DPP3 promotes breast cancer tumorigenesis by stabilizing FASN and promoting lipid synthesis.

DPP3, a dipeptidyl peptidase, participates in a variety of pathophysiological processes. DPP3 is upregulated in cancer and might serve as a key factor in the tumorigenesis and progression of various malignancies. However, its specific role and molecular mechanism are still unknown. In this study, the expression of DPP3 in breast cancer tissues is analyzed using TCGA database. Kaplan-Meier survival analysis is performed to estimate the effect of DPP3 on the survival outcomes. To explore the biological function and mechanisms of DPP3 in breast cancer, biochemical and cell biology assays are conducted in vitro. DPP3 expresses at a higher level in breast cancer tissues than that in adjacent tissues in both TCGA database and clinical samples. Patients with high expression of DPP3 have poor survival outcomes. The proliferation and migration abilities of tumor cells with stable DPP3 knockout in breast cancer cell lines are significantly inhibited, and apoptosis is increased in vitro. GSEA analysis shows that DPP3 can affect lipid metabolism and fatty acid synthesis in tumors. Subsequent experiments show that DPP3 could stabilize FASN expression and thus promote fatty acid synthesis in tumor cells. The results of the metabolomic analysis also confirm that DPP3 can affect the content of free fatty acids. This study demonstrates that DPP3 plays a role in the reprogramming of fatty acid metabolism in tumors and is associated with poor prognosis in breast cancer patients. These findings will provide a new therapeutic target for the treatment of breast cancer.

Dipeptidyl-peptidase 9 regulates the dynamics of tumorigenesis and metastasis in breast cancer.

The cytosolic dipeptidyl-aminopeptidase 9 (DPP9) cleaves protein N-termini post-proline or -alanine. Our analysis of DPP9 mRNA expression from the TCGA 'breast cancer' data set revealed that low/intermediate DPP9 levels are associated with poor overall survival of breast cancer patients. To unravel the impact of DPP9 on breast cancer development and progression, the transgenic MMTV-PyMT mouse model of metastasizing breast cancer was used. In addition, tissue- and time-controlled genetic deletion of DPP9 by the Cre-loxP recombination system was done. Despite a delay of tumor onset, a higher number of lung metastases were measured in DPP9-deficient mice compared to controls. In human mammary epithelial cells with oncogenic RAS pathway activation, DPP9 deficiency delayed tumorigenic transformation and accelerated TGF-ß1 induced epithelial-to-mesenchymal transition (EMT) of spheroids. For further analysis of the mechanism, primary breast tumor cells were isolated from the MMTV-PyMT model. DPP9 deficiency in these cells caused cancer cell migration and invasion accompanied by EMT. In absence of DPP9, the EMT transcription factor ZEB1 was stabilized due to insufficient degradation by the proteasome. In summary, low expression of DPP9 appears to decelerate mammary tumorigenesis but favors EMT and metastasis, which establishes DPP9 as a novel dynamic regulator of breast cancer initiation and progression.

Saxagliptin, a selective dipeptidyl peptidase-4 inhibitor, alleviates somatic cell aneugenicity and clastogenicity in diabetic mice.

Diabetes-related complications are becoming increasingly common as the global prevalence of diabetes increases. Diabetes is also linked to a high risk of developing cancer. This raises the question of whether cancer vulnerability is caused by diabetes itself or the use of antidiabetic drugs. Chromosomal instability, a source of genetic modification involving either an altered chromosomal number or structure, is a hallmark of cancer. Saxagliptin has been approved by the FDA for diabetes treatment. However, the detailed in vivo effects of prolonged saxagliptin treatment on chromosomal instability have not yet been reported. In this study, streptozotocin was used to induce diabetes in mice, and both diabetic and non-diabetic mice received saxagliptin for five weeks. Fluorescence in situ hybridization was conducted in combination with a bone marrow micronucleus test for measuring chromosomal instability. Our results indicated that saxagliptin is neither mutagenic nor cytotoxic, under the given treatment regimen. Diabetic mice had a much higher incidence of micronuclei formation, and a centromeric DNA probe was present inside the majority of the induced micronuclei, indicating that most of these were caused by chromosome nondisjunction. Conversely, diabetic mice treated with saxagliptin exhibited a significant decrease in micronuclei induction, which were centromeric-positive and centromeric-negative. Diabetes also causes significant biochemical changes indicative of oxidative stress, such as increased lipid peroxidation and decreased reduced/oxidized glutathione ratio, which was reversed by saxagliptin administration. Overall, saxagliptin, the non-mutagenic antidiabetic drug, maintains chromosomal integrity in diabetes and reduces micronuclei formation by restoring redox imbalance, further indicating its usefulness in diabetic patients.

