Alterations in cell growth and signaling in ErbB3 binding protein-1 (Ebp1) deficient mice

Background  

The ErbB3 binding protein-1 (Ebp1) belongs to a family of DNA/RNA binding proteins implicated in cell growth, apoptosis and differentiation. However, the physiological role of Ebp1 in the whole organism is not known. Therefore, we generated Ebp1-deficient mice carrying a gene trap insertion in intron 2 of the Ebp1 (pa2g4) gene.     

Colocalization of somatostatin receptors and epidermal growth factor receptors in breast cancer cells

Background  

Somatostatin receptor (SSTR) expression is positively correlated with tumor size and inversely correlated with epidermal growth factor receptor (ErbB) levels and tumor differentiation. In the present study, we compared SSTR1-5 and ErbB1-4 mRNA and protein expression in two breast cancer cell lines: MCF-7 (ER+) and MDA-MB-231 (ERα-).     

Down-regulation of the ErbB3 binding protein 1 in human bladder cancer promotes tumor progression and cell proliferation

The ErbB3 binding protein 1 (Ebp1) represents a downstream effector of the ErbB signaling network and has been demonstrated to be a potent tumor suppressor in various human malignancies, however, its involvement in human bladder cancer is still unclear.To investigate the clinical significance and potential role of ErbB3 binding protein 1 (Ebp1) in bladder cancer. Ebp1 expression at protein and gene levels in 52 surgically removed bladder cancer specimens as well as 21 adjacent normal bladder specimens were respectively detected by immunohistochemistry and qRT-PCR. The association of Ebp1 protein expression with the clinicopathological features of bladder cancer was also statistically analyzed. Its roles in bladder cancer cell line were further evaluated. The expression level of Ebp1 protein and gene in bladder cancer tissues was significantly lower than that in adjacent normal bladder tissues (P < 0.01). When categorized into low vs. high expression, the down-regulation of Ebp1 protein was associated with the advanced pathologic stage (P = 0.036) and the high histologic grade (P = 0.001) of patients with bladder cancer. Moreover, following the transfection of Ebp1 in bladder cancer cells, not only cell proliferation and cell invasion decreased significantly, but also the cell cycle was blocked at G0/G1 stage. Our data suggest for the first time that the down-regulation of Ebp1 closely correlates with advanced clinicopathological characteristics of human bladder cancer. Furthermore, Ebp1 plays an important role in the bladder cancer cells’ proliferation by regulating the cancer cell cycle from G0/G1 to S.     

Long noncoding RNA LINC00978 promotes cancer growth and acts as a diagnostic biomarker in gastric cancer

Objectives

Long noncoding RNAs (lncRNAs) play important roles in cancer development and progression. The deregulated expression of LINC00978 has been reported in human cancers. However, the expression pattern and biological roles of LINC00978 in gastric cancer (GC) remain unclear. In this study, we investigated the potential roles and clinical value of LINC00978 in gastric cancer.

Materials and methods

QRT‐PCR was performed to investigate the expression of LINC00978 in gastric cancer cell lines, tissues and serum samples. Cell counting, colony formation, transwell migration and matrigel invasion assays were performed to determine the effects of shRNA‐mediated knockdown of LINC00978 on gastric cancer cell functions. In vivo tumour growth assay was also conducted. Flow cytometry, immunohistochemistry, western blot and qRT‐PCR were used for potential mechanism study.

Results

LINC00978 expression level was elevated in GC tumour tissues, serum samples and cell lines. The expression level of LINC00978 was significantly correlated with tumour size (P = 0.02), lymphatic metastasis (P = 0.009) and TNM stage (P = 0.009). LINC00978 knockdown inhibited the proliferation of GC cells by suppressing cell cycle progression and inducing apoptosis. LINC00978 knockdown also inhibited the migration and invasion of GC cells. In addition, LINC00978 knockdown inhibited the activation of TGF‐β/SMAD signalling pathway and the process of epithelial‐mesenchymal transition (EMT) in GC cells. Moreover, the in vivo tumorigenicity of LINC00978 knockdown GC cells in mice was significantly decreased.

Conclusions

LINC00978 promotes gastric cancer progression and may serve as a potential biomarker for GC.     

