Expression of dipeptidyl aminopeptidase IV activity in thyroid carcinoma

Identification of DPP4/CTNNB1/MET as a Theranostic Signature of Thyroid Cancer and Evaluation of the Therapeutic Potential of Sitagliptin

Simple Summary

In recent years, the incidence of thyroid cancer has been increasing globally, with papillary thyroid cancer (PTCa) being the most prevalent pathological type. Although PTCa has been regarded to be slow growing and has a good prognosis, in some cases, PTCa can be aggressive and progress despite surgery and radioactive iodine treatment. Therefore, searching for new targets and therapies is required. We utilized bioinformatics analyses to identify critical theranostic markers for PTCa. We found that DPP4/CTNNB1/MET is an oncogenic signature that is overexpressed in PTCa and associated with disease progression, distant metastasis, treatment resistance, immuno-evasive phenotypes, and poor clinical outcomes. Interestingly, our in silico molecular docking results revealed that sitagliptin, an antidiabetic drug, has strong affinities and potential for targeting DPP4/CTNNB1/MET signatures, even higher than standard inhibitors of these genes. Collectively, our findings suggest that sitagliptin could be repurposed for treating PTCa.

Abstract

In recent years, the incidence of thyroid cancer has been increasing globally, with papillary thyroid cancer (PTCa) being the most prevalent pathological type, accounting for approximately 80% of all cases. Although PTCa has been regarded to be slow growing and has a good prognosis, in some cases, PTCa can be aggressive and progress despite surgery and radioactive iodine treatment. In addition, most cancer treatment drugs have been shown to be cytotoxic and nonspecific to cancer cells, as they also affect normal cells and consequently cause harm to the body. Therefore, searching for new targets and therapies is required. Herein, we explored a bioinformatics analysis to identify important theranostic markers for THCA. Interestingly, we identified that the DPP4/CTNNB1/MET gene signature was overexpressed in PTCa, which, according to our analysis, is associated with immuno-invasive phenotypes, cancer progression, metastasis, resistance, and unfavorable clinical outcomes of thyroid cancer cohorts. Since most cancer drugs were shown to exhibit cytotoxicity and to be nonspecific, herein, we evaluated the anticancer effects of the antidiabetic drug sitagliptin, which was recently shown to possess anticancer activities, and is well tolerated and effective. Interestingly, our in silico molecular docking results exhibited putative binding affinities of sitagliptin with DPP4/CTNNB1/MET signatures, even higher than standard inhibitors of these genes. This suggests that sitagliptin is a potential THCA therapeutic, worthy of further investigation both in vitro and in vivo and in clinical settings.

CD26/DPP4 as a Therapeutic Target in Nonalcoholic Steatohepatitis Associated Hepatocellular Carcinoma

Simple Summary

CD26/DPP4 has been reported to attenuate anticancer immunity via chemokine cleavage and to promote insulin resistance and inflammation in the liver and/or adipose tissue via dysregulation of macrophage M1/M2 polarization. These results suggest the promotive roles of CD26/DPP4 especially in nonalcoholic steatohepatitis (NASH) associated hepatocellular carcinoma (HCC). In this review, we discuss the biological roles of CD26/DPP4 in the development and progression of NASH associated HCC and the potential of DPP4 inhibitors as therapeutic agents for HCC.

Abstract

Hepatocellular carcinoma (HCC) is generally considered an “immune-cold” cancer since T cells are not observed abundantly in HCC tumor tissue. Combination therapy with immune checkpoint inhibitors and vascular endothelial growth factor (VEGF) inhibitors is currently recognized as a first-line systemic treatment for advanced-stage HCC. Immunologically, immune checkpoint inhibitors influence the recognition of cancer cells by T cells, and VEGF inhibitors influence the infiltration of T cells into tumors. However, no drugs that facilitate the trafficking of T cells toward tumors have been developed. Chemokines are promising agents that activate T cell trafficking. On the other hand, metabolic factors such as obesity and insulin resistance are considered risk factors for HCC development. CD26/dipeptidyl peptidase 4 (DPP4) functions as a serine protease, selectively cleaving polypeptides with a proline or alanine at the penultimate N-terminal position, such as chemokines. Recently, CD26/DPP4 has been reported to attenuate anticancer immunity via chemokine cleavage and to promote insulin resistance and inflammation in the liver and/or adipose tissue via dysregulation of macrophage M1/M2 polarization. In this review, we discuss the promotive roles of CD26/DPP4 in HCC development and progression and the potential of DPP4 inhibitors as therapeutic agents for HCC.

