Role of the EphB2 receptor in autophagy, apoptosis and invasion in human breast cancer cells

Silencing EPHB2 diminished the malignant biological properties of esophagus cancer cells by blocking autophagy and Wnt/β-catenin pathway

Eph receptor B2 (EPHB2) is overexpressed in some tumors and relevant to unfavorable outcomes of tumor patients. By searching Gene Expression Profiling Interactive Analysis and KM Plot websites, we discovered that EPHB2 was highly expressed in patients with esophageal cancer, leading to poor prognosis. However, the role and molecular mechanism of EPHB2 in esophagus cancer is unknown. Our study aims to unveil the underlying mechanism by which EPHB2 modulates the biological properties of esophagus cancer cells. After si-EPHB2 transfection, the malignant biological properties of esophagus cancer cells were determined by several biological experiments. IWP-4 was applied to block Wnt/β-catenin signaling pathway. The expressions of autophagy and Wnt/β-catenin signaling pathway relevant molecules were tested by western blot assay. An increased expression of EPHB2 was happened in esophagus cancer samples and loss of EPHB2 diminished esophagus cancer cells proliferation, migration, and invasion. Moreover, our data showed that depletion of EPHB2 blocked the autophagy and in-activated Wnt/β-catenin signaling pathway in esophagus cancer cells. While, IWP-4 treatment inhibited the autophagy and limited esophagus cancer cells proliferation, migration, and invasion. Moreover, EPHB2 knocked down strengthened the effect of IWP-4 treatment in regulating esophagus cancer cells proliferation, migration, and invasion. Finally, we illustrated that EPHB2 regulated the biological properties of esophagus cancer cells by modulating autophagy and Wnt/β-catenin signaling pathway. Our study illustrated that EPHB2 might be a worthwhile target considering for the treatment of esophagus cancer.

Ephrin B2 (EFNB2) potentially protects against intervertebral disc degeneration through inhibiting nucleus pulposus cell apoptosis

Nucleus pulposus (NP) cell apoptosis is a significant indication of accelerated intervertebral disc degeneration; however, the precise mechanism is unelucidated as of yet. Ephrin B2 (EFNB2), the only gene down-regulated in the three degraded intervertebral disc tissue microarray groups (GSE70362, GSE147383 and GSE56081), was screened for examination in this study. Subsequently, EFNB2 was verified to be down-regulated in degraded NP tissue samples. Interleukin-1 (IL-1β) treatment of NP cells to simulate the IDD environment indicated that IL-1β treatment decreased EFNB2 expression. In degenerative NP cells stimulated by IL-1β, EFNB2 knockdown significantly increased the rate of apoptosis as well as the apoptosis-related molecules cleaved-caspase-3 and the Bax to Bcl-2 ratio. EFNB2 was found to promote AKT, PI3K, and mTOR phosphorylation; the PI3K/AKT signaling role was investigated using the PI3K inhibitor LY294002. EFNB2 overexpression significantly increased PI3K/AKT pathway activity in IL-1β-stimulated NP cells than the normal control. Moreover, EFNB2 partially alleviated NP cell apoptosis induced by IL-1β, reduced the cleaved-cas3 level, and decreased the Bax/Bcl-2 ratio after the addition of the inhibitor LY294002. Additionally, EFNB2 overexpression inhibited the ERK1/2 phosphorylation; the effects of EFNB2 overexpression on ERK1/2 phosphorylation, degenerative NP cell viability, and cell apoptosis were partially reversed by ERK signaling activator Ceramide C6. EFNB2 comprehensively inhibited the apoptosis of NP cells by activating the PI3K/AKT signaling and inhibiting the ERK signaling, obviating the exacerbation of IDD. EFNB2 could be a potential target to protect against degenerative disc changes.

An investigation of binding interactions of tumor-targeted peptide conjugated polyphenols with the kinase domain of ephrin B4 and B2 receptors

Recent studies have shown that Ephrin receptors may be upregulated in several types of cancers including breast, ovarian and endometrial cancers, making them a target for drug design. In this work, we have utilized a target-hopping approach to design new natural product-peptide conjugates and examined their interactions with the kinase-binding domain of EphB4 and EphB2 receptors. The peptide sequences were generated through point mutations of the known EphB4 antagonist peptide TNYLFSPNGPIA. Their anticancer properties and secondary structures were analyzed computationally. Conjugates of most optimum of peptides were then designed by binding the N-terminal of the peptides with the free carboxyl group of the polyphenols sinapate, gallate and coumarate, which are known for their inherent anticancer properties. To investigate if these conjugates have a potential to bind to the kinase domain, we carried out docking studies and MMGBSA free energy calculations of the trajectories based on the molecular dynamics simulations, with both the apo and the ATP bound kinase domains of both receptors. In most cases binding interactions occurred within the catalytic loop region, while in some cases the conjugates were found to spread out across the N-lobe and the DFG motif region. The conjugates were further tested for prediction of pharmacokinetic properties using ADME studies. Our results indicated that the conjugates were lipophilic and MDCK permeable with no CYP interactions. These findings provide an insight into the molecular interactions of these peptides and conjugates with the kinase domain of the EphB4 and EphB2 receptor. As a proof of concept, we synthesized and carried out SPR analysis with two of the conjugates (gallate-TNYLFSPNGPIA and sinapate-TNYLFSPNGPIA). Results indicated that the conjugates showed higher binding with the EphB4 receptor and minimal binding to EphB2 receptor. Sinapate-TNYLFSPNGPIA showed inhibitory activity against EphB4. These studies reveal that some of the conjugates may be developed for further investigation into in vitro and in vivo studies and potential development as therapeutics.

Cell Death, by Any Other Name…

Studies trying to understand cell death, this ultimate biological process, can be traced back to a century ago. Yet, unlike many other fashionable research interests, research on cell death is more alive than ever. New modes of cell death are discovered in specific contexts, as are new molecular pathways. But what is "cell death", really? This question has not found a definitive answer yet. Nevertheless, part of the answer is irreversibility, whereby cells can no longer recover from stress or injury. Here, we identify the most distinctive features of different modes of cell death, focusing on the executive final stages. In addition to the final stages, these modes can differ in their triggering stimulus, thus referring to the initial stages. Within this framework, we use a few illustrative examples to examine how intercellular communication factors in the demise of cells. First, we discuss the interplay between cell-cell communication and cell death during a few steps in the early development of multicellular organisms. Next, we will discuss this interplay in a fully developed and functional tissue, the gut, which is among the most rapidly renewing tissues in the body and, therefore, makes extensive use of cell death. Furthermore, we will discuss how the balance between cell death and communication is modified during a pathological condition, i.e., colon tumorigenesis, and how it could shed light on resistance to cancer therapy. Finally, we briefly review data on the role of cell-cell communication modes in the propagation of cell death signals and how this has been considered as a potential therapeutic approach. Far from vainly trying to provide a comprehensive review, we launch an invitation to ponder over the significance of cell death diversity and how it provides multiple opportunities for the contribution of various modes of intercellular communication.

