The type 1 CD10/neutral endopeptidase 24.11 promoter: functional characterization of the 5′-untranslated region

Identification and functional characterization of pVHL-dependent cell surface proteins in renal cell carcinoma

The identification of cell surface accessible biomarkers enabling diagnosis, disease monitoring, and treatment of renal cell carcinoma (RCC) is as challenging as the biology and progression of RCC is unpredictable. A hallmark of most RCC is the loss-of-function of the von Hippel-Lindau (pVHL) protein by mutation of its gene (VHL). Using the cell surface capturing (CSC) technology, we screened and identified cell surface N-glycoproteins in pVHL-negative and positive 786-O cells. One hundred six cell surface N-glycoproteins were identified. Stable isotope labeling with amino acids in cell culture-based quantification of the CSC screen revealed 23 N-glycoproteins whose abundance seemed to change in a pVHL-dependent manner. Targeted validation experiments using transcriptional profiling of primary RCC samples revealed that nine glycoproteins, including CD10 and AXL, could be directly linked to pVHL-mediated transcriptional regulation. Subsequent human tumor tissue analysis of these cell surface candidate markers showed a correlation between epithelial AXL expression and aggressive tumor phenotype, indicating that pVHL-dependent regulation of glycoproteins may influence the biologic behavior of RCC. Functional characterization of the metalloprotease CD10 in cell invasion assays demonstrated a diminished penetrating behavior of pVHL-negative 786-O cells on treatment with the CD10-specific inhibitor thiorphan. Our proteomic surfaceome screening approach in combination with transcriptional profiling and functional validation suggests pVHL-dependent cell surface glycoproteins as potential diagnostic markers for therapeutic targeting and RCC patient monitoring.

Dense methylation of types 1 and 2 regulatory regions of the CD10 gene promoter in infant acute lymphoblastic leukemia with MLL/AF4 fusion gene

Infant acute lymphoblastic leukemia (ALL) displays distinct biologic and clinical features with a poor prognosis. The CD10-negative immunophenotype of infant ALL is a hallmark and provides a predictable signature of mixed-lineage leukemia (MLL) rearrangement. Although CD10 negativity reflects an earlier stage of B-cell development, complete IgH gene rearrangements (VDJH), found in almost half of the patients, show more mature IgH status. Discordance between immunophenotype and genotype of infant ALL suggests an aberrant process in immunophenotypic steps of differentiation or a secondary down-regulation of CD10 expression. In this study, CD10-negative infant ALL with MLL/AF4, CD10-positive infant ALL with germline MLL, CD10-positive pre-B ALL cell line, infant acute myeloid leukemia (AML; M5) with MLL/AF9 and pediatric AML (M2) with AML1/ETO were analyzed for VDJH status and methylation of CD10 gene promoters. Three of the 4 infant ALL samples showed complete rearrangements of the VDJH gene with productive joints. Bisulfite sequencing of CD10 type 1 and 2 promoters showed that more than 84% of the cytosine-phosphate-guanine (CpG) dinucleotides identified were methylated in all 3 CD10-negative infant ALL samples with MLL/AF4. The CpG dinucleotides distributed in the clusters of putative Sp1-binding sites and functionally active regulatory regions of the promoters were fully methylated. In contrast, none of the CpG dinucleotides were methylated in the CD10-positive ALL samples. Structural evidence of dense methylation in the CD10 gene promoter suggested that methylated transcription factor binding sites contribute to CD10 silencing as an epigenetic mechanism.

Down-regulation of neprilysin (EC3.4.24.11) expression in vascular endothelial cells by laminar shear stress involves NADPH oxidase-dependent ROS production

Neprilysin (NEP, neutral endopeptidase, EC3.4.24.11), a zinc metallopeptidase expressed on the surface of endothelial cells, influences vascular homeostasis primarily through regulated inactivation of natriuretic peptides and bradykinin. Earlier in vivo studies reporting on the anti-atherosclerotic effects of NEP inhibition and on the atheroprotective effects of flow-associated laminar shear stress (LSS) have lead us to hypothesize that the latter hemodynamic stimulus may serve to down-regulate NEP levels within the vascular endothelium. To address this hypothesis, we have undertaken an investigation of the effects of LSS on NEP expression in vitro in bovine aortic endothelial cells (BAECs), coupled with an examination of the signalling mechanism putatively mediating these effects. BAECs were exposed to physiological levels of LSS (10 dynes/cm(2), 24h) and harvested for analysis of NEP expression using real-time PCR, Western blotting, and immunocytochemistry. Relative to unsheared controls, NEP mRNA and protein were substantially down-regulated by LSS (>or=50%), events which could be prevented by treatment of BAECs with either N-acetylcysteine, superoxide dismutase, or catalase, implicating reactive oxygen species (ROS) involvement. Employing pharmacological and molecular inhibition strategies, the signal transduction pathway mediating shear-dependent NEP suppression was also examined, and roles implicated for G beta gamma, Rac1, and NADPH oxidase activation in these events. Treatment of static BAECs with angiotensin-II, a potent stimulus for NADPH oxidase activation, mimicked the suppressive effects of shear on NEP expression, further supporting a role for NADPH oxidase-dependent ROS production. Interestingly, inhibition of receptor tyrosine kinase signalling had no effect. In conclusion, we confirm for the first time that NEP expression is down-regulated in vascular endothelial cells by physiological laminar shear, possibly via a mechanotransduction mechanism involving NADPH oxidase-induced ROS production.

