Dipeptidyl-peptidase IV activity is correlated with colorectal cancer prognosis

Soluble DPP4 can act as a diagnostic biomarker in Hashimoto's thyroiditis with thyroid papillary carcinoma

Background

Hashimoto's thyroiditis (HT) is an independent risk factor for papillary thyroid carcinoma (PTC), but the underlying mechanism remains unknown. The incidence of PTC in patients with HT is significantly elevated, and the presence of both HT and PTC contributes to a higher rate of misdiagnosis.

Materials and Methods

Gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed on the thyroid nodule gene chip dataset from GEO Datasets. Serum and clinical data from 191 patients with thyroid nodules at the affiliated hospital were collected for analysis. Experimental techniques, including real-time quantitative PCR, ELISA, immunohistochemistry (IHC), and enzyme activity detection, were used to measure the level of dipeptidyl peptidase 4 (DPP4) in thyroid nodule tissues and serum.

Results

Thyroid nodules in patients with HT and PTC exhibit high levels of DPP4, along with elevated concentrations of soluble DPP4 in the serum. These findings demonstrate the potential predictive value of soluble DPP4 for PTC diagnosis.

Conclusions

The concentration and enzymatic activity of soluble DPP4 in serum can serve as diagnostic biomarkers for patients with HT-associated PTC.

Evaluation of Blood Soluble CD26 as a Complementary Biomarker for Colorectal Cancer Screening Programs

Fecal hemoglobin immunodetection (FIT) in combination with endoscopy has been implemented to reduce mortality from colorectal cancer (CRC), although there are issues that can be improved in relation to participation rates. We studied whether the blood biomarker soluble-CD26 (sCD26), related at least in part to the immune system and inflammation, and/or its dipeptidyl peptidase enzyme activity (DPP4), could help reduce false positives. In a cohort of 1703 individuals who underwent colonoscopy and had a serum sample, sCD26 and DPP4 activity showed statistically significant differences regarding sex and age. According to the colonoscopy findings, sCD26 and DPP4 activity progressively decreased in advanced adenomas and CRC, with statistically significant differences, even between both groups; 918 of them had a FIT result (n = 596 positive cases) with approximately 70% of these (n = 412) false positives. With cut-offs of 440 ng/mL for sCD26, 42 mU/mL for DPP4, and 11 ng/mU for their ratio, the combined information of the three biomarkers (at least positive for one biomarker) identified almost all advanced adenomas and CRC cases in the FIT cohort with approximately half of the false positives compared to FIT. A sequential testing strategy with FIT and our blood biomarker test is proposed.

Does DPP-IV Inhibition Offer New Avenues for Therapeutic Intervention in Malignant Disease?

Simple Summary

There is growing interest in identifying the effects of antidiabetic agents on cancer risk, progression, and anti-cancer treatment due to the long-term use of these medications and the inherently increased risk of malignancies in diabetic patients. Tumor development and progression are affected by multiple mediators in the tumor microenvironment, several of which may be proteolytically modified by the multifunctional protease dipeptidyl peptidase-IV (DPP-IV, CD26). Currently, low-molecular-weight DPP-IV inhibitors (gliptins) are used in patients with type 2 diabetes based on the observation that DPP-IV inhibition enhances insulin secretion by increasing the bioavailability of incretins. However, the DPP-IV-mediated cleavage of other biopeptides and chemokines is also prevented by gliptins. The potential utility of gliptins in other areas of medicine, including cancer, is therefore being evaluated. Here, we critically review the existing evidence on the role of DPP-IV inhibitors in cancer pathogenesis, their potential to be used in anti-cancer treatment, and the possible perils associated with this approach.

Abstract

Dipeptidyl peptidase IV (DPP-IV, CD26) is frequently dysregulated in cancer and plays an important role in regulating multiple bioactive peptides with the potential to influence cancer progression and the recruitment of immune cells. Therefore, it represents a potential contributing factor to cancer pathogenesis and an attractive therapeutic target. Specific DPP-IV inhibitors (gliptins) are currently used in patients with type 2 diabetes mellitus to promote insulin secretion by prolonging the activity of the incretins glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Nevertheless, the modulation of the bioavailability and function of other DPP-IV substrates, including chemokines, raises the possibility that the use of these orally administered drugs with favorable side-effect profiles might be extended beyond the treatment of hyperglycemia. In this review, we critically examine the possible utilization of DPP-IV inhibition in cancer prevention and various aspects of cancer treatment and discuss the potential perils associated with the inhibition of DPP-IV in cancer. The current literature is summarized regarding the possible chemopreventive and cytotoxic effects of gliptins and their potential utility in modulating the anti-tumor immune response, enhancing hematopoietic stem cell transplantation, preventing acute graft-versus-host disease, and alleviating the side-effects of conventional anti-tumor treatments.

