d -Amino Acid-Based Protein Arginine Deiminase Inhibitors: Synthesis, Pharmacokinetics, and in Cellulo Efficacy

Liu

et al. 2016

Sci Rep

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Peptidylarginine deiminase (PADI) enzymes are increasingly being associated with the regulation of chromatin structure and gene activity via histone citrullination. As one of the PADI family members, PADI1 has been mainly reported to be expressed in the epidermis and uterus, where the protein in keratinocytes is thought to promote differentiation by citrullinating filament proteins. However, the roles of PADI1 in preimplantation development have not been addressed. Using a PADI1-specific inhibitor and Padi1-morpholino knockdown, we found that citrullination of histone tails at H4R3 and H3R2/8/17 were markedly reduced in the 2- and 4-cell embryos. Consistent with this observation, early embryo development was also arrested at the 4-cell stage upon depletion of PADI1 or inhibition of PADI1 enzyme activity. Additionally, by employing 5-ethynyl uridine (EU) incorporation analysis, ablation of PADI1 function led to a dramatic decrease in overall transcriptional activity, correlating well with the reduced levels of phosphorylation of RNA Pol II at Ser2 observed at 2- or 4-cell stage of embryos under Padi1 knockdown or inhibiting PADI1. Thus, our data reveal a novel function of PADI1 during early embryo development transitions by catalyzing histone tail citrullination, which facilitates early embryo genome transactivation.

Section: Resultsmentioning

confidence: 51%

Peptidylarginine deiminase 1-catalyzed histone citrullination is essential for early embryo development

Liu

et al. 2016

Sci Rep

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“…2G (bottom row). To help answer whether PAD1 enzymatic activity contributes to these biological phenotypes, we treated MDA-MB-231 cells with a newly developed arginine-based PAD1 inhibitor, D-Cl-amidine, which has been shown to effectively inhibit PAD1 activity in breast cancer cell lines [41]. Results showed that inhibiting PAD1 activity significantly inhibited cell proliferation (Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, novel anti-TNBC agents targeting tumor cell migration and invasion are urgently needed [54]. Our finding that PAD1 specific inhibitor, D-Cl-amidine, is successful in suppressing tumor growth in a xenograft mouse model of TNBC together with our previous in vitro study showing that D-Cl-amidine also effectively inhibits cell viability [41], suggests that inhibiting PAD1 could potentially be utilized as a good strategy to treat metastatic breast cancer. Further studies aimed at developing PAD1-selective inhibitors and then evaluating the pharmacokinetics, biodistribution, and anti-tumor effects of these compounds in preclinical models of cancer will represent important next steps towards advancing our overall goals.…”

Section: Discussionmentioning

confidence: 99%

PAD1 promotes epithelial-mesenchymal transition and metastasis in triple-negative breast cancer cells by regulating MEK1-ERK1/2-MMP2 signaling

Qin

Liu

et al. 2017

Cancer Letters

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Peptidylargininedeiminase 1 (PAD1) catalyzes protein for citrullination, and this activity has been linked to the epidermal cornification. However, a role for PAD1 in tumorigenesis, including breast cancers has not been previously explored. Here we first showed that PAD1 is overexpressed in human triple negative breast cancer (TNBC). In cultured cells and xenograft mouse models, PAD1 depletion or inhibition reduced cell proliferation, suppressed epithelial-mesenchymal transition, and prevented metastasis of MDA-MB-231 cells. These changes were correlated with a dramatic decrease in MMP2/9 expression. Furthermore, ERK1/2 and P38 MAPK signaling pathways are activated upon PAD1 silencing. Treatment with MEK1/2 inhibitor in PAD1 knockdown cells significantly recovered MMP2 expression, while inhibiting P38 activation only slightly elevated MMP9 levels. We then showed that PAD1 interacts with and citrullinates MEK1 thereby disrupting MEK1-catalyzed ERK1/2 phosphorylation, thus leading to the MMP2 overexpression. Collectively, our data indicate that PAD1 appears to promote tumorigenesis by regulating MEK1-ERK1/2-MMP2 signaling in TNBC. These results also raise the possibility that PAD1 may function as an important new biomarker for TNBC tumors and suggest that PAD1-specific inhibitors could potentially be utilized to treat metastatic breast cancer.

“…Inhibitor potency and selectivity were evaluated for PADs 1–4 24 25. Cell growth inhibition was evaluated by the XTT assay.…”

Section: Methodsmentioning

confidence: 99%

Peptidylarginine deiminase inhibition disrupts NET formation and protects against kidney, skin and vascular disease in lupus-prone MRL/lprmice

et al. 2014

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Objectives An imbalance between neutrophil extracellular trap (NET) formation and degradation has been described in systemic lupus erythematosus (SLE), potentially contributing to autoantigen externalisation, type I interferon synthesis and endothelial damage. We have demonstrated that peptidylarginine deiminase (PAD) inhibition reduces NET formation and protects against lupus-related vascular damage in the New Zealand Mixed model of lupus. However, another strategy for inhibiting NETs—knockout of NOX2—accelerates lupus in a different murine model, MRL/lpr. Here, we test the effects of PAD inhibition on MRL/lpr mice in order to clarify whether some NET inhibitory pathways may be consistently therapeutic across models of SLE. Methods NET formation and autoantibodies to NETs were characterised in lupus-prone MRL/lpr mice. MRL/lpr mice were also treated with two different PAD inhibitors, Cl-amidine and the newly described BB-Cl-amidine. NET formation, endothelial function, interferon signature, nephritis and skin disease were examined in treated mice. Results Neutrophils from MRL/lpr mice demonstrate accelerated NET formation compared with controls. MRL/lpr mice also form autoantibodies to NETs and have evidence of endothelial dysfunction. PAD inhibition markedly improves endothelial function, while downregulating the expression of type I interferon-regulated genes. PAD inhibition also reduces proteinuria and immune complex deposition in the kidneys, while protecting against skin disease. Conclusions PAD inhibition reduces NET formation, while protecting against lupus-related damage to the vasculature, kidneys and skin in various lupus models. The strategy by which NETs are inhibited will have to be carefully considered if human studies are to be undertaken.