DPP9 Stabilizes NRF2 to Suppress Ferroptosis and Induce Sorafenib Resistance in Clear Cell Renal Cell Carcinoma.

The KEAP1-NRF2 axis is the principal regulator of cellular responses to oxidative and electrophilic stressors. NRF2 hyperactivation is frequently observed in many types of cancer and promotes cancer initiation, progression, metastasis, and resistance to various therapies. Here, we determined that dipeptidyl peptidase 9 (DPP9) is a regulator of the KEAP1-NRF2 pathway in clear cell renal cell carcinoma (ccRCC). DPP9 was markedly overexpressed at the mRNA and protein levels in ccRCC, and high DPP9 expression levels correlated with advanced tumor stage and poor prognosis in patients with ccRCC. Protein affinity purification to identify functional partners of DPP9 revealed that it bound to KEAP1 via a conserved ESGE motif. DPP9 disrupted KEAP1-NRF2 binding by competing with NRF2 for binding to KEAP1 in an enzyme-independent manner. Upregulation of DPP9 led to stabilization of NRF2, driving NRF2-dependent transcription and thereby decreasing cellular reactive oxygen species levels. Moreover, DPP9 overexpression suppressed ferroptosis and induced resistance to sorafenib in ccRCC cells, which was largely dependent on the NRF2 transcriptional target SLC7A11. Collectively, these findings indicate that the accumulation of DPP9 results in hyperactivation of the NRF2 pathway to promote tumorigenesis and intrinsic drug resistance in ccRCC. SIGNIFICANCE: DPP9 overcomes oxidative stress and suppresses ferroptosis in ccRCC by binding to KEAP1 and promoting NRF2 stability, which drives tumor development and sorafenib resistance.

The antiatherosclerotic action of 1G244 - An inhibitor of dipeptidyl peptidases 8/9 - is mediated by the induction of macrophage death.

BACKGROUND: Targeting cell death to induce favorable functional and morphological changes within atherosclerotic plaques has long been postulated as a promising anti-atherosclerotic strategy. In this regard, inhibition of dipeptidyl peptidases 8/9 has received special attention in the context of chronic inflammatory diseases due to its regulatory role in macrophage death in vivo. METHODS: The present study investigates the influence of prolonged treatment with 1G244 - an inhibitor of dipeptidyl peptidases 8/9 - on the development of the advanced atherosclerosis plaque in apoE-knockout mice, using morphometric and molecular methods. RESULTS: 1G244 administration has led to a reduction in atherosclerotic plaque size in an apoE-knockout mice model. Moreover, it reduced the content of in-plaque macrophages, attributed by immunohistochemical phenotyping to the pro-inflammatory M1-like activation state of these cells. Inhibition of dipeptidyl peptidases 8/9 augmented the lytic form of death response of activated macrophages in-vitro. CONCLUSIONS: In summary, inhibition of DPP 8/9 elicited an anti-atherosclerotic effect in apoE-/- mice, which can be attributed to the lytic form of death induction in activated macrophages, as assessed by the in vitro BMDM model. This, in turn, results in a reduction of the plaque area without its transformation towards a rupture-prone morphology.

Advance in dietary polyphenols as dipeptidyl peptidase-IV inhibitors to alleviate type 2 diabetes mellitus: aspects from structure-activity relationship and characterization methods.

