Nuclear PRAS40 couples the Akt/mTORC1 signaling axis to the RPL11-HDM2-p53 nucleolar stress response pathway

Nuclear mTOR Signaling Orchestrates Transcriptional Programs Underlying Cellular Growth and Metabolism

mTOR is a central regulator of cell growth and metabolism in response to mitogenic and nutrient signals. Notably, mTOR is not only found in the cytoplasm but also in the nucleus. This review highlights direct involvement of nuclear mTOR in regulating transcription factors, orchestrating epigenetic modifications, and facilitating chromatin remodeling. These effects intricately modulate gene expression programs associated with growth and metabolic processes. Furthermore, the review underscores the importance of nuclear mTOR in mediating the interplay between metabolism and epigenetic modifications. By integrating its functions in nutrient signaling and gene expression related to growth and metabolism, nuclear mTOR emerges as a central hub governing cellular homeostasis, malignant transformation, and cancer progression. Better understanding of nuclear mTOR signaling has the potential to lead to novel therapies against cancer and other growth-related diseases.

Stage-specific regulation of undifferentiated spermatogonia by AKT1S1-mediated AKT-mTORC1 signaling during mouse spermatogenesis

Undifferentiated spermatogonia are composed of a heterogeneous cell population including spermatogonial stem cells (SSCs). Molecular mechanisms underlying the regulation of various spermatogonial cohorts during their self-renewal and differentiation are largely unclear. Here we show that AKT1S1, an AKT substrate and inhibitor of mTORC1, regulates the homeostasis of undifferentiated spermatogonia. Although deletion of Akt1s1 in mouse appears not grossly affecting steady-state spermatogenesis and male mice are fertile, the subset of differentiation-primed OCT4+ spermatogonia decreased significantly, whereas self-renewing GFRα1+ and proliferating PLZF+ spermatogonia were sustained. Both neonatal prospermatogonia and the first wave spermatogenesis were greatly reduced in Akt1s1-/- mice. Further analyses suggest that OCT4+ spermatogonia in Akt1s1-/- mice possess altered PI3K/AKT-mTORC1 signaling, gene expression and carbohydrate metabolism, leading to their functionally compromised developmental potential. Collectively, these results revealed an important role of AKT1S1 in mediating the stage-specific signals that regulate the self-renewal and differentiation of spermatogonia during mouse spermatogenesis.

Spatial resolution of cellular senescence dynamics in human colorectal liver metastasis

Hepatic metastasis is a clinical challenge for colorectal cancer (CRC). Senescent cancer cells accumulate in CRC favoring tumor dissemination. Whether this mechanism progresses also in metastasis is unexplored. Here, we integrated spatial transcriptomics, 3D-microscopy, and multicellular transcriptomics to study the role of cellular senescence in human colorectal liver metastasis (CRLM). We discovered two distinct senescent metastatic cancer cell (SMCC) subtypes, transcriptionally located at the opposite pole of epithelial (e) to mesenchymal (m) transition. SMCCs differ in chemotherapy susceptibility, biological program, and prognostic roles. Mechanistically, epithelial (e)SMCC initiation relies on nucleolar stress, whereby c-myc dependent oncogene hyperactivation induces ribosomal RPL11 accumulation and DNA damage response. In a 2D pre-clinical model, we demonstrated that RPL11 co-localized with HDM2, a p53-specific ubiquitin ligase, leading to senescence activation in (e)SMCCs. On the contrary, mesenchymal (m)SMCCs undergo TGFβ paracrine activation of NOX4-p15 effectors. SMCCs display opposing effects also in the immune regulation of neighboring cells, establishing an immunosuppressive environment or leading to an active immune workflow. Both SMCC signatures are predictive biomarkers whose unbalanced ratio determined the clinical outcome in CRLM and CRC patients. Altogether, we provide a comprehensive new understanding of the role of SMCCs in CRLM and highlight their potential as new therapeutic targets to limit CRLM progression.

P53 protein and the diseases in central nervous system

P53 protein is the product of P53 gene, which is a well acknowledged tumor suppressor gene. The function of P53 and the relevant mechanisms of anti-neoplasm have raised the interest of researchers since many years ago. It is demonstrated that P53 is a basic cell cycle regulator and a strong inhibitor for versatile cancers in humans. However, most research focuses on other organs and systems instead of the central nervous system (CNS). In fact, in recent years, more and more studies have been suggesting that P53 plays a significant role in multiple CNS tumors and other diseases and disorders such as cerebral stroke and neurodegenerative diseases. In this work, we mainly reviewed the P53's relationship with CNS tumors, cerebral stroke and neurodegenerative diseases, together with the relevant mechanisms, aiming to summarize the research achievements and providing new insight to the future study on diseases in CNS.