Interaction between the EPHB2 receptor and EFNB1 ligand drives gastric cancer invasion and metastasis via the Wnt/β-catenin/FAK pathway

The survival benefit for patients with gastric cancer (GC) is modest due to its high transfer potential. Targeted therapy for metastasis-related genes in GC may be a viable approach, however, inhibitors specifically targeting GC are limited. In this study, GC patient-derived xenografts (PDX) with metastatic burden were established via orthotopic transplantation. PCR-Array analysis of primary and metastatic tumors revealed EPH receptor B2 (EPHB2) as the most significantly upregulated gene. The interaction between the EPHB2 receptor and its cognate-specific EFNB1 ligands was high in GC and correlated with a poor prognosis. Fc-EFNB1 treatment increased the invasion and migration abilities of GC cells and induced a high EPHB2 expression. EPHB2 knockdown in GC cells completely abolished the ephrin ligand-induced effects on invasion and migration abilities. Signal transduction analysis revealed Wnt/β-catenin and FAK as downstream signaling mediators potentially inducing the EPHB2 phenotype. In conclusion, the observed deregulation of EPHB2/EFNB1 expression in GC enhances the invasive phenotype, suggesting a potential role of EPHB2/EFNB1 compound in local tumor cell invasion and the formation of metastasis.

Eph receptors and ephrins in cancer progression

Evidence implicating Eph receptor tyrosine kinases and their ephrin ligands (that together make up the 'Eph system') in cancer development and progression has been accumulating since the discovery of the first Eph receptor approximately 35 years ago. Advances in the past decade and a half have considerably increased the understanding of Eph receptor-ephrin signalling mechanisms in cancer and have uncovered intriguing new roles in cancer progression and drug resistance. This Review focuses mainly on these more recent developments. I provide an update on the different mechanisms of Eph receptor-ephrin-mediated cell-cell communication and cell autonomous signalling, as well as on the interplay of the Eph system with other signalling systems. I further discuss recent advances in elucidating how the Eph system controls tumour expansion, invasiveness and metastasis, supports cancer stem cells, and drives therapy resistance. In addition to functioning within cancer cells, the Eph system also mediates the reciprocal communication between cancer cells and cells of the tumour microenvironment. The involvement of the Eph system in tumour angiogenesis is well established, but recent findings also demonstrate roles in immune cells, cancer-associated fibroblasts and the extracellular matrix. Lastly, I discuss strategies under evaluation for therapeutic targeting of Eph receptors-ephrins in cancer and conclude with an outlook on promising future research directions.

Role of EphB2/ephrin‑B1 signalling in the development and progression of obesity‑associated colorectal cancer

Obesity is a major problem worldwide and has been associated with colorectal cancer development, among other diseases. Ephrin receptors and ligands play an important role in the turnover of the intestinal mucosa and intestinal crypt compartmentalization. It has been hypothesised that obesity-induced inflammation affects ephrin signals, leading to carcinogenesis. Therefore, the aim of the present study was to assess the relationship between Eph-ephrin B signalling, obesity and obesity-associated colorectal cancer. An azoxymethane-induced obesity-associated cancer KKAy mouse model developed in our prior study was used. A total of 46 patients with consecutive colorectal cancer and 48 tumours were analysed. Immunohistological analyses were performed in mouse and human samples, and immunoreactive scores (IRS) were determined. KKAy mice were significantly more prone to cancer development compared with control C57/BL mice (2/15 in C57/BL vs. 10/10 in KKAy; P<0.001). TUNEL assay revealed a lower number of apoptotic cells in normal mucosa of KKAy mice (8.8% in C57/BL vs. 3.2% in KKAy; P<0.001) and obese patients (9.2% with BMI <25 vs. 3.6% with BMI ≥25; P=0.021). Immunohistological analysis revealed that ephrin-B1 was downregulated in normal mucosa from KKAy mice and obese patients (IRS, 2.86 with BMI <25 vs. 6.00 with BMI ≥25; P=0.002). Moreover, EphB2 was downregulated in tumours from KKAy mice and obese patients (IRS, 6.58 with BMI <25 vs. 3.83 with BMI ≥25; P<0.001). The distribution of infiltrated macrophages corresponded to the MCP-1 expression pattern in KKAy mice, and the number of macrophages was also significantly higher in those mice (36.3 in C57/BL vs. 120.0 in KKAy; P=0.029). The findings suggested that obesity results in disruption of EphB2/ephrin-B1 signalling, promoting colorectal cancer development and progression.

Laminar shear stress inhibits inflammation by activating autophagy in human aortic endothelial cells through HMGB1 nuclear translocation

Prevention and treatment of atherosclerosis (AS) by targeting the inflammatory response in vascular endothelial cells has attracted much attention in recent years. Laminar shear stress (LSS) has well-recognized anti-AS properties, however, the exact molecular mechanism remains unclear. In this study, we found that LSS could inhibit the increased expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), cyclooxygenase-2 (COX-2), and matrix metallopeptidase-9 (MMP-9) caused by TNF-α in an autophagy-dependent pathway in human aortic endothelial cells (HAECs) and human umbilical vein endothelial cells (HUVECs). Whole-transcriptome sequencing analysis revealed that erythropoietin-producing hepatocyte receptor B2 (EPHB2) was a key gene in response to LSS. Moreover, co-immunoprecipitation assay indicated that LSS could enhance the EPHB2-mediated nuclear translocation of high mobility group box-1 (HMGB1), which interacts with Beclin-1 (BECN1) and finally leads to autophagy. Simultaneously, we identified an LSS-sensitive long non-coding RNA (lncRNA), LOC10798635, and constructed an LSS-related LOC107986345/miR-128-3p/EPHB2 regulatory axis. Further research revealed the anti-inflammatory effect of LSS depends on autophagy activation resulting from the nuclear translocation of HMGB1 via the LOC107986345/miR-128-3p/EPHB2 axis. Our study demonstrates that LSS could regulate the expression of EPHB2 in HAECs, and the LOC107986345/miR-128-3p/EPHB2 axis plays a vital role in AS development.

Epigenetic Determinants of Racial Disparity in Breast Cancer: Looking beyond Genetic Alterations

Simple Summary

A substantial disparity in breast cancer incidence and mortality exists between African American (AA) and European American (EA) women. However, the basis for these disparities is poorly understood. In this article, we describe that gene–environment interactions mediated through epigenetic modifications may play a significant role in racial disparities in BC incidence and outcomes. Our in silico analyses and an in-depth literature survey suggest that there exists a significant difference in epigenetic patterns between AA and EA women with breast cancer. Herein, we describe the environmental factors that contribute to these epigenetic changes, which may underlie the disparate racial burden in patients with breast cancer. We suggest that AA women with higher basal epigenetic changes, may have higher pre-disposition to cancer onset, and an aggressive disease course. Pre-existing racial differences in epigenetic profiles of breast tissues raises the possibility of examining these profiles for early diagnosis.

Abstract

Breast cancer (BC) is the most commonly diagnosed cancer in women. Despite advancements in BC screening, prevention, and treatment, BC incidence and mortality remain high among African American (AA) women. Compared with European American (EA) women, AA women tend to be diagnosed with more advanced and aggressive tumors and exhibit worse survival outcomes. Most studies investigating the determinants of racial disparities in BC have focused on genetic factors associated with African ancestry. However, various environmental and social stressors over an individual’s life course can also shape racial stratification in BC. These social and environmental exposures result in long-term changes in gene expression mediated by epigenetic mechanisms. Epigenetics is often portrayed as an intersection of socially patterned stress and genetic expression. The enduring nature of epigenetic changes makes them suitable for studying the effects of different environmental exposures over an individual’s life course on gene expression. The role of differential social and environmental exposures in racial disparities in BC suggests varied epigenetic profiles or signatures associated with specific BC subtypes in AA and EA women. These epigenetic profiles in EA and AA women could be used as biomarkers for early BC diagnosis and disease prognosis and may prove valuable for the development of targeted therapies for BC. This review article discusses the current state of knowledge regarding epigenetic differences between AA and EA women with BC. We also discuss the role of socio-environmental factors, including psychosocial stress, environmental toxicants, and dietary factors, in delineating the different epigenetic profiles in AA and EA patients with BC.

