Ezrin mediates c-Myc actions in prostate cancer cell invasion

Implications of c-Myc in the pathogenesis and treatment efficacy of urological cancers

Urological cancers, including prostate, bladder, and renal cancers, are significant causes of death and negatively impact the quality of life for patients. The development and progression of these cancers are linked to the dysregulation of molecular pathways. c-Myc, recognized as an oncogene, exhibits abnormal levels in various types of tumors, and current evidence supports the therapeutic targeting of c-Myc in cancer treatment. This review aims to elucidate the role of c-Myc in driving the progression of urological cancers. c-Myc functions to enhance tumorigenesis and has been documented to increase growth and metastasis in prostate, bladder, and renal cancers. Furthermore, the dysregulation of c-Myc can result in a diminished response to therapy in these cancers. Non-coding RNAs, β-catenin, and XIAP are among the regulators of c-Myc in urological cancers. Targeting and suppressing c-Myc therapeutically for the treatment of these cancers has been explored. Additionally, the expression level of c-Myc may serve as a prognostic factor in clinical settings.

MYC Oncogene: A Druggable Target for Treating Cancers with Natural Products

Various diseases, including cancers, age-associated disorders, and acute liver failure, have been linked to the oncogene, MYC. Animal testing and clinical trials have shown that sustained tumor volume reduction can be achieved when MYC is inactivated, and different combinations of therapeutic agents including MYC inhibitors are currently being developed. In this review, we first provide a summary of the multiple biological functions of the MYC oncoprotein in cancer treatment, highlighting that the equilibrium points of the MYC/MAX, MIZ1/MYC/MAX, and MAD (MNT)/MAX complexes have further potential in cancer treatment that could be used to restrain MYC oncogene expression and its functions in tumorigenesis. We also discuss the multifunctional capacity of MYC in various cellular cancer processes, including its influences on immune response, metabolism, cell cycle, apoptosis, autophagy, pyroptosis, metastasis, angiogenesis, multidrug resistance, and intestinal flora. Moreover, we summarize the MYC therapy patent landscape and emphasize the potential of MYC as a druggable target, using herbal medicine modulators. Finally, we describe pending challenges and future perspectives in biomedical research, involving the development of therapeutic approaches to modulate MYC or its targeted genes. Patients with cancers driven by MYC signaling may benefit from therapies targeting these pathways, which could delay cancerous growth and recover antitumor immune responses.

Androgen receptor and MYC transcriptomes are equilibrated in multilayer regulatory circuitries in prostate cancer

BACKGROUND

The discovery of androgen receptor (AR) having transrepression effects completes the circle of its functionalities as a typical transcription factor, which intrinsically bears dual functions of activation and repression linked to co-factor competition and redistribution. Indeed, AR dual functions are exemplified by locus-wide regulation of the oncogenic 8q24-MYC region.

METHODS

RT-qPCR assay and public RNA-profiling datasets were used to assess MYC transcription in androgen-sensitive cell lines. Public ChIP-seq and RNA-Seq datasets were computed to evaluate AR-MYC direct and indirect signatures. Gene sets in typical MYC and AR pathways were monitored to validate their cross-talks. Bio-informatics and chromosome conformation capture (3C) assay were performed in the AR gene locus to examine androgen-elicited distal regulation. Finally, co-factor re-distribution were globally tracked between AR and MYC binding sites.

RESULTS

In this report, we found MYC responded negatively to androgen with hypersensitivity, rivaling AR natural functions as an innate androgen effector. Furthermore, both direct and indirect AR and MYC transcriptional programs were actively in equilibration. With established androgen-mediated versus MYC-mediated gene subsets, we validated AR and MYC pathways were both bidirectional and extensively entangled. In addition, we determined that the AR gene locus resembled the MYC gene region and both loci were androgen-repressed via epigenetics and chromatin architectural alterations. Significantly, transcriptional factor profiling along the prostate cancer (PCa) genome exposed that PCa transcriptomes were dynamically equilibrated between AR-binding site and MYC-binding site.

CONCLUSION

Together, our findings stratified AR-MYC interactions that are extensively wired and intricately organized to compensate for essential PCa transcriptional programs and neutralize excessive signaling.

Dissecting transcription of the 8q24-MYC locus in prostate cancer recognizes the equilibration between androgen receptor direct and indirect dual-functions

BACKGROUND

Androgen receptor (AR) activation and repression dual-functionality only became known recently and still remains intriguing in prostate cancer (PCa). MYC is a prominent oncogene that functionally entangles with AR signaling in PCa. Further exploration of AR regulatory mechanisms on MYC gene transcription bears clinical and translation significance.

METHODS

Bioinformatics analysis of PCa cell line and clinical RNA-Seq and ChIP-Seq (chromatin immunoprecipitation-sequencing) datasets to anchor interactions of AR and MYC transcriptional networks. ChIP-qPCR and 3C (chromosome conformation capture) analyses to probe MYC distal regulation by AR binding sites (ABSs). CRISPR/Cas9-mediated genome-editing to specify functions of ABS within the 8q24-MYC locus on androgen-mediated MYC transcription. Global FoxA1 and HoxB13 distribution profiling to advance AR transcriptional mechanisms.

RESULTS

Here we recognize AR bi-directional transcription mechanisms by exploiting the prominent 8q24-MYC locus conferring androgen hyper-sensitivity. At ~ 25 Kb downstream of the MYC gene, we identified an undefined ABS, P10. By chromatin analyses, we validated androgen-dependent spatial interaction between P10 and MYC-Promoter (MYC-Pro) and temporal epigenetic repression of these MYC-proximal elements. We next designed a CRISPR/Cas9-mediated double genomic knock-out (KO) strategy to show that P10-KO slightly lessened androgen-elicited MYC transrepression in LNCaP-AR cells. In similar genomic editing assays, androgen-mediated MYC repression became slightly deepened upon KO of P11, an ABS in the PVT1 gene locus highly enriched in AR-binding motifs and peaks. We also investigated multiple ABSs in the established PCAT1 super-enhancer that distally interacts with MYC-Pro for transactivation, with each KO pool consistently shown to relieve androgen-elicited MYC repression. In the end, we systemically assessed androgen effects in the 8q24-MYC locus and along PCa genome to generalize H3K27ac and BRD4 re-distribution from pioneer factors (FoxA1 and HoxB13) to AR sites.

CONCLUSION

Together, we reconciled these observations by unifying AR dual-functions that are mechanistically coupled to and equilibrated by co-factor redistribution.

Ezrin Inhibition Overcomes Acquired Resistance to Vemurafenib in BRAFV600E-Mutated Colon Cancer and Melanoma Cells In Vitro

Despite the advancements in targeted therapy for BRAFV600E-mutated metastatic colorectal cancer (mCRC), the development of resistance to BRAFV600E inhibition limits the response rate and durability of the treatment. Better understanding of the resistance mechanisms to BRAF inhibitors will facilitate the design of novel pharmacological strategies for BRAF-mutated mCRC. The aim of this study was to identify novel protein candidates involved in acquired resistance to BRAFV600E inhibitor vemurafenib in BRAFV600E-mutated colon cancer cells using an integrated proteomics approach. Bioinformatic analysis of obtained proteomics data indicated actin-cytoskeleton linker protein ezrin as a highly ranked protein significantly associated with vemurafenib resistance whose overexpression in the resistant cells was additionally confirmed at the gene and protein level. Ezrin inhibition by NSC305787 increased anti-proliferative and pro-apoptotic effects of vemurafenib in the resistant cells in an additive manner, which was accompanied by downregulation of CD44 expression and inhibition of AKT/c-Myc activities. We also detected an increased ezrin expression in vemurafenib-resistant melanoma cells harbouring the BRAFV600E mutation. Importantly, ezrin inhibition potentiated anti-proliferative and pro-apoptotic effects of vemurafenib in the resistant melanoma cells in a synergistic manner. Altogether, our study suggests a role of ezrin in acquired resistance to vemurafenib in colon cancer and melanoma cells carrying the BRAFV600E mutation and supports further pre-clinical and clinical studies to explore the benefits of combined BRAF inhibitors and actin-targeting drugs as a potential therapeutic approach for BRAFV600E-mutated cancers.