Investigation of the anti-tumor mechanism of tirabrutinib, a highly selective Bruton's tyrosine kinase inhibitor, by phosphoproteomics and transcriptomics

Tirabrutinib is a highly selective Bruton's tyrosine kinase (BTK) inhibitor used to treat hematological malignancies. We analyzed the anti-tumor mechanism of tirabrutinib using phosphoproteomic and transcriptomic methods. It is important to check the drug's selectivity against off-target proteins to understand the anti-tumor mechanism based on the on-target drug effect. Tirabrutinib's selectivity was evaluated by biochemical kinase profiling assays, peripheral blood mononuclear cell stimulation assays, and the BioMAP system. Next, in vitro and in vivo analyses of the anti-tumor mechanisms were conducted in activated B-cell-like diffuse large B-cell lymphoma (ABC-DLBCL) cells followed by phosphoproteomic and transcriptomic analyses. In vitro kinase assays showed that, compared with ibrutinib, tirabrutinib and other second-generation BTK inhibitors demonstrated a highly selective kinase profile. Data from in vitro cellular systems showed that tirabrutinib selectively affected B-cells. Tirabrutinib inhibited the cell growth of both TMD8 and U-2932 cells in correlation with the inhibition of BTK autophosphorylation. Phosphoproteomic analysis revealed the downregulation of ERK and AKT pathways in TMD8. In the TMD8 subcutaneous xenograft model, tirabrutinib showed a dose-dependent anti-tumor effect. Transcriptomic analysis indicated that IRF4 gene expression signatures had decreased in the tirabrutinib groups. In conclusion, tirabrutinib exerted an anti-tumor effect by regulating multiple BTK downstream signaling proteins, such as NF-κB, AKT, and ERK, in ABC-DLBCL.

Rheb regulates nuclear mTORC1 activity independent of farnesylation

The small GTPase Ras homolog enriched in brain (Rheb) plays a critical role in activating the mechanistic target of rapamycin complex 1 (mTORC1), a signaling hub that regulates various cellular functions. We recently observed nuclear mTORC1 activity, raising an intriguing question as to how Rheb, which is known to be farnesylated and localized to intracellular membranes, regulates nuclear mTORC1. In this study, we found that active Rheb is present in the nucleus and required for nuclear mTORC1 activity. We showed that inhibition of farnesyltransferase reduced cytosolic, but not nuclear, mTORC1 activity. Furthermore, a farnesylation-deficient Rheb mutant, with preferential nuclear localization and specific lysosome tethering, enables nuclear and cytosolic mTORC1 activities, respectively. These data suggest that non-farnesylated Rheb is capable of interacting with and activating mTORC1, providing mechanistic insights into the molecular functioning of Rheb as well as regulation of the recently observed, active pool of nuclear mTORC1.

PGK1 represses autophagy-mediated cell death to promote the proliferation of liver cancer cells by phosphorylating PRAS40

Autophagy predominantly promotes cell survival by recycling cell components, while it kills cells in specific contexts. Cell death related to autophagy plays important roles in multiple physiological and pathological situations including tumorigenesis, and the mechanism needs to be defined further. PRAS40 was found to be crucial in various cancers, and phosphorylation was reported to be involved in autophagy inhibition in monocytes. However, the detailed role of PRAS40 in autophagy and the relationship to tumorigenesis remain largely unknown. Herein we screened the binding partners of PRAS40, and found that PRAS40 interacted with Phosphoglycerate kinase 1 (PGK1). PGK1 phosphorylated PRAS40 at Threonine 246, which could be inhibited by blocking the interaction. Both in vitro and in vivo results revealed that PRAS40 mediated PGK1-induced cell growth. By tracing the mechanism, we found that PGK1 suppressed autophagy-mediated cell death, in which PRAS40 was crucial. Thus PGK1 phosphorylates PRAS40 to repress autophagy-mediated cell death under normoxia, promoting cellular proliferation. The binding of PGK1 to PRAS40 was transferred to Beclin1 under hypoxia, resulting in the increase of Beclin1 phosphorylation. These results suggest a novel model of tumorigenesis, in which PGK1 switches between repressing autophagy-mediated cell death via PRAS40 and inducing autophagy through Beclin1 according to the environmental oxygen level. Our study is anticipated to be able to offer novel insights in understanding PGK1/PRAS40 signaling hyperactivated cancers.