The Roles of EphB2 in Cancer

The erythropoietin-producing hepatocellular carcinoma (Eph) receptors and their Eph receptor-interacting (ephrin) ligands together constitute a vital cell communication system with diverse roles. Experimental evidence revealed Eph receptor bidirectional signaling with both tumor-promoting and tumor-suppressing activities in different cancer types and surrounding environment. Eph receptor B2 (EphB2), an important member of the Eph receptor family, has been proved to be aberrantly expressed in many cancer types, such as colorectal cancer, gastric cancer and hepatocellular carcinoma, resulting in tumor occurrence and progression. However, there are no reviews focusing on the dual roles of EphB2 in cancer. Thus, in this paper we systematically summarize and discuss the roles of EphB2 in cancer. Firstly, we review the main biological features and the related signaling regulatory mechanisms of EphB2, and then we summarize the roles of EphB2 in cancer through current studies. Finally, we put forward our viewpoint on the future prospects of cancer research focusing on EphB2, especially with regard to the effects of EphB2 on tumor immunity.

Ephrin Receptors (Ephs) Expression in Thymic Epithelial Tumors: Prognostic Implications and Future Therapeutic Approaches

Ephrin receptors (Ephs) are receptor tyrosine kinases (RTKs) implicated in tissue development and homeostasis, and they are aberrantly expressed in tumors. Here, immunohistochemical Eph type-A and -B expression in thymic epithelial tumors (TETs) was assessed and correlated with clinicopathological parameters. Tissue microarrays from 98 TETs were stained for EphA1, -A2, -A4 -A6, -B1, -B2, -B4 and -B6. The relationship between neoplastic and lymphoid cell immunoreactivity score (H-score), histopathological parameters (Pearson’s test) and survival of 35 patients (Mantel-Cox model) was explored. Epithelial-rich subtypes showed higher EphA6 cytoplasmic H-score (B2/B3, carcinoma) (p < 0.001) and stronger EphA4 H-score (B3, carcinoma) (p = 0.011). The immature T-cells, especially in subtypes AB/B1, had higher EphB6 H-score than carcinoma-associated mature lymphocytes (p < 0.001); carcinomas had higher lymphocytic EphB1 H-score (p = 0.026). Higher lymphocytic and lower epithelial EphB6 H-score correlated with Masaoka stage ≤II (p = 0.043, p = 0.010, respectively). All cases showed variable epithelial and lymphocytic EphA2 expression, but clinicopathological associations were not reached. Our study confirmed that Eph type-A and -B expression in TETs is associated with established prognostic parameters, i.e., tumor subtype and Masaoka stage, although correlation with patient survival was not reached. Such findings suggest involvement of these RTKs in thymic neoplasia, as well as their potential utility as treatment targets.

The Value of EphB2 Receptor and Cognate Ephrin Ligands in Prognostic and Predictive Assessments of Human Breast Cancer

Cell–cell communication proteins Eph and ephrin constitute the largest family of receptor tyrosine kinases (RTKs). They are distinguished by the fact that both receptors and ligands are membrane-bound, and both can drive intracellular signaling in their respective cells. Ever since these RTKs have been found to be involved in cancer development, strategies to target them therapeutically have been actively pursued. However, before this goal can be rationally achieved, the contributions of either Eph receptors or their ephrin ligands to cancer development and progression should be scrutinized in depth. To assess the clinical pertinence of this concern, we performed a systematic review and meta-analysis of the prognostic/predictive value of EphB2 and its multiple cognate ephrin ligands in breast cancer. We found that EphB2 has prognostic value, as indicated by the association of higher EphB2 expression levels with lower distant metastasis-free survival (DMFS), and the association of lower EphB2 expression levels with poorer relapse-free survival (RFS). We also found that higher EphB2 expression could be a prognostic factor for distant metastasis, specifically in the luminal subtypes of breast cancer. EFNB2 showed a marked correlation between higher expression levels and shorter DMFS. EFNA5 or EFNB1 overexpression is correlated with longer RFS. Increased EFNB1 expression is correlated with longer OS in lymph node (LN)-negative patients and the luminal B subtype. Higher levels of EFNB2 or EFNA5 are significantly correlated with shorter RFS, regardless of LN status. However, while this correlation with shorter RFS is true for EFNB2 in all subtypes except basal, it is also true for EFNA5 in all subtypes except HER2+. The analysis also points to possible predictive value for EphB2. In systemically treated patients who have undergone either endocrine therapy or chemotherapy, we found that higher expression of EphB2 is correlated with better rates of RFS. Bearing in mind the limitations inherent to any mRNA-based profiling method, we complemented our analysis with an immunohistochemical assessment of expression levels of both the EphB2 receptor and cognate ephrin ligands. We found that the latter are significantly more expressed in cancers than in normal tissues, and even more so in invasive and metastatic samples than in ductal carcinoma in situ (DCIS). Finally, in an in vitro cellular model of breast cancer progression, based on H-Ras-transformation of the MCF10A benign mammary cell line, we observed dramatic increases in the mRNA expression of EphB2 receptor and EFNB1 and EFNB2 ligands in transformed and invasive cells in comparison with their benign counterparts. Taken together, these data show the clinical validity of a model whereby EphB2, along with its cognate ephrin ligands, have dual anti- and pro-tumor progression effects. In so doing, they reinforce the necessity of further biological investigations into Ephs and ephrins, prior to using them in targeted therapies.

A live single-cell reporter assay links intratumor heterogeneity to metastatic proclivity in Ewing sarcoma

Targeting of the most aggressive tumor cell subpopulations is key for effective management of most solid malignancies. However, the metastable nature of tumor heterogeneity, which allows cells to transition between strong and weak tumorigenic phenotypes, and the lack of reliable markers of tumor-promoting properties hamper identification of the most relevant cells. To overcome these obstacles, we designed a functional microRNA (miR)-based live-cell reporter assay to identify highly tumorigenic cells in xenotransplants of primary Ewing sarcoma (EwS) 3D cultures. Leveraging the inverse relationship between cell pluripotency and miR-145 expression, we successfully separated highly tumorigenic, metastasis-prone (miR-145low) cells from poorly tumorigenic, nonmetastatic (miR-145high) counterparts. Gene expression and functional studies of the two cell populations identified the EPHB2 receptor as a prognostic biomarker in patients with EwS and a major promoter of metastasis. Our study provides a simple and powerful means to identify and isolate tumor cells that display aggressive behavior.

Ciliogenesis and autophagy are coordinately regulated by EphA2 in the cornea to maintain proper epithelial architecture

PURPOSE

To understand the relationship between ciliogenesis and autophagy in the corneal epithelium.

