Ping-hui Tseng - Academia.edu (original) (raw)

Papers by Ping-hui Tseng

Scientific reports, 2015

Toll-like receptor 4 (TLR4) plays an important role in innate immunity by eliciting inflammation.... more Toll-like receptor 4 (TLR4) plays an important role in innate immunity by eliciting inflammation. Upon receptor engagement, transforming growth factor β-activated kinase 1 (TAK1) is an essential mediator that transmits a signal from the receptor to downstream effectors, IκB kinase (IKK) and the mitogen-activated protein kinases (MAPKs), which control the production of inflammatory cytokines. However, the association between phosphorylation and ubiquitination of TAK1 is not yet clear. Here, we examined the crosstalk between phosphorylation and polyubiquitination of TAK1 and further investigated the mechanism of distinct activation of MAPKs and IKK. Inhibition of TAK1 phosphorylation enhanced Lys63-linked polyubiquitination of TAK1. Conversely, ubiquitin modification was counteracted by phospho-mimic TAK1 mutant, T(184,187)D. Moreover, using LC-MS analysis, Lys562 of TAK1 was identified as a novel Lys63-linked ubiquitination site and as the key residue in the feedback regulation. Muta...

Molecular Cancer Therapeutics

Evidence suggests that the angiogenic endothelium represents an important target through which ce... more Evidence suggests that the angiogenic endothelium represents an important target through which celecoxib mediates in vivo antitumor effects. Nevertheless, the pharmacologic basis for celecoxib-caused growth inhibition in endothelial cells in vitro remains to be defined. Previously, we showed that celecoxib-induced apoptosis in PC-3 prostate cancer cells was mediated in part through the inhibition of 3-phosphoinositide-dependent kinase-1/Akt signaling. Our present findings show that celecoxib inhibits the growth of human umbilical vein endothelial cells (HUVEC) with pharmacologic profiles reminiscent of those of PC-3 cells. The underlying antiproliferative mechanism, however, may differ between these two cell types considering differences in the functional status of many tumor suppressors, including PTEN, p53, and retinoblastoma, all of which play integral roles in regulating cell cycle progression and survival. From a mechanistic perspective, the genomic integrity of the HUVEC syste...

PloS one, 2014

CpG-oligodeoxynucleotides (CpG-ODN) are potent immune stimuli being developed for use as adjuvant... more CpG-oligodeoxynucleotides (CpG-ODN) are potent immune stimuli being developed for use as adjuvants in different species. Toll-like receptor 9 (TLR9) is the cellular receptor for CpG-ODN in mammalian cells. The CpG-ODN with 18-24 deoxynucleotides that are in current use for human and mouse cells, however, have low activity with rabbit TLR9. Using a cell-based activation assay, we developed a type of CpG-ODN containing a GACGTT or AACGTT motif in 12 phosphorothioate-modified deoxynucleotides with potent stimulatory activity for rabbit TLR9. The developed CpG-ODN have higher activities than other developed CpG-ODN in eliciting antigen-nonspecific immune responses in rabbit splenocytes. When mixed with an NJ85 peptide derived from rabbit hemorrhagic disease virus, they had potent activities to boost an antigen-specific T cell activation and antibody production in rabbits. Compared to Freund's adjuvant, the developed CpG-ODN are capable of boosting a potent and less toxic antibody re...

Neoplasia (New York, N.Y.), 2014

Hepatocellular carcinoma is the fifth most common solid cancer worldwide. Sorafenib, a small mult... more Hepatocellular carcinoma is the fifth most common solid cancer worldwide. Sorafenib, a small multikinase inhibitor, is the only approved therapy for advanced HCC. The clinical benefit of sorafenib is offset by the acquisition of sorafenib resistance. Understanding of the molecular mechanism of STAT3 overexpression in sorafenib resistance is critical if the clinical benefits of this drug are to be improved. In this study, we explored our hypothesis that loss of RFX-1/SHP-1 and further increase of p-STAT3 as a result of sorafenib treatment induces sorafenib resistance as a cytoprotective response effect, thereby, limiting sorafenib sensitivity and efficiency. We found that knockdown of RFX-1 protected HCC cells against sorafenib-induced cell apoptosis and SHP-1 activity was required for the process. SC-2001, a molecule with similar structure to obatoclax, synergistically suppressed tumor growth when used in combination with sorafenib in vitro and overcame sorafenib resistance through ...