p53 Inhibition Protects against Neuronal Ischemia/Reperfusion Injury by the p53/PRAS40/mTOR Pathway

The underlying mechanisms of cerebral ischemia/reperfusion (I/R) injury are unclear. Within this study, we aimed to explore whether p53 inhibition exerts protective effects via the p53/PRAS40/mTOR pathway after stroke and its potential mechanism. Both an in vitro oxygen-glucose deprivation (OGD) model with a primary neuronal culture and in vivo stroke models (dMCAO or MCAO) were used. We found that the infarction size, neuronal apoptosis, and autophagy were less severe in p53 KO mice and p53 KO neurons after cerebral I/R or OGD/R injury. By activating the mTOR pathway, p53 knockdown alleviated cerebral I/R injury both in vitro and in vivo. When PRAS40 was knocked out, the regulatory effects of p53 overexpression or knockdown against stroke disappeared. PRAS40 knockdown could inhibit the activities of the mTOR pathway; moreover, neuronal autophagy and apoptosis were exacerbated by PRAS40 knockdown. To sum up, in this study, we showed p53 inhibition protects against neuronal I/R injury after stroke via the p53/PRAS40/mTOR pathway, which is a novel and pivotal cerebral ischemic injury signaling pathway. The induction of neuronal autophagy and apoptosis by the p53/PRAS40/mTOR pathway may be the potential mechanism of this protective effect.

Phosphoinositide 3-kinase signalling in the nucleolus

The phosphoinositide 3-kinase (PI3K) signalling pathway plays key roles in many cellular processes and is altered in many diseases. The function and mode of action of the pathway have mostly been elucidated in the cytoplasm. However, many of the components of the PI3K pathway are also present in the nucleus at specific sub-nuclear sites including nuclear speckles, nuclear lipid islets and the nucleolus. Nucleoli are membrane-less subnuclear structures where ribosome biogenesis occurs. Processes leading to ribosome biogenesis are tightly regulated to maintain protein translation capacity of cells. This review focuses on nucleolar PI3K signalling and how it regulates rRNA synthesis, as well as on the identification of downstream phosphatidylinositol (3,4,5)trisphosphate effector proteins.

Epigenetic alterations induced by aflatoxin B1: An in vitro and in vivo approach with emphasis on enhancer of zeste homologue-2/p21 axis

The potent environmental toxicant aflatoxin B₁ (AFB₁), is a group I carcinogen reported to induce the expression of many cancer associated proteins. Epigenetic alterations such as DNA methylation and histone modifications play vital role in AFB₁-mediated carcinogenesis. These epigenetic modifications may result in the recruitment of specific proteins and transcription factors to the promoter region and regulate gene expression. Here we show that AFB₁, at lower concentrations (100 and 1000 nM) induced proliferation in L-132 and HaCaT cells with activation of the Akt pathway, which ultimately steered abnormal proliferation and transmission of survival signals. We demonstrated a significant reduction in the expression of p21 with a remarkable increase in the expression of cyclin D1 that correlated with increased methylation of CpG dinucleotides in p21 proximal promoter, while cyclin D1 promoter remained unmethylated. The chromatin immunoprecipitation results revealed the enrichment of DNMT3a and H3K27me3 repressive marks on the p21 proximal promoter where EZH2 mediated H3K27me3 mark enhanced the binding of DNMT3a at the promoter and further contributed to the transcriptional inactivation. The overall study provided the novel information on the impact of AFB₁ on p21 inactivation via EZH2 and promoter methylation which is known to be a vital process in proliferation. Furthermore, AFB₁ induced the expression of EZH2 analogue protein E(z), cyclin D1 analogue cyclin D and decreased the expression of p21 analogue Dacapo in Drosophila melanogaster. Interestingly, the aggressiveness in their expression upon re-exposure in successive generations suggested first hand perspectives on multigenerational epigenetic memory.

