Comprehensive analysis of the role of ubiquitin-specific peptidases in colorectal cancer:A systematic review

BACKGROUND Colorectal cancer(CRC)is the third most frequent and the second most fatal cancer.The search for more effective drugs to treat this disease is ongoing.A better understanding of the mechanisms of CRC development and progression may reveal new therapeutic strategies.Ubiquitin-specific peptidases(USPs),the largest group of the deubiquitinase protein family,have long been implicated in various cancers.There have been numerous studies on the role of USPs in CRC;however,a comprehensive view of this role is lacking.AIM To provide a systematic review of the studies investigating the roles and functions of USPs in CRC.METHODS We systematically queried the MEDLINE(via PubMed),Scopus,and Web of Science databases.RESULTS Our study highlights the pivotal role of various USPs in several processes implicated in CRC:Regulation of the cell cycle,apoptosis,cancer stemness,epithelial–mesenchymal transition,metastasis,DNA repair,and drug resistance.The findings of this study suggest that USPs have great potential as drug targets and noninvasive biomarkers in CRC.The dysregulation of USPs in CRC contributes to drug resistance through multiple mechanisms.CONCLUSION Targeting specific USPs involved in drug resistance pathways could provide a novel therapeutic strategy for overcoming resistance to current treatment regimens in CRC.

Comparative Evaluation of Peptidases Produced by Penicillium corylophilum and Penicillium waksmanii in Solid State Fermentation Using Agro-industrial Residues

In this present work, the best conditions for production of peptidases under solid state fermentation by the fungi Penicillium corylophilum and Penicillium waksmanii, partial purification using Sephadex G-75 gel filtration column, as well as the biochemical characterization of the partial purified enzymes were investigated. P. corylophilum showed the best production in medium containing wheat bran, agro-industrial residue, without additives （egg albumin or casein）, in which peptidase activity reached 520 U mL^-1 and the enzyme displayed the optimum activity between pH range from 7 to 8 and 60 ℃. It also showed high stability in wide pH range and temperature until 45 ℃ for 60 min of incubation. On the other hand, P. waksmanii, the best production was noted in a medium containing wheat bran （95%） and casein （5%）, reaching 545 U mL^-1, with proteolytic optimum activity at pH 7.5 and 55 ℃. The enzyme was mainly stable in pH range from 8 to 9 and at temperatures until 45 ℃ for 60 rain of incubation. The peptidases secreted by both fungi were inhibited in the presence of phenylmethane sulfonyl fluoride, showing that they belong to the subclass of serine peptidases.

SERPINH1 promoted the proliferation and metastasis of colorectal cancer by activating PI3K/Akt/mTOR signaling pathway

BACKGROUND Serpin peptidase inhibitor clade H member 1(SERPINH1)was initially recognized as an oncogene implicated in various human malignancies.Nevertheless,the clinical relevance and functional implications of SERPINH1 in colorectal cancer(CRC)remain largely elusive.AIM To investigate the effects of SERPINH1 on CRC cells and its specific mechanism.METHODS Quantitative real-time polymerase chain reaction,western blotting analysis,The Cancer Genome Atlas data mining and immunohistochemistry were employed to examine SERPINH1 expression in CRC cell lines and tissues.A series of in-vitro assays were performed to demonstrate the function of SERPINH1 and its possible mechanisms in CRC.RESULTS SERPINH1 demonstrated elevated expression levels in both CRC cells and tissues,manifested at both mRNA and protein tiers.Elevated SERPINH1 levels correlated closely with advanced T stage,lymph node involvement,and distant metastasis,exhibiting a significant association with poorer overall survival among CRC patients.Subsequent investigations unveiled that SERPINH1 overexpression notably bolstered CRC cell proliferation,invasion,and migration in vitro,while conversely,SERPINH1 knockdown elicited the opposite effects.Gene set enrichment analysis underscored a correlation between SERPINH1 upregulation and genes associated with cell cycle regulation.Our findings underscored the capacity of heightened SERPINH1 levels to expedite G1/S phase cell cycle progression via phosphatidylinositol 3-kinase/AKT/mechanistic target of rapamycin pathway activation,thereby facilitating CRC cell invasion and migration.CONCLUSION These findings imply a crucial involvement of SERPINH1 in the advancement and escalation of CRC,potentially positioning it as a novel candidate for prognostic assessment and therapeutic intervention in CRC management.

