Aminopeptidase A expression in cervical neoplasia and its relationship to neoplastic transformation and progression

Identifying SCC Lesions Capable of Spontaneous Regression by Using Immunohistochemistry: A Systematic Review and Meta-Analysis

INTRODUCTION

Keratoacanthoma (KA) and squamous cell carcinoma (SCC) are two cutaneous conditions with morphological resemblance, which can complicate the diagnosis in some cases. Using immunohistochemistry staining of biomarkers could be beneficial in resolving this obstacle.

OBJECTIVES

We investigated a variety of biomarkers assessed in different studies in order to find the most important and helpful biomarkers for differentiation between SCC and lesions capable of spontaneous regression.

METHODS

MEDLINE via PubMed and Google Scholar database were used to identify relevant literature up to 15 June 2022. The aim of our analyses was to determine the capability of biomarkers to distinguish between SCC and lesions capable of spontaneous regression using calculated individual and pooled odds ratios (OR) and 95% confidence intervals (CI) and I2 tests.

RESULTS

Six potential biomarkers were CD10 with pooled OR= 0.006 (95% CI: 0.001-0.057) and I2=0%; COX-2 with pooled OR=0.089 (95% CI: 0.029-0.269) and I2=17.1%; elastic fibers with pooled OR= 6.69 (95% CI: 2.928-15.281) and I2=0%; IMP-3 with pooled OR=0.145 (95% CI: 0.021-1.001) and I2=44.5%; P53 with pooled OR=0.371 (95% CI: 0.188-0.733) and I2=55.9%; AT1R with OR=0.026 (95% CI: 0.006-0.107).

CONCLUSIONS

We suggest the utilization of the following IHC biomarkers for discrimination between lesions with spontaneous regression such as KA and SCC: CD10, COX-2, and elastic fibers.

Differential Effects of Doxazosin on Renin-Angiotensin-System- Regulating Aminopeptidase Activities in Neuroblastoma and Glioma Tumoral Cells

Background:

It has been described that doxazosin, an antihypertensive drug, also promotes glioblastoma cells death by inhibiting cell proliferation, arresting cell cycle and inducing apoptosis. Doxazosin has also demonstrated several modulator effects on renin-angiotensin system (RAS)- regulating aminopeptidase activities, which are highly involved in tumor growth in experimental glioma. Therefore, it remains to elucidate if the anti-tumoral effects of doxazosin could also be mediated by the proteolytic regulatory components of the RAS.

Objective:

To analyze the effects of doxazosin on cell growth and on RAS-regulating proteolytic regulatory aspartyl aminopeptidase (ASAP), aminopeptidase A (APA), aminopeptidase N (APN), aminopeptidase B (APB) and insulin-regulated aminopeptidase (IRAP) specific activities in the human neuroblastoma NB69 and astroglioma U373-MG tumoral cell lines.

Methods:

Human neuroblastoma NB69 and astroglioma U373-MG cell lines were treated with doxazosin 50-500 μM for 24h or 48h. The effects on cell growth and on RAS-regulating aminopeptidase specific activities were analyzed.

Results:

Doxazosin treatments promote a concentration-dependent inhibition on cell growth in both NB69 and U373-MG cells, being NB69 cells more sensitive to the drug than U373-MG cells. However, its effects on RAS-regulating aminopeptidase specific activities depend on the concentration used, the duration of the treatment and the cell type. These data confirm the existence of a different dynamic progression of RAS cascade in each tumoral cell line as a consequence of the treatment with doxazosin and time of action, which also implies a very dynamic metabolism of the peptides which participate in each step of RAS cascade.

Conclusion:

Our results indicate that doxazosin modifies the proteolytic regulatory enzymes of RAS cascade, modulating the bioactive efficacy of the different angiotensin peptides, and therefore, of their functional roles as initiators/promoters of cell proliferation as autocrine/paracrine mediators.