METHODS

siRNAs for EphA2 or PLD1 were used to inhibit protein expression in vitro. Morpholino-anti-EphA2 was used to knockdown EphA2 in Xenopus skin. An EphA2 knockout mouse was used to conduct loss of function studies. Autophagic vacuoles were visualized by contrast light microscopy. Autophagy flux, was measured by LC3 turnover and p62 protein levels. Immunostaining and confocal microscopy were conducted to visualize cilia in cultured cells and in vivo.

RESULTS

Loss of EphA2 (i) increased corneal epithelial thickness by elevating proliferative potential in wing cells, (ii) reduced the number of ciliated cells, (iii) increased large hollow vacuoles, that could be rescued by BafA1; (iv) inhibited autophagy flux and (v) increased GFP-LC3 puncta in the mouse corneal epithelium. This indicated a role for EphA2 in stratified epithelial assembly via regulation of proliferation as well as a positive role in both ciliogenesis and end-stage autophagy. Inhibition of PLD1, an EphA2 interacting protein that is a critical regulator of end-stage autophagy, reversed the accumulation of vacuoles, and the reduction in the number of ciliated cells due to EphA2 depletion, suggesting EphA2 regulation of both end-stage autophagy and ciliogenesis via PLD1. PLD1 mediated rescue of ciliogenesis by EphA2 depletion was blocked by BafA1, placing autophagy between EphA2 signaling and regulation of ciliogenesis.

CONCLUSION

Our findings demonstrate a novel role for EphA2 in regulating both autophagy and ciliogenesis, processes that are essential for proper corneal epithelial homeostasis.

Prognostic Significance of Autophagy-Relevant Gene Markers in Colorectal Cancer

Background

Colorectal cancer (CRC) is a common malignant solid tumor with an extremely low survival rate after relapse. Previous investigations have shown that autophagy possesses a crucial function in tumors. However, there is no consensus on the value of autophagy-associated genes in predicting the prognosis of CRC patients. This work screens autophagy-related markers and signaling pathways that may participate in the development of CRC, and establishes a prognostic model of CRC based on autophagy-associated genes.

Methods

Gene transcripts from the TCGA database and autophagy-associated gene data from the GeneCards database were used to obtain expression levels of autophagy-associated genes, followed by Wilcox tests to screen for autophagy-related differentially expressed genes. Then, 11 key autophagy-associated genes were identified through univariate and multivariate Cox proportional hazard regression analysis and used to establish prognostic models. Additionally, immunohistochemical and CRC cell line data were used to evaluate the results of our three autophagy-associated genes EPHB2, NOL3, and SNAI1 in TCGA. Based on the multivariate Cox analysis, risk scores were calculated and used to classify samples into high-risk and low-risk groups. Kaplan-Meier survival analysis, risk profiling, and independent prognosis analysis were carried out. Receiver operating characteristic analysis was performed to estimate the specificity and sensitivity of the prognostic model. Finally, GSEA, GO, and KEGG analysis were performed to identify the relevant signaling pathways.

Results

A total of 301 autophagy-related genes were differentially expressed in CRC. The areas under the 1-year, 3-year, and 5-year receiver operating characteristic curves of the autophagy-based prognostic model for CRC were 0.764, 0.751, and 0.729, respectively. GSEA analysis of the model showed significant enrichment in several tumor-relevant pathways and cellular protective biological processes. The expression of EPHB2, IL-13, MAP2, RPN2, and TRAF5 was correlated with microsatellite instability (MSI), while the expression of IL-13, RPN2, and TRAF5 was related to tumor mutation burden (TMB). GO analysis showed that the 11 target autophagy genes were chiefly enriched in mRNA processing, RNA splicing, and regulation of the mRNA metabolic process. KEGG analysis showed enrichment mainly in spliceosomes. We constructed a prognostic risk assessment model based on 11 autophagy-related genes in CRC.

Conclusion

A prognostic risk assessment model based on 11 autophagy-associated genes was constructed in CRC. The new model suggests directions and ideas for evaluating prognosis and provides guidance to choose better treatment strategies for CRC.

Genetic knockdown of Klk8 has sex-specific multi-targeted therapeutic effects on Alzheimer's pathology in mice

AIMS

Previous work in our lab has identified the protease kallikrein-8 (KLK8) as a potential upstream mover in the pathogenesis of Alzheimer's disease (AD). We showed pathologically elevated levels of KLK8 in the cerebrospinal fluid and blood of patients with mild cognitive impairment or dementia due to AD, and in brains of patients and transgenic CRND8 (TgCRND8) mice in incipient stages of the disease. Furthermore, short-term antibody-mediated KLK8 inhibition in moderate stage disease alleviated AD pathology in female mice. However, it remains to be shown whether long-term reversal of KLK8 overexpression can also counteract AD. Therefore, the effects of genetic Klk8-knockdown were determined in TgCRND8 mice.

METHODS

The effects of heterozygous ablation of murine Klk8 (mKlk8) gene on AD pathology of both sexes were examined by crossbreeding TgCRND8 [hAPP+/-] with mKlk8-knockdown [mKlk8+/-] mice resulting in animals with or without AD pathology which revealed pathologically elevated or normal KLK8 levels.

RESULTS

mKlk8-knockdown had negligible effects on wildtype animals but led to significant decline of amyloid beta (Aβ) and tau pathology as well as an improvement of structural neuroplasticity in a sex-specific manner in transgenics. These changes were mediated by a shift to non-amyloidogenic cleavage of the human amyloid precursor protein (APP), recovery of the neurovascular unit and maintaining microglial metabolic fitness. Mechanistically, Klk8-knockdown improved Aβ phagocytosis in primary glia and Aβ resistance in primary neurons. Most importantly, transgenic mice revealed less anxiety and a better memory performance.

CONCLUSIONS

These results reinforce the potential of KLK8 as a therapeutic target in AD.

The Role of the Eph Receptor Family in Tumorigenesis

Simple Summary

The Eph receptor family is implicated in both tumour promotion and suppression, depending on the tissue-specific context of available receptor interactions with ligands, adaptor proteins and triggered downstream signalling pathways. This complex interplay has not only consequences for tumorigenesis but also offers a basis from which new cancer-targeting strategies can be developed. This review comprehensively summarises the current knowledge of Eph receptor implications in oncogenesis in a tissue- and receptor-specific manner, with the aim to develop a better understanding of Eph signalling pathways for potential targeting in novel cancer therapies.

Abstract

The Eph receptor tyrosine kinase family, activated by binding to their cognate ephrin ligands, are important components of signalling pathways involved in animal development. More recently, they have received significant interest due to their involvement in oncogenesis. In most cases, their expression is altered, affecting the likes of cell proliferation and migration. Depending on the context, Eph receptors have the potential to act as both tumour promoters and suppressors in a number of cancers, such as breast cancer, colorectal cancer, lung cancer, prostate cancer, brain cancer and Kaposi’s sarcoma (KS), the latter being intrinsically linked to EphA2 as this is the receptor used for endothelial cell entry by the Kaposi’s sarcoma-associated herpesvirus (KSHV). In addition, EphA2 deregulation is associated with KS, indicating that it has a dual role in this case. Associations between EphA2 sequence variation and KSHV infection/KS progression have been detected, but further work is required to formally establish the links between EphA2 signalling and KS oncogenesis. This review consolidates the available literature of the role of the Eph receptor family, and particularly EphA2, in tumorigenesis, with the aim to develop a better understanding of Eph signalling pathways for potential targeting in novel cancer therapies.