A Pilot Study Investigating the Expression Levels of Pluripotency-Associated Genes in Rectal Swab Samples for Colorectal Polyp and Cancer Diagnosis and Prognosis

Change in gene expression is inevitable in cancer development. With more studies demonstrating the contributions of cancer stem cells (CSCs) in colorectal cancer (CRC) development, this study is aimed at investigating whether rectal swab specimen serves as a tool for detection of dysregulation of CSC or stem cell (SC) markers and at evaluating its potential as a new promising screening method for high-risk patients. Expression levels of 15 pluripotency-associated genes were assessed by quantitative PCR in 53 rectal swab specimens referred for endoscopic screening. Dysregulated genes and joint panels based on such genes were examined for their diagnostic potentials for both polyp and CRC. Out of 15 genes, Oct4, CD26, c-MYC, and CXCR4 showed significantly differential expression among normal, polyp, and CRC patients. A panel of Oct4 and CD26 showed an AUC value of 0.80 (p = 0.003) in identifying CRC patients from polyp/normal subjects, with sensitivity and specificity of 84.6% and 69.2%. A panel of c-MYC and CXCR4 achieved CRC/polyp identification with an AUC value of 0.79 (p = 0.002), with a sensitivity of 82.8% and specificity of 80.0%. The sensitivity for polyp and CRC was 80.0% and 85.7%, respectively. Further analysis showed that higher c-MYC and CXCR4 level was detected in normal subjects who developed polyps after 5-6 years, in comparison with subjects with no lesion developed, and the AUC of the c-MYC and CXCR4 panel increased to 0.88 (p < 0.001), with sensitivity and specificity of 84.4% and 92.3%, respectively, when these patients were included in the polyp group. This study suggests that the Oct4 and CD26 panel is a promising biomarker for distinguishing CRC from normal and polyp patients, whereas the c-MYC and CXCR4 panel may identify polyp and CRC from normal individuals.

Repurposing DPP-4 Inhibitors for Colorectal Cancer: A Retrospective and Single Center Study

Simple Summary

Colorectal cancer is one of the most common causes and the leading cause of cancer deaths worldwide. Its poor prognosis highlights the urgent need for more effective treatments. Repurposing approved drugs is a promising strategy as preclinical screenings can be minimized. The aim of our retrospective study was to investigate the potential of Dipeptidyl-peptidase 4 (DPP4)-inhibitors, which are safe Food and Drug Association (FDA)-approved drugs for treating diabetes, in treating CRC patients. Our findings conclude that CRC patients with diabetes and treated with DPP4-inhibitors in our hospital during 2006–2015, their 5-year prognosis following curative resection was significantly better than those treated with metformin. We further showed that their prognosis was associated with immune cell population features that associated with better prognosis, and immune cell profile is a biomarker for predicting the prognosis of DPP4-inhibitors treated CRC patients.

Abstract

Background: There have been studies reporting the crucial roles of Dipeptidyl-peptidase 4 (DPP4) in colorectal cancer (CRC) initiation and progression, whereas DPP4-inhibitors are safe Food and Drug Association (FDA)-approved drugs for treating diabetes. This study aims to investigate the association between DPP4-inhibitor treatment and the prognosis of CRC patients. Methods: Clinical data of CRC patients with diabetes and the prescription of DPP4-inhibitors who had undergone curative surgery in our hospital between January 2006 and December 2015 were retrieved. Their survival data and immune cell population in circulatory blood were compared to those treated with metformin. Results: The DPP4-inhibitor patient group showed a significantly better 5-year disease-free survival (median DFS = 1733 days, 95% CI = 1596 to 1870 days) when compared to the metformin group (p = 0.030, median DFS = 1382 days, 95% CI = 1246 to 1518 days). 33 out of the 92 patients in the metformin group showed recurrence whereas only 3 of the 26 patients in the DPP4-inhibitor group showed recurrence (p = 0.033). Cox regression analysis demonstrated that DPP4-inhibitor application is a favorable factor associated with a lower risk of recurrence (Hazard ratio = 0.200, p = 0.035). Furthermore, our results suggested that the immune cell profile of CRC patients is a potential biomarker for response to DPP4-inhibitor treatment. Conclusion: This study demonstrated the association of DPP4-inhibitor treatment with a better prognosis of CRC patients.