Dietary polyphenols with great antidiabetic effects are the most abundant components in edible products. Dietary polyphenols have attracted attention as dipeptidyl peptidase-IV (DPP-IV) inhibitors and indirectly improve insulin secretion. The DPP-IV inhibitory activities of dietary polyphenols depend on their structural diversity. Screening methods that can be used to rapidly and accurately identify potential polyphenol DPP-IV inhibitors are urgently needed. This review focuses on the relationship between the structures of dietary polyphenols and their DPP-IV inhibitory effects. Different characterization methods used for polyphenols as DPP-IV inhibitors have been summarized and compared. We conclude that the position and number of hydroxyl groups, methoxy groups, glycosylated groups, and the extent of conjugation influence the efficiency of inhibition of DPP-IV. Various combinations of methods, such as in-vitro enzymatic inhibition, ex-vivo/in-vivo enzymatic inhibition, cell-based in situ, and in-silico virtual screening, are used to evaluate the DPP-IV inhibitory effects of dietary polyphenols. Further investigations of polyphenol DPP-IV inhibitors will improve the bioaccessibility and bioavailability of these bioactive compounds. Exploration of (i) dietary polyphenols derived from multiple targets, that can prevent diabetes, and (ii) actual binding interactions via multispectral analysis, to understand the binding interactions in the complexes, is required.

The emerging role of dipeptidyl peptidase 3 in pathophysiology.

Dipeptidyl peptidase 3 (DPP3), a zinc-dependent aminopeptidase, is a highly conserved enzyme among higher animals. The enzyme cleaves dipeptides from the N-terminus of tetra- to decapeptides, thereby taking part in activation as well as degradation of signalling peptides critical in physiological and pathological processes such as blood pressure regulation, nociception, inflammation and cancer. Besides its catalytic activity, DPP3 moonlights as a regulator of the cellular oxidative stress response pathway, e.g., the Keap1-Nrf2 mediated antioxidative response. The enzyme is also recognized as a key modulator of the renin-angiotensin system. Recently, DPP3 has been attracting growing attention within the scientific community, which has significantly augmented our knowledge of its physiological relevance. Herein, we review recent advances in our understanding of the structure and catalytic activity of DPP3, with a focus on attributing its molecular architecture and catalytic mechanism to its wide-ranging biological functions. We further highlight recent intriguing reports that implicate a broader role for DPP3 as a valuable biomarker in cardiovascular and renal pathologies and furthermore discuss its potential as a promising drug target.

Importance of Fibrosis in the Pathogenesis of Uterine Leiomyoma and the Promising Anti-fibrotic Effects of Dipeptidyl Peptidase-4 and Fibroblast Activation Protein Inhibitors in the Treatment of Uterine Leiomyoma.

Uterine fibroid or leiomyoma is the most common benign uterus tumor. The tumor is primarily composed of smooth muscle (fibroid) cells, myofibroblast, and a significant amount of extracellular matrix components. It mainly affects women of reproductive age. They are uncommon before menarche and usually disappear after menopause. The fibroids have excessive extracellular matrix components secreted by activated fibroblast cells (myofibroblast). Myofibroblast has the characteristics of fibroblast and smooth muscle cells. These cells possess contractile capability due to the expression of contractile proteins which are normally found only in muscle tissues. The rigid nature of the tumor is responsible for many side effects associated with uterine fibroids. The current drug treatment strategies are primarily hormone-driven and not anti-fibrotic. This paper emphasizes the fibrotic background of uterine fibroids and the mechanisms behind the deposition of excessive extracellular matrix components. The transforming growth factor-ß, hippo, and focal adhesion kinase-mediated signaling pathways activate the fibroblast cells and deposit excessive extracellular matrix materials. We also exemplify how dipeptidyl peptidase-4 and fibroblast activation protein inhibitors could be beneficial in reducing the fibrotic process in leiomyoma. Dipeptidyl peptidase-4 and fibroblast activation protein inhibitors prevent the fibrotic process in organs such as the kidneys, lungs, liver, and heart. These inhibitors are proven to inhibit the signaling pathways mentioned above at various stages of their activation. Based on literature evidence, we constructed a narrative review on the mechanisms that support the beneficial effects of dipeptidyl peptidase-4 and fibroblast activation protein inhibitors for treating uterine fibroids.

A Phenotypic Screen Identifies Potent DPP9 Inhibitors Capable of Killing HIV-1 Infected Cells.