RNF186 regulates EFNB1 (ephrin B1)-EPHB2-induced autophagy in the colonic epithelial cells for the maintenance of intestinal homeostasis

Although genome-wide association studies have identified the gene RNF186 encoding an E3 ubiquitin-protein ligase as conferring susceptibility to ulcerative colitis, the exact function of this protein remains unclear. In the present study, we demonstrate an important role for RNF186 in macroautophagy/autophagy activation in colonic epithelial cells and intestinal homeostasis. Mechanistically, RNF186 acts as an E3 ubiquitin-protein ligase for EPHB2 and regulates the ubiquitination of EPHB2. Upon stimulation by ligand EFNB1 (ephrin B1), EPHB2 is ubiquitinated by RNF186 at Lys892, and further recruits MAP1LC3B for autophagy. Compared to control mice, rnf186^-/- and ephb2^-/- mice have a more severe phenotype in the DSS-induced colitis model, which is due to a defect in autophagy in colon epithelial cells. More importantly, treatment with ephrin-B1-Fc recombinant protein effectively relieves DSS-induced mouse colitis, which suggests that ephrin-B1-Fc may be a potential therapy for human inflammatory bowel diseases.Abbreviations: ACTB: actin beta; ATG5: autophagy related 5; ATG16L1: autophagy related 16 like 1; ATP: adenosine triphosphate; Cas9: CRISPR associated protein 9; CD: Crohn disease; CQ: chloroquine; Csf2: colony stimulating factor 2; Cxcl1: c-x-c motif chemokine ligand 1; DMSO: dimethyl sulfoxide; DSS: dextran sodium sulfate; EFNB1: ephrin B1; EPHB2: EPH receptor B2; EPHB3: EPH receptor B3; EPHB2^K788R: lysine 788 mutated to arginine in EPHB2; EPHB2^K892R: lysine 892 mutated to arginine in EPHB2; ER: endoplasmic reticulum; FITC: fluorescein isothiocyanate; GFP: green fluorescent protein; GWAS: genome-wide association studies; HRP: horseradish peroxidase; HSPA5/BiP: heat shock protein family A (Hsp70) member 5; IBD: inflammatory bowel diseases; Il1b: interleukin 1 beta; Il6: interleukin 6; IRGM:immunity related GTPase M; i.p.: intraperitoneally; IPP: inorganic pyrophosphatase; KD: knockdown; KO: knockout; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MTOR: mechanistic target of rapamycin kinase; NOD2: nucleotide binding oligomerization domain containing 2; PI3K: phosphoinositide 3-kinase; PtdIns3K: class III phosphatidylinositol 3-kinase; RNF186: ring finger protein 186; RNF186^A64T: alanine 64 mutated to threonine in RNF186; RNF186^R179X: arginine 179 mutated to X in RNF186; RPS6: ribosomal protein S6; Tnf: tumor necrosis factor; SQSTM1: sequestosome 1; Ub: ubiquitin; UBE2D2: ubiquitin conjugating enzyme E2 D2; UBE2H: ubiquitin conjugating enzyme E2 H; UBE2K: ubiquitin conjugating enzyme E2 K; UBE2N: ubiquitin conjugating enzyme E2 N; UC: ulcerative colitis; ULK1:unc-51 like autophagy activating kinase 1; WT: wild type.

Kinome scale profiling of venom effects on cancer cells reveals potential new venom activities

The search for novel and relevant cancer therapeutics is continuous and ongoing. Cancer adaptations, resulting in therapeutic treatment failures, fuel this continuous necessity for new drugs to novel targets. Recently, researchers have started to investigate the effect of venoms and venom components on different types of cancer, investigating their mechanisms of action. Receptor tyrosine kinases (RTKs) comprise a family of highly conserved and functionally important druggable targets for cancer therapy. This research exploits the novelty of complex venom mixtures to affect phosphorylation of the epidermal growth factor receptor (EGFR) and related RTK family members, dually identifying new activities and unexplored avenues for future cancer and venom research. Six whole venoms from diverse species taxa, were evaluated for their ability to illicit changes in the phosphorylated expression of a panel of 49 commonly expressed RTKs. The triple negative breast cancer cell line MDA-MB-468 was treated with optimised venom doses, pre-determined by SDS PAGE and Western blot analysis. The phosphorylated expression levels of 49 RTKs in response to the venoms were assessed with the use of Human Phospho-RTK Arrays and analysed using ImageLab 5.2.1 analysis software (BioRad). Inhibition of EGFR phosphorylation occurred with treatment of venom from Acanthoscurria geniculata (Theraphosidae), Heterometrus swammerdami (Scorpionidae), Crotalus durissus vegrandis (Crotalidae) and Naja naja (Elapidae). Western green mamba Dendroaspis viridis venom increased EGFR phosphorylation. Eph, HGFR and HER were the most affected receptor families by venoms. Whilst the importance of these changes in terms of effect on MDA-MB-468 cells' long-term viability and functionality are still unclear, the findings present exciting opportunities for further investigation as potential drug targets in cancer and as tools to understand better how these pathways interact.

The role of Eph receptors in cancer and how to target them: novel approaches in cancer treatment

INTRODUCTION

Erythropoietin-producing human hepatocellular (Eph) receptors are among the largest family of tyrosine kinases that are divided into two classes: EphA and EphB receptors. Over the past two decades, their role in cancer has become more evident.

AREAS COVERED

There is a need for new anticancer treatments and more insight in the emerging role of Eph receptors in cancer. Molecular mechanisms underlying the pro-tumorigenic effects of Eph receptors could be exploited for future therapeutic strategies. This review describes the variability in expression levels and different effects on oncogenic and tumor suppressive downstream signaling of Eph receptors in various cancer types, and the small molecules, antibodies and peptides that target these receptors.

EXPERT OPINION

The complexity of Eph signaling is a challenge for the definition of clear targets for cancer treatment. Nevertheless, numerous drugs that target EphA2 and EphB4 are currently in clinical trials. However, some Eph targeted drugs also inhibit other tyrosine kinases, so it is unclear to what extent the targeting of Eph receptors contributes to their efficacy. Future research is warranted for an improved understanding of the full network in which Eph receptors function. This will be critical for the improvement of the anticancer effects of drugs that target the Eph receptors.

Tumor microenvironment complexity and therapeutic implications at a glance

The dynamic interactions of cancer cells with their microenvironment consisting of stromal cells (cellular part) and extracellular matrix (ECM) components (non-cellular) is essential to stimulate the heterogeneity of cancer cell, clonal evolution and to increase the multidrug resistance ending in cancer cell progression and metastasis. The reciprocal cell-cell/ECM interaction and tumor cell hijacking of non-malignant cells force stromal cells to lose their function and acquire new phenotypes that promote development and invasion of tumor cells. Understanding the underlying cellular and molecular mechanisms governing these interactions can be used as a novel strategy to indirectly disrupt cancer cell interplay and contribute to the development of efficient and safe therapeutic strategies to fight cancer. Furthermore, the tumor-derived circulating materials can also be used as cancer diagnostic tools to precisely predict and monitor the outcome of therapy. This review evaluates such potentials in various advanced cancer models, with a focus on 3D systems as well as lab-on-chip devices. Video abstract.