Ezrin and Its Phosphorylated Thr567 Form Are Key Regulators of Human Extravillous Trophoblast Motility and Invasion

The protein ezrin has been shown to enhance cancer cell motility and invasion leading to malignant behaviours in solid tumours, but a similar regulatory function in the early physiological reproduction state is, however, much less clear. We speculated that ezrin may play a key role in promoting first-trimester extravillous trophoblast (EVT) migration/invasion. Ezrin, as well as its Thr567 phosphorylation, were found in all trophoblasts studied, whether primary cells or lines. Interestingly, the proteins were seen in a distinct cellular localisation in long, extended protrusions in specific regions of cells. Loss-of-function experiments were carried out in EVT HTR8/SVneo and Swan71, as well as primary cells, using either ezrin siRNAs or the phosphorylation Thr567 inhibitor NSC668394, resulting in significant reductions in both cell motility and cellular invasion, albeit with differences between the cells used. Our analysis further demonstrated that an increase in focal adhesion was, in part, able to explain some of the molecular mechanisms involved. Data collected using human placental sections and protein lysates further showed that ezrin expression was significantly higher during the early stage of placentation and, importantly, clearly seen in the EVT anchoring columns, further supporting the potential role of ezrin in regulating migration and invasion in vivo.

Role of ubiquitin specific proteases in the immune microenvironment of prostate cancer: A new direction

Regulation of ubiquitination is associated with multiple processes of tumorigenesis and development, including regulation of the tumor immune microenvironment. Deubiquitinating enzymes (DUBs) can remove ubiquitin chains from substrates, thereby stabilizing target proteins and altering and remodeling biological processes. During tumorigenesis, deubiquitination-altered biological processes are closely related to tumor metabolism, stemness, and the immune microenvironment. Recently, tumor microenvironment (TME) modulation strategies have attracted considerable attention in cancer immunotherapy. Targeting immunosuppressive mechanisms in the TME has revolutionized cancer therapy. Prostate cancer (PC) is one of the most common cancers and the second most common cause of cancer-related death in men worldwide. While immune checkpoint inhibition has produced meaningful therapeutic effects in many cancer types, clinical trials of anti-CTLA4 or anti-PD1 have not shown a clear advantage in PC patients. TME affects PC progression and also enables tumor cell immune evasion by activating the PD-1/PD-L1 axis. Over the past few decades, an increasing number of studies have demonstrated that deubiquitination in PC immune microenvironment may modulate the host immune system’s response to the tumor. As the largest and most diverse group of DUBs, ubiquitin-specific proteases (USPs) play an important role in regulating T cell development and function. According to current studies, USPs exhibit a high expression signature in PC and may promote tumorigenesis. Elevated expression of USPs often indicates poor tumor prognosis, suggesting that USPs are expected to develop as the markers of tumor prognosis and even potential drug targets for anti-tumor therapy. Herein, we first summarized recent advances of USPs in PC and focused on the relationship between USPs and immunity. Additionally, we clarified the resistance mechanisms of USPs to targeted drugs in PC. Finally, we reviewed the major achievement of targeting USPs in cancers.

Ezrin gone rogue in cancer progression and metastasis: An enticing therapeutic target

Cancer metastasis is the primary cause of morbidity and mortality in cancer as it remains the most complicated, devastating, and enigmatic aspect of cancer. Several decades of extensive research have identified several key players closely associated with metastasis. Among these players, cytoskeletal linker Ezrin (the founding member of the ERM (Ezrin-Radixin-Moesin) family) was identified as a critical promoter of metastasis in pediatric cancers in the early 21st century. Ezrin was discovered 40 years ago as a aminor component of intestinal epithelial microvillus core protein, which is enriched in actin-containing cell surface structures. It controls gastric acid secretion and plays diverse physiological roles including maintaining cell polarity, regulating cell adhesion, cell motility and morphogenesis. Extensive research for more than two decades evinces that Ezrin is frequently dysregulated in several human cancers. Overexpression, altered subcellular localization and/or aberrant activation of Ezrin are closely associated with higher metastatic incidence and patient mortality, thereby justifying Ezrin as a valuable prognostic biomarker in cancer. Ezrin plays multifaceted role in multiple aspects of cancer, with its significant contribution in the complex metastatic cascade, through reorganizing the cytoskeleton and deregulating various cellular signaling pathways. Current preclinical studies using genetic and/or pharmacological approaches reveal that inactivation of Ezrin results in significant inhibition of Ezrin-mediated tumor growth and metastasis as well as increase in the sensitivity of cancer cells to various chemotherapeutic drugs. In this review, we discuss the recent advances illuminating the molecular mechanisms responsible for Ezrin dysregulation in cancer and its pleiotropic role in cancer progression and metastasis. We also highlight its potential as a prognostic biomarker and therapeutic target in various cancers. More importantly, we put forward some potential questions, which we strongly believe, will stimulate both basic and translational research to better understand Ezrin-mediated malignancy, ultimately leading to the development of Ezrin-targeted cancer therapy for the betterment of human life.

[EEFSEC knockdown inhibits proliferation, migration and invasion of prostate cancer cells in vitro]

OBJECTIVE

To investigate the role of selenocysteine-tRNA specific eukaryotic elongation factor (EEFSEC) in regulating the proliferation, migration, and invasion of human prostate cancer 22Rv1 cells.

METHODS

We detected EEFSEC mRNA expression levels in human normal prostate cell line RWPE1 and human prostate cancer cell lines 22Rv1, LNCaP, Vcap and PC-3 using qRT-PCR and EEFSEC protein expression in surgical specimens of prostate cancer and adjacent tissues using Western blotting. 22Rv1 cells were infected with a lentiviral vector carrying EEFSEC shRNA or a control lentivirus and the interference efficiency was determined using Western blotting. XTT assay was used to assess the changes in the viability of the infected cells, and Transwell chamber assay was used to examine the changes in cell migration and invasion. The effect of EEFSEC knockdown on cell cycle progression was determined with flow cytometry and by detecting the expressions of cell cycle proteins using qRT-PCR.

RESULTS

EEFSEC was significantly upregulated in prostate cancer cells (P < 0.05), and a high expression of EEFSEC was associated with a poor prognosis of the patients with prostate cancer. In 22Rv1 cells, EEFSEC knockdown significantly suppressed the proliferation (P < 0.001), migration (P < 0.001) and invasion (P < 0.001) of the cells, resulted in cell cycle arrest in G₀/G₁ phase, obviously inhibited the expression of C-myc and CCNB1, and significantly increased the expression of p15.

CONCLUSION

EEFSEC knockdown can inhibit the proliferation, migration, and invasion of prostate cancer cells in vitro possibly by down-regulating the expression of C-myc.

Novel CTRP8-RXFP1-JAK3-STAT3 axis promotes Cdc42-dependent actin remodeling for enhanced filopodia formation and motility in human glioblastoma cells

C1q tumor necrosis factor‐related peptide 8 (CTRP8) is the least studied member of the C1Q‐TNF‐related peptide family. We identified CTRP8 as a ligand of the G protein‐coupled receptor relaxin family peptide receptor 1 (RXFP1) in glioblastoma multiforme (GBM). The CTRP8‐RXFP1 ligand–receptor system protects human GBM cells against the DNA‐alkylating damage‐inducing temozolomide (TMZ), the drug of choice for the treatment of patients with GBM. The DNA protective role of CTRP8 was dependent on a functional RXFP1‐STAT3 signaling cascade and targeted the monofunctional glycosylase N‐methylpurine DNA glycosylase (MPG) for more efficient base excision repair of TMZ‐induced DNA‐damaged sites. CTRP8 also improved the survival of GBM cells by upregulating anti‐apoptotic BCl‐2 and BCL‐XL. Here, we have identified Janus‐activated kinase 3 (JAK3) as a novel member of a novel CTRP8‐RXFP1‐JAK3‐STAT3 signaling cascade that caused an increase in cellular protein content and activity of the small Rho GTPase Cdc42. This is associated with significant F‐actin remodeling and increased GBM motility. Cdc42 was critically important for the upregulation of the actin nucleation complex N‐Wiskott–Aldrich syndrome protein/Arp3/4 and actin elongation factor profilin‐1. The activation of the RXFP1‐JAK3‐STAT3‐Cdc42 axis by both RXFP1 agonists, CTRP8 and relaxin‐2, caused extensive filopodia formation. This coincided with enhanced activity of ezrin, a key factor in tethering F‐actin to the plasma membrane, and inhibition of the actin filament severing activity of cofilin. The F‐actin remodeling and pro‐migratory activities promoted by the novel RXFP1‐JAK3‐STAT3‐Cdc42 axis were blocked by JAK3 inhibitor tofacitinib and STAT3 inhibitor STAT3 inhibitor VI. This provides a new rationale for the design of JAK3 and STAT3 inhibitors with better brain permeability for clinical treatment of the pervasive brain invasiveness of GBM.

