Phosphorylated 4E binding protein 1: a hallmark of cell signaling that correlates with survival in ovarian cancer

Regulation of Eukaryotic Translation Initiation Factor 4E as a Potential Anticancer Strategy

Eukaryotic translation initiation factors (eIFs) are highly expressed in cancer cells, especially eIF4E, the central regulatory node driving cancer cell growth and a potential target for anticancer drugs. eIF4E-targeting strategies primarily focus on inhibiting eIF4E synthesis, interfering with eIF4E/eIF4G interactions, and targeting eIF4E phosphorylation and peptide inhibitors. Although some small-molecule inhibitors are in clinical trials, no eIF4E inhibitors are available for clinical use. We provide an overview of the regulatory mechanisms of eIF4E and summarize the progress in developing and discovering eIF4E inhibitor strategies. We propose that interference with eIF4E/eIF4G interactions will provide a new perspective for the design of eIF4E inhibitors and may be a preferred strategy.

The multifaced role and therapeutic regulation of autophagy in ovarian cancer

Ovarian cancer (OC) is one of the tumors that occurs most frequently in women. Autophagy is involved in cell homeostasis, biomolecule recycling, and survival, making it a potential target for anti-tumor drugs. It is worth noting that growing evidence reveals a close link between autophagy and OC. In the context of OC, autophagy demonstrates activity as both a tumor suppressor and a tumor promoter, depending on the context. Autophagy's exact function in OC is greatly reliant on the tumor microenvironment (TME) and other conditions, such as hypoxia, nutritional deficiency, chemotherapy, and so on. However, what can be concluded from different studies is that autophagy-related signaling pathways, especially PI3K/AKT/mTOR axis, increase in advanced stages and malignant phenotype of the disease reduces autophagy and ultimately leads to tumor progression. This study sought to present a thorough understanding of the role of autophagy-related signaling pathways in OC and existing therapies targeting these signaling pathways.

Vemurafenib inhibits immune escape biomarker BCL2A1 by targeting PI3K/AKT signaling pathway to suppress breast cancer

Objectives

To investigate the role of immune escape encoding genes on the prognosis of BC, and to predict the novel targeting agents.

Methods

Human immune genes and immune escape encoding genes were obtained from the IMMPORT database and the previous study. Sample information and clinical data on BC were obtained from the TCGA and GTEX databases. Obtaining differentially expressed protein data from cBioportal database. To construct a risk score model by lasso analysis, and nomogram was used to predict score core. GSCA, TIMER and CELLMINER databases were used for immune and drug susceptibility correlation analyses. Cell experiments were verified by MTT, Western blotting, and RT-qPCR.

Results

We found prognostic models consisting of eleven immune escape related protein-coding genes with ROC curves that performed well in the ontology data (AUC for TCGA is 0.672) and the external data (AUC for GSE20685 is 0.663 and for GES42568 is 0.706). Five core prognostic models are related to survival (EIF4EBP1, BCL2A1, NDRG1, ERRFI1 and BRD4) were summarized, and a nomogram was constructed to validate a C-index of 0.695, which was superior to other prognostic models. Relevant drugs targeting core genes were identified based on drug sensitivity analysis, and found that Vemurafenib downregulates the PI3K-AKT pathway and BCL2A1 protein in BC, as confirmed by external data and cellular assays.

Conclusions

Briefly, our work establishes and validates an 11-immune escape risk model, and five core prognostic factors that are mined deeply from this model, and elucidates in detail that Vemurafenib suppresses breast cancer by targeting the PI3K/AKT signaling pathway to inhibit the immune escape biomarker BCL2A1, confirms the validity of the prognostic model, and provides corresponding targeted agents to guide individualized treatment of BC patients.

Aberrant protein synthesis and cancer development: The role of canonical eukaryotic initiation, elongation and termination factors in tumorigenesis

In tumourigenesis, oncogenes or dysregulated tumour suppressor genes alter the canonical translation machinery leading to a reprogramming of the translatome that, in turn, promotes the translation of selected mRNAs encoding proteins involved in proliferation and metastasis. It is therefore unsurprising that abnormal expression levels and activities of eukaryotic initiation factors (eIFs), elongation factors (eEFs) or termination factors (eRFs) are associated with poor outcome for patients with a wide range of cancers. In this review we discuss how RNA binding proteins (RBPs) within the canonical translation factor machinery are dysregulated in cancers and how targeting such proteins is leading to new therapeutic avenues.

Translation initiation and its relationship with metabolic mechanisms in cancer development, progression and chemoresistance

Pathways that regulate protein homeostasis (proteostasis) in cells range from mRNA processing to protein degradation; perturbations in regulatory mechanisms of these pathways can lead to oncogenic cellular processes. Protein synthesis modulation failures are common phenomena in cancer cells, wherein specific conditions that promote the translation of protein factors promoting carcinogenesis are present. These specific conditions may be favored by metabolic lipid alterations like those found in metabolic syndrome and obesity. Protein translation modifications have been described in obesity, favoring the translation of protein targets that benefit lipid accumulation; a determining factor is the activity of the cap-binding eukaryotic translation initiation factor 4E (eIF4E), a crosstalk in protein translation and lipogenesis. Besides, alterations of protein translation initiation steps are critical participants for the development of both pathogenic conditions, cancer, and obesity. This chapter is focused on the regulation of recognition and processing of carcinogenic-mRNA and the connections among lipid metabolism and cell signaling pathways that promote oncogenesis, tumoral microenvironment generation and potentially the development of chemoresistance. We performed an in-depth analysis of events, such as those occurring in obesity and dyslipidemias, that may influence protein translation, driving the recognition of certain mRNAs and favoring cancer development and chemoresistance.

Mechanisms of miR-3189-3p-mediated inhibition of c-MYC translation in triple negative breast cancer

BACKGROUND

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by the lack of estrogen receptor, progesterone receptor, and HER2. Our lab previously characterized miR-3189-3p as a microRNA with potent anti-cancer activity against glioblastoma. Here, we hypothesized a similar activity in TNBC cells. As miR-3189-3p is predicted to target a variety of RNA binding proteins, we further hypothesized an inhibitory effect of this miRNA on protein synthesis.

METHODS

MDA-MB-231 and MDA-MB-468 cells were used to investigate the effect of miR-3189-3p on cell proliferation, migration, and invasion. TGCA database was used to analyze the expression of miR-3189-3p, c-MYC, 4EPB1, and eIF4E in breast cancer. Western blotting and RT-qPCR assays were used to assess the expression of selected proteins and RNAs after transfections.

RESULTS

Although c-MYC is not a predicted gene target for miR-3189-3p, we discovered that c-MYC protein is downregulated in miRNA-treated TNBC cells. We found that the downregulation of c-MYC by miR-3189-3p occurs in both normal growth conditions and in the absence of serum. The mechanism involved the direct inhibition of eIF4EBP1 by miR-3189-3p. Additionally, we found that miR-3189-3p could negatively affect cap-independent translation mediated by internal ribosome entry sites (IRES) or by m6A. Finally, miR-3189-3p sensitized TNBC cells to doxorubicin.

CONCLUSION

Overall, results indicated that miR-3189-3p exerts its anti-tumor activity through targeting translational regulatory proteins leading to an impairment in c-MYC translation, and possibly other oncogenic factors, suggesting that miR-3189-3p, alone or in combination, could be a valuable therapeutic approach against a malignancy with few treatment options.

Targeting the PI3K/AKT/mTOR pathway in epithelial ovarian cancer, therapeutic treatment options for platinum-resistant ovarian cancer

The survival rates for women with ovarian cancer have shown scant improvement in recent years, with a 5-year survival rate of less than 40% for women diagnosed with advanced ovarian cancer. High-grade serous ovarian cancer (HGSOC) is the most lethal subtype where the majority of women develop recurrent disease and chemotherapy resistance, despite over 70%-80% of patients initially responding to platinum-based chemotherapy. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway regulates many vital processes such as cell growth, survival and metabolism. However, this pathway is frequently dysregulated in cancers including different subtypes of ovarian cancer, through amplification or somatic mutations of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), amplification of AKT isoforms, or deletion or inactivation of PTEN. Further evidence indicates a role for the PI3K/AKT/mTOR pathway in the development of chemotherapy resistance in ovarian cancer. Thus, targeting key nodes of the PI3K/AKT/mTOR pathway is a potential therapeutic prospect. In this review, we outline dysregulation of PI3K signaling in ovarian cancer, with a particular emphasis on HGSOC and platinum-resistant disease. We review pre-clinical evidence for inhibitors of the main components of the PI3K pathway and highlight past, current and upcoming trials in ovarian cancers for different inhibitors of the pathway. Whilst no inhibitors of the PI3K/AKT/mTOR pathway have thus far advanced to the clinic for the treatment of ovarian cancer, several promising compounds which have the potential to restore platinum sensitivity and improve clinical outcomes for patients are under evaluation and in various phases of clinical trials.