Although current antiretroviral therapy can control HIV-1 replication and prevent disease progression, it is not curative. Identifying mechanisms that can lead to eradication of persistent viral reservoirs in people living with HIV-1 (PLWH) remains an outstanding challenge to achieving cure. Utilizing a phenotypic screen, we identified a novel chemical class capable of killing HIV-1 infected peripheral blood mononuclear cells. Tool compounds ICeD-1 and ICeD-2 ("inducer of cell death-1 and 2"), optimized for potency and selectivity from screening hits, were used to deconvolute the mechanism of action using a combination of chemoproteomic, biochemical, pharmacological, and genetic approaches. We determined that these compounds function by modulating dipeptidyl peptidase 9 (DPP9) and activating the caspase recruitment domain family member 8 (CARD8) inflammasome. Efficacy of ICeD-1 and ICeD-2 was dependent on HIV-1 protease activity and synergistic with efavirenz, which promotes premature activation of HIV-1 protease at high concentrations in infected cells. This in vitro synergy lowers the efficacious cell kill concentration of efavirenz to a clinically relevant dose at concentrations of ICeD-1 or ICeD-2 that do not result in complete DPP9 inhibition. These results suggest engagement of the pyroptotic pathway as a potential approach to eliminate HIV-1 infected cells.

Dipeptidylamino-tripeptidylcarboxypeptidase NEMP3 and DPP3 (DPP III) are the same protein.

Earlier it was shown that a group of extracellular low-specific metallopeptidases is present in the mammalian brain Kropotova and Mosevitsky (2016) [1]. These enzymes are weakly connected to the axonal ends of neurons. They were named Neuron bound Extracellular MetalloPeptidases (NEMP). The enzyme named NEMP3 turned out to be a unique exopeptidase that exhibits two activities: it removes the dipeptide from the N-end of the peptide, and it can also remove the tripeptide from the C-end of the peptide. Therefore, NEMP3 possesses the activities of dipeptidylaminopeptidase and of tripeptidylcarboxypeptidase. Mass spectrometry has revealed a homology of NEMP3 with DPP3 (DPP III, EC3.4.14.4), known as cytosolic dipeptidylaminopeptidase. We isolated DPP3 from rat and bovine liver and brain by the procedures used for this purpose by other authors. The effect of DPP3 on test peptides is the same as that of NEMP3. In particular, all DPP3 samples delete the tripeptide (AKF) from the C-end of the test peptide blocked at the N-end. The data obtained show that NEMP3 and DPP3 are the same protein (enzyme). Thus, DPP3 has two exopeptidase activities: the previously known activity of dipeptidylaminopeptidase and the activity of tripeptidylcarboxypeptidase discovered in this study. Another discovery is the extracellular activity of DPP 3 in the mammalian brain near synapses, which controls neuropeptides. DPP3 is involved in various processes, but in many cases its role remains to be clarified. The results obtained in this study will be useful for solving these questions.

A ubiquitin-independent proteasome pathway controls activation of the CARD8 inflammasome.

CARD8 is a pattern-recognition receptor that forms a caspase-1-activating inflammasome. CARD8 undergoes constitutive autoproteolysis, generating an N-terminal (NT) fragment with a disordered region and a ZU5 domain and a C-terminal (CT) fragment with UPA and CARD domains. Dipeptidyl peptidase 8 and dipeptidyl peptidase 9 inhibitors, including Val-boroPro, accelerate the degradation of the NT fragment via a poorly characterized proteasome-mediated pathway, thereby releasing the inflammatory CT fragment from autoinhibition. Here, we show that the core 20S proteasome, which degrades disordered and misfolded proteins independent of ubiquitin modification, controls activation of the CARD8 inflammasome. In unstressed cells, we discovered that the 20S proteasome degrades just the NT disordered region, leaving behind the folded ZU5, UPA, and CARD domains to act as an inhibitor of inflammasome assembly. However, in Val-boroPro-stressed cells, we show the 20S proteasome degrades the entire NT fragment, perhaps due to ZU5 domain unfolding, freeing the CT fragment from autoinhibition. Taken together, these results show that the susceptibility of the CARD8 NT domain to 20S proteasome-mediated degradation controls inflammasome activation.

Discovery of dipeptidyl peptidase-4 inhibitor specific biomarker in non-alcoholic fatty liver disease mouse models using modified basket trial.

