Involvement of nuclear NHERF1 in colorectal cancer progression

Nuclear expression of NHERF1/EBP50 in Clear Cell Renal Cell Carcinoma

The Na/H exchange regulatory factor 1 or Ezrin-radixin-moesin-binding phosphoprotein 50 (NHERF1/EBP50) is an adaptor protein implicated in the stabilization of molecular complexes linking extracellular signals with the cytoskeleton machinery. NHERF1 expression at the cell cortex is associated with the maintenance of adherent junction integrity in polarized epithelia. The role of NHERF1 in cancer depends on its localization within the cell, acting, in most cases, as a tumor suppressor when localized at the cell membrane, and as an oncogene, when expressed in the cytoplasm or the nucleus of cancer cells. The distribution of NHERF1 in renal cell carcinoma (RCC) has not been yet investigated. In this study, NHERF1 expression was examined by immunohistochemistry in papillary and clear cell RCC. We observed membranous staining in papillary RCC, whereas NHERF1 expression was nuclear and membranous in clear cell RCC. In comparison, NHERF1 immunohistochemistry in clear cell carcinomas of the ovary showed mainly nuclear staining. Our finding of the specific NHERF1 nuclear expression in clear cell carcinomas may help to elucidate the molecular changes that regulate its nuclear accumulation and to better understand its role in this cell compartment.

Polarity scaffolds signaling in epithelial cell permeability

As an integral part of the innate immune system, the epithelial membrane is exposed to an array of insults that may trigger an immune response. One of the immune system's main functions is to regulate the level of communications between the mucosa and the lumen of various tissues. While it is clear that inhaled or ingested substances, or microorganisms may induce changes that affect the epithelial barrier in various ways, the proteins involved in the signaling cascades and physiological events leading to the regulation and maintenance of the barrier are not always well characterized. We review here some of the signaling components involved in regulating the barrier's paracellular permeability, and their potential effects on the activation of an immune response. While an effective immune response must be launched against pathogenic insults, tolerance must also be maintained for non-pathogenic antigens such as those in the commensal flora or for endogenous metabolites. Along with other members of the innate and adaptive immunity, the endocannabinoid system also plays an instrumental role in maintaining the balance between inflammation and tolerance. We discuss the potential effects of endo- and phytocannabinoids on epithelial permeability and how the dysregulation of this system could be involved in diseases and targeted for therapy.

A Critical Role for Na+/H+ Exchanger Regulatory Factor 1 in Modulating FcεRI-Mediated Mast Cell Activation

Mast cells are tissue-resident immune cells that play pivotal roles in initiating and amplifying allergic/anaphylactic reactions in humans. Their activation occurs via multiple mechanisms, which include cross-linking of the IgE-bound, high-affinity IgE receptors (FcεRI) by allergens or Ags and the binding of anaphylatoxins such as C3a to its receptor, C3aR. We have previously demonstrated that the Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1) promotes C3aR functions in human mast cells. In the current study, we show that NHERF1 regulates mast cell response following FcεRI stimulation. Specifically, intracellular Ca²⁺ mobilization, activation of the MAPKs (ERK1/2 and P38), and production of cytokines (IL-13 and IL-6) following exposure to IgE/Ag were significantly reduced in mast cells from NHERF1^+/‒ mice. In agreement with our in vitro data, mast cell-mediated passive cutaneous anaphylaxis and passive systemic anaphylaxis were reduced in NHERF1^+/‒ mice and mast cell-deficient Kit^W-sh/W-sh mice engrafted with NHERF1^+/‒ mast cells. Mechanistically, the levels of microRNAs (miRNAs) that regulate mast cell responses, miRNA 155-3p and miRNA 155-5p, were altered in mast cells from NHERF1^+/‒ mice. Moreover, NHERF1 rapidly localized to the nucleus of mast cells following FcεRI stimulation. In summary, our results suggest that the NHERF1 acts as an adapter molecule and promotes IgE/Ag-induced mast cell activation. Further elucidating the mechanisms through which NHERF1 modulates mast cell responses will lend insights into the development of new therapeutic strategies to target mast cells during anaphylaxis or other allergic diseases.

