Dysregulated Gab1 signalling in triple negative breast cancer.

BACKGROUND: Breast cancer is the most common cancer in women worldwide. Triple-negative breast cancer (TNBC) is especially aggressive and associated with high metastasis. The aetiology of TNBC is heterogeneous and characterised by multiple different mutations that amongst others cause constitutive and dysregulated MAPK and PI3K signalling. Additionally, in more than 50% of TNBC patients, the epidermal growth factor receptor (EGFR) is overexpressed and constitutively active. The multi-site docking protein Grb2-associated binder 1 (Gab1) is a central signalling hub that connects MAPK and PI3K signalling. METHODS: Expression and activation of members of the Gab1/PI3K/MAPK signalling network were assessed in cells from different breast cancer subtypes. Influence of short- and long-term inhibition of EGFR, MAPK and PI3K on the activation of the Gab1/PI3K/MAPK signalling network as well as on cell viability, proliferation and migration was determined. Additionally, cellular localisation of Gab1 and Gab1 variants in naive cells and cells treated with the above-mentioned inhibitors was investigated. RESULTS: We show that, activation of the Gab1/PI3K/MAPK signalling network is heterogeneous between different breast cancer subtypes. Gab1 phosphorylation and plasma membrane recruitment of Gab1 are dysregulated in the EGFRhigh TNBC cell line MDA-MB-468. While the Gab1/MAPK/PI3K signalling network follows canonical Gab1 signalling in naive MDA-MB-468 cells, Gab1 signalling is changed in cells that acquired resistance towards MAPK and PI3K inhibition. In resistant cells, Gab1 is not located at the plasma membrane despite strong activation of PI3K and MAPK. Furthermore, Gab1 tyrosine phosphorylation is uncoupled from plasma membrane recruitment. CONCLUSION: Our study indicates that Gab1 signalling changes fundamentally during the acquisition of resistance to pharmacological inhibitors. Given the molecular heterogeneity between breast cancer subtypes, the detailed understanding of dysregulated and aberrant signalling is an absolute necessity in order to develop personalised therapies for patients with TNBC.

Breast cancer is very diverse among different patients. Understanding these differences is important for specific and successful treatment of breast cancer patients. About 15% of breast cancer patients have a very severe form of breast cancer called triple negative breast cancer. So far, no specific treatment for these patients exists. Triple-negative breast cancer cells divide without external stimuli as intracellular signalling is constitutively activated in these cells. We show that, in a specific type of triple negative breast cancer, an intracellular signalling network called Gab1/MAPK/PI3K signalling is disturbed. In these breast cancer cells, the Gab1/MAPK/PI3K network is initiated by hyperactive epidermal growth factor receptor (EGFR). In naive untreated breast cancer cells, the EGFR-induced Gab1/MAPK/PI3K network follows the rules described for healthy cells. However, when the cells acquire resistance to pharmacological inhibition of this network, substantial changes in this network happen. This study is the first showing that Gab1 signalling fundamentally changes during resistance development. Understanding the underlying molecular changes during cancer progression is fundamental for future development of personalised therapies for patients with triple negative breast cancer.

Inhibition of EIF2α Dephosphorylation Decreases Cell Viability and Synergizes with Standard-of-Care Chemotherapeutics in Head and Neck Squamous Cell Carcinoma.