An Overview of Promising Biomarkers in Cancer Screening and Detection

Applications of biomarkers have been proved in oncology screening, diagnosis, predicting response to treatment as well as monitoring the progress of the disease. Considering the crucial role played by them during different disease stages, it is extremely important to evaluate, validate, and assess them to incorporate them into routine clinical care. In this review, the role of few most promising and successfully used biomarkers in cancer detection, i.e. PD-L1, E-Cadherin, TP53, Exosomes, cfDNA, EGFR, mTOR with regard to their structure, mode of action, and reports signifying their pathological significance, are addressed. Also, an overview of some successfully used biomarkers for cancer medicine has been presented. The study also summarizes biomarker-driven personalized cancer therapy i.e., approved targets and indications, as per the US FDA. The review also highlights the increasingly prominent role of biomarkers in drug development at all stages, with particular reference to clinical trials. The increasing utility of biomarkers in clinical trials is clearly evident from the trend shown, wherein ~55 percent of all oncology clinical trials in 2019 were seen to involve biomarkers, as opposed to ~ 15 percent in 2001, which clearly proves the essence and applicability of biomarkers for synergizing clinical information with tumor progression. Still, there are significant challenges in the implementation of these possibilities with strong evidence in cost-- effective manner.

Targeting the PI3K pathway and DNA damage response as a therapeutic strategy in ovarian cancer

Ovarian cancer is the most lethal gynecological malignancy worldwide although exponential progress has been made in its treatment over the last decade. New agents and novel combination treatments are on the horizon. Among many new drugs, a series of PI3K/AKT/mTOR pathway (referred to as the PI3K pathway) inhibitors are under development or already in clinical testing. The PI3K pathway is frequently upregulated in ovarian cancer and activated PI3K signaling contributes to increased cell survival and chemoresistance. However, no significant clinical success has been achieved with the PI3K pathway inhibitor(s) to date, reflecting the complex biology and also highlighting the need for combination treatment strategies. DNA damage repair pathways have been active therapeutic targets in ovarian cancer. Emerging data suggest the PI3K pathway is also involved in DNA replication and genome stability, making DNA damage response (DDR) inhibitors as an attractive combination treatment for PI3K pathway blockades. This review describes an expanded role for the PI3K pathway in the context of DDR and cell cycle regulation. We also present the novel treatment strategies combining PI3K pathway inhibitors with DDR blockades to improve the efficacy of these inhibitors for ovarian cancer.

Clinical implications of intratumor heterogeneity: challenges and opportunities

In this review, we highlight the role of intratumoral heterogeneity, focusing on the clinical and biological ramifications this phenomenon poses. Intratumoral heterogeneity arises through complex genetic, epigenetic, and protein modifications that drive phenotypic selection in response to environmental pressures. Functionally, heterogeneity provides tumors with significant adaptability. This ranges from mutual beneficial cooperation between cells, which nurture features such as growth and metastasis, to the narrow escape and survival of clonal cell populations that have adapted to thrive under specific conditions such as hypoxia or chemotherapy. These dynamic intercellular interplays are guided by a Darwinian selection landscape between clonal tumor cell populations and the tumor microenvironment. Understanding the involved drivers and functional consequences of such tumor heterogeneity is challenging but also promises to provide novel insight needed to confront the problem of therapeutic resistance in tumors.

Targeting the PI3K/AKT/mTOR/NFκB Axis in Ovarian Cancer

Ovarian cancer stands as the most lethal gynecologic malignancy and remains the fifth most common gynecologic cancer. Poor prognosis and low five-year survival rate are attributed to nonspecific symptoms at early phases along with a lack of effective treatment at advanced stages. It is thus paramount, that ovarian carcinoma be viewed through several lenses in order to gain a thorough comprehension of its molecular pathogenesis, epidemiology, histological subtypes, hereditary factors, diagnostic approaches, and methods of treatment. Above all, it is crucial to dissect the role that the unique peritoneal tumor microenvironment plays in ovarian cancer progression and metastasis. This short communication seeks to underscore several important aspects of the PI3K/AKT/mTOR/NFκB pathway in the context of ovarian cancer and discuss recent advances in targeting this pathway.

MTHFD1L-Mediated Redox Homeostasis Promotes Tumor Progression in Tongue Squamous Cell Carcinoma

Background: Routine changes in cell metabolism can drive tumor development, as the cellular program develops to promote glycolysis and redox homeostasis during tumor progression; however, the associated mechanisms in tongue squamous cell carcinoma (TSCC) remain unclear.

Methods: We investigated methylenetetrahydrofolate dehydrogenase 1-like (MTHFD1L) expression, its clinical relevance, redox modification, and molecular mechanisms using TSCC cells and tissues. The anti-tumor effects of MTHFD1L knockdown on TSCC tumorigenesis were evaluated in vitro and in vivo. Kaplan-Meier curves and the log-rank test were used to analyze disease-free survival and overall survival.

Results: TSCC patients with high expression levels of MTHFD1L had shorter overall survival (P < 0.05) and disease-free survival (P < 0.05). Knockdown of MTHFD1L reduced nicotinamide adenine dinucleotide phosphate (NADPH) levels and increased reactive oxygen species (ROS), which accelerated cell death under oxidative stress, such as hypoxia or glucose deprivation. Additionally, inhibition of MTHFD1L suppressed TSCC cell growth and delayed the cell cycle, including in xenograft experiments.

Conclusions: MTHFD1L confers redox homeostasis and promotes TSCC cell growth, which provides a great opportunity to study tumor metabolism in head and neck cancer. The mTORC1-4EBP1-eIF4E axis may affect the expression of MTHFD1L in TSCC. Inhibition of the expression of MTHFD1L may be an actionable and effective therapeutic target in TSCC.

PI3K-AKT-mTOR and NFκB Pathways in Ovarian Cancer: Implications for Targeted Therapeutics

Ovarian cancer is the most lethal gynecologic malignancy in the United States, with an estimated 22,530 new cases and 13,980 deaths in 2019. Recent studies have indicated that the phosphoinositol 3 kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR), as well as the nuclear factor-κ light chain enhancer of activated B cells (NFκB) pathways are highly mutated and/or hyper-activated in a majority of ovarian cancer patients, and are associated with advanced grade and stage disease and poor prognosis. In this review, we will investigate PI3K/AKT/mTOR and their interconnection with NFκB pathway in ovarian cancer cells.

Simultaneous activation of impaired autophagy and the mammalian target of rapamycin pathway in oral squamous cell carcinoma

BACKGROUND

The aim of this study was to conduct a comparative evaluation of the expression levels of autophagy markers and proteins of the mammalian target of rapamycin (mTOR) pathway in normal, margin and tumour tissues of patients with oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Three regional specimens, including normal, margin and tumour tissues, were collected from 26 patients with OSCC. Western blotting, immunohistochemistry and immunofluorescence staining were performed to detect mTOR, eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), p70 ribosomal S6 protein kinase (p70S6K) and the corresponding phosphorylated proteins, as well as the light chain 3 (LC3) and sequestosome-1 (SQSTM1, also known as p62) autophagy indicators.

RESULTS

LC3-II, p62, mTOR, phospho-mTOR, 4E-BP1 and phospho-4E-BP1 were highly expressed in the margin and tumour groups. There were positive correlations between mTOR/phospho-mTOR, mTOR/4E-BP1, mTOR/phospho-4E-BP1, mTOR/p70S6K, LC3-II/p62, LC3-II/p70S6K, p62/4E-BP1 and p62/phospho-4E-BP1 in normal group, while LC3-II/p62, LC3-II/mTOR, LC3-II/4E-BP1, LC3-II/phospho-4E-BP1, phospho-4E-BP1/mTOR, phospho-4E-BP1/4E-BP1 and p62/4E-BP1 showed positive relationships in margin group; however, in tumour group, only mTOR/phospho-mTOR, 4E-BP1/phospho-4E-BP1 and phospho-mTOR/p70S6K showed positive correlations.

CONCLUSION

The study suggests that autophagy is impaired in patients with OSCC and impaired autophagy and the mTOR pathway are simultaneously activated in OSCC cells.