Nuclear factor IX promotes glioblastoma development through transcriptional activation of Ezrin

Enhanced migration is pivotal for the malignant development of glioblastoma (GBM), but the underlying molecular mechanism that modulates the migration of the GBM cells remains obscure. Here we show that nuclear factor IX (NFIX) is significantly upregulated in human GBM lesions compared with normal or low-grade gliomas. NFIX deficiency impairs the migration of GBM cells and inhibits the tumor growth in the hippocampus of immunodeficient nude mice. Mechanistically, NFIX silencing suppresses the expression of Ezrin, a protein that crosslinks actin cytoskeleton and plasma membrane, which is also positively correlated with GBM malignancy. NFIX depletion induced migration inhibition of GBM cells can be rescued by the replenishment of Ezrin. Furthermore, we identify a NFIX response element (RE) between −840 and −825 bp in the promoter region of the Ezrin gene. Altogether, our findings show, for the first time that NFIX can transcriptionally upregulate the expression of Ezrin and contribute to the enhanced migration of GBM cells, suggesting that NFIX is a potential target for GBM therapy.

microRNA-211 regulates cell proliferation, apoptosis and migration/invasion in human osteosarcoma via targeting EZRIN

Background

In recent years, microRNA-211 (miR211) has been considered as a tumor suppressor in multiple malignancies. However, the function of miR211 in human osteosarcoma has not been explored intensively so far. In this study, the relationship between miR211 and EZRIN was analyzed in human osteosarcoma.

Methods

The expression levels of miR211 and EZRIN were measured in both human osteosarcoma cells and tissues. The direct regulatory relationship between miR211 and EZRIN was evaluated using dual-luciferase assay. The effect of miR211 and EZRIN overexpression on cell proliferation, migration/invasion, and apoptosis was detected.

Results

The expression of miR211 was obviously lower in osteosarcoma tissues than paracancerous tissues. EZRIN was identified as the direct target of miR211, and up-regulation of miR211 increased the percentage of cell apoptosis, and suppressed cell proliferation as well as cell migration/invasion via directly regulating EZRIN.

Conclusions

Our study indicated that miR211 has an important role in the development and progress of osteosarcoma, and it might become a novel target in the diagnosis and treatment of human osteosarcoma.

Electronic supplementary material

The online version of this article (10.1186/s11658-019-0173-x) contains supplementary material, which is available to authorized users.

Ezrin promotes breast cancer progression by modulating AKT signals

Background

Ezrin, which is known as a cytoskeleton linker protein, is closely linked with the metastatic progression of cancer and is frequently abnormally expressed in aggressive cancer types. However, the possible involvement of Ezrin in metastasis and angiogenesis in breast cancer remains unclear.

Methods

Immunohistochemical analysis of Ezrin was performed on both BC samples (n = 117) and normal epithelium samples (n = 47). In vivo and in vitro assays were performed to validate the effect of Ezrin on AKT pathway-mediated BC progression.

Results

In this study, Ezrin was found to be upregulated in BC tissues, which was linked with aggressive tumour characteristics and poor prognosis. Moreover, we showed that Ezrin promotes BC proliferation, migration, invasion, and angiogenesis in vitro and in vivo. Mechanistic analysis showed that Ezrin interacted with AKT, and promoted its kinase activity, thereby regulating the AKT pathway in BC.

Conclusions

In all, we propose a model for an Ezrin/AKT oncoprotein axis, which provides novel insight into how Ezrin contributes to BC progression.

A Novel Three-Gene Model Predicts Prognosis and Therapeutic Sensitivity in Esophageal Squamous Cell Carcinoma

To precisely predict the clinical outcome and determine the optimal treatment options for patients with esophageal squamous cell carcinoma (ESCC) remains challenging. Prognostic models based on multiple molecular markers of tumors have been shown to have superiority over the use of single biomarkers. Our previous studies have identified the crucial role of ezrin in ESCC progression, which prompted us to hypothesize that ezrin-associated proteins contribute to the pathobiology of ESCC. Herein, we explored the clinical value of a molecular model constructed based on ezrin-associated proteins in ESCC patients. We revealed that the ezrin-associated proteins (MYC, PDIA3, and ITGA5B1) correlated with the overall survival (OS) and disease-free survival (DFS) of patients with ESCC. High expression of MYC was associated with advanced pTNM-stage (P=0.011), and PDIA3 and ITGA5B1 were correlated with both lymph node metastasis (PDIA3: P < 0.001; ITGA5B1: P=0.001) and pTNM-stage (PDIA3: P=0.001; ITGA5B1: P=0.009). Furthermore, we found that, compared with the current TNM staging system, the molecular model elicited from the expression of MYC, PDIA3, and ITGA5B1 shows higher accuracy in predicting OS (P < 0.001) or DFS (P < 0.001) in ESCC patients. Moreover, ROC and regression analysis demonstrated that this model was an independent predictor for OS and DFS, which could also help determine a subgroup of ESCC patients that may benefit from chemoradiotherapy. In conclusion, our study has identified a novel molecular prognosis model, which may serve as a complement for current clinical risk stratification approaches and provide potential therapeutic targets for ESCC treatment.

Ezrin/NF-κB Pathway Regulates EGF-induced Epithelial-Mesenchymal Transition (EMT), Metastasis, and Progression of Osteosarcoma

Background

Epithelial-mesenchymal transition (EMT) is responsible for metastasis of cancers, and NF-κB can promote tumor progression. Ezrin is an important molecule participating in EMT. However, whether Ezrin mediates NF-κB in EGF-induced osteosarcoma is unknown.

Material/Methods

Ezrin phosphorylation, NF-κB activation, and EGF-induced EMT were studied in MG63 and U20S cells with NF-κB inhibition, silencing, or over-expressing Ezrin. Cell morphology, proliferation, migration, and motility were analyzed. An osteosarcoma model was established in mice by injecting MG63 and U20S and reducing Ezrin.

Results

With EGF induction in vitro, Ezrin Tyr353 and Thr567 were phosphorylated, and EMT, proliferation, migration, and motility of osteosarcoma cells were promoted. Silencing Ezrin suppressed and over-expressing Ezrin promoted the nuclear translocation of p65 and phosphorylated IκBα (p-IκBα) in EGF-induced osteosarcoma cells. NF-κB inhibitor blocked EGF-induced EMT in both cell types, as well as reserving cell morphology and suppressing proliferation, migration, and motility. In vivo, reducing Ezrin significantly suppressed metastasis of osteosarcoma xenografts, increased liver and lung weights, and activated NF-κB, which were both induced by EGF.

Conclusions

Ezrin/NF-κB regulated EGF-induced EMT, as well as progression and metastasis of osteosarcoma in vivo and in vitro. Ezrin/NF-κB may be a new therapeutic target to prevent osteosarcoma from deterioration.