Alteration in the sensitivity to crizotinib by Na+/H+ exchanger regulatory factor 1 is dependent to its subcellular localization in ALK-positive lung cancers

Background

Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1) is an important scaffold protein participates in the modulation of a variety of intracellular signal pathways. NHERF1 was able to enhance the effects of chemo-drugs in breast and cervical cancer cells. Anaplastic lymphoma kinase (ALK) fusion mutations are validated molecules targeted therapy in lung cancers, where crizotinib can be used as the specific inhibitor to suppress tumor progression. However, due to the less frequent occurrence of ALK mutations and the complexity for factors to determine drug responses, the genes that could alter crizotinib sensitivity are unclear.

Methods

Both ALK-translocated and ALK-negative lung adenocarcinoma specimens in tissue sections were collected for immunohistochemistry. The possible mechanisms of NHERF1 and its role in the cell sensitivity to crizotinib were investigated using an ALK-positive and crizotinib-sensitive lung adenocarcinoma cell line H3122. Either a NHERF1 overexpression vector or agents for NHERF1 knockdown was used for crizotinib sensitivity measures, in association with cell viability and apoptosis assays.

Results

The expression level of NHERF1 in ALK-translocated NSCLC was significantly higher than that in other lung cancer tissues. NHERF1 expression in ALK positive lung cancer cells was regulated by ALK activities, and was in return able to alter the sensitivity to crizotinib. The function of NHERF1 to influence crizotinib sensitivity was depending on its subcellular distribution in cytosol instead of its nucleus localized form.

Conclusion

Ectopically overexpressed NHERF1 could be a functional protein for consideration to suppress lung cancers. The determination of NHERF1 levels in ALK positive NSCLC tissues might be useful to predict crizotinib resistance, especially by distinguishing cytosolic or nuclear localized NHERF1 for the overexpressed molecules.

Fluorescence Lifetime-Based Tumor Contrast Enhancement Using an EGFR Antibody-Labeled Near-Infrared Fluorophore

PURPOSE

Imaging techniques for highly specific detection of cancer cells in vivo can have applications ranging from preclinical drug discovery studies to clinical cancer diagnosis and surgical therapy. Although fluorescence imaging using cancer-targeted antibodies has shown promise, nonspecific probe accumulation in tissue results in significant background fluorescence, reducing detection sensitivity using traditional intensity-based continuous-wave (CW) fluorescence imaging. Here we demonstrate that fluorescence lifetime (FLT) imaging can provide significant tumor contrast enhancement over CW intensity in preclinical models of human breast cancer.

EXPERIMENTAL DESIGN

Mice bearing MDA-MB-231 tumors were injected with anti-EGFR antibody conjugated to the fluorescent dye IRDye 800CW (anti-EGFR-800). Time domain fluorescence imaging was performed in vivo and in situ up to 48 hours after dye injection.

RESULTS

Mice injected with anti-EGFR-800 showed a significantly longer FLT (0.7 ± 0.03 ns) compared with the FLT of nonspecific probe uptake in liver (0.63 ± 0.05 ns), providing a dramatic improvement in sensitivity and specificity compared with CW intensity. IgG antibody-conjugated IRDye 800CW did not show an increased FLT compared with normal tissue, suggesting that the FLT increase of anti-EGFR-800 in tumors was associated with receptor expression. Using serial surgery, we show that FLT allows the detection of smaller residual tumors in the surgical bed than possible using CW intensity.

CONCLUSIONS

Our data suggest that FLT can significantly enhance tumor contrast using fluorescently labeled antibodies, thereby accelerating the efficient clinical application of these probes for margin assessment in image-guided surgery and for highly specific detection of tumor receptors in vivo.

NHERF1 Between Promises and Hopes: Overview on Cancer and Prospective Openings

Na+/H+ exchanger regulatory factor 1 (NHERF1) is a scaffold protein, with two tandem PDZ domains and a carboxyl-terminal ezrin-binding (EB) region. This particular sticky structure is responsible for its interaction with different molecules to form multi-complexes that have a pivotal role in a lot of diseases. In particular, its involvement during carcinogenesis and cancer progression has been deeply analyzed in different tumors. The role of NHERF1 is not unique in cancer; its activity is connected to its subcellular localization. The literature data suggest that NHERF1 could be a new prognostic/predictive biomarker from breast cancer to hematological cancers. Furthermore, the high potential of this molecule as therapeutical target in different carcinomas is a new challenge for precision medicine. These evidences are part of a future view to improving patient clinical management, which should allow different tumor phenotypes to be treated with tailored therapies. This article reviews the biology of NHERF1, its engagement in different signal pathways and its involvement in different cancers, with a specific focus on breast cancer. It also considers NHERF1 potential role during inflammation related to most human cancers, designating new perspectives in the study of this "Janus-like" protein.

