Overexpression of ERBB2 in human mammary epithelial cells signals inhibition of transcription of the E-cadherin gene

Characterization and comparison of two NPC cell lines, C17 and C666-1, as models for studying the pathogenesis of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumor that originates from the epithelial cells of the nasopharynx. NPC is closely linked to Epstein-Barr virus (EBV) infection, which necessitates the use of EBV-positive cell lines for accurate pathology studies. In this paper, we present a detailed comparison of the C666-1 and C17 cell lines using bulk RNA-sequencing (RNA-Seq) methods. By thoroughly examining the gene expression profiles of these cell lines, we aim to elucidate the molecular mechanisms that drive NPC progression and metastasis. Understanding these mechanisms is crucial for developing effective treatment strategies. Cancer cell line models are essential in this research, as they provide a controlled environment for studying the complex interplay between viral and host cellular factors. Additionally, our study highlights the differences between the two cell lines, which could be pivotal in designing new experiments and tailoring therapeutic approaches.

Gradients in cell density and shape transitions drive collective cell migration into confining environments

Epithelial cell collectives migrate through tissue interfaces and crevices to orchestrate development processes, tumor invasion, and wound healing. Naturally, the traversal of cell collective through confining environments involves crowding due to narrowing spaces, which seems tenuous given the conventional inverse relationship between cell density and migration. However, the physical transitions required to overcome such epithelial densification for migration across confinements remain unclear. Here, in a system of contiguous microchannels of varying confinements, we show that epithelial (MCF10A) monolayers accumulate higher cell density and undergo fluid-like shape transitions before entering narrower channels. However, overexpression of breast cancer oncogene ErbB2 did not require such accumulation of cell density to migrate across matrix confinement. While wild-type MCF10A cells migrated faster in narrow channels, this confinement sensitivity was reduced after +ErbB2 mutation or with constitutively active RhoA. This physical interpretation of collective cell migration as density and shape transitions in granular matter could advance our understanding of complex living systems.

Transitions in density, pressure, and effective temperature drive collective cell migration into confining environments

Epithelial cell collectives migrate through tissue interfaces and crevices to orchestrate processes of development, tumor invasion, and wound healing. Naturally, traversal of cell collective through confining environments involves crowding due to the narrowing space, which seems tenuous given the conventional inverse relationship between cell density and migration. However, physical transitions required to overcome such epithelial densification for migration across confinements remain unclear. Here, in contiguous microchannels, we show that epithelial (MCF10A) monolayers accumulate higher cell density before entering narrower channels; however, overexpression of breast cancer oncogene +ErbB2 reduced this need for density accumulation across confinement. While wildtype MCF10A cells migrated faster in narrow channels, this confinement sensitivity reduced after +ErbB2 mutation or with constitutively-active RhoA. The migrating collective developed pressure differentials upon encountering microchannels, like fluid flow into narrowing spaces, and this pressure dropped with their continued migration. These transitions of pressure and density altered cell shapes and increased effective temperature, estimated by treating cells as granular thermodynamic system. While +RhoA cells and those in confined regions were effectively warmer, cancer-like +ErbB2 cells remained cooler. Epithelial reinforcement by metformin treatment increased density and temperature differentials across confinement, indicating that higher cell cohesion could reduce unjamming. Our results provide experimental evidence for previously proposed theories of inverse relationship between density and motility-related effective temperature. Indeed, we show across cell lines that confinement increases pressure and effective temperature, which enable migration by reducing density. This physical interpretation of collective cell migration as granular matter could advance our understanding of complex living systems.

A Multi-Center Clinical Study to Harvest and Characterize Circulating Tumor Cells from Patients with Metastatic Breast Cancer Using the Parsortix® PC1 System

Circulating tumor cells (CTCs) captured from the blood of cancer patients may serve as a surrogate source of tumor material that can be obtained via a venipuncture (also known as a liquid biopsy) and used to better understand tumor characteristics. However, the only FDA-cleared CTC assay has been limited to the enumeration of surface marker-defined cells and not further characterization of the CTCs. In this study, we tested the ability of a semi-automated device capable of capturing and harvesting CTCs from peripheral blood based on cell size and deformability, agnostic of cell-surface markers (the Parsortix® PC1 System), to yield CTCs for evaluation by downstream techniques commonly available in clinical laboratories. The data generated from this study were used to support a De Novo request (DEN200062) for the classification of this device, which the FDA recently granted. As part of a multicenter clinical trial, peripheral blood samples from 216 patients with metastatic breast cancer (MBC) and 205 healthy volunteers were subjected to CTC enrichment. A board-certified pathologist enumerated the CTCs from each participant by cytologic evaluation of Wright-Giemsa-stained slides. As proof of principle, cells harvested from a concurrent parallel sample provided by each participant were evaluated using one of three additional evaluation techniques: molecular profiling by qRT-PCR, RNA sequencing, or cytogenetic analysis of HER2 amplification by FISH. The study demonstrated that the Parsortix® PC1 System can effectively capture and harvest CTCs from the peripheral blood of MBC patients and that the harvested cells can be evaluated using orthogonal methodologies such as gene expression and/or Fluorescence In Situ Hybridization (FISH).

Interplay between EGFR, E-cadherin, and PTP1B in epidermal homeostasis

Maintaining epithelial homeostasis is crucial to allow embryo development but also the protective barrier which is ensured by the epidermis. This homeostasis is regulated through the expression of several molecules among which EGFR and E-cadherin which are of major importance. Indeed, defects in the regulation of these proteins lead to abnormalities in cell adhesion, proliferation, differentiation, and migration. Hence, regulation of these two proteins is of the utmost importance as they are involved in numerous skin pathologies and cancers. In the last decades it has been described several pathways of regulation of these two proteins and notably several mechanisms of cross-regulation between these partners. In this review, we aimed to describe the current understanding of the regulation of EGFR and interactions between EGFR and E-cadherin and, in particular, the implication of these cross-regulations in epithelium homeostasis. We pay particular attention to PTP1B, a phosphatase involved in the regulation of EGFR.

Phosphotyrosine isosteres: past, present and future

Tyrosine phosphorylation is a critical component of signal transduction for multicellular organisms, particularly for pathways that regulate cell proliferation and differentiation. While tyrosine kinase inhibitors have become FDA-approved drugs, inhibitors of the other important components of these signaling pathways have been harder to develop. Specifically, direct phosphotyrosine (pTyr) isosteres have been aggressively pursued as inhibitors of Src homology 2 (SH2) domains and protein tyrosine phosphatases (PTPs). Medicinal chemists have produced many classes of peptide and small molecule inhibitors that mimic pTyr. However, balancing affinity with selectivity and cell penetration has made this an extremely difficult space for developing successful clinical candidates. This review will provide a comprehensive picture of the field of pTyr isosteres, from early beginnings to the current state and trajectory. We will also highlight the major protein targets of these medicinal chemistry efforts, the major classes of peptide and small molecule inhibitors that have been developed, and the handful of compounds which have been tested in clinical trials.

Characterizing Metastatic HER2-Positive Gastric Cancer at the CDH1 Haplotype

The CDH1 gene, coding for the E-cadherin protein, is linked to gastric cancer (GC) susceptibility and tumor invasion. The human epidermal growth factor receptor 2 (HER2) is amplified and overexpressed in a portion of GC. HER2 is an established therapeutic target in metastatic GC (mGC). Trastuzumab, in combination with various chemotherapeutic agents, is a standard treatment for these tumors leading to outcome improvement. Unfortunately, the survival benefit is limited to a fraction of patients. The aim of this study was to improve knowledge of the HER2 and the E-cadherin alterations in the context of GC to characterize subtypes of patients that could better benefit from targeted therapy. An association between the P7-CDH1 haplotype, including two polymorphisms (rs16260A-rs1801552T) and a subset of HER2-positive mGC with better prognosis was observed. Results indicated the potential evaluation of CDH1 haplotypes in mGC to stratify patients that will benefit from trastuzumab-based treatments. Moreover, data may have implications to understanding the HER2 and the E-cadherin interactions in vivo and in response to treatments.

