Differential expression of the human alpha-enolase gene in oral epithelium and squamous cell carcinoma

Generation and characterization of avian single chain variable fragment against human Alpha-Enolase

Overexpression of human alpha-enolase (hEno1)has been reported in a wide range of cancers and is tightly associated with poor prognosis, making it a remarkable biomarker and therapeutic target. In this study, polyclonal yolk-immunoglobulin (IgY) antibodies purified from hEno1-immunized chickens showed a noticeable specific humoral response. Phage display technology was used to construct two antibody libraries of IgY gene-derived single-chain variable fragments (scFvs) containing 7.8 × 10⁷ and 5.4 × 10⁷ transformants, respectively. Phage-based ELISA indicated that specific anti-hEno1 clones were significantly enriched. The nucleotide sequences of scFv-expressing clones were determined and classified into seven groups either in the short linker or the long linker. Moreover, higher mutation rates were revealed in the CDR regions, especially in the CDR3. Three distinguish antigenic epitopes were identified on the hEno1 protein. The binding activities of selected anti-hEno1 scFv on hEno1-positive PE089 lung cancer cells were confirmed using Western blot, flow cytometry, and immunofluorescence assay. In particular, hEnS7 and hEnS8 scFv antibodies significantly suppressed the growth and migration of PE089 cells. Taken together, these chicken-derived anti-hEno1 IgY and scFv antibodies have great potential to develop diagnostic and therapeutic agents for the treatment of lung cancer patients with high expression levels of hEno1 protein.

Enolase 1, a Moonlighting Protein, as a Potential Target for Cancer Treatment

Enolase 1 (ENO1) is a moonlighting protein, function as a glycolysis enzyme, a plasminogen receptor and a DNA binding protein. ENO1 play an important role in the process of cancer development. The transcription, translation, post-translational modifying activities and the immunoregulatory role of ENO1 at the cancer development is receiving increasing attention. Some function model studies have shown that ENO1 is a potential target for cancer treatment. In this review, we provide a comprehensive overview of the characterization, function, related transduction cascades of ENO1 and its roles in the pathophysiology of cancers, which is a consequence of ENO1 signaling dysregulation. And the development of novels anticancer agents that targets ENO1 may provide a more attractive option for the treatment of cancers. The data of sarcoma and functional cancer models indicates that ENO1 may become a new potential target for anticancer therapy.

Integrated Bioinformatics Analysis of mRNAs and miRNAs Identified Potential Biomarkers of Oral Squamous Cell Carcinoma

Background: Oral cancer is a frequently encountered neoplasm of the head and neck region, being the eighth most common type of human malignancy worldwide. Despite improvement in its control, morbidity and mortality, rates have improved little in the past decades. The present investigations about gene interaction and pathways still could not clear the appearance and development of oral squamous cell carcinoma (OSCC), completely. The aim of this study is to investigate the key genes and microRNAs interaction in OSCC. Materials and Methods: The microarray datasets GSE13601 and GSE98463, including mRNA and miRNA profiles, were extracted from the GEO database and were analyzed using GEO2R. Functional and pathway enrichment analyses were performed by using the DAVID database. The protein-protein interaction (PPI) network was constructed and analyzed using STRING database and Cytoscape software, respectively. Finally, miRDB was applied to predict the targets of the differentially expressed miRNAs (DEMs). Results: Totally, 97 differentially expressed genes (DEGs) were found in OSCC, including 66 up-regulated and 31 down-regulated genes. The gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses showed that up-regulated genes were significantly enriched in movement of cell or subcellular component, cell adhesion, biological adhesion, cellular localization, apoptotic signaling pathway, while the downregulated genes were enriched in muscle system process and oxidation-reduction process. From the PPI network, the top 10 nodes with the highest degree were detected as hub genes. In addition, 18 DEMs were screened, which included 7 up-regulated and 11 down-regulated miRNAs. STAT1 was potentially targeted by three miRNAs, including has-miR- 6825-5P, has-miR-4495, and has-miR-5580-3P. Conclusion: The roles of DEMs such as hsa-mir-5580-3p in OSCC through interactions with DEGs CD44, ACLY, ACTR3, STAT1, LAMC2 and YWHAZ may offer a suitable candidate biomarker pattern for diagnosis, prognosis and treatment processes in OSCC.

