High Expression of ENO1 and Low Levels of Circulating Anti-ENO1 Autoantibodies in Patients with Myelodysplastic Neoplasms and Acute Myeloid Leukaemia

In solid tumours, high expression of the glycolytic enzyme, α-enolase (ENO1), predicts for poor patient overall survival (OS), and circulating autoantibodies to ENO1 correlate positively with diagnosis and negatively with advanced disease. Although ENO1 is one of the most highly expressed genes in acute myeloid leukaemia (AML), its potential role as a biomarker in AML or its precursor, myelodysplastic neoplasms (MDS), has not been investigated. A meta-analysis of nine AML online datasets (n = 1419 patients) revealed that high ENO1 expression predicts for poor OS (HR = 1.22, 95% CI: 1.10-1.34, p < 0.001). Additionally, when compared to AML in remission (n = 5), ENO1 protein detected by immunohistochemistry was significantly higher at diagnosis in bone marrow from both AML (n = 5, p < 0.01) and MDS patients (n = 12, p < 0.05), and did not correlate with percentage of blasts (r = 0.28, p = 0.21). AML patients (n = 34) had lower circulating levels of ENO1 autoantibodies detected by ELISA compared to 26 MDS and 18 controls (p = 0.003). However, there was no difference in OS between AML patients with high vs. low levels of anti-ENO1 autoantibodies (p = 0.77). BM immunostaining for ENO1 and patient monitoring of anti-ENO1 autoantibody levels may be useful biomarkers for MDS and AML.

The use of intravenous immunoglobulin in the treatment of Hashimoto's encephalopathy: case based review

Background

Hashimoto's encephalopathy (HE) is a controversial immunological neuropsychiatric disease, with a poorly understood pathogenesis. It is characterized by symptoms of acute or subacute encephalopathy which usually occur in the presence of elevated levels of antithyroid antibodies. Even though it is also known as steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT), some cases appear to be steroid-resistant. This review examined whether treatment of Hashimoto's encephalopathy with intravenous immunoglobulin (IVIG) is associated with better clinical outcomes than the standard therapy. Additionally, we presented a case of a 59-year-old man who presented with severe neurological manifestations and was successfully treated with intravenous immunoglobulin.

Methods

The online databases PubMed and EMBASE were searched.

Results

A total of 1,365 articles were identified. After the deletion of 112 duplicates, 1,253 studies were screened by evaluating the title and abstract, focusing on Hashimoto's encephalopathy cases where IVIG were used. 846 studies were excluded because they were not relevant to the topic or included pediatric population. Therefore, 407 full-text articles were assessed for eligibility. The final analysis included 14 eligible articles after 393 were excluded (irrelevant texts, not written in English, full-text not available). In the majority of the selected case-reports, IVIG was associated with a good outcome, sometimes even with dramatic improvements in patient's status.

Conclusion

In last years, intravenous immunoglobulin therapy proved its utility in Hashimoto's encephalopathy's treatment, being a well tolerated therapy associated with remarkable improvement in patient's status. Further research is still needed in order to define the optimal treatment protocol for Hashimoto's encephalopathy and to establish if intravenous immunoglobulin can also be used as a first-line therapy, alone or in combination with steroids.

ENO1 Promotes OSCC Migration and Invasion by Orchestrating IL-6 Secretion from Macrophages via a Positive Feedback Loop