Ebp1 regulates myogenic differentiation of myoblast cells via SMAD2/3 signaling pathway

Regulation of skeletal muscle development requires many of the regulatory networks that are fundamental to developmental myogenesis. ErbB3 binding protein‐1 (Ebp1) is involved in the control of myoblasts development in chicken. However, the expression and biological functions of Ebp1 in the progress of myogenesis are unclear. This study focused on determining the effect of Ebp1 on myogenic proliferation and differentiation using a primary myoblasts culture model. Ebp1 was found to upregulate in proliferating myoblasts and decrease at the early stage of myogenic differentiation. The level of endogenous Ebp1 increased from E9 to E20 chicken leg muscles. Knockdown of Ebp1 had no effect on myoblasts proliferation. However, myogenic differentiation into multinucleated myotubes was significantly reduced. The mRNA and protein expression of MRFs was decreased when Ebp1 was knocked down. Downregulation of Ebp1, accompanied by elevated levels of pSMAD2/3, suggests that Ebp1 is involved in regulating myogenic differentiation via SMAD2/3 inhibition. The phosphorylation of SMAD2/3 was activated and the expression of MYOD and MYOG was reduced in Ebp1 knockdown myoblasts, but addition of LY2109761 (an inhibitor specified to SMAD2/3) blocked these effects. Collectively, these results indicate that Ebp1 promotes myoblast differentiation by inhibition of SMAD2/3 signaling pathway during chicken myogenesis. These data provide new insights into the biological role of Ebp1 in embryonic chicken skeletal muscle development.     

P42 Ebp1 functions as a tumor suppressor in non-small cell lung cancer

Although the short isoform of ErbB3-binding protein 1 (Ebp1), p42 has been considered to be a potent tumor suppressor in a number of human cancers, whether p42 suppresses tumorigenesis of lung cancer cells has never been clarified. In the current study we investigated the tumor suppressor role of p42 in non-small cell lung cancer cells. Our data suggest that the expression level of p42 is inversely correlated with the cancerous properties of NSCLC cells and that ectopic expression of p42 is sufficient to inhibit cell proliferation, anchorage-independent growth, and invasion as well as tumor growth in vivo. Interestingly, p42 suppresses Akt activation and overexpression of a constitutively active form of Akt restores the tumorigenic activity of A549 cells that is ablated by exogenous p42 expression. Thus, we propose that p42 Ebp1 functions as a potent tumor suppressor of NSCLC through interruption of Akt signaling. [BMB Reports 2015; 48(3): 159-165]     

MUC4 Overexpression Augments Cell Migration and Metastasis through EGFR Family Proteins in Triple Negative Breast Cancer Cells

Introduction

Current studies indicate that triple negative breast cancer (TNBC), an aggressive breast cancer subtype, is associated with poor prognosis and an early pattern of metastasis. Emerging evidence suggests that MUC4 mucin is associated with metastasis of various cancers, including breast cancer. However, the functional role of MUC4 remains unclear in breast cancers, especially in TNBCs.

Method

In the present study, we investigated the functional and mechanistic roles of MUC4 in potentiating pathogenic signals including EGFR family proteins to promote TNBC aggressiveness using in vitro and in vivo studies. Further, we studied the expression of MUC4 in invasive TNBC tissue and normal breast tissue by immunostaining.

Results

MUC4 promotes proliferation, anchorage-dependent and-independent growth of TNBC cells, augments TNBC cell migratory and invasive potential in vitro, and enhances tumorigenicity and metastasis in vivo. In addition, our studies demonstrated that MUC4 up-regulates the EGFR family of proteins, and augments downstream Erk1/2, PKC-γ, and FAK mediated oncogenic signaling. Moreover, our studies also showed that knockdown of MUC4 in TNBC cells induced molecular changes suggestive of mesenchymal to epithelial transition. We also demonstrated in this study, for the first time, that knockdown of MUC4 was associated with reduced expression of EGFR and ErbB3 (EGFR family proteins) in TNBC cells, suggesting that MUC4 uses an alternative to ErbB2 mechanism to promote aggressiveness. We further demonstrate that MUC4 is differentially over-expressed in invasive TNBC tissues compared to normal breast tissue.

