Inhibition of circulating dipeptidyl peptidase 4 activity in patients with metastatic prostate cancer

Preparation, Characterization, and Antiangiogenic Evaluation of a Novel 5-Fluorouracil Derivative Solid Lipid Nanoparticle with a Hen's Egg Chorioallantoic Membrane Assay and Wound Healing Response in HaCaT Keratinocytes

5-Fluorouracil is a heterocyclic aromatic organic compound, and it is commonly used as a chemotherapeutic agent in many cancers. The present goal is to analyze and characterize the physicochemical and biological properties of a new therapeutic formulation of 5-FUD-Gal under simulated chronic wound and oxidative stress conditions. After synthesis of a new 5-fluorouracil derivative, preparation and characterization of the formulation were carried out. The antiangiogenic effect, wound healing, and oxidative stress responses were conducted with a HET-CAM assay and in vitro cell culture technique. The results initially demonstrated that 5-FUD-Gal synthesized by a series of reactions and the SLN formulation were prepared successfully. A strong cell protective effect above 98% cell viability was detected at 20 μM at 48 h. The wound closure of the HaCaT scratch assay was calculated to be 90.12 and 98.98% at 10 and 20 μM concentrations, respectively, at 48 h. Moreover, the strongest effect of 5-FUD-Gal-F was observed at 20 μM concentration on chicken embryos. This study provides novel insights that a new derivative of semisynthetic 5-FUD-Gal-F can be further evaluated as a therapeutic chemical compound in cancer disease.

Genetic variants of dipeptidyl peptidase IV are linked to the clinicopathologic development of prostate cancer

CD26/dipeptidyl peptidase IV (DPP4) is a multifunctional cell-surface glycoprotein widely found in many cell types, and a soluble form is present in body fluids. There is longstanding evidence indicating a tumour-promoting or -suppressive role of DPP4 in different cancer types. However, studies focusing on the impacts of genetic variants of DPP4 on cancers are very rare. Herein, we conducted a case-control study to evaluate whether single-nucleotide polymorphisms (SNPs) of DPP4 were associated with the risk or clinicopathologic development of prostate cancer (PCa). We genotyped four loci of DPP4 SNPs, including rs7608798 (A/G), rs3788979 (C/T), rs2268889 (T/C) and rs6741949 (G/C), using a TaqMan allelic discrimination assay in 704 PCa patients and 704 healthy controls. Our results showed that PCa patients with the DPP4 rs7608798 AG+GG genotype or rs2268889 TC+CC genotype had a higher risk of developing an advanced clinical primary tumour (cT) stage (adjusted odds ratio (AOR): 1.680, 95% confidence interval (CI): 1.062-2.659, p = 0.025; AOR: 1.693, 95% CI: 1.092-2.624, p = 0.018). Additionally, in The Cancer Genome Atlas (TCGA) database, we observed that lower DPP4 expression levels were correlated with higher Gleason scores, advanced cT and pathological stages, tumour metastasis, and shorter progression-free survival rates in PCa patients. Furthermore, overexpression of DPP4 suppressed migration/invasion of metastatic PC3 PCa cells. Our findings suggest that DPP4 levels may affect the progression of PCa, and the DPP4 rs7608798 and rs2268889 SNPs are associated with the clinicopathologic development of PCa in a Taiwanese population.

Liquid biopsy: the value of different bodily fluids

Liquid biopsies have gained an increasing interest in the last years among medical and scientific communities. Indeed, the value of liquid effusions, while less invasive and more accurate techniques, has been markedly highlighted. Peripheral blood comprises the most often analyzed sample, but recent evidences have pointed out the huge importance of other bodily fluids, including pleural and peritoneal fluids, urine, saliva and cerebrospinal fluid in the detection and monitoring of different tumor types. In face to these advances, this review aims to provide an overview of the value of tumor-associated mutations, detectable in different effusions, and how they can be used in clinical practice, namely in prognosis assessment and early disease and minimal disease recurrence detection, and in predicting the treatment response or acquired-resistance development.