Weighted Correlation Network Analysis of Cancer Stem Cell-Related Prognostic Biomarkers in Esophageal Squamous Cell Carcinoma

Background: The role of cancer stem cells in esophageal squamous cell carcinoma (ESCC) remains unclear. Methods: The mRNA stemness index (mRNAsi) of 179 ESCC patients (GSE53625) was calculated using a machine learning algorithm based on their mRNA expression. Stemness-related genes were identified by weighted correlation network analysis (WGCNA) and LASSO regression, whose associations with mutation status, immune cell infiltrations, and potential compounds were also analyzed. The role of these genes in proliferation and their expressions was assessed in ESCC cell lines and 112 samples from our center. Results: The ESCC samples had significantly higher mRNAsi than the normal tissues. Patients with high mRNAsi exhibited higher worse OS. Seven stemness-related genes were identified by WGCNA and LASSO regression, based on which a risk-predicted score model was constructed. Among them, CST1, CILP, PITX2, F2RL2, and RIOX1 were favorable for OS, which were adverse for DPP4 and ZFHX4 in the GSE53625 dataset. However, RIOX1 was unfavorable for OS in patients from our center. In vitro assays showed that CST1, CILP, PITX2, F2RL2, and RIOX1 were pro-proliferated, which were opposite for DDP4 and ZFHX4. In addition, SMARCA4, NOTCH3, DNAH5, and KALRN were more mutated in the low-score group. The low-score group had significantly more memory B cells, monocytes, activated NK cells, and Tregs and less macrophages M2, resting mast cells, and resting dendritic cells. Conclusions: Seven stemness-related genes are significantly related to the prognosis, gene mutations, and immune cell infiltration of ESCC. Some potential anticancer compounds may be favorable for OS.

Diagnostic significance of apical membranous and cytoplasmic dot-like CD26 expression in encapsulated follicular variant of papillary thyroid carcinoma: a useful marker for capsular invasion

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and invasive encapsulated follicular variant of papillary thyroid carcinoma (EFV-PTC) are indistinguishable preoperatively. CD26 expression in follicular tumor-uncertain malignant potential (FT-UMP) is reported to be clearly higher than in that without capsular invasion. To verify the diagnostic significance of CD26 immunostaining in EFV-PTC, we examined the expression pattern of CD26 in non-invasive EFV-PTC (NIFTP) and invasive EFV-PTC. We performed immunohistochemical analysis using CD26 antibody for 37 NIFTPs and 54 EFV-PTCs (34 minimally invasive EFV-PTCs and 20 widely invasive EFV-PTCs). Most NIFTP samples showed an apical membranous pattern or a cytoplasmic diffuse pattern of expression. Invasive EFV-PTCs more frequently showed a cytoplasmic dot-like pattern, and the labeling indices of tumor cells with cytoplasmic dot-like patterns were significantly higher than those in NIFTPs. The sizes of dots seen in NIFTPs (mean: 1.12 μm) were significantly smaller than in invasive EFV-PTCs (1.33 μm), minimally invasive EFV-PTC (1.27 μm), and widely invasive EFV-PTC (1.38 μm). We, therefore, conclude that cytoplasmic diffuse and/or cytoplasmic dot-like CD26 expression, particularly the larger CD26-positive dots, could be useful markers for capsular invasion in EFV-PTC. CD26 immunostaining, using cell blocks or cytological specimens, may preoperatively distinguish between NIFTP and invasive EFV-PTC.

CD26 as a Promising Biomarker for Predicting Prognosis in Patients with Pancreatic Tumors

Purpose

Pancreatic cancer is associated with a high mortality rate owing to insufficient approaches for early diagnosis and the invasive biological behavior of the cancer. CD26 is a membrane-anchored protein involved in multiple physiological and pathological processes. Here, we investigated correlations between CD26 expression and clinicopathological features in patients with pancreatic tumors.

Methods

We collected 170 tumor tissue specimens and 138 paired paratumoral tissues from patients with pancreatic tumors and evaluated CD26 expression using immunohistochemistry.