Oral squamous cell carcinoma (OSCC) has a five-year survival rate of less than 50% due to its susceptibility to invasion and metastasis. Crosstalk between tumor cells and macrophages has been proven to play a critical role in tumor cell migration and invasion. However, the specific mechanisms by which tumor cells interact with macrophages have not been fully elucidated. This study sought to investigate the regulatory mechanism of tumor cell-derived alpha-enolase (ENO1) in the interaction between tumor cells and macrophages during OSCC progression. Small interfering RNA (siRNA) transfection and recombinant human ENO1 (rhENO1) stimulation were used to interfere with the interaction between tumor cells and macrophages. Our results showed that ENO1 was expressed higher in CAL27 cells than in HaCaT cells and regulated lactic acid release in CAL27 cells. Conditioned medium of macrophages (Macro-CM) significantly up-regulated the ENO1 mRNA expression and protein secretion in CAL27 cells. ENO1 promoted the migration and invasion of tumor cells by facilitating the epithelial-mesenchymal transition (EMT) through macrophages. ENO1 orchestrated the IL-6 secretion of macrophages via tumor cell-derived lactic acid and the paracrine ENO1/Toll-like receptor (TLR4) signaling pathway. In turn, IL-6 promoted the migration and invasion of tumor cells. Collectively, ENO1 promotes tumor cell migration and invasion by orchestrating IL-6 secretion of macrophages via a dual mechanism, thus forming a positive feedback loop to promote OSCC progression. ENO1 might be a promising therapeutic target which is expected to control OSCC progression.

Proteomic and metabonomic analysis uncovering Enterovirus A71 reprogramming host cell metabolic pathway

Enterovirus A71 (EV71) infection can cause hand, foot, and mouth disease (HFMD) and severe neurological complications in children. However, the biological processes regulated by EV71 remain poorly understood. Herein, proteomics and metabonomics studies were conducted to uncover the mechanism of EV71 infection in rhabdomyosarcoma (RD) cells and identify potential drug targets. Differential expressed proteins from enriched membrane were analyzed by isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics technology. Twenty-six differential proteins with 1.5-fold (p < 0.05) change were detected, including 14 upregulated proteins and 12 downregulated proteins. The upregulated proteins are mainly involved in metabolic process, especially in the glycolysis pathway. Alpha-enolase (ENO1) protein was found to increase with temporal dependence following EV71 infection. The targeted metabolomics analysis revealed that glucose absorption and glycolysis metabolites were increased after EV71 infection. The glycolysis pathway was inhibited by knocking down ENO1 or the use of a glycolysis inhibitor (dichloroacetic acid [DCA]); and we found that EV71 infection was inhibited by depleting ENO1 or using DCA. Our study indicates that EV71 may reprogram glucose metabolism by activating glycolysis, and EV71 infection can be inhibited by interrupting the glycolysis pathway. ENO1 may be a potential target against EV71, and DCA could act as an inhibitor of EV71.

Mycoplasma suis Alpha-Enolase Subunit Vaccine Induces an Immune Response in Experimental Animals

Recombinant protein technology has emerged as an excellent option for vaccine development. However, prior to our study, the immune induction ability of recombinant Mycoplasma suis alpha-enolase (rMseno) in animals remained unclear. The purpose of this study was to develop a rMseno protein subunit vaccine and to determine its ability to elicit an immunological response. To accomplish this, we cloned the gene into pET-15b, expressed it in BL21 cells, and purified it. Following the establishment of immunity, the immunogenicity and potential for protection of rMseno were evaluated in mice and piglets. The results demonstrate that anti-M. suis serum recognized the pure rMseno protein in both mice and piglets as evidenced by high levels of specific anti-rMseno antibodies, significantly increased levels of IFN-γ and IL-4 cytokines, and significantly increased T lymphocyte proliferation index. Piglets also had significantly increased levels of specific IgG₁, IgG_2a, CD4⁺, and CD8⁺ cells. The rMseno findings demonstrated a robust immunological response in mice and piglets, affording partial clinical protective efficacy in piglets.

Alpha-Enolase: Emerging Tumor-Associated Antigen, Cancer Biomarker, and Oncotherapeutic Target