BACKGROUND/AIMS: We aimed to define an optimal target population and drug-specific biomarkers that may predict dipeptidyl peptidase (DPP)-4 inhibitor responses in non-alcoholic fatty liver disease (NAFLD). METHODS: An exploration study (study I) was performed using three different NAFLD models (basket study design; high-fat diet [HFD], methionine choline-deficient diet [MCD], and high-cholesterol Western diet [WD] models). RNA transcriptome analysis was performed on pre-studied liver tissues to identify biomarkers that could predict the response to DPP-4 inhibitors. In the validation study (study II), the HFD-induced NAFLD model was divided into high and low hepatic insulin-like growth factor binding protein 1 (Igfbp-1) groups based on the pre-study liver biopsy. RESULTS: DPP-4 inhibitor attenuated the NAFLD activity score and fibrosis stage in the HFD model but not in the WD and MCD models. The overall response rate was 19% across the modified basket NAFLD trial and 42%, 25%, and 0% in the HFD, WD, and MCD models. Hepatic Igfbp-1 expression was higher in the responder group than in the non-responder group in pre-study biopsy samples. In contrast, hepatic Igfbp-1 expression was lower in the responder group than in the non-responder group in the end-study biopsy samples. DPP-4 inhibitor response rates were 83% and 17% in the baseline hepatic high Igfbp-1 and low Igfbp-1 groups, respectively. Hepatic messenger RNA Igfbp-1 expression was positively correlated with serum IGFBP-1 levels. CONCLUSION: The DPP-4 inhibitor response was higher in the HFD phenotype and pre-treatment levels of hepatic or serum IGFBP-1 were high.

Expanded substrate specificity supported by P1' and P2' residues enables bacterial dipeptidyl-peptidase 7 to degrade bioactive peptides.

Dipeptide production from extracellular proteins is crucial for Porphyromonas gingivalis, a pathogen related to chronic periodontitis, because its energy production is entirely dependent on the metabolism of amino acids predominantly incorporated as dipeptides. These dipeptides are produced by periplasmic dipeptidyl-peptidase (DPP)4, DPP5, DPP7, and DPP11. Although the substrate specificities of these four DPPs cover most amino acids at the penultimate position from the N terminus (P1), no DPP is known to cleave penultimate Gly, Ser, Thr, or His. Here, we report an expanded substrate preference of bacterial DPP7 that covers those residues. MALDI-TOF mass spectrometry analysis demonstrated that DPP7 efficiently degraded incretins and other gastrointestinal peptides, which were successively cleaved at every second residue, including Ala, Gly, Ser, and Gln, as well as authentic hydrophobic residues. Intravenous injection of DPP7 into mice orally administered glucose caused declines in plasma glucagon-like peptide-1 and insulin, accompanied by increased blood glucose levels. A newly developed coupled enzyme reaction system that uses synthetic fluorogenic peptides revealed that the P1' and P2' residues of substrates significantly elevated kcat values, providing an expanded substrate preference. This activity enhancement was most effective toward the substrates with nonfavorable but nonrepulsive P1 residues in DPP7. Enhancement of kcat by prime-side residues was also observed in DPP11 but not DPP4 and DPP5. Based on this expanded substrate specificity, we demonstrate that a combination of DPPs enables proteolytic liberation of all types of N-terminal dipeptides and ensures P. gingivalis growth and pathogenicity.

Dipeptidyl peptidase-8 induces sorafenib resistance via binding with c-Rel to mediate NF-κB signaling in hepatocellular carcinoma.

Sorafenib is the important first-standard drug for patients with advanced hepatocellular carcinoma (HCC). A major obstacle to successful treatment is sorafenib resistance. However, the mechanism of sorafenib resistance is unclear. The present study aimed to determine the involvement of dipeptidyl peptidase-8 (DPP8) in sorafenib resistance. DPP8 expression was detected using quantitative real-time PCR (qPCR) and western blot analysis. The effect of DPP8 on sorafenib resistance was examined using terminal deoxynulceotidyl transferase nick-end-labeling (TUNEL), colony formation, flow cytometry, luciferase reporter, immunofluorescence, and immunoprecipitation (IP) assays. We found that DPP8 mRNA and protein levels were dramatically upregulated in HCC. Gene set enrichment analysis (GSEA) illustrated that DPP8 might be involved in apoptosis regulation. Downregulation of DPP8 substantially promoted the sensitivity of HCC cells to sorafenib. Further analysis showed that DPP8 might regulate nuclear factor kappa B (NF-κB) signaling, which was confirmed using a luciferase reporter assay. Downregulation of DPP8 decreased the expression levels of downstream genes of the NF-κB pathway. IP showed that DPP8 can interact with NF-κB subunit c-Rel, an important protein of NF-κB signaling. Finally, a drug combination of sorafenib and Val-boroPro induced higher mortality of HCC cells than sorafenib alone in DPP8-upregulated cells. Our findings indicated that using the inhibitor Val-boroPro might be a promising method to enhance sorafenib sensitivity in advanced HCC.