Role of proteases in the pathophysiology of cardiac disease

Cardiovascular disease is a major cause of death and thus a great deal of effort has been made in salvaging the diseased myocardium. Although various factors have been identified as possible causes of different cardiac diseases such as heart failure and ischemic heart disease, there is a real need to elucidate their role for the better understanding of the cardiac disease pathology and formulation of strategies for developing newer therapeutic interventions. In view of the intimate involvement of different types of proteases in maintaining cellular structure, the role of proteases in various cardiac diseases has become the focus of recent research. Proteases are present in the cytosol as well as are localized in a number of subcellular organelles in the cell. These are known to use extracellular matrix, cytoskeletal, sarcolemmal, sarcoplasmic reticular, mitochondrial and myofibrillar proteins as substrates. Work from different laboratories using a wide variety of techniques has shown that the activation of proteases causes alterations of a number of specific proteins leading to subcellular remodeling and cardiac dysfunction. Inhibition of protease action by different drugs and agents, therefore, has a clinical relevance and is expected to form a part of new treatment paradigm for improving heart function. This review examines the biochemistry and localization of some of the proteases in the cardiac tissue in addition to identification of the sites of action of some protease inhibitors. (Mol Cell Biochem 263: 241-256, 2004).

Structural and theoretical studies on rhodium and iridium complexes with 5-nitrosopyrimidines. Effects on the proteolytic regulatory enzymes of the renin-angiotensin system in human tumoral brain cells

The reactions of [RhCl(CO)(PPh3)2], [RhCl(CO)2]2 and [IrCl(CO)(PPh3)2] with different 5-nitrosopyrimidines afforded sixteen complexes which have been structurally characterized by elemental analysis, IR and NMR ((1)H and (13)C) spectral methods and luminescence spectroscopy. The crystal and molecular structures of [Rh(III)Cl(VIOH-1)2(PPh3)], [Rh(III)Cl(DVIOH-1)2(PPh3)] and [Rh(II)(DVIOH-1)2(PPh3)2] have been established from single crystal x-ray structure analyses. The three complexes are six-coordinated with both violurato ligands into an equatorial N5,O4-bidentate fashion, but with different mutually arrangements. Theoretical studies were driven on the molecular structure of [Rh(III)Cl(VIOH-1)2(PPh3)] to assess the nature of the metal-ligand interaction as well as the foundations of the cis-trans (3L-2L) isomerism. An assortment of density functional (SOGGA11-X, B1LYP, B3LYP, B3LYP-D3 and wB97XD) has been used, all of them leading to a similar description of the target system. Thus, a topological analysis of the electronic density within AIM scheme and the study of the Mulliken charges yield a metal-ligand link of ionic character. Likewise, it has been proved that the cis-trans isomerism is mainly founded on that metal-ligand interaction with the relativistic effects playing a significant role. Although most of the compounds showed low direct toxicity against the human cell lines NB69 (neuroblastoma) and U373-MG (astroglioma), they differently modify in several ways the renin-angiotensin system (RAS)-regulating proteolytic regulatory enzymes aminopeptidase A (APA), aminopeptidase N (APN) and insulin-regulated aminopeptidase (IRAP). Therefore, these complexes could exert antitumor activity against both brain tumor types, acting through the paracrine regulating system mediated by tissue RAS rather than exerting a direct cytotoxic effect on tumor cells.

Multifunctional nanoparticles: cost versus benefit of adding targeting and imaging capabilities

Nanoparticle-based drug delivery systems have been developed to improve the efficacy and reduce the systemic toxicity of a wide range of drugs. Although clinically approved nanoparticles have consistently shown value in reducing drug toxicity, their use has not always translated into improved clinical outcomes. This has led to the development of "multifunctional" nanoparticles, where additional capabilities like targeting and image contrast enhancement are added to the nanoparticles. However, additional functionality means additional synthetic steps and costs, more convoluted behavior and effects in vivo, and also greater regulatory hurdles. The trade-off between additional functionality and complexity is the subject of ongoing debate and the focus of this Review.

X-ROS signaling: rapid mechano-chemo transduction in heart

We report that in heart cells, physiologic stretch rapidly activates reduced-form nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) to produce reactive oxygen species (ROS) in a process dependent on microtubules (X-ROS signaling). ROS production occurs in the sarcolemmal and t-tubule membranes where NOX2 is located and sensitizes nearby ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR). This triggers a burst of Ca(2+) sparks, the elementary Ca(2+) release events in heart. Although this stretch-dependent "tuning" of RyRs increases Ca(2+) signaling sensitivity in healthy cardiomyocytes, in disease it enables Ca(2+) sparks to trigger arrhythmogenic Ca(2+) waves. In the mouse model of Duchenne muscular dystrophy, hyperactive X-ROS signaling contributes to cardiomyopathy through aberrant Ca(2+) release from the SR. X-ROS signaling thus provides a mechanistic explanation for the mechanotransduction of Ca(2+) release in the heart and offers fresh therapeutic possibilities.