Krüppel-like factor 8 involved in hypoxia promotes the invasion and metastasis of gastric cancer via epithelial to mesenchymal transition

Previously, we reported that hypoxia was able to induce invasion and metastasis in gastric cancer and that hypoxia-inducible factor-1 (HIF-1) is a key factor involved in this tumor type. Krüppel-like factor 8 (KLF8) as a transcriptional repressor has been suggested as a promoter of tumor metastasis in breast cancer and an inducer of the epithelial‑mesenchymal transition (EMT). KLF8 is also highly expressed in gastric cancer tissues, contributing to poor prognosis. However, the association between KLF8 and HIF-1 in regulating the progression of human gastric cancer in hypoxia is unclear. In the present study, we found that KLF8 was overexpressed in gastric cancer metastatic tissues and cells. Additionally, KLF8 siRNA significantly inhibited SGC7901 cell invasion and migration compared with SGC7901, SGC7901/Scr-si cells. Hypoxia is thus able to induce KLF8 expression and EMT in SGC7901 cells. However, following the examination of changes in cell morphology and epithelial and mesenchymal markers, it was found that KLF8 siRNA and HIF-1 siRNA strongly reversed EMT in cells undergoing hypoxia. Furthermore, hypoxia-induced KLF8 overexpression was attenuated by HIF-1 siRNA. Experiments using luciferase promoter constructs resulted in a marked increase in the activity of cells exposed to hypoxia and decreased activity in cells co-transfected with HIF-1 siRNA. The chromatin immunoprecipitation assay revealed proximal HRE at -133 is the main HIF-1 binding site in the KLF8 promoter. In conclusion, the results demonstrated that KLF8 is actively enhanced by hypoxia and is a novel HIF-1 target. KLF8 is a novel EMT regulating transcription factor that involved in the progression of gastric cancer. The specific anti-EMT drugs in combination with anti-hypoxia are new promising cancer therapies.

Akt phosphorylates and activates HSF-1 independent of heat shock, leading to Slug overexpression and epithelial-mesenchymal transition (EMT) of HER2-overexpressing breast cancer cells

Epithelial-mesenchymal transition (EMT) is an essential step for tumor progression, although the mechanisms driving EMT are still not fully understood. In an effort to investigate these mechanisms, we observed that heregulin-mediated activation of HER2, or HER2 overexpression, resulted in EMT, which is accompanied with increased expression of a known EMT regulator Slug, but not TWIST or Snail. We then investigated how HER2 induced Slug expression and found, for the first time, that there are four consensus HSF Sequence-binding Elements (HSEs), the binding sites for heat shock factor-1 (HSF-1), located in the Slug promoter. HSF-1 bound to and transactivated the Slug promoter independent of heat shock, leading to Slug expression in breast cancer cells. Mutation of the putative HSEs ablated Slug transcriptional activation induced by heregulin or HSF-1 overexpression. Knockdown of HSF-1 expression by siRNA reduced Slug expression and heregulin-induced EMT. The positive association between HSF-1 and Slug was confirmed by immunohistochemical staining of a cohort of 100 invasive breast carcinoma specimens. While investigating how HER2 activated HSF-1 independent of heat shock, we observed that HER2 activation resulted in concurrent phosphorylation of Akt and HSF-1. We then observed, also for the first time, that Akt directly interacted with HSF-1 and phosphorylated HSF-1 at S326. Inhibition of Akt using siRNA, dominant-negative Akt mutant, or small molecule inhibitors prevented heregulin-induced HSF-1 activation and Slug expression. Conversely, constitutively active Akt induced HSF-1 phosphorylation and Slug expression. HSF-1 knockdown reduced the ability of Akt to induce Slug expression, indicating an essential that HSF-1 plays in Akt-induced Slug upregulation. Together, our study uncovered the existence of a novel Akt-HSF-1 signaling axis that leads to Slug upregulation and EMT, and potentially contributes to progression of HER2-positive breast cancer.

α2β1 Integrin

The α2β1 integrin, also known as VLA-2, GPIa-IIa, CD49b, was first identified as an extracellular matrix receptor for collagens and/or laminins [55, 56]. It is now recognized that the α2β1 integrin serves as a receptor for many matrix and nonmatrix molecules [35, 79, 128]. Extensive analyses have clearly elucidated the α2 I domain structural motifs required for ligand binding, and also defined distinct conformations that lead to inactive, partially active or highly active ligand binding [3, 37, 66, 123, 136, 137, 140]. The mechanisms by which the α2β1 integrin plays a critical role in platelet function and homeostasis have been carefully defined via in vitro and in vivo experiments [76, 104, 117, 125]. Genetic and epidemiologic studies have confirmed human physiology and disease states mediated by this receptor in immunity, cancer, and development [6, 20, 21, 32, 43, 90]. The role of the α2β1 integrin in these multiple complex biologic processes will be discussed in the chapter.

HER2 mediates epidermal growth factor-induced down-regulation of E-cadherin in human ovarian cancer cells

Overexpression of HER2 is correlated with a poor prognosis in many types of human cancers. Due to the interaction between HER2 and other ErbB receptors, HER2 is implicated in the EGF family of ligands-regulated tumor progression. In ovarian cancer, although the relationships between HER2 amplification and patient prognosis remain controversial, the underlying molecular mechanisms of HER2-mediated tumor progression are not fully understood. Our previous studies demonstrated that EGF induces ovarian cancer cell invasion by down-regulating E-cadherin expression through the up-regulation of its transcriptional repressors, Snail and Slug. It has been shown that overexpression of HER2 down-regulates E-cadherin expression in human mammary epithelial cells. However, whether HER2 mediates EGF-induced down-regulation of E-cadherin remains unknown. In this study, we examined the potential role of HER2 in EGF-induced down-regulation of E-cadherin and increased cell invasion. We show that EGF treatment induces the interaction of EGFR with HER2 and increases the activation of HER2 in human ovarian cancer cells; we also show that these effects are diminished by knockdown of EGFR. Importantly, treatment with HER2-specific tyrosine kinase inhibitor, AG825, and HER2 siRNA diminished the up-regulation of Snail and Slug as well as the down-regulation of E-cadherin by EGF. Finally, we also show that EGF-induced cell invasion was attenuated by treatment with HER2 siRNA. This study demonstrates an important role for HER2 in mediating the effects of EGF on Snail, Slug and E-cadherin expression as well as invasiveness in human ovarian cancer cells.

Loss of Par3 promotes breast cancer metastasis by compromising cell-cell cohesion

The mechanisms by which tumour cells metastasize and the role that cell polarity proteins play in this process are not well understood. We report that partitioning defective protein 3 (Par3) is dysregulated in metastasis in human breast cancer, and is associated with a higher tumour grade and ErbB2-positive status. Downregulation of Par3 cooperated with ErbB2 to induce cell invasion and metastasis in vivo. Interestingly, the metastatic behaviour was not associated with an overt mesenchymal phenotype. However, loss of Par3 inhibited E-cadherin junction stability, disrupted membrane and actin dynamics at cell-cell junctions and decreased cell-cell cohesion in a manner dependent on the Tiam1/Rac-GTP pathway. Inhibition of this pathway restored E-cadherin junction stability and blocked invasive behaviour of cells lacking Par3, suggesting that loss of Par3 promotes metastatic behaviour of ErbB2-induced tumour epithelial cells by decreasing cell-cell cohesion.

PAX2 is activated by estradiol in breast cancer cells of the luminal subgroup selectively, to confer a low invasive phenotype

BACKGROUND

Metastasis is the leading cause of death among breast cancer patients. Identifying key cellular factors controlling invasion and metastasis of breast cancer cells should pave the way to new therapeutic strategies efficiently interfering with the metastatic process. PAX2 (paired box 2) transcription factor is expressed by breast cancer cells in vivo and recently, it was shown to negatively regulate the expression of ERBB2 (erythroblastic leukemia viral oncogene homolog 2, HER-2/neu), a well-documented pro-invasive and pro-metastastic gene, in luminal/ERalpha-positive (ERα+) breast cancer cells. The objective of the present study was to investigate a putative role for PAX2 in the control of luminal breast cancer cells invasion, and to begin to characterize its regulation.