Chemoproteomic Profiling Uncovers CDK4-Mediated Phosphorylation of the Translational Suppressor 4E-BP1

Recent estimates of the human proteome suggest there are ∼20,000 protein-coding genes, the protein products of which contain >145,000 phosphosites. Unfortunately, in-depth examination of the human phosphoproteome has outpaced the ability to annotate the kinases that mediate these post-translational modifications. To obtain actionable information about phosphorylation-driven signaling cascades, it is essential to identify the kinases responsible for phosphorylating sites that differ across disease states. To fill in these gaps we have developed an unbiased, chemoproteomic approach for identifying high-confidence kinase-substrate interactions with phosphosite specificity. Using this assay, we uncovered the role of cyclin-dependent kinase 4 (CDK4), a clinically validated kinase important for cell-cycle progression, in regulating cap-dependent translation via phosphorylation of the tumor suppressor 4E-BP1. The discovery of this signaling axis sheds light on the mechanisms by which CDK4/6 inhibitors control cell proliferation and constitutes a successful example of kinase discovery using an activity-based, kinase-directed probe.

Targeting eIF4E signaling with ribavirin as a sensitizing strategy for ovarian cancer

The essential roles of eukaryotic translation initiation factor 4E (eIF4E) have been shown in various cancers, including ovarian cancer. In this work, we demonstrate that eIF4E inhibition in ovarian cancer can be achieved by ribavirin, a FDA-approved antiviral drug. We show that ribavirin at clinically relevant doses significantly inhibits growth and survival in multiple ovarian cancer cell lines, regardless of morphological and molecular subtypes. Mechanistically, ribavirin suppresses Akt/mTOR and eIF4E/p70S6K signaling pathways in ovarian cancer cells. We confirm that eIF4E is the critical molecular target of ribavirin, and furthermore that this is dependent on phosphorylation at S209. Notably, using both in vitro cell culture system and in vivo xenograft mouse model, we show that the combination of ribavirin with cisplatin (standard of care for patients with ovarian cancer) results in significantly greater efficacy than cisplatin alone in ovarian cancer. Interestingly, the sensitivity to ribavirin varies among a panel of ovarian cancer cell lines, mostly likely due to their differential expression level of eIF4E and dependency to eIF4E inhibition. The differential expression level is further observed in ovarian cancer tissues, with the higher level of eIF4E in the majority of ovarian cancer tissues compared to normal ovary tissues. Our work suggests that eIF4E expression varies among ovarian cancer. Additionally, ribavirin is a useful addition to ovarian cancer treatment, particularly to those with high dependency on eIF4E.

The mTOR downstream regulator (p-4EBP1) is a novel independent prognostic marker in ovarian cancer

Ovarian cancer is associated with the highest mortality rate among gynaecologic malignancies. There is a need to refine the classification of ovarian cancer and identify novel targets. The mammalian target of rapamycin (mTOR) pathway has a crucial role in the pathogenesis and progression of ovarian cancer. This study aims to investigate the prognostic role of p-mTOR and its major downstream effectors p-4EBP1 (eukaryotic initiation factor 4E-binding protein 1) and p-P70S6K (ribosomal protein S6 kinase) in ovarian cancer. p-mTOR, p-4EBP1 and p-P70S6K protein expression was assessed on 195 consecutive ovarian epithelial cancers and correlated to clinicopathological features and survival. We found that high cytoplasmic expression of p-4EBP1 and p-P70S6K was associated with a serous type carcinoma (p = .005) and an advanced FIGO stage (p = .012), respectively. Univariate outcome analysis showed an inverse association between a high expression of p-4EBP1 expression and overall ovarian cancer survival (OS; p = .005) and progression-free survival (PFS; p = .005). p-P70S6K showed an inverse association with PFS (p = .001). Multivariate analyses indicated that p-4EBP1 was an independent predictor of both OS and PFS (p = .016 and p = .041, respectively). Therefore, we concluded that p-4EBP1 high protein expression is an independent predictor of outcome in ovarian cancer patients. Therefore, it could be used as a potential biomarker for prognostic stratification and treatment decisions. Impact statement What is already known on this subject? The mammalian target of rapamycin (mTOR) pathway has a crucial role in the pathogenesis and progression of ovarian cancer. To-date, very limited knowledge is known about the importance of mTOR major downstream effectors p-4EBP1 (eukaryotic initiation factor 4E-binding protein 1) and p-P70S6K (ribosomal protein S6 kinase) in ovarian cancer. What do the results of this study add? In this study, we have provided further evidence of the adverse prognostic behaviour associated with the positive expression of p-mTOR and its major downstream effectors. Moreover and by performing multivariate analysis, we for the first time have proved that p-4EBP1 is an independent predictor of clinical outcome in ovarian cancer. What are the implications of these findings for clinical practice and/or further research? p-4EBP1 could be used as a potential biomarker for prognostic stratification and treatment decisions in ovarian cancer management.

Inhibition of mTORC1 by lncRNA H19 via disrupting 4E-BP1/Raptor interaction in pituitary tumours

Aberrant expression of long noncoding RNA H19 has been associated with tumour progression, but the underlying molecular tumourigenesis mechanisms remain largely unknown. Here, we report that H19 expression is frequently downregulated in human primary pituitary adenomas and is negatively correlated with tumour progression. Consistently, upregulation of H19 expression inhibits pituitary tumour cell proliferation in vitro and tumour growth in vivo. Importantly, we uncover a function of H19, which controls cell/tumour growth through inhibiting function of mTORC1 but not mTORC2. Mechanistically, we show that H19 could block mTORC1-mediated 4E-BP1 phosphorylation without affecting S6K1 activation. At the molecular level, H19 interacted with 4E-BP1 at the TOS motif and competitively inhibited 4E-BP1 binding to Raptor. Finally, we demonstrate that H19 is more effective than cabergoline treatment in the suppression of pituitary tumours. Together, our study uncovered the role of H19-mTOR-4E-BP1 axis in pituitary tumour growth regulation that may be a potential therapeutic target for human pituitary tumours.

LncRNA H19 has been shown to be aberrantly expressed in different cancers. Here, the authors show that H19 lncRNA is downregulated in pituitary adenomas and H19 is able to impede pituitary tumorigenesis via disruption of 4E-BPB1 and Raptor interaction to inhibit the phosphorylation of 4E-BP1.

Beyond molecular tumor heterogeneity: protein synthesis takes control

One of the daunting challenges facing modern medicine lies in the understanding and treatment of tumor heterogeneity. Most tumors show intra-tumor heterogeneity at both genomic and proteomic levels, with marked impacts on the responses of therapeutic targets. Therapeutic target-related gene expression pathways are affected by hypoxia and cellular stress. However, the finding that targets such as eukaryotic initiation factor (eIF) 4E (and its phosphorylated form, p-eIF4E) are generally homogenously expressed throughout tumors, regardless of the presence of hypoxia or other cellular stress conditions, opens the exciting possibility that malignancies could be treated with therapies that combine targeting of eIF4E phosphorylation with immune checkpoint inhibitors or chemotherapy.

The prognostic value of HER2 in ovarian cancer: A meta-analysis of observational studies

BACKGROUND

The prognostic role of human epidermal growth factor receptor 2 (HER2) in ovarian cancer has been investigated in previous studies, but the results remain controversial. Here we present a meta-analysis to systematically review the association between HER2 expression and ovarian cancer prognosis.

METHOD

Observational studies published until July 2017 were searched in Pubmed, Embase, and Cochrane library databases. Hazard ratios (HRs) for survival with 95% confidence intervals (CIs), subgroup analyses, publication bias and sensitivity analyses were implemented under a standard manner. Estimates of overall survival (OS), progress-free survival (PFS) and disease-free survival (DFS) were weighted and pooled using Der Simonian-Laird random-effect model.

RESULT

Thirty-four studies that include 5180 ovarian cancer patients were collected for analysis. Expression of HER2 was negatively correlated with clinical prognosis of overall survival (HR = 1.57, 95% CI: 1.31 to 1.89, P < 0.001) and disease-free survival / progress-free survival (HR = 1.26, 95% CI = 1.06 to 1.49) in ovarian cancers. The association between HER2 expression and poor ovarian cancer prognosis in overall survival was also statistically significant in subgroups of unclassified ovarian cancer, Caucasian population and Asian population, while irrespective of detection method.

CONCLUSION

HER2 expression was related with poor prognosis in ovarian cancer patients and can be used as a predicting cancer prognostic biomarker in ovarian cancer patients.