Evaluation of role of angiotensin III and aminopeptidases in prostate cancer cells

BACKGROUND

The aim of this study was to perform a comprehensive evaluation of angiotensin III (Ang-III) and related converting enzymes, aminopeptidase A (APA) and N (APN), in prostate cancer.

METHODS

We investigated the effects of Ang-III on the in vitro growth of human prostate cancer cells and the expression of APA and APN in cells treated with Ang-III or hormonal agents. Furthermore, we performed real-time quantitative PCR to investigate the expression pattern of APA and APN in 86 prostate tissue samples including normal prostate, untreated and hormone refractory prostate cancer (HRPC).

RESULTS

Ang-III stimulated cell proliferation, and the proliferative effect was inhibited by olmesartan, an AT(1) receptor blocker (ARB). Western blot analysis showed that phosphorylation of mitogen-activated protein kinase (MAPK) was enhanced by Ang-III and inhibited by olmesartan. APN mRNA level in HRPC was significantly lower than that in normal prostate and untreated prostate cancer tissue. In LNCaP cells, APN expression was augmented by Ang-III, whereas APA expression was not modulated. Hormonal agents, such as estradiol (E2) and dexamethasone (Dex), enhanced APA expression, but did not modulate APN expression in LNCaP cells.

CONCLUSIONS

Our results suggest that Ang-III and related converting enzymes contribute to cell proliferation of prostate cancer, and may be implicated in cancer progression.

Manipulating the angiotensin system--new approaches to the treatment of solid tumours

Angiotensin II (Ang II), a main effector peptide in the renin-angiotensin system (RAS), plays a fundamental role as a vasoconstrictor in controlling cardiovascular function and renal homeostasis. Ang II also acts as a growth promoter or angiogenic factor via type 1 angiotensin II receptors (AT1Rs) in certain tumour cell lines. Recent studies have shown the activation of the local RAS in various tumour tissues, including the abundant generation of Ang II by angiotensin-converting enzyme (ACE) and the upregulation of AT1R expression. Thus, considerable attention has been paid to the role of the RAS in cancer and its blockade as a new approach to the treatment of cancer. There is increasing evidence that the Ang II-AT1R system is involved in tumour growth, angiogenesis and metastasis in experimental models, suggesting the therapeutic potential of an ACE inhibitor and AT1R blocker, both of which have been used as antihypertensive drugs. In addition, specific Ang II-degrading enzymes are expressed in tumours and play a regulatory role in cell proliferation and invasion. This review focuses on the role of the Ang II-AT1R system in solid tumours, particularly in the progression of gynaecological cancer, and presents the clinical potential of manipulating the angiotensin system as a novel and promising strategy for cancer treatment.

Angiotensin II type 1 receptor expression in ovarian cancer and its correlation with tumour angiogenesis and patient survival

Angiotensin II, a main effector peptide in the renin–angiotensin system, acts as a growth-promoting and angiogenic factor via type 1 angiotensin II receptors (AT₁R). We have recently demonstrated that angiotensin II enhanced tumour cell invasion and vascular endothelial growth factor (VEGF) secretion via AT₁R in ovarian cancer cell lines in vitro. The aim of the present study was to determine whether AT₁R expression in ovarian cancer is correlated with clinicopathological parameters, angiogenic factors and patient survival. Immunohistochemical staining for AT₁R, VEGF, CD34 and proliferating cell nuclear antigen (PCNA) were analysed in ovarian cancer tissues (n=67). Intratumour microvessel density (MVD) was analysed by counting the CD34-positive endothelial cells. Type 1 angiotensin II receptors were expressed in 85% of the cases examined, of which 55% were strongly positive. Type 1 angiotensin II receptors expression was positively correlated with VEGF expression intensity and MVD, but not with histological subtype, grade, FIGO stage or PCNA labelling index. In patients who had positive staining for AT₁R, the overall survival and progression-free survival were significantly poor (P=0.041 and 0.017, respectively) as compared to those in patients who had negative staining for AT₁R, although VEGF, but not AT₁R, was an independent prognostic factor on multivariate analysis. These results demonstrated that AT₁R correlated with tumour angiogenesis and poor patient outcome in ovarian cancer, suggesting its clinical potential for a novel molecular target in strategies for ovarian cancer treatment.