RESULTS

PAX2 activity was higher in cell lines from luminal compared to non-luminal subtype, and activation of PAX2 by estradiol was selectively achieved in breast cancer cell lines of the luminal subtype. This process was blocked by ICI 182780 and could be antagonized by IGF-1. Knockdown of PAX2 in luminal MCF-7 cells completely abrogated estradiol-induced downregulation of ERBB2 and decrease of cell invasion, whereas overexpression of PAX2 in these cells enhanced estradiol effects on ERBB2 levels and cell invasion.

CONCLUSIONS

The study demonstrates that PAX2 activation by estradiol is selectively achieved in breast cancer cells of the luminal subtype, via ERα, and identifies IGF-1 as a negative regulator of PAX2 activity in these cells. Further, it reveals a new role for PAX2 in the maintenance of a low invasive behavior in luminal breast cancer cells upon exposure to estradiol, and shows that overexpression and activation of PAX2 in these cells is sufficient to reduce their invasive ability.

Novel method for differentiation between Trastuzumab and host adaptive response

Humoral immune response to human epidermal growth factor receptor 2 (HER-2/neu or ErbB-2) has been detected in sera of breast cancer patients and shown to be an appropriate prognostic marker (Taylor et al., 2007). However, since Trastuzumab (Herceptin) is a widely used monoclonal antibody as cancer therapy agent for tumors over-expressing HER-2, there is a need for an efficient way to detect host-generated antibodies against HER-2 without the confounding effect of Herceptin. Here we describe a screening method developed to decipher between host antibodies against HER-2 and that of Herceptin. By producing a series of truncation mutants within the epitope of Herceptin, we were able to inhibit this binding. We demonstrated also that by a three amino acid substitution (PPF→SSS) we were able to abrogate Herceptin binding while generating a highly conserved HER-2 extracellular domain (ECD). By producing a stable cell line that expresses this mutated form of the human HER-2 ECD, we have a source of this protein to probe patient sera. Our method represents a proof of principle that mutated HER-2 which we constructed could be used to distinguish between a host response against HER-2 and the monoclonal antibody Herceptin targeting the same protein.

The EGFR-GEP100-Arf6-AMAP1 signaling pathway specific to breast cancer invasion and metastasis

Tumors are tissue-specific diseases, and their mechanisms of invasion and metastasis are highly diverse. In breast cancer, biomarkers that specifically correlate with the invasive phenotypes have not been clearly identified. A small GTPase Arf6 primarily regulates recycling of plasma membrane components. We have shown that Arf6 and its effector AMAP1 (DDEF1, DEF1, ASAP1 and centaurin β4) are abnormally overexpressed in some breast cancers and used for their invasion and metastasis. Overexpression of these proteins is independent of the transcriptional upregulation of their genes, and occurs only in highly malignant breast cancer cells. We recently identified GEP100 (BRAG2) to be responsible for the Arf6 activation to induce invasion and metastasis, by directly binding to ligand-activated epidermal growth factor receptor (EGFR). A series of our studies revealed that for activation of the invasion pathway of EGFR, it is prerequisite that Arf6 and AMAP1 both are highly overexpressed, and that EGFR is activated by ligands. Pathological analyses indicate that a significant large population of human ductal cancers may utilize the EGFR-GEP100-Arf6-AMAP1 pathway for their malignancy. Microenvironments have been highly implicated in the malignancy of mammary tumors. Our results reveal an aspect of the precise molecular mechanisms of some breast cancers, in which full invasiveness is not acquired just by intracellular alterations of cancer cells, but extracellular factors from microenvironments may also be necessary. Possible translation of our knowledge to cancer therapeutics will also be discussed.

Human antimicrobial protein hCAP18/LL-37 promotes a metastatic phenotype in breast cancer

Introduction

Human cathelicidin antimicrobial protein, hCAP18, and its C-terminal peptide LL-37 is a multifunctional protein. In addition to being important in antimicrobial defense, it induces chemotaxis, stimulates angiogenesis and promotes tissue repair. We previously showed that human breast cancer cells express high amounts of hCAP18, and hypothesised that hCAP18/LL-37 may be involved in tumour progression.

Methods

hCAP18 mRNA was quantified in 109 primary breast cancers and compared with clinical findings and ERBB2 mRNA expression. Effects of exogenous LL-37 and transgenic overexpression of hCAP18 on ErbB2 signalling were investigated by immunoblotting using extracts from breast cancer cell lines ZR75-1 and derivatives of MCF7. We further analysed the impact of hCAP18/LL-37 on the morphology of breast cancer cells grown in soft agar, on cell migration and on tumour development in severe combined immunodeficiency (SCID) mice.

Results

The expression of hCAP18 correlated closely with that of ERBB2 and with the presence of lymph node metastases in oestrogen receptor-positive tumours. hCAP18/LL-37 amplified Heregulin-induced mitogen-activated protein kinase (MAPK) signalling through ErbB2, identifying a functional association between hCAP18/LL-37 and ErbB2 in breast cancer. Treatment with LL-37 peptide significantly stimulated the migration of breast cancer cells and their colonies acquired a dispersed morphology indicative of increased metastatic potential. A truncated version of LL-37 competitively inhibited LL-37 induced MAPK phosphorylation and significantly reduced the number of altered cancer cell colonies induced by LL-37 as well as suppressed their migration. Transgenic overexpression of hCAP18 in a low malignant breast cancer cell line promoted the development of metastases in SCID mice, and analysis of hCAP18 transgenic tumours showed enhanced activation of MAPK signalling.

Conclusions

Our results provide evidence that hCAP18/LL-37 contributes to breast cancer metastasis.

Neuregulin-mediated ErbB3 signaling is required for formation of zebrafish dorsal root ganglion neurons

Dorsal root ganglia (DRGs) arise from trunk neural crest cells that emerge from the dorsal neuroepithelium and coalesce into segmental streams that migrate ventrally along the developing somites. Proper formation of DRGs involves not only normal trunk neural crest migration, but also the ability of DRG progenitors to pause at a particular target location where they can receive DRG-promoting signals. In mammalian embryos, a receptor tyrosine kinase proto-oncogene, ErbB3, is required for proper trunk neural crest migration. Here, we show that in zebrafish mutants lacking ErbB3 function, neural crest cells do not pause at the location where DRGs normally form and DRG neurons are not generated. We also show that these mutants lack trunk neural crest-derived sympathetic neurons, but that cranial neural crest-derived enteric neurons appear normal. We isolated three genes encoding neuregulins, ErbB3 ligands, and show that two neuregulins function together in zebrafish trunk neural crest cell migration and in DRG formation. Together, our results suggest that ErbB3 signaling is required for normal migration of trunk, but not cranial, neural crest cells.

Prognostic significance of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) expression in relation to cadherin expression in patients with colorectal carcinoma

PURPOSE

This study was designed to assess the prognostic value of receptor-binding cancer antigen expressed on SiSo cells expression and its relationship with cadherin expression in patients with colorectal cancer.

METHODS

The expressions of receptor-binding cancer antigen expressed on SiSo cells and E-cadherin were analyzed with special reference to prognosis in 105 patients with colorectal cancer.

RESULTS

Receptor-binding cancer antigen expressed on SiSo cells immunoreactivity was detected in the membrane and cytoplasm of tumor cells and considered to be positive in 48 patients (45.7 percent). The expression of receptor-binding cancer antigen expressed on SiSo cells was significantly correlated with lymph node metastasis (P = 0.0004), venous invasion (P = 0.0062), Dukes stages (P < 0.0001), and serum levels of carcinoembryonic antigen (P = 0.014). Furthermore, receptor-binding cancer antigen expressed on SiSo cells expression was significantly correlated with a poor prognosis (P < 0.001), and multivariate analysis indicated that it was an independent prognostic indicator. The expression of receptor-binding cancer antigen expressed on SiSo cells was more frequently found in tumors with reduced or abnormal expression of E-cadherin. The survival time of patients with reduced/abnormal E-cadherin expression was significantly shorter than that of patients with normal E-cadherin expression among patients with receptor-binding cancer antigen expressed on SiSo cells expression (P = 0.0043) but did not differ for those without receptor-binding cancer antigen expressed on SiSo cells expression (P = 0.17). Furthermore, multivariate analysis revealed that reduced/abnormal expression of E-cadherin was an independent prognostic factor in patients with receptor-binding cancer antigen expressed on SiSo cells expression but not in those without receptor-binding cancer antigen expressed on SiSo cells expression.