Meta-analysis of the prognostic value of p-4EBP1 in human malignancies

Phosphorylated 4E-binding protein 1 (p-4EBP1) is the inactivated form of 4EBP1, which is a downstream mediator in the mTOR signaling pathway and a vital factor in the synthesis of some oncogenic proteins. This meta-analysis was conducted to assess the predicative value of p-4EBP1 expression in human malignancies. The PubMed and Embase databases were carefully searched. Articles comparing the prognostic worthiness of different p-4EBP1 levels in human malignancies were collected for pooled analyses and methodologically appraised using the Newcastle-Ottawa Scale (NOS). A total of 39 retrospective cohorts with an overall sample size of 3,980 were selected. Patients with lower p-4EBP1 expression had better 3-year (P < 0.00001), 5-year (P < 0.00001), and 10-year (P = 0.03) overall survival and better 3-year (P < 0.0001) and 5-year (P = 0.0005) disease-free survival. Subgroup analyses confirmed the unfavorable prognosis associated with p-4EBP1 overexpression. These findings were further validated by sensitivity analyses. Harbord and Peters tests revealed no publication bias within the included studies. It thus appears higher expression of p-4EBP1 indicates a poor prognosis in human malignancies.

Eukaryotic initiation factor 4F-sidestepping resistance mechanisms arising from expression heterogeneity

There is enormous diversity in the genetic makeup and gene expression profiles between and within tumors. This heterogeneity leads to phenotypic variation and is a major mechanism of resistance to molecular targeted therapies. Here we describe a conceptual framework for targeting eukaryotic initiation factor (eIF) 4F in cancer-an essential complex that drives and promotes multiple Cancer Hallmarks. The unique nature of eIF4F and its druggability bypasses several of the heterogeneity issues that plague molecular targeted drugs developed for cancer therapy.

Cancer as an ecomolecular disease and a neoplastic consortium

Current anticancer paradigms largely target driver mutations considered integral for cancer cell survival and tumor progression. Although initially successful, many of these strategies are unable to overcome the tremendous heterogeneity that characterizes advanced tumors, resulting in the emergence of resistant disease. Cancer is a rapidly evolving, multifactorial disease that accumulates numerous genetic and epigenetic alterations. This results in wide phenotypic and molecular heterogeneity within the tumor, the complexity of which is further amplified through specific interactions between cancer cells and the tumor microenvironment. In this context, cancer may be perceived as an "ecomolecular" disease that involves cooperation between several neoplastic clones and their interactions with immune cells, stromal fibroblasts, and other cell types present in the microenvironment. This collaboration is mediated by a variety of secreted factors. Cancer is therefore analogous to complex ecosystems such as microbial consortia. In the present article, we comment on the current paradigms and perspectives guiding the development of cancer diagnostics and therapeutics and the potential application of systems biology to untangle the complexity of neoplasia. In our opinion, conceptualization of neoplasia as an ecomolecular disease is warranted. Advances in knowledge pertinent to the complexity and dynamics of interactions within the cancer ecosystem are likely to improve understanding of tumor etiology, pathogenesis, and progression. This knowledge is anticipated to facilitate the design of new and more effective therapeutic approaches that target the tumor ecosystem in its entirety.

Prognostic value of HER-2/neu expression in epithelial ovarian cancer: a systematic review and meta-analysis

This study aimed to conduct a meta-analysis to investigate the association between human epidermal growth factor receptor 2 (HER-2/neu) expression and survival in patients with epithelial ovarian cancer (EOC). HER-2/neu is one of the most frequently studied molecular biological parameters in EOC, but its prognostic impact has not been fully assessed. PubMed and Embase were searched for studies that reported HER-2/neu expression and survival in patients with EOC. The primary outcome was overall survival (OS), and the secondary outcome was progression-free survival (PFS). Hazard ratios (HRs) with 95% confidence interval (CI) were determined using Mantel-Haenszel random-effects model. Publication bias was investigated using funnel plots and Egger's test. A total of 56 studies (N=7212) were included in the analysis. The results showed that patients possessing HER-2/neu expression had significant disadvantages in OS (HR = 1.41; 95%CI, 1.31 to 1.51; P < 0.001) and PFS (HR = 1.38; 95% CI, 1.23-1.56; P < 0.001). The trim-and-fill method, Copas model, and subgroup analyses stratified by the study characteristics confirmed the robustness of the results. The present study findings provided further indication that HER-2/neu expression in patients with EOC has an adverse impact on OS and PFS.

Eukaryotic translation initiation factors and cancer

Recent technological advancements have shown tremendous mechanistic accomplishments in our understanding of the mechanism of messenger RNA translation in eukaryotic cells. Eukaryotic messenger RNA translation is very complex process that includes four phases (initiation, elongation, termination, and ribosome recycling) and diverse mechanisms involving protein and non-protein molecules. Translation regulation is principally achieved during initiation step of translation, which is organized by multiple eukaryotic translation initiation factors. Eukaryotic translation initiation factor proteins help in stabilizing the formation of the functional ribosome around the start codon and provide regulatory mechanisms in translation initiation. Dysregulated messenger RNA translation is a common feature of tumorigenesis. Various oncogenic and tumor suppressive genes affect/are affected by the translation machinery, making the components of the translation apparatus promising therapeutic targets for the novel anticancer drug. This review provides details on the role of eukaryotic translation initiation factors in messenger RNA translation initiation, their contribution to onset and progression of tumor, and how dysregulated eukaryotic translation initiation factors can be used as a target to treat carcinogenesis.

EGFR as a prognostic biomarker and therapeutic target in ovarian cancer: evaluation of patient cohort and literature review

Background

Limited effectiveness of therapeutic agents targeting epidermal growth factor receptor (EGFR) in clinical trials using unselected ovarian cancer patients has prompted efforts to more effectively stratify patients who might best benefit from these therapies. A series of studies that have evaluated immunohistochemical (IHC) staining of EGFR in ovarian cancer biopsies has produced unclear results as to the utility of this measure as a prognostic biomarker. Here, we used one of the largest, single institution cohorts to date to determine possible associations of EGFR expression with patient outcome.

Methods

We performed IHC staining of EGFR in tissue microarrays including nearly 500 patient tumor samples. Staining was classified by subcellular localization (membranous, cytoplasmic) or by automated image analysis algorithms. We also performed a literature review to place these results in the context of previous studies.

Results

No significant associations were found between EGFR subcellular localization or expression and histology, stage, grade, or outcome. These results were broadly consistent with the consensus of the reviewed literature.

Conclusions

These results suggest that IHC staining for EGFR may not be a useful prognostic biomarker for ovarian cancer patients. Future studies should pursue other staining methods or analysis in combination with other pathway mediators.

Increased phosphorylation of 4E‑binding protein 1 predicts poor prognosis for patients with colorectal cancer

As demonstrated in previous studies, the phosphorylated form of 4E‑binding protein 1 (p‑4E‑BP1) may be a suitable tumor biomarker. The aim of the current study was to examine the expression status of p‑4E‑BP1 in colorectal cancer (CRC), in order to determine its clinical significance. The present study enrolled 89 patients with CRC that had undergone radical resection. Paired tumor and adjacent normal tissues were evaluated using immunohistochemistry to detect the protein expression of p‑4E‑BP1 and phosphatase and tensin homolog (PTEN). The study identified 53 cases (59.6%) that exhibited moderate or high expression of p‑4E‑BP1 in tumor tissues, compared with little or no expression in the adjacent normal tissues. Conversely, PTEN protein expression was markedly lower in CRC compared with adjacent normal tissues. p‑4E‑BP1 protein upregulation tissues samples was consistent with PTEN downregulation in CRC samples. p‑4E‑BP1 overexpression was predominant in patients with metastasis to the regional lymph nodes. Moderate/high expression of p‑4E‑BP1 protein was significantly associated with adverse overall survival (OS) in patients. Statistical analysis using the Cox proportional hazards model, indicated that p‑4E‑BP1 expression was an independent factor suitable for predicting OS in CRC patients, which was independent of lymph node metastasis. In conclusion, p‑4E‑BP1 protein expression appears to be upregulated in CRC, suggesting that it may be a suitable biomarker for predicting CRC prognosis.