Results

CD26 was expressed in 79.4% of pancreatic tumors, which was significantly (P < 0.001) higher than that in paratumoral pancreatic tissues (23.2%). High expression of CD26 was correlated with ABO blood type (P = 0.035), malignancy degree (P = 0.001), CA199 (P = 0.01), and CA242 (P = 0.027). In pancreatic malignancies, CD26 expression was observed in 80.7% (130/161) of cases. Lower CD26 expression was correlated with longer disease-free survival (P = 0.048) and overall survival (P = 0.024) and was an independent predictor of overall survival (hazard ratio [HR]: 1.713; P = 0.042). Similar results were observed in pancreatic ductal adenocarcinoma (PDAC) tissues, and CD26 expression level (HR: 2.117; P = 0.008) was an independent predictor of overall survival in patients with PDAC. CD26 expression was significantly increased in pancreatic tumors and gradually increased with increasing malignancy degree, suggesting that CD26 may be involved in the tumorigenic proliferation of pancreatic tumors.

Conclusion

Therefore, CD26 is a potential marker for early diagnosis and a promising therapeutic target in pancreatic tumors.

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.

Gemigliptin, a novel dipeptidyl peptidase-IV inhibitor, exerts a synergistic cytotoxicity with the histone deacetylase inhibitor PXD101 in thyroid carcinoma cells

PURPOSE

The influence of the dipeptidyl peptidase-IV inhibitor gemigliptin alone or in combination with the histone deacetylase inhibitor PXD101 on survival of thyroid carcinoma cells was investigated.

METHODS

SW1736, TPC-1, 8505C and BCPAP human thyroid carcinoma cells were used. To assess cell survival, cell viability, the percentage of viable cells and dead cells, cytotoxic activity, ATP levels and FACS analysis were measured. To validate the impact of gemigliptin combined with PXD101, the interactions were estimated by obtaining combination index in cells treated with two agents.

RESULTS

In cells treated with gemigliptin or PXD101, cell viability, the percentage of viable cells and ATP levels were reduced, and the percentage of dead cells and cytotoxic activity were elevated. In cells treated with both gemigliptin and PXD101, compared with PXD101 alone, cell death was augmented, and all of the combination index values were lower than 1.0, suggesting the synergism between gemigliptin and PXD101. The percentage of apoptotic cells, and the protein levels of Bcl2 and cleaved poly (ADP-ribose) polymerase were elevated, and the protein levels of xIAP and survivin were reduced. The protein levels of phospho-Akt and phospho-AMPK were elevated, and cell migration was reduced.

CONCLUSIONS

Our results demonstrate that gemigliptin induces cytotoxicity in thyroid carcinoma cells. Moreover, gemigliptin has a synergistic activity with PXD101 in the induction of cell death through involvement of Bcl2 family proteins, xIAP and survivin as well as mediation of Akt and AMPK in thyroid carcinoma cells.

Synergistic cytotoxicity of the dipeptidyl peptidase-IV inhibitor gemigliptin with metformin in thyroid carcinoma cells

PURPOSE

The influence of the dipeptidyl peptidase-IV inhibitor, gemigliptin alone or in combination with metformin on survival, proliferation, and migration of thyroid carcinoma cells was investigated.

METHODS

SW1736 and TPC-1 human thyroid carcinoma cells were used.

RESULTS

Gemigliptin and metformin caused cell death in a dose-dependent manner. In cells treated with both gemigliptin and metformin, compared with metformin alone, all of the combination index values were lower than 1.0, suggesting synergistic cytotoxicity of two agents. Cell viability, the percentage of viable cells, ATP levels, and mitochondrial membrane potential decreased; however, cytotoxic activity, and the protein levels of cleaved PARP, phospho-Akt and phospho-AMP-activated protein kinase (AMPK) increased. Administration of wortmannin, but not compound C, further decreased cell viability, and further increased cytotoxic activity. Moreover, compared with control, cell proliferation and migration as well as the protein levels of p53, p21, vascular cell adhesion molecule-1 (VCAM-1), and phospho-extracellular signal-regulated kinase (ERK) 1/2 decreased. The decrement of matrix metalloproteinase-2 and matrix metalloproteinase-9 protein levels was cell specific.