Sterol regulatory element-binding protein 1 cooperates with c-Myc to promote epithelial-mesenchymal transition in colorectal cancer

Metastasis is the primary cause of mortality in colorectal cancer (CRC), the mechanism of which remains unclear. In the present study, by detecting mRNA expression using a reverse transcription-quantitative polymerase chain reaction (qPCR), it was revealed that sterol regulatory element-binding protein 1 (SREBP1) is highly expressed in CRC. Using a cell wound healing assay and a cell invasion assay, a novel metastasis-promoting role for SREBP1 in CRC was identified. Furthermore, snail family transcriptional repressor 1 (SNAIL) was identified as a key downstream effector of SREBP1 in CRC by the use of small interfering RNA against SNAIL. Additionally, using co-immunoprecipitation and chromatin immunoprecipitation-qPCR assays, it was demonstrated that SREBP1 interacts with c-MYC to enhance the binding of c-MYC to the promoter of the mesenchymal gene, SNAIL, thereby increasing SNAIL expression and accelerating epithelial-mesenchymal transition. These results indicated a novel role for SREBP1 and provide insight into the regulatory mechanisms of the c-Myc oncogene in CRC, which may function as a potential therapeutic target for CRC treatment.

Ezrin mediates both HGF/Met autocrine and non-autocrine signaling-induced metastasis in melanoma

Aberrant HGF/Met signaling promotes tumor migration, invasion, and metastasis through both autocrine and non-autocrine mechanisms; however, the molecular downstream signaling mechanisms by which HGF/Met induces metastasis are incompletely understood. We here report that Ezrin expression is stimulated by HGF and correlates with activated HGF/Met, indicating that HGF/Met signaling regulates the expression of Ezrin. We show that HGF/Met signaling activates the transcription factor Sp1 through the MAPK pathway, and activated Sp1 can in turn directly bind to the promoter of Ezrin gene and regulate its transcription. Notably, knockdown of Ezrin expression by shRNAs inhibits the metastasis induced by either HGF/Met autocrine or non-autocrine signaling in syngeneic wildtype and HGF transgenic mouse hosts. We also used small molecule drugs in preclinical mouse models to confirm that Ezrin is one of the downstream molecules mediating HGF/Met signaling-induced metastasis in melanoma. We conclude that Ezrin is a key downstream factor involved in the regulation of HGF/Met signaling-induced metastasis and demonstrate a link between Ezrin and HGF/Met/MAPK/Sp1 activation in the metastatic process. Our data indicate that Ezrin represents a promising therapeutic target for patients bearing tumors with activated HGF/Met signaling.

Ezrin contributes to cervical cancer progression through induction of epithelial-mesenchymal transition

Cervical cancer is the third most common cancer in females worldwide. The treatment options for advanced cervical cancer are limited, leading to high mortality. Ezrin is a membrane-cytoskeleton-binding protein recently reported to act as a tumor promoter, and we previously indicated that the aberrant localization and overexpression of Ezrin could be an independent effective biomarker for prognostic evaluation of cervical cancers. In this study, we identified Ezrin as a regulator of epithelial-mesenchymal transition (EMT) and metastasis in cervical cancer. Ezrin knock-down inhibited anchorage-independent growth, cell migration, and invasion of cervical cancer cell lines in vitro and in vivo. EMT was inhibited in Ezrin-depleted cells, with up-regulation of E-cadherin and Cytokeratin-18 (CK-18) and down-regulation of mesenchymal markers. Ezrin knock-down also induced Akt phosphorylation. These results implicate Ezrin as an EMT regulator and tumor promoter in cervical cancer, and down-regulation of Ezrin suppressed cervical cancer progression, possibly via the phosphoinositide 3-kinase/Akt pathway. Furthermore, the expression pattern of Ezrin protein was closely related with the lymphovascular invasion status of cervical cancer by immunohistochemistry, and the survival analysis revealed that the cervical cancer patients with the perinuclear Ezrin expression pattern had longer survival time than those with the cytoplasmic Ezrin expression pattern. Ezrin thus represents a promising target for the development of novel and effective strategies aimed at preventing the progression of cervical cancer.

A decision tree-based combination of ezrin-interacting proteins to estimate the prognostic risk of patients with esophageal squamous cell carcinoma

Our previous studies have highlighted the importance of ezrin in esophageal squamous cell carcinoma (ESCC). Here our objective was to explore the clinical significance of ezrin-interacting proteins, which would provide a theoretical basis for understanding the function of ezrin and potential therapeutic targets for ESCC. We used affinity purification and mass spectrometry to identify PDIA3, CNPY2, and STMN1 as potential ezrin-interacting proteins. Confocal microscopy and coimmunoprecipitation analysis further confirmed the colocalization and interaction of ezrin with PDIA3, CNPY2, and STMN1. Tissue microarray data of ESCC samples (n=263) showed that the 5-year overall survival (OS) and disease-free survival (DFS) were significantly lower for the CNPY2 (OS, P=.003; DFS, P=.011) and STMN1 (OS, P=.010; DFS, P=.002) high-expression groups compared with the low-expression groups. By contrast, overexpression of PDIA3 was significantly correlated with favorable survival (OS, P<.001; DFS, P=.001). Cox regression demonstrated the prognostic value of PDIA3, CNPY2, and STMN1 in ESCC. Furthermore, decision tree analysis revealed that the resulting classifier of both ezrin and its interacting proteins could be used to better predict OS and DFS of patients with ESCC. In conclusion, a signature of ezrin-interacting proteins accurately predicts ESCC patient survival or tumor recurrence.

Ezrin/NF-kB activation regulates epithelial- mesenchymal transition induced by EGF and promotes metastasis of colorectal cancer

There is growing evidence that epithelial mesenchymal-transition (EMT) plays significant roles in terms of tumor metastasis. There are a lot of cytokines inducing EMT of tumor cells, EGF is one of the important cytokines.Ezrin is a connexin between the cytoskeleton and the cell membrane, which is closely related to the morphological movement and metastasis of tumor cells.EGF can activate Ezrin and affects cell motility. In recent years, many studies have shown that NF-kB acts as an important transcription factor, involving in the process of EMT. However, does Ezrin participate in the regulation of EGF-induced EMT through the NF-kB pathway? This question needs us to discuss.In the present study, we found that EGF could induce colorectal cancer cells to develop EMT,enhance their ability to invade and migrate and promotes phosphorylation of Ezrin Tyr353.On the other hand, inhibition of Ezrin could reverse EGF-induced EMT and inhibit NF-kB P65 translocating into the nucleus. Finally, knockout of Ezrin inhibited EGF-induced lung metastasis of colorectal cancer xenografts and abnormal activation of Ezrin and NF-kB were related with colorectal cancer metastasis and poor prognosis. Our present results suggest that Ezrin/NF-kB pathway may provide experimental evidence for new targeted drugs for colorectal cancer metastasis.

Correlation of Ezrin Expression Pattern and Clinical Outcomes in Ewing Sarcoma

Background. Ezrin is a membrane-cytoskeleton linker protein that has been associated with metastasis and poor outcomes in osteosarcoma and high-grade soft tissue sarcomas. The prognostic value of ezrin expression in Ewing sarcoma is unknown. Methods. The relationship between ezrin expression and outcome was analyzed in a cohort of 53 newly diagnosed Ewing sarcoma patients treated between 2000 and 2011. The intensity and proportion of cells with ezrin immunoreactivity were assessed in diagnostic tumor tissue using a semiquantitative scoring system to yield intensity and positivity scores for each tumor. Results. Ezrin expression was detected in 72% (38/53) of tumor samples. The proportion of patients with metastatic disease was equal in the positive and negative ezrin expression groups. There was no significant difference in the 5-year event-free survival (EFS) between patients with positive versus negative ezrin expression. Patients whose tumor sample showed high ezrin intensity had significantly better 5-year EFS when compared to patients with low/no ezrin intensity (78% versus 55%; P = 0.03). Conclusions. Ezrin expression can be detected in the majority of Ewing sarcoma tumor samples. Intense ezrin expression may be correlated with a favorable outcome; however further investigation with a larger cohort is needed to validate this finding.

A glimpse of the ERM proteins

In all eukaryotes, the plasma membrane is critically important as it maintains the architectural integrity of the cell. Proper anchorage and interaction between the plasma membrane and the cytoskeleton is critical for normal cellular processes. The ERM (ezrin-radixin-moesin) proteins are a class of highly homologous proteins involved in linking the plasma membrane to the cortical actin cytoskeleton. This review takes a succinct look at the biology of the ERM proteins including their structure and function. Current reports on their regulation that leads to activation and deactivation was examined before taking a look at the different interacting partners. Finally, emerging roles of each of the ERM family members in cancer was highlighted.