Eukaryotic translation initiation factor 4E (eIF-4E) expressions are associated with poor prognosis in colorectal adenocarcinoma

Both phosphorylated 4E binding protein 1 (p-4E-BP1) and eukaryotic translation initiation factor 4E (eIF-4E) play an important role in cancer progression. The aim of this study is to evaluate the expression of p-4E-BP1 and eIF-4E in human colorectal cancer (CRC) and to assess their clinical significance. Expression levels of two markers were analyzed in surgical specimens from 116 CRC cases by immunohistochemical staining. Their clinical significance as well as the two proteins' correlation was also investigated. Western blot was also used to detect the protein expressions in CRC cell lines. High p-4E-BP1 expression was significantly associated with lymphovascular invasion (LVI) (p=0.003), perineural invasion (PNI) (p=0.001), tumor stage (p=0.024), nodal stage (p=0.000), metastatic status (p=0.027), and disease stage (p=0.001). High eIF-4E expression had significant correlations with LVI (p=0.001), PNI (p=0.008), nodal stage (p=0.018), metastatic status (p=0.024) and disease stage (p=0.030). Pearson correlation calculations showed a weakly positive correlation between p-4E-BP1 and eIF-4E immunoreactivity (p=0.037). Patients with low eIF-4E expressions tended to have significantly longer overall survival (p=0.039). Western blot analysis showed higher expression of p-4E-BP1 and eIF-4E proteins in CRC cell lines compared with normal colon tissue. In conclusions, high expressions of eIF-4E are associated with advanced stage and poor prognosis. These data suggest that eIF-4E may provide a helpful therapeutic target in treatment of CRC.

TRAP1 downregulation in human ovarian cancer enhances invasion and epithelial-mesenchymal transition

Ovarian cancer (OC) is the second leading cause of gynecological cancer death worldwide. Although the list of biomarkers is still growing, molecular mechanisms involved in OC development and progression remain elusive. We recently demonstrated that lower expression of the molecular chaperone TRAP1 in OC patients correlates with higher tumor grade and stage, and platinum resistance. Herein we show that TRAP1 is often deleted in high-grade serous OC patients (N=579), and that TRAP1 expression is correlated with the copy number, suggesting this could be one of the driving mechanisms for the loss of TRAP1 expression in OC. At molecular level, downregulation of TRAP1 associates with higher expression of p70S6K, a kinase frequently active in OC with emerging roles in cell migration and tumor metastasis. Indeed, TRAP1 silencing in different OC cells induces upregulation of p70S6K expression and activity, enhancement of cell motility and epithelial-mesenchymal transition (EMT). Consistently, in a large cohort of OC patients, TRAP1 expression is reduced in tumor metastases and directly correlates with the epithelial marker E-Cadherin, whereas it inversely correlates with the transcription factor Slug and the matrix metallopeptidases 2 and 9. Strikingly, pharmacological inhibition of p70S6K reverts the high motility phenotype of TRAP1 knock-down cells. However, although p70S6K inhibition or silencing reduces the expression of the transcription factors Snail and Slug, thus inducing upregulation of E-Cadherin expression, it is unable to revert EMT induced by TRAP1 silencing; furthermore, p70S6K did not show any significant correlation with EMT genes in patients, nor with overall survival or tumor stage, suggesting an independent and predominant role for TRAP1 in OC progression. Altogether, these results may provide novel approaches in OC with reduced TRAP1 expression, which could be resistant to therapeutic strategies based on the inhibition of the p70S6K pathway, with potential future intervention in OC invasion and metastasis.

Judicious Toggling of mTOR Activity to Combat Insulin Resistance and Cancer: Current Evidence and Perspectives

The mechanistic target of rapamycin (mTOR), via its two distinct multiprotein complexes, mTORC1, and mTORC2, plays a central role in the regulation of cellular growth, metabolism, and migration. A dysregulation of the mTOR pathway has in turn been implicated in several pathological conditions including insulin resistance and cancer. Overactivation of mTORC1 and disruption of mTORC2 function have been reported to induce insulin resistance. On the other hand, aberrant mTORC1 and mTORC2 signaling via either genetic alterations or increased expression of proteins regulating mTOR and its downstream targets have contributed to cancer development. These underlined the attractiveness of mTOR as a therapeutic target to overcome both insulin resistance and cancer. This review summarizes the evidence supporting the notion of intermittent, low dose rapamycin for treating insulin resistance. It further highlights recent data on the continuous use of high dose rapamycin analogs and related second generation mTOR inhibitors for cancer eradication, for overcoming chemoresistance and for tumor stem cell suppression. Within these contexts, the potential challenges associated with the use of mTOR inhibitors are also discussed.

peIF4E as an independent prognostic factor and a potential therapeutic target in diffuse infiltrating astrocytomas

Malignant transformation in tumors is a complex process requiring accumulation of numerous oncogenic abnormalities. Brain tumors show considerable phenotypic and genetic heterogeneity. In a series comprising diffuse infiltrating astrocytomas (DIA) and reactive gliosis, we investigated the main factors associated with signaling pathways. We assessed expression levels and their association with tumor progression and survival. We studied 19 grade II astrocytomas, 25 anaplastic astrocytomas (grade III), 60 glioblastomas (grade IV), and 15 cases of reactive gliosis. Epidermal growth factor receptor (EGFR), pMAPK, 4E‐BP1, p4E‐BP1, pS6, eIF4E, and peIF4E expression levels were evaluated using immunohistochemistry. Expression levels were semiquantitatively evaluated using a histoscore. Immunohistochemistry and PCR were used for IDH1 mutations. Statistical analysis was based on the following tests: chi‐square, Student's t, Pearson correlation, Spearman's rho, and Mann–Whitney; ROC and Kaplan–Meier curves were constructed. A significant increase was observed between grades for expression of total and phosphorylated 4E‐BP1 and for eIF4E, Ki67, EGFR, and cyclin D1. Although expression of EGFR, eIF4E, and Ki67 correlated with survival, only peIF4E was an independent predictor of survival in the multivariate analysis. Combining the evaluation of different proteins enables us to generate helpful diagnostic nomograms. In conclusion, cell signaling pathways are activated in DIAs; peIF4E is an independent prognostic factor and a promising therapeutic target. Joint analysis of the expression of 4E‐BP1 and peIF4E could be helpful in the diagnosis of glioblastoma multiforme in small biopsy samples.

Immunohistochemical evaluation of the mTOR pathway in intra-oral minor salivary gland neoplasms

OBJECTIVES

The aim of this study was to investigate the expression of upstream and downstream molecules of the oncogenic mTOR signaling pathway in intra-oral minor salivary gland tumors (SGTs).

MATERIALS AND METHODS

Tissue samples consisted of 39 malignant and 13 benign minor SGTs, and 8 controls of normal minor salivary glands (NMSG). An immunohistochemical analysis for phosphorylated Akt, 4EBP1 and S6 (total and phosphorylated), and eIF4E was performed.

RESULTS

Expression of pAkt and 4EBP1 was observed in all SGTs and in most NMSG. p4EBP1 was detected in almost all SGT cases, NMSG being negative. S6 immunoreactivity was observed in 37.5% of NMSG, 92.3% of benign and 100% of malignant SGTs, while pS6 expression was observed in 77% of benign and 95% of malignant SGTs, but not in NMSG. Finally, eIF4E was expressed in 12.5% of NMSG, 69.2% of benign, and 76.9% of malignant tumors. All molecules studied had statistically significantly lower expression in NMSG compared with SGTs. Moreover, malignant neoplasms received higher scores compared with benign tumors for all molecules with the exception of eIF4E.

CONCLUSION

The mTOR signaling pathway is activated in SGTs, especially in malignancies. Therefore, the possible therapeutic role of targeting the mTOR pathway by rapamycin analogs in SGTs needs further investigation.

Phosphorylated 4EBP1 is associated with tumor progression and poor prognosis in Xp11.2 translocation renal cell carcinoma

Two main signaling pathways, PI3K-AKT-mTOR and RAS-MAPK, are involved in transmitting the proliferative signals which play critical roles in human cancers. However, the functions of these pathways in Xp11.2 RCC remain undefined. This study aimed to explore the expression of mTOR and MAPK cascades in Xp11.2 RCC and to assess the prognostic significance of proteins evaluated. Immunohistochemistry was performed to evaluate the expression of 4EBP1, p-4EBP1, p-mTOR, p-S6K and p-MAPK in 36 adult Xp11.2 RCC patients who were confirmed by FISH assay. Cox regression models were used to evaluate the prognostic value of all covariates. Among 36 assessed patients, 14 (38.9%), 26 (72.2%), 16 (44.4%), 19 (52.8%), and 9 (25.0%) patients showed high expression of 4EBP1, p-4EBP1, p-mTOR, p-S6K, and p-MAPK, respectively. We noted that p-4EBP1 expression was significantly correlated with lymph node metastases (P = 0.027). Multivariate analysis showed that high p-4EBP1 expression was an independent adverse prognostic factor for both PFS (HR = 33.750, P = 0.017) and OS (HR = 56.111, P = 0.026). Our findings suggest that p-4EBP1 may serve as a funnel factor that converge the upstream proliferative oncogenic signals. Effective inhibition of the pathways responsible for 4E-BP1 phosphorylation might be a useful strategy to improve the outcome of Xp11.2 RCC patients.