CONCLUSIONS

Our results demonstrate that gemigliptin induces cytotoxic activity, and has a synergistic activity with metformin in inducing cytotoxicity via regulation of Akt and AMPK in thyroid carcinoma cells. Furthermore, gemigliptin augments the inhibitory effect of metformin on proliferation and migration through involvement of matrix metalloproteinase-2, matrix metalloproteinase-9, p53, p21, VCAM-1, and ERK in thyroid carcinoma cells.

Chemotherapeutic agents attenuate CXCL12-mediated migration of colon cancer cells by selecting for CXCR4-negative cells and increasing peptidase CD26

Background

Recurrence of colorectal cancer (CRC) may arise due to the persistence of drug-resistant and cancer-initiating cells that survive exposure to chemotherapy. Proteins responsible for this recurrence include the chemokine receptor CXCR4, which is known to enable CRC metastasis, as well as the cancer-initiating cell marker and peptidase CD26, which terminates activity of its chemokine CXCL12.

Methods

We evaluated the expression and function of CXCR4 and CD26 in colon cancer cell lines and xenografts following treatment with common chemotherapies using radioligand binding, flow cytometry, immunofluorescence, and enzymatic assays.

Results

5-Fluorouracil, oxaliplatin and SN-38 (the active metabolite of irinotecan), as well as cisplatin, methotrexate and vinblastine, each caused decreases in cell-surface CXCR4 and concomitant increases in CD26 on HT-29, T84, HRT-18, SW480 and SW620 CRC cell lines. Flow cytometry indicated that the decline in CXCR4 was associated with a significant loss of CXCR4+/CD26- cells. Elevations in CD26 were paralleled by increases in both the intrinsic dipeptidyl peptidase activity of CD26 as well as its capacity to bind extracellular adenosine deaminase. Orthotopic HT-29 xenografts treated with standard CRC chemotherapeutics 5-fluorouracil, irinotecan, or oxaliplatin showed dramatic increases in CD26 compared to untreated tumors. Consistent with the loss of CXCR4 and gain in CD26, migratory responses to exogenous CXCL12 were eliminated in cells pretreated with cytotoxic agents, although cells retained basal motility. Analysis of cancer-initiating cell CD44 and CD133 subsets revealed drug-dependent responses of CD26/CD44/CD133 populations, suggesting that the benefits of combining standard chemotherapies 5-fluoruracil and oxaliplatin may be derived from their complementary elimination of cell populations.

Conclusion

Our results indicate that conventional anticancer agents may act to inhibit chemokine-mediated migration through eradication of CXCR4+ cells and attenuation of chemokine gradients through elevation of CD26 activity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1702-2) contains supplementary material, which is available to authorized users.

Upregulated expression and activation of membrane‑associated proteases in esophageal squamous cell carcinoma

To better understand the role of membrane-associated proteolytic systems in the development of esophageal cancer, we studied the expression of two serine proteases, fibroblast activation protein-α (FAP-α) and dipeptidyl peptidase IV (DPPIV) and three metalloproteinases, matrix metalloproteinase (MMP)-2, MMP-9 and MT1-MMP in 24 primary esophageal squamous cell carcinoma (ESCC) tissues and paired non-cancer tissues. Using reverse-transcription PCR, western blotting and zymography, we showed that both serine proteases and all three metalloproteinases were highly altered in ESCC. A positive correlation between the expression of FAP-α and DPPIV and the activity of both gelatinases was found. This may indicate that these proteolytic systems are tightly linked to each other and collectively are involved in the process of ECM degradation that facilitates cancer cell invasion and metastasis.

Interspecies differences in membrane-associated protease activities of thyrocytes and their relevance for thyroid cancer studies

Background

To understand the role of proteases involved in human thyroid cancer progression and tissue invasion, thyrocytes from other species could potentially be used provided their characteristics are similar. It is not known whether dipeptidyl peptidase IV and aminopeptidase N activities, which are overexpressed in human thyroid cancer, are, as in human, also absent in normal thyrocytes of other species, making them suitable models for studies on the regulation of these proteases.

Methods

To assess the role of these proteases, activity was measured in thyroid tissue of human, mouse, rat, porcine, bovine and ovine origin. The lysosomal protease, dipeptidyl peptidase II, was used for comparison.