Kallikrein-related peptidases 6 and 10 are elevated in cerebrospinal fluid of patients with Alzheimer’s disease and associated with CSF-TAU and FDG-PET

Background:Alterations in the expression of human kallikrein-related peptidases(KLKs)have been described in patients with Alzheimer’s disease(AD).We elucidated the suitability of KLK6,KLK8 and KLK10 to distinguish AD from NC and explored associations with established AD biomarkers.Methods:KLK levels in cerebrospinal fluid(CSF),as determined by ELISA,were compared between 32 AD patients stratified to A/T/(N)system with evidence for amyloid pathology and of 23 normal controls with normal AD biomarkers.Associations between KLK levels and clinical severity,CSF and positron emission tomography(PET)based AD biomarkers were tested for.Results:Levels of KLK6 and KLK10 were significantly increased in AD.KLK6 differed significantly between AD A+/T+/N+and AD A+/T−/N+or NC with an AUC of 0.922.CSF pTau and tTau levels were significantly associated with KLK6 in AD.Conclusions:KLK6 deserves further investigations as a potential biomarker of Tau pathology in AD.

Accurate, automatic annotation of peptidases with hotpep-protease

Peptidases are essential for intracellular protein processing,signaling and homeostasis,physiological processes and for digestion of food.Moreover,peptidases are important biotechnological enzymes used in processes such as industrial food processing,leather manufacturing and the washing industry.Identification of peptidases is a crucial step in their characterization but peptidase annotation is not a trivial task due to their large sequence diversity.In the present study short,conserved sequence profiles were generated for all peptidase families with more than four members in the comprehensive Merops peptidase database.The sequence profiles were combined with the Homology to Peptide Pattern(Hotpep)method for automatic annotation of peptidases.This method is a standalone software that annotates protease sequences to Merops family and subgroup and is suitable for large-scale sequence analysis.Compared to the Mammalian Degradome Database Hotpep-protease had an accuracy of 92%and a sensitivity of 96%for annotation of the human degradome.Annotation by commonly used methods(Blast and conserved domains)had an accuracy of 69%and a sensitivity of 78%.For fungal genomes,there were large differences between annotation with Hotpep-protease,Blast-and Hidden Markov Model-based annotation and the Merops annotation,which confirms the difficulty of large-scale peptidase annotation.Manual annotation indicated that Hotpep-protease had a positive prediction rate of 0.90 compared to a positive prediction rate of 0.67 for Blast search.Hence,Hotpep-protease is highly accurate method for fast and accurate annotation of peptidases.

Exendin-4 and linagliptin attenuate neuroinflammation in a mouse model of Parkinson's disease

Use of glucagon-like peptide-1 receptor agonist or dipeptidyl peptidase 4 inhibitor has been shown to lower the incidence of Parkinson's disease in patients with diabetes mellitus.Therefore,using these two treatments may help treat Parkinson's disease.To further investigate the mechanisms of action of these two compounds,we established a model of Parkinson's disease by treating mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and then subcutaneously injected them with the glucagon-like peptide-1 receptor agonist exendin-4 or the dipeptidyl peptidase 4 inhibitor linagliptin.We found that both exendin-4 and linagliptin reversed motor dysfunction,glial activation,and dopaminergic neuronal death in this model.In addition,both exendin-4 and linagliptin induced microglial polarization to the anti-inflammatory M2 phenotype and reduced pro-inflammatory cytokine secretion.Moreover,in vitro experiments showed that treatment with exendin-4 and linagliptin inhibited activation of the nucleotide-binding oligomerization domain-and leucine-rich-repeat-and pyrin-domaincontaining 3/caspase-1/interleukin-1βpathway and subsequent pyroptosis by decreasing the production of reactive oxygen species.These findings suggest that exendin-4 and linagliptin exert neuroprotective effects by attenuating neuroinflammation through regulation of microglial polarization and the nucleotidebinding oligomerization domain-and leucine-rich-repeat-and pyrin-domain-containing 3/caspase-1/interleukin-1βpathway in a mouse model of Parkinson's disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.Therefore,these two drugs may serve as novel anti-inflammatory treatments for Parkinson's disease.