Integrated Analysis of PTEN and p4EBP1 Protein Expression as Predictors for pCR in HER2-Positive Breast Cancer

BACKGROUND

The PI3K/AKT pathway and phosphatase and tensin homolog (PTEN) aberrations are common in breast cancer. We investigated the correlation between phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), PTEN, p4EBP1 (phosphorylated E4 binding protein 1), and pathologic complete response (pCR) in patients receiving neoadjuvant therapy.

EXPERIMENTAL DESIGN

We retrospectively evaluated PIK3CA, PTEN, and p4EBP1 protein expression in centrally HER2-positive patients (n = 181) who received epirubicin cyclophosphamide/trastuzumab followed by docetaxel/trastuzumab alone or concomitant/followed by capecitabine within the GeparQuattro study. PTEN was assessed using the automated quantitative immunofluorescence analysis and was analyzed as a dichotomic variable. p4EBP1 was assessed by immunohistochemistry and used as a continuous and dichotomic variable.

RESULTS

p4EBP1 was available from 137, PTEN from 108, and PIK3CA genotype from 83 patients. Overall, the pCR rate in PTEN-low tumors was 27.6%, and in PTEN-high tumors, it was 57.1% (P = 0.010). pCR rates were not statistically different between PIK3CA wild-type and mutant (35% vs. 22%) or p4EBP1 IRS ≤ 4 and IRS > 4 (39% vs. 33%). pCR rate was 57.1% (8/14) in PTEN-high/PIK3CA wild-type and decreased to 15.4% in PTEN-low/PIK3CA-mutant tumors (P = 0.023). In multivariable analysis adjusted for baseline parameters, PTEN independently predicted pCR in the following cohorts: overall [OR, 7.54; 95% confidence interval (CI), 2.03-28.06; P = 0.003], PIK3CA wild-type (OR, 23.81; 95% CI, 1.75-324.05; P = 0.017), p4EBP1 IRS > 4 (OR, 11.53; 95% CI, 1.84-72.24; P = 0.009), and hormone receptor-positive (OR, 40.91; 95% CI, 2.93-570.44; P = 0.006). p4EBP1 was independently predictive for pCR in PIK3CA wild-type tumors (OR, 0.14; 95% CI, 0.03-0.78; P = 0.025).

CONCLUSIONS

The study showed the potential role of PIK3CA genotype, PTEN, and p4EBP in predicting pCR after anthracycline-taxane-based chemotherapy and anti-HER2 treatment. Clin Cancer Res; 22(11); 2675-83. ©2016 AACR.

RAS/MAPK pathway hyperactivation determines poor prognosis in undifferentiated pleomorphic sarcomas

BACKGROUND

Undifferentiated pleomorphic sarcoma (UPS) constitutes the most common subtype of soft tissue sarcoma. However, UPS is clinically and molecularly poorly understood, in great extent due to its intrinsic phenotypic and cytogenetic complexity, which in turn results in the absence of specific prognostic or predictive biomarkers. The RAS/mitogen-activated protein kinases (MAPK) and phosphoinositide 3-kinase inhibitor (PI3K)/mammalian target of rapamycin (mTOR) pathways are considered to be 2 major mechanisms for sarcoma proliferation and survival and to the authors' knowledge their role in UPS remains unclear. The objective of the current study was to investigate whether the RAS/MAPK and PI3K/mTOR pathways are activated in UPS, and whether pathway activation is associated with outcome.

METHODS

Records for patients diagnosed and treated for UPS in the study institution between 2000 and 2009 were reviewed. Phosphorylation status of 4E-binding protein (4E-BP1), eukaryotic translation initiation factor 4E (eIF-4E), S6-RP, and ERK 1/2, together with total forms of 4E-BP1 and eIF-4E, were assessed using immunohistochemistry in paraffin-embedded tumor tissue. Mutational analysis for KRAS; NRAS; BRAF; and phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) oncogenic mutations was performed as well.

RESULTS

Critical lymph nodes within the RAS/MAPK and PI3K/mTOR pathways were found to be activated in >80% of UPS cases. Hyperactivation of the RAS/MAPK pathway, as assessed by expression of phosphorylated ERK 1/2, was found to independently predict a higher risk of disease recurrence and impaired overall survival. Only a KRAS A146V mutation was detected in 1 tumor.

CONCLUSIONS

The RAS/MAPK and PI3K/mTOR pathways are activated in the majority of cases of UPS. The RAS/MAPK pathway distinguishes a subgroup of patients with localized UPS with a worse outcome.

Knockdown of eIF4E suppresses cell proliferation, invasion and enhances cisplatin cytotoxicity in human ovarian cancer cells

Eukaryotic initiation factor 4E (eIF4E) plays an important role in cap-dependent translation. The overexpression of eIF4E gene has been found in a variety of human malignancies. In this study, we attempted to identify the potential effects of eIF4E and explore the possibility of eIF4E as a therapeutic target for the treatment of human ovarian cancer. First the activation of eIF4E protein was detected with m7-GTP cap binding assays in ovarian cancer and control cells. Next, the eIF4E-shRNA expression plasmids were used to specifically inhibit eIF4E activity in ovarian cancer cells line A2780 and C200. The effects of knockdown eIF4E gene on cell proliferation, migration and invasion were investigated in vitro. Moreover, the changes of cell cycle and apoptosis of ovarian cancer cells were detected by flow cytometry. Finally, we investigated the effect of knockdown of eIF4E on the chemosensitivity of ovarian cancer cells to cisplatin in vitro. Our results show there is elevated activation of eIF4E in ovarian cancer cells compared with normal human ovarian epithelial cell line. The results of BrdU incorporation and FCM assay indicate that knockdown of eIF4E efficiently suppressed cell growth and induce cell cycle arrest in G1 phase and subsequent apoptosis in ovarian cancer cells. From Transwell assay analysis, knockdown eIF4E significantly decrease cellular migration and invasion of ovarian cancer cells. We also confirmed that knockdown eIF4E could synergistically enhance the cytotoxicity effects of cisplatin to cancer cells and sensitized cisplatin-resistant C200 cells in vitro. This study demonstrates that the activation of eIF4E gene is an essential component of the malignant phenotype in ovarian cancer, and aberration of eIF4E expression is associated with proliferation, migration, invasion and chemosensitivity to cisplatin in ovarian cancer cells. Knockdown eIF4E gene can be used as a potential therapeutic target for the treatment of human ovarian cancer.

Phosphorylated 4E-binding protein 1 expression is associated with poor prognosis in small-cell lung cancer

Phosphorylation of eukaryotic translation initiation factor 4E (eIF4E) binding protein (4E-BP1) results in release of eIF4E, which sequentially relieves translational repression and enhances oncogenic protein synthesis. We assessed the expression of phosphorylated 4E-BP1 (p-4E-BP1) in small-cell lung cancer (SCLC) and its correlation with clinicopathological factors and patient survival. This study included 117 SCLCs, which comprised 108 primary and 9 metastatic tumor tissues. We performed immunohistochemical staining for p-4E-BP1 in 117 tumors and found that 77 (66 %) were positive for p-4E-BP1 with cytoplasmic and/or nuclear immunostaining. The positive rate of p-4E-BP1 staining was significantly higher in never smokers (p = 0.034) and metastatic tumor tissues (p = 0.027). Patients with p-4E-BP1-positive SCLC tended to have poor performance status, although the difference was not statistically significant (p = 0.087). High p-4E-BP1 expression was significantly correlated with worse overall survival (OS) in all cohorts (p = 0.016). After stratification by clinical stage, p-4E-BP1 expression showed a stronger relationship with OS in patients with limited disease (p = 0.008). In addition, when stratified by treatment status, p-4E-BP1 expression was still significantly associated with worse OS in a subgroup of patients who completed treatment (p = 0.021). Our results indicate that p-4E-BP1 expression could represent oncogenic potential and contribute to the progression and aggressiveness of SCLC, suggesting it could be a candidate prognostic biomarker of SCLC, especially in limited disease.