Results

Murine, rat, ovine, bovine and human thyrocytes all lacked dipeptidyl peptidase IV and aminopeptidase N activity, but porcine thyrocytes were found to possess both. In contrast, lysosomal dipeptidyl peptidase II was strongly expressed in all species. These activity patterns were maintained in cultured cells. Cultured porcine thyrocytes formed follicles with typical morphology upon stimulation with TSH but differed from human thyrocytes in their response to thiamazole.

Conclusions

These species differences in the expression of dipeptidyl peptidase IV and aminopeptidase N, indicate that porcine thyrocytes cannot be considered appropriate for the study of proteases in human cancer development.

Blood presence of circulating oncofetal fibronectin mRNA, by RT-PCR, does not represent a useful specific marker for the management and follow-up of thyroid cancer patients

BACKGROUND

Recent studies strongly suggest the use of oncofetal fibronectin (onfFN) mRNA in diagnostic follow-up and staging due to its very high specificity for thyroid cancers. Since the use of this marker has not been well established yet, particularly in the monitoring of minimal residual disease, we have tried to verify the diagnostic power of onfFN and its usefulness as a prognostic molecular marker. For this reason, we evaluated (by RT-PCR) the presence of onfFN mRNAs, not only in blood samples and thyroid tissues (both normal and neoplastic), but also in different biological fluids (such as K3-EDTA blood samples, saliva and urine) belonging to healthy individuals.

METHODS

Molecular investigations, such as RT-PCR protocol, and sequencing of onfFN cDNAs evaluation of the above-mentioned samples were performed.

RESULTS

The onfFN transcript was largely expressed in all benign and malignant thyroid tissues [differentiated thyroid carcinomas (DTCs)] tested as well as in a large number of biological fluids; in particular, 100% urine samples were positive for onfFN transcript as compared to the thyroglobulin (Tg) mRNA (75%), while saliva was always positive for onfFN and never for Tg. These findings indicate that onfFN cannot be considered a marker specific for thyroid cancer presence. Finally, Tg results were positive in a large part of the samples, but not always in concomitance with onfFN.

CONCLUSIONS

We underline how the complexity of onfFN transcripts could affect the RT-PCR procedure. In addition, the presence of onfFN transcripts in several normal and cancer tissues, along with non-thyroid biological fluids or cells, does not allow the use of this marker for cancer monitoring.

Gene expression in poorly differentiated papillary thyroid carcinomas

We used cDNA microarrays to study gene expression in fresh frozen papillary thyroid carcinoma (PTC) specimens. Seven clinically aggressive carcinomas were included, comprising poorly differentiated PTC and tumors with extensive local invasion or synchronous distant metastases. Ten differentiated (classic) papillary thyroid carcinomas (PTC) and non-neoplastic thyroid tissues were also investigated. TaqMan quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridization, and immunohistochemistry verified the differential gene expression. The B-Raf gene was mutated with a T-->A transversion at nucleotide 1799 (V600E) in 8 of 10 differentiated PTC, and in 4 of 7 aggressive carcinomas. Among genes markedly and equally over-expressed in carcinomas of both the aggressive and classic PtC groups, compared to normal thyroid tissue, were CBP/p300 transactivator (CItED1), fibronectin, growth/differentiation factor 15, potassium inwardly rectifying channel KCNJ2, glutaminyl peptide cyclotransferase, WNT7A, and dipeptidyl peptidase IV. A marked upregulation in carcinomas of P-cadherin mRNA and protein concomitant with E-cadherin downregulation, indicates a possible P-E cadherin "switch" in PTC. The growth factor homologue Nel-like 2, dual specificity phosphatase 5, the serine protease kallikrein 10, and also the tight junction genes claudin 1 and claudin 16, were upregulated in classic PTC but not in aggressive tumors, which may be consistent with altered cell polarity in the dedifferentiated PtC. The aggressive, poorly differentiated PtC group was specifically characterized by marked upregulation of several genes related to cell proliferation such as cell division cycle 2 (CDC2), CDC7, kinesin-like 5, ubiquitin conjugating enzyme E2C, and topoisomerase IIalpha, and by upregulation of genes encoding extracellular matrix proteins such as seprase, extracellular matrix protein 1, and several collagens. These aggressive tumors were also characterized by overexpression of the integrin ligand periostin, and in some biopsies also of osteopontin and of the upstream Rac-regulator dedicator of cytokinesis 10 (DOCK10). These data are interpreted to be consistent with altered cell motility, extracellular matrix remodeling and increased cell proliferation, as important processes in PTC tumor progression.