Melatonin inhibits ESCC tumor growth by mitigating the HDAC7/β-catenin/c-Myc positive feedback loop and suppressing the USP10-maintained HDAC7 protein stability

Background:Melatonin,a natural hormone secreted by the pineal gland,has been reported to exhibit antitumor properties through diverse mechanisms of action.However,the oncostatic function of melatonin on esophageal squamous cell carcinoma(ESCC) remains elusive.This study was conducted to investigate the potential effect and underlying molecular mechanism of melatonin as single anticancer agent against ESCC cells.Methods:ESCC cell lines treated with or without melatonin were used in this study.In vitro colony formation and 5-Ethynyl-2’-deoxyuridine(EdU) incorporation assays,and nude mice tumor xenograft model were used to confirm the proliferative capacities of ESCC cells.RNA-seq,qPCR,Western blotting,recombinant lentivirus-mediated target gene overexpression or knockdown,plasmids transfection and co-IP were applied to investigate the underlying molecular mechanism by which melatonin inhibited ESCC cell growth.IHC staining on ESCC tissue microarray and further survival analyses were performed to explore the relationship between target genes’ expression and prognosis of ESCC.Results:Melatonin treatment dose-dependently inhibited the proliferative ability and the expression of histone deacetylase 7(HDAC7),c-Myc and ubiquitin-specific peptidase 10(USP10) in ESCC cells(P<0.05).The expressions of HDAC7,c-Myc and USP10 in tumors were significantly higher than the paired normal tissues from 148 ESCC patients(P<0.001).Then,the Kaplan-Meier survival analysis suggested that ESCC patients with high HDAC7,c-Myc or USP10levels predicted worse overall survival(log-rank P<0.001).Co-IP and Western blotting further revealed that HDAC7physically deacetylated and activated β-catenin thus promoting downstream target c-Myc gene transcription.Notably,our mechanistic study validated that HDAC7/β-catenin/c-Myc could form the positive feedback loop to enhance ESCC cell growth,and USP10 could deubiquitinate and stabilize HDAC7 protein in the ESCC cells.Additionally,we verified that inhibition of the HDAC7/β-catenin/c-Myc axis and USP10/HDAC7 pathway mediated the anti-proliferative action of melatonin on ESCC cells.Conclusions:Our findings elucidate that melatonin mitigates the HDAC7/β-catenin/c-Myc positive feedback loop and inhibits the USP10-maintained HDAC7 protein stability thus suppressing ESCC cell growth,and provides the reference for identifying biomarkers and therapeutic targets for ESCC.

Immp2l Mutation Induces Mitochondrial Membrane Depolarization and Complex Ⅲ Activity Suppression after Middle Cerebral Artery Occlusion in Mice

Objective We previously reported that mutations in inner mitochondrial membrane peptidase 2-like(Immp2l)increase infarct volume,enhance superoxide production,and suppress mitochondrial respiration after transient cerebral focal ischemia and reperfusion injury.The present study investigated the impact of heterozygous Immp2l mutation on mitochondria function after ischemia and reperfusion injury in mice.Methods Mice were subjected to middle cerebral artery occlusion for 1 h followed by 0,1,5,and 24 h of reperfusion.The effects of Immp2l^(+/−)on mitochondrial membrane potential,mitochondrial respiratory complex III activity,caspase-3,and apoptosis-inducing factor(AIF)translocation were examined.Results Immp2l^(+/−)increased ischemic brain damage and the number of TUNEL-positive cells compared with wild-type mice.Immp2l^(+/−)led to mitochondrial damage,mitochondrial membrane potential depolarization,mitochondrial respiratory complex III activity suppression,caspase-3 activation,and AIF nuclear translocation.Conclusion The adverse impact of Immp2l^(+/−)on the brain after ischemia and reperfusion might be related to mitochondrial damage that involves depolarization of the mitochondrial membrane potential,inhibition of the mitochondrial respiratory complex III,and activation of mitochondria-mediated cell death pathways.These results suggest that patients with stroke carrying Immp2l^(+/−)might have worse and more severe infarcts,followed by a worse prognosis than those without Immp2l mutations.