Genetic variation in the natriuretic peptide system and heart failure

Heart failure (HF) is a modern epidemic and is one of the few cardiovascular diseases which is increasing in prevalence. The growing importance of the Natriuretic Peptide (NP) system in HF is well recognized. Laboratory tests for B-type Natriuretic Peptide (BNP) have proven value as diagnostic and prognostic tools in HF and are now part of routine clinical care. Furthermore, recombinant atrial natriuretic peptide (ANP) (carperitide) and BNP (nesiritide) and are approved HF therapies in Japan and the US, respectively and additional natriuretic peptides (e.g., CNP, urodilatin, and designer NPs) are under investigation for use in HF. Common genetic sequence variants are increasingly being recognized as determinants of disease risk or drug response and may help explain a portion of the inter-individual variation in the human NP system. This review describes current knowledge of NP system genetic variation as it pertains to HF as well as ongoing studies and where the field is expected to progress in the near future. To briefly summarize, NP system genetic variants have been associated with alterations in gene expression, NP levels, and cardiovascular disease. The next step forward will include specific investigations into how this genetic variation can advance 'Personalized Medicine', such as whether they impact the utility of diagnostic BNP testing or effectiveness of therapeutic NP infusion. This is already in progress, with pharmacogenetic studies of nesiritide currently underway. We expect that within 5 years there should be a reasonable idea of whether NP system genetic variation will have important clinical implications.

Multiple androgen response elements cooperate in androgen regulated activity of the type 1 neutral endopeptidase promoter

The neutral endopeptidase (NEP) gene is transcriptionally regulated by androgen in prostate cancer cells. We previously identified in the NEP gene an androgen responsive element (NEP-ARE) and an androgen responsive region (NEP-ARR) that together conveyed only moderate androgen-inducibility [Mol. Cell. Endocrinol. 170 (2000) 131]. Therefore, we characterized the entire genomic structure of the NEP gene and identified ARE1 (ACTCAACAttgTGTCCTTT) and ARE2 (CAGGACAtttTGTCCC), which are located in the 3'-untranslated region and in intron 17, respectively. Steroid-dependent enhancement of transcription was assayed by transfecting the pGL-3-luciferase reporter plasmid containing three copies of ARE1 or ARE2 into PC-3 cells. Luciferase activities were increased 3.6-fold (ARE1) and 5-fold (ARE2) by androgen (AR), 4.2-fold (ARE1) and 8.2-fold (ARE2) by dexamethasone, and 3-fold (ARE1) and 4.1-fold (ARE2) by progesterone. Mutation of the ARE1 and ARE2 sequences completely abrogated androgen-inducibility. We next showed that both ARE1 and ARE2 are involved in the transcriptional regulation of the NEP gene, demonstrating in vitro and in vivo binding with AR as determined by electrophoretic mobility gel shift and chromatin immunoprecipitation (ChIP) assays, Furthermore, ARE1 and ARE2 mediate coordinated androgen-inducibility in both an SV40 promoter and the native NEP type 1 promoter. These data indicate the newly identified ARE1 and ARE2 together with the previously identified NEP-ARE function as androgen response elements, and that androgen regulation of the NEP gene is regulated by the coordinated action of multiple AREs in prostate cancer cells.

CD10 expression in trichoepithelioma and basal cell carcinoma

BACKGROUND

Trichoepithelioma (TE) is a benign neoplasm that shares both clinical and histologic features with basal cell carcinoma (BCC). However, it is important to distinguish these neoplasms. Limited immunohistochemical stains are available to separate these two tumors.

METHODS

CD10 protein immunohistochemistry was performed on paraffin-embedded biopsies of 13 TE and 23 BCC diagnosed by routine microscopy. Cases were analyzed for pattern of CD10 expression by tumor cells and surrounding stroma.

RESULTS

Twelve of 13 (92%) TE showed positive stromal immunoreactivity. Of these, eight cases also demonstrated positivity of the papilla, and two also showed positivity of the basaloid cells. No TE demonstrated epithelial expression alone. On the other hand, expression of CD10 by basaloid cells was identified in 20 (87%) cases of BCC. Stromal positivity was also identified in three cases of BCC. Condensation of CD10-positive stromal cells around basaloid nests was statistically significant in differentiating TE from BCC (p < 0.0001). Conversely, CD10-positive basaloid cells were seen predominantly in BCC (p < 0.0001).