Chemico-biological interactions, Jan 25, 2015

Obatoclax is an indole-pyrrole compound that induces cancer cell apoptosis through targeting the ... more Obatoclax is an indole-pyrrole compound that induces cancer cell apoptosis through targeting the anti-apoptotic Bcl-2 protein family. Previously, we developed a series of obatoclax derivatives and studied their STAT3 inhibition-dependent activity against cancer cell lines. The obatoclax analog, prodigiosin, has been reported to mediate DNA cleavage in cancer cells by coordinating with copper complexes. To gain an understanding of copper-obatoclax complex activity, we applied obatoclax derivatives to examine their copper-mediated nuclease activity as a means to establish a basis for structure activity relationship. Replacement of the indole ring of obatoclax with furanyl, thiophenyl or Boc-indolyl rings reduced the DNA cleavage ability. The same effect was achieved through the replacement of the obatoclax pyrrolyl ring with thiazolidinedione and thioacetal. Among the compounds tested, we demonstrated that the complex of obatoclax or compound 7 with copper exhibited potent DNA strand ...

Regarding the involvement of cyclooxygenase-2 (COX-2)-independent pathways in celecoxib-mediated ... more Regarding the involvement of cyclooxygenase-2 (COX-2)-independent pathways in celecoxib-mediated antineoplastic effects, the following two issues remain outstanding: identity of the non-COX-2 targets and relative contributions of COX-2-dependent versus -independent mechanisms. We use a close celecoxib analog deficient in COX-2-inhibitory activity, DMC {4-(5-(2,5-dimethylphenyl)-3(trifluoromethyl)-1H-pyrazol-1-yl)benzene- sulfonamide}, to examine the premise that Akt signaling represents a major non-COX-2 target. Celecoxib and DMC block Akt

Tetrahedron Letters, 2000

A concise synthesis of the O-glycosylated amino acid building block; using phenyl selenoglycoside... more A concise synthesis of the O-glycosylated amino acid building block; using phenyl selenoglycoside as a glycosyl donor

Science, 2008

Cytokine signaling is thought to require assembly of multi-component signaling complexes at cytop... more Cytokine signaling is thought to require assembly of multi-component signaling complexes at cytoplasmic segments of membrane-embedded receptors, in which receptor-proximal protein kinases are activated. Indeed, CD40, a tumor necrosis factor receptor (TNFR) family member, forms a complex containing adaptor molecules TRAF2 and TRAF3, ubiquitin conjugating enzyme Ubc13, cellular inhibitor of apoptosis proteins 1 and 2 (c-IAP1/2), IκB kinase regulatory subunit IKKγ (also called NEMO) and mitogen-activated protein kinase (MAPK) kinase kinase MEKK1 upon ligation. TRAF2, Ubc13, and IKKγ were required for complex assembly and activation of MEKK1 and MAPK cascades. However, these kinases were not activated unless the multi-component signaling complex translocated from CD40 to the cytosol upon c-IAP1/2-induced degradation of TRAF3. This twostage signaling mechanism may apply to other innate immune receptors, accounting for spatial and temporal separation of MAPK and IKK signaling.

Proceedings of the National Academy of Sciences, 2008

NOD2, a NOD-like receptor (NLR), is an intracellular sensor of bacterial muramyl dipeptide (MDP) ... more NOD2, a NOD-like receptor (NLR), is an intracellular sensor of bacterial muramyl dipeptide (MDP) that was suggested to promote secretion of the proinflammatory cytokine IL-1␤. Yet, the molecular mechanism by which NOD2 can stimulate IL-1␤ secretion, and its biological significance were heretofore unknown. We found that NOD2 through its N-terminal caspase recruitment domain directly binds and activates caspase-1 to trigger IL-1␤ processing and secretion in MDP-stimulated macrophages, whereas the C-terminal leucine-rich repeats of NOD2 prevent caspase-1 activation in nonstimulated cells. MDP challenge induces the association of NOD2 with another NLR protein, NALP1, and gel filtration analysis revealed the formation of a complex consisting of NOD2, NALP1, and caspase-1. Importantly, Bacillus anthracis infection induces IL-1␤ secretion in a manner that depended on caspase-1 and NOD2. In vitro, Anthrax lethal toxin strongly potentiated IL-1␤ secretion, and that response was NOD2 and caspase-1-dependent. Thus, NOD2 plays a key role in the B. anthracis-induced inflammatory response by being a critical mediator of IL-1␤ secretion.