Compound heterozygous mutations in tripeptidyl peptidase 1 cause rare autosomal recessive spinocerebellar ataxia type 7:A case report

BACKGROUND Spinocerebellar ataxia recessive type 7(SCAR7)is a rare clinical manifestation beginning in childhood or adolescence.SCAR7 is caused by tripeptidyl peptidase 1(TPP1)gene mutations,and presents with cerebellar ataxia,pyramidal signs,neurocognitive impairment,deep paresthesia,and cerebellar atrophy.CASE SUMMARY Here,we describe a 25-year-old female patient in China who presented with increasing difficulty walking,falling easily,shaking limbs,instability holding items,slurred speech,coughing when drinking,palpitations,and frequent hunger and overeating.Magnetic resonance imaging showed cerebellar atrophy.Whole exome sequencing detected two compound heterozygous mutations in the TPP1 gene:c.1468G>A p.Glu490Lys and c.1417G>A p.Gly473Arg.Considering the patient’s clinical presentation and genetic test results,we hypothesized that complex heterozygous mutations cause TPP1 enzyme deficiency,which may lead to SCAR7.CONCLUSION We report the first case of SCAR7 from China.We also identify novel compound heterozygous mutations in the TPP1 gene associated with SCAR7,expanding the range of known disease-causing mutations for SCAR7.

加用维格列汀治疗超重或肥胖2型糖尿病患者的疗效及对胰岛细胞功能的影响

目前,2型糖尿病(T2DM)患病率逐年升高,我国18岁及以上成年人T2DM患病率已高达11.6%。T2DM的主要发病机制是胰岛素抵抗和胰岛素分泌不足。胰岛素抵抗在T2DM中患病率超过80%[1]。维格列汀是一类二肽基肽酶Ⅳ(Dipeptidyl peptidaseⅣ,DPP-Ⅳ)抑制剂,能够抑制胰高血糖素释放,促进胰岛素分泌,阻止β细胞凋亡[2,3]。

Cysteine peptidase and its inhibitor activity levels and vitamin E concentration in normal human serum and colorectal carcinomas

AIM: Cysteine peptidase (CP) and its inhibitor (CPI) are a matrix protease that may be associated with colorectal carcinoma invasion and progression, and vitamin E is also a stimulator of the immunological system. Our purpose was to determine the correlation between the expression of cysteine peptidases and their endogenous inhibitors,and the level of vitamin E in sera of patients with colorectal cancer in comparison with healthy individuals.METHODS: The levels of cysteine peptidases and their inhibitors were determined in the sera of patients with primary and metastatic colorectal carcinoma and healthy individuals using fluorogenic substrate, and the level of vitamin E was determined by HPLC.RESULTS: The levels of cysteine peptidases and their inhibitors were significantly higher in the metastatic colorectal cancer patients than that in the healthy controls (P＜0.05).The activity of CP increased 2.2-fold, CPI 2.8-fold and vitamin E decreased 3.4-fold in sera of patients with metastasis in comparison with controls. The level of vitamin E in healthy individuals was higher, whereas the activity of cysteine peptidases and their inhibitors associated with complexes was lower than that in patients with cancer of the digestive tract.CONCLUSION: These results suggest that the serum levels of CP and their inhibitors could be an indicator of the prognosis for patients with metastatic colorectal cancer. Vitamin E can be administered prophylactically to prevent digestive tract neoplasmas.

Development and evaluation of an ELISA method for the measurement of kallikrein-related peptidase 5 (KLK5) in human serum

Kallikrein-related peptidases (KLKs) have been proposed as potential cancer biomarkers. Kallikrein-related peptidase 5 (KLK5) is a secreted trypsin-like protease of the KLKs. Until now, detection of KLK5 in both biological fluids and tissues has been described frequently due to the potential of being a new cancer biomarker. Our objective was to prepare KLK5 antibodies and establish an ELISA method for KLK5 to study the possible clinical application of KLK5 as a biomarker for malignancies. In this study, recombinant KLK5 protein was produced and purified using a prokaryotic expression system, and then used as immunogen to generate antibodies. High titers of specific antibodies were measured in serum of rabbits after the forth booster injection. And the titer of the antiserum reached 1:106. We have also generated monoclonal antibodies using hybridoma technology and the titer reached 1:105. The activity of KLK5 antibodies was characterized by Western blot and immunohistochemistry. To quantitatively examine KLK5 in serum samples, we established double antibody sandwich ELISA method using mouse mAb as capture and rabbit pAb as tracer antibody. We have detected KLK5 levels in ovarian cancer serum to ensure that our sandwich ELISA measurement to have high sensitivity and specificity. The ranges of linearity reached by the standard curves of the newly developed ELISA were 0.45 ng/mL to 125 ng/mL. The detection limit of the method, defined as the concentration of KLK5 can be distinguished, was 0.20 ng/mL. Median serum KLK5 levels were 3.77 ng/mL and 0.86 ng/mL in ovarian cancer patients and normal female, respectively (P ELISA assay for KLK5. Our preliminary findings prompt that KLK5 may be a new potential biomarker for the diagnosis and prognosis in patients with ovarian.