Alpha-enolase, also known as enolase-1 (ENO1), is a glycolytic enzyme that “moonlights” as a plasminogen receptor in the cell surface, particularly in tumors, contributing to cancer cell proliferation, migration, invasion, and metastasis. ENO1 also promotes other oncogenic events, including protein-protein interactions that regulate glycolysis, activation of signaling pathways, and resistance to chemotherapy. ENO1 overexpression has been established in a broad range of human cancers and is often associated with poor prognosis. This increased expression is usually accompanied by the generation of anti-ENO1 autoantibodies in some cancer patients, making this protein a tumor associated antigen. These autoantibodies are common in patients with cancer associated retinopathy, where they exert pathogenic effects, and may be triggered by immunodominant peptides within the ENO1 sequence or by posttranslational modifications. ENO1 overexpression in multiple cancer types, localization in the tumor cell surface, and demonstrated targetability make this protein a promising cancer biomarker and therapeutic target. This mini-review summarizes our current knowledge of ENO1 functions in cancer and its growing potential as a cancer biomarker and guide for the development of novel anti-tumor treatments.

Nell-1-ΔE, a novel transcript of Nell-1, inhibits cell migration by interacting with enolase-1

NELL-1 is a secreted protein that was originally found to be upregulated in pathologically fusing and fused sutures in non-syndromic unilateral coronal synostosis patients. Apart from the ability of NELL-1 to promote osteogenesis in long and craniofacial bones, NELL-1 reportedly inhibits the formation of several benign and malignant tumors. We previously identified a novel transcript of Nell-1 that lacked a calcium-binding epidermal growth factor (EGF)-like domain compared with full-length Nell-1; this new transcript was named Nell-1-ΔE. Three obvious structural differences between these two isoforms were revealed by homology modeling. Furthermore, the recombinant Nell-1-ΔE protein, but not the full-length Nell-1 protein, inhibited cell migration in vitro. However, full-length Nell-1 and Nell-1-ΔE proteins were present in similar subcellular locations and displayed similar expression patterns in both the intracellular and extracellular spaces. The results from the co-immunoprecipitation and liquid chromatography/tandem mass spectrometry analyses using two cell lines demonstrated that Nell-1-ΔE but not full-length Nell-1 interacted with enolase-1 in the extracellular spaces of both cell lines. The results of wound healing assays using ENO-1-overexpressing cells treated with full-length Nell-1/Nell-1-ΔE suggested that Nell-1-ΔE inhibited cell migration by interacting with ENO-1. Our study indicated that the novel transcript Nell-1-ΔE, but not full-length Nell-1, might be a candidate tumor suppressor factor for basic research and clinical practice.

Humoral immune responses toward tumor-derived antigens in previously untreated patients with chronic lymphocytic leukemia

In chronic lymphocytic leukemia (CLL) the occurrence and the impact of antibody responses toward tumor-derived antigens are largely unexplored. Our serological proteomic data show that antibodies toward 47 identified antigens are detectable in 29 out of 35 patients (83%) with untreated CLL. The glycolytic enzyme alpha-enolase (ENO1) is the most frequently recognized antigen (i.e. 54% of CLL sera). We show that ENO1 is upregulated in the proliferating B-cell fraction of CLL lymph nodes. In CLL cells of the peripheral blood, ENO1 is exclusively expressed at the intracellular level, whereas it is exposed on the surface of apoptotic leukemic cells.

From the clinical standpoint, patients with progressive CLL show a higher number of antigen recognitions compared to patients with stable disease. Consistently, the anti-ENO1 antibodies are prevalent in sera from patients with progressive disease and their presence is predictive of a shorter time to first treatment. This clinical inefficacy associates with the inability of patients’ sera to trigger complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity against leukemic cells.

Together, these results indicate that antibody responses toward tumor-derived antigens are frequently detectable in sera from patients with CLL, but they are expression of a disrupted immune system and unable to hamper disease progression.