Proceedings of the National Academy of Sciences, 2008

Modification of proteins by the addition of lysine (K)-63-linked polyubiquitin (polyUb) chains is... more Modification of proteins by the addition of lysine (K)-63-linked polyubiquitin (polyUb) chains is suggested to play important roles in a variety of cellular events, including DNA repair, signal transduction, and receptor endocytosis. However, identifying such modifications in living cells is complex and cumbersome. We have generated a monoclonal antibody (mAb) that specifically recognizes K63-linked polyUb, but not any other isopeptide-linked (K6, K11, K27, K29, K33, or K48) polyUb or monoubiquitin. We demonstrate the sensitivity and specificity of this K63Ub-specific mAb to detect K63Ub-modified proteins in cell lysates by Western blotting and in cells by immunofluorescence, and K63Ub-modified TRAF6 and MEKK1 in vitro and ex vivo. This unique mAb will facilitate the analysis of K63-linked polyubiquitylation ex vivo and presents a strategy for the generation of similar reagents against other forms of polyUb.

Nature Reviews Immunology, 2011

Tumour necrosis factor receptor (TNFR)-associated factor (TRAF) proteins are essential components... more Tumour necrosis factor receptor (TNFR)-associated factor (TRAF) proteins are essential components of signalling pathways activated by TNFR or Toll-like receptor (TLR) family members. Acting alone or in combination, the seven known TRAFs control many biological processes, including cytokine production and cell survival. The function of one TRAF in particular, TRAF3, remained elusive for many years. Recent work has revealed that TRAF3 is a highly versatile regulator that positively controls type I interferon production, but negatively regulates mitogen-activated protein kinase activation and alternative nuclear factor-κB signalling. In this Review, we discuss our current understanding of the role of TRAF3 in TNFR and TLR signalling pathways, and its role in disease.

Nature Immunology, 2008

The adaptor and signaling proteins TRAF2, TRAF3 and cIAP1 and cIAP2 were suggested to inhibit alt... more The adaptor and signaling proteins TRAF2, TRAF3 and cIAP1 and cIAP2 were suggested to inhibit alternative nuclear factor kappa B (NF-κB) signaling in resting cells by targeting NF-κB inducing kinase (NIK) to ubiquitin-dependent degradation, thus preventing processing of the NF-κB2 precursor protein p100 to release p52. However, the respective functions of TRAF2 and TRAF3 in NIK degradation and activation of alternative NF-κB signaling has remained elusive. We now show that CD40 or BAFF receptor activation resulted in TRAF3 degradation in a cIAP1-cIAP2-and TRAF2-dependent way due to enhanced cIAP1, cIAP2 TRAF3-directed ubiquitin ligase activity. Receptor-induced activation of cIAP1 and cIAP2 correlated with their K63-linked ubiquitination by TRAF2. Degradation of TRAF3 prevented association of NIK with the cIAP1-cIAP2-TRAF2 ubiquitin ligase complex, which resulted in NIK stabilization and NF-κB2-p100 processing. Constitutive activation of this pathway causes perinatal lethality and lymphoid defects.

Nature Immunology, 2010

A r t i c l e s AUTHoR conTRIBUTIons P.H.T. and M.K. planned and designed all experiments and wro... more A r t i c l e s AUTHoR conTRIBUTIons P.H.T. and M.K. planned and designed all experiments and wrote the manuscript; P.H.T. and A.M. did most experiments; W.Z. and T.M. helped with cell cultures, TRAF3 mutants and immunoprecipitation experiments; and D.A.A.V. provided the HWA4C4 K63specific antibody to ubiquitin.

Molecular Pharmacology, 2006

Although trastuzumab has been successfully used in patients with HER2-overexpressing metastatic b... more Although trastuzumab has been successfully used in patients with HER2-overexpressing metastatic breast cancer, resistance is a common problem that ultimately culminates in treatment failure. In light of the importance of Akt signaling in trastuzumab's antitumor action, we hypothesized that concurrent inhibition of Akt could enhance trastuzumab sensitivity and moreover reverse the resistant phenotype in HER2-positive breast cancer cells. Based on our finding that celecoxib mediates antitumor effects through the inhibition of phosphoinositide-dependent kinase-1 (PDK-1)/Akt signaling independently of cyclooxygenase-2 (COX-2), we used celecoxib as a scaffold to develop a COX-2-inactive PDK-1 inhibitor, 2-amino-N-[4-[5-(2-phenanthrenyl)-3-(trifluoromethyl)-1Hpyrazol-1-yl]phenyl]-acetamide (OSU-03012). Here, we investigated the effect of OSU-03012 on trastuzumab-mediated apoptosis in four breast cancer cell lines with different HER2 expression and trastuzumab-resistance status, including MDA-MB-231, BT474, SKBR3, and insulin-like growth factor-I receptoroverexpressing SKBR3 (SKBR3/IGF-IR). Effects of trastuzumab and OSU-03012, individually or in combination, on cell viability and changes in pertinent biomarkers including HER2 expression, phosphorylation of Akt, p27 kip1 , and the PDK-1 substrate p70 S6K were assessed. OSU-03012 alone was able to trigger apoptosis in all cell lines with equal potency (IC 50 ϭ 3-4 M), suggesting no cross-resistance with trastuzumab. Medium dose-effect analysis indicates that OSU-03012 potentiated trastuzumab's antiproliferative effect in HER2-positive cells, especially in SKBR3/IGF-IR cells, through the down-regulation of PDK-1/Akt signaling. This synergy, however, was not observed in HER2negative MDA-MB-231 cells. This combination treatment represents a novel strategy to increase the efficacy of trastuzumab and to overcome trastuzumab resistance in the treatment of HER2-positive breast cancer.