Drug resistance is a common cause of therapy failure in head and neck squamous cell carcinoma (HNSCC). One approach to tackling it is by targeting fundamental cellular processes, such as translation. The eukaryotic translation initiation factor 2α (EIF2α) is a key player in canonical translation initiation and integrates diverse stress signals; when phosphorylated, it curbs global protein synthesis. This study evaluates EIF2α expression and phosphorylation in HNSCC. A small-molecule inhibitor of EIF2α dephosphorylation, salubrinal, was tested in vitro, followed by viability assays, flow cytometry, and immunoblot analyses. Patient-derived 3D tumor spheres (PD3DS) were cultured with salubrinal and their viability assessed. Lastly, salubrinal was evaluated with standard-of-care chemotherapeutics. Our analysis of RNA and proteomics data shows elevated EIF2α expression in HNSCC. Immunohistochemical staining reveals increasing EIF2α abundance from premalignant lesions to invasive and metastatic carcinoma. In immunoblots from intraoperative samples, EIF2α expression and steady-state phosphorylation are higher in HNSCC than in neighboring normal tissue. Inhibition of EIF2α dephosphorylation decreases HNSCC cell viability and clonogenic survival and impairs the G1/S transition. Salubrinal also decreases the viability of PD3DS and acts synergistically with cisplatin, 5-fluorouracil, bleomycin, and proteasome inhibitors. Our results indicate that pharmacological inhibition of EIF2α dephosphorylation is a potential therapeutic strategy for HNSCC.

Expression of Eukaryotic Translation Initiation Factors in the Urothelial Carcinoma of the Bladder.

BACKGROUND/AIM: Urothelial carcinoma (UC) of the urinary bladder is the second most common tumor in the field of urology and is characterized by a relatively aggressive growth behavior. New therapeutic approaches are required to improve the prognosis of affected patients. We hypothesized a link between dysregulation of eIFs and the development of UC. Therefore, in the present work, we investigated the expression behavior of eIF1, eIF1AY, eIF1AX, eIF2α, eIF3a, eIF3b, eIF4B, eIF4E, eIF4G, eIF5A, eIF5B, and eIF6 in UC compared with that in urothelial tissue. MATERIALS AND METHODS: Paraffin-embedded tumor tissue samples from 107 patients suffering from UC were examined. Seventy-six patients contained adjacent urothelial tissue. Three tumor tissue cylinders (tumor collective) and two urothelial tissue cylinders (control collective) were collected per patient and embedded in tissue microarray (TMA) blocks. Immunohistochemical staining of the TMA sections was then performed. The staining results were assessed semi-quantitatively. Staining intensities and immunoreactive scores (IRS) of both collectives were compared. In each case, a distinction was made between cytoplasmic and nuclear staining. RESULTS: Significant up-regulation of eIF1AY, eIF2α, eIF3a, eIF3b, eIF4B, eIF4G, eIF5B, and eIF6 was found in the cytoplasm of UC. In contrast, eIF1 and eIF5A were significantly down-regulated in the cytoplasm of UC. eIF5A and eIF6 were significantly down-regulated in the nuclei of UC. CONCLUSION: Dysregulation of eIFs in the urothelium of the urinary bladder is linked to carcinogenesis at this site.

Monoclonal Antibody Therapy for COVID-19: A Retrospective Observational Study at a Regional Hospital.

BACKGROUND: Monoclonal antibodies represent one option for treatment of COVID-19 early after infection. Although large clinical trials have been successfully conducted, real world data are needed to obtain a realistic assessment of the assumed effect on hospitalization rates. METHODS: For this retrospective, observational study, clinical data were collected in 2021 from outpatients (402) as well as hospitalized patients (350) receiving monoclonal antibodies Bamlanivimab, Casirivimab/Imdevimab or Etesevimab/Bamlanivimab. These data were compared with data from a control group of patients not receiving antibodies because admission to the hospital was too late for this therapy. RESULTS: Both groups showed a comparable spectrum of risk factors. Due to the late hospitalization of control patients, a higher frequency of severe symptoms, such as fever, dyspnea, syncope and lower viral load, were observed. CRP and leukocytes counts were also higher in the untreated group. Most importantly, hospitalization time was significantly shorter and the number of deaths was also lower in the treated group. CONCLUSIONS: Apparently, the application of anti-SARS-CoV-2 antibodies reduced the work load of our hospital as shown by the shorter hospitalization time and lower number of COVID-19-related deaths.

Relationship of micro-RNA, mRNA and eIF Expression in Tamoxifen-Adapted MCF-7 Breast Cancer Cells: Impact of miR-1972 on Gene Expression, Proliferation and Migration.