Serum soluble CD26/DPP4 titer variation is a potential prognostic biomarker in cancer therapy with a humanized anti-CD26 antibody

Background

The phase I trial of the humanized anti-CD26 monoclonal antibody YS110 for CD26-expressing tumors was conducted recently. The present study identifies a potential prognostic biomarker for CD26-targeted therapy based on the phase I data.

Methods

Box and Whisker plot analysis, Scatter plot analysis, Peason product moment correlation/Spearman’s rank-difference correlation, Bar graph analysis, and Receiver Operating Characteristics (ROC) were used to examine the correlation between sCD26 titer variation with YS110 administration and tumor volume change, RECIST criteria evaluation and progression free survival (PFS). Mechanism for serum sCD26 titer variation was confirmed by in vitro experimentation.

Results

Serum sCD26/DPP4 titer was reduced following YS110 administration and gradually recovered until the next infusion. Serum sCD26/DPP4 titer before the next infusion was sustained at lower levels in Stable Disease (SD) cases compared to Progressive Disease cases. ROC analysis defined the cut-off level of serum sCD26/DPP4 titer variation at day 29 pre/post for the clinical outcome of SD as tumor response or PFS. In vitro experimentation confirmed that YS110 addition reduced sCD26 production from CD26-expressing tumor and non-tumor cells.

Conclusions

Our study indicates that serum sCD26/DPP4 titer variation in the early phase of YS110 treatment is a predictive biomarker for evaluating therapeutic efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-021-00273-0.

The mechanism of sitagliptin inhibition of colorectal cancer cell lines' metastatic functionalities

The cell membrane glycoprotein CD26 with peptidase activity (DPP4) and/or its soluble CD26/DPP4 counterpart expression and/or activity are altered in several cancers. Its role in metastasis development was recently highlighted by the discovery of CD26⁺ cancer stem cell subsets and the fact that clinical DPP4 inhibitors showed antimetastatic effects in animal models. Also, diabetic patients treated with the DPP4 inhibitor sitagliptin showed greater overall survival after colorectal or lung cancer surgery than patients under other diabetic therapies. However, the mechanism of action of these inhibitors in this context is unclear. We studied the role of CD26 and its DPP4 enzymatic activity in malignant cell features such as cell-to-cell homotypic aggregation, cancer cell motility, and invasion in a panel of human colorectal cancer (CRC) cell lines, avoiding models that include the physiological role of DPP4 in chemotaxis. Present results indicate that CD26 participates in the induction of cell invasion, motility, and aggregation of CD26-positive CRC cell lines. Moreover, only invasion and motility assays, which are collagen matrix-dependent, showed a decrease upon treatment with the DPP4 inhibitor sitagliptin. Sitagliptin showed opposite effects to those of transforming growth factor-β1 on epithelial-to-mesenchymal transition and cell cycle, but this result does not explain its CD26/DPP4-dependent effect. These results contribute to the elucidation of the molecular mechanisms behind sitagliptin inhibition of metastatic traits. At the same time, this role of sitagliptin may help to define areas of medicine where DPP4 inhibitors might be introduced. However, they also suggest that additional tools against CD26 as a target might be used or developed for metastasis prevention in addition to gliptins.

Fecal Dipeptidyl Peptidase-4: An Emergent Biomarker in Inflammatory Bowel Disease

INTRODUCTION

Dipeptidyl peptidase-4 (DPP-4) is a membrane-bound glycoprotein that acts as a receptor but also exists in a soluble form. It has been recognized as a mediator of inflammation and considered a biomarker in inflammatory bowel disease (IBD).