eIF4E as a Marker for Cervical Neoplasia

Eukaryotic translation initiation factor 4E (eIF4E) is upregulated in cancers of the breast and head and neck. The authors have shown that eIF4E is increased in cervical neoplasia and that eIF4E upregulates human papillomavirus (HPV) oncoprotein E7. The aim of this study was to quantitate eIF4E in tissues representing a wide range of cervical pathology. The potential correlation between dysplastic grade or tumor stage with eIF4E upregulation and/or HPV genotype was analyzed for 10 normal, 27 cancer, and 37 dysplasia cases. A progressive increase in eIF4E staining intensity was found with increasing cervical pathology (P < 0.0001). No difference was seen in eIF4E stain intensity by either tumor type--squamous cell cancer (n = 18), adenocarcinoma (n = 4), or other types of cancer (n = 5) (P = 0.97)--or by tumor grade--II (n = 5) versus III (n = 7). Likewise, neither an HPV typing result of HPV 16 (n = 10) versus non-HPV 16 (n = 4) nor single HPV infection (n = 11) versus dual HPV infection (n = 3) significantly altered the eIF4E stain results (P = 0.86 and 0.97, respectively). These results indicate that eIF4E stain intensity may be useful as a marker for cervical neoplasia.

Possible Involvement of Adipocyte-Derived Leucine Aminopeptidase via Angiotensin II in Endometrial Carcinoma

OBJECTIVE

It has recently been appreciated that a local autocrine or paracrine renin-angiotensin system (RAS) may exist in a number of tissues. Angiotensin II (AngII) is a potent RAS-derived vasoconstrictor peptide, and it is involved in tumor angiogenesis. We have cloned human adipocyte-derived leucine aminopeptidase (A-LAP), which degrades Ang II. This study investigated whether the expression of A-LAP, Ang II, angiotensin type I receptor (AT1R) and vascular endothelial growth factor (VEGF) correlates with clinicopathologic factors and prognosis in patients with endometrial endometrioid adenocarcinoma.

METHODS

Histologic sections of formalin-fixed, paraffin-embedded specimens from 94 primary endometrial carcinomas were stained for A-LAP, AngII, AT1R and VEGF using each antibody. Disease-free survival (DFS) and other clinicopathologic characteristics were analyzed according to the intensity of each staining.

RESULTS

Of 94 cases, 91 (96.8%) showed specific A-LAP immunostaining. A-LAP expression demonstrated negative correlations with myometrial invasion (p = 0.01) and vascular infiltration (p = 0.01). Of 94 cases, 77 (81.9%) showed specific AngII immunostaining. We found a positive correlation between AngII expression and surgical stage (p = 0.01). Of 94 cases, 56 (59.6%) showed specific AT1R immunostaining and 73 (77.7%) specific VEGF immunostaining. We found a positive correlation between VEGF expression and lymph node metastasis (p = 0.05). AngII and AT1R expression predicted a significantly poorer prognosis. Contrarily, A-LAP expression indicated a significantly more favorable prognosis in endometrial endometrioid adenocarcinoma patients. Multivariate analysis demonstrated that A-LAP expression (odds ratio, 0.12; 95% confidence interval, 0.025-0.618; p = 0.01) was an independent prognostic factor.

CONCLUSIONS

In this study, we demonstrated the existence of local RAS and A-LAP in endometrial endometrioid adenocarcinoma as prognostic predictors of clinical outcome. These findings suggest that the assessment of RAS and A-LAP status provides clinically useful prognostic information in patients with endometrial carcinoma.