CancerSpectrum Knowledge Environment, 2002

The antitumor activity of cyclooxygenase-2 (COX-2) inhibitors is thought to involve COX-2 enzyme ... more The antitumor activity of cyclooxygenase-2 (COX-2) inhibitors is thought to involve COX-2 enzyme inhibition and apoptosis induction, but it is unclear whether COX-2 inhibition is required for apoptosis. Different COX-2 inhibitors have similar IC(50) values (concentration for 50% inhibition) for COX-2 inhibition but differ considerably in their abilities to induce apoptosis, suggesting the involvement of a COX-2-independent pathway in apoptosis. To test this hypothesis, we investigated the effect of COX-2 depletion on apoptosis and performed a structure-activity analysis of the COX-2 inhibitor celecoxib in the androgen-independent prostate cancer cell line PC-3. Tetracycline-inducible (Tet-On) COX-2 antisense clones were isolated to assess the effect of COX-2 expression on cell viability and sensitivity to apoptosis induced by COX-2 inhibitors. Untreated Tet-On clones differentially expressed COX-2, and doxycycline-treated clones were depleted of COX-2. We synthesized and characterized various celecoxib derivatives with various COX-2 inhibitory activities and determined their apoptotic activity in PC-3 cells. Apoptosis was assessed with four tests. In contrast to the effect of COX-2 inhibitors, which induced apoptosis, COX-2 depletion did not induce cell death. Susceptibility to COX-2 inhibitor-induced apoptosis was independent of the level of COX-2 expression. Structure-activity analysis found no correlation between apoptosis induction and COX-2 inhibition. Some celecoxib derivatives that lacked COX-2 inhibitory activity facilitated apoptosis and vice versa. Moreover, celecoxib and apoptosis-active celecoxib derivatives mediated cell death by inhibiting the same pathway. We have dissociated the apoptosis-inducing activity from the COX-2 inhibitory activity by structural modifications of the COX-2 inhibitor celecoxib. This separation of activities may provide a molecular basis for the development of new classes of apoptosis-inducing agents.

Journal of Cerebral Blood Flow & Metabolism, 2006

Prostacyclin (PGI 2 ), a potent vasodilator and inhibitor of platelet aggregation and leukocyte a... more Prostacyclin (PGI 2 ), a potent vasodilator and inhibitor of platelet aggregation and leukocyte activation, is crucial in vascular diseases such as stroke. Prostacyclin synthase (PGIS) is the key enzyme for PGI 2 synthesis. Although expression of PGIS was noted in the brain, its role in ischemic insult remains unclear. Here we reported the temporal and spatial expression of PGIS mRNA and protein after 60-min transient ischemia. Northern blot and in situ hybridization revealed a delayed increase of PGIS mRNA in the ischemic cortex at 24-to 72-h after ischemia; PGIS was detected mainly in the ipsilateral penumbra area, pyriform cortex, hippocampus, and leptomeninges. Western blot and immunohistochemical analysis revealed that PGIS proteins were expressed temporally and spatially similar to PGIS mRNA. PGIS was heavily colocalized with PECAM-1 to endothelial cells at the leptomeninges, large and small vessels, and localized to neuronal cells, largely at the penumbra area. A substantial amount of PGIS was also detected in the macrophage and glial cells. To evaluate its role against ischemic infarct, we overexpressed PGIS by adenoviral gene transfer. When infused 72 h before ischemia (À72 h), Adv-PGIS reduced infarct volume by B50%. However, it had no effect on infarct volume when infused immediately after ischemia (0 h). Eicosanoid analysis revealed selective elevation of PGI 2 at À72 h while PGI 2 and TXB 2 were both elevated at 0 h, altering the PGI 2 /thromboxane A 2 (TXA 2 ) ratio from 10 to 4. These findings indicate that PGIS protects the brain by enhancing PGI 2 synthesis and creating a favorable PGI 2 /TXA 2 ratio.