METHODS

We evaluated a prospectively recruited cohort, consisting of 101 patients with IBD, using validated clinical indexes; 22 patients with ulcerative colitis (UC) underwent endoscopic evaluation. Fecal DPP-4 (fDPP-4) levels were analyzed and correlated with clinical scores, Mayo endoscopic score (in UC patients), serum DPP-4, C-reactive protein, and fecal calprotectin. Immunohistochemical staining for DPP-4 in intestinal biopsies was also performed.

RESULTS

When compared with remitters, median fDPP-4 levels were higher in patients with ileal Crohn's disease (CD) (7,584 [1,464-7,816] vs 2,104 [630-2,676] ng/mL, P = 0.015) and lower in patients with UC exhibiting clinical activity (1,213 [559-1,682] vs 7,814 [2,555-7,985] ng/mL, P < 0.001). Patients with UC presenting endoscopic activity also had lower levels than remitters (939 [559-1,420] vs 7,544 [4,531-7,940] ng/mL, P = 0.006). Fecal DPP-4 discriminated clinical activity from remission with areas under the curve of 0.76 (95% confidence interval [CI] 0.58-0.94, P = 0.015) and 0.80 (95% CI 0.68-0.93, P < 0.001) in CD and UC, respectively; it allowed to differentiate endoscopic activity in patients with UC, with areas under the curve of 0.84 (95% CI 0.63-1.00, P = 0.009). Immunohistochemical analysis revealed higher DPP-4 apical expression in UC remitters, but no statistically significant differences were revealed between patients with ileal CD.

DISCUSSION

Our results suggest that fDPP-4 can be used as a biomarker of IBD activity, particularly in UC. The expression profiles in intestinal tissue might represent a functional compartmentalization of DPP-4 expression.

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.

Hypoxia Regulates DPP4 Expression, Proteolytic Inactivation, and Shedding from Ovarian Cancer Cells

The treatment of ovarian cancer has not significantly changed in decades and it remains one of the most lethal malignancies in women. The serine protease dipeptidyl peptidase 4 (DPP4) plays key roles in metabolism and immunity, and its expression has been associated with either pro- or anti-tumour effects in multiple tumour types. In this study, we provide the first evidence that DPP4 expression and enzyme activity are uncoupled under hypoxic conditions in ovarian cancer cells. Whilst we identified strong up-regulation of DPP4 mRNA expression under hypoxic growth, the specific activity of secreted DPP4 was paradoxically decreased. Further investigation revealed matrix metalloproteinases (MMP)-dependent inactivation and proteolytic shedding of DPP4 from the cell surface, mediated by at least MMP10 and MMP13. This is the first report of uncoupled DPP4 expression and activity in ovarian cancer cells, and suggests a previously unrecognized, cell- and tissue-type-dependent mechanism for the regulation of DPP4 in solid tumours. Further studies are necessary to identify the functional consequences of DPP4 processing and its potential prognostic or therapeutic value.

Soluble cluster of differentiation 26/soluble dipeptidyl peptidase-4 and glypican-3 are promising serum biomarkers for the early detection of Hepatitis C virus related hepatocellular carcinoma in Egyptians

BACKGROUND AND STUDY AIMS

Many patients are diagnosed with hepatocellular carcinoma (HCC) in the late stage when it is already untreatable. Therefore, there is an increased need for sensitive biomarkers to detect HCC at an earlier stage in high risk patients with hepatitis C virus (HCV)-induced cirrhosis. This study aimed to evaluate the diagnostic performance of soluble cluster of differentiation 26/dipeptidyl peptidase 4 (sCD26/sDPP4) and glypican-3 (GPC3) as serum biomarkers for the early detection of HCV related HCC and compare it with that of the conventional tumor marker serum alpha fetoprotein (AFP).

PATIENTS AND METHODS

The study included 80 participants, 30 patients diagnosed with HCV infection without HCC (HCV group), 30 patients diagnosed with HCV- related HCC (HCV group), and 20 healthy volunteers (control group). The serum levels of GPC3 and sCD26 were measured using specific enzyme linked immunosorbant assay (ELISA) kits, whereas AFP levels were determined using chemiluminescence.