BACKGROUND: Tamoxifen-adapted MCF-7-Tam cells represent an in-vitro model for acquired tamoxifen resistance, which is still a problem in clinics. We here investigated the correlation of microRNA-, mRNA- and eukaryotic initiation factors (eIFs) expression in this model. METHODS: MicroRNA- and gene expression were analyzed by nCounter and qRT-PCR technology; eIFs by Western blotting. Protein translation mode was determined using a reporter gene assay. Cells were transfected with a miR-1972-mimic. RESULTS: miR-181b-5p,-3p and miR-455-5p were up-, miR-375, and miR-1972 down-regulated and are significant in survival analysis. About 5% of the predicted target genes were significantly altered. Pathway enrichment analysis suggested a contribution of the FoxO1 pathway. The ratio of polio-IRES driven to cap-dependent protein translation shifted towards cap-dependent initiation. Protein expression of eIF2A, -4G, -4H and -6 decreased, whereas eIF3H was higher in MCF-7-Tam. Significant correlations between tamoxifen-regulated miRNAs and eIFs were found in representative breast cancer cell lines. Transfection with a miR-1972-mimic reverses tamoxifen-induced expression for a subset of genes and increased proliferation in MCF-7, but reduced proliferation in MCF-7-Tam, especially in the presence of 4OH-tamoxifen. Migration was inhibited in MCF-7-Tam cells. Translation mode remained unaffected. CONCLUSIONS: miR-1972 contributes to the orchestration of gene-expression and physiological consequences of tamoxifen adaption.

BCL3 expression is strongly associated with the occurrence of breast cancer relapse under tamoxifen treatment in a retrospective cohort study.

Patients with estrogen receptor positive breast cancer are usually receiving an anti-estrogen therapy by either aromatase inhibitors or selective estrogen receptor mediators such as tamoxifen. Nevertheless, acquired resistance to tamoxifen under treatment frequently hampers therapy. One proposed explanation for this phenomenon is the interaction of the tumor cells with cells of the tumor microenvironment via the Insulin-like growth factor RNA binding protein 5/B-cell lymphoma 3 (IGFBP5/BCL3) axis. Here we investigated whether a high expression of BCL3 either cytoplasmic or nuclear is associated with the occurrence of a relapse under anti-estrogen therapy in patients. Formaldehyde-fixed, paraffin-embedded samples of 180 breast cancer patients were analyzed for BCL3 expression by immunohistochemistry. An immunoreactive score (IRS) was calculated from staining intensity in cytoplasm and nucleus as well as the percentage of positive tumor cells. These scores were correlated with clinico-pathological parameters using cross-tabulation analysis and patients' relapse free and overall survival by Kaplan-Meier analysis and Cox regression. A tamoxifen-adapted MCF-7 derived cell line was investigated for BCL3 localization by immunofluorescence. The cytosolic BCL3-IRS significantly correlated with the proliferation marker Ki-67, and with the occurrence of a relapse under tamoxifen treatment. Nuclear score correlated only with tamoxifen-relapse. In survival analysis, both scores were highly significant prognostic factors for relapse free, but not for overall survival. This was especially obvious for estrogen receptor positive and HER2/NEU negative cases as well as lobular breast cancer. Tamoxifen-treated, but not aromatase-treated patients had a poor survival when BCL3 scores were high. A tamoxifen adapted cell line exhibited a reduced expression and mainly nuclear localization of BCL3, compared to the parental estrogen receptor positive cell-line MCF-7. Altogether, these data strongly support a function of BCL3 in tamoxifen resistance and its potential use as a predictive biomarker for tamoxifen resistance.

The tamoxifen-regulated, long non-coding RNA LINC00992 affects proliferation, migration, and expression of tamoxifen resistance-associated genes in MCF-7 breast cancer cells.