Prognostic Value of Ezrin in Various Cancers: A Systematic Review and Updated Meta-analysis

More and more studies have investigated the effects of Ezrin expression level on the prognostic role in various tumors. However, the results remain controversial rather than conclusive. Here, we performed a systematic review and meta-analysis to evaluate the correlation of Ezrin expression with the prognosis in various tumors. the pooled hazard ratios (HR) with the corresponding 95% confidence intervals (95% CI) were calculated to evaluate the degree of the association. The overall results of fifty-five studies with 6675 patients showed that elevated Ezrin expression was associated with a worse prognosis in patients with cancers, with the pooled HRs of 1.86 (95% CI: 1.51–2.31, P < 0.001) for over survival (OS), 2.55 (95% CI: 2.14–3.05, P < 0.001) for disease-specific survival (DFS) and 2.02 (95% CI: 1.13–3.63, P = 0.018) for disease-specific survival (DSS)/metastasis-free survival (MFS) by the random, fixed and random effect model respectively. Similar results were also observed in the stratified analyses by tumor types, ethnicity background and sample source. This meta-analysis suggests that Ezrin may be a potential prognostic marker in cancer patients. High Ezrin is associated with a poor prognosis in a variety of solid tumors.

The Proteome of Primary Prostate Cancer

BACKGROUND

Clinical management of the prostate needs improved prognostic tests and treatment strategies. Because proteins are the ultimate effectors of most cellular reactions, are targets for drug actions and constitute potential biomarkers; a quantitative systemic overview of the proteome changes occurring during prostate cancer (PCa) initiation and progression can result in clinically relevant discoveries.

OBJECTIVES

To study cellular processes altered in PCa using system-wide quantitative analysis of changes in protein expression in clinical samples and to identify prognostic biomarkers for disease aggressiveness.

DESIGN, SETTING, AND PARTICIPANTS

Mass spectrometry was used for genome-scale quantitative proteomic profiling of 28 prostate tumors (Gleason score 6-9) and neighboring nonmalignant tissue in eight cases, obtained from formalin-fixed paraffin-embedded prostatectomy samples. Two independent cohorts of PCa patients (summing 752 cases) managed by expectancy were used for immunohistochemical evaluation of proneuropeptide-Y (pro-NPY) as a prognostic biomarker.

RESULTS AND LIMITATIONS

Over 9000 proteins were identified as expressed in the human prostate. Tumor tissue exhibited elevated expression of proteins involved in multiple anabolic processes including fatty acid and protein synthesis, ribosomal biogenesis and protein secretion but no overt evidence of increased proliferation was observed. Tumors also showed increased levels of mitochondrial proteins, which was associated with elevated oxidative phosphorylation capacity measured in situ. Molecular analysis indicated that some of the proteins overexpressed in tumors, such as carnitine palmitoyltransferase 2 (CPT2, fatty acid transporter), coatomer protein complex, subunit alpha (COPA, vesicle secretion), and mitogen- and stress-activated protein kinase 1 and 2 (MSK1/2, protein kinase) regulate the proliferation of PCa cells. Additionally, pro-NPY was found overexpressed in PCa (5-fold, p<0.05), but largely absent in other solid tumor types. Pro-NPY expression, alone or in combination with the ERG status of the tumor, was associated with an increased risk of PCa specific mortality, especially in patients with Gleason score ≤ 7 tumors.

CONCLUSIONS

This study represents the first system-wide quantitative analysis of proteome changes associated to localized prostate cancer and as such constitutes a valuable resource for understanding the complex metabolic changes occurring in this disease. We also demonstrated that pro-NPY, a protein that showed differential expression between high and low risk tumors in our proteomic analysis, is also a PCa specific prognostic biomarker associated with increased risk for disease specific death in patients carrying low risk tumors.

PATIENT SUMMARY

The identification of proteins whose expression change in prostate cancer provides novel mechanistic information related to the disease etiology. We hope that future studies will prove the value of this proteome dataset for development of novel therapies and biomarkers.

Ezrin regulates focal adhesion and invadopodia dynamics by altering calpain activity to promote breast cancer cell invasion

Ezrin regulates proper focal adhesion and invadopodia turnover by regulating calpain-1, in part by directing its proteolytic activity toward key substrates talin, FAK, and cortactin. Ezrin-deficient tumor cells show reduced lung seeding and colonization in vivo but not primary tumor growth, thus implicating ezrin as a metastasis-associated protein.

Up-regulation of the cytoskeleton linker protein ezrin frequently occurs in aggressive cancer types and is closely linked with metastatic progression. However, the underlying molecular mechanisms detailing how ezrin is involved in the invasive and metastatic phenotype remain unclear. Here we report a novel function of ezrin in regulating focal adhesion (FA) and invadopodia dynamics, two key processes required for efficient invasion to occur. We show that depletion of ezrin expression in invasive breast cancer cells impairs both FA and invadopodia turnover. We also demonstrate that ezrin-depleted cells display reduced calpain-mediated cleavage of the FA and invadopodia-associated proteins talin, focal adhesion kinase (FAK), and cortactin and reduced calpain-1–specific membrane localization, suggesting a requirement for ezrin in maintaining proper localization and activity of calpain-1. Furthermore, we show that ezrin is required for cell directionality, early lung seeding, and distant organ colonization but not primary tumor growth. Collectively our results unveil a novel mechanism by which ezrin regulates breast cancer cell invasion and metastasis.

O-linked mannose β-1,2-N-acetylglucosaminyltransferase 1 correlated with the malignancy in glioma

O-linked mannose β-1,2-N-acetylglucosaminyltransferase 1 (PomGnT1) constitutes one third of the O-linked glycoproteins in brain tissue. However, its functions have been seldom investigated in brain cancers. In this study, immunohistochemistry was used for the detection of the PomGnT1 protein in 133 cases of glioma tissues. Spearman correlation analysis was used for the relationship between PomGnT1 staining and the glioma grade. Receiver operating characteristic curve was used to measure the diagnostic value of PomGnT1 protein in the degree of glioma malignance. We found that PomGnT1 expression was correlated with glioma grade, and it could be used as a marker to distinguish low- and high-grade gliomas. Stably transfected U87 cells were constructed to overexpress short hairpin RNA of PomGnT1. Immunofluorescence test detected that this protein also could restrain the generation of U87 cells' pseudopodia. Western blotting further showed that the PomGnT1 protein had an impact on the c-myc protein level. In conclusion, our data suggest that PomGnT1 protein was correlated with the malignance of glioma progression, the mechanism involved in glioma cell's pseudopodium formation, and the expression of c-myc protein.

Expression of ezrin, CD44, and VEGF in giant cell tumor of bone and its significance

Background

This research aimed to study the role of ezrin, CD44, and VEGF in invasion, metastasis, recurrence, and prognosis of giant cell tumor of bone (GCTB) and its association with the clinical and pathological features of GCTB.

Methods

Expression status of ezrin, CD44, and VEGF in 80 GCTB tissues and its adjacent noncancerous tissue samples were measured with immunohistochemical and Elivison staining. Their correlation with the clinical and pathologic factors was statistically analyzed by chi-square test.

Results

The expression status of ezrin, CD44, and VEGF were significantly higher in GCTB tissue samples than in its adjacent noncancerous tissue samples and in GCTB at Campanacci stage III than in Campanacci stages I and II (P < 0.05). No significant difference was found in age and sex of the patients and locations of the tumor (P > 0.05). Survival analysis showed that the expression status of ezrin, CD44, VEGF, and Campanacci clinical stages of GCTB were positively associated with the survival rate of GCTB patients and negatively associated with ezrin and Campanacci stages of GCTB, indicating that ezrin, CD44, VEGF, and Campanacci clinical stages of GCTB are the independent factors for GCTB.