An improved production and purification protocol for recombinant soluble human fibroblast activation protein alpha

Fibroblast activation protein alpha (FAP) is a cell-surface expressed type II glycoprotein that has a unique proteolytic activity. FAP has active soluble forms that retain the extracellular portion but lack the transmembrane domain and cytoplasmic tail. FAP expression is normally very low in adult tissue but is highly expressed by activated fibroblasts in sites of tissue remodelling. Thus, FAP is a potential biomarker and pharmacological target in liver fibrosis, atherosclerosis, cardiac fibrosis, arthritis and cancer. Understanding the biological significance of FAP by investigating protein structure, interactions and activities requires reliable methods for the production and purification of abundant pure and stable protein. We describe an improved production and purification protocol for His6-tagged recombinant soluble human FAP. A modified baculovirus expression construct was generated using the pFastBac1 vector and the gp67 secretion signal to produce abundant active soluble recombinant human FAP (residues 27-760) in insect cells. The FAP purification protocol employed ammonium sulphate precipitation, ion exchange chromatography, immobilised metal affinity chromatography and ultrafiltration. High purity was achieved, as judged by gel electrophoresis and specific activity. The purified 82 kDa FAP protein was specifically inhibited by a FAP selective inhibitor, ARI-3099, and was inhibited by zinc with an IC50 of 25 μM. Our approach could be adopted for producing the soluble portions of other type II transmembrane glycoproteins to study their structure and function.

The Influence of Anti-Diabetic Drugs on Prostate Cancer

The incidences of prostate cancer (PC) and diabetes are increasing, with a sustained trend. The occurrence of PC and type 2 diabetes mellitus (T2DM) is growing with aging. The correlation between PC occurrence and diabetes is noteworthy, as T2DM is correlated with a reduced risk of incidence of prostate cancer. Despite this reduction, diabetes mellitus increases the mortality in many cancer types, including prostate cancer. The treatment of T2DM is based on lifestyle changes and pharmacological management. Current available drugs, except insulin, are aimed at increasing insulin secretion (sulfonylureas, incretin drugs), improving insulin sensitivity (biguanides, thiazolidinediones), or increasing urinary glucose excretion (gliflozin). Comorbidities should be taken into consideration during the treatment of T2DM. This review describes currently known information about the mechanism and impact of commonly used antidiabetic drugs on the incidence and progression of PC. Outcomes of pre-clinical studies are briefly presented and their correlations with available clinical trials have also been observed. Available reports and meta-analyses demonstrate that most anti-diabetic drugs do not increase the risk during the treatment of patients with PC. However, some reports show a potential advantage of treatment of T2DM with specific drugs. Based on clinical reports, use of metformin should be considered as a therapeutic option. Moreover, anticancer properties of metformin were augmented while combined with GLP-1 analogs.

CD26/Dipeptidyl Peptidase IV and Its Multiple Biological Functions

CD26/Dipeptidyl peptidase IV (DPPIV) is a cell surface glycoprotein with numerous roles including glucose metabolism, immunomodulation, and tumorigenesis. CD26/DPPIV is well recognized in diabetes, with DPPIV inhibitors being a class of oral hypoglycemic drugs called gliptins that are commonly used to treat type two diabetes mellitus. Recent work also indicated a potential role for CD26 in infectious diseases, including COVID-19, and immune-mediated disorders such as rheumatoid arthritis, inflammatory bowel disease, and graft-versus-host disease.

In cancer, CD26/DPPIV expression has been characterized in numerous tumors such as hematologic malignancies, malignant pleural mesothelioma (MPM), renal cell carcinoma (RCC), hepatocellular carcinoma (HCC), gastrointestinal stromal tumor (GIST), and prostate, lung, colorectal, and ovarian (PLCO) cancer. Hence, CD26 has been frequently studied as a tumor biomarker and therapeutic target. CD26/DPPIV-targeted therapies have been evaluated in various cancers, including the use of anti-CD26 monoclonal antibodies as anticancer treatment in selected neoplasms.

This review highlights our current understanding of the role of CD26 in cancer, diabetes, immune-mediated diseases, and infectious diseases. Enhanced understanding of CD26 biology and function may lead to novel therapeutic approaches in multiple human diseases.