Chemopreventive n-3 polyunsaturated fatty acids reprogram genetic signatures during colon cancer initiation and progression in the rat

The mechanisms by which n-3 polyunsaturated fatty acids (PUFAs) decrease colon tumor formation have not been fully elucidated. Examination of genes up- or down-regulated at various stages of tumor development via the monitoring of gene expression relationships will help to determine the biological processes ultimately responsible for the protective effects of n-3 PUFA. Therefore, using a 3 x 2 x 2 factorial design, we used Codelink DNA microarrays containing approximately 9000 genes to help decipher the global changes in colonocyte gene expression profiles in carcinogen-injected Sprague Dawley rats. Animals were assigned to three dietary treatments differing only in the type of fat (corn oil/n-6 PUFA, fish oil/n-3 PUFA, or olive oil/n-9 monounsaturated fatty acid), two treatments (injection with the carcinogen azoxymethane or with saline), and two time points (12 hours and 10 weeks after first injection). Only the consumption of n-3 PUFA exerted a protective effect at the initiation (DNA adduct formation) and promotional (aberrant crypt foci) stages. Importantly, microarray analysis of colonocyte gene expression profiles discerned fundamental differences among animals treated with n-3 PUFA at both the 12 hours and 10-week time points. Thus, in addition to demonstrating that dietary fat composition alters the molecular portrait of gene expression profiles in the colonic epithelium at both the initiation and promotional stages of tumor development, these findings indicate that the chemopreventive effect of fish oil is due to the direct action of n-3 PUFA and not to a reduction in the content of n-6 PUFA.

Expression of placental leucine aminopeptidase is associated with a poor outcome in endometrial endometrioid adenocarcinoma

OBJECTIVE

Placental leucine aminopeptidase (P-LAP) is a cell surface aminopeptidase (oxytocinase). We cloned P-LAP cDNA and found a widespread tissue distribution of P-LAP. Since P-LAP can degrade several small peptide hormones such as oxytocin, this enzyme may affect many cellular functions of carcinoma cells as well as normal cells. This study investigated whether the expression of P-LAP correlates with clinicopathologic factors and prognosis in patients with endometrial endometrioid adenocarcinoma.

METHODS

Histologic sections of formalin-fixed, paraffin-embedded specimens from 99 primary endometrial carcinomas were stained for P-LAP using polyclonal P-LAP antibody. Disease-free survival and other clinicopathologic characteristics were analyzed according to the intensity of P-LAP staining.

RESULTS

Of 99 cases, 69 (69.7%) showed specific P-LAP immunostaining. We found a positive correlation between the expression of P-LAP and histological grade (p < 0.01), surgical stage of the disease (p = 0.02), myometrial invasion (p = 0.01), lymph node involvement (p < 0.01), and vascular infiltration (p < 0.01). In patients who had strongly positive P-LAP staining, the disease-free interval was significantly lower than in patients who had negative or weakly positive P-LAP staining (p < 0.01). Multivariate analysis demonstrated that strongly immunoreactive P-LAP (odds ratio, 12.8; 95% confidence interval, 2.84-58.8; p < 0.01) and surgical stage (odds ratio, 8.78; 95% confidence interval, 2.77-27.8; p < 0.01) are independent prognostic factors.

CONCLUSIONS

This study suggests P-LAP as an independent prognosticator of clinical outcome in patients with endometrial carcinoma. Therefore, assessment of the P-LAP status provides clinically useful prognostic information in patients with endometrial carcinoma.

Activation of invasiveness of cervical carcinoma cells by angiotensin II

OBJECTIVE

Angiotensin II recently has been reported to promote the growth of several kinds of cells. In this study, we investigated the effect of angiotensin II on cervical carcinoma cells.

STUDY DESIGN

The expression of angiotensin II type I receptor was examined by immunohistochemistry in normal and neoplastic cervical tissues. Invasion assay was examined in Siha cells (cervical squamous cell carcinoma) and vascular endothelial growth factor levels were assayed with a vascular endothelial growth factor enzyme-linked immunosorbent assay kit.

RESULTS

Mean staining intensity level was stronger in invasive carcinoma cells than in normal, dysplasia, and carcinoma in situ tissues. Angiotensin II induced the secretion of vascular endothelial growth factor from Siha cells. Furthermore, angiotensin II promoted the invasive potential of Siha cells. These effects were reversed by the addition of anti-human vascular endothelial growth factor antibody and candesartan (antagonist of angiotensin II type I receptor).