Conclusions

Ezrin, CD44, and VEGF are over-expressed in GCTB tissue and its adjacent noncancerous tissue samples and may play an important role in the occurrence, invasion, metastasis, and recurrence of GCTB. Measurement of ezrin, CD44, and VEGF expression status may contribute to the judgment of prognosis of GCTB patients.

Expression and significance of CD44, CD47 and c-met in ovarian clear cell carcinoma

AIMS

The aim of the present study is to investigate the differential expression of CD44, CD47 and c-met in ovarian clear cell carcinoma (OCCC), the correlation in their expression and their relationship with the biological behavior of OCCC.

METHODS

We used immunohistochemistry to examine the expression of CD44, CD47 and c-met in OCCC (86 cases) and investigated the effects of the expression and interaction of these molecules on the development of OCCC.

RESULTS

CD44, CD47 and c-met expression was significantly high in OCCC. Expression of CD44 and CD47 correlated with patient surgical stage, chemotherapy resistance and prognosis (all p<0.05), and expression of c-met correlated with chemotherapy resistance and prognosis (all p<0.05), but did not correlate with lymph node metastasis (all p>0.05). The surgical stage, CD44, CD47 and c-met expression were independent risk factors for OCCC prognosis (all p<0.05). Patients with low levels of CD44, CD47 and c-met showed better survival than those with high levels (all p<0.05). There was a positive correlation between CD44 (or CD47) and c-met, as well as between CD44 and CD47 (the Spearman correlation coefficient rs was 0.783, 0.776 and 0.835, respectively, all p<0.01). Additionally, pairwise correlation analysis of these three markers shows that the high expression of CD44/CD47, CD44/c-met and CD47/c-met were correlated with patient surgical stage, chemotherapy resistance and prognosis (all p<0.05), but did not correlate with lymph node metastasis (all p>0.05).

CONCLUSIONS

Expression of CD44, CD47 and c-met was upregulated in OCCC and pairwise correlation. CD44, CD47 and c-met may have synergistic effects on the development of OCCC and are prognostic factors for ovarian cancer.

OTUB1 de-ubiquitinating enzyme promotes prostate cancer cell invasion in vitro and tumorigenesis in vivo

Background

Ubiquitination is a highly dynamic and reversible process with a central role in cell homeostasis. Deregulation of several deubiquitinating enzymes has been linked to tumor development but their specific role in prostate cancer progression remains unexplored.

Methods

RNAi screening was used to investigate the role of the ovarian tumor proteases (OTU) family of deubiquitinating enzymes on the proliferation and invasion capacity of prostate cancer cells. RhoA activity was measured in relation with OTUB1 effects on prostate cancer cell invasion. Tumor xenograft mouse model with stable OTUB1 knockdown was used to investigate OTUB1 influence in tumor growth.

Results

Our RNAi screening identified OTUB1 as an important regulator of prostate cancer cell invasion through the modulation of RhoA activation. The effect of OTUB1 on RhoA activation is important for androgen-induced repression of p53 expression in prostate cancer cells. In localized prostate cancer tumors OTUB1 was found overexpressed as compared to normal prostatic epithelial cells. Prostate cancer xenografts expressing reduced levels of OTUB1 exhibit reduced tumor growth and reduced metastatic dissemination in vivo.

Conclusions

OTUB1 mediates prostate cancer cell invasion through RhoA activation and promotes tumorigenesis in vivo. Our results suggest that drugs targeting the catalytic activity of OTUB1 could potentially be used as therapeutics for metastatic prostate cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-014-0280-2) contains supplementary material, which is available to authorized users.

ERM proteins in cancer progression

Members of the ezrin-radixin-moesin (ERM) family of proteins are involved in multiple aspects of cell migration by acting both as crosslinkers between the membrane, receptors and the actin cytoskeleton, and as regulators of signalling molecules that are implicated in cell adhesion, cell polarity and migration. Increasing evidence suggests that the regulation of cell signalling and the cytoskeleton by ERM proteins is crucial during cancer progression. Thus, both their expression levels and subcellular localisation would affect tumour progression. High expression of ERM proteins has been shown in a variety of cancers. Mislocalisation of ERM proteins reduces the ability of cells to form cell-cell contacts and, therefore, promotes an invasive phenotype. Similarly, mislocalisation of ERM proteins impairs the formation of receptor complexes and alters the transmission of signals in response to growth factors, thereby facilitating tumour progression. In this Commentary, we address the structure, function and regulation of ERM proteins under normal physiological conditions as well as in cancer progression, with particular emphasis on cancers of epithelial origin, such as those from breast, lung and prostate. We also discuss any recent developments that have added to the understanding of the underlying molecular mechanisms and signalling pathways these proteins are involved in during cancer progression.

In vivo quantitative phosphoproteomic profiling identifies novel regulators of castration-resistant prostate cancer growth

Prostate cancer remains a leading cause of cancer-related mortality worldwide owing to our inability to treat effectively castration-resistant tumors. To understand the signaling mechanisms sustaining castration-resistant growth, we implemented a mass spectrometry-based quantitative proteomic approach and use it to compare protein phosphorylation in orthotopic xenograft tumors grown in either intact or castrated mice. This investigation identified changes in phosphorylation of signaling proteins such as MEK, LYN, PRAS40, YAP1 and PAK2, indicating the concomitant activation of several oncogenic pathways in castration-resistant tumors, a notion that was confirmed by tumor transcriptome analysis. Further analysis demonstrated that the activation of mTORC1, PAK2 and the increased levels of YAP1 in castration-resistant tumors can be explained by the loss of androgen inhibitory actions. The analysis of clinical samples demonstrated elevated levels of PAK2 and YAP1 in castration-resistant tumors, whereas knockdown experiments in androgen-independent cells demonstrated that both YAP1 and PAK2 regulate cell colony formation and cell invasion activity. PAK2 also influenced cell proliferation and mitotic timing. Interestingly, these phenotypic changes occur in the absence of obvious alterations in the activity of AKT, MAPK or mTORC1 pathways, suggesting that PAK2 and YAP1 may represent novel targets for the treatment of castration-resistant prostate cancer. Pharmacologic inhibitors of PAK2 (PF-3758309) and YAP1 (Verteporfin) were able to inhibit the growth of androgen-independent PC3 xenografts. This work demonstrates the power of applying high-resolution mass spectrometry in the proteomic profiling of tumors grown in vivo for the identification of novel and clinically relevant regulatory proteins.

Akt/Ezrin Tyr353/NF-κB pathway regulates EGF-induced EMT and metastasis in tongue squamous cell carcinoma

BACKGROUND

Epithelial-mesenchymal transition (EMT) is a crucial programme in cancer metastasis. Epidermal growth factor (EGF) is a key inducer of EMT, and Ezrin has an important role in this process. However, how Ezrin is activated and whether it mediates EGF-induced EMT in tongue squamous cell carcinomas (TSCCs) through activating NF-κB remains obscure.

METHODS

We used two TSCC cell lines as a cell model to study invasion and EMT in vitro, and used nude mice xenografts model to evaluate metastasis of TSCC cells. Finally, we evaluated the level of pEzrin Tyr353, nuclear p65 and EMT markers in TSCC clinical samples.

RESULTS

Ezrin Tyr353 was phosphorylated through Akt (but not ERK1/2, ROCK1) pathway, and lead to the activation of NF-κB in EGF-treated TSCC cells. Akt and NF-κB inhibitors blocked EGF-induced EMT, and suppressed invasion and migration of TSCC cells. In vivo, silencing Ezrin significantly suppressed EGF-enhanced metastasis of TSCC xenografts. Finally, high levels of expression of pEzrin Tyr353, nuclear p65, vimentin and low level of expression of E-cadherin were correlated with cancer metastasis and poor patient prognosis.

CONCLUSION

Our data suggest that Akt/Ezrin Tyr353/NF-κB pathway regulates EGF-induced EMT and metastasis inTSCC, and Ezrin may serve as a therapeutic target to reverse EMT in tongue cancers and prevent TSCC progression.