The Molecular Landscape and Biological Alterations Induced by PRAS40-Knockout in Head and Neck Squamous Cell Carcinoma

PRAS40 (Prolin-rich Akt substrate of 40 kDa) is a critical protein, which directly connects PI3K/Akt and mTORC1 pathway. It plays an indispensable role in the development of various diseases. However, the relationship between PRAS40 and head and neck squamous cell carcinoma (HNSCC) remains unclear. Here, our study indicated that high expression of PRAS40 mRNA is a favorable prognostic factor in HNSCC patients by analyzing 498 clinical and mRNA data. Moreover, we confirmed that CRISPR/Cas9 induced PRAS40-knockout would promote colony formation, cell migration, and invasion in several HNSCC cell lines. RNA-seq was employed to investigate the further possible mechanisms involving the above regulations by PRAS40 in HNSCC cells. The molecular landscape contributed by 253 differentially expressed mRNA after PRAS40-knockout was enriched in TGF-beta, PI3K-Akt, P53, mTOR, NF-κB signaling pathway. Partial molecular alternations within these pathways were validated by qPCR or Western blotting. Besides, we found that high expression of PRAS40 in HNSC patients would present more CD8⁺ T and T follicular helper cells, but less Th17 cells than the patients with low expression of PRAS40. The altered molecular pathways and tumor-infiltrating immune cells might associate with the mechanism of PRAS40 being a suppressor in HNSCC cells, which would provide a potential prognostic predictor and therapeutic target in HNSCC patients.

Location-specific inhibition of Akt reveals regulation of mTORC1 activity in the nucleus

The mechanistic target of rapamycin complex 1 (mTORC1) integrates growth, nutrient and energy status cues to control cell growth and metabolism. While mTORC1 activation at the lysosome is well characterized, it is not clear how this complex is regulated at other subcellular locations. Here, we combine location-selective kinase inhibition, live-cell imaging and biochemical assays to probe the regulation of growth factor-induced mTORC1 activity in the nucleus. Using a nuclear targeted Akt Substrate-based Tandem Occupancy Peptide Sponge (Akt-STOPS) that we developed for specific inhibition of Akt, a critical upstream kinase, we show that growth factor-stimulated nuclear mTORC1 activity requires nuclear Akt activity. Further mechanistic dissection suggests that nuclear Akt activity mediates growth factor-induced nuclear translocation of Raptor, a regulatory scaffolding component in mTORC1, and localization of Raptor to the nucleus results in nuclear mTORC1 activity in the absence of growth factor stimulation. Taken together, these results reveal a mode of regulation of mTORC1 that is distinct from its lysosomal activation, which controls mTORC1 activity in the nuclear compartment.

High PRAS40 mRNA expression and its role in prognosis of clear cell renal cell carcinoma

Background

Clear cell renal cell carcinoma (ccRCC) is one of the most common type of kidney malignancy. The proline-rich Akt substrate of 40 kDa (PRAS40) plays an important role in tumor growth. The present study aimed to analysis the prognostic value of PRAS40 mRNA expression in ccRCC.

Methods

We analyzed the PRAS40 mRNA expression using the data from TCGA-KIRC cohort. A receiver operating characteristic (ROC) curve was performed to assessed the diagnostic value of PRAS40 mRNA expression in ccRCC. Chi-square test was used to analyzed the correlation between clinical characteristics and PRAS40 mRNA expression. Kaplan-Meier analysis and Cox analysis were performed to determine the prognostic value of PRAS40 mRNA expression in ccRCC. Gene set enrichment analysis (GSEA) was conducted using TCGA database.

Results

Our results revealed that PRAS40 mRNA expression was higher in ccRCC tissues than in normal tissues. PRAS40 presented a moderate diagnostic value in ccRCC. High PRAS40 mRNA expression was correlated with histological grade, clinical stage, T classification, distant metastasis and vital status of ccRCC. High PRAS40 mRNA expression was associated with poor overall survival. Furthermore, Multivariate analysis revealed that PRAS40 was an independent risk factor for ccRCC patients. Myc targets, DNA repair, oxidative phosphorylation, glycolysis, adipogenesis, p53 pathway, reactive oxygen species pathway, myogenesis were differentially enriched in the phenotype that positively correlated with PRAS40.

Conclusions

In conclusion, our results suggest that PRAS40 was a promising diagnostic and prognostic biomarker for ccRCC.