CONCLUSION

Angiotensin II is involved in the progression of cervical carcinoma, because it induces the secretion of vascular endothelial growth factor through angiotensin II type I receptor, which results in the increased invasiveness of carcinoma cells.

Regulation of aminopeptidase A expression in cervical carcinoma: role of tumor-stromal interaction and vascular endothelial growth factor

We previously demonstrated that aminopeptidase A (APA), a membrane-bound metallopeptidase degrading bioactive peptides such as angiotensin II (Ang II), is expressed in neoplastic lesions of the uterine cervix, and that its expression is upregulated as the lesion progresses from cervical intraepithelial neoplasms (CIN) toward invasive squamous cell carcinomas (SCC). The present study investigated the regulatory mechanisms involved in APA expression and its potential role in cervical carcinoma. Immunohistochemical staining in high-grade CIN and SCC tissues showed that APA was strongly expressed at the edge of lesions adjacent to cervical stromal cells. Fluorescence-activated cell sorting analysis demonstrated that cell surface APA expression was extremely low in three human SCC cell lines, SiHa, TCS and CaSki, under basal conditions. However, both contact and noncontact cocultures with human cervical fibroblasts resulted in the induction of APA expression in these SCC cells. APA expression was also induced in vivo when TCS cells were subcutaneously inoculated into nude mice. Furthermore, APA expression and enzymatic activity were enhanced by addition of the conditioned medium (CM) from fibroblast culture, but not by heat-treated CM. Among the various cytokines tested, vascular endothelial growth factor (VEGF) significantly increased APA activity, and induction of APA by the fibroblast CM was partly inhibited by anti-VEGF neutralizing antibody. Finally, APA cDNA-transfected APA-overexpressing TCS cells significantly reduced the Ang II-induced cell invasion ability as compared with parental or control vector-transfected TCS cells, although there was no significant difference in cellular proliferation among them. These results suggested the importance of tumor-stromal interaction for the regulation of APA expression in the microenvironment of cervical carcinoma and the potential role for this peptidase in regulating tumor invasion through inactivation of Ang II activity.

Aminopeptidase A is a functional target in angiogenic blood vessels

We show that a membrane-associated protease, aminopeptidase A (APA), is upregulated and enzymatically active in blood vessels of human tumors. To gain mechanistic insight, we evaluated angiogenesis in APA null mice. We found that, although these mice develop normally, they fail to mount the expected angiogenic response to hypoxia or growth factors. We then isolated peptide inhibitors of APA from a peptide library and show that they specifically bind to and inhibit APA, suppress migration and proliferation of endothelial cells, inhibit angiogenesis, and home to tumor blood vessels. Finally, we successfully treated tumor-bearing mice with APA binding peptides or anti-APA blocking monoclonal antibodies. These data show that APA is a regulator of blood vessel formation, and can serve as a functional vascular target.

Regulatory role of membrane-bound peptidases in the progression of gynecologic malignancies

Membrane-bound peptidases play a key role in the control of growth, differentiation, and signal transduction of many cellular systems by degrading bioactive peptides. Thus, abnormal changes in their expression pattern and catalytic function result in altered peptide activation, which contributes to neoplastic transformation or progression. In this review, we describe our recent findings along with work from other groups on the expression and biological functions of membrane-bound peptidases in cancer, focusing on the regulatory roles of three peptidases, aminopeptidase A (APA), neutral endopeptidase (NEP) and placental leucine aminopeptidase (P-LAP), in the progression of gynecologic malignancies. APA, NEP and P-LAP are differentially expressed and localized in various gynecologic malignancies including cervical cancer, endometrial cancer, ovarian cancer and choriocarcinoma in a tumor-type specific pattern. The expression levels are up- or down-regulated depending on histological grade or disease progression. These peptidases play regulatory roles in tumor cell proliferation, invasion or angiogenesis via degradation/inactivation of target peptides such as angiotensin II, endothelin-1 and oxytocin, which act on cancer cells as stimulatory or inhibitory factors. Thus, membrane-bound peptidases may become not only a new diagnostic/prognostic marker, but also a novel molecular target for the treatment of gynecologic malignancies.

