Browsing by Author "Zeng, Li-Fan"

Now showing 1 - 6 of 6
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    Abnormal PTPN11 enhancer methylation promotes rheumatoid arthritis fibroblast-like synoviocyte aggressiveness and joint inflammation
    (American Society for Clinical Investigation, 2016-05-19) Maeshima, Keisuke; Stanford, Stephanie M.; Hammaker, Deepa; Sacchetti, Cristiano; Zeng, Li-Fan; Ai, Rizi; Zhang, Vida; Boyle, David L.; Aleman Muench, German R.; Feng, Gen-Sheng; Whitaker, John W.; Zhang, Zhong-Yin; Wang, Wei; Bottini, Nunzio; Firestein, Gary S.; Department of Biochemistry & Molecular Biology, IU School of Medicine
    The PTPN11 gene, encoding the tyrosine phosphatase SHP-2, is overexpressed in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) compared with osteoarthritis (OA) FLS and promotes RA FLS invasiveness. Here, we explored the molecular basis for PTPN11 overexpression in RA FLS and the role of SHP-2 in RA pathogenesis. Using computational methods, we identified a putative enhancer in PTPN11 intron 1, which contained a glucocorticoid receptor- binding (GR-binding) motif. This region displayed enhancer function in RA FLS and contained 2 hypermethylation sites in RA compared with OA FLS. RA FLS stimulation with the glucocorticoid dexamethasone induced GR binding to the enhancer and PTPN11 expression. Glucocorticoid responsiveness of PTPN11 was significantly higher in RA FLS than OA FLS and required the differentially methylated CpGs for full enhancer function. SHP-2 expression was enriched in the RA synovial lining, and heterozygous Ptpn11 deletion in radioresistant or innate immune cells attenuated K/BxN serum transfer arthritis in mice. Treatment with SHP-2 inhibitor 11a-1 reduced RA FLS migration and responsiveness to TNF and IL-1β stimulation and reduced arthritis severity in mice. Our findings demonstrate how abnormal epigenetic regulation of a pathogenic gene determines FLS behavior and demonstrate that targeting SHP-2 or the SHP-2 pathway could be a therapeutic strategy for RA.
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    Exploring the Existing Drug Space for Novel pTyr Mimetic and SHP2 Inhibitors
    (American Chemical Society, 2015-07-09) He, Rongjun; Yu, Zhi-Hong; Zhang, Ruo-Yu; Wu, Li; Gunawan, Andrea M.; Lane, Brandon S.; Shim, Joong S.; Zeng, Li-Fan; He, Yantao; Chen, Lan; Wells, Clark D.; Liu, Jun O.; Zhang, Zhong-Yin; Department of Biochemistry & Molecular Biology, IU School of Medicine
    Protein tyrosine phosphatases (PTPs) are potential therapeutic targets for many diseases. Unfortunately, despite considerable drug discovery efforts devoted to PTPs, obtaining selective and cell permeable PTP inhibitors remains highly challenging. We describe a strategy to explore the existing drug space for previously unknown PTP inhibitory activities. This led to the discovery of cefsulodin as an inhibitor of SHP2, an oncogenic phosphatase in the PTP family. Crystal structure analysis of SHP2 interaction with cefsulodin identified sulfophenyl acetic amide (SPAA) as a novel phosphotyrosine (pTyr) mimetic. A structure-guided and SPAA fragment-based focused library approach produced several potent and selective SHP2 inhibitors. Notably, these inhibitors blocked SHP2-mediated signaling events and proliferation in several cancer cell lines. Thus, SPAA may serve as a new platform for developing chemical probes for other PTPs.
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    Hydroxyindole carboxylic acid-based inhibitors for receptor-type protein tyrosine protein phosphatase beta
    (Mary Ann Liebert, Inc., 2014-05-10) Zeng, Li-Fan; Zhang, Ruo-Yu; Bai, Yunpeng; Wu, Li; Zhang, Zhong-Yin; Department of Biochemistry & Molecular Biology, IU School of Medicine
    AIMS: Protein tyrosine phosphatases (PTPs) play an important role in regulating a wide range of cellular processes. Understanding the role of PTPs within these processes has been hampered by a lack of potent and selective PTP inhibitors. Generating potent and selective probes for PTPs remains a significant challenge because of the highly conserved and positively charged PTP active site that also harbors a redox-sensitive Cys residue. RESULTS: We describe a facile method that uses an appropriate hydroxyindole carboxylic acid to anchor the inhibitor to the PTP active site and relies on the secondary binding elements introduced through an amide-focused library to enhance binding affinity for the target PTP and to impart selectivity against off-target phosphatases. Here, we disclose a novel series of hydroxyindole carboxylic acid-based inhibitors for receptor-type tyrosine protein phosphatase beta (RPTPβ), a potential target that is implicated in blood vessel development. The representative RPTPβ inhibitor 8b-1 (L87B44) has an IC50 of 0.38 μM and at least 14-fold selectivity for RPTPβ over a large panel of PTPs. Moreover, 8b-1 also exhibits excellent cellular activity and augments growth factor signaling in HEK293, MDA-MB-468, and human umbilical vein endothelial cells. INNOVATION: The bicyclic salicylic acid pharmacophore-based focused library approach may provide a potential solution to overcome the bioavailability issue that has plagued the PTP drug discovery field for many years. CONCLUSION: A novel method is described for the development of bioavailable PTP inhibitors that utilizes bicyclic salicylic acid to anchor the inhibitors to the active site and peripheral site interactions to enhance binding affinity and selectivity.