CONCLUSIONS

Receptor-binding cancer antigen expressed on SiSo cells expression is significantly correlated with tumor progression and poor prognosis in patients with colorectal cancer. Both reduced E-cadherin and enhanced receptor-binding cancer antigen expressed on SiSo cells expression may be critical for the mechanism of metastasis and recurrence in human colorectal cancer.

The Prognostic Value of E-cadherin Expression in Breast Cancer

BACKGROUND

Breast cancer continues to be a major cause of morbidity and mortality throughout the world. The behavior of breast cancer varies widely. Several parameters have been investigated to predict the prognosis in breast cancer. But still there is no single parameter that can predict prognosis in an individual patient. Among the novel prognostic markers is E-cadherin; a calcium-dependent epithelial cell adhesion molecule. Its loss has been associated with metastases, thereby providing evidence for its role as an invasion suppressor. The objective of the present study was to assess the prognostic value of E-cadherin expression in breast cancer cases, and its correlations with the other studied prognostic parameters.

METHODS

The study comprised 54 breast cancer patients admitted at King Fahd Specialist Hospital, Qassim during the period 2001-2006. The median tumor size was 3cms. Fifty cases (92.6%) had invasive ductal carcinoma, four cases had lobular carcinomas, and most were grade II (82%), stage II (48%), and the majority of cases had positive axillary lymph nodes (70.3%). Representative sections from formalin-fixed paraffin embedded tissue blocks were taken from the 54 cases of breast cancer, and were stained for E-cadherin expression by immunohistochemical technique (monoclonal E-cadherin (NCL-E-cad), Novocastra). All the lobular carcinoma cases were negative for membranous expression of E-cadherin while 72% of invasive ductal carcinomas were positive for the marker.

RESULTS

A significant correlation was found between strong E-cadherin expression and node negative cases. Node negative cases were found to be an independent predictor of strong E-cadherin expression while node positive cases predicted negative expression of E-cadherin (P = 0 .026). Also loss of E-cadherin was noted in advanced stages of breast cancer supporting the view that loss of E-cadherin expression is a marker of aggressiveness. However, there was no correlation between the E-cadherin and other prognostic parameters as tumor size, tumor grade, ER, PR, and HER-2 expression.

CONCLUSION

A significant correlation was found between strong E-cadherin expression and node negative cases.

Effects of HER2 overexpression on cell signaling networks governing proliferation and migration

Although human epidermal growth factor receptor 2 (HER2) overexpression is implicated in tumor progression for a variety of cancer types, how it dysregulates signaling networks governing cell behavioral functions is poorly understood. To address this problem, we use quantitative mass spectrometry to analyze dynamic effects of HER2 overexpression on phosphotyrosine signaling in human mammary epithelial cells stimulated by epidermal growth factor (EGF) or heregulin (HRG). Data generated from this analysis reveal that EGF stimulation of HER2-overexpressing cells activates multiple signaling pathways to stimulate migration, whereas HRG stimulation of these cells results in amplification of a specific subset of the migration signaling network. Self-organizing map analysis of the phosphoproteomic data set permitted elucidation of network modules differentially regulated in HER2-overexpressing cells in comparison with parental cells for EGF and HRG treatment. Partial least-squares regression analysis of the same data set identified quantitative combinations of signals within the networks that strongly correlate with cell proliferation and migration measured under the same battery of conditions. Combining these modeling approaches enabled association of epidermal growth factor receptor family dimerization to activation of specific phosphorylation sites, which appear to most critically regulate proliferation and/or migration.

CDH1 promoter hypermethylation and E-cadherin protein expression in infiltrating breast cancer

Background

The E-cadherin gene (CDH1) maps, at chromosome 16q22.1, a region often associated with loss of heterozygosity (LOH) in human breast cancer. LOH at this site is thought to lead to loss of function of this tumor suppressor gene and was correlated with decreased disease-free survival, poor prognosis, and metastasis. Differential CpG island methylation in the promoter region of the CDH1 gene might be an alternative way for the loss of expression and function of E-cadherin, leading to loss of tissue integrity, an essential step in tumor progression.

Methods

The aim of our study was to assess, by Methylation-Specific Polymerase Chain Reaction (MSP), the methylation pattern of the CDH1 gene and its possible correlation with the expression of E-cadherin and other standard immunohistochemical parameters (Her-2, ER, PgR, p53, and K-67) in a series of 79 primary breast cancers (71 infiltrating ductal, 5 infiltrating lobular, 1 metaplastic, 1 apocrine, and 1 papillary carcinoma).

Results

CDH1 hypermethylation was observed in 72% of the cases including 52/71 ductal, 4/5 lobular carcinomas and 1 apocrine carcinoma. Reduced levels of E-cadherin protein were observed in 85% of our samples. Although not statistically significant, the levels of E-cadherin expression tended to diminish with the CDH1 promoter region methylation. In the group of 71 ductal cancinomas, most of the cases of showing CDH1 hypermethylation also presented reduced levels of expression of ER and PgR proteins, and a possible association was observed between CDH1 methylation and ER expression (p = 0.0301, Fisher's exact test). However, this finding was not considered significant after Bonferroni correction of p-value.

Conclusion

Our preliminary findings suggested that abnormal CDH1 methylation occurs in high frequencies in infiltrating breast cancers associated with a decrease in E-cadherin expression in a subgroup of cases characterized by loss of expression of other important genes to the mammary carcinogenesis process, probably due to the disruption of the mechanism of maintenance of DNA methylation in tumoral cells.

Distal ERBB2 promoter fragment displays specific transcriptional and nuclear binding activities in ERBB2 overexpressing breast cancer cells

Overexpression of the ERBB2 gene occurs in 30% of human breast cancers and is correlated with poor prognosis. The deregulation is the consequence of an increased transcription level and gene amplification. Several laboratories, including our own, have identified, in the proximal promoter, enhancers implicated in the gene overexpression. However, our previous studies of a 6-kb ERBB2 promoter fragment revealed the presence of repressing fragments, which were able to overcome the effect of the proximal enhancers. These repressing elements were functional in all cell lines, regardless of their endogenous ERBB2 expression level. Here, we show that a distal ERBB2 promoter region restores high transcription rates specifically in ERBB2 overexpressing breast cancer cells. This distal promoter region thus contains enhancers essential for the overexpression of the gene. By EMSA, performed with nuclear extract of cells overexpressing (BT-474) or not (MDA-MB-231) the ERBB2 gene, we show that at least two sequences of the distal promoter region are bound exclusively by BT-474 extract. Further experiments reveal that AP-2 transcription factors contribute to this differential binding activity, by binding recognition sequences located 4500 bp and 4000 bp upstream of the transcription start site. These sites are occupied by AP2 in vivo, as demonstrated by ChIP assay. Inactivation of AP-2 proteins in ERBB2 overexpressing cells reduces the distal promoter activity up to 70%, indicating the AP-2 factors are implicated in the strong distal enhancing effect. Moreover, we identified a 54-bp fragment that is bound specifically by BT-474 nuclear extract. Further experiments did not lead to the identification of the protein responsible for this binding. Our results thus highlight the importance of ERBB2 distal promoter region and further implicate AP-2 in ERBB2 overexpression in breast cancer cells.

Assessment of staging, prognosis and mortality of colorectal cancer by tumor markers: receptor erbB-2 and cadherins

PURPOSE

To evaluate the prognostic significance and correlation with staging and degree of cell differentiation of the tumoral expression of the proteins c-erbB-2 and E-cadherin, in patients with colorectal adenocarcinoma.