β-catenin knockdown promotes NHERF1-mediated survival of colorectal cancer cells: implications for a double-targeted therapy

Nuclear activated β-catenin plays a causative role in colorectal cancers (CRC) but remains an elusive therapeutic target. Using human CRC cells harboring different Wnt/β-catenin pathway mutations in APC/KRAS or β-catenin/KRAS genes, and both genetic and pharmacological knockdown approaches, we show that oncogenic β-catenin signaling negatively regulates the expression of NHERF1 (Na⁺/H⁺ exchanger 3 regulating factor 1), a PDZ-adaptor protein that is usually lost or downregulated in early dysplastic adenomas to exacerbate nuclear β-catenin activity. Chromatin immunoprecipitation (ChIP) assays demonstrated that β-catenin represses NHERF1 via TCF4 directly, while the association between TCF1 and the Nherf1 promoter increased upon β-catenin knockdown. To note, the occurrence of a cytostatic survival response in settings of single β-catenin-depleted CRC cells was abrogated by combining NHERF1 inhibition via small hairpin RNA (shRNA) or RS5517, a novel PDZ1-domain ligand of NHERF1 that prevented its ectopic nuclear entry. Mechanistically, dual NHERF1/β-catenin targeting promoted an autophagy-to-apoptosis switch consistent with the activation of Caspase-3, the cleavage of PARP and reduced levels of phospho-ERK1/2, Beclin-1, and Rab7 autophagic proteins compared with β-catenin knockdown alone. Collectively, our data unveil novel β-catenin/TCF-dependent mechanisms of CRC carcinogenesis, also offering preclinical proof of concept for combining β-catenin and NHERF1 pharmacological inhibitors as a mechanism-based strategy to augment apoptotic death of CRC cells refractory to current Wnt/β-catenin-targeted therapeutics.

NHERF1 regulates the progression of colorectal cancer through the interplay with VEGFR2 pathway

The oncogenic role of ectopic expression of Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1) was recently suggested in colorectal cancer, where it was implicated in playing a role in the tumor hypoxia microenvironment. Here we showed that a high level expression of NHERF1 was found in colorectal cancer tissues and that the expression of NHERF1 was positively correlated with VEGFR2 expression. The prognostic value of VEGFR2 expression in colorectal cancer relied on the expression of NHERF1. The up-regulation of NHERF1 induced by the exposure to hypoxia in colon cancer cells depended on the activation of VEGFR2 signaling. NHERF1 in turn inhibited the activation of VEGFR2 signaling which could be regulated by the interaction between NHERF1 and VEGFR2, resulting in the reduction of migration and invasion of colon cancer cells. These results suggest a dynamic interplay between NHERF1 and VEGFR2 signaling in colorectal cancer, which could explain the contribution of NHERF1 to the regulation of tumor cell responses to the hypoxia microenvironment.

β-catenin interaction with NHERF1 and RASSF1A methylation in metastatic colorectal cancer patients

There is an increasing need to identify new biomarkers in colorectal cancer (CRC) to further characterize this malignancy. β-catenin plays a central role in the Wnt signaling pathway. It also binds Na⁺/H⁺ exchanger regulating factor 1 (NHERF1) and interacts with the RAS-association domain family 1, isoform A (RASSF1A), but the mechanisms of this possible crosstalk are still not fully understood. In this study, we analyzed for the first time the different subcellular expression of β-catenin, NHERF1, and RASSF1A and their relationships with RASSF1A methylation in the progression of CRC. We assessed immunohistochemical expression and RASSF1A methylation in 51 patients with stage IV colorectal cancer. Biomarker expression analysis was carried out considering the tumor-adjacent normal tissue, the primary tumor, and the paired liver metastases. Regarding the tumor compartment, it was found that cytoplasmic β-catenin expression was positively correlated to membranous (r = 0.3002, p = 0.0323) and nuclear NHERF1 (r = 0.293, p = 0.0368). In the liver metastases, instead, we found a positive correlation of cytoplasmic and nuclear β-catenin expression with RASSF1A methylation (r = 0.4019, p = 0.0068 and r = 0.3194, p = 0.0345, respectively).

In conclusion, our results showed that β-catenin was the crucial protagonist in metastatic CRC through different effector proteins involved in this developing process. In tumor tissues, β-catenin was predominantly associated with NHERF1 in a dynamic context, while interestingly in liver metastases, we noted an increase of its oncogenic function through RASSF1A inactivation.