DPP4 Inhibitor Sitagliptin Enhances Lymphocyte Recruitment and Prolongs Survival in a Syngeneic Ovarian Cancer Mouse Model

Immunity plays a key role in epithelial ovarian cancer (EOC) progression with a well-documented correlation between patient survival and high intratumoral CD8+ to T regulatory cell (Treg) ratios. We previously identified dysregulated DPP4 activity in EOCs as a potentially immune-disruptive influence contributing to a reduction in CXCR3-mediated T-cell infiltration in solid tumours. We therefore hypothesized that inhibition of DPP4 activity by sitagliptin, an FDA-approved inhibitor, would improve T-cell infiltration and function in a syngeneic ID8 mouse model of EOC. Daily oral sitagliptin at 50 mg/kg was provided to mice with established primary EOCs. Sitagliptin treatment decreased metastatic tumour burden and significantly increased overall survival and was associated with significant changes to the immune landscape. Sitagliptin increased overall CXCR3-mediated CD8+ T-cell trafficking to the tumour and enhanced the activation and proliferation of CD8+ T-cells in tumour tissue and the peritoneal cavity. Substantial reductions in suppressive cytokines, including CCL2, CCL17, CCL22 and IL-10, were also noted and were associated with reduced CD4+ CD25+ Foxp3+ Treg recruitment in the tumour. Combination therapy with paclitaxel, however, typical of standard-of-care for patients in palliative care, abolished CXCR3-specific T-cell recruitment stimulated by sitagliptin. Our data suggest that sitagliptin may be suitable as an adjunct therapy for patients between chemotherapy cycles as a novel approach to enhance immunity, optimise T-cell-mediated function and improve overall survival.

Identification of predictors based on drug targets highlights accurate treatment of goserelin in breast and prostate cancer

Goserelin is an effective alternative to surgery or estrogen therapy in prostate cancer palliation, and possibly to ovariectomy in premenopausal breast cancer. However, not all users of goserelin can benefit from it, or some patients are not sensitive to goserelin. The advent of network pharmacology has highlighted the need for accurate treatment and predictive biomarkers. In this study, we successfully to identify 76 potential targets related to the compound of goserelin through network pharmacology approach. We also identified 18 DEGs in breast cancer tissues and 5 DEGs in cells, and 6 DEGs in prostate cancer tissues and 9 DEGs in cells. CRABP2 is the common DEG both in breast and prostate cancer. The risk prediction models constructed with potential prognostic targets of goserelin can successfully predict the prognosis in breast and prostate cancer, especially for very young breast cancer patients. Moreover, seven subgroups in breast cancer and six subgroups in prostate cancer were respectively identified based on consensus clustering using potential prognostic targets of goserelin that significantly influenced survival. The expression of representative genes including CORO1A and ANXA5 in breast and DPP4 in prostate showed strong correlations with clinic-pathological factors. Taken together, the novel signature can facilitate identification of new biomarkers which sensitive to goserelin, increase the using accuracy of goserelin and clarify the classification of disease molecular subtypes in breast and prostate cancer.

Glass Fiber-Supported Hybrid Monolithic Spin Tip for Enrichment of Phosphopeptides from Urinary Extracellular Vesicles

Extracellular vesicles (EVs) are attracting increasing interest with their intriguing role in intercellular communications. Protein phosphorylation in EVs is of great importance for understanding intercellular signaling processes. However, the study of EV phosphoproteomics is impeded by their relatively low amount in limited clinical sample volumes, and it is necessary to have a sensitive and efficient enrichment method for EV phosphopeptides. Herein, a novel Ti(IV)-functionalized and glass fiber-supported hybrid monolithic spin tip, termed PhosTip, was prepared for enriching phosphopeptides from urinary EVs. Glass fiber as the stationary phase positions the hybrid monolith in a standard pipet tip and prevents the monolith from distortion during experiments. The preparation procedure for the new PhosTip is simple and time-saving. The hybrid monolithic PhosTip provides excellent enrichment efficiency of low-abundance phosphopeptides from cell digests and urinary EVs with minimum contamination and sample loss. Using the PhosTip, we demonstrate that 5373 and 336 unique phosphopeptides were identified from 100 and 1 μg of cell lysates, while 3919 and 217 unique phosphopeptides were successfully identified from 10 and 1 mL of urinary samples, respectively. The PhosTip was finally applied to enrich phosphopeptides in urine EVs from prostate cancer patients and healthy controls and quantify 118 up-regulated proteins with phosphosites in prostate cancer samples. These results demonstrated that the PhosTip could be a simple and convenient tool for enriching phosphopeptides from clinical samples and for broader applications in biomarker discovery.