METHODS

The study included 117 patients with an average age of 63.1 years and an average follow-up duration of 28.1 months. The disease-free interval, survival, incidence of recurrence and specific mortality were evaluated. c-erbB-2 anti-oncoprotein antibodies (Dako) were utilized via the streptavidin-biotin technique. Samples were considered to be positive for c-erbB-2 if 10% or more of the tumor cell membranes were stained. The anti-E-cadherin antibodies (Dako), evaluated this protein and is considered positive, if 50% or more of the cell membranes were stained. Statistical analysis was performed using Pearson's chi-squared test, Fisher's exact test, Kaplan-Meier's estimator, the log-rank test and Wilcoxon's test (Breslow version), setting the level of statistical significance at 5% (p<0.05).

RESULTS

52 of 108 patients studied for c-erbB-2 were positive (48.1%), 47 of 93 patients studied for E-cadherin were negative (50.5%). These data do not express any correlation with TNM (tumor, node and metastasis) staging and the degree of cell differentiation or with the tumor recurrence rate. The disease-free interval among patients who were positive for c-erbB-2 and negative for E-cadherin was 68.0 months and did not differ from those with c-erbB-2 negative and E-cadherin positive (55.0 months--p = 0.5510). The average survival among patients positive for c-erbB-2 and negative for E-cadherin was 75 months without statistical significance difference with the other group (61 months--p = 0.5256). Specific mortality occurred in 20.0% of the cases and did not correlate with the expression of c-erbB-2 (p=0.446), E-cadherin (p=0.883).

CONCLUSION

The tumoral expression of c-erbB-2 and E-cadherin did not demonstrate a correlation with the staging and degree of cell differentiation, and it did not present prognostic value regarding disease recurrence, disease-free interval, survival and specific mortality among patients with colorectal adenocarcinoma.

ErbB2 growth factor receptor, a marker for neuroendocrine cells?

BACKGROUND/AIMS

The overexpression of ErbB2 in pancreatic cancer has been reported with a varying incidence ranging between 1 and 80%. Our routine examination, however, revealed a consistently strong immunoreactivity of three anti-ErbB2 growth factor receptor antibodies in pancreatic islets and intrapancreatic ganglia. To validate our findings and to understand the reasons for the reported differences in the frequency of ErbB2 overexpression in pancreatic cancer, the following studies were performed.

MATERIALS AND METHODS

Tissue samples from 12 normal pancreata, 7 surgical chronic pancreatitis cases, 21 primary pancreatic adenocarcinomas, 9 metastatic pancreatic adenocarcinomas, and 4 islet cell tumors were subjected to immunohistochemical examination using antibodies from three manufacturers. Cultured human islet cells and pancreatic cancer cell lines, as well as samples from the gastrointestinal tract, the CNS, and the adrenal gland were included in the study. For comparison, mammary cancer tissue and mammary cancer cells, as well as selected tissues from Syrian golden hamsters, were used. To verify the results, Western blot and Northern slot-blot analyses were performed.

RESULTS

Pancreatic cancer cells, in vitro and in vivo, showed a remarkable heterogeneity in the immunostaining of ErbB2, ranging from very faintly to strongly stained. On the other hand, in both humans and hamsters, a consistently strong immunostaining was found in the Langerhans' islets, in the ganglia of intrapancreatic and extrapancreatic nerves, as well as in the CNS, spinal cord and adrenal gland.

CONCLUSIONS

ErbB2 appears to play an important role in neuroendocrine tissues and is probably involved in the development and functional regulation of these cells. The concomitant expression of these factors and islet cell hormones very likely results in the activation of multiple growth-promoting pathways in pancreatic cancer and its aggressive behavior.

Application of a Gene Vaccine Targeting HER-2/Neu in Immunocontraception

HER-2/neu was widely used as a target for tumor prevention and therapy because of its overexpression in many tumors. However, it also plays an important role in proliferation of endometrium, embryo implantation, and development. Here, HER-2/neu was used in immunocontraception. A gene vaccine encoding the extracellular domain of human HER-2/neu was constructed. After immunization, it especially elicited both humoral and cellular responses in mice. Embryo implantation was interfered by intravenous and intraluminal injection of anti-HER-2/neu serum or lymphocytes. Lower fertility was induced after vaccination when compared with the control groups, while injuries to the uterus and ovary were not observed. Our results suggested a new and impactful target for contraceptive vaccines development.

Expression of e-cadherin in high-risk breast cancer

PURPOSE

E-cadherin expression is diverse, and differences in patient characteristics may produce variability in expression. Whereas some studies have indicated that downregulation of e-cadherin, associated with loss of cellular adhesiveness, was correlative with poor prognosis and metastasis, other studies have failed to confirm this. The present study uses a highly homogenous population of patients at high-risk for breast cancer, on the basis of ethnic and socio-economic status, to examine the relationship between e-cadherin and other prognostic markers in breast cancer.

METHODS

Immunohistochemical staining was undertaken for estrogen (ER) and progesterone (PR) receptors, epidermal growth factor receptor 2 (Her-2), p53, vascular endothelial factor (VEGF), and hypoxia inducible factor 1alpha (HIF-1alpha) and the levels of these markers was compared to e-cadherin expression in a high-risk African-American patient population.

RESULTS

E-cadherin expression persisted into the later stagers of the disease, and was strongly associated with Her-2 and HIF-1alpha expression, but not p53, ER/PR or VEGF.

CONCLUSIONS

In contrast to other studies on heterogeneous populations, e-cadherin is preserved in aggressive tumors in this high-risk population. The ethnic and socio-economic risk stratification needs to be accounted for in studies correlating markers and prognosis.

Relevance of breast cancer cell lines as models for breast tumours: an update

The number of available breast cancer cell (BCC) lines is small, and only a very few of them have been extensively studied. Whether they are representative of the tumours from which they originated remains a matter of debate. Whether their diversity mirrors the well-known inter-tumoural heterogeneity is another essential question. While numerous similarities have long been found between cell lines and tumours, recent technical advances, including the use of micro-arrays and comparative genetic analysis, have brought new data to the discussion. This paper presents most of the BCC lines that have been described in some detail to date. It evaluates the accuracy of the few of them widely used (MCF-7, T-47D, BT-474, SK-BR-3, MDA-MB-231, Hs578T) as tumour models. It is concluded that BCC lines are likely to reflect, to a large extent, the features of cancer cells in vivo. The importance of oestrogen receptor-alpha (gene ESR1 ) and Her-2/ neu ( ERBB2 ) as classifiers for cell lines and tumours is underlined. The recourse to a larger set of cell lines is suggested since the exact origin of some of the widely used lines remains ambiguous. Investigations on additional specific lines are expected to improve our knowledge of BCC and of the dialogue that these maintain with their surrounding normal cells in vivo.

Roles of the transcription factors snail and slug during mammary morphogenesis and breast carcinoma progression

The zinc-finger transcription factors Snail and Slug are involved in different processes controlling cell differentiation and apoptosis. They also appear to be involved in tumor progression. Their putative involvement in mammary gland development has not been specifically examined so far. Slug is expressed at a significant level in normal breast, and indirect evidence suggests it could be implicated in tubulogenesis. As an antiapoptotic agent, it could also protect epithelial cells from death during ductal lumen formation and during breast involution. In breast carcinomas, Snail transcription factors have been linked to tumor progression and invasiveness. Possible mechanisms include repression of the E-cadherin gene by Snail or Slug. However, it is not clear how this transcriptional activity is implicated in vivo. Other possible mechanisms involve maintenance of a plastic phenotype by Slug that could participate in local invasion of ductal carcinomas, and interference with apoptotic pathways that could contribute to global tumor growth and radioresistance. These processes probably also involve interactions with estrogen, EGF, or c-kit pathways.