Introduction: Tamoxifen-adapted MCF-7 breast cancer cells (MCF-7-TAM-R) are a model for acquired tamoxifen resistance in oestrogen receptor-positive breast cancer. In this system, the expression of long-non-coding RNA LINC00992 is decreased. LINC00992 might therefore contribute to tamoxifen adaption and associated gene expres-sion changes. Here, we investigated whether a modulation of LINC00992 modifies gene expression, proliferation, and migration. Material and methods: Up- and down-- regulation of LINC00992 was performed using plasmid vectors and siRNA. Gene expression was measured via nCounter® and quantitative real-time polymerase chain reaction. Database analysis was performed using GEPIA2 and cBioportal. Furthermore, we performed scratch assays, colony-forming assays, and proliferation assays with MCF-7 and MCF-7-TAM-R after up-regulation of LINC00992. Results: Up- and down-regulation of LINC00992 caused gene expression changes in 4 of the 42 tamoxifen-regulated genes tested. Especially ubiquitin D, single-minded homologue 1 (SIM1) carcinoembryonic antigen-related cell adhesion molecule 5 and the G-protein coupled oestrogen receptor 1 were affected. In tamoxifen-adapted MCF-7-TAM-R cells, LINC00992 overexpression resulted in augmented viability and proliferation and enhanced migration. Database analyses revealed that luminal breast cancers have increased expression of LINC00992 compared to Her2-type/neu- or basal type. Furthermore, higher expression of LINC00992 was associated with poor prognosis in luminal-A carcinomas. Conclusions: Changes in the expression of tamoxifen-regulated genes could be induced by manipulating LINC00992's abundance, suggesting that it is at least partially involved in the establishment of the tamoxifen-induced gene expression pattern. LINC00992 may also serve as a prognostic biomarker and may indicate the development of tamoxifen resistance.

The impact of G protein-coupled oestrogen receptor 1 on male breast cancer: a retrospective analysis.

INTRODUCTION: The G protein-coupled oestrogen receptor 1 (GPER-1) is a potential prognostic marker in breast cancer. However, its role in male breast cancer (MBC) is still unknown. This study evaluates the expression of GPER-1 in MBC samples and correlates these data with clinical and pathological parameters including patients' survival. MATERIAL AND METHODS: For this retrospective analysis of a prospectively maintained cohort of patients with MBC, we examined 161 specimens for GPER-1 expression using immunohistochemistry. An immunoreactive score (IRS) was calculated based on staining intensity and the percentage of positive tumour cells. Then, we correlated GPER-1 IRS with clinical and pathological parameters, and overall and relapse-free survival. RESULTS: About 40% of MBC samples were positive for GPER-1 expression (IRS ≥ 4). There was no significant correlation with clinicopathological parameters, such as hormone receptor status or grading. However, a statistical trend was observed for tumour size (≥ 2 cm, p = 0.093). Kaplan-Meier survival analysis revealed no significant correlation with relapse-free survival. However, there was a significant correlation with overall survival, but when we adjusted the log-rank p-value to compensate for the cut-off point optimization method, it rose above 0.1. Additionally, GPER-1-positive patients were older at diagnosis. When adjusted for age by multivariable Cox regression analysis, the significance of GPER-1 status for survival was further reduced. CONCLUSIONS: We found no significant prognostic value of GPER-1 in this MBC cohort as anticipated from studies on female BC. Future studies with higher sample size are needed to further verify a potential sex-specific role of GPER-1.

The predictive potential of Neuronatin for neoadjuvant chemotherapy of breast cancer.

