    ABSTRACT: The cucurbitacins are a class of triterpenoid molecules that possess cytotoxic characteristics for plant defense against herbivore feeding. 23,24-dihydrocucurbitacin F (DHCF), a derivative of the cucurbitacin family, has been isolated as an active component from the root of Hemsleya amabilis (Cucurbitaceae), an ancient Chinese remedy for bacillary dysentery, gastroenteritis, and cancers. While the toxicity of other cucurbitacins has been explored in several cancers, little data exist on the effect of DHCF on human cancers, including prostate cancer (PCa). In this study, we explore the level and mechanisms of DHCF toxicity on human PCa cell lines. Human PCa DU145, PC3, and LNCaP cells were treated with graded doses of DHCF in vitro, and anti-proliferative, cytotoxic, and proteomic effects were determined using MTS assay, cell cycle analysis, immunofluorescent staining, and western blotting. DHCF inhibited cell growth and induced cell cycle arrest at G(2)/M phase, formation of binucleated cells, and increased levels of apoptosis in all PCa cell lines tested. G-actin depletion, actin aggregation, and rod-like actin fibers, with little effect on microtubule structure, were observed after DHCF treatment. Actin aggregation and cofilin-actin rod formation were highly correlated with rapid and persistent dephosphorylation of cofilin-1 (cofilin). DHCF treatment resulted in upregulation of p21(Cip1) and downregulation of cyclin A in all three PCa cell lines. The anti-proliferative activity of DHCF on human PCa cells may be brought about by inducing actin aggregation and cofilin-actin rod formation, leading to cell cycle arrest, cytokinesis failure, and apoptosis.
    No preview · Article · Jul 2012 · Cancer Chemotherapy and Pharmacology
  • [Show abstract] [Hide abstract]
    ABSTRACT: The present study aimed to explore the antitumor effect and action mechanism of cucurbitacin B (CuB) on human T-cell leukemia Jurkat cells. Cell proliferation was measured by the MTS assay. Cell cycle distribution, mitochondrial membrane potential and annexin V staining were analyzed using flow cytometry. Western blotting was used to determine the levels of apoptosis- and autophagy-related proteins. CuB inhibited the proliferation of Jurkat cells in a dose-dependent manner and induced G 2 /M phase arrest as well as formation of tetraploid cells. Accompanied with these effects, the actin dynamics was disrupted, and cofilin, a key regulator of actin dynamics, was persistently activated (dephosphorylated). Although CuB induced around 10% cells undergoing apoptosis, most of the cells were alive after CuB treatment for 24 h. Induction of autophagy was also evident by accumulation of LC3-II. CuB-induced autophagy seemed to be a prosurvival response, since suppression of CuB-induced autophagy significantly increased the activation of caspase-3. Our results demonstrated that CuB exhibited antitumor activity in Jurkat cells through induction of cell cycle arrest and apoptosis which was at least partly due to the disruption of actin dynamics.
    No preview · Article · Jun 2012 · Pharmacology

Publication Stats

261 Citations
104.82 Total Impact Points

Institutions

  • 2005-2015
    • Jinan University (Guangzhou, China)
      Shengcheng, Guangdong, China
  • 2005-2014
    • University of Jinan (Jinan, China)
      Chi-nan-shih, Shandong Sheng, China
  • 2004
    • Guangzhou University
      Shengcheng, Guangdong, China