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    Inhibition of SHP2 ameliorates the pathogenesis of systemic lupus erythematosus
    (American Society for Clinical Investigation, 2016-06-01) Wang, Jianxun; Mizui, Masayuki; Zeng, Li-Fan; Bronson, Roderick; Finnell, Michele; Terhorst, Cox; Kyttaris, Vasileios C.; Tsokos, George C.; Zhang, Zhong-Yin; Kontaridis, Maria I.; Department of Biochemistry & Molecular Biology, IU School of Medicine
    Systemic lupus erythematosus (SLE) is a devastating multisystemic autoimmune disorder. However, the molecular mechanisms underlying its pathogenesis remain elusive. Some patients with Noonan syndrome, a congenital disorder predominantly caused by gain-of-function mutations in the protein tyrosine phosphatase SH2 domain–containing PTP (SHP2), have been shown to develop SLE, suggesting a functional correlation between phosphatase activity and systemic autoimmunity. To test this directly, we measured SHP2 activity in spleen lysates isolated from lupus-prone MRL/lpr mice and found it was markedly increased compared with that in control mice. Similar increases in SHP2 activity were seen in peripheral blood mononuclear cells isolated from lupus patients relative to healthy patients. To determine whether SHP2 alters autoimmunity and related immunopathology, we treated MRL/lpr mice with an SHP2 inhibitor and found increased life span, suppressed crescentic glomerulonephritis, reduced spleen size, and diminished skin lesions. SHP2 inhibition also reduced numbers of double-negative T cells, normalized ERK/MAPK signaling, and decreased production of IFN-γ and IL-17A/F, 2 cytokines involved in SLE-associated organ damage. Moreover, in cultured human lupus T cells, SHP2 inhibition reduced proliferation and decreased production of IFN-γ and IL-17A/F, further implicating SHP2 in lupus-associated immunopathology. Taken together, these data identify SHP2 as a critical regulator of SLE pathogenesis and suggest targeting of its activity as a potent treatment for lupus patients.
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    Novel anticancer agents based on targeting the trimer interface of the PRL phosphatase
    (AACR Publications, 2016-08-15) Bai, Yunpeng; Yu, Zhi-Hong; Liu, Sijiu; Zhang, Lujuan; Zhang, Ruo-Yu; Zeng, Li-Fan; Zhang, Sheng; Zhang, Zhong-Yin; Biochemistry and Molecular Biology, School of Medicine
    PRL oncoproteins are phosphatases overexpressed in numerous types of human cancer. Elevated levels of PRL associate with metastasis and poor clinical outcomes. In principle, PRL phosphatases offer appealing therapeutic targets, but they remain underexplored due to the lack of specific chemical probes. In this study, we address this issue by exploiting a unique property of PRL phosphatases, namely, that they may function as homotrimers. Starting from a sequential structure-based virtual screening and medicinal chemistry strategy, we identified Cmpd-43 and several analogs which disrupt PRL1 trimerization. Biochemical and structural analyses demonstrate that Cmpd-43 and its close analogs directly bind the PRL1 trimer interface and obstruct PRL1 trimerization. Cmpd-43 also specifically blocks the PRL1-induced cell proliferation and migration through attenuation of both ERK1/2 and Akt activity. Importantly, Cmpd-43 exerted potent anticancer activity both in vitro and in vivo in a murine xenograft model of melanoma. Our results validate a trimerization-dependent signaling mechanism for PRL and offer proof-of-concept for trimerization inhibitors as candidate therapeutics to treat PRL-driven cancers
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    Therapeutic Potential of Targeting the Oncogenic SHP2 Phosphatase
    (American Chemical Society, 2014-08-14) Zeng, Li-Fan; Zhang, Ruo-Yu; Yu, Zhi-Hong; Li, Sijiu; Wu, Li; Gunawan, Andrea M.; Lane, Brandon S.; Mali, Raghuveer S.; Li, Xingjun; Chan, Rebecca J.; Kapur, Reuben; Wells, Clark D.; Zhang, Zhong-Yin; Department of Biochemistry & Molecular Biology, IU School of Medicine
    , The Src homology 2 domain containing protein tyrosine phosphatase-2 (SHP2) is an oncogenic phosphatase associated with various kinds of leukemia and solid tumors. Thus, there is substantial interest in developing SHP2 inhibitors as potential anticancer and antileukemia agents. Using a structure-guided and fragment-based library approach, we identified a novel hydroxyindole carboxylic acid-based SHP2 inhibitor 11a-1, with an IC50 value of 200 nM and greater than 5-fold selectivity against 20 mammalian PTPs. Structural and modeling studies reveal that the hydroxyindole carboxylic acid anchors the inhibitor to the SHP2 active site, while interactions of the oxalamide linker and the phenylthiophene tail with residues in the β5–β6 loop contribute to 11a-1’s binding potency and selectivity. Evidence suggests that 11a-1 specifically attenuates the SHP2-dependent signaling inside the cell. Moreover, 11a-1 blocks growth factor mediated Erk1/2 and Akt activation and exhibits excellent antiproliferative activity in lung cancer and breast cancer as well as leukemia cell lines.