BACKGROUND: Neuronatin (NNAT) determined by immunohistochemistry is a negative prognostic biomarker for breast cancer, independent of the major clinicopathological markers. OBJECTIVE: Here, we investigated whether NNAT is also a predictive biomarker for pathological remission after neoadjuvant chemotherapy. METHODS: One hundred and four breast cancer patients, treated with systemic neoadjuvant chemotherapy were included in this retrospective study. NNAT was detected in formaldehyde fixed, paraffin embedded primary cancer tissue by immunohistochemistry and an immuno-reactive score (IRS) determined. Pathological remission was scored according to Sinn and by evaluation of cytopathic effects. NNAT-IRS was correlated with clinicopathological parameters as well as relapse free and overall survival and for pathological remission after neoadjuvant therapy. RESULTS: NNAT IRS was an independent prognostic marker for relapse free and overall survival and the time from diagnosis to the "tumor-free" state. NNAT IRS was associated with Luminal-A tumors and correlated slightly negative with age and lymph-node metastasis. There was no significant correlation of NNAT-IRS with Sinn's remission score, but with cytopathic effects of chemotherapy. CONCLUSIONS: We confirmed the prognostic impact of NNAT-IRS in an independent cohort of neoadjuvantly treated patients. Additionally, a correlation with a score for pathological remission under systemic neoadjuvant chemotherapy for breast cancer was found.

Interactome Mapping of eIF3A in a Colon Cancer and an Immortalized Embryonic Cell Line Using Proximity-Dependent Biotin Identification.

Translation initiation comprises complex interactions of eukaryotic initiation factor (eIF) subunits and the structural elements of the mRNAs. Translation initiation is a key process for building the cell's proteome. It not only determines the total amount of protein synthesized but also controls the translation efficiency for individual transcripts, which is important for cancer or ageing. Thus, understanding protein interactions during translation initiation is one key that contributes to understanding how the eIF subunit composition influences translation or other pathways not yet attributed to eIFs. We applied the BioID technique to two rapidly dividing cell lines (the immortalized embryonic cell line HEK-293T and the colon carcinoma cell line HCT-166) in order to identify interacting proteins of eIF3A, a core subunit of the eukaryotic initiation factor 3 complex. We identified a total of 84 interacting proteins, with very few proteins being specific to one cell line. When protein biosynthesis was blocked by thapsigargin-induced endoplasmic reticulum (ER) stress, the interacting proteins were considerably smaller in number. In terms of gene ontology, although eIF3A interactors are mainly part of the translation machinery, protein folding and RNA binding were also found. Cells suffering from ER-stress show a few remaining interactors which are mainly ribosomal proteins or involved in RNA-binding.

Glyoxalase 1 expression analysis by immunohistochemistry in breast cancer.

Glyoxalase-1 (GLO-1) is the key enzyme in aldehyde defence in cancer cells. We here evaluated the prognostic impact and association with clinico-pathological parameters and relapse-free as well as overall survival in tumor samples from 187 breast cancer patients. The determined GLO1-immunoreactive score (GLO1-IRS) did not correlate with parameters such as grading, size, hormone receptors or ki67. However, an association of GLO1-IRS with the advanced glycation end product Nε-(carboxymethyl)lysine (p = 0.07) and HER2 (p = 0.06), and a strong correlation with VEGF (p = 0.008) was found. In survival analysis, no significant impact of GLO-1 IRS could be deduced for all patients. However, GLO1-IRS correlated with treatment by radiotherapy (p = 0.008) and high GLO1-IRS predicted a shorter relapse free survival after radiotherapy (log-rank p = 0.067). METABRIC- and TCGA expression-data were analyzed for correlation of regulatory genes of the NF-κB-pathway (RELA, RELB, IRAK1), the oxidative-stress associated transcription factor nrf2 (NFE2L2), the receptor for AGEs (AGER, RAGE) as well as enzymes associated with aldehyde defense. Here, RELA, RELB and NFE2L2 correlated significantly with GLO1 expression, but there were conflicting results between the two data sources. In conclusion, GLO1 was highly expressed in cancer cells, correlated surprisingly weak with survival, but we could show a positive association with the AGE CML as well as VEGF. Gene expression data suggest a regulation of GLO-1 mRNA via both, inflammation (NF-kB) and oxidative stress (NFE2L2) in tumors.

Impact of Eukaryotic Translation Initiation Factors on Breast Cancer: Still Much to Investigate.