E6/E7 proteins of HPV type 16 and ErbB-2 cooperate to induce neoplastic transformation of primary normal oral epithelial cells

Head and neck squamous cell carcinomas (HNSCC) are characterized by a marked propensity for local invasion and spread to cervical lymph nodes, with distant metastases developing in 30-40% of cases. HPV-16 is an important risk factor for HNSCC. How HPV enhances susceptibility to HNSCC is not fully understood, but seems to involve cofactors. In this study, we examined the effect of the cooperation between HPV-16 and the tyrosine kinase receptor ErbB-2 on E-cadherin/catenin complex patterns and neoplastic transformation of human normal oral epithelial (NOE) cells. We report that overexpression of ErbB-2 or E6/E7 alone does not affect E-cadherin/catenin complex patterns nor does it induce cell transformation of NOE cells. In contrast, coexpression of E6/E7 and ErbB-2 downregulates E-cadherin and catenin expression. This is accompanied by cytoplasmic localization of E-cadherin, as well as nuclear translocation of alpha, beta, and gamma-catenins. Furthermore, we demonstrate that E6/E7 cooperate with overexpressed ErbB-2 to induce tumor formation in nude mice and to upregulate cyclin D1 and c-myc expression. Our data suggest that E6/E7 cooperate with ErbB-2 in head and neck carcinogenesis, at least in part, via the conversion of beta-catenin from a cell adhesion to a nuclear function, that is, to act as a potential transcriptional regulator. This conversion leads to the upregulation of cyclin D1, c-myc and other oncoproteins necessary for alteration of the E-cadherin/catenin complex and cell transformation of NOE cells.

Cadherins in cancer

The presence of a functional E-cadherin/catenin cell-cell adhesion complex is a prerequisite for normal development and maintenance of epithelial structures in the mammalian body. This implies that the acquisition of molecular abnormalities that disturb the expression or function of this complex is related to the development and progression of most, if not all, epithelial cell-derived tumors, i.e. carcinomas. E-cadherin downregulation is indeed correlated with malignancy parameters such as tumor progression, loss of differentiation, invasion and metastasis, and hence poor prognosis. Moreover, E-cadherin has been shown to be a potent invasion suppressor as well as a tumor suppressor. Disturbed expression profiles of the E-cadherin/catenin complex have been demonstrated in histological sections of many human tumor types. In different kinds of carcinomas, biallelic downregulation of the E-cadherin gene, resulting in tumor-restricted decrease or even complete loss of E-cadherin expression, appears to be caused by a variety of inactivation mechanisms. Gene deletion due to loss of heterozygosity of the CDH1 locus on 16q22.1 frequently occurs in many carcinoma types. However, somatic inactivating mutations resulting in aberrant E-cadherin expression by loss of both wild-type alleles is rare and restricted to only a few cancer types. A majority of carcinomas thus seems to show deregulated E-cadherin expression by other mechanisms. The present evidence proposes transcriptional repression as a powerful and recurrent molecular mechanism for silencing E-cadherin expression. The predominant mechanisms emerging in most carcinomas are hypermethylation of the E-cadherin promoter and expression of transrepressor molecules such as SIP1, Snail, and Slug that bind sequence elements in the proximal E-cadherin promoter. Interestingly, complex differential expression of other cadherins seems to be associated with loss of E-cadherin and to reinforce effects of this loss on tumor progression. Multiple agents can upregulate and stabilize the E-cadherin/catenin complex. Especially for those tumors with transcriptional and thus reversible downregulation of E-cadherin expression, these drug agents offer important therapeutic opportunities.

Bcl-2 expression decreases cadherin-mediated cell-cell adhesion

Bcl-2, a member of the apoptosis-regulating family of proteins confers a survival advantage on cells by inhibiting apoptosis. Bcl-2 expression is estrogen-responsive and high in various tumors. Overexpression of Bcl-2 has been associated with the loss of contact inhibition, unregulated growth and foci formation in culture. In this study, we have examined the effects of bcl-2 overexpression and expression on cell-cell adhesion in MCF-7 and MDCK epithelial cell lines respectively. Overexpression of Bcl-2 in estrogen receptor-positive MCF-7 mammary carcinoma cells led to decreased cell surface E-cadherin and the disruption of junctional complexes concurrent with intracellular redistribution of their components. Particularly noticeable, was the partial nuclear localization of the tight junction-associated protein ZO-1 which coincided with upregulation of ErbB2. The expression of this EGF co-receptor is regulated by the ZO-1-associated transcription factor ZONAB. Growth in estrogen-depleted media led to downregulation of Bcl-2 expression and upregulation and membrane localization of all junctional proteins. Similar disruption in junctions, accompanied by decreased transepithelial resistance, was observed when Bcl-2 was expressed in MDCK cells. These results strongly suggest that Bcl-2 expression decreases the level of functional E-cadherin thereby interfering with junction formation. The inhibition of junction formation decreases cell-cell adhesion leading to the loss of contact inhibition, which, in vivo, can lead to unregulated growth and tumorigenesis.

Epidermal growth factor family of receptors in preneoplasia and lung cancer: perspectives for targeted therapies

The Erb-B family of receptors plays an important role in lung carcinogenesis and tumor development, and EGFR and HER2 are highly expressed in bronchial preneoplasia. In invasive tumors, EGFR are expressed in 50-90%, and mostly in squamous cell carcinomas, but also in adenocarcinomas and large cell carcinomas, while HER2 is less frequently expressed (20-30%) and mostly expressed in adenocarcinomas. Bronchioloalveolar cell carcinomas may present a distinct EGFR profile compared to the other NSCLCs and evidence and consequences are discussed. The genetic mechanisms responsible for overexpression of EGFR and HER2 proteins might be numerous, including gene dosage (overrepresentation or amplification) as well as translational and post-translational mechanisms. However, for EGFR and HER2 there is a positive correlation between gene copy numbers and level of protein expression demonstrated by fluorescence in situ hybridization analysis and immunochemistry. Gene amplification for EGFR and HER2 is demonstrated in only 5-10% of the tumors. The treatment status and therapeutic limitation with trastuzumab (Herceptin) in lung cancer compared to breast cancer is discussed.

Heregulin and retinoids synergistically induce branching morphogenesis of breast cancer cells cultivated in 3D collagen gels

C-erbB and retinoid receptor signaling control mammary epithelial cell proliferation, differentiation, and morphology. Here, we examined the morphogenetic activities of c-erbB specific ligands such as heregulin and of retinoids on non-malignant (primary, MTSV1-7) and malignant (T47D, SKBR-3) human mammary epithelial cells (HMEC) cultivated in 3D collagen type I gels. These cells are positive for both c-erbB and retinoid receptors. Non-malignant primary HMEC spontaneously formed branched structures in collagen, whereas SV40 large T antigen-immortalized non-tumorigenic MTSV1-7 spontaneously formed balls and required heregulin or retinoid X receptor alpha-selective retinoid Ro 25-7386 for branching, which was further stimulated by combination of both types of agents. In malignant cells, heregulin alone induced ball formation and cooperated either with Ro 25-7386 (T47D) or with retinoic acid receptor alpha-selective AM580 (SKBR-3) for branching morphogenesis, which was accompanied by changes in the subcellular distribution of alpha(2)beta(1)-integrin and E-cadherin, and by down-regulation of c-erbB-2, -3, or -4. Heregulin and/or retinoids correspondingly increased the integrin-dependent adhesion of malignant cells to type I collagen. Our data demonstrate cooperative signaling of c-erbB and retinoid receptor pathways at the levels of morphogenesis and immunophenotypic differentiation.

Episomally mediated overexpression of wild-type erbB-2 transforms MCF-10A breast epithelial cells

MCF-10A are human non-transformed, EGF and insulin dependent breast epithelial cells. The cells were transfected with an episomal pCEP4 vector library containing cDNA from SKBR3 breast carcinoma cells, and selected in media without EGF. After two cycles of expression cloning, morphologically transformed cells appeared. Extracted episomes contained a high proportion of erbB-2 cDNA with wild-type transmembrane domains. Transfection of MCF-10A with individual erbB-2 containing episomes induced significant foci formation in low serum (0.1%) without EGF. MCF-10A sublines expanded from these foci contained a high number of erbB-2 gene copies, highly expressed erbB-2, and lost E-cadherin expression. These results show that if wild-type erbB-2 is sufficiently overexpressed, erbB-2 alone can cause EGF independent transformation of these nonmalignant breast cells. This expression system may be useful for expression cloning in MCF-10A cells, and simulating the effects of high erbB-2 gene amplification in breast epithelial cells.