Dipeptidyl peptidase IV expression in thyroid cytology: retrospective histologically confirmed study

Fine needle aspiration cytology (FNAC) of the thyroid gland is a well-established method. However, it has inherent limitations, especially in the diagnosis of follicular and oncocytic tumours and in distinguishing between nuclear atypia in colloid goitre with regressive changes and cystic papillary carcinoma. The aim of our study was to evaluate dipeptidyl peptidase IV (DPP IV) as a marker of malignancy in FNAC. We tested 254 thyroid specimens (intraoperative imprint smears) for DPP IV. The sensitivity was 71%, the specificity was 96%, and the diagnostic accuracy was 93%, respectively, with a threshold of 50% of positive cells. To the best of our knowledge it is the largest histologically confirmed study reported in the literature. We suggest the assessment of DPP IV as an adjunct diagnostic marker of malignancy in thyroid specimens suspicious of papillary carcinoma. However, the value of the marker in follicular lesions is very limited.

Diagnostic utility of galectin-3 and CD26/DPPIV as preoperative diagnostic markers for thyroid nodules

The aim of this study was to search for diagnostic markers that could correctly identify thyroid nodular lesions requiring urgent surgical treatment. We investigated whether galectin-3 and dipeptidyl peptidase IV (CD26/DPPIV) could be potential markers for improving the diagnostic accuracy of conventional cytology. Seventy-nine patients with histologically proven thyroid diseases were analyzed. The immunocytochemical staining results showed galectin-3 expression in neoplastic cells of all 37 papillary carcinomas, five of six follicular carcinomas, all three anaplastic carcinomas, one of three medullary carcinomas, and two of 14 follicular adenomas. All 16 adenomatous goiters were negative for galectin-3 immunostaining. On the other hand, all 37 papillary carcinomas, all six follicular carcinomas, and one of three anaplastic carcinomas revealed CD26/DPPIV expression, whereas all three medullary carcinomas were negative. Among benign thyroid lesions, four of 14 follicular adenomas and two of 16 adenomatous goiters exhibited varying degrees of immunoreactivity for CD26/DPPIV. RT-PCR analysis demonstrated overexpression of galectin-3 and CD26/DPPIV mRNAs in all six papillary and all three follicular carcinomas analyzed, whereas the mRNA expressions of these molecules were barely or not detectable in benign thyroid lesions and normal thyroid tissues, except for one case of follicular adenoma. In conclusion, we demonstrate that galectin-3 and CD26/DPPIV were consistently coexpressed at protein and mRNA levels in differentiated thyroid carcinomas. We propose that combined immunostaining for galectin-3 and CD26/DPPIV in the preoperative evaluation of thyroid nodules may play a role in accurate cytodiagnosis.

Molecular diagnostic tests in the diagnosis and management of thyroid carcinoma

The application of molecular analysis of gene expression to clinical tissue samples represents one of the most exciting new areas in "translational" thyroid cancer research. Current data suggest that molecular diagnostic assays may improve the sensitivity and accuracy of fine needle aspiration of thyroid nodules, fine needle aspiration of metastases, and detection of recurrent disease in peripheral blood samples. It is likely that at least some of these tests will become useful adjuncts in the diagnostic armamentarium of clinical endocrinologists in the future.

Dipeptidyl peptidase IV (DPP IV/CD26) staining predicts distant metastasis of 'benign' thyroid tumor

Because follicular thyroid carcinoma is extremely difficult to diagnose, several cases were encountered which have been rediagnosed as carcinoma due to distant metastasis. In the search for a method of correctly diagnosing 'benign' thyroid tumor, dipeptidyl peptidase (DPP) IV immunostaining was applied to 10 cases whose diagnoses had been corrected to follicular thyroid carcinoma because of distant metastases. The positive rate of immunostaining using paraffin sections in the rediagnosed follicular thyroid carcinoma group (7/10) was much higher than that of the control group (1/29), which consisted of 15 cases of follicular thyroid adenoma and 14 cases of nodular hyperplasia. These results suggested that pre- or postoperative DPP IV staining is useful for predicting distant metastasis of 'benign' thyroid tumor.