The cellular distribution of Na+/H+ exchanger regulatory factor 1 is determined by the PDZ-I domain and regulates the malignant progression of breast cancer

The oncogenic role of ectopic expression of Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1) was recently suggested. Here, we show that NHERF1 was upregulated in high grades compared with low grades. Increased NHERF1 expression was correlated with poor prognosis and poor survival. NHERF1 expression was higher in the nucleus of cancer cells than in contiguous non- mammary epithelial cells. A novel mutation, namely NHERF1 Y24S, was identified in human breast cancer tissues and shown to correspond to a conserved residue in the PDZ-I domain of NHERF1. Truncation and mutation of the PDZ-I domain of NHERF1 increased the nuclear distribution of the NHERF1 protein, and this redistribution was associated with the malignant phenotype of breast cancer cells, including growth, migration, and adhesion. The present results suggest a role for NHERF1 in the progression of breast cancer mediated by the nuclear distribution of the NHERF1 protein, as determined by the truncation or key site mutation of the PDZ-I domain.

Hierarchical clustering analysis identifies metastatic colorectal cancers patients with more aggressive phenotype

A large percentage of metastatic colorectal cancer (mCRC) patients presents metastasis at the time of diagnosis. In the last years, great efforts have been made in the treatment of these patients with the identification of different phenotypes playing a key role in the definition of new systemic therapies. Unsupervised hierarchical clustering analysis (HCA) was performed considering the clinicopathological characteristics of 51 mCRCs. Using immunohistochemistry on tissue microarrays, we assessed the expression of β-catenin, NHERF1, RASSF1A, TWIST1, HIF-1α proteins in tumors and paired liver metastases. We also analyzed RASSF1A methylation status on the samples of the same patients. HCA distinguished Group 1 and Group 2 characterized by different clinicopathological features. Group 1 was characterized by higher number of positive lymph nodes (p=0.0139), poorly differentiated grade (p<0.0001) and high extent of tumor spread (p=0.0053) showing a more aggressive phenotype compared to Group 2. In both Groups, we found a common "basal" condition with a higher level of nuclear TWIST1 (p<0.0001 and cytoplasmic β-catenin (p<0.0001) in tumors than in paired liver metastases. Furthermore, the Group 1 was also characterized by RASSF1A hypermethylation (p<0.0001) and nuclear HIF-1α overexpression (p=0.0354) in paired liver metastases than in tumors. In conclusion, HCA identifies mCRC patients with a more aggressive phenotype. Moroever, our results support the important contribution to the progression of the disease of RASSF1A methylation and the oncogenic role of HIF-1α in these patients. These evidences, should provide relevant information concerning the biology of this tumor and, as a consequence, potential new systemic therapeutic approaches.

Role of the PDZ-scaffold protein NHERF1/EBP50 in cancer biology: from signaling regulation to clinical relevance

The transmission of cellular information requires fine and subtle regulation of proteins that need to interact in a coordinated and specific way to form efficient signaling networks. The spatial and temporal coordination relies on scaffold proteins. Thanks to protein interaction domains such as PDZ domains, scaffold proteins organize multiprotein complexes enabling the proper transmission of cellular information through intracellular networks. NHERF1/EBP50 is a PDZ-scaffold protein that was initially identified as an organizer and regulator of transporters and channels at the apical side of epithelia through actin-binding ezrin-moesin-radixin proteins. Since, NHERF1/EBP50 has emerged as a major regulator of cancer signaling network by assembling cancer-related proteins. The PDZ-scaffold EBP50 carries either anti-tumor or pro-tumor functions, two antinomic functions dictated by EBP50 expression or subcellular localization. The dual function of NHERF1/EBP50 encompasses the regulation of several major signaling pathways engaged in cancer, including the receptor tyrosine kinases PDGFR and EGFR, PI3K/PTEN/AKT and Wnt-β-catenin pathways.

Ras-activated RSK1 phosphorylates EBP50 to regulate its nuclear localization and promote cell proliferation

Differential subcellular localization of EBP50 leads to its controversial role in cancer biology either as a tumor suppressor when it resides at the membrane periphery, or a tumor facilitator at the nucleus. However, the mechanism behind nuclear localization of EBP50 remains unclear. A RNA interference screening identified the downstream effector of the Ras-ERK cascade, RSK1, as the molecule unique for nuclear transport of EBP50. RSK1 binds to EBP50 and phosphorylates it at a conserved threonine residue at position 156 (T156) under the regulation of growth factor. Mutagenesis experiments confirmed the significance of T156 residue in nuclear localization of EBP50, cellular proliferation, and oncogenic transformation. Our study sheds light on a possible therapeutic strategy targeting at this aberrant nuclear expression of EBP50 without affecting the normal physiological function of EBP50 at other subcellular localization.