CONCLUSIONS

This study demonstrates a statistically significant difference in CD10 staining pattern between TE and BCC. Thus, CD10 may be a useful adjunct marker in distinguishing these tumors.

Elevated hepatocyte paraffin 1 and neprilysin expression in hepatocellular carcinoma are correlated with longer survival

Hepatocyte paraffin 1 (Hep Par 1) and neprilysin (CD10) are well-known markers of hepatocellular carcinoma (HCC). To assess their potential prognostic role, we conducted a retrospective analysis of 97 formalin-fixed and paraffin-embedded HCC from patients treated by surgery with curative intent, using standard immunohistochemical procedures and semiquantitative analysis. Strong Hep Par 1 expression and canalicular CD10 staining pattern were significantly correlated with smaller tumor size (p=0.007 and 0.04, respectively). On univariate analysis, longer overall survival was observed in patients with strong Hep Par 1 expression (p=0.0005) and in patients with a CD10can staining pattern (p=0.02). On multivariate analysis, the combined immunohistochemical score (CIS) obtained by addition of Hep Par 1 and CD10can scores and subtraction of cytoplasmic CD10 score was retained as the single most important prognostic factor (p=0.001). Patients with a CIS <4 had a 3.5-fold increased risk of death, as compared to those with a CIS >or=4. In conclusion, strong Hep Par 1 expression, presence of CD10can labeling, and absence of CD10cyt staining are favorable prognostic factors in HCC, which can be easily combined into a single immunohistochemical score for routine clinical use.

Metabolism of amyloid-beta peptide and Alzheimer's disease

The accumulation of amyloid-beta peptide (Abeta), a physiological peptide, in the brain is a triggering event leading to the pathological cascade of Alzheimer's disease (AD) and appears to be caused by an increase in the anabolic activity, as seen in familial AD cases or by a decrease in catabolic activity. Neprilysin is a rate-limiting peptidase involved in the physiological degradation of Abeta in the brain. As demonstrated by reverse genetics studies, disruption of the neprilysin gene causes elevation of endogenous Abeta levels in mouse brain in a gene-dose-dependent manner. Thus, the reduction of neprilysin activity will contribute to Abeta accumulation and consequently to AD development. Evidence that neprilysin in the hippocampus and cerebral cortex is down-regulated with aging and from an early stage of AD development supports a close association of neprilysin with the etiology and pathogenesis of AD. Therefore, the up-regulation of neprilysin represents a promising strategy for therapy and prevention. Recently, somatostatin, which acts via a G-protein-coupled receptor (GPCR), has been identified as a modulator that increases brain neprilysin activity, resulting in a decrease of Abeta levels. Thus, it may be possible to pharmacologically control brain Abeta levels with somatostatin receptor agonists.

Sp1 elements inSULT2B1bpromoter and 5′-untranslated region of mRNA: Sp1/Sp2 induction and augmentation by histone deacetylase inhibition

The steroid/sterol sulfotransferase gene (SULT2B1) encodes for two isozymes of which one (SULT2B1b) sulfonates cholesterol and is selectively expressed in skin. The human SULT2B1 gene contains neither a TATAAA nor a CCAAT motif upstream of the coding region for SULT2B1b; however, this area is GC-rich. Of five Sp1 elements identified two had regulatory activity utilizing immortalized human keratinocytes: one element is located above the ostensible transcription initiation site, whereas the other is located within the 5'-untranslated region of the SULT2B1b mRNA. Sp1 and Sp2 transcription factors identified by supershift analyses induced reporter gene activity, an effect markedly augmented by histone deacetylase inhibition.

Mixed gastric- and intestinal-type metaplasia is formed by cells with dual intestinal and gastric differentiation

We have proposed to divide intestinal metaplasia (IM) into two categories, i.e., a mixed gastric and intestinal (GI) type, and a solely intestinal (I) type, based on the residual gastric phenotype cells. The GI-mixed-type IM can be identified by the presence of both cells with either gastric or intestinal phenotypes in a single gland. This study is conducted to elucidate whether cells in the GI-mixed-type IM glands can simultaneously present both gastric and intestinal phenotypes. MUC5AC, MUC2, CD10 and villin expressions were investigated in 20 samples from five gastric cancer cases, directly using either AlexaFluor 488- or 568-labeled specific monoclonal antibodies and observed by fluorescent microscopy and confocal laser-scanning microscopy. GI-mixed IM glands comprise a population expressing MUC5AC and MUC2, MUC5AC and villin, and MUC5AC and CD10. MUC2 and villin expressions were reciprocally increased with decreasing MUC5AC expression, while CD10 expression was limited to cells with only a residual MUC5AC expression or no expression. These results suggest that a heterogeneous cell population with both gastric and intestinal phenotypes would develop into a single intestinal phenotype, as reflected in the progression of intestinal metaplasia from GI-mixed-type- to I-type IM-type glands.