Regulation of the expression of aminopeptidase A, aminopeptidase N/CD13 and dipeptidylpeptidase IV/CD26 in renal carcinoma cells and renal tubular epithelial cells by cytokines and cAMP-increasing mediators

Aminopeptidase (AP) A is a transmembrane type II molecule widely distributed in mammalian tissues. Since APA expression may be absent in renal cell carcinoma (RCC), it is possible that there is an altered regulation or other defect of APA upon malignant transformation of proximal tubular cells. However, investigations into the regulation of APA on tumour cells are rare. We report, for the first time, that both transforming growth factor-beta 1 (TGF-beta1) and tumour necrosis factor-alpha (TNF-alpha) down-regulate APA mRNA as well as protein expression in renal tubular epithelial cells and RCC cells in culture. In addition to this, both cytokines decrease dipeptidylpeptidase (DP) IV/CD26 mRNA, but not APN/CD13 mRNA expression. Otherwise, IL-4 and IL-13 increase CD13 as well as CD26 expression, but do not alter APA expression. Interferon-alpha (IFN-alpha), IFN-beta and IFN-gamma increase mRNA expression of all the three membrane ectopeptidases, whereas IL-1, IL-6, IL-7, IL-12 and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been found to be without any significant effect. Treatment of cultured cells with cAMP-increasing agents, such as 8-bromo-cAMP or A23187, results in an increase in APA and DPIV/CD26, but no change in APN/CD13 mRNA expression or even a decrease in it. Furthermore, AP inhibitors can influence APA mRNA expression, since bestatin causes an increase in APA expression in a time- and dose-dependent manner, whereas bestatin does not change CD13 or CD26 expression. No difference could be found with respect to the modulation by different mediators between RCC cells and renal epithelial cells, though permanent tumour cell lines such as Caki-1 and Caki-2 may have lost some of the normally expressed peptidases.

CD26 (Dipeptidyl Aminopeptidase IV) Expression in Normal and Diseased Human Thyroid Glands

The objective of the present study was to investigate CD26 (dipeptidyl aminopeptidase IV) expression in normal and diseased thyroids and its relation to differentiation and cell proliferation. CD 26 was also evaluated as a possible marker of malignancy in thyroid neoplasias. A total of 38 normal thyroids and 117 diseased thyroids (neoplastic and non-neoplastic) were evaluated. CD26 and thyroglobulin (Tg) expression was determined by analyzing at least 200 cells/specimen. A minimum of 500 cells/specimen were counted to calculate the MIB-1-positive cell rate expressed as a percentage of total nucleated epithelial cells. CD26 expression was absent in all thyroids from fetuses and children. Among the adults, 7.1 % had CD26 expression only in oncocytic metaplastic areas. In 3 of the 7 elderly subjects, CD26 expression was present in 0.2-90% of epithelial cells. CD26 expression was observed in all diseased thyroids. Since this enzyme is also expressed in benign conditions, it is not useful as a marker of malignancy. There was no relationship between CD26 and Tg expression. The MIB-1-positive cell rate was found to be low for all kinds of thyroid tissues, and when the cell proliferation rate was analyzed according to CD26 expression, a greater cell proliferation rate was found in CD26-positive differentiated (follicular and papillary) carcinomas than in CD26-negative carcinomas. These results demonstrate that expression of this enzyme is related to the proliferative activity of follicular cells.

CD26 (dipeptidyl peptidase IV/DPP IV) as a novel molecular marker for differentiated thyroid carcinoma

In this report we show that CD26 (dipeptidyl peptidase IV/DPP IV) is a novel molecular marker for differentiated thyroid carcinoma. Northern-blot analysis of 22 various thyroid tissues revealed that CD26 is a more specific marker of differentiated thyroid carcinoma than 3 proto-oncogenes previously reported to increase mRNA expression in thyroid carcinomas: c-met, c-erbB-2 and EGF-R. A comparative study of 3 CD26 assays, Northern blotting, immunohistochemical staining and activity staining clearly showed that CD26 enzyme activity staining is the most specific assay for differentiated thyroid carcinoma, yet the easiest to perform. Activity staining of 216 thyroid tissues detected CD26 in all 52 papillary carcinomas and all 5 follicular carcinomas, while all 58 cases of Graves' disease were CD26-negative. Among benign neoplasms, 54 of 55 adenomatous goiters and 29 of 33 follicular adenomas were CD26 negative. Staining intensity of the enzyme activity was relative to the degree of CD26 mRNA expression. Southern-blot study showed no gene amplification or major translocation of the CD26 gene in 7 papillary carcinomas examined. Based on this study, ectopic expression of CD26 in differentiated thyroid carcinomas is thought to be mainly caused by increased CD26 mRNA expression. In conclusion, CD26 activity staining is a simple, specific assay which should be added to the usual pathological examinations in order to distinguish differentiated thyroid carcinomas from benign thyroid diseases.