Mining for Candidate Genes Related to Pancreatic Cancer Using Protein-Protein Interactions and a Shortest Path Approach

Pancreatic cancer (PC) is a highly malignant tumor derived from pancreas tissue and is one of the leading causes of death from cancer. Its molecular mechanism has been partially revealed by validating its oncogenes and tumor suppressor genes; however, the available data remain insufficient for medical workers to design effective treatments. Large-scale identification of PC-related genes can promote studies on PC. In this study, we propose a computational method for mining new candidate PC-related genes. A large network was constructed using protein-protein interaction information, and a shortest path approach was applied to mine new candidate genes based on validated PC-related genes. In addition, a permutation test was adopted to further select key candidate genes. Finally, for all discovered candidate genes, the likelihood that the genes are novel PC-related genes is discussed based on their currently known functions.

Expression of Na+/H+ exchanger regulatory factor 1 in autosomal-dominant polycystic kidney disease

OBJECTIVE

To explore the role of Na(+)/H(+) exchanger regulatory factor 1 (NHERF1) in autosomal-dominant polycystic kidney disease (ADPKD).

METHODS

NHERF1 and β-catenin protein were detected by immunohistochemistry and Western blotting of kidney tissue samples from patients with ADPKD and controls (normal kidney tissue [>5 cm from the foci] collected from patients undergoing unilateral nephrectomy for kidney cancer). NHERF1 and β-catenin protein and mRNA were quantified by Western blot and real-time fluorescent quantitative polymerase chain reaction, respectively, in kidney tissue samples from Han:SPRD (+/+) and (cy/+) rats. The effects of human recombinant NHERF1 on proliferation and cell cycle of ADPKD cyst-lining epithelial cells (WT9-12) were evaluated by MTT assay and flow cytometry, respectively.

RESULTS

Levels of NHERF1 protein and mRNA were significantly lower, and β-catenin levels significantly higher, in patients with ADPKD and Han:SPRD (cy/+) rats, compared with control subjects and (+/+) rats, respectively. Exogenous recombinant NHERF1 significantly inhibited proliferation of WT9-12 cells and increased the proportion of cells in G(0)/G(1) phase.

CONCLUSIONS

ADPKD is associated with a decrease in NHERF1 protein and mRNA levels. Supplementing exogenous NHERF1 inhibited the proliferation of WT9-12 cells.

PRL-3 Promotes the Malignant Progression of Melanoma via Triggering Dephosphorylation and Cytoplasmic Localization of NHERF1

Phosphatase of regenerating liver-3 (PRL-3) has been reported to have a critical role in metastatic progression of cancers. Here, we investigate how PRL-3 increases the malignant degree of melanoma cells. The expression of PRL-3 increased gradually during the malignant progression of melanoma. The phosphorylation of Akt was elevated in highly malignant melanoma cells, which was accompanied by a decrease in nuclear phosphatase and tensin homolog (PTEN). The phosphorylation of NHERF1 in the serine site was regulated by PRL-3 and showed cytoplasmic translocation upon dephosphorylation, which resulted in a decrease in nuclear PTEN. The co-translocation of NHERF1 and PTEN from the nucleus to the cytoplasm was observed during the malignant progression of melanoma cells. Tumor growth was inhibited significantly, and the survival was prolonged upon knockdown of cytoplasmic NHERF1 in B16BL6 cells prior to the inoculation into mice. Taken together, to our knowledge previously unreported, we have identified NHERF1 as a potential substrate of PRL-3. Its phosphorylation status as well as its change in cellular localization and association with PTEN correlated with the malignant progression of melanoma. Our data provide an explanation for how PRL-3 promotes the malignant progression of melanoma, as well as a diagnostic marker or therapeutic target for malignant melanoma.