Investigation of three potential autoantibodies in Sjogren's syndrome and associated MALT lymphoma

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease which might progress to mucosal-associated lymphoid tissue lymphoma (pSS/MALT). Diagnosis of pSS requires an invasive tissue biopsy and a delay in diagnosis of pSS has been frequently reported. In this study, four proteins including cofilin-1, alpha-enolase, annexin A2 and Rho GDP-dissociation inhibitor 2 (RGI2) were found to be over-expressed in pSS and pSS/MALT by 2D gel electrophoresis/mass spectrometry, and the finding was verified by the microarray analysis and western blotting results. We then developed enzyme-linked immunosorbent assays for autoantibodies including anti-cofilin-1, anti-alpha-enolase and anti-RGI2 with good quantitative ability. The expression levels of salivary anti-cofilin-1, anti-alpha-enolase and anti-RGI2 were found to be the highest in pSS/MALT patients and lowest in healthy controls. The combination of these three antiantibodies yielded an “area under the curve” (AUC) value of 0.94 with an 86% sensitivity and 93% specificity in distinguishing patients with pSS from healthy controls, an AUC value of 0.99 with a 95% sensitivity and 94% specificity in distinguishing patients with pSS/MALT from healthy controls and an AUC value of 0.86 with a 75% sensitivity and 94% specificity in distinguishing pSS/MALT patients from pSS patients. Collectively, we have successfully identified a panel of potential autoantigens that are progressively up-regulated during the development of pSS and its progression to MALT lymphoma. The autoantibody biomarkers may be used to help diagnose pSS and predict its progression to MALT lymphoma.

Alpha-enolase regulates hepatitis B virus replication through suppression of the interferon signalling pathway

Persistent chronic infection with hepatitis B virus (HBV) is a major risk factor for the development of HBV-related diseases. The molecular mechanisms that underlie HBV infection and associated carcinogenesis are not fully understood. The aim of this study was to explore the role of ENO1 in HBV replication processes. Here, we examined ENO1 expression levels in HBV-infected and non-HBV-infected liver tissues and cells by Western blot analysis, real-time PCR and immunohistochemistry. In addition, HBsAg and HBeAg in the media of transfected HepG2.2.15 cells were detected using an electrochemical luminescence analyser within 48 hours after ENO1-specific siRNA transfection. The expression levels of HBV DNA, type I interferon and 5 downstream IFN-stimulated genes in HepG2.2.15 cells were examined using real-time PCR. We found ENO1 expression was upregulated in the HBV-infected liver tissues and cells. Silencing of ENO1 resulted in a significant reduction in HBV replication, and this siRNA-mediated reaction also caused the upregulation of expression of type I interferon and downstream IFN-stimulated genes. Therefore, we come to the conclusion ENO1 is involved in HBV replication. It is therefore likely that HBV replication is enhanced following suppression of the IFN signalling pathway. However, the mechanisms that underpin ENO1-mediated modulation of the IFN signalling pathway remain to be elucidated.

Next Generation Immunotherapy for Pancreatic Cancer: DNA Vaccination is Seeking New Combo Partners. Cancers (Basel). 2018;10. [PMID: 29462900 PMCID: PMC5836083 DOI: 10.3390/cancers10020051]

Pancreatic Ductal Adenocarcinoma (PDA) is an almost incurable radio- and chemo-resistant tumor, and its microenvironment is characterized by a strong desmoplastic reaction associated with a significant infiltration of T regulatory lymphocytes and myeloid-derived suppressor cells (Tregs, MDSC). Investigating immunological targets has identified a number of metabolic and cytoskeletal related molecules, which are typically recognized by circulating antibodies. Among these molecules we have investigated alpha-enolase (ENO1), a glycolytic enzyme that also acts a plasminogen receptor. ENO1 is also recognized by T cells in PDA patients, so we developed a DNA vaccine that targets ENO1. This efficiently induces many immunological processes (antibody formation and complement-dependent cytotoxicity (CDC)-mediated tumor killing, infiltration of effector T cells, reduction of infiltration of myeloid and Treg suppressor cells), which significantly increase the survival of genetically engineered mice that spontaneously develop pancreatic cancer. Although promising, the ENO1 DNA vaccine does not completely eradicate the tumor, which, after an initial growth inhibition, returns to proliferate again, especially when Tregs and MDSC ensue in the tumor mass. This led us to develop possible strategies for combinatorial treatments aimed to broaden and sustain the antitumor immune response elicited by DNA vaccination. Based on the data we have obtained in recent years, this review will discuss the biological bases of possible combinatorial treatments (chemotherapy, PI3K inhibitors, tumor-associated macrophages, ENO1 inhibitors) that could be effective in amplifying the response induced by the immune vaccination in PDA.