EphB2 represents an independent prognostic marker in patients with gastric cancer and promotes tumour cell aggressiveness

Dysregulated expression of ephrin type-B receptor 2 (EphB2) has been linked with the development and progression of solid tumours. In the current study, we attempted to investigate the clinical relevance in GC and the effect of EphB2 expression on gastric cancer (GC) cells. EphB2 protein levels in GC and benign gastric tissues were determined using immunohistochemistry. EphB2 transcript expression in a GC cohort with GC tissue samples (n=171) and paired adjacent normal gastric tissues (n=97) was determined using qPCR. The EphB2 expression was over-activated using a CRISPR activator for the investigation of its cellular function. The expression levels of the EphB2 protein in the tumour tissues of tissue arrays were higher than the benign non-cancerous gastric tissues (P<0.05). EphB2 mRNA expression in GC tissues was also significantly elevated when compared with adjacent non-cancerous tissues (P<0.01). EphB2 activation promoted the migration and invasion abilities of the GC cell lines (P<0.01, respectively). In contrast, EphB2 activation significantly decreased the adhesion in GC cells (P<0.0001, respectively). The enrichment analysis of the correlated genes in a GC cohort indicates that EphB2 may function through mediating the cytokine-cytokine interaction, JAK-STAT and TP53 signaling pathways. In conclusion, EphB2 represents as a novel independent prognostic marker in GC. And activation of the EphB2 gene expression elevated the levels of migration and invasion, but suppressed adhesion of GC cells, indicating that EphB2 may act as a tumour promotor in GC. Our findings thus provide fundamental evidence for the consideration of the therapeutic potential of targeting EphB2 in GC.

Eph/ephrin Signaling and Biology of Mesenchymal Stromal/Stem Cells

Mesenchymal stromal/stem cells (MSCs) have emerged as important therapeutic agents, owing to their easy isolation and culture, and their remarkable immunomodulatory and anti-inflammatory properties. However, MSCs constitute a heterogeneous cell population which does not express specific cell markers and has important problems for in vivo homing, and factors regulating their survival, proliferation, and differentiation are largely unknown. Accordingly, in the present article, we review the current evidence on the relationships between Eph kinase receptors, their ephrin ligands, and MSCs. These molecules are involved in the adult homeostasis of numerous tissues, and we and other authors have demonstrated their expression in human and murine MSCs derived from both bone marrow and adipose tissue, as well as their involvement in the MSC biology. We extend these studies providing new results on the effects of Eph/ephrins in the differentiation and immunomodulatory properties of MSCs.

Prognostic value of ephrin B receptors in breast cancer: An online survival analysis using the microarray data of 3,554 patients

The roles of Ephrin B (EphB) receptors in cancer are relatively unknown as these receptors are associated with complex signaling pathways. A limited number of studies have investigated the association between EphB receptors and prognosis. Using the Kaplan-Meier plotter database, the present study investigated the associations between the mRNA expression levels of five EphB receptors and the outcomes of 3,554 patients with breast cancer who had been followed-up for 20 years. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated to assess the relative risk of survival. The results demonstrated that high mRNA expression levels of EphB2 (HR, 0.74; 95% CI, 0.66-0.84; P=2.1×10-6), EphB4 (HR, 0.82; 95% CI, 0.72-0.93; P=0.0023) and EphB6 (HR, 0.69; 95% CI, 0.61-0.78; P=3×10-9) were significantly associated with improved survival, while a high mRNA expression level of EphB3 (HR, 1.14; 95% CI, 1.01-1.28; P=0.029) was associated with worse survival for patients with breast cancer. High expression levels of all EphB receptors, including EphB1 (HR, 1.4; 95% CI, 1.02-1.94; P=0.039), EphB2 (HR, 1.34; 95% CI, 1.07-1.67; P=0.011), EphB3 (HR, 1.39; 95% CI, 1.11-1.73, P=0.0038), EphB4 (HR, 1.33; 95% CI, 1.06-1.67; P=0.013) and EphB6 (HR, 1.32; 95% CI, 1.05-1.65; P=0.016), were associated with an increased risk of mortality in patients with lymph-node-positive breast cancer. High mRNA expression levels of EphB1 were not associated with survival for all patients with breast cancer (HR, 0.85; 95% CI, 0.72-1.01; P=0.058). The results of the present suggested that EphB receptors may be useful as prognostic biomarkers of breast cancer.

Viewing the Eph receptors with a focus on breast cancer heterogeneity

Aberrant expression of different family members of the Eph/ephrin system, which comprises the Eph receptors (Ephs) and their ligands (ephrins), has been implicated in various malignancies including breast cancer. The latter presents as a heterogeneous disease with diverse molecular, morphologic and clinical behavior signatures. This review reflects the existing Eph/ephrin literature while focusing on breast cancer heterogeneity. Hormone positive, HER2 positive and triple negative breast cancer (TNBC) cell lines, xenografts/mutant animal models and patient samples are examined separately as, in humans, they represent entities with differences in prognosis and treatment. EphA2, EphB4 and EphB6 are the members most extensively studied in breast cancer. Existing research points to the potential use of various Eph/ephrin members as biomarkers for assessing prognosis and selecting the most suitable therapeutic strategies in variable clinical scenarios, also for overcoming drug resistance, in the era of breast cancer heterogeneity.

Higher levels of kallikrein-8 in female brain may increase the risk for Alzheimer's disease

Women seem to have a higher vulnerability to Alzheimer's disease (AD), but the underlying mechanisms of this sex dichotomy are not well understood. Here, we first determined the influence of sex on various aspects of Alzheimer's pathology in transgenic CRND8 mice. We demonstrate that beta-amyloid (Aβ) plaque burden starts to be more severe around P180 (moderate disease stage) in female transgenics when compared to males and that aging aggravates this sex-specific difference. Furthermore, we show that female transgenics suffer from higher levels of neurovascular dysfunction around P180, resulting in impaired Aβ peptide clearance across the blood-brain-barrier at P360. Female transgenics show also higher levels of diffuse microgliosis and inflammation, but the density of microglial cells surrounding Aβ plaques is less in females. In line with this finding, testosterone compared to estradiol was able to improve microglial viability and Aβ clearance in vitro. The spatial memory of transgenics was in general poorer than in wildtypes and at P360 worse in females irrespective of their genotype. This difference was accompanied by a slightly diminished dendritic complexity in females. While all the above-named sex-differences emerged after the onset of Aβ pathology, kallikrein-8 (KLK8) protease levels were, as an exception, higher in female than in male brains very early when virtually no plaques were detectable. In a second step, we quantified cerebral KLK8 levels in AD patients and healthy controls, and could ascertain, similar to mice, higher KLK8 levels not only in AD-affected but also in healthy brains of women. Accordingly, we could demonstrate that estradiol but not testosterone induces KLK8 synthesis in neuronal and microglial cells. In conclusion, multiple features of AD are more pronounced in females. Here, we show for the first time that this sex-specific difference may be meditated by estrogen-induced KLK8 overproduction long before AD pathology emerges.