Quantitative proteomic and phosphoproteomic profiling of ischemic myocardial stunning in swine

Despite decades of research on the pathophysiology of myocardial stunning, protein changes and/or phosphorylation status underlying alterations in cardiac function/structure remain inadequately understood. Here, we utilized comprehensive and quantitative proteomic and phosphoproteomic approaches to explore molecular mechanisms of myocardial stunning in swine. The closed-chest swine (n = 5 pigs) were subjected to a 10-min left anterior descending coronary artery (LAD) occlusion producing regional myocardial stunning. Tissues from the ischemic LAD region and a remote nonischemic area of the left ventricle were collected 1 h after reperfusion. Ion current-based proteomics (IonStar) and quantitative phosphoproteomics were employed in parallel to identify alterations in protein level and site-specific phosphorylation changes. A novel swine heart protein database exhibiting high accuracy and low redundancy was developed here to facilitate comprehensive study. Further informatic investigations identified potential protein-protein interactions in stunned myocardium. In total, we quantified 2,099 protein groups and 4,699 phosphorylation sites with only 0.4% missing values. Proteomic analyses revealed downregulation of contractile function and extracellular matrix remodeling. Meanwhile, alterations in phosphorylation linked with contractile dysfunction and apoptotic cell death were uncovered. NetworKIN/STRING analysis predicted regulatory kinases responsible for altered phosphosites, such as protein kinase C-mediated phosphorylation of cardiac troponin I-S199 and CaMKII-mediated phosphorylation of phospholamban-T17. In summary, the ion current-based proteomics and phosphoproteomics reliably identified novel alterations in protein content and phosphorylation contributing to contractile dysfunction, extracellular matrix (ECM) damage, and programmed cell death in stunned myocardium, which corroborate well with our physiological observations. Moreover, this work developed a comprehensive database of the swine heart proteome, a highly valuable resource for future translational research in porcine models with cardiovascular diseases.NEW & NOTEWORTHY We first used ion current-based proteomics and phosphoproteomics to reliably identify novel alterations in protein expression and phosphorylation contributing to contractile dysfunction, extracellular matrix (ECM) damage, and programmed cell death in stunned myocardium and developed a comprehensive swine heart-specific proteome database, which provides a valuable resource for future research in porcine models of cardiovascular diseases.

The Multi-Modal Effect of the Anti-fibrotic Drug Pirfenidone on NSCLC

Although immune checkpoint and targeted therapies offer remarkable benefits for lung cancer treatment, some patients do not qualify for these regimens or do not exhibit consistent benefit. Provided that lung cancer appears to be driven by transforming growth factor beta signaling, we investigated the single drug potency of Pirfenidone, an approved drug for the treatment of lung fibrosis. Five human lung cancer cell lines and one murine line were investigated for transforming growth factor beta inhibition via Pirfenidone by using flow cytometry, In-Cell western analysis, proliferation assays as well as comprehensive analyses of the transcriptome with subsequent bioinformatics analysis. Overall, Pirfenidone induced cell cycle arrest, down-regulated SMAD expression and reduced proliferation in lung cancer. Furthermore, cell stress pathways and pro-apoptotic signaling may be mediated by reduced expression of Survivin. A murine subcutaneous model was used to assess the in vivo drug efficacy of Pirfenidone and showed reduced tumor growth and increased infiltration of T cells and NK cells. This data warrant further clinical evaluation of Pirfenidone with advanced non-small cell lung cancer. The observed in vitro and in vivo effects point to a substantial benefit for using Pirfenidone to reactivate the local immune response and possible application in conjunction with current immunotherapies.

PRAS40 hyperexpression promotes hepatocarcinogenesis

Background

Hepatocellular carcinoma (HCC) is one of the most common cancers, whereas the molecular mechanism remains largely unknown. PRAS40 (encoded by AKT1S1) phosphorylation was increased in human melanoma, prostate cancer and lung cancer specimens, which was considered as the results of Akt activation. However the mechanism in detail and its role in HCC stay elusive.

Methods

PRAS40 expression and phosphorylation were analyzed in HCC specimens, and the survival rates of patients were investigated. Functional analyses of PRAS40 in HCC were performed in vivo and in vitro. The miR-124-3p binding sites in PRAS40 were investigated using luciferase assay. MiR-124-3p expression in HCC specimens was examined by In Situ hybridization, and the correlation to PRAS40 level was evaluated.