REST mediates androgen receptor actions on gene repression and predicts early recurrence of prostate cancer

The androgen receptor (AR) is a key regulator of prostate tumorgenesis through actions that are not fully understood. We identified the repressor element (RE)-1 silencing transcription factor (REST) as a mediator of AR actions on gene repression. Chromatin immunoprecipitation showed that AR binds chromatin regions containing well-characterized cis-elements known to mediate REST transcriptional repression, while cell imaging studies confirmed that REST and AR closely co-localize in vivo. Androgen-induced gene repression also involves modulation of REST protein turnover through actions on the ubiquitin ligase β-TRCP. Androgen deprivation or AR blockage with inhibitor MDV3100 (Enzalutamide) leads to neuroendocrine (NE) differentiation, a phenomenon that is mimicked by REST inactivation. Gene expression profiling revealed that REST not only acts to repress neuronal genes but also genes involved in cell cycle progression, including Aurora Kinase A, that has previously been implicated in the growth of NE-like castration-resistant tumors. The analysis of prostate cancer tissue microarrays revealed that tumors with reduced expression of REST have higher probability of early recurrence, independently of their Gleason score. The demonstration that REST modulates AR actions in prostate epithelia and that REST expression is negatively correlated with disease recurrence after prostatectomy, invite a deeper characterization of its role in prostate carcinogenesis.

SOCS2 mediates the cross talk between androgen and growth hormone signaling in prostate cancer

Anabolic signals such as androgens and the growth hormone/insulin-like growth factor 1 (GH/IGF-1) axis play an essential role in the normal development of the prostate but also in its malignant transformation. In this study, we investigated the role of suppressor of cytokine signaling 2 (SOCS2) as mediator of the cross talk between androgens and GH signals in the prostate and its potential role as tumor suppressor in prostate cancer (PCa). We observed that SOCS2 protein levels assayed by immunohistochemistry are elevated in hormone therapy-naive localized prostatic adenocarcinoma in comparison with benign tissue. In contrast, however, castration-resistant bone metastases exhibit reduced levels of SOCS2 in comparison with localized or hormone naive, untreated metastatic tumors. In PCa cells, SOCS2 expression is induced by androgens through a mechanism that requires signal transducer and activator of transcription 5 protein (STAT5) and androgen receptor-dependent transcription. Consequentially, SOCS2 inhibits GH activation of Janus kinase 2, Src and STAT5 as well as both cell invasion and cell proliferation in vitro. In vivo, SOCS2 limits proliferation and production of IGF-1 in the prostate in response to GH. Our results suggest that the use of GH-signaling inhibitors could be of value as a complementary treatment for castration-resistant PCa.

SUMMARY

Androgen induced SOCS2 ubiquitin ligase expression and inhibited GH signaling as well as cell proliferation and invasion in PCa, whereas reduced SOCS2 was present in castration-resistant cases. GH-signaling inhibitors might be a complementary therapeutic option for advanced PCa.

CIP2A is overexpressed in osteosarcoma and regulates cell proliferation and invasion

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a newly characterized oncoprotein involved in a variety of malignant tumors. However, its expression pattern and biological functions in osteosarcoma remain unclear. In the present study, CIP2A expression was analyzed in 51 human osteosarcoma specimens using immunohistochemistry. CIP2A siRNA was used in the MG-63 cell line, and the effect of CIP2A depletion on cell proliferation and invasion was evaluated. We found that CIP2A was overexpressed in 76.5 % (39/51) of osteosarcoma tissues, while normal bone tissues showed negative CIP2A expression. In addition, the positive rate of CIP2A expression was higher in stage IIB osteosarcoma than stage IIA cases. Knockdown of the CIP2A expression significantly reduced osteosarcoma cell proliferation and invasion, with decreased c-Myc expression and p-AKT expression. CIP2A depletion also facilitated apoptosis and inhibited MMP9 mRNA expression. Taken together, our data identified CIP2A as a critical oncoprotein involved in cell proliferation and invasion, which could serve as a therapeutic target in osteosarcoma.

Sphingolipid regulation of ezrin, radixin, and moesin proteins family: implications for cell dynamics

A key but poorly studied domain of sphingolipid functions encompasses endocytosis, exocytosis, cellular trafficking, and cell movement. Recently, the ezrin, radixin and moesin (ERM) family of proteins emerged as novel potent targets regulated by sphingolipids. ERMs are structural proteins linking the actin cytoskeleton to the plasma membrane, also forming a scaffold for signaling pathways that are used for cell proliferation, migration and invasion, and cell division. Opposing functions of the bioactive sphingolipid ceramide and sphingosine-1-phosphate (S1P), contribute to ERM regulation. S1P robustly activates whereas ceramide potently deactivates ERM via phosphorylation/dephosphorylation, respectively. This recent dimension of cytoskeletal regulation by sphingolipids opens up new avenues to target cell dynamics, and provides further understanding of some of the unexplained biological effects mediated by sphingolipids. In addition, these studies are providing novel inroads into defining basic mechanisms of regulation and action of bioactive sphingolipids. This review describes the current understanding of sphingolipid regulation of the cytoskeleton, it also describes the biologies in which ERM proteins have been involved, and finally how these two large fields have started to converge. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.

Acquired resistance to zoledronic acid and the parallel acquisition of an aggressive phenotype are mediated by p38-MAP kinase activation in prostate cancer cells

The nitrogen-containing bisphosphonates (N-BP) zoledronic acid (ZOL) inhibits osteoclast-mediated bone resorption, and it is used to prevent skeletal complications from bone metastases. ZOL has also demonstrated anticancer activities in preclinical models and, recently, in cancer patients, highlighting the interest in determining eventual mechanisms of resistance against this agent. In our study, we selected and characterised a resistant subline of prostate cancer (PCa) cells to better understand the mechanisms, by which tumour cells can escape the antitumour effect of ZOL. DU145R80-resistant cells were selected in about 5 months using stepwise increasing concentrations of ZOL from DU145 parental cells. DU145R80 cells showed a resistance index value of 5.5 and cross-resistance to another N-BP, pamidronate, but not to the non-nitrogen containing BP clodronate. Notably, compared with DU145 parental cells, DU145R80 developed resistance to apoptosis and anoikis, as well as overexpressed the anti-apoptotic protein Bcl-2 and oncoprotein c-Myc. Moreover, DU145R80 cells underwent epithelial to mesenchymal transition (EMT) and showed increased expression of the metalloproteases MMP-2/9, as well as increased invading capability. Interestingly, compared with DU145, DU145R80 cells also increased the gene expression and protein secretion of VEGF and the cytokines Eotaxin-1 and IL-12. At the molecular level, DU145R80 cells showed strong activation of the p38-MAPK-dependent survival pathway compared with parental sensitive cells. Moreover, using the p38-inhibitor SB203580, we completely reversed the resistance to ZOL, as well as EMT marker expression and invasion. Furthermore, SB203580 treatment reduced the expression of VEGF, Eotaxin-1, IL-12, MMP-9, Bcl-2 and c-Myc. Thus, for the first time, we demonstrate that the p38-MAPK pathway can be activated under continuous extensive exposure to ZOL in PCa cells and that the p38-MAPK pathway has a critical role in the induction of resistance, as well as in the acquisition of a more aggressive and invasive phenotype.

Rho-associated coiled-coil kinase (ROCK) signaling and disease

The small Rho GTPase family of proteins, encompassing the three major G-protein classes Rho, Rac and cell division control protein 42, are key mitogenic signaling molecules that regulate multiple cancer-associated cellular phenotypes including cell proliferation and motility. These proteins are known for their role in the regulation of actin cytoskeletal dynamics, which is achieved through modulating the activity of their downstream effector molecules. The Rho-associated coiled-coil kinase 1 and 2 (ROCK1 and ROCK2) proteins were the first discovered Rho effectors that were primarily established as players in RhoA-mediated stress fiber formation and focal adhesion assembly. It has since been discovered that the ROCK kinases actively phosphorylate a large cohort of actin-binding proteins and intermediate filament proteins to modulate their functions. It is well established that global cellular morphology, as modulated by the three cytoskeletal networks: actin filaments, intermediate filaments and microtubules, is regulated by a variety of accessory proteins whose activities are dependent on their phosphorylation by the Rho-kinases. As a consequence, they regulate many key cellular functions associated with malignancy, including cell proliferation, motility and viability. In this current review, we focus on the role of the ROCK-signaling pathways in disease including cancer.