RESULTS

The serum levels of both sCD26 and GPC3 were found to be significantly higher in patients with early-stage HCC than in the HCV group, (1450 and 1.16 ng/mL, respectively). sCD26 at a cutoff value of > 1000 ng/ml, showed a high sensitivity (83.3%) and 63.3% specificity with an area under curve (AUC) of 0.811 and a 95% confidence interval (CI) of (0.682-0.94). While, the combination of GPC3 and sCD26 exhibited the best diagnostic performance for early-stage-HCC because it increased the sensitivity and specificity (85% and 93.3% respectively), with an AUC of 0.986 and a 95% CI of (0.899-1.00) compared to sCD26 alone.

CONCLUSION

We conclude that serum sCD26 could be a sensitive biomarker for the early detection of HCC among HCV patients. Moreover, the combination of sCD26 and GPC3 increases both the sensitivity and specificity for the early detection of HCV related HCC compared with AFP and could help in the monitoring of HCC in high risk patients with HCV induced cirrhosis.

Effects of novel antidiabetes agents on apoptotic processes in diabetes and malignancy: Implications for lowering tissue damage

Apoptosis is a complicated process that involves activation of a series of intracellular signaling. Tissue injuries from diabetes mellitus mostly occur as a consequence of higher rate of apoptosis process due to activation of a series of molecular mechanisms. Several classes of anti-hyperglycaemic agents have been developed which could potentially modulate the apoptotic process resulting in fewer tissue damages. Novel types of anti-hyperglycaemic medications such as sodium glucose cotransporters-2 inhibitors, glucagon like peptide-1 receptor agonists and dipeptidyl peptidase 4 inhibitors have shown to provide potent anti-hyperglycaemic effects, but their influences on diabetes-induced apoptotic injuries is largely unknown. Therefore, in the current study, we reviewed the published data about the possible effects of these anti-hyperglycaemic agents on apoptosis in diabetic milieu as well as in cancer cells.

Diagnostic and prognostic significance of serum CD26 level in Asian women with high-grade serous ovarian carcinoma

Aim: The aim of this study was to reveal the diagnostic and prognostic significance of serum CD26 level in high-grade serous ovarian carcinoma women in China. Methods: There were 229 high-grade serous ovarian carcinoma women and 365 controls. Baseline serum CD26 level was measured using ELISA. A 36-month post-operation follow-up was performed. Results: Baseline serum CD26 level ≤601.5 pg/ml was associated with the increased risk of ovarian carcinoma (OR: 1.67; 95% CI: 1.20-2.32). Baseline serum level of CD26 ≤589.7 pg/ml was related to the elevated risk of cancer death (HR: 1.33; 95% CI: 1.04-1.69). Conclusion: Baseline serum CD26 level might be an independent diagnostic and prognostic marker for high-grade serous ovarian carcinoma.

Dipeptidyl peptidase 4 inhibitors as novel agents in improving survival in diabetic patients with colorectal cancer and lung cancer: A Surveillance Epidemiology and Endpoint Research Medicare study

Background

Dipeptidyl peptidase 4 (DPP4) is a cell surface protein that can act as a tumor suppressor or activator, depending upon the level of expression and interaction with the microenvironment and chemokines. DPP4 inhibitors are used to treat diabetes.

Methods

We conducted this Surveillance Epidemiology and Endpoint Research‐Medicare database study to evaluate the role of DPP4 inhibitors on the overall survival (OS) of diabetic patients diagnosed with colorectal (CRC) and lung cancers.

Results

Diabetic patients with CRC or lung cancer who were treated with DPP4 inhibitors exhibited a statistically significant survival advantage (hazard ratio [HR] of 0.89; CI: 0.82‐0.97, P = 0.007) that remained significant after controlling for all other confounders. When DPP4 inhibitors were used in combination of metformin which is known to suppress cancer, the survival advantage was even more pronounced (HR of 0.83; CI: 0.77‐0.90, P < 0.0001). Data were then analyzed separately for two cancer types. In the CRC‐only cohort, the use of DPP4 inhibitors alone had a positive trend but did not meet statistically significant threshold (HR of 0.87; CI: 0.75‐1.00, P = 0.055), while the combined use of DPP4 inhibitors and metformin was associated with statistically significant survival advantage (HR of 0.77; CI: 0.67‐0.89, P = 0.003). Similarly, for the lung cancer cohort, use of DPP4 alone was not found to be statistically significant (HR of 0.93; CI: 0.83‐1.03, P = 0.153), whereas lung cancer patients treated with the combination of DPP4 inhibitors and metformin showed statistically significant survival advantage (HR of 0.88; CI: 0.80‐0.97, P = 0.010).