Angiogenesis is promoted by exosomal DPP4 derived from 5-fluorouracil-resistant colon cancer cells

Cancer cells can communicate with the tumor microenvironment and contribute to tumor progression. However, the effects of drug-resistant tumor cells on angiogenesis are unclear. Current anti-angiogenic strategies also have limitations and it would be useful to develop novel targets and treatment strategies. Here, our study showed that the conditioned medium and exosomes from 5-FU-resistant colon cancer cells promoted angiogenesis, and we observed that exosomal dipeptidyl peptidase IV (DPP4) was a potent inducer of this angiogenesis. DPP4-enriched exosomes increased periostin (POSTN) expression in human umbilical vein endothelial cells via Twist1 nuclear translocation or activating Smad signaling pathway, while silencing or inhibition of DPP4 neutralized those effects. The in vivo and clinical data indicated that high DPP4 expression was related to tumor progression. These findings indicate that DPP4 may be a target for inhibiting angiogenesis in 5-FU-resistant colon cancer. Furthermore, exosomal DPP4 concentrations may be a useful prognostic marker for colon cancer.

Discovery of a putative blood-based protein signature associated with response to ALK tyrosine kinase inhibition

Background

ALK tyrosine kinase inhibition has become a mainstay in the clinical management of ALK fusion positive NSCLC patients. Although ALK mutations can reliably predict the likelihood of response to ALK tyrosine kinase inhibitors (TKIs) such as crizotinib, they cannot reliably predict response duration or intrinsic/extrinsic therapeutic resistance. To further refine the application of personalized medicine in this indication, this study aimed to identify prognostic proteomic biomarkers in ALK fusion positive NSCLC patients to crizotinib.

Methods

Twenty-four patients with advanced NSCLC harboring ALK fusion were administered crizotinib in a phase IV trial which included blood sampling prior to treatment. Targeted proteomics of 327 proteins using MRM-MS was used to measure plasma levels at baseline (including pre-treatment and early treatment blood samples) and assess potential clinical association.

Results

Patients were categorized by duration of response: long-term responders [PFS ≥ 24 months (n = 7)], normal responders [3 < PFS < 24 months (n = 10)] and poor responders [PFS ≤ 3 months (n = 5)]. Several proteins were identified as differentially expressed between long-term responders and poor responders, including DPP4, KIT and LUM. Next, using machine learning algorithms, we evaluated the classification potential of 40 proteins. Finally, by integrating the different analytic methods, we selected 22 proteins as potential candidates for a blood-based prognostic signature of response to crizotinib in NSCLC patients harboring ALK fusion.

Conclusion

In conjunction with ALK mutation, the expression of this proteomic signature may represent a liquid biopsy-based marker of long-term response to crizotinib in NSCLC. Expanding the utility of prognostic biomarkers of response duration could influence choice of therapy, therapeutic sequencing, and potentially the need for alternative or combination therapy.Trial registration ClinicalTrials.gov, NCT02041468. Registered 22 January 2014, https://clinicaltrials.gov/ct2/show/NCT02041468?term=NCT02041468&rank=1.

CD26-Related Serum Biomarkers: sCD26 Protein, DPP4 Activity, and Anti-CD26 Isotype Levels in a Colorectal Cancer-Screening Context

Current screening trials are showing reduction in colorectal cancer incidence and mortality. However, participation rates are often low, and blood-based tests could complement existing screening strategies. CD26 protein (sCD26) and its dipeptidyl peptidase IV (DPP4) enzymatic activity in circulation have been proposed as biomarkers for colorectal cancer and other diseases. However, changes in sCD26 and DPP4 levels show complex degrees of correlation, and their physiological or pathophysiological role is unclear. The aim of this study was to analyse if anti-CD26 autoantibodies are related to sCD26 and DPP4 and to determine their relevance in a context of colorectal cancer screening for complementing the value of sCD26 and DPP4 as biomarkers. These biomarkers were measured in a large prospective cohort (n = 497, except the anti-CD26 antibodies, evaluated in 125 samples) that included a subgroup of individuals that were positive for the faecal immunological occult blood test (FIT) (n = 86) and underwent a colonoscopy (n = 47). We confirmed for the first time higher DPP4 activity in men compared to women (Student's t test, p = 0.002), though this difference between sexes was not seen for serum sCD26 protein. These biomarkers correlated (R = 0.246, p = 0.003) only in women. Correlations were found between anti-CD26 isotypes but not with DPP4 activity or sCD26 concentration, except for a negative correlation only in men between anti-CD26 IgA isotype and sCD26 (R = -0.232, p = 0.044), and an almost significant negative correlation between anti-CD26 IgG and sCD26 limited to FIT-positive men. Interestingly, patients with advanced adenomas displayed the most elevated mean levels of anti-CD26 IgA, IgM, and particularly IgG (Mann-Whitney U test, p = 0.030) in comparison with the other FIT positives without adenomas, and these levels did not correlate with sCD26 or its DPP4 activity. Our preliminary results suggest that the combination of these measures using sex as confounder could perhaps be used as biomarkers for colorectal disease. It also suggests that events affecting the gut influence the levels of anti-CD26 antibodies, which show little or no effect in antigen clearance. These findings should be confirmed in a larger cohort of individuals with colonoscopy. The physiological origin of the sex differences observed should be further addressed.