ENO1 Overexpression in Pancreatic Cancer Patients and Its Clinical and Diagnostic Significance

We investigated in this study the expression of ENO1 in tissues and plasma of PDAC patients to evaluate its clinicopathological and diagnostic significance. ENO1 protein expression was detected in tissue microarray of human PDAC and adjacent noncancer tissues. Electrochemiluminescence immunoassay and amplified luminescent proximity homogeneous assay (AlphaLISA) were performed to measure CA19-9 and ENO1 concentration in plasma from PDAC patients and healthy controls. We demonstrated that ENO1 overexpression is positively correlated with clinical stage, lymph node metastasis, and poor prognosis of PDAC; ENO1 may function as a hopeful candidate diagnostic marker in combination with CA19-9 in PDAC diagnosis.

Downregulation of tumor suppressor MBP-1 by microRNA-363 in gastric carcinogenesis

Gastric carcinoma is one of the most common malignancies and the second most lethal cancer worldwide. The mechanisms underlying aggressiveness of gastric cancer still remain obscure. c-Myc promoter binding protein 1 (MBP-1) is a negative regulator of c-myc expression and ubiquitously expressed in normal human tissues. It is produced by alternative translation initiation of α-enolase gene. Both MBP-1 and α-enolase are involved in the control of tumorigenesis including gastric cancer. MicroRNAs (miRNAs) are involved in tumorigenesis and could have diagnostic, prognostic and therapeutic potential. In this study, whether miRNAs modulate tumorigenesis of gastric cancer cells through targeting MBP-1 was evaluated. We found that miR-363 targets 3'-untranslated region of human MBP-1/α-enolase messenger RNA. The exogenous miR-363 promotes growth, viability, progression, epithelial-mesenchymal transition and tumorsphere formation of SC-M1 gastric cancer cells through downregulation of MBP-1, whereas the knockdown of endogenous miR-363 suppresses tumorigenesis and progression of SC-M1 cells via upregulation of MBP-1. The miR-363/MBP-1 axis is also involved in the control of carcinogenesis in KATO III and SNU-16 gastric cancer cells. Furthermore, miR-363 induces the xenografted tumor growth and lung metastasis of SC-M1 cells through MBP-1 in vivo. Taken together, these results suggest that miR-363 plays an important role in the increment of gastric carcinogenesis via targeting MBP-1.

Three are better than one: plasminogen receptors as cancer theranostic targets

Activation of plasminogen on the cell surface initiates a cascade of protease activity with important implications for several physiological and pathological events. In particular, components of the plasminogen system participate in tumor growth, invasion and metastasis. Plasminogen receptors are in fact expressed on the cell surface of most tumors, and their expression frequently correlates with cancer diagnosis, survival and prognosis. Notably, they can trigger multiple specific immune responses in cancer patients, highlighting their role as tumor-associated antigens. In this review, three of the most characterized plasminogen receptors involved in tumorigenesis, namely Annexin 2 (ANX2), Cytokeratin 8 (CK8) and alpha-Enolase (ENOA), are analyzed to ascertain an overall view of their role in the most common cancers. This analysis emphasizes the possibility of delineating new personalized therapeutic strategies to counteract tumor growth and metastasis by targeting plasminogen receptors, as well as their potential application as cancer predictors.

Proteomic analysis of pancreatic intraepithelial neoplasia and pancreatic carcinoma in rat models

AIM

To detect the proteomic variabilities of pancreatic intraepithelial neoplasia (PanIN) and pancreatic carcinoma (PC) induced by 7,12-dimethylbenzanthracene (DMBA) in rat models and to identify potential biomarkers.

METHODS

Sixty adult male Sprague Dawley rats were randomized into three groups. The rats had DMBA implanted into their pancreas for one (n = 20) or two months (n = 20) or assigned to the normal group (n = 20). The rats were killed after one or two months, and were evaluated histopathologically. Three tissue samples from each group of rats with either normal pancreas, PanIN (PanIN-2) or PC were examined by 2D-DIGE. The different expression spot features were analyzed by matrix-assisted laser desorption/ionization-time of flight/time of flight (MALDI-TOF/TOF) tandem mass spectrometry. The expression of enolase 1, a differentially expressed protein, was identified by immunohistochemistry.

RESULTS

There was significant difference in the proportions of neoplastic changes between the 1- and 2-mogroups (P = 0.0488). There was an increase in the frequency of adenocarcinomas in the 2-mo group compared with the 1-mo group (P = 0.0309). No neoplastic changes were observed in any of the animals in the normal group. Enolase 1, pancreatic ELA3B, necdin, Hbp23, CHD3, hnRNP A2/B1, Rap80, and Gnb2l1 were up-regulated in the PanIN and PC tissues, and CEL, TPT1, NME2, PCK2, an unnamed protein product, and glycine C-acetyltransferase were down-regulated in the PanIN and PC tissues. The immunohistochemical results showed that enolase 1 expression was up-regulated in the pancreatic cancer tissues of rats and humans.