Proteolysis in the Subtropical Woody Tree <i>Anadenanthera colubrina</i>(Angico) Seeds during and after Germination

Proteolysis of seed storage proteins (SSP) during germination provides a steady supply of amino acids to the embryo development into seedling. This process is coordinated by different peptidases that act sequentially and overlaid mode. These enzymes are an ancient group evolved separately in a wide structural and functional diversity and have many applications in medicine, pharmacy and industry. However, the knowledge about seed peptidases during germination was obtained from studies almost restricted to the cultivated species. This restriction implies caution about generalizations made from these studies, as well limits the biological knowledge about plant kingdom and technological use from plant peptidases. In this work, a scan of the proteolytic activity was held in germinating seeds of a leguminous subtropical woody tree. Eleven proteolytic activities were detected in protein extracts from embryonic axis and cotyledons. The presence and intensity of these activities varied over time and between these tissues. There was indication that aspartyl-endopeptidases (phytepsins) and cysteine-carboxypeptidases (plant cathepsins) were involved in A. colubrina SSP hydrolysis. These peptidases differ to that commonly involved in germination of the cultivated leguminous. In addition, one of detected phytepsins showed stability on pH scale, which is important for industrial uses. There was also detected a metallo-carboxypeptidase activity, which has been not described in plants. These peptidases must be isolated to confirm or not these indications. However, these data indicate the biological and technological importance of extending the studies about plant peptidases on a diverse genetic basis.

Isolation and physiological characteristics of a premature senescence mutant in rice(Oryza sativa L.)

A rice pse（t） （premature senescence, tentatively） mutant line, was isolated from 4500 independent T-DNA inserted transgenic lines. The symptoms of premature senescence appeared more severely than those of the control plants （Zhonghua 11, japonica） at the last development stage. To characterize the mutant and provide basic information on the candidate genes by mapping to a physical region of 220-kb, experiments were carried out in two phytotrons under controlled temperature of 24 ℃ and 28 ℃, respectively. The content of chlorophyll, soluble protein and MDA （malondialdehyde）, net photosynthesis, the antioxidant enzyme activities of SOD （superoxide dismuase） （EC 1.15.1.1 ） and POD （peroxidase） （EC 1.11.1.7） and the peptidase activities of leaves were measured from top to bottom according to the leaf positions at the flowering stage. Compared with the control plant, the mutant showed the following characteristics： （1） Higher net photosynthesis rate （Pn） appeared in the 1st and 2nd leaves, contents of chlorophyll and soluble protein were also higher in the 1st leaf; （2） The activities of SOD, POD and peptidase were higher according to the leaf position from top to bottom; （3） The symptom of premature senescence was accelerated in the mutant at 28 ℃ treatment. The MDA content and the SOD and POD activities between the 24 ℃ and 28 ℃ treatment mutants were not significantly different. Content of chlorophyll and soluble protein of leaves mutant decreased rapidly at 28 ℃ treatment. The results show thatpse（t） is sensitive to high temperature. The probable function of PSE（T） is discussed.

Diabetes treatment in patients with renal disease: Is the landscape clear enough?

Diabetes is the most important risk factors for chronic kidney disease(CKD). The risk of CKD attributable to diabetes continues to rise worldwide. Diabetic patients with CKD need complicated treatment for their metabolic disorders as well as for related comorbidities. They have to treat, often intensively, hypertension, dyslipidaemia, bone disease, anaemia, and frequently established cardiovascular disease. The treatment of hypoglycaemia in diabetic persons with CKD must tie their individual goals of glycaemia(usually less tight glycaemic control) and knowledge on the pharmacokinetics and pharmacodynamics of drugs available to a person with kidney disease. The problem is complicated from the fact that in many efficacy studies patients with CKD are excluded so data of safety and efficacy for these patients are missing. This results in fear of use by lack of evidence. Metformin is globally accepted as the first choice in practically all therapeutic algorithms for diabetic subjects. The advantages of metformin are low risk of hypoglycaemia, modest weight loss, effectiveness and low cost. Data of UKPDS indicate that treatment based on metformin results in less total as well cardiovascular mortality. Metformin remains the drug of choice for patients with diabetes and CKD provided that their estimate Glomerular Filtration Rate(eGFR) remains above 30 mL/min per square meter. For diabetic patients with eGFR between 30-60 mL/min per square meter more frequent monitoring of renal function and dose reduction of metformin is needed. The use of sulfonylureas, glinides and insulin carry a higher risk of hypoglycemia in these patients and must be very careful. Lower doses and slower titration of the dose is needed. Is better to avoid sulfonylureas with active hepatic metabolites, which are renally excreted. Very useful drugs for this group of patients emerge dipeptidyl peptidase 4 inhibitors. These drugs do not cause hypoglycemia and most of them(linagliptin is an exception) require dose reduction in various stages of renal disease.