CD26/DPP4 - a potential biomarker and target for cancer therapy

CD26/dipeptidyl peptidase (DPP)4 is a membrane-bound protein found in many cell types of the body, and a soluble form is present in body fluids. There is longstanding evidence that various primary tumors and also metastases express CD26/DPP4 to a variable extent. By cleaving dipeptides from peptides with a proline or alanine in the penultimate position at the N-terminus, it regulates the activity of incretin hormones, chemokines and many other peptides. Due to these effects and interactions with other molecules, a tumor promoting or suppressing role can be attributed to CD26/DPP4. In this review, we discuss the existing evidence on the expression of soluble or membrane-bound CD26/DPP4 in malignant diseases, along with the most recent findings on CD26/DPP4 as a therapeutic target in specific malignancies. The expression and possible involvement of the related DPP8 and DPP9 in cancer are also reviewed. A higher expression of CD26/DPP4 is found in a wide variety of tumor entities, however more research on CD26/DPP4 in the tumor microenvironment is needed to fully explore its use as a tumor biomarker. Circulating soluble CD26/DPP4 has also been studied as a cancer biomarker, however, the observed decrease in most cancer patients does not seem to be cancer specific. Encouraging results from experimental work and a recently reported first phase clinical trial targeting CD26/DPP4 in mesothelioma, renal and urological tumors pave the way for follow-up clinical studies, also in other tumor entities, possibly leading to the development of more effective complementary therapies against cancer.

Predictive significance of serum dipeptidyl peptidase-IV in papillary thyroid carcinoma

BACKGROUND

The significance of serum dipeptidyl peptidase-IV (DPP-IV) in papillary thyroid carcinoma (PTC) has not been elucidated.

OBJECTIVE

This study aimed to assess the role of serum DPP-IV in the carcinogenesis and prognosis of PTC.

METHODS

The serum DPP-IV concentration was measured in 171 male patients with PTC, 81 male patients with a benign thyroid nodule (BTN), and 52 male healthy controls (HCs). Multivariate logistic regression and Cox regression analyses were performed to evaluate the correlations between variables. Receiver operating characteristic (ROC) curves were used to calculate the diagnosis accuracy.

RESULTS

The ROC curve indicated a good performance of DPP-IV for discriminating PTC from BTN, with an area under the curve (AUC) of 0.881 (95% CI, 0.840-0.922). Serum DPP-IV demonstrated a modest performance in predicting nonstructurally persistent disease/recurrent disease (NSPRD) survival, with an AUC of 0.778 (95% CI, 0.635-0.922). A serum DPP-IV level ⩾ 250 nkat/L (HR, 6.529; 95% CI, 2.090-20.398; P= 0.001) and an advanced tumor, lymph node, metastasis (TNM) stage (HR, 4.677; 95% CI, 1.498-14.605; P= 0.008) were found to be independent factors for predicting SPRD. PTC patients with a DPP-IV level ⩾ 250 nkat/L had a worse outcome than those with a DPP-IV level < 250 nkat/L (P< 0.001).

CONCLUSIONS

Serum DPP-IV may be a predictive biomarker for PTC diagnosis and prognosis in Chinese male patients.