Toward rapamycin analog (rapalog)-based precision cancer therapy

Rapamycin and its analogs (rapalogs) are the first generation of mTOR inhibitors, which have the same molecular scaffold, but different physiochemical properties. Rapalogs are being tested in a wide spectrum of human tumors as both monotherapy and a component of combination therapy. Among them, temsirolimus and everolimus have been approved for the treatment of breast and renal cancer. However, objective response rates with rapalogs in clinical trials are modest and variable. Identification of biomarkers predicting response to rapalogs, and discovery of drug combinations with improved efficacy and tolerated toxicity are critical to moving this class of targeted therapeutics forward. This review focuses on the aberrations in the PI3K/mTOR pathway in human tumor cells or tissues as predictive biomarkers for rapalog efficacy. Recent results of combinational therapy using rapalogs and other anticancer drugs are documented. With the rapid development of next-generation genomic sequencing and precision medicine, rapalogs will provide greater benefits to cancer patients.

p70 S6 kinase drives ovarian cancer metastasis through multicellular spheroid-peritoneum interaction and P-cadherin/b1 integrin signaling activation

Peritoneal dissemination as a manifestation of ovarian cancer is an adverse prognostic factor associated with poor clinical outcome, and is thus a potentially promising target for improved treatment. Sphere forming cells (multicellular spheroids) present in malignant ascites of patients with ovarian cancer represent a major impediment to effective treatment. p70 S6 kinase (p70^S6K), which is a downstream effector of mammalian target of rapamycin, is frequently hyperactivated in human ovarian cancer. Here, we identified p70^S6K as an important regulator for the seeding and successful colonization of ovarian cancer spheroids on the peritoneum. Furthermore, we provided evidence for the existence of a novel crosstalk between P-cadherin and β1 integrin, which was crucial for the high degree of specificity in cell adhesion. In particular, we demonstrated that the upregulation of mature β1 integrin occurred as a consequence of P-cadherin expression through the induction of the Golgi glycosyltransferase, ST6Gal-I, which mediated β1 integrin hypersialylation. Loss of p70^S6K or targeting the P-cadherin/β1-integrin interplay could significantly attenuate the metastatic spread onto the peritoneum in vivo. These findings establish a new role for p70^S6K in tumor spheroid-mesothelium communication in ovarian cancer and provide a preclinical rationale for targeting p70^S6K as a new avenue for microenvironment-based therapeutic strategy.

Ribosomal proteins as novel players in tumorigenesis

Ribosome biogenesis is the most demanding energetic and metabolic expenditure of the cell. The nucleolus, a nuclear compartment, coordinates rRNA transcription, maturation, and assembly into ribosome subunits. The transcription process is highly coordinated with ribosome biogenesis. In this context, ribosomal proteins (RPs) play a crucial role. In the last decade, an increasing number of studies have associated RPs with extraribosomal functions related to proliferation. Importantly, the expression of RPs appears to be deregulated in several human disorders due, at least in part, to genetic mutations. Although the deregulation of RPs in human malignancies is commonly observed, a more complex mechanism is believed to be involved, favoring the tumorigenic process, its progression and metastasis. This review explores the roles of the most frequently mutated oncogenes and tumor suppressor genes in human cancer that modulate ribosome biogenesis, including their interaction with RPs. In this regard, we propose a new focus for novel therapies.

S6 kinase signaling: tamoxifen response and prognostic indication in two breast cancer cohorts

Detection of signals in the mammalian target of rapamycin (mTOR) and the estrogen receptor (ER) pathways may be a future clinical tool for the prediction of adjuvant treatment response in primary breast cancer. Using immunohistological staining, we investigated the value of the mTOR targets p70-S6 kinase (S6K) 1 and 2 as biomarkers for tamoxifen benefit in two independent clinical trials comparing adjuvant tamoxifen with no tamoxifen or 5 years versus 2 years of tamoxifen treatment. In addition, the prognostic value of the S6Ks was evaluated. We found that S6K1 correlated with proliferation, HER2 status, and cytoplasmic AKT activity, whereas high protein expression levels of S6K2 and phosphorylated (p) S6K were more common in ER-positive, and low-proliferative tumors with pAKT-s473 localized to the nucelus. Nuclear accumulation of S6K1 was indicative of a reduced tamoxifen effect (hazard ratio (HR): 1.07, 95% CI: 0.53-2.81, P=0.84), compared with a significant benefit from tamoxifen treatment in patients without tumor S6K1 nuclear accumulation (HR: 0.42, 95% CI: 0.29-0.62, P<0.00001). Also S6K1 and S6K2 activation, indicated by pS6K-t389 expression, was associated with low benefit from tamoxifen (HR: 0.97, 95% CI: 0.50-1.87, P=0.92). In addition, high protein expression of S6K1, independent of localization, predicted worse prognosis in a multivariate analysis, P=0.00041 (cytoplasm), P=0.016 (nucleus). In conclusion, the mTOR-activated kinases S6K1 and S6K2 interfere with proliferation and response to tamoxifen. Monitoring their activity and intracellular localization may provide biomarkers for breast cancer treatment, allowing the identification of a group of patients less likely to benefit from tamoxifen and thus in need of an alternative or additional targeted treatment.

Phosphorylation of eIF4E Confers Resistance to Cellular Stress and DNA-Damaging Agents through an Interaction with 4E-T: A Rationale for Novel Therapeutic Approaches

Phosphorylation of the eukaryotic translation initiation factor eIF4E is associated with malignant progression and poor cancer prognosis. Accordingly, here we have analyzed the association between eIF4E phosphorylation and cellular resistance to oxidative stress, starvation, and DNA-damaging agents in vitro. Using immortalized and cancer cell lines, retroviral expression of a phosphomimetic (S209D) form of eIF4E, but not phospho-dead (S209A) eIF4E or GFP control, significantly increased cellular resistance to stress induced by DNA-damaging agents (cisplatin), starvation (glucose+glutamine withdrawal), and oxidative stress (arsenite). De novo accumulation of eIF4E-containing cytoplasmic bodies colocalizing with the eIF4E-binding protein 4E-T was observed after expression of phosphomimetic S209D, but not S209A or wild-type eIF4E. Increased resistance to cellular stress induced by eIF4E-S209D was lost upon knockdown of endogenous 4E-T or use of an eIF4E-W73A-S209D mutant unable to bind 4E-T. Cancer cells treated with the Mnk1/2 inhibitor CGP57380 to prevent eIF4E phosphorylation and mouse embryonic fibroblasts derived from Mnk1/2 knockout mice were also more sensitive to arsenite and cisplatin treatment. Polysome analysis revealed an 80S peak 2 hours after arsenite treatment in cells overexpressing phosphomimetic eIF4E, indicating translational stalling. Nonetheless, a selective increase was observed in the synthesis of some proteins (cyclin D1, HuR, and Mcl-1). We conclude that phosphorylation of eIF4E confers resistance to various cell stressors and that a direct interaction or regulation of 4E-T by eIF4E is required. Further delineation of this process may identify novel therapeutic avenues for cancer treatment, and these results support the use of modern Mnk1/2 inhibitors in conjunction with standard therapy.

High expression of neuroguidin increases the sensitivity of acute myeloid leukemia cells to chemotherapeutic drugs

Neuroguidin (NGDN) is a eukaryotic translation initiation factor 4E binding protein. The purpose of this study was to clarify the function of NGDN and its possible mechanism of action in human myeloid leukemia cells. Proliferation inhibition and apoptosis in NGDN over-expressing myeloid multidrug-resistant leukemia cells (K562/A02-NGDN) was significantly higher than in control K562/A02 cells following treatment with vincristine, etoposide, and epirubicin, indicating that NGDN over-expression can increase the sensitivity of multidrug-resistant leukemia cells to chemotherapeutic drugs. Furthermore, NGDN knock-down in K562/A02 cells resulted in the activation of multiple tumor-related signaling pathways, especially the mammalian target of rapamycin (mTOR) pathway.

EIF4EBP1 overexpression is associated with poor survival and disease progression in patients with hepatocellular carcinoma

Objective

EIF4EBP1 acts as a crucial effector in mTOR signaling pathway. Studies have suggested that EIF4EBP1 plays a critical role in carcinogenesis. However, the clinical significance and biological role of EIF4EBP1 in hepatocellular carcinoma (HCC) have not been elucidated. Therefore, we aimed to investigate the clinical significance of EIF4EBP1 in HCC.

Methods

Total 128 cases of HCCs were included in this study. EIF4EBP1 expression in HCC tissues was detected by qRT-PCR, Western blot and immunohistochemistry, respectively. Then the relationships between EIF4EBP1 expression and clinical features as well as survival were analyzed.