Linagliptin alleviates fatty liver disease in diabetic db/db mice

AIM To study the effects of linagliptin on the structural signs of non-alcoholic fatty liver disease(NAFLD) in db/db mice. METHODS Male diabetic db /db mice(BKS.Cg-Dock7m+/+Leprdb/J) aged 10 wk received the dipeptidyl peptidase 4(DPP4) inhibitor linagliptin(10 mg/kg) or saline as a placebo once per day by gavage for 8 wk. Intact db/db mice served as controls. Structural changes in the liver were analyzed from light and electron microscopic images of sections from intact, placebo-treated and linagliptin-treated animals. We estimated the changes in hepatocytes, sinusoidal cells, liver microvasculature and lymphatic roots. Hepatic staining for lymphatic vessel endothelial hyaluronan receptor-1(LYVE-1) was assessed by immunohistochemistry. RESULTS In 18-wk-old diabetic mice, liver steatosis(predominantly microvesicular and mediovesicular steatosis) was accompanied by dilation of the roots of the lymphatic system, interlobular blood vessels and bile canaliculi. Compared to saline-treated mice, linagliptin-treated mice exhibited a reduction in the mean numeral densities of hepatocytes with lipid droplets(92.4% ± 1.7% vs 64.9% ± 5.8% per field of view, P = 0.0002) and a lower proportion of hepatocytes with a high density of lipid droplets(20.7% ± 3.6% vs 50.4% ± 3.1%, P = 0.0007). We observed heterogeneous hepatocytes and relatively preserved cell structures in the linagliptin group. Dilation of blood and lymphatic vessels, as well as ultrastructural changes in the hepatocyte endoplasmic reticulum and mitochondria, were alleviated by linagliptin treatment. In intact and placebo-treated mice, immunohistochemical staining for LYVE-1 was observed in the endothelial cells of interlobular lymphatic vessels and on the membranes of some endothelial sinusoidal cells. We observed an enlarged LYVE-1 reaction area in linagliptin-treated mice compared to intact and placebo-treated mice. The improvement in the structural parameters of the liver in linagliptin-treated mice was independent to changes in the plasma glucose levels. CONCLUSION The DPP4 inhibitor linagliptin alleviates liver steatosis and structural changes in the hepatic microvasculature and lymphatic roots in a model of NAFLD in diabetic db/db mice.

The role of peptidase neurolysin in neuroprotection and neural repair after stroke

Current experimental stroke research has evolved to focus on detailed understanding of the brain’s self-protective and restorative mechanisms,and harness this knowledge for development of new therapies.In this context,the role of peptidases and neuropeptides is of growing interest.In this focused review,peptidase neurolysin(Nln)and its extracellular peptide substrates are briefly discussed in relation to pathophysiology of ischemic stroke.Upregulation of Nln following stroke is viewed as a compensatory cerebroprotective mechanism in the acute phase of stroke,because the main neuropeptides inactivated by Nln are neuro/cerebrotoxic(bradykinin,substance P,neurotensin,angiotensin II,hemopressin),whereas the peptides generated by Nln are neuro/cerebroprotective(angiotensin-(1–7),Leu-/Met-enkephalins).This notion is confirmed by experimental studies documenting aggravation of stroke outcomes in mice after inhibition of Nln following stroke,and dramatic improvement of stroke outcomes in mice overexpressing Nln in the brain.The role of Nln in the(sub)chronic phase of stroke is less clear and it is likely,that this peptidase does not have a major role in neural repair mechanisms.This is because,the substrates of Nln are less uniform in modulating neurorestorative mechanisms in one direction,some appearing to have neural repair enhancing/stimulating potential,whereas others doing the opposite.Future studies focusing on the role of Nln in pathophysiology of stroke should determine its potential as a cerebroprotective target for stroke therapy,because its unique ability to modulate multiple neuropeptide systems critically involved in brain injury mechanisms is likely advantageous over modulation of one pathogenic pathway for stroke pharmacotherapy.