Breast carcinoma (BC) remains one of the most serious health problems. It is a heterogeneous entity, and mainly classified according to receptor status for estrogen (ER), progesterone (PR) and egf (HER2/Neu), as well as the proliferation marker ki67. Gene expression in eukaryotes is regulated at the level of both gene transcription and translation, where eukaryotic initiation factors (eIFs) are key regulators of protein biosynthesis. Aberrant translation results in an altered cellular proteome, and this clearly effects cell growth supporting tumorigenesis. The relationship between various eIFs and BC entities, as well as the related regulatory mechanisms, has meanwhile become a focus of scientific interest. Here, we give an overview on the current research state of eIF function, focusing on BC.

IGF2 mRNA Binding Protein 2 Transgenic Mice Are More Prone to Develop a Ductular Reaction and to Progress Toward Cirrhosis.

The insulin-like growth factor 2 (IGF2) mRNA binding proteins (IMPs/IGF2BPs) IMP1 and 3 are regarded as oncofetal proteins, whereas the hepatic IMP2 expression in adults is controversially discussed. The splice variant IMP2-2/p62 promotes steatohepatitis and hepatocellular carcinoma. Aim of this study was to clarify whether IMP2 is expressed in the adult liver and influences progression toward cirrhosis. IMP2 was expressed at higher levels in embryonic compared to adult tissues as quantified in embryonic, newborn, and adult C57BL/6J mouse livers and suggested by analysis of publicly available human data. In an IMP2-2 transgenic mouse model microarray and qPCR analyses revealed increased expression of liver progenitor cell (LPC) markers Bex1, Prom1, Spp1, and Cdh1 indicating a de-differentiated liver cell phenotype. Induction of these LPC markers was confirmed in human cirrhotic tissue datasets. The LPC marker SPP1 has been described to play a major role in fibrogenesis. Thus, DNA methylation was investigated in order to decipher the regulatory mechanism of Spp1 induction. In IMP2-2 transgenic mouse livers single CpG sites were differentially methylated, as quantified by amplicon sequencing, whereas human HCC samples of a human publicly available dataset showed promoter hypomethylation. In order to study the impact of IMP2 on fibrogenesis in the context of steatohepatitis wild-type or IMP2-2 transgenic mice were fed either a methionine-choline deficient (MCD) or a control diet for 2-12 weeks. MCD-fed IMP2-2 transgenic mice showed a higher incidence of ductular reaction (DR), accompanied by hepatic stellate cell activation, extracellular matrix (ECM) deposition, and induction of the LPC markers Spp1, Cdh1, and Afp suggesting the occurrence of de-differentiated cells in transgenic livers. In human cirrhotic samples IMP2 overexpression correlated with LPC marker and ECM component expression. Progression of liver disease was induced by combined MCD and diethylnitrosamine (DEN) treatment. Combined MCD-DEN treatment resulted in shorter survival of IMP2-2 transgenic compared to wild-type mice. Only IMP2-2 transgenic livers progressed to cirrhosis, which was accompanied by strong DR. In conclusion, IMP2 is an oncofetal protein in the liver that promotes DR characterized by de-differentiated cells toward steatohepatitis-associated cirrhosis development with poor survival.

G-Protein-Coupled Estrogen Receptor (GPER)-Specific Agonist G1 Induces ER Stress Leading to Cell Death in MCF-7 Cells.

The G-protein-coupled estrogen receptor (GPER) mediates rapid non-genomic effects of estrogen. Although GPER is able to induce proliferation, it is down-regulated in breast, ovarian and colorectal cancer. During cancer progression, high expression levels of GPER are favorable for patients' survival. The GPER-specific agonist G1 leads to an inhibition of cell proliferation and an elevated level of intracellular calcium (Ca2+). The purpose of this study is to elucidate the mechanism of G1-induced cell death by focusing on the connection between G1-induced Ca2+ depletion and endoplasmic reticulum (ER) stress in the estrogen receptor positive breast cancer cell line MCF-7. We found that G1-induced ER Ca2+ efflux led to the activation of the unfolded protein response (UPR), indicated by the phosphorylation of IRE1α and PERK and the cleavage of ATF6. The pro-survival UPR signaling was activated via up-regulation of the ER chaperon protein GRP78 and translational attenuation indicated by eIF2-α phosphorylation. However, the accompanying pro-death UPR signaling is profoundly activated and responsible for ER stress-induced cell death. Mechanistically, PERK-phosphorylation-induced JNK-phosphorylation and IRE1α-phosphorylation, which further triggered CAMKII-phosphorylation, are both implicated in G1-induced cell death. Our study indicates that loss of ER Ca2+ is responsible for G1-induced cell death via the pro-death UPR signaling.