Conclusions

DPP4 inhibition in CRC and lung cancer is associated with improved OS, which possibly may be due to the effect of DPP4 inhibition on immunoregulation of 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.

Effect of sitagliptin, a DPP-4 inhibitor, against DENA-induced liver cancer in rats mediated via NF-κB activation and inflammatory cytokines

The target of the current research was to investigate the anticancer activity of sitagliptin on diethylnitrosamine (DENA)-induced cancer in the liver. Wistar rats were treated with or without sitagliptin before DENA treatment. We detected liver weight, blood glucose, and histopathology of the liver. Serum biochemical markers like serum glutamate pyruvate transaminase (SGPT), serum glutamate oxaloacetate transaminase (SGOT), serum alkaline phosphatase (SALP), gamma-glutamyl transpeptidase (GGTP), total bilirubin (TBR), total protein (TPR), and albumin (ALB) were also evaluated. In addition, lipid profile parameters comprising total cholesterol (TC), triglycerides, and high-density lipoprotein were also measured. Inflammatory mediators like interleukin-6 (IL-6), interleukin-1beta (IL-1β), and tumor necrosis factor-alpha (TNF-α) were determined in liver homogenate. Furthermore, the activity of nuclear factor (NF-κB) was also measured. Our results showed that sitagliptin (10 and 20 mg/kg) in a dose-dependent manner expressively decreased the DENA-induced elevation of SGPT, SGOT, SALP, and GGTP. Whereas sitagliptin (10 and 20 mg/kg) in a dose-dependent mode reduced the level of TBR and increased the TPR and ALB as well as improved the liver histopathology alterations in DENA-exposed rats. Lipid profile was also restored by the sitagliptin (10 and 20 mg/kg) in a DENA-treated rats. The level of IL-1β, IL-6, and TNF-α were suggestively suppressed. Moreover, pretreatment with sitagliptin (10 and 20 mg/kg) prevented the activation of NF-κB. In conclusion, sitagliptin (10 and 20 mg/kg) has a potential protective effect against DENA-induced liver cancer by inhibition of inflammation and NF-κB activation.

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.

Molecular Evidence of Adenosine Deaminase Linking Adenosine A2A Receptor and CD26 Proteins

Adenosine is an endogenous purine nucleoside that acts in all living systems as a homeostatic network regulator through many pathways, which are adenosine receptor (AR)-dependent and -independent. From a metabolic point of view, adenosine deaminase (ADA) is an essential protein in the regulation of the total intracellular and extracellular adenosine in a tissue. In addition to its cytosolic localization, ADA is also expressed as an ecto-enzyme on the surface of different cells. Dipeptidyl peptidase IV (CD26) and some ARs act as binding proteins for extracellular ADA in humans. Since CD26 and ARs interact with ADA at opposite sites, we have investigated if ADA can function as a cell-to-cell communication molecule by bridging the anchoring molecules CD26 and A2AR present on the surfaces of the interacting cells. By combining site-directed mutagenesis of ADA amino acids involved in binding to A2AR and a modification of the bioluminescence resonance energy transfer (BRET) technique that allows detection of interactions between two proteins expressed in different cell populations with low steric hindrance (NanoBRET), we show direct evidence of the specific formation of trimeric complexes CD26-ADA-A2AR involving two cells. By dynamic mass redistribution assays and ligand binding experiments, we also demonstrate that A2AR-NanoLuc fusion proteins are functional. The existence of this ternary complex is in good agreement with the hypothesis that ADA could bridge T-cells (expressing CD26) and dendritic cells (expressing A2AR). This is a new metabolic function for ecto-ADA that, being a single chain protein, it has been considered as an example of moonlighting protein, because it performs more than one functional role (as a catalyst, a costimulator, an allosteric modulator and a cell-to-cell connector) without partitioning these functions in different subunits.