Stimulation of the expression and the enzyme activity of aminopeptidase N/CD13 and dipeptidylpeptidase IV/CD26 on human renal cell carcinoma cells and renal tubular epithelial cells by T cell-derived cytokines, such as IL-4 and IL-13

Aminopeptidase N (APN) and dipeptidylpeptidase IV (DPIV) are transmembrane type II molecules widely distributed in mammalian tissues. In recent years, the interest in cell surface peptidases has increased considerably because, among other things, several reports indicate roles of ectopeptidases in tumour cell metastasis. Investigations into the regulation of APN and DPIV on tumour cells are rare. We report, for the first time, that IL-4 and IL-13 can up-regulate protein expression as well as enzymatic activity of both the peptidases on renal carcinoma cells and renal tubular epithelial cells in culture. The analysis of mRNA by competitive polymerase chain reaction (PCR) confirmed our results with respect to the APN increase at the level of gene expression. IL-1 beta and tumour necrosis factor-alpha (TNF-alpha) augmented the IL-4-induced effect with respect to APN but not to DPIV. A 5-day incubation with interferon-gamma (IFN-gamma) increased protein expression, especially of APN and, to a lesser extent, also of DPIV, whereas no significant increase in enzymatic activity could be observed. Small concentrations of transforming growth factor-beta 1 (TGF-beta 1) inhibit the expression and enzyme activity of DPIV. IL-6, IL-7, IL-10 and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been found to be without any effect on APN and DPIV. For a prospective therapeutic regimen with T cell-derived cytokines it has to be considered that--besides their effect on tumour cell growth--cytokines might affect surface ectopeptidases involved in tumour cell adhesion processes. The inhibition of APN and DPIV could be a new approach to suppression of cancer spread.

Expression of dipeptidyl aminopeptidase IV activity in human lung carcinoma

Dipeptidyl aminopeptidase IV (DAP IV) staining was examined in various histological types of lung carcinomas to evaluate this enzyme activity. A total of 45 lung carcinomas were examined for their enzyme activity. Almost all (93.1%) cases of adenocarcinoma were positive for DAP IV activity, whereas all cases of squamous cell carcinoma, small cell carcinoma, large cell carcinoma and carcinoid were negative. DAP IV activity of microsomes in lung carcinomas was significantly higher in papillary adenocarcinomas than in squamous cell carcinomas. These data suggest that DAP IV may be a good marker to distinguish adenocarcinoma from other histological types of lung carcinoma.

Diagnostic usefulness of dipeptidyl aminopeptidase IV monoclonal antibody in paraffin-embedded thyroid follicular tumours

Monoclonal antibodies to dipeptidyl aminopeptidase IV (DAP IV, EC 3.4.14.5) were raised and selectively applied to paraffin-embedded sections of thyroid carcinoma. Five monoclonal antibodies were found to stain paraffin sections of thyroid carcinomas. Using one of these antibodies (44-4), we studied retrospectively aberrant expression of DAP IV in thyroid carcinoma to determine whether immunohistochemical staining with DAP IV antibody is useful in pathological diagnosis. In almost all cases of thyroid follicular and papillary carcinoma, tumour cells were positive (99.0 per cent) with DAP IV, whereas the cases of follicular adenoma showed a low incidence (27.1 per cent) of positive staining. Follicular adenoma with incomplete capsular invasion had a higher positive incidence (50 per cent) than follicular adenoma without incomplete capsular invasion (9.6 per cent). In positive staining cases previously diagnosed as benign tumours, 11 benign cases reacting positively with DAP IV were rediagnosed as carcinoma after re-examination of more thyroid paraffin block sections or serial sections. These findings suggest that DAP IV monoclonal antibody is very useful in distinguishing thyroid follicular carcinoma from follicular adenoma.