Time resolved gene expression analysis during tamoxifen adaption of MCF-7 cells identifies long non-coding RNAs with prognostic impact.

Acquired tamoxifen resistance is a persistent problem for the treatment of estrogen receptor positive, premenopausal breast cancer patients and predictive biomarkers are still elusive. We here analyzed gene expression changes in a cellular model to identify early and late changes upon tamoxifen exposure and thereby novel prognostic biomarkers. Estrogen receptor positive MCF-7 cells were incubated with 4OH-tamoxifen (10 nM) and gene expression analyzed by array hybridization during 12 weeks. Array results were confirmed by nCounter- and qRT-PCR technique. Pathway enrichment analysis revealed that early responses concerned mainly amine synthesis and NRF2-related signaling and evolved into a stable gene expression pattern within 4 weeks characterized by changes in glucuronidation-, estrogen metabolism-, nuclear receptor- and interferon signaling pathways. As a large number of long non coding RNAs was subject to regulation, we investigated 5 of these (linc01213, linc00632 linc0992, LOC101929547 and XR_133213) in more detail. From these, only linc01213 was upregulated but all were less abundant in estrogen-receptor negative cell lines (MDA-MB 231, SKBR-3 and UACC3199). In a web-based survival analysis linc01213 and linc00632 turned out to have prognostic impact. Linc01213 was investigated further by plasmid-mediated over-expression as well as siRNA down-regulation in MCF-7 cells. Nevertheless, this had no effect on proliferation or expression of tamoxifen regulated genes, but migration was increased. In conclusion, the cellular model identified a set of lincRNAs with prognostic relevance for breast cancer. One of these, linc01213 although regulated by 4OH-tamoxifen, is not a central regulator of tamoxifen adaption, but interferes with the regulation of migration.

G-protein-coupled estrogen receptor GPER-1 expression in hormone receptor-positive breast cancer is associated with poor benefit of tamoxifen.

BACKGROUND: The role of G-protein-coupled estrogen receptor 1 (GPER-1) in the development of tamoxifen resistance in breast cancer is a highly controversial issue. The aim of this study was to determine the expression of GPER-1 in the clinical routine under conditions of endocrine treatment. PATIENTS AND METHODS: GPER-1 expression was analyzed in 442 patients with primary invasive breast cancer. GPER-1 score of > 3 was determined as positive. Expression data were correlated with clinical and pathological characteristics and patient survival. RESULTS: GPER-1 expression was observed in 352 (80.9%) cases, and positively correlated with estrogen and progesterone receptor status (p = 0.0001). GPER-1 positivity was associated with an increased grade of differentiation (p = 0.0001) and with a low level of Ki-67 expression (p = 0.0001). High GPER-1 expression was associated with a decreased level upon systemic treatment (p = 0.011). In the whole cohort, GPER-1 expression was associated with prolonged disease-free survival (DFS). DFS between tamoxifen- and aromatase inhibitor-treated GPER-1-positive patients was similar (p = 0.090). Notably, after matching the analysis for the most important prognostic factors, DFS for tamoxifen-treated GPER-1-positive patients was 69.1%, which is a percentage that is significantly lower compared to DFS for GPER-1-positive patients treated with aromatase inhibitors (92.7%) (p = 0.005). CONCLUSION: GPER-1 expression is a favorable prognostic factor in breast cancer patients. Its predictive role for poor benefit form tamoxifen treatment should be investigated in further studies.

High neuronatin (NNAT) expression is associated with poor outcome in breast cancer.