Potential disease biomarkers: dipeptidyl peptidase 4 and fibroblast activation protein

The importance of the dipeptidyl peptidase 4 (DPP4) gene family in regulating critical biochemical pathways continues to emerge. The two most well-studied members of the family, DPP4 and fibroblast activation protein (FAP), have been investigated both as therapeutic targets for disease and as diagnostic biomarkers. The interest in DPP4 and FAP as potential disease biomarkers has been driven primarily by observations of altered expression profiles in inflammatory diseases and cancer. Furthermore, the stability and persistence of soluble DPP4 and FAP in the serum make them attractive candidate serology markers. This review summarises investigations into DPP4 and FAP as biomarkers of autoimmune disease, gut inflammation, psychosomatic disorders and malignancy and discusses their potential likelihood as clinically useful tools.

Expression and activity of angiotensin-regulating enzymes is associated with prognostic outcome in clear cell renal cell carcinoma patients

The discovery of the intrarenal renin-angiotensin system (iRAS), which regulates angiogenesis, cell differentiation and proliferation, has opened new perspectives in the knowledge of kidney carcinogenesis. In this study we analyzed the immunohistochemical expression and fluorimetric activity of four key peptidases of iRAS in tumor tissue (n = 144) and serum samples (n = 128) from patients with renal neoplasms. Neutral endopeptidase (NEP/CD10), Angiotensin-converting enzyme-2 (ACE2), and aminopeptidase A (APA) were expressed in tumor cells whilst Angiotensin-converting enzyme (ACE) was expressed in the endothelial cells of intratumor blood vessels. The expression of ACE, ACE2 and NEP/CD10 was highest in clear cell renal cell carcinoma (CCRCC) and papillary renal cell carcinoma (PRCC). The expression of these enzymes correlated with CCRCC aggressiveness. In addition, NEP/CD10 correlated with 15-year overall survival. On the other hand, APA expression was decreased in CCRCC with higher grade and stage. The loss of expression of APA independently correlated with a worse 15-year overall survival. Serum activity of ACE2, NEP/CD10 and APA was significantly higher in renal tumor patients than in healthy subjects. Serum ACE activity was lower in high grade and metastatic CCRCC patients, and NEP/CD10 activity was negatively correlated with UISS (UCLA Integrated Staging System) and SSIGN (Mayo Clinic stage, size, grade and necrosis model) scores and with overall survival of CCRCC patients. These results suggest a metabolic imbalance of iRAS in renal tumors. This finding should be taken into account in the search of new diagnostic, prognostic and therapeutic tools for this disease.

Regulation and roles of CD26/DPPIV in hematopoiesis and diseases

Dipeptidyl peptidase IV (DPPIV),¹ on the surface of certain cells, where it is also referred to as CD26, is involved in a vast majority of biological and pathological processes. CD26/DPPIV function contributes to cancer and tumor metastasis as well as inhibition of its expression which alters the expression of immune response-related genes. CD26/DPPIV is a widely distributed multifunctional integral membrane and secreted protein that is defined as early predictive biomarker in HIV, cancer and autoimmunity diseases like diabetes and multiple sclerosis. CD26/DPPIV-chemokine interaction may have a functional role in T-cells and overall immune function. It is expressed at low density on resting T cells, but is upregulated with T cell activation. In this review, we summarize valuable information about detailed biological aspects and pharmacokinetic characteristics of CD26/DPPIV and its clinical efficacy, focusing particularly on the role of CD26/DPPIV in immunological and non-immunological diseases. We also describe our recent work about umbilical cord blood (UCB)² hematopoietic stem cell transplantation strategies in which identified CD26+ cells can be differentiated to immune cells under certain culture condition.

Co-Culture of Tumor Spheroids and Fibroblasts in a Collagen Matrix-Incorporated Microfluidic Chip Mimics Reciprocal Activation in Solid Tumor Microenvironment

Multicellular 3D culture and interaction with stromal components are considered essential elements in establishing a ‘more clinically relevant’ tumor model. Matrix-embedded 3D cultures using a microfluidic chip platform can recapitulate the microscale interaction within tumor microenvironments. As a major component of tumor microenvironment, cancer-associated fibroblasts (CAFs) play a role in cancer progression and drug resistance. Here, we present a microfluidic chip-based tumor tissue culture model that integrates 3D tumor spheroids (TSs) with CAF in proximity within a hydrogel scaffold. HT-29 human colorectal carcinoma cells grew into 3D TSs and the growth was stimulated when co-cultured with fibroblasts as shown by 1.5-folds increase of % changes in diameter over 5 days. TS cultured for 6 days showed a reduced expression of Ki-67 along with increased expression of fibronectin when co-cultured with fibroblasts compared to mono-cultured TSs. Fibroblasts were activated under co-culture conditions, as demonstrated by increases in α-SMA expression and migratory activity. When exposed to paclitaxel, a survival advantage was observed in TSs co-cultured with activated fibroblasts. Overall, we demonstrated the reciprocal interaction between TSs and fibroblasts in our 7-channel microfluidic chip. The co-culture of 3D TS-CAF in a collagen matrix-incorporated microfluidic chip may be useful to study the tumor microenvironment and for evaluation of drug screening and evaluation.