Potential of soluble CD26 as a serum marker for colorectal cancer detection

Colorectal cancer is characterized by a low survival rate even though the basis for colon cancer development,which involves the evolution of adenomas to carcinoma,is known.Moreover,the mortality rates continue to rise in economically transitioning countries although there is the opportunity to intervene in the natural history of the adenoma–cancer sequence through risk factors,screening,and treatment.Screening in particular accounted for most of the decline in colorectal cancer mortality achieved in the USA during the period 1975-2000.Patients show a better prognosis when the neoplasm is diagnosed early.Among the variety of screening strategies,the methods range from invasive and costly procedures such as colonoscopy to more low-cost and non-invasive tests such as the fecal occult blood test(guaiac and immunochemical).As a non-invasive biological serum marker would be of great benefit because of the performance of the test,several biomarkers,including cytologic assays,DNA and mRNA,and soluble proteins,have been studied.We found that the soluble CD26(sCD26)concentration is diminished in serum of colorectal cancer patients compared to healthy donors,suggesting the potential utility of a sCD26 immunochemical detection test for early diagnosis.sCD26 originates from plasma membrane CD26 lacking its transmembrane and cytoplasmic domains.Some 90%–95%of sCD26 has been associated with serum dipeptidyl peptidase IV(DPPIV)activity.DPP-IV,assigned to the CD26 cluster,is a pleiotropic enzyme expressed mainly on epithelial cells and lymphocytes.Our studies intended to validate this test for population screening to detect colorectal cancer and advanced adenomas are reviewed here.

Dipeptidyl peptidase Ⅳ(DPP Ⅳ):a novel emerging target for thetreatment of type 2 diabetes

The enzyme, dipeptidyl peptidase IV（DPP IV）, is a novel target for the treatment of type 2 diabetes. Dipeptidyl peptidase IV inhibition improves the impaired insulin secretion and decrease postprandial concentrations of glucagon by enhancing the incretin hormone levels lucagon-like peptide-1（GLP-1） and glucose-dependent insulinotropic polypeptide/gastric inhibitory polypeptide（GIP）. Recently, DPP IV inhibitors have attracted more and more attention, several of which have entered pre-clinical and clinical trials, and one has received approval for use as an anti-diabetic agent. Among the DPP IV inhibitors, two leading agents（sitagliptin and vildagliptin） have been shown to be effective in reducing glycosylated hemoglobin（HbAlc） and fasting plasma glucose（FPG） in patients with type 2 diabetes. This review summarizes the evidence supporting DPP IV inhibitors as potential antidiabetic agents.

Anti-diabetic potential of Urena lobata leaf extract through inhibition of dipeptidyl peptidase IV activity

Objective: To evaluate the anti-diabetic potential of leaf extract from Urena lobata(U. lobata) through dipeptidyl peptidase IV(DPP-IV) inhibitory activity.Methods: U. lobata leaf was extracted in hot water and ethanol. The activity of DPPIV inhibitor was tested by in vitro study using gly-pro-p-nitroanilide as substrat of DPPIV and vildagliptin, as standard reference. A product of the reactions between gly-pro-pnitroanilide and DPP-IV, was observed by microplate readers with λ = 405 nm. All data were expressed as mean ± SD and the IC50 value was determined by non linear regression curve fit. Active substances in leaf extract of U. lobata was analyzed by liquid chromatography-mass spectrometry. DPP-IV inhibitory activity of active compounds was evaluated in silico using docking server. Results: The ethanolic extract of U. lobata showed stronger DPP-IV inhibitor activity than water extract with the IC50 values of 1 654.64 and 6 489.88 μg/mL, respectively. Vildagliptin, based on standard reference for DPP-IV inhibitor activity, has IC50 value of 57.44 μg/mL. Based on in silico analysis, mangiferin, stigmasterol and β-sitosterol in U. lobata extract have a strong inhibitory activity on DPP-IV. Conclusions: The results showed that DPP-IV inhibitory activity of U. lobata is related to its active compounds such as mangiferin, stigmasterol and β-sitosterol.