Neuronatin (NNAT) is a proteolipid involved in cation homeostasis especially in the developing brain. Its expression has been associated with the progression of lung cancer, glioblastoma, and neuroblastoma as well as glucose induced apoptosis in pancreatic cells. We performed a retrospective study of 148 breast cancer specimens for NNAT expression by immunohistochemistry to evaluate this protein as a prognostic marker for breast cancer. We found a high NNAT immunoreactivity score (by multivariate cox regression) to be an independent prognostic marker for relapse-free (hazard ratio HR = 3.55, p = 0.002) and overall survival (HR = 6.29, p < 0.001). However, NNAT expression was not associated with classical parameters such as hormone receptor expression (p = 0.86) or lymph node metastasis (p = 0.83). Additional independent risk factors in this study population were tumor size (≤2 cm; overall survival: HR = 0.36, p = 0.023; relapse-free survival: HR = 0.26, p < 0.01) and blood vessel infiltration (overall survival: HR = 0.34 p < 0.01). NNAT expression determined by immunohistochemistry might therefore become a helpful additional biomarker to identify high-risk breast cancer patients.

The receptor for advanced glycation end products RAGE is involved in corneal healing.

Impaired corneal healing is still a major cause of blindness. As RAGE (receptor for advanced glycation endproducts) is involved in inflammation and wound healing in other tissues, we here investigated its relevance for corneal wound healing. Corneal re-epithelialization after alkaline injury was analysed in an ex-vivo approach with cultured, enucleated eyes from mice either of the C57Bl/6 NChR genotype (RAGE+/+) and mice of the same strain lacking the RAGE gene (RAGE-/-). The wound area was determined time dependently by fluorescence imaging using fluorescein staining. The eyes of RAGE-/- mice showed a significantly slower re-epithelialization than eyes of the RAGE+/- and the RAGE+/+ genotype. In immunohistochemistry, RAGE expression was increased in wounded corneas whereas the abundance of the RAGE ligand HMGB1 was unaffected, but an increase in S100b-like proteins was revealed upon injury. However, neither the addition of the RAGE agonist HMGB1 or an HMGB1 antagonising antibody nor bovine S100b protein to the culture medium of the wounded eyes had an effect on corneal wound closure in ex-vivo. Further gene expression analysis by RT-PCR demonstrated an increase in RAGE expression on the mRNA level, no significant regulation of HMGB1 and a differential regulation of the S100 gene family after alkaline burn of the cornea. In conclusion, RAGE is clearly involved in corneal re-epithelialization most probably mediated by signalling via S100 proteins.

Systemic activation of NF-κB driven luciferase activity in transgenic mice fed advanced glycation end products modified albumin.

Advanced glycation end products (AGEs) are stable end products of the Maillard reaction and accumulate with progressing ageing and degenerative diseases. Significant amounts of AGE-modified peptides are also consumed with processed food. AGEs bind to specific receptors, especially the receptor of AGEs (RAGE). Activation of RAGE then evokes intracellular signalling, finally resulting in the activation of the NF-κB transcription factor and therefore a proinflammatory state. We here analysed, whether NF-κB is activated in short term upon feeding an AGE-modified protein in-vivo. Transgenic mice expressing firefly luciferase under the control of an NF-κB responsive promoter were intraperitoneally injected or fed with AGE-modified- or control albumin and luciferase expression was analysed by in-vivo imaging and by in-vitro by determination of luciferase enzyme activity in heart, lung, gut, spleen, liver and kidney. In all organs, an activation of the luciferase reporter gene was observed in response to AGE-BSA feeding, however with different intensity and timing. The gut exhibited highest luciferase activity and this activity peaked 6-8 h post AGE-feeding. In heart and kidney, luciferase activity increased for up to 12 h post feeding. All other organs tested, exhibited highest activity at 10 h after AGE-consumption. Altogether, these data demonstrate that feeding AGE-modified protein resulted in a transient and systemic activation of the NF-κB reporter.