Complement Component 1, s Subcomponent Overexpression is an Independent Poor Prognostic Indicator in Patients with Urothelial Carcinomas of the Upper Urinary Tract and Urinary Bladder

PURPOSE

Urothelial carcinoma of the urinary bladder and upper tract is prevalent. By subjecting a documented transcriptome data set of urothelial carcinoma of bladder (GSE31684) to data mining and focusing on genes linked to peptidase activity (GO:0008233), we recognized C1S as the most significantly upregulated gene related to an advanced tumor status and metastasis. We subsequently analyzed the association of both C1S mRNA and its encoded protein expression with the clinical and pathological significance.

MATERIALS AND METHODS

We used real-time reverse transcription polymerase chain reaction to detect C1S transcription levels in 20 cases each of urothelial carcinoma of bladder and upper tract. An immunohistochemical stain was conducted to determine C1s protein expression levels in patients with urothelial carcinoma of upper tract (n = 340) and urinary bladder (n = 295). Furthermore, we examined the correlation of C1s expression with clinicopathological characteristics, disease-specific survival, and metastasis-free survival.

RESULTS

C1S transcription levels were significantly high in patients with advanced-stage tumors of both groups (all P < .05). Immunohistochemical analysis revealed that C1s expression levels were significantly associated with adverse clinicopathological parameters in both groups of urothelial carcinoma (all P < .05). C1s overexpression predicted poor disease-specific and metastasis-free survival rates for both urothelial carcinoma groups in the univariate analysis, and it was also an independent prognostic factor in the multivariate analysis (all P < .05).

CONCLUSIONS

C1s may play a pivotal role in urothelial carcinoma progress and can represent a vital prognostic marker and a promising new therapeutic target in urothelial carcinoma.

CD26/dipeptidylpeptidase IV-chemokine interactions: double-edged regulation of inflammation and tumor biology

Review of how chemokine processing by CD26/DPP IV regulates leukocyte trafficking.

Post‐translational modification of chemokines is an essential regulatory mechanism to enhance or dampen the inflammatory response. CD26/dipeptidylpeptidase IV, ubiquitously expressed in tissues and blood, removes NH₂‐terminal dipeptides from proteins with a penultimate Pro or Ala. A large number of human chemokines, including CXCL2, CXCL6, CXCL9, CXCL10, CXCL11, CXCL12, CCL3L1, CCL4, CCL5, CCL11, CCL14, and CCL22, are cleaved by CD26; however, the efficiency is clearly influenced by the amino acids surrounding the cleavage site and although not yet proven, potentially affected by the chemokine concentration and interactions with third molecules. NH₂‐terminal cleavage of chemokines by CD26 has prominent effects on their receptor binding, signaling, and hence, in vitro and in vivo biologic activities. However, rather than having a similar result, the outcome of NH₂‐terminal truncation is highly diverse. Either no difference in activity or drastic alterations in receptor recognition/specificity and hence, chemotactic activity are observed. Analogously, chemokine‐dependent inhibition of HIV infection is enhanced (for CCL3L1 and CCL5) or decreased (for CXCL12) by CD26 cleavage. The occurrence of CD26‐processed chemokine isoforms in plasma underscores the importance of the in vitro‐observed CD26 cleavages. Through modulation of chemokine activity, CD26 regulates leukocyte/tumor cell migration and progenitor cell release from the bone marrow, as shown by use of mice treated with CD26 inhibitors or CD26 knockout mice. As chemokine processing by CD26 has a significant impact on physiologic and pathologic processes, application of CD26 inhibitors to affect chemokine function is currently explored, e.g., as add‐on therapy in viral infection and cancer.