Dipeptidyl peptidase IV expression in endometrial endometrioid adenocarcinoma and its inverse correlation with tumor grade

OBJECTIVES

Dipeptidyl peptidase IV (DPPIV)/CD26 is a cell surface aminopeptidase. This study investigated the expression and localization of DPPIV in endometrial endometrioid adenocarcinomas of different grades.

STUDY DESIGN

Immunohistochemical analysis was performed by using DPPIV and regulated on activation, normal T-cell expressed and secreted (RANTES) specific monoclonal antibodies. Cell proliferation was evaluated by bromodeoxyuridine (BrdU) uptake assay.

RESULTS

Immunohistochemical analyses showed that DPPIV was strongly or moderately stained in glandular cells of the normal secretory phase. In endometrial adenocarcinoma, the DPPIV expression decreased with advancing grade (P <.01). Furthermore, RANTES, one of the possible DPPIV substrates, was highly expressed in all grades of endometrial adenocarcinoma cells. The addition of RANTES to endometrial adenocarcinoma cells increased proliferation in a concentration-dependent manner.

CONCLUSION

DPPIV is expressed in normal endometrial glandular cells, but its expression in endometrial adenocarcinoma is down-regulated with increasing grade. Our data also suggest a regulatory role of this ectoenzyme in neoplastic transformation and progression of endometrial adenocarcinomas possibly by degrading certain bioactive peptides such as RANTES.

Differential distribution of placental leucine aminopeptidase/oxytocinase and aminopeptidase A in human trophoblasts of normal placenta and complete hydatidiform mole

Placental leucine aminopeptidase (P-LAP)/oxytocinase (OTase) degrades several small peptides such as oxytocin (OT), arginine vasopressin (AVP) and angiotensin III (ANGIII), and aminopeptidase A (AP-A) converts angiotensin II (ANGII) to ANGIII. These proteases play an important role in foetal growth and the maintenance of human homeostasis during pregnancy. In this study, we confirmed the distribution of P-LAP and AP-A proteins and messenger RNAs in human trophoblasts in normal placenta and complete hydatidiform mole by immunohistochemical and in-situ hybridization techniques. Immunoreactivity of P-LAP was mainly noted in the apical membrane of syncytiotrophoblasts, and the expression of messenger RNA (mRNA) for P-LAP was predominantly noted in the cytoplasm of syncytiotrophoblastic cells. However, immunoreactivity of AP-A was mainly noted in the apical membrane of cytotrophoblasts and in the basal zone of the syncytiotrophoblasts, and the expression of mRNA for AP-A was predominantly noted in cytoplasm of cytotrophoblastic cells and a little in cytoplasm of syncytiotrophoblastic cells. Thereby, the two proteases were differentially distributed both in normal placenta and hydatidiform mole throughout the gestational age. These results are useful for the further understanding of not only the pathophysiology of pregnancy, but also the pathogenesis of trophoblastic diseases.

Imbalance between neutral endopeptidase 24.11 and endothelin-1 expression in human endometrial carcinoma

OBJECTIVES

Neutral endopeptidase 24.11 (NEP)/CD10 is a cell-surface peptidase that degrades various bioactive peptides including endothelin-1 (ET-1). This enzyme is known to play a role in maintaining ET-1-regulated vascular homeostasis in the normal human endometrium. The purpose of the present study was to investigate the expression and localization of NEP and ET-1 in neoplastic endometria, and also to clarify the correlation of their expression with the tumor grade of endometrial carcinoma.

METHODS

Immunohistochemical analysis for NEP and ET-1 expression was performed on paraffin-embedded tissue sections of 7 normal endometria (after menopause), 5 atypical endometrial hyperplasias (AEH), and 32 endometrial endometrioid adenocarcinomas.