Possible biological and translational significance of mast cells density in colorectal cancer

Mast cells (MCs), located ubiquitously near blood vessels, are descended from CD34⁺ hematopoietic stem cells. Initially, although their role has been well defined in hypersensitivity reactions, the discovery of their sharing in both innate and adaptive immunity has allowed to redefine their crucial interplay on the regulatory function between inflammatory and tumor cells through the release of mediators granule-associated (mainly tryptase and vascular endothelial growth factor). In particular, in several animal and human malignancies it has been well demonstrated that activated c-Kit receptor (c-KitR) and tryptase (an agonist of the proteinase-activated receptor-2) take pivotal part in tumor angiogenesis after the MCs activation, contributing to tumor cells invasion and metastasis. In this review, we focused on crucial MCs density (MCD) role in colorectal cancer (CRC) development and progression angiogenesis-mediated; then, we will analyze the principal studies that have focused on MCD as possible prognostic factor. Finally, we will consider a possible role of MCD as novel therapeutic target mainly by c-KitR tyrosine kinase inhibitors (imatinib, masitinib) and tryptase inhibitors (gabexate and nafamostat mesylate) with the aim to prevent CRC progression.

High density of tryptase-positive mast cells in human colorectal cancer: a poor prognostic factor related to protease-activated receptor 2 expression

Tryptase(+) mast cells (MCs), abundant in the invasive front of tumours, contribute to tissue remodelling. Indeed, protease-activated receptor-2 (PAR-2) activation by MC-tryptase is considered an oncogenic event in colorectal cancer (CRC). Recently, we have suggested NHERF1 as a potential new marker in CRC. In this study, we aimed to determine the distribution of tryptase(+) MCs and PAR-2 and to examine the relationship between PAR-2 and NHERF1, investigating their reputed usefulness as tumour markers. We studied a cohort of 115 CRC specimens including primary cancer (C) and adjacent normal mucosa (NM) by immunohistochemical double staining, analyzing the protein expression of MC-tryptase, PAR-2 and cytoplasmic NHERF1. MC density was higher in NM than in C. Tumours with high TNM stage and poor grade showed the highest MC density. A higher PAR-2 immunoreactivity characterized tumours most infiltrated by MCs compared with samples with low MC density. Furthermore, PAR-2 overexpression was associated with advanced TNM stage, poor grade and lymphovascular invasion (LVI). A positive correlation existed between tryptase(+) MC density and PAR-2 expression. Cytoplasmic NHERF1 was higher in C than in NM and overexpressing tumours resulted associated with nodal and distant metastases, poor grade and LVI. PAR-2 correlated with cytoplasmic NHERF1 and the PAR-2(+)/cytoplasmic NHERF1(+) expression immunophenotype identified tumours associated with unfavourable prognosis and aggressive clinical parameters. Our data indicate that the high density of tryptase(+) MCs at invasive margins of tumours was associated with advanced stages of CRC and was strongly correlated with PAR-2 expression.

Nuclear NHERF1 expression as a prognostic marker in breast cancer

Our purpose was to investigate whether Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1) expression could be linked to prognosis in invasive breast carcinomas. NHERF1, an ezrin-radixin-moesin (ERM) binding phosphoprotein 50, is involved in the linkage of integral membrane proteins to the cytoskeleton. It is therefore believed to have an important role in cell signaling associated with changes in cell cytoarchitecture. NHERF1 expression is observed in various types of cancer and is related to tumor aggressiveness. To date the most extensive analyses of the influence of NHERF1 in cancer development have been performed on breast cancer. However, the underlying mechanism and its prognostic significance are still undefined. NHERF1 expression was studied by immunohistochemistry (IHC) in a cohort of 222 breast carcinoma patients. Association of cytoplasmic and nuclear NHERF1 expression with survival was analyzed. Disease-free survival (DFS) and overall survival (OS) were determined based on the Kaplan–Meier method. Cytoplasmic NHERF1 expression was associated with negative progesterone receptor (PgR) (P=0.017) and positive HER2 expression (P=0.023). NHERF1 also showed a nuclear localization and this correlated with small tumor size (P=0.026) and positive estrogen receptor (ER) expression (P=0.010). Multivariate analysis identified large tumor size (P=0.011) and nuclear NHERF1 expression (P=0.049) to be independent prognostic variables for DFS. Moreover, the nuclear NHERF1(−)/ER(−) immunophenotype (27%) was statistically associated with large tumor size (P=0.0276), high histological grade (P=0.0411), PgR-negative tumors (P<0.0001) and high proliferative activity (P=0.0027). These patients had worse DFS compared with patients with nuclear NHERF1(+)/ER(+) tumors (75.4% versus 92.6% P=0.010). These results show that the loss of nuclear NHERF1 expression is associated with reduced survival, and the link between nuclear NHERF1 and ER expression may serve as a prognostic marker for the routine clinical management of breast cancer patients.