CONCLUSION

The pancreatic protein expression changes induced by DMBA suggest potential molecular targets for the early diagnosis and treatment of PC.

Myc promoter-binding protein-1 (MBP-1) is a novel potential prognostic marker in invasive ductal breast carcinoma

BACKGROUND

Alpha-enolase is a glycolytic enzyme that catalyses the formation of phosphoenolpyruvate in the cell cytoplasm. α-Enolase and the predominantly nuclear Myc promoter-binding protein-1 (MBP-1) originate from a single gene through the alternative use of translational starting sites. MBP-1 binds to the P2 c-myc promoter and competes with TATA-box binding protein (TBP) to suppress gene transcription. Although several studies have shown an antiproliferative effect of MBP-1 overexpression on several human cancer cells, to date detailed observations of α-enolase and MBP-1 relative expression in primary tumors versus normal tissues and their correlation with clinicopathological features have not been undertaken.

METHODOLOGY AND FINDINGS

We analyzed α-enolase and MBP-1 expression in normal breast epithelium and primary invasive ductal breast carcinoma (IDC) from 177 patients by Western blot and immunohistochemical analyses, using highly specific anti-α-enolase monoclonal antibodies. A significant increase in the expression of cytoplasmic α-enolase was observed in 98% of the tumors analysed, compared to normal tissues. Nuclear MBP-1 was found in almost all the normal tissues while its expression was retained in only 35% of the tumors. Statistically significant associations were observed among the nuclear expression of MBP-1 and ErbB2 status, Ki-67 expression, node status and tumor grade. Furthermore MBP-1 expression was associated with good survival of patients with IDC.

CONCLUSIONS

MBP-1 functions in repressing c-myc gene expression and the results presented indicate that the loss of nuclear MBP-1 expression in a large number of IDC may be a critical step in the development and progression of breast cancer and a predictor of adverse outcome. Nuclear MBP-1 appears to be a novel and valuable histochemical marker with potential prognostic value in breast cancer.

Generation and characterization of anti-alpha-enolase single-chain antibodies in chicken

It was previously reported that up-regulation of α-enolase protein was detected in 65% of patients with non-small cell lung cancers (NSCLC). Moreover, a high titer of anti-α-enolase antibodies was developed in a smaller proportion (7.4%) of these patients than in non-tumor-associated patients and healthy subjects. In the present study, we characterized polyclonal and single-chain variable fragment (scFv) anti-α-enolase antibodies from immunized chickens. The E. coli-derived recombinant α-enolase protein was purified to its high homogenicity as verified by SDS-PAGE. After the 4th immunization, a high titer of specific polyclonal anti-α-enolase antibodies was elicited in immunized chickens and specifically recognized the purified human α-enolase antigen as determined by Western blot and ELISA. The expressed heavy and light chain variable genes (VH and VL) were isolated from spleen B cells and amplified to construct phage antibody libraries containing scFv molecules. After four rounds of panning selection, the scFv antibodies of randomly chosen clones were expressed and their binding specificity to α-enolase protein was verified using competitive ELISA, flow cytometry and immunofluorescence staining. Nucleotide sequence analysis from 10 α-enolase binding clones showed that 3 (30%) clones used identical heavy and light genes for scFv antibody expression, as represented by EnL5. Notably, amino acid changes in complementarity-determining regions (CDRs) were more frequently observed than those in framework regions (FRs) in all clones, indicating a strong affinity selection through mutations. All together, it is believed that these polyclonal and scFv IgY antibodies may be helpful in the development of molecular diagnostic and therapeutic agents for lung cancers in the future.