RESULTS

In normal endometrium and AEH, NEP immunoreactivity was detected in stromal cells, but not in glandular cells. In contrast, ET-1 immunoreactivity was detected in both glandular and stromal cells. In the stromal cells of grade 1 endometrial adenocarcinoma, NEP was detected at high or moderate quantities. However, significantly decreased NEP immunoreactivity was observed in the stromal cells of grade 2 and 3 adenocarcinomas. However, NEP was not immunostained in adenocarcinoma cells except for the lesions of squamous differentiation. ET-1 immunoreactivity was weakly detected in the stromal cells of grade 1 adenocarcinoma, but the intensity of ET-1 staining increased with advancing tumor grade. The ratio of the staining scores of stromal ET-1 to stromal NEP was positively correlated with the tumor grade.

CONCLUSIONS

These findings demonstrate that NEP expression in the stromal cells of endometrial adenocarcinoma is downregulated, while stromal ET-1 is upregulated, with increasing tumor grade. The present findings also suggest that NEP may play a role in the regulation of neoplastic transformation, tumor progression, and differentiation in endometrial neoplasms, possibly by degrading certain peptide growth factors such as ET-1.

Identification of novel hypoxia dependent and independent target genes of the von Hippel-Lindau (VHL) tumour suppressor by mRNA differential expression profiling

The von Hippel-Lindau tumour suppressor gene (VHL) targets hypoxia inducible factor (HIF)-alpha subunits for ubiquitin dependent proteolysis. To better understand the role of this and other putative pathways of gene regulation in VHL function we subjected mRNA from VHL defective renal carcinoma cells and transfectants re-expressing a wild type VHL allele to differential expression profiling, and analysed VHL target genes for oxygen regulated expression. Among a group of newly identified VHL target genes the majority but not all were regulated by oxygen, indicating that whilst dysregulation of the HIF system makes a dominant contribution to alterations in transcription, VHL has other influences on patterns of gene expression. Genes newly defined as targets of the VHL/hypoxia pathway (conditionally downregulated by VHL in normoxic cells) include aminopeptidase A, collagen type V, alpha 1, cyclin G2, DEC1/Stra13, endothelin 1, low density lipoprotein receptor-related protein 1, MIC2/CD99, and transglutaminase 2. These genes have a variety of functions relevant to tumour biology. However, not all are connected with the promotion of tumour growth, some being pro-apoptotic or growth inhibitory. We postulate that co-ordinate regulation as part of the HIF pathway may explain this paradox, and that evolution of anti-apoptotic pathways may be required for tumour growth under VHL-dysregulation. Our results indicate that it will be necessary to consider the effects of abnormal activity in integral regulatory pathways, as well as the effects of individual genes to understand the role of abnormal patterns of gene expression in cancer.

The expression and localization of neutral endopeptidase 24.11/CD10 in human gestational trophoblastic diseases

Neutral endopeptidase 24.11 (NEP)/CD10 is a cell-surface peptidase that hydrolyzes various bioactive peptides. NEP is distributed in both normal and neoplastic cells and plays a functional role by modulating cellular responses to peptide substrates. Recently, NEP has been shown to be expressed in normal placental trophoblasts, suggesting its physiological role during pregnancy. In the present study, we investigated the expression of NEP in hyperplastic and anaplastic trophoblasts in gestational trophoblastic diseases (GTDs). Flow cytometric analysis demonstrated that NEP was expressed in all choriocarcinoma cell lines examined. The NEP enzyme activity in these cell lines correlated with cell-surface protein levels and was abolished by the NEP inhibitor phosphoramidon. On immunoblot analysis, NEP protein was detected in both hydatidiform mole and choriocarcinoma tissues as a double band of 95 and 100 kDa similar to that of the normal placental tissues. Immunohistochemical analysis revealed that NEP was present on syncytiotrophoblasts, while no or very faint NEP immunoreactivity was observed on cytotrophoblasts in the normal placenta. Similarly, NEP in hydatidiform mole and invasive mole was localized on the membrane of syncytiotrophoblasts, but not on hyperplastic cytotrophoblasts. In contrast, in choriocarcinoma, NEP was highly expressed not only on syncytiotrophoblastic cells but also on invading anaplastic cytotrophoblasts. In addition, NEP was also expressed on intermediate trophoblasts in placental site trophoblastic tumors. In summary, this is the first study demonstrating the expression of NEP/CD10 in GTDs. The differential localization of NEP among various trophoblastic tumors suggests that NEP may play a functional role in the regulation of trophoblast transformation and human chorionic gonadotropin secretion.