Interplay of autophagy, receptor tyrosine kinase signalling and endocytic trafficking

Vesicular trafficking events play key roles in the compartmentalization and proper sorting of cellular components. These events have crucial roles in sensing external signals, regulating protein activities and stimulating cell growth or death decisions. Although mutations in vesicle trafficking players are not direct drivers of cellular transformation, their activities are important in facilitating oncogenic pathways. One such pathway is the sensing of external stimuli and signalling through receptor tyrosine kinases (RTKs). The regulation of RTK activity by the endocytic pathway has been extensively studied. Compelling recent studies have begun to highlight the association between autophagy and RTK signalling. The influence of this interplay on cellular status and its relevance in disease settings will be discussed here.

EPH/ephrin profile and EPHB2 expression predicts patient survival in breast cancer

The EPH and ephrins function as both receptor and ligands and the output on their complex signaling is currently investigated in cancer. Previous work shows that some EPH family members have clinical value in breast cancer, suggesting that this family could be a source of novel clinical targets. Here we quantified the mRNA expression levels of EPH receptors and their ligands, ephrins, in 65 node positive breast cancer samples by RT-PCR with TaqMan^® Micro Fluidics Cards Microarray. Upon hierarchical clustering of the mRNA expression levels, we identified a subgroup of patients with high expression, and poor clinical outcome. EPHA2, EPHA4, EFNB1, EFNB2, EPHB2 and EPHB6 were significantly correlated with the cluster groups and particularly EPHB2 was an independent prognostic factor in multivariate analysis and in four public databases. The EPHB2 protein expression was also analyzed by immunohistochemistry in paraffin embedded material (cohort 2). EPHB2 was detected in the membrane and cytoplasmic cell compartments and there was an inverse correlation between membranous and cytoplasmic EPHB2. Membranous EPHB2 predicted longer breast cancer survival in both univariate and multivariate analysis while cytoplasmic EPHB2 indicated shorter breast cancer survival in univariate analysis. Concluding: the EPH/EFN cluster analysis revealed that high EPH/EFN mRNA expression is an independent prognostic factor for poor survival. Especially EPHB2 predicted poor breast cancer survival in several materials and EPHB2 protein expression has also prognostic value depending on cell localization.

Licochalcone A inhibits PI3K/Akt/mTOR signaling pathway activation and promotes autophagy in breast cancer cells

Previous studies have demonstrated that Licochalcone A possesses anti-inflammatory, anticancer, anti-bacterial, anti-malarial and anti-parasitic activities. In the present study the potential anticancer effects of Licochalcone A on MCF-7 cells were investigated. Licochalcone A significantly decreased cell viability and promoted autophagy and apoptosis, as demonstrated by an MTT assay, acridine orange staining and Annexin V-fluorescein isothiocyanate staining, respectively. Western blot analyses demonstrated that Licochalcone A treatment activated the LC3-II signaling pathway while suppressing the phosphoinositide 3-kinase (PI3K)/RAC-α serine-threonine-protein kinase (Akt)/mammalian target of rapamycin (mTOR) signaling pathway. In addition, Licochalcone A significantly increased caspase-3 activity and significantly decreased B-cell lymphoma-2 expression. The results from the present study indicate that Licochalcone A inhibits PI3K/Akt/mTOR activation, and promotes autophagy and apoptosis in MCF-7 cells.

Eps15R and clathrin regulate EphB2-mediated cell repulsion

Expression of Eph receptors and their ligands, the ephrins, have important functions in boundary formation and morphogenesis in both adult and embryonic tissue. The EphB receptors and ephrinB ligands are transmembrane proteins that are expressed in different cells and their interaction drives cell repulsion. For cell repulsion to occur, trans‐endocytosis of the inter‐cellular receptor‐ligand EphB‐ephrinB complex is required. The molecular mechanism underlying trans‐endocytosis is poorly defined. Here we show that the process is clathrin‐ and Eps15R‐mediated using Co115 colorectal cell lines stably expressing EphB2 and ephrinB1. Cell repulsion in co‐cultures of EphB2‐ and ephrinB1‐expressing cells is significantly reduced by knockdown of Eps15R but not Eps15. A novel interaction motif in Eps15R, DPFxxLDPF, is shown to bind directly to the clathrin terminal domain in vitro. Moreover, the interaction between Eps15R and clathrin is required for EphB2‐mediated cell repulsion as shown in a rescue experiment in the EphB2 co‐culture assay where wild type Eps15R but not the clathrin‐binding mutant rescues cell repulsion. These results provide the first evidence that Eps15R together with clathrin control EphB/ephrinB trans‐endocytosis and thereby cell repulsion.

The Long Noncoding RNA HOTAIR in Breast Cancer: Does Autophagy Play a Role?

HOTAIR (HOX transcript antisense RNA) plays a critical role in chromatin dynamics through the interaction with histone modifiers resulting in transcriptional gene silencing. The promoter of the HOTAIR gene contains multiple estrogen response elements (EREs) and is transcriptionally activated by estradiol in estrogen receptor-positive breast cancer cells. HOTAIR competes with BRCA1, a critical protein in breast cancer and is a critical regulator of genes involved in epithelial-to-mesenchymal transition. It mediates an oncogenic action of c-Myc, essential for breast carcinogenesis. The carcinogenic action of HOTAIR was confirmed in breast cancer stem-like cells, in which it was essential for self-renewal and proliferation. Several miRNAs regulate the expression of HOTAIR and HOTAIR interacts with many miRNAs to support cancer transformation. Many studies point at miR-34a as a major component of HOTAIR–miRNAs–cancer cross-talk. The most important role of HOTAIR can be attributed to cancer progression as its overexpression stimulates invasion and metastasis. HOTAIR can regulate autophagy, important for breast cancer cells survival, through the interaction with miRNAs specific for autophagy genes and directly with these genes. The role of HOTAIR-mediated autophagy in breast cancer progression can be underlined by its interaction with matrix metalloproteinases, essential for cancer invasion, and β-catenin can be important for this interaction. Therefore, there are several mechanisms of the interplay between HOTAIR and autophagy important for breast cancer, but further studies are needed to determine more details of this interplay.

Ubiquitin ligase SPSB4 diminishes cell repulsive responses mediated by EphB2

Eph receptor tyrosine kinases are important for cancer development and progression as well as in cellular repulsive responses. We determined that SOCS box-containing protein SPSB4 destabilizes EphB2 cytoplasmic fragments. SPSB4 is a novel ubiquitin ligase regulating EphB2-dependent cell repulsive responses.

Eph receptor tyrosine kinases and their ephrin ligands are overexpressed in various human cancers, including colorectal malignancies, suggesting important roles in many aspects of cancer development and progression as well as in cellular repulsive responses. The ectodomain of EphB2 receptor is cleaved by metalloproteinases (MMPs) MMP-2/MMP-9 and released into the extracellular space after stimulation by its ligand. The remaining membrane-associated fragment is further cleaved by the presenilin-dependent γ-secretase and releases an intracellular peptide that has tyrosine kinase activity. Although the cytoplasmic fragment is degraded by the proteasome, the responsible ubiquitin ligase has not been identified. Here, we show that SOCS box-containing protein SPSB4 polyubiquitinates EphB2 cytoplasmic fragment and that SPSB4 knockdown stabilizes the cytoplasmic fragment. Importantly, SPSB4 down-regulation enhances cell repulsive responses mediated by EphB2 stimulation. Altogether, we propose that SPSB4 is a previously unidentified ubiquitin ligase regulating EphB2-dependent cell repulsive responses.