ENO1, a potential prognostic head and neck cancer marker, promotes transformation partly via chemokine CCL20 induction

The success of using glycolytic inhibitors for cancer treatment depends on studying the individual role of frequently deregulated glycolytic genes in cancer. This report aims to study the prognostic implication, and determine the cellular role and action mechanism of glycolytic ENO1 overexpression in head and neck cancer. The relationship of ENO1 mRNA expression in 44-pair clinical specimens with patient clinicopathologic characteristics was analysed by semi-quantitative RT-PCR, Kaplan-Meier survival curve and Cox model analyses. Following ectopic ENO1 expression or knockdown, we studied the proliferative, migratory, invasive, colony-forming and tumourigenic abilities of ENO1-genetically altered cells. DNA microarray analysis was used to identify downstream targets responsible for the ENO1 action in the cells. The expression of ENO1 mRNA was increased in 68% of tumour (T) specimens when compared to their normal (N) counterparts, and positively associated with clinical progression (p<0.05). High ENO1 expression (T/N2) was frequently observed in the patients with large primary tumours, late clinical stages or advanced neck metastasis. Moreover, high ENO1 patients had significantly poorer clinical outcomes than low expressers (T/N<2). Ectopic ENO1 expression stimulated cell transformation, invasion and tongue tumour formation. ENO1 knockdown abrogated the stimulation. Suppression of ENO1-induced proinflammatory CCL20 chemokine expression significantly attenuated its stimulatory effects on cell transformation and invasion. A concordant expression of ENO1 and CCL20 was validated both in ENO1-expressing cells and in clinical specimens. Together, we demonstrate a prognostic role of ENO1 overexpression in head and neck cancer and ENO1-mediated promotion of cell transformation and invasion partly via induced CCL20 expression.

MBP-1 suppresses growth and metastasis of gastric cancer cells through COX-2

The c-Myc promoter binding protein 1 (MBP-1) is a transcriptional suppressor of c-myc expression and involved in control of tumorigenesis. Gastric cancer is one of the most frequent neoplasms and lethal malignancies worldwide. So far, the regulatory mechanism of its aggressiveness has not been clearly characterized. Here we studied roles of MBP-1 in gastric cancer progression. We found that cell proliferation was inhibited by MBP-1 overexpression in human stomach adenocarcinoma SC-M1 cells. Colony formation, migration, and invasion abilities of SC-M1 cells were suppressed by MBP-1 overexpression but promoted by MBP-1 knockdown. Furthermore, the xenografted tumor growth of SC-M1 cells was suppressed by MBP-1 overexpression. Metastasis in lungs of mice was inhibited by MBP-1 after tail vein injection with SC-M1 cells. MBP-1 also suppressed epithelial-mesenchymal transition in SC-M1 cells. Additionally, MBP-1 bound on cyclooxygenase 2 (COX-2) promoter and downregulated COX-2 expression. The MBP-1-suppressed tumor progression in SC-M1 cells were through inhibition of COX-2 expression. MBP-1 also exerted a suppressive effect on tumor progression of other gastric cancer cells such as AGS and NUGC-3 cells. Taken together, these results suggest that MBP-1-suppressed COX-2 expression plays an important role in the inhibition of growth and progression of gastric cancer.

Generally detected proteins in comparative proteomics--a matter of cellular stress response?

The specificity of proteins identified by proteomics as biomarkers for defined conditions or as components of biological processes and pathways is crucial. We critically reviewed differentially expressed proteins from comparative proteomic studies identified by 2-DE followed by MS, especially with MALDI technique. Based on 66 of those studies, a list of 44 proteins is presented as generally detected proteins regardless of species, in vivo or in vitro conditions, tissues and organs, and experimental objective. Similarly, a list of 28 generally detected protein families is presented. The enriched functions linked to these generally detected proteins reveal that there are some common biological features beyond the technical limitations. Cellular stress response can be the universal reason as to why these proteins are generally expressed differentially. Using those proteins as biomarkers for cellular processes other than stress response should be done with caution. In future proteomic studies more profound approaches should be applied to look beyond these proteins to find specific biomarkers. Our results are discussed in relation to a recent viewpoint publication by Petrak et al. [Proteomics 2008, 8, 1744-1749].

Differential expression of alpha-enolase in the normal and pathological cardiac growth

OBJECTIVES

It was found that alpha-enolase was dramatically up-regulated in the hypertrophic hearts of SHR in our previous study. The purposes of this study were to examine the expression pattern of alpha-enolase in pre- and postnatal myocardium of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats, and to explore the relationship between the overexpression of alpha-enolase and left ventricular hypertrophy.

METHODS

HE staining was used for the measurement of cardiac hypertrophy. Immunohistochemical technique was used to evaluate the location of alpha-enolase. The expressions of alpha-enolase in the left cardiac ventricles at different development times were examined by Real-time RT-PCR and Western blot.