Downregulation of Dipeptidyl Peptidase 4 Accelerates Progression to Castration-Resistant Prostate Cancer

The standard treatment for metastatic prostate cancer, androgen deprivation therapy (ADT), is designed to suppress androgen receptor (AR) activity. However, men invariably progress to castration-resistant prostate cancer (CRPC), and AR reactivation contributes to progression in most cases. To identify mechanisms that may drive CRPC, we examined a VCaP prostate cancer xenograft model as tumors progressed from initial androgen sensitivity prior to castration to castration resistance and then on to relapse after combined therapy with further AR-targeted drugs (abiraterone plus enzalutamide). AR activity persisted in castration-resistant and abiraterone/enzalutamide-resistant xenografts and was associated with increased expression of the AR gene and the AR-V7 splice variant. We then assessed expression of individual AR-regulated genes to identify those that persisted, thereby contributing to tumor growth, versus those that decreased and may therefore exhibit tumor suppressor activities. The most significantly decreased AR target gene was dipeptidyl peptidase 4 (DPP4), which encodes a membrane-anchored protein that cleaves dipeptides from multiple growth factors, resulting in their increased degradation. DPP4 mRNA and protein were also decreased in clinical CRPC cases, and inhibition of DPP4 with sitagliptin enhanced the growth of prostate cancer xenografts following castration. Significantly, DPP4 inhibitors are frequently used to treat type 2 diabetes as they increase insulin secretion. Together, these results implicate DPP4 as an AR-regulated tumor suppressor gene whose loss enhances growth factor activity and suggest that treatment with DPP4 inhibitors may accelerate emergence of resistance to ADT.Significance: These findings identify DPP4 as an AR-stimulated tumor suppressor gene that is downregulated during progression to castration-resistant prostate cancer, warning that treatment with DPP4 inhibitors, commonly used to treat type 2 diabetes, may accelerate prostate cancer progression following androgen deprivation therapy. Cancer Res; 78(22); 6354-62. ©2018 AACR.

Obesity parameters, physical activity, and physical fitness are correlated with serum dipeptidyl peptidase IV activity in a healthy population

Objective

To determine whether obesity, physical fitness, and physical activity parameters are associated with the enzymatic activity of serum dipeptidyl peptidase IV (sDPPIV) in a sample of healthy women and men.

Design and methods

We have correlated parameters of obesity, physical fitness, and physical activity with sDPPIV activity in 374 healthy subjects (age: 60.7 ± 6.9 years, body mass index: 26.1 ± 4.1 kg/m²). Enzymatic activity was analyzed using spectrofluorimetry, body composition was assessed by impedanciometry, physical fitness data were obtained using the Senior Fitness Test, and physical activity data were collected by accelerometer. Pearson's partial correlation analysis was applied to determine the relationship between DPPIV activity and the rest of parameters and significantly correlated variables were introduced into linear regression models to predict DPPIV.

Results

Serum DPPIV activity was negatively associated with obesity parameters such as body mass (r = -0.112), body mass index (BMI) (r = -0.147), waist circumference (r = -0.164), waist-to-hip ratio (-0.104), and percentage of fat mass (r = -0.185). Serum DPPIV activity was positively associated with cardiovascular fitness (r = 0.138), total amount of physical activity (r = 0.153), and time spent doing light exercise (r = 0.184). Regression models revealed sex differences in enzyme activity with overall activity higher in women than in men (β = 0.437, p < 0.001). Further, percent fat mass was an independent negative predictor of DPPIV activity (β = -0.184, p = 0.001). Serum DPPIV activity was positively predicted based on the amount of time spent doing light physical activity (β = 0.167, p = 0.001).

Conclusion

Our results demonstrate that sDPPIV activity is positively associated with healthier parameters regarding fatness, fitness and physical activity.

A DNA-assisted immunoassay for enzyme activity via a DNA-linked, activity-based probe

Here, we describe an immunoassay approach for the detection of enzyme activity by quantitative PCR (qPCR) or parallel DNA sequencing which relies on activity-based probes linked to barcoding DNAs. We demonstrate this technique in the detection of serine hydrolase activities using a fluorophosphonate-oligonucleotide conjugate.