Ezrin is associated with gastric cancer progression and prognosis

To investigat the clinical significance of Ezrin in the development and progression of gastric cancer. Immunohistochemistry was employed to analyze Ezrin expression in 436 clinicopathologically characterized gastric cancer cases. Ezrin protein levels were up-regulated in gastric cancer lesions compared with adjacent noncancerous tissues. Positive expression of Ezrin correlated with age, size of tumor, location of tumor, depth of invasion, vessel invasion, lymph node and distant metastasis and TNM stage. In stages I, II and III, the 5 year survival rate of patients with a high expression of Ezrin was significantly lower than those in patients with low expression. In stage IV, Ezrin expression did not correlate with the 5 year survival rate. Further multivariate analysis suggested that the depth of invasion, lymph node and distant metastasis, TNM stage, and up-regulation of Ezrin were independent prognostic indicators for the disease. Expression of Ezrin in gastric cancer is significantly associated with lymph node and distant metastasis, and poor prognosis. Ezrin protein could be useful markers to predict tumor progression and prognosis.

Proteomic patterns of cervical cancer cell lines, a network perspective

Background

Cervical cancer is a major mortality factor in the female population. This neoplastic is an excellent model for studying the mechanisms involved in cancer maintenance, because the Human Papilloma Virus (HPV) is the etiology factor in most cases. With the purpose of characterizing the effects of malignant transformation in cellular activity, proteomic studies constitute a reliable way to monitor the biological alterations induced by this disease. In this contextual scheme, a systemic description that enables the identification of the common events between cell lines of different origins, is required to distinguish the essence of carcinogenesis.

Results

With this study, we sought to achieve a systemic perspective of the common proteomic profile of six cervical cancer cell lines, both positive and negative for HPV, and which differ from the profile corresponding to the non-tumourgenic cell line, HaCaT. Our objectives were to identify common cellular events participating in cancer maintenance, as well as the establishment of a pipeline to work with proteomic-derived results. We analyzed by means of 2D SDS-PAGE and MALDI-TOF mass spectrometry the protein extracts of six cervical cancer cell lines, from which we identified a consensus of 66 proteins. We call this group of proteins, the "central core of cervical cancer". Starting from this core set of proteins, we acquired a PPI network that pointed, through topological analysis, to some proteins that may well be playing a central role in the neoplastic process, such as 14-3-3ζ. In silico overrepresentation analysis of transcription factors pointed to the overexpression of c-Myc, Max and E2F1 as key transcription factors involved in orchestrating the neoplastic phenotype.

Conclusions

Our findings show that there is a "central core of cervical cancer" protein expression pattern, and suggest that 14-3-3ζ is key to determine if the cell proliferates or dies. In addition, our bioinformatics analysis suggests that the neoplastic phenotype is governed by a non-canonical regulatory pathway.

Inactivation of AR/TMPRSS2-ERG/Wnt signaling networks attenuates the aggressive behavior of prostate cancer cells

The development of prostate cancer and its progression to castrate-resistant prostate cancer (CRPC) after antiandrogen ablation therapy are driven by persistent biological activity of androgen receptor (AR) signaling. Moreover, studies have shown that more than 50% of human prostate cancers overexpress ERG (v-ets avian erythroblastosis virus E26 oncogene related gene) due to AR-regulated TMPRSS2-ERG fusion gene. However, the reported roles of TMPRSS2-ERG fusion in cancer progression are not clear. In this study, we investigated the signal transduction in the AR/TMPRSS2-ERG/Wnt signaling network for studying the aggressive behavior of prostate cancer cells and further assessed the effects of BR-DIM and CDF [natural agents-derived synthetic formulation and analogue of 3,3'-diindolylmethane (DIM) and curcumin, respectively, with improved bioavailability] on the regulation of AR/TMPRSS2-ERG/Wnt signaling. We found that activation of AR resulted in the induction of ERG expression through TMPRSS2-ERG fusion. Moreover, we found that ERG overexpression and nuclear translocation activated the activity of Wnt signaling. Furthermore, forced overexpression of ERG promoted invasive capacity of prostate cancer cells. More important, we found that BR-DIM and CDF inhibited the signal transduction in the AR/TMPRSS2-ERG/Wnt signaling network, leading to the inactivation of Wnt signaling consistent with inhibition of prostate cancer cell invasion. In addition, BR-DIM and CDF inhibited proliferation of prostate cancer cells and induced apoptotic cell death. On the basis of our findings, we conclude that because BR-DIM and CDF downregulate multiple signaling pathways including AR/TMPRSS2-ERG/Wnt signaling, these agents could be useful for designing novel strategies for the prevention and/or treatment of prostate cancer.

Potential transcriptional regulatory regions exist upstream of the human ezrin gene promoter in esophageal carcinoma cells

We previously demonstrated that the region -87/+134 of the human ezrin gene (VIL2) exhibited promoter activity in human esophageal carcinoma EC109 cells, and a further upstream region -1324/-890 positively regulated transcription. In this study, to identify the transcriptional regulatory regions upstream of the VIL2 promoter, we cloned VIL2 -1541/-706 segment containing the -1324/-890, and investigated its transcriptional regulatory properties via luciferase assays in transiently transfected cells. In EC109 cells, it was found that VIL2 -1541/-706 possessed promoter and enhancer activities. We also localized transcriptional regulatory regions by fusing 5'- or 3'-deletion segments of VIL2 -1541/-706 to a luciferase reporter. We found that there were three positive and one negative transcriptional regulatory regions within VIL2 -1541/-706 in EC109 cells. When these regions were separately located upstream of the luciferase gene without promoter, or located upstream of the VIL2 promoter or SV40 promoter directing the luciferase gene, only VIL2 -1297/-1186 exhibited considerable promoter and enhancer activities, which were lower than those of -1541/-706. In addition, transient expression of Sp1 increased ezrin expression and the transcriptional activation of VIL2 -1297/-1186. Other three regions, although exhibiting significantly positive or negative transcriptional regulation in deletion experiments, showed a weaker or absent regulation. These data suggested that more than one region upstream of the VIL2 promoter participated in VIL2 transcription, and the VIL2 -1297/-1186, probably as a key transcriptional regulatory region, regulated VIL2 transcription in company with other potential regulatory regions.

Expression of the membrane-cytoskeletal linker Ezrin in salivary gland adenoid cystic carcinoma

OBJECTIVE

The aim of this study was to investigate the relationship between membrane cytoskeleton linker protein Ezrin and CD44v6, iNOS, Ki-67, and clinicopathologic characteristics, and the prognostic significance of Ezrin expression in salivary gland adenoid cystic carcinoma (SACC).

STUDY DESIGN

Immunohistochemistry and reverse-transcription polymerase chain reaction were used to quantify the expression of Ezrin, CD44v6, inducible nitric oxide synthase (iNOS), and Ki-67 in 75 primary SACCs, 25 tumor-free salivary tissues, and 2 SACC cell lines (ACC-M and ACC-2). Survival analysis was performed to find the prognostic significance of Ezrin expression.

RESULTS

Expressions of Ezrin, CD44v6, iNOS, and Ki-67 in SACC tissues, especially with distant metastasis, were significantly higher than in tumor-free tissues. Ezrin mRNA and protein levels in ACC-M cells were significantly higher than in ACC-2 cells. Ezrin, CD44v6, iNOS, and Ki-67 expressions were significantly higher in solid pattern than in cribriform and tubular patterns. Ezrin and its partners, CD44v6, iNOS, and Ki-67, were significantly related to tumor size, clinical stage, perineural and vascular invasion, and recurrence. Furthermore, Ezrin had an independent prognostic effect on overall survival.

CONCLUSIONS

The increased expression of Ezrin and its partners, CD44v6, iNOS, and Ki-67, in SACC correlated with histologic patterns, may play a role in distant metastasis, and might indicate poor clinical outcome.