RESULTS

Cardiac hypertrophy was found in SHR rats at 4 weeks of age and remained up to 24 weeks of age. The signals of alpha-enolase protein were strong and existed extensively in hypertrophic myocardium in SHR, while in the normal myocardium of WKY, the signals were scarcely found and weak. The levels of alpha-enolase mRNA and protein in SHR and WKY hearts during fetal stage and newborn stage were similar, while from 4 weeks of age to 24 weeks of age, accompanied by the cardiac hypertrophy, the levels of alpha-enolase mRNA and protein in left ventricle of SHR were significantly higher than that in WKY.

CONCLUSIONS

The expressions of alpha-enolase in the left ventricle of the rats during normal and pathological cardiac development were different. This phenomenon provides the potential clues to understanding pathophysiological mechanisms in cardiac hypertrophy of SHR.

Identification of differential HLA-binding peptide between two hepatoma cell lines HepG2 and HepG2.2.15

AIM: To screen the differential HLA-binding peptides between HepG2 and HepG2.2.15 cell lines, and to find some HLA-binding peptides correlated with hepatitis B virus (HBV) infection.

METHODS: HepG2 and HepG2.2.15 cells were harvested (108 cells), and the peptides were isolated from the cell membrane by mild acid elution, respectively. Then the mixture of peptides was fractionated by high performance liquid chromatography (HPLC) and the differential fractions only expressed in HepG2.2.15 cell line were identified by nanoESI-MS/MS analysis. Bioinformatic analysis and MASCOT index were used to investigate the sequence and source of the peptides. Finally the expression of mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: HPLC fractions were markedly different between HepG2 and HepG2.2.15 cells. A peptide, SPDDPSRYISPDQ, from enolase 1 (ENO1) was obtained, which was only expressed in HepG2.2.15 cells, by nanoESI-MS/MS analysis. The result of RT-PCR confirmed that ENO1 expression was significantly higher in HepG2.2.15 cells than that in HepG2 cells.

CONCLUSION: A human peptide SPDDPSRYISPDQ from ENO1 can be presented on the surface of HepG2.2.15 cells by HLA, and ENO1 mRNA expression is significantly higher in HepG2.2.15 than that in HepG2, suggesting that HBV infection may cause the up-regualtion of ENO1 expression.

The activated Notch1 receptor cooperates with alpha-enolase and MBP-1 in modulating c-myc activity

The Notch signal pathway plays multifaceted roles to promote or suppress tumorigenesis. The Notch1 receptor intracellular domain (N1IC), the activated form of the Notch1 receptor, activates the c-myc proto-oncogene. The complex of N1IC and transcription factor YY1 binds to the human c-myc promoter to enhance c-myc expression in a CBF1-independent manner. Here we demonstrated that N1IC interacted with the c-Myc-regulating proteins alpha-enolase and c-myc promoter binding protein 1 (MBP-1). Both alpha-enolase and MBP-1 suppressed the N1IC-enhanced activity of the c-myc promoter in a CBF1-independent manner. The YY1 response element in front of the P2 c-myc promoter was essential and sufficient for the modulation of c-myc by N1IC and alpha-enolase or MBP-1. Furthermore, N1IC, YY1, and alpha-enolase or MBP-1 but not CBF1 bound to the c-myc promoter through associating with the YY1 response element. Hemin-induced erythroid differentiation was suppressed by N1IC in K562 cells. This suppression was relieved by the expression of alpha-enolase and MBP-1. In addition, both alpha-enolase and MBP-1 suppressed the N1IC-enhanced colony-forming ability through c-myc. These results indicate that the activated Notch1 receptor and alpha-enolase or MBP-1 cooperate in controlling c-myc expression through binding the YY1 response element of the c-myc promoter to regulate tumorigenesis.

Involvement of Wnt4 signaling during myogenic proliferation and differentiation of skeletal muscle

The direct effects of Wnt4 on myogenic proliferation and differentiation of skeletal muscle precursors are examined. Wnt4 cDNA was misexpressed in the presumptive limb fields on the right side of stage 16 chick embryos. Muscle development was evaluated at stage 37 with hematoxylin-eosin staining and immunohistochemical staining for fast and slow types of the myosin heavy chain (MyHC). Overexpression of Wnt4 resulted in up-regulation of Pax7 and MyoD1 expression. The muscle mass showed a significant increase compared with that of the control limb. The area for fast MyHC-expressing cells showed a significant increase, whereas a slight decrease was observed for slow MyHC-expressing cells. Wnt4 acted as a stimulator during myogenic proliferation and differentiation, especially, for fast-type muscle in C2C12 cells. The present results are identical to those of myostatin knockout, suggesting that Wnt4 is acting against myostatin as an antagonizing signal for myostatin.