Melanoma development and progression: a conspiracy between tumor and host

While a genome-centric paradigm in human cancer development was useful for the understanding of some malignancies such as leukemias, causative molecular defects intrinsic to melanocytes have not been defined in the majority of human melanomas. Recent work, however, has shown that regulatory signals governing melanocytic cell growth and differentiation may originate from the surrounding host cells either directly through physical contact or indirectly through soluble factors and extracellular matrix molecules. In this review, we present experimental systems useful for dissecting melanoma-host interactions and highlight evidence that the tumor microenvironment contributes to the oncogenic process. Thus, melanomagenesis is not merely an act of a single outlaw but a conspiracy orchestrated by multiple partners in the neighborhood who come into play in a precise spatiotemporal order. Defining intercellular molecular dialogues in human skin promises to provide key information for the development of novel treatment strategies that target the functional unit of stroma and tumor.

Differential gene expression patterns in HER2/neu-positive and -negative breast cancer cell lines and tissues

Overexpression of the oncogene HER2/neu (c-erbB-2) occurs in up to 30% of breast cancers and is correlated with reduced survival, especially in node-positive disease. The aim of this study was to identify genes associated with the aggressive phenotype of HER2/neu-positive breast cancer cells using cDNA microarrays. RNA was extracted from three HER2/neu-positive and three HER2/neu-negative breast cancer cell lines. Pooled RNA was hybridized in duplicate to the breast specific microarray filters from Research Genetics containing 5184 unique cDNAs. Subsequently, a similar comparison was performed for pooled RNAs from 10 node-positive, ER-positive invasive ductal carcinomas, half of which were HER2/neu overexpressers. In HER2/neu overexpressing breast cancer cell lines, 90 (1.7%) genes were up-regulated and 46 (0.9%) were down-regulated, compared to cell lines with low HER2/neu protein levels. In contrast, in HER2/neu overexpressing primary breast cancers, more genes were down-regulated (N = 132, 2.5%) than up-regulated (N = 19, 0.4%). Many of the differentially expressed genes have previously not been known to play a role in human neoplasia, and some of them may represent novel tumor suppressor or oncogenes. No genes were up-regulated, and only a small number of genes were down-regulated both in cell lines and in carcinomas with high HER2/neu protein levels. These included transforming acidic coiled-coil containing protein 1, glycogen phosphorylase BB, complement 1q and one EST. The differential expression of select genes was confirmed by Northern blotting (trefoil factor 3) or by immunocytochemistry (glycogen phosphorylase BB, vimentin, KAI1). In an extended validation study, 18 of 41 ER-negative, but none of 46 ER-positive, breast carcinomas were found to express vimentin, and all but one of the vimentin-positive tumors were confined to the HER2/neu-negative subgroup (P = 0.0019). Our findings support an important role of the mammary stroma in determining the clinical breast cancer phenotype.

Non-small cell lung cancer clinical trials with trastuzumab: their foundation and preliminary results

The overexpression of HER2, a transmembrane glycoprotein tyrosine kinase, has been implicated in mitogenesis, cell survival, invasion and angiogenesis. Preclinical evidence suggests that HER2 overexpression contributes to tumor progression in non-small cell lung cancer (NSCLC) and retrospective clinical correlative studies show that it is probably associated with poor clinical outcome. Trastuzumab (Herceptin, Genentech Inc., South San Francisco, CA) is a recombinant humanized monoclonal antibody that targets HER2 and is currently approved for use in the treatment of patients with HER2-overexpressing metastatic breast cancer. Two primary mechanisms proposed for the activity of trastuzumab are downregulation of HER2 and induction of antibody-dependent cell-mediated cytotoxicity. Evidence from preclinical studies of trastuzumab in NSCLC and other cell lines, the presence of HER2 overexpression in NSCLC clinical specimens and the clinical benefit derived from trastuzumab in phase II and III metastatic breast cancer trials have led to the development of clinical trials of trastuzumab in NSCLC. Phase II studies of trastuzumab in patients with stage IIIB or IV NSCLC are being conducted to test the efficacy of trastuzumab as a single agent or in combination with chemotherapy. Preliminary results show combinations of chemotherapy plus trastuzumab are well tolerated, with encouraging response rates of 21-40%. A randomized phase II trial of chemotherapy with or without trastuzumab showed promise in a small subgroup of patients with 3+ HER2 overexpression by immunohistochemistry or HER2 DNA amplification by fluorescence in situ hybridization. Taken together, these data indicate that trastuzumab warrants further investigation in a clinical study in selected patients with NSCLC.

The E-cadherin cell-cell adhesion complex and lung cancer invasion, metastasis, and prognosis

BACKGROUND

Lung cancer is the most common cause of cancer deaths in the western world. Progress in treatment results has been limited, and the prognosis is poor with a 5-year survival less than 15%. Based on new developments in molecular biology, our knowledge about lung carcinogenesis and mechanisms for invasion and metastasis has expanded and may in the future lead to more specific targeted therapies and better prognosis. The E-cadherin-catenin complex is critical for intercellular adhesiveness and maintenance of normal and malignant tissue architecture. Reduced expression of this complex in malignant disease is associated with tumour invasion, metastasis, and unfavorable prognosis.

METHODS

This review is based on search in the Medline database from 1991 to 2001. We have reviewed the relevance of the E-cadherin-catenin adhesion complex in malignancy in general and lung cancer in particular. Furthermore, its role as target for specific therapy is discussed.

RESULTS

Available data indicate that alterations of proteins involved in the E-cadherin-catenin complex are early incidents in cancer development. Reduced or altered expression of one or more of the components in this complex is associated with extended invasive and progressive behavior of cancer cells. Consistently, the E-cadherin-catenin complex appears to be increasingly delicate with regard to cancer prognosis. beta-Catenin, one of the components of the adhesion complex, also plays a significant role in cell signal transduction, gene activation, apoptosis inhibition, and increased cellular proliferation and migration.

CONCLUSION

Inactivation of the E-cadherin-catenin adhesion complex, induced by genetic and epigenetic events, plays a significant role in multistage carcinogenesis, and seems to be associated with dedifferentiation, local invasion, regional metastasis, and reduced survival in lung cancer.

Expression of E-cadherin catenin and C-erbB-2 gene products in invasive ductal-type breast carcinomas

Special attention has focused on E-cadherin and the invasiveness of breast carcinoma because E-cadherin was suggested to be the major cell adhesion molecule in the mammary gland. In the cytoplasm, E-cadherin is linked to beta-catenin and alpha-catenin which mediate the connection of the cytoskeleton. In addition, c-erbB-2 oncoprotein causes disruption of this cell adhesion system through beta-catenin phosphorylation. We investigated the expression of E-cadherin, alpha-catenin and c-erbB-2 gene products in 66 invasive ductal carcinomas by immuno-histochemistry to examine the relation between the E-cadherin mediated cell adhesion system and histological subtypes used in Japan as well as histological grading. The series included 21 papillotubular carcinomas, 16 solid-tubular carcinomas and 29 scirrhous carcinoma. There were 33 cases of grade I, 20 cases of grade II and 13 cases of grade III. We defined P&P&N as E-cadherin positive and alpha-catenin positive and c-erbB-2 negative cases to evaluate the preservation of the E-cadherin mediated cell adhesion system. There were only 13 cases (19.7%) of P&P&N in total. As for the frequency of E-cadherin/alpha-catenin/c-erbB-2 expression and P&P&N, no significant difference between histological subtypes was found. However, those in the grade I group tended to be higher than in the other two grade groups. Regarding the rates of alpha-catenin positive cases and P&P&N cases, there were significant differences between the grade I group and a combination group consisting of the grade II and grade III groups. These results suggest that the E-cadherin-mediated cell adhesion system is frequently lost in invasive ductal-type breast cancers by random loss of E-cadherin/catenins or c-erbB-2 overexpression, and that the preservation of this system correlates with well differentiated morphological features.