Rh2E2, a novel metabolic suppressor, specifically inhibits energy-based metabolism of tumor cells

Energy metabolism in cancer cells is often increased to meet their higher proliferative rate and biosynthesis demands. Suppressing cancer cell metabolism using agents like metformin has become an attractive strategy for treating cancer patients. We showed that a novel ginsenoside derivative, Rh2E2, is as effective as aspirin in preventing the development of AOM/DSS-induced colorectal cancer and suppresses tumor growth and metastasis in a LLC-1 xenograft. A sub-chronic and acute toxicity LD₅₀ test of Rh2E2 showed no harmful reactions at the maximum oral dosage of 5000 mg/kg body weight in mice. Proteomic profiling revealed that Rh2E2 specifically inhibited ATP production in cancer cells via down-regulation of metabolic enzymes involving glycolysis, fatty acid β-oxidation and the tricarboxylic acid cycle, leading to specific cytotoxicity and S-phase cell cycle arrest in cancer cells. Those findings suggest that Rh2E2 possesses a novel and safe anti-metabolic agent for cancer patients by specific reduction of energy-based metabolism in cancer cells.

Targeting the Warburg effect in cancer cells through ENO1 knockdown rescues oxidative phosphorylation and induces growth arrest

In the last 5 years, novel knowledge on tumor metabolism has been revealed with the identification of critical factors that fuel tumors. Alpha-enolase (ENO1) is commonly over-expressed in tumors and is a clinically relevant candidate molecular target for immunotherapy. Here, we silenced ENO1 in human cancer cell lines and evaluated its impact through proteomic, biochemical and functional approaches. ENO1 silencing increased reactive oxygen species that were mainly generated through the sorbitol and NADPH oxidase pathways, as well as autophagy and catabolic pathway adaptations, which together affect cancer cell growth and induce senescence. These findings represent the first comprehensive metabolic analysis following ENO1 silencing. Inhibition of ENO1, either alone, or in combination with other pathways which were perturbed by ENO1 silencing, opens novel avenues for future therapeutic approaches.

A T4SS Effector Targets Host Cell Alpha-Enolase Contributing to Brucella abortus Intracellular Lifestyle

Brucella abortus, the causative agent of bovine brucellosis, invades and replicates within cells inside a membrane-bound compartment known as the Brucella containing vacuole (BCV). After trafficking along the endocytic and secretory pathways, BCVs mature into endoplasmic reticulum-derived compartments permissive for bacterial replication. Brucella Type IV Secretion System (VirB) is a major virulence factor essential for the biogenesis of the replicative organelle. Upon infection, Brucella uses the VirB system to translocate effector proteins from the BCV into the host cell cytoplasm. Although the functions of many translocated proteins remain unknown, some of them have been demonstrated to modulate host cell signaling pathways to favor intracellular survival and replication. BPE123 (BAB2_0123) is a B. abortus VirB-translocated effector protein recently identified by our group whose function is yet unknown. In an attempt to identify host cell proteins interacting with BPE123, a pull-down assay was performed and human alpha-enolase (ENO-1) was identified by LC/MS-MS as a potential interaction partner of BPE123. These results were confirmed by immunoprecipitation assays. In bone-marrow derived macrophages infected with B. abortus, ENO-1 associates to BCVs in a BPE123-dependent manner, indicating that interaction with translocated BPE123 is also occurring during the intracellular phase of the bacterium. Furthermore, ENO-1 depletion by siRNA impaired B. abortus intracellular replication in HeLa cells, confirming a role for α-enolase during the infection process. Indeed, ENO-1 activity levels were enhanced upon B. abortus infection of THP-1 macrophagic cells, and this activation is highly dependent on BPE123. Taken together, these results suggest that interaction between BPE123 and host cell ENO-1 contributes to the intracellular lifestyle of B. abortus.