Hepatocyte-secreted DPP4 in obesity promotes adipose inflammation and insulin resistance

Obesity-induced metabolic disease involves functional integration among several organs via circulating factors, but little is known about crosstalk between liver and visceral adipose tissue (VAT). In obesity, VAT becomes populated with inflammatory adipose tissue macrophages (ATMs). In obese humans, there is a close correlation between adipose tissue inflammation and insulin resistance, and in obese mice, blocking systemic or ATM inflammation improves insulin sensitivity. However, processes that promote pathological adipose tissue inflammation in obesity are incompletely understood. Here we show that obesity in mice stimulates hepatocytes to synthesize and secrete dipeptidyl peptidase 4 (DPP4), which acts with plasma factor Xa to inflame ATMs. Silencing expression of DPP4 in hepatocytes suppresses inflammation of VAT and insulin resistance; however, a similar effect is not seen with the orally administered DPP4 inhibitor sitagliptin. Inflammation and insulin resistance are also suppressed by silencing expression of caveolin-1 or PAR2 in ATMs; these proteins mediate the actions of DPP4 and factor Xa, respectively. Thus, hepatocyte DPP4 promotes VAT inflammation and insulin resistance in obesity, and targeting this pathway may have metabolic benefits that are distinct from those observed with oral DPP4 inhibitors.

Sitagliptin may reduce prostate cancer risk in male patients with type 2 diabetes

This retrospective cohort study evaluated the risk of prostate cancer associated with sitagliptin use in Taiwanese male patients with type 2 diabetes mellitus by using the reimbursement databases of the National Health Insurance. Male patients with newly diagnosed type 2 diabetes mellitus at an age ≥25 years between 1999 and 2010 were recruited. A total of 37,924 ever users of sitagliptin and 426,276 never users were followed until December 31, 2011. The treatment effect of sitagliptin (for ever versus never users, and for tertiles of cumulative duration of therapy) was estimated by Cox regression incorporated with the inverse probability of treatment weighting using propensity score. Analyses were also conducted in a 1:1 matched pair cohort based on 8 digits of propensity score. Results showed that during follow-up, 84 ever users and 2,549 never users were diagnosed of prostate cancer, representing an incidence of 140.74 and 240.17 per 100,000 person-years, respectively. The hazard ratio (95% confidence intervals) for ever users versus never users was 0.613 (0.493-0.763). The respective hazard ratio for the first, second, and third tertile of cumulative duration of sitagliptin use <5.9, 5.9-12.7 and >12.7 months was 0.853 (0.601-1.210), 0.840 (0.598-1.179) and 0.304 (0.191-0.483), respectively; and was 0.856 (0.603-1.214), 0.695 (0.475-1.016) and 0.410 (0.277-0.608) for cumulative dose <15,000, 15,000-33,600 and >33,600 mg, respectively. Findings were supported by analyses in the matched cohort. In conclusion, sitagliptin significantly reduces the risk of prostate cancer, especially when the cumulative duration is >12.7 months or the cumulative dose >33,600 mg.

Discovery of Cell-Type-Specific and Disease-Related Enzymatic Activity Changes via Global Evaluation of Peptide Metabolism

Cellular homeostasis is maintained by a complex network of reactions catalyzed by enormous numbers of enzymatic activities (the enzymome), which serve to determine the phenotypes of cells. Here, we focused on the enzymomics of proteases and peptidases because these enzymes are an important class of disease-related proteins. We describe a system that (A) simultaneously evaluates metabolic activities of peptides using a series of exogenous peptide substrates and (B) identifies the enzymes that metabolize the specified peptide substrate with high throughput. We confirmed that the developed system was able to discover cell-type-specific and disease-related exo- and endopeptidase activities and identify the responsible enzymes. For example, we found that the activity of the endopeptidase neurolysin is highly elevated in human colorectal tumor tissue samples. This simple but powerful enzymomics platform should be widely applicable to uncover cell-type-specific reactions and altered enzymatic functions with potential value as biomarkers or drug targets in various disease states and to investigate the mechanisms of the underlying pathologies.

Prognostic Utility of a New mRNA Expression Signature of Gleason Score

PURPOSE

Gleason score strongly predicts prostate cancer mortality; however, scoring varies among pathologists, and many men are diagnosed with intermediate-risk Gleason score 7. We previously developed a 157-gene signature for Gleason score using a limited gene panel. Using a new whole-transcriptome expression dataset, we verified the previous signature's performance and developed a new Gleason signature to improve lethal outcome prediction among men with Gleason score 7.

EXPERIMENTAL DESIGN

We generated mRNA expression data from prostate tumor tissue from men in the Physicians' Health Study and Health Professionals Follow-Up Study (N = 404) using the Affymetrix Human Gene 1.0 ST microarray. The Prediction Analysis for Microarrays method was used to develop a signature to distinguish high (≥8) versus low (≤6) Gleason score. We evaluated the signature's ability to improve prediction of lethality among men with Gleason score 7, adjusting for 3 + 4/4 + 3 status, by quantifying the area under the receiver operating characteristic (ROC) curve (AUC).