Real-time quantitative analysis of E-cadherin expression in ret/PTC-1-activated thyroid neoplasms

Papillary thyroid carcinoma (PTC), the most common variety of thyroid cancer, is found in a variety of morphologic variants, usually grows slowly, and is clinically indolent, although rare, aggressive forms, with local invasion or distant metastases, occur. Our group has previously demonstrated an association between Hashimoto thyroiditis and ret/PTC-1 activation, and have hypothesised that c-ret activation might be implicated in immune reaction to thyroid epithelium. The objective of this study was to examine expression of the cellular adhesion molecule, E-cadherin, in various thyroid tumor types and Hashimoto thyroiditis in the context of ret/PTC-1 positivity by using laser capture microdissection and TaqMan reverse transcription-polymerase chain reaction (RT-PCR). Variable down-regulation of E-cadherin among carcinomas was demonstrated, with anaplastic carcinomas showing little or no expression. Follicular thyroid carcinomas consistently had significantly decreased E-cadherin expression compared with papillary thyroid carcinomas. The ret/PTC-1-positive papillary thyroid carcinoma (PTCret+) and Hashimoto thyroiditis cases had consistently lower E-cadherin expression levels than the corresponding ret/PTC-1-negative papillary carcinomas (PTCret-), suggesting not only an association between ret activation and the loss of cellular adhesion but also, more significantly, an association between papillary thyroid carcinoma and Hashimoto thyroiditis.

The role of c-erbB-2/HER2/neu in breast cancer progression and metastasis

Gene amplification and/or overexpression of the c-erbB-2/HER2/neu tyrosine kinase are linked with poor prognosis in breast cancer. This is manifest in shorter disease-free intervals, increased risk of metastasis, and resistance to many types of therapy. The molecular mechanisms and signaling circuitry underlying these phenomena are now being elucidated. c-erbB-2, although having no known soluble ligand, is transactivated by heterodimerization with other family members (EGFR, c-erbB-3, c-erbB-4). Receptor activation potentiates tumor cell motility, protease secretion and invasion, and also modulates cell cycle checkpoint function, DNA repair, and apoptotic responses. Since it is expressed at low levels in normal adult tissues, c-erbB-2 is an ideal target for therapy. There is reason for optimism that agents targeting c-erbB-2 signaling will have profound and selective effects in breast cancer, either as single agents or more likely in combination with other therapeutic agents, to enhance their potency.

ErbB2, but not ErbB1, reinitiates proliferation and induces luminal repopulation in epithelial acini

Both ErbB1 and ErbB2 are overexpressed or amplified in breast tumours. To examine the effects of activating ErbB receptors in a context that mimics polarized epithelial cells in vivo, we activated ErbB1 and ErbB2 homodimers in preformed, growth-arrested mammary acini cultured in three-dimensional basement membrane gels. Activation of ErbB2, but not that of ErbB1, led to a reinitiation of cell proliferation and altered the properties of mammary acinar structures. These altered structures share several properties with early-stage tumours, including a loss of proliferative suppression, an absence of lumen, retention of the basement membrane and a lack of invasive properties. ErbB2 activation also disrupted tight junctions and the cell polarity of polarized epithelia, whereas ErbB1 activation did not have any effect. Our results indicate that ErbB receptors differ in their ability to induce early stages of mammary carcinogenesis in vitro and this three-dimensional model system can reveal biological activities of oncogenes that cannot be examined in vitro in standard transformation assays.

Expression and Tyrosine Phosphorylation of E-Cadherin, β- and γ-Catenin, and Epidermal Growth Factor Receptor in Cervical Cancer Cells

OBJECTIVES

The cadherin/catenin adhesion complex is fundamentally involved in epithelial cancer invasion and metastasis. Much evidence suggesting that epidermal growth factor (EGF) induced the scattering and invasion of cancer cells, probably by affecting E-cadherin function, has been reported. The present study aimed to confirm the hypothesis that EGF/epidermal growth factor receptor (EGFR) was related with the E-cadherin adhesion system in cervical cancer cells and that EGF might induce tyrosine phosphorylation of beta- and gamma-catenin.

METHODS

Cervical cancer cells were treated for different time durations with 30 ng/ml of EGF. Alteration of the cell morphology was examined by light microscopy and the expression of E-cadherin, beta-catenin, gamma-catenin, EGFR, and activated EGFR was assayed using Western blotting. Tyrosine phosphorylation of beta- and gamma-catenin was also examined using immunoprecipitation.

RESULTS

E-cadherin and EGFR were expressed in CaSki, HT-3, and ME-180 cell lines, which showed epithelial contact growth. The expression of E-cadherin and beta- and gamma-catenin did not change after treatment with EGF. The expression of EGFR decreased and activated EGFR expression increased in 30 min and then decreased subsequently. The simultaneous expression of activated EGFR and tyrosine phosphorylation of beta- and gamma-catenin was found.

CONCLUSIONS

EGF-induced scattering of the E-cadherin-positive cervical cancer cells might be the result of tyrosine phosphorylation of the beta- and gamma-catenin. Phosphorylation of the beta- and gamma-catenin may hamper the adhesive function of the E-cadherin-catenin complex.

Tob-mediated cross-talk between MARCKS phosphorylation and ErbB-2 activation

The biochemical path for the activation of ErbB-2 by PKC activator was investigated in MDA-MB-231 human breast cancer cells. We found that PMA-induced phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS) increased its binding with Tob that exerts an anti-proliferative effect through the binding with ErbB-2. The phosphorylation site domain (PSD) of MARCKS was relevant to its interaction with Tob. Decreased binding of Tob with ErbB-2 and subsequent activation of ErbB-2 were observed in MDA-MB-231 cells in response to PMA treatment. The present study proposes that MARCKS phosphorylation by PKC removes Tob from ErbB-2 by increasing its binding affinity with Tob, and thereby activates the ErbB-2 mediated signal transduction.

Regulation of MUC1 expression in human mammary cell lines by the c-ErbB2 and ras signaling pathways

The MUC1 protein is a highly O-glycosylated transmembrane molecule that is expressed at the luminal surface of most glandular epithelial cells and is upregulated in carcinomas. Here, we report the effect of the activation of the c-ErbB2 --> Ras pathway on the expression of the MUC1 gene in the nontumorigenic mammary cell lines MTSV1-7 and HB2 and in the malignant cell lines T47D and ZR75. Endogenous levels of MUC1 mRNA and protein in HB2 clones permanently overexpressing c-ErbB2 or V12-H-Ras were markedly reduced compared with levels in the parental cell lines. Furthermore, in transient transfection assays, the transcription of a CAT reporter construct driven by the MUC1 promoter was inhibited when cotransfected with a c-ErbB2 or a V12-H-ras expressing vector. Transient transfections using mutant forms of the ras oncogene, and the inhibitor chemical wortmannin, indicated that the pathway activated by c-ErbB2 proceeds via activation of Ras and that the Raf and phosphoinositide 3-kinase pathways are involved. Finally, cotransfection assays using a reporter gene driven by the MUC1 promoter carrying abolishing mutations in some of the cis-acting elements showed that a GC box at -99/-91 is crucial for responsiveness to c-ErbB2 inhibition of transcription.

Distinct tyrosine autophosphorylation sites mediate induction of epithelial mesenchymal like transition by an activated ErbB-2/Neu receptor

Tight control of cell proliferation and morphogenesis is required to ensure normal tissue patterning and prevent cancer formation. Overexpression of the ErbB-2/Neu receptor tyrosine kinase is associated with increased progression in human breast cancer, yet in breast explant cultures, the ErbB-2/Neu receptor contributes to alveolar differentiation. To examine the consequence of deregulated ErbB-2/Neu activation on epithelial morphogenesis, we have expressed a constitutively activated mutant of ErbB-2/Neu in a Madin-Darby canine kidney (MDCK) epithelial cell model. Using two-dimensional cultures we demonstrate that activated ErbB-2/Neu induces breakdown of cell-cell junctions, increased cell motility and dispersal of epithelial colonies. This correlates with reorganization of the actin cytoskeleton and focal adhesions and loss of insoluble cell-cell junction complexes involving E-cadherin. Interestingly, a constitutively activated ErbB-2/Neu receptor promotes an invasive morphogenic program in MDCK cells in a three-dimensional matrix. We show that two tyrosines in the carboxy-terminal tail of ErbB-2/Neu, involved in the phosphorylation of the Shc adapter protein, are each sufficient to promote epithelial-mesenchymal like transition and enhanced cell motility in two-dimensional culture and cell invasion rather than a morphogenic response in matrix culture. This provides a model system to investigate ErbB-2/Neu induced signaling pathways required for epithelial cell dispersal and invasion versus morphogenesis.