Conclusions

MUC4 mucin expression is associated with TNBC pathobiology, and its knockdown reduced aggressiveness in vitro, and tumorigenesis and metastasis in vivo. Overall, our findings suggest that MUC4 mucin promotes invasive activities of TNBC cells by altering the expression of EGFR, ErbB2, and ErbB3 molecules and their downstream signaling.     

Inhibition of androgen-independent prostate cancer cell growth is enhanced by combination therapy targeting Hedgehog and ErbB signalling

Background  

Prostate cancer is a leading cause of male cancer specific mortality. When cure by radical prostatectomy is not possible the next line of prostate cancer treatment is androgen deprivation. However prolonged androgen deprivation often results in relapse and androgen-independent prostate cancer that is inevitably fatal despite optimal chemotherapy. The Hedgehog signalling pathway has recently been implicated in prostate cancer development and metastasis. EGFR or ErbB2 expression has been also correlated with androgen independence, shorter survival and metastasis.     

Confirmation of human protein interaction data by human expression data

Background  

With microarray technology the expression of thousands of genes can be measured simultaneously. It is well known that the expression levels of genes of interacting proteins are correlated significantly more strongly in Saccharomyces cerevisiae than those of proteins that are not interacting. The objective of this work is to investigate whether this observation extends to the human genome.     

Interleukin-1α enhances the aggressive behavior of pancreatic cancer cells by regulating the α6β1-integrin and urokinase plasminogen activator receptor expression

Background  

In human pancreatic cancer progression, the α₆β₁-integrin is expressed on cancer cell surface during invasion and metastasis formation. In this study, we investigated whether interleukin (IL)-1α induces the alterations of integrin subunits and urokinase plasminogen activator/urokinase plasminogen activator receptor (uPA/uPAR) expression in pancreatic cancer cells. We hypothesize that the alterations of integrin subunits and uPA/uPAR expression make an important role in signaling pathways responsible for biological behavior of pancreatic cancer cells.     

Vertebrate Lrig3-ErbB Interactions Occur In Vitro but Are Unlikely to Play a Role in Lrig3-Dependent Inner Ear Morphogenesis

Background

The Lrig genes encode a family of transmembrane proteins that have been implicated in tumorigenesis, psoriasis, neural crest development, and complex tissue morphogenesis. Whether these diverse phenotypes reflect a single underlying cellular mechanism is not known. However, Lrig proteins contain evolutionarily conserved ectodomains harboring both leucine-rich repeats and immunoglobulin domains, suggesting an ability to bind to common partners. Previous studies revealed that Lrig1 binds to and inhibits members of the ErbB family of receptor tyrosine kinases by inducing receptor internalization and degradation. In addition, other receptor tyrosine kinase binding partners have been identified for both Lrig1 and Lrig3, leaving open the question of whether defective ErbB signaling is responsible for the observed mouse phenotypes.

Methodology/Principal Findings

Here, we report that Lrig3, like Lrig1, is able to interact with ErbB receptors in vitro. We examined the in vivo significance of these interactions in the inner ear, where Lrig3 controls semicircular canal formation by determining the timing and extent of Netrin1 expression in the otic vesicle epithelium. We find that ErbB2 and ErbB3 are present in the early otic epithelium, and that Lrig3 acts cell-autonomously here, as would be predicted if Lrig3 regulates ErbB2/B3 activity. However, inhibition of ErbB activation in the chick otic vesicle has no detectable effect on Netrin gene expression or canal morphogenesis.

Conclusions/Significance

Our results suggest that although both Lrig1 and Lrig3 can interact with ErbB receptors in vitro, modulation of Neuregulin signaling is unlikely to contribute to Lrig3-dependent processes of inner ear morphogenesis. These results highlight the similar binding properties of Lrig1 and Lrig3 and underscore the need to determine how these two family members bind to and regulate different receptors to affect diverse aspects of cell behavior in vivo.     