Results

The expression level of EIF4EBP1 mRNA is significantly higher in 60% (24/40) of fresh HCC tissues than that in the matched adjacent nontumor liver (NCL) tissues (P = 0.044). Similarly, EIF4EBP1 protein is notably upregulated in 8 HCC tissues (randomly selected from the 40 HCCs) measured by Western blot and is significantly increased in another 88 paraffin-embedded HCCs (53%, 47/88) by immunohistochemistry compared with the matched NCLs (P < 0.001). EIF4EBP1 protein expression in HCC tissues is significantly correlated with serum AFP (P = 0.003) and marginally significantly associated with pathological grade (P = 0.085), tumor number (P = 0.084), tumor embolus (P = 0.084) and capsulation (P = 0.073). Patients with higher EIF4EBP1 protein expression have a much worse 5-year overall survival (40.3% vs 73.6%) and 5-year disease-free survival (33.0% vs 49.0%) than those with low expression. Furthermore, Cox regression analysis shows that EIF4EBP1 protein is an independent prognostic factor for overall survival (HR, 2.285; 95% CI, 1.154–4.527; P = 0.018) and disease-free survival (HR, 1.901; 95% CI, 1.067–3.386; P = 0.029) in HCC patients.

Conclusions

Our results demonstrate for the first time that EIF4EBP1 mRNA and protein are markedly up-regulated in HCC tissues, and the protein overexpression is significantly associated with poor survival and progression, which provide a potential new prognostic marker and therapeutic target for HCC patients.

Overexpression of phosphorylated 4E-binding protein 1 and its clinicopathological significances in gastric cancer

Multiple intracellular transforming signals regulate eukaryotic translation initiation factor 4E (eIF4E)-binding protein (4E-BP1). The signals result in hierarchical phosphorylation of 4E-BP1, resulting in release of eIF4E, relieving translational repression and enhancing oncogenic protein synthesis. This study assessed the expression of phosphorylated 4E-BP1 (p-4E-BP1) in gastric cancer and its correlation with clinicopathological parameters and patient survival. Tissue microarray blocks were generated from 179 gastric carcinomas and immunohistochemically stained for p-4E-BP1. The expression of p-4E-BP1 was higher in tumors that were intestinal-type (P=0.028); had a diameter smaller than 5cm (P=0.001); were lower pathological T stage (P<0.001), N stage (P=0.004), or TNM stage (P<0.001); did not have distant metastasis (P=0.027). High p-4E-BP1 expression significantly correlated with prolonged overall survival (P=0.046) and disease-free survival (P=0.035), but was not an independent prognostic factor in multivariate analysis. Our results indicate that p-4E-BP1 is more highly expressed in early gastric cancers than in advanced ones, and has limited potential as an independent prognostic biomarker in patients with gastric cancer. Larger well-controlled studies with molecular validation are warranted to elucidate more exact prognostic significance and working mechanism of p-4E-BP1 in gastric cancer.

Significance of 4E-binding protein 1 as a therapeutic target for invasive urothelial carcinoma of the bladder

BACKGROUND

To evaluate the expression of multiple molecular markers involved in the mammalian target of rapamycin (mTOR) signaling pathway in human muscle-invasive bladder cancer (BC) and to assess the therapeutic efficacies of mTOR inhibitors in human BC KoTCC-1 cells.

METHODS

Expression levels of 5 markers, including PTEN, phosphorylated (p)-Akt, p-mTOR, p-p70 ribosomal S6 kinase, and p-4E-binding protein 1 (4E-BP1), were measured in radical cystectomy specimens from 49 patients with muscle-invasive BC by immunohistochemical staining. We then analyzed the effects of treatment with temsirolimus or Ku-0063794, a dual inhibitor of mTOR complex 1 (C1) and mTOR complex 2 (C2), on changes in the growth and expression profiles of 5 mTOR-associated markers in KoTCC-1 cells.

RESULTS

During the follow-up period of this study, disease recurred in 27 patients (55.1%), and of several factors examined, the expression level of p-4E-BP1 in addition to the pathological T stage was independently related to recurrence-free survival on multivariate analysis. Although the growth of KoTCC-1 cells was inhibited by both temsirolimus and Ku-0063794 in dose-dependent manners, treatment with Ku-0063794 resulted in a marked decrease in the expression of p-4E-BP1 in KoTCC-1 cells compared with that with temsirolimus. Furthermore, the growth-inhibitory effect of both mTOR inhibitors was shown to be proportional to the expression levels of p-4E-BP1.

CONCLUSIONS

The phosphorylation status of 4E-BP1 appeared to be correlated with the prognosis of patients with muscle-invasive BC following radical cystectomy as well as the sensitivities of BC cells to mTOR inhibitors; therefore, the inactivation of 4E-BP1 using Ku-0063794 may be a promising novel approach for muscle-invasive BC.

The mTOR effectors 4EBP1 and S6K2 are frequently coexpressed, and associated with a poor prognosis and endocrine resistance in breast cancer: a retrospective study including patients from the randomised Stockholm tamoxifen trials

Introduction

mTOR and its downstream effectors the 4E-binding protein 1 (4EBP1) and the p70 ribosomal S6 kinases (S6K1 and S6K2) are frequently upregulated in breast cancer, and assumed to be driving forces in tumourigenesis, in close connection with oestrogen receptor (ER) networks. Here, we investigated these factors as clinical markers in five different cohorts of breast cancer patients.

Methods

The prognostic significance of 4EBP1, S6K1 and S6K2 mRNA expression was assessed with real-time PCR in 93 tumours from the treatment randomised Stockholm trials, encompassing postmenopausal patients enrolled between 1976 and 1990. Three publicly available breast cancer cohorts were used to confirm the results. Furthermore, the predictive values of 4EBP1 and p4EBP1_S65 protein expression for both prognosis and endocrine treatment benefit were assessed by immunohistochemical analysis of 912 node-negative breast cancers from the Stockholm trials.

Results

S6K2 and 4EBP1 mRNA expression levels showed significant correlation and were associated with a poor outcome in all cohorts investigated. 4EBP1 protein was confirmed as an independent prognostic factor, especially in progesterone receptor (PgR)-expressing cancers. 4EBP1 protein expression was also associated with a poor response to endocrine treatment in the ER/PgR positive group. Cross-talk to genomic as well as non-genomic ER/PgR signalling may be involved and the results further support a combination of ER and mTOR signalling targeted therapies.

Conclusion

This study suggests S6K2 and 4EBP1 as important factors for breast tumourigenesis, interplaying with hormone receptor signalling. We propose S6K2 and 4EBP1 as new potential clinical markers for prognosis and endocrine therapy response in breast cancer.

Activation of Akt/mTOR pathway is associated with poor prognosis of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumor of the head and neck region, which frequently occurs in Southeast Asia, especially in the south of China. It is known that the mammalian target of rapamycin (mTOR) pathway plays a central role in regulating cellular functions, including proliferation, growth, survival, mobility, and angiogenesis. Aberrant expression of the mTOR signaling pathway molecules has been found in many types of cancer. However, whether the alterations of p-Akt, p-p70S6K and p-4EBP1 protein expression are associated with clinicopathological features and prognostic implications in NPC have not been reported. The purposes of the present study are to investigate the association between the expression of p-Akt, p-p70S6K and p-4EBP1 proteins and clinicopathological features in NPC by immunohistochemistry. The results showed that the positive percentage of p-Akt, p-p70S6K and p-4EBP1 proteins expression in NPC (47.2%, 73.0% and 61.7%, respectively) was significantly higher than that in the non-cancerous nasopharyngeal control tissue (33.3%, 59.1% and 47.0%, respectively). There was a significantly higher positive expression of p-Akt in undifferentiated non-keratinizing nasopharyngeal carcinoma than that in differentiated non-keratinizing nasopharyngeal carcinoma (P = 0.014). Additionally, positive expression of p-p70S6K and p-4EBP1 proteins, and positive expression of either of p-Akt, p-p70S6K and p-4EBP1 were significantly correlated inversely with overall survival rates of NPC patients (P = 0.023, P = 0.033, P = 0.008, respectively). Spearman’s rank correlation test showed that expression of p-Akt in NPC was significantly associated with expression of p-p70S6K (r = 0.263, P<0.001) and p-4EBP1(r = 0.284, P<0.001). Also there was an obviously positive association between expression of p-p70S6K and p-4EBP1 proteins in NPC (r = 0.286, P<0.001). Multivariate Cox regression analysis further identified positive expression of p-4EBP1 and p-p70S6K proteins were the independent poor prognostic factors for NPC (P = 0.043, P = 0.027, respectively). Taken together, high expression of p-p70S6K and p-4EBP1 proteins may act as valuable independent biomarkers to predict a poor prognosis of NPC.