Journal of Biological Chemistry, 2003

Among various molecular strategies by which prostate cancer cells evade apoptosis, phosphoinositi... more Among various molecular strategies by which prostate cancer cells evade apoptosis, phosphoinositide 3-kinase (PI3K)/Akt signaling represents a dominant survival pathway. However, different prostate cancer cell lines such as LNCaP and PC-3 display differential sensitivity to the apoptotic effect of PI3K inhibition in serum-free media, reflecting the heterogeneous nature of prostate cancer in apoptosis regulation. Whereas both cell lines are equally susceptible to LY294002-mediated Akt dephosphorylation, only LNCaP cells default to apoptosis, as evidenced by DNA fragmentation and cytochrome c release. In PC-3 cells, Akt deactivation does not lead to cytochrome c release, suggesting that the intermediary signaling pathway is short-circuited by an antiapoptotic factor. This study presents evidence that Bcl-xL overexpression provides a distinct survival mechanism that protects PC-3 cells from apoptotic signals emanating from PI3K inhibition. First, the Bcl-xL/BAD ratio in PC-3 cells is at least an order of magnitude greater than that of LNCaP cells. Second, ectopic expression of Bcl-xL protects LNCaP cells against LY294002-induced apoptosis. Third, antisense down-regulation of Bcl-xL sensitizes PC-3 cells to the apoptotic effect of LY294002. The physiological relevance of this Bcl-xL-mediated survival mechanism is further underscored by the protective effect of serum on LY294002-induced cell death in LNCaP cells, which is correlated with a multifold increase in Bcl-xL expression. In contrast to Bcl-xL, Bcl-2 expression levels are similar in both cells lines, and do not respond to serum stimulation, suggesting that Bcl-2 may not play a physiological role in antagonizing apoptosis signals pertinent to BAD activation in prostate cancer cells.

Journal of Biological Chemistry, 2005

Despite advances in understanding the role of histone deacetylases (HDACs) in tumorigenesis, the ... more Despite advances in understanding the role of histone deacetylases (HDACs) in tumorigenesis, the mechanism by which HDAC inhibitors mediate antineoplastic effects remains elusive. Modifications of the histone code alone are not sufficient to account for the antitumor effect of HDAC inhibitors. The present study demonstrates a novel histone acetylation-independent mechanism by which HDAC inhibitors cause Akt dephosphorylation in U87MG glioblastoma and PC-3 prostate cancer cells by disrupting HDAC-protein phosphatase 1 (PP1) complexes. Of four HDAC inhibitors examined, trichostatin A (TSA) and HDAC42 exhibit the highest activity in down-regulating phospho-Akt, followed by suberoylanilide hydroxamic acid, whereas MS-275 shows only a marginal effect at 5 microm. This differential potency parallels the respective activities in inducing tubulin acetylation, a non-histone substrate for HDAC6. Evidence indicates that this Akt dephosphorylation is not mediated through deactivation of upstream kinases or activation of downstream phosphatases. However, the effect of TSA on phospho-Akt can be rescued by PP1 inhibition but not that of protein phosphatase 2A. Immunochemical analyses reveal that TSA blocks specific interactions of PP1 with HDACs 1 and 6, resulting in increased PP1-Akt association. Moreover, we used isozyme-specific small interfering RNAs to confirm the role of HDACs 1 and 6 as key mediators in facilitating Akt dephosphorylation. The selective action of HDAC inhibitors on HDAC-PP1 complexes represents the first example of modulating specific PP1 interactions by small molecule agents. From a clinical perspective, identification of this PP1-facilitated dephosphorylation mechanism underscores the potential use of HDAC inhibitors in lowering the apoptosis threshold for other therapeutic agents through Akt down-regulation.

Scientific reports, 2015

Molecular Cancer Therapeutics

PloS one, 2014

Neoplasia (New York, N.Y.), 2014

Chemico-biological interactions, Jan 25, 2015

Tetrahedron Letters, 2000

Science, 2008

Proceedings of the National Academy of Sciences, 2008

Nature Reviews Immunology, 2011

Nature Immunology, 2008

Nature Immunology, 2010

Molecular Pharmacology, 2006

CancerSpectrum Knowledge Environment, 2002

Journal of Cerebral Blood Flow & Metabolism, 2006

Journal of Biological Chemistry, 2003

Journal of Biological Chemistry, 2005