Down-regulation of sfrp1 in a mammary epithelial cell line promotes the development of a cd44high/cd24low population which is invasive and resistant to anoikis

Background  

The Wnt family of secreted proteins is implicated in the regulation of cell fate during development, as well as in cell proliferation, morphology, and migration. Aberrant activation of the Wnt/β-catenin signaling pathway leads to the development of several human cancers, including breast cancer. Secreted frizzled-related protein 1 (SFRP1) antagonizes this pathway by competing with the Frizzled receptor for Wnt ligands resulting in an attenuation of the signal transduction cascade. Loss of SFRP1 expression is observed in breast cancer, along with several other cancers, and is associated with poor patient prognosis. However, it is not clear whether the loss of SFRP1 expression predisposes the mammary gland to tumorigenesis.     

ErbB2 Receptor Immunoreactivity in Prostate Cancer: Relationship to the Androgen Receptor,Disease Severity at Diagnosis and Disease Outcome

Background

ErbB2 is a member of the epidermal growth factor family of tyrosine kinases that is centrally involved in the pathogenesis of prostate cancer and several studies have reported that a high expression of this protein has prognostic value. In the present study, we have investigated whether tumour ErbB2 immunoreactivity (ErbB2-IR) has clinically useful prognostic value, i.e. that it provides additional prognostic information to that provided by routine clinical tests (Gleason score, tumour stage).

Methodology/Principal Findings

ErbB2-IR was measured in a well-characterised tissue microarray of tumour and non-malignant samples obtained at diagnosis. Additionally, mRNA levels of ErbB2-IR in the prostate were determined in the rat following manipulation of circulating androgen levels. Tumour ErbB2-IR was significantly associated with the downstream signalling molecule phosphorylated-Akt and with the cell proliferation marker Ki-67. The significant association of tumour ErbB2-IR with the Gleason score at diagnosis was lost when controlled for the association of both parameters with Ki-67. In the rat prostate, mRNA for ErbB2 was inversely associated with circulating androgen levels. There was no association between ErbB2-IR and the androgen receptor (AR)-IR in the tumours, but an interaction between the two parameters was seen with respect to their association with the tumour stage. Tumour ErbB2-IR was confirmed to be a prognostic marker for disease-specific survival, but it did not provide significant additive information to the Gleason score or to Ki-67.

Conclusions/Significance

It is concluded that tumour ErbB2-IR is of limited clinical value as a prognostic marker to aid treatment decisions, but could be of pathophysiological importance in prostate cancer.     

A single hydrophobic cleft in the <Emphasis Type="Italic">Escherichia coli</Emphasis> processivity clamp is sufficient to support cell viability and DNA damage-induced mutagenesis <Emphasis Type="Italic">in vivo</Emphasis>

Background  

The ubiquitous family of DnaN sliding processivity clamp proteins plays essential roles in DNA replication, DNA repair, and cell cycle progression, in part by managing the actions of the different proteins involved in these processes. Interactions of the homodimeric Escherichia coli β clamp with its known partners involves multiple surfaces, including a hydrophobic cleft located near the C-terminus of each clamp protomer.     

Troglitazone, a PPAR-γ activator prevents endothelial cell adhesion molecule expression and lymphocyte adhesion mediated by TNF-α

Background  

Cytokine mediated induction of the mucosal addressin cell adhesion molecule-1(MAdCAM-1) expression is associated with the onset and progression of inflammatory bowel disease (IBD).     

Nuclear localization and intensity of staining of nm23 protein is useful marker for breast cancer progression

Background  

Breast cancer is the most common cause of cancer death in the western world. The expression differences of many proteins are associated with breast cancer progression or suppression. The purpose of the study was to determine the expression of nm23 protein in the invasion status and metastatic potential of breast cancer by using tissue microarray and to determine its role in breast cancer based on the expression of nm23 gene product.     

Target selection of soluble protein complexes for structural proteomics studies

Background  

Protein expression in E. coli is the most commonly used system to produce protein for structural studies, because it is fast and inexpensive and can produce large quantity of proteins. However, when proteins from other species such as mammalian are produced in this system, problems of protein expression and solubility arise [1]. Structural genomics project are currently investigating proteomics pipelines that would produce sufficient quantities of recombinant proteins for structural studies of protein complexes. To investigate how the E. coli protein expression system could be used for this purpose, we purified apoptotic binary protein complexes formed between members of the Caspase Associated Recruitment Domain (CARD) family.