RESULTS

We identified a 30-gene signature that best distinguished Gleason score ≤6 from ≥8. The AUC to predict lethal disease among Gleason score 7 men was 0.76 [95% confidence interval (CI), 0.67-0.84] compared with 0.68 (95% CI, 0.59-0.76) using 3 + 4/4 + 3 status alone (P = 0.0001). This signature was a nonsignificant (P = 0.09) improvement over our previous signature (AUC = 0.72).

CONCLUSIONS

Our new 30-gene signature improved prediction of lethality among men with Gleason score 7. This signature can potentially become a useful prognostic tool for physicians to improve treatment decision making. Clin Cancer Res; 23(1); 81-87. ©2016 AACRSee related commentary by Yin et al., p. 6.

Increased Plasma Dipeptidyl Peptidase-4 Activities in Patients with Coronary Artery Disease

Dipeptidyl peptidase-4 (DPP4) is one of the most potent mammalian serine proteases participated in the pathogenesis of subclinical atherosclerosis. Here we investigated whether the plasma soluble form of DPP4 is associated with the prevalence of coronary artery disease (CAD) with and without diabetes mellitus (DM). A cross-sectional study was conducted of 496 aged 26–81 years with (n = 362) and without (n = 134) CAD. Plasma DPP4 activity, high sensitive C-reactive protein (hs-CRP), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein levels were measured. The coronary atherosclerotic plaques were evaluated by coronary angiography. The CAD patients with (n = 84) and without (n = 278) DM had significantly higher DPP4 levels (11.8 ± 3.1 vs. 6.9 ± 3.5 ng/mL, P<0.01) than the nonCAD subjects. The acute coronary syndrome patients (n = 299) had elevated DPP4 levels than those with stable angina patients (n = 83). CAD patients even without DM had increased plasma DPP4 activities as compared with nonCAD subjects (10.9 ± 4.9 vs. 6.4 ± 3.1, ng/L, P< 0.01). A linear regression analysis revealed that overall, the DPP4 levels were positively associated with LCL-C and hs-CRP levels as well as syntax scores. A multiple logistic regression analysis demonstrated that plasma DPP4 activity was independent predictor of CAD (odds ratio, 1.56; 95% CI, 1.19–1.73; P<0.01). Our study shows that increased DPP4 activity levels are associated with the presence of CAD and that the plasma DPP4 level serves as a novel biomarker for CAD even without DM.

Dipeptidyl-peptidase IV activity is correlated with colorectal cancer prognosis

Background

Dipeptidyl-peptidase IV (EC 3.4.14.5) (DPPIV) is a serine peptidase involved in cell differentiation, adhesion, immune modulation and apoptosis, functions that control neoplastic transformation. Previous studies have demonstrated altered expression and activity of tissue and circulating DPPIV in several cancers and proposed its potential usefulness for early diagnosis in colorectal cancer (CRC).

Methods and principal findings

The activity and mRNA and protein expression of DPPIV was prospectively analyzed in adenocarcinomas, adenomas, uninvolved colorectal mucosa and plasma from 116 CRC patients by fluorimetric, quantitative RT-PCR and immunohistochemical methods. Results were correlated with the most important classic pathological data related to aggressiveness and with 5-year survival rates. Results showed that: 1) mRNA levels and activity of DPPIV increased in colorectal neoplasms (Kruskal-Wallis test, p<0.01); 2) Both adenomas and CRCs displayed positive cytoplasmic immunostaining with luminal membrane reinforcement; 3) Plasmatic DPPIV activity was lower in CRC patients than in healthy subjects (Mann-U test, p<0.01); 4) Plasmatic DPPIV activity was associated with worse overall and disease-free survivals (log-rank p<0.01, Cox analysis p<0.01).

Conclusion/significance

1) Up-regulation of DPPIV in colorectal tumors suggests a role for this enzyme in the neoplastic transformation of colorectal tissues. This finding opens the possibility for new therapeutic targets in these patients. 2) Plasmatic DPPIV is an independent prognostic factor in survival of CRC patients. The determination of DPPIV activity levels in the plasma may be a safe, minimally invasive and inexpensive way to define the aggressiveness of CRC in daily practice.