Targeting Eph/ephrin system in cancer therapy

It is well established that the Eph/ephrin system plays a central role in the embryonic development, with minor implications in the physiology of the adult. However, it is overexpressed and deregulated in a variety of tumors, with a primary involvement in tumorigenesis, tumor angiogenesis, metastasis development, and cancer stem cell regeneration. Targeting the Eph/ephrin system with biologicals, including antibodies and recombinant proteins, reduces tumor growth in animal models of hematological malignancies, breast, prostate, colon, head and neck cancers and glioblastoma. Currently, some of these biopharmaceutical agents are under investigations in phase I or phase II clinical trials. Peptides and small molecules targeting protein-protein-interaction (PPI) are in the late preclinical phase where they are showing promising activity in models of glioblastoma, ovarian and lung cancer. The present review summarizes the most critical findings proposing the Eph/ephrin signaling system as a new target in molecularly targeted oncology.

FOXM1 expression is significantly associated with chemotherapy resistance and adverse prognosis in non-serous epithelial ovarian cancer patients

BACKGROUND

Epithelial ovarian cancer (EOC) is a spectrum of different diseases, which makes their treatment a challenge. Forkhead box M1 (FOXM1) is an oncogene aberrantly expressed in many solid cancers including serous EOC, but its role in non-serous EOCs remains undefined. We examined FOXM1 expression and its correlation to prognosis across the three major EOC subtypes, and its role in tumorigenesis and chemo-resistance in vitro.

METHODS

Gene signatures were generated by microarray for 14 clear-cell and 26 endometrioid EOCs, and 15 normal endometrium snap-frozen biopsies. Validation of FOXM1 expression was performed by RT-qPCR and immunohistochemistry in the same samples and additionally in 50 high-grade serous EOCs and in their most adequate normal controls (10 luminal fallopian tube and 20 ovarian surface epithelial brushings). Correlations of FOXM1 expression to clinic-pathological parameters and patients' prognosis were evaluated by Kaplan-Meier and Cox proportional-hazards analyses. OVCAR-3 and two novel deeply characterized EOC cell lines (EOC-CC1 and OSPC2, with clear-cell and serous subtype, respectively) were employed for in vitro studies. Effects of FOXM1 inhibition by transient siRNA transfection were evaluated on cell-proliferation, cell-cycle, colony formation, invasion, and response to conventional first- and second-line anticancer agents, and to the PARP-inhibitor olaparib. Gene signatures of FOXM1-silenced cell lines were generated by microarray and confirmed by RT-qPCR.

RESULTS

A significant FOXM1 mRNA up-regulation was found in EOCs compared to normal controls. FOXM1 protein overexpression significantly correlated to serous histology (p = 0.001) and advanced FIGO stage (p = 0.004). Multivariate analyses confirmed FOXM1 protein overexpression as an independent indicator of worse disease specific survival in non-serous EOCs, and of shorter time to progression in platinum-resistant cases. FOXM1 downregulation in EOC cell lines inhibited cell growth and clonogenicity, and promoted the cytotoxic effects of platinum compounds, doxorubicin hydrochloride and olaparib. Upon FOXM1 knock-down in EOC-CC1 and OSPC2 cells, microarray and RT-qPCR analyses revealed the deregulation of several common and other unique subtype-specific FOXM1 putative targets involved in cell cycle, metastasis, DNA repair and drug response.

CONCLUSIONS

FOXM1 is up-regulated in all three major EOCs subtypes, and is a prognostic biomarker and a potential combinatorial therapeutic target in platinum resistant disease, irrespective of tumor histology.

Kallikrein-8 inhibition attenuates Alzheimer's disease pathology in mice

INTRODUCTION

Memory loss and increased anxiety are clinical hallmarks of Alzheimer's disease (AD). Kallikrein-8 is a protease implicated in memory acquisition and anxiety, and its mRNA is known to be up-regulated in AD-affected human hippocampus. Therefore, an involvement of Kallikrein-8 in Alzheimer's pathogenesis is conceivable but remains to be proved.

METHODS

We determined the cerebral expression of Kallikrein-8 mRNA and protein during the course of AD in patients and in transgenic mice and tested the impact of Kallikrein-8 inhibition on AD-related pathology in mice and in primary glial cells.

RESULTS

Kallikrein-8 mRNA and protein were up-regulated in both species at incipient stages of AD. Kallikrein-8 inhibition impeded amyloidogenic amyloid-precursor-protein processing, facilitated amyloid β (Aβ) clearance across the blood-brain-barrier, boosted autophagy, reduced Aβ load and tau pathology, enhanced neuroplasticity, reversed molecular signatures of anxiety, and ultimately improved memory and reduced fear.

DISCUSSION

Kallikrein-8 is a promising new therapeutic target against AD.

Alzheimer's disease genes and autophagy

Autophagy is a process to degrade and recycle cellular constituents via the lysosome for regulating cellular homeostasis. Its dysfunction is now considered to be involved in many diseases, including neurodegenerative diseases. Many features reflecting autophagy impairment, such as autophagosome accumulation and lysosomal dysfunction, have been also revealed to be involved in Alzheimer's disease (AD). Recent genetic studies such as genome-wide association studies in AD have identified a number of novel genes associated with AD. Some of the identified genes have demonstrated dysfunction in autophagic processes in AD, while others remain under investigation. Since autophagy is strongly regarded to be one of the major pathogenic mechanisms of AD, it is necessary to review how the AD-associated genes are related to autophagy. We anticipate our current review to be a starting point for future studies regarding AD-associated genes and autophagy. This article is part of a Special Issue entitled SI:Autophagy.

The role of proteases in regulating Eph/ephrin signaling

Proteases regulate a myriad of cell functions, both in normal and disease states. In addition to protein turnover, they regulate a range of signaling processes, including those mediated by Eph receptors and their ephrin ligands. A variety of proteases is reported to directly cleave Ephs and/or ephrins under different conditions, to promote receptor and/or ligand shedding, and regulate receptor/ligand internalisation and signaling. They also cleave other adhesion proteins in response to Eph-ephrin interactions, to indirectly facilitate Eph-mediated functions. Proteases thus contribute to Eph/ephrin mediated changes in cell-cell and cell-matrix interactions, in cell morphology and in cell migration and invasion, in a manner which appears to be tightly regulated by, and co-ordinated with, Eph signaling. This review summarizes the current literature describing the function and regulation of protease activities during Eph/ephrin-mediated cell signaling.

Eph family co-expression patterns define unique clusters predictive of cancer phenotype

The Eph genes are the largest sub-family of receptor tyrosine kinases; however, it is most likely the least understood and the arena for many conflicting reports. In this tribute to Prof. Martin Lackmann and Prof. Tony Pawson, we utilized The Cancer Genome Atlas resources to shed new light on the understanding of this family. We found that mutation and expression analysis define two clusters of co-expressed Eph family genes that relate to aggressive phenotypes across multiple cancer types. Analysis of signal transduction pathways using reverse-phase protein arrays revealed a network of interactions, which associates cluster-specific Eph genes with epithelial-mesenchymal transition, metabolism, DNA-damage repair and apoptosis. Our findings support the role of the Eph family in modulating cancer progression and reveal distinct patterns of Eph expression, which correlate with disease outcome. These observations provide further rationale for seeking cancer therapies, which target the Eph/ephrin system.