Molecular Dynamics Simulations Study of the Interactions between Human Dipeptidyl-Peptidase III and Two Substrates.

Human dipeptidyl-peptidase III (hDPP III) is capable of specifically cleaving dipeptides from the N-terminal of small peptides with biological activity such as angiotensin II (Ang II, DRVYIHPF), and participates in blood pressure regulation, pain modulation, and the development of cancers in human biological activities. In this study, 500 ns molecular dynamics simulations were performed on free-hDPP III (PDB code: 5E33), hDPP III-Ang II (PDB code: 5E2Q), and hDPP III-IVYPW (PDB code: 5E3C) to explore how these two peptides affect the catalytic efficiency of enzymes in terms of the binding mode and the conformational changes. Our results indicate that in the case of the hDPP III-Ang II complex, subsite S1 became small and hydrophobic, which might be propitious for the nucleophile to attack the substrate. The structures of the most stable conformations of the three systems revealed that Arg421-Lys423 could form an α-helix with the presence of Ang II, but only part of the α-helix was produced in hDPP III-IVYPW. As the hinge structure in hDPP III, the conformational changes that took place in the Arg421-Lys423 residue could lead to the changes in the shape and space of the catalytic subsites, which might allow water to function as a nucleophile to attack the substrate. Our results may provide new clues to enable the design of new inhibitors for hDPP III in the future.

Dipeptidyl peptidase 9 sets a threshold for CARD8 inflammasome formation by sequestering its active C-terminal fragment.

CARD8 detects intracellular danger signals and forms a caspase-1 activating inflammasome. Like the related inflammasome sensor NLRP1, CARD8 autoprocesses into noncovalently associated N-terminal (NT) and C-terminal (CT) fragments and binds the cellular dipeptidyl peptidases DPP8 and 9 (DPP8/9). Certain danger-associated signals, including the DPP8/9 inhibitor Val-boroPro (VbP) and HIV protease, induce proteasome-mediated NT degradation and thereby liberate the inflammasome-forming CT. Here, we report cryoelectron microscopy (cryo-EM) structures of CARD8 bound to DPP9, revealing a repressive ternary complex consisting of DPP9, full-length CARD8, and CARD8-CT. Unlike NLRP1-CT, CARD8-CT does not interact with the DPP8/9 active site and is not directly displaced by VbP. However, larger DPP8/9 active-site probes can directly weaken this complex in vitro, and VbP itself nevertheless appears to disrupt this complex, perhaps indirectly, in cells. Thus, DPP8/9 inhibitors can activate the CARD8 inflammasome by promoting CARD8 NT degradation and by weakening ternary complex stability.

Profibrotic mechanisms of DPP8 and DPP9 highly expressed in the proximal renal tubule epithelial cells.

BACKGROUND: DPP8 and DPP9 have been demonstrated to play important roles in multiple diseases. Evidence for increased gene expression of DPP8 and DPP9 in tubulointerstitium was found to be associated with the decline of kidney function in chronic kidney disease (CKD) patients, which was observed in the Nephroseq human database. To examine the role of DPP8 and DPP9 in the tubulointerstitial injury, we determined the efficacy of DPP8 and DPP9 on epithelial-to-mesenchymal transition (EMT) and tubulointerstitial fibrosis (TIF) as well as the underlying mechanisms. METHODS: We conducted the immunofluorescence of DPP8 and DPP9 in kidney biopsy specimens of CKD patients, established unilateral ureteral obstruction (UUO) animal model, treated with TC-E5007 (a specific inhibitor of both DPP8 and DPP9) or Saxagliptin (positive control) or saline, and HK-2 cells model. RESULTS: We observed the significantly increased expression of DPP8 and DPP9 in the renal proximal tubule epithelial cells of CKD patients compared to the healthy control subjects. DPP8/DPP9 inhibitor TC-E5007 could significantly attenuate the EMT and extracellular matrix (ECM) synthesis in UUO mice, all these effects were mediated via interfering with the TGF-ß1/Smad signaling. TC-E5007 treatment also presented reduced renal inflammation and improved renal function in the UUO mice compared to the placebo-treated UUO group. Furthermore, the siRNA for DPP8 and DPP9, and TC-E5007 treatment decreased EMT- and ECM-related proteins in TGF-ß1-treated HK-2 cells respectively, which could be reversed significantly by transduction with lentivirus-DPP8 and lentivirus-DPP9. CONCLUSION: These data obtained provide evidence that the DPP8 and DPP9 could be potential therapeutic targets against TIF.

Harnessing affinity-based protein profiling to reveal a novel target of nintedanib.

Nintedanib (BIBF1120), a triple angiokinase inhibitor, was first approved for idiopathic pulmonary fibrosis (IPF) therapy and is also efficacious for lung carcinoma, and interstitial lung diseases, far beyond its inhibition of VEGFR/PDGFR/FGFR. We identified tripeptidyl-peptidase 1 (TPP1) as one of the direct targets of nintedanib employing the affinity-based protein profiling (AfBPP) technique. This may be a new mechanism for nintedanib's role different from tyrosine kinase inhibition.

Tripeptidyl peptidase I promotes human endometrial epithelial cell adhesive capacity implying a role in receptivity.

The endometrium undergoes cyclic remodelling throughout the menstrual cycle in preparation for embryo implantation which occurs in a short window during the mid-secretory phase. It is during this short 'receptive window' that the endometrial luminal epithelium acquires adhesive capacity permitting blastocysts firm adhesion to the endometrium to establish pregnancy. Dysregulation in any of these steps can compromise embryo implantation resulting in implantation failure and infertility. Many factors contribute to these processes including TGF-ß, LIF, IL-11 and proteases. Tripeptidyl peptidase 1 (TPP1) is a is a lysosomal serine-type protease however the contribution of the TPP1 to receptivity is unknown. We aimed to investigate the role of TPP1 in receptivity in humans.In the current study, TPP1 was expressed in both epithelial and stromal compartments of the endometrium across the menstrual cycle. Expression was confined to the cytoplasm of luminal and glandular epithelial cells and stromal cells. Staining of mid-secretory endometrial tissues of women with normal fertility and primary unexplained infertility showed reduced immunostaining intensity of TPP1 in luminal epithelial cells of infertile tissues compared to fertile tissues. By contrast, TPP1 levels in glandular epithelial and stromal cells were comparable in both groups in the mid-secretory phase. Inhibition of TPP1 using siRNA compromised HTR8/SVneo (trophoblast cell line) spheroid adhesion on siRNA-transfected Ishikawa cells (endometrial epithelial cell line) in vitro. This impairment was associated with decreased sirtuin 1 (SIRT1), BCL2 and p53 mRNA and unaltered, CD44, CDH1, CDH2, ITGB3, VEGF A, OSTEOPONTIN, MDM2, CASP4, MCL1, MMP2, ARF6, SGK1, HOXA-10, LIF, and LIF receptor gene expression between treatment groups. siRNA knockdown of TPP1 in primary human endometrial stromal cells did not affect decidualization nor the expression of decidualization markers prolactin (PRL) and insulin-like growth factor-binding protein 1 (IGFBP1). Taken together, our data strongly suggests a role for TPP1 in endometrial receptivity via its effects on epithelial cell adhesion and suggests reduced levels associated with unexplained infertility may contribute to implantation failure.

Beta Cell Imaging-From Pre-Clinical Validation to First in Man Testing.

There are presently no reliable ways to quantify human pancreatic beta cell mass (BCM) in vivo, which prevents an accurate understanding of the progressive beta cell loss in diabetes or following islet transplantation. Furthermore, the lack of beta cell imaging hampers the evaluation of the impact of new drugs aiming to prevent beta cell loss or to restore BCM in diabetes. We presently discuss the potential value of BCM determination as a cornerstone for individualized therapies in diabetes, describe the presently available probes for human BCM evaluation, and discuss our approach for the discovery of novel beta cell biomarkers, based on the determination of specific splice variants present in human beta cells. This has already led to the identification of DPP6 and FXYD2ga as two promising targets for human BCM imaging, and is followed by a discussion of potential safety issues, the role for radiochemistry in the improvement of BCM imaging, and concludes with an overview of the different steps from pre-clinical validation to a first-in-man trial for novel tracers.