Findings

The phosphorylation, protein and mRNA levels of PRAS40 were increased significantly in HCC specimens from our cohorts and TCGA database, which was positively correlated to the poor prognosis of HCC patients. Compared to Akt1s1^+/+ mice, hepatocarcinogenesis was suppressed in Akt1s1^−/− mice, and the activation of Akt was impaired. PRAS40 depletion resulted in the inhibition of HCC cellular proliferation. Tumor suppressor miR-124-3p was found to downregulate PRAS40 expression by targeting its 3′UTR. MiR-124-3p levels were inversely correlated to PRAS40 protein and phosphorylation levels in HCC specimens. The proliferation inhibition by miR-124-3p mimics was partially reversed by exogenous PRAS40 introduction in HCC cells.

Interpretation

PRAS40 hyperexpression induced by loss of miR-124-3p contributes to PRAS40 hyperphosphorylation and hepatocarcinogenesis. These results could be expected to offer novel clues for understanding hepatocarcinogenesis and developing approaches.

After Conventional Wisdom Has Failed, What Drives Wound Healing?

Between 2006 and 2015, the U.S. Food and Drug Administration’s (FDA) overall likelihood of approval (LOA) from Phase I clinical trials for all therapeutic candidates was 9.6%, with the highest LOA in haematology (26.1%) and the lowest in oncology (5.1%). Two critical features attributed to the success of advancing trials were i) targeting driver genes responsible for disease, and ii) use of human disease-relevant animal models during preclinical studies. For decades, conventional wisdom has been that growth factors are the drivers of wound healing, but few have either advanced to clinical applications or proven effective. The purpose of this paper is to explore heat shock protein 90-alpha (Hsp90α)’s role as a potential driver of wound healing and as a possible future therapeutic entity through a review of recent literature, including studies with human disease-relevant animal models. Of the approximately 7,000 gene products generated by a given mammalian cell type, the Hsp90 family of proteins (Hsp90α and Hsp90β) accounts for 2–3% of them. Hsp90β fulfils the role of an intracellular chaperone, but Hsp90α’s intracellular function is surprisingly dispensable. Instead, the abundancy of Hsp90α appears to have been prepared for extracellular purposes. When secreted via exosomes by cells under environmental stress, such as injury, Hsp90α protects cells from hypoxia-induced cell death, reduces local inflammation, and subsequently promotes cell migration to repair the injured tissue. Unlike conventional growth factors, secreted Hsp90α stimulates all major cell types involved in wound healing equally, resists microenvironmental inhibitors like TGFβ and hyperglycaemia, and is highly stable. Inhibition of exosome-mediated Hsp90α secretion, neutralisation of Hsp90α’s ATPase-independent extracellular functions, or interruption of Hsp90α-LRP-1 signalling blocks wound closure in vivo. Topical application of Hsp90α’s therapeutic entity, F-5 (a 115-amino acid peptide), has shown great promise for healing acute burn and diabetic wounds in mice and pigs.

Myeloid cell-derived LL-37 promotes lung cancer growth by activating Wnt/β-catenin signaling

Rationale: Antimicrobial peptides, such as cathelicidin LL-37/hCAP-18, are important effectors of the innate immune system with direct antibacterial activity. In addition, LL-37 is involved in the regulation of tumor cell growth. However, the molecular mechanisms underlying the functions of LL-37 in promoting lung cancer are not fully understood.

Methods: The expression of LL-37 in the tissues and sera of patients with non-small cell lung cancer was determined through immunohistological, immunofluorescence analysis, and enzyme-linked immunosorbent assay. The animal model of wild-type and Cramp knockout mice was employed to evaluate the tumorigenic effect of LL-37 in non-small cell lung cancer. The mechanism of LL-37 involving in the promotion of lung tumor growth was evaluated via microarray analyses, recombinant protein treatment approaches in vitro, tumor immunohistochemical assays, and intervention studies in vivo.

Results: LL-37 produced by myeloid cells was frequently upregulated in primary human lung cancer tissues. Moreover, its expression level correlated with poor clinical outcome. LL-37 activated Wnt/β-catenin signaling by inducing the phosphorylation of protein kinase B and subsequent phosphorylation of glycogen synthase kinase 3β mediated by the toll-like receptor-4 expressed in lung tumor cells. LL-37 treatment of tumor cells also decreased the levels of Axin2. In contrast, it elevated those of an RNA-binding protein (tristetraprolin), which may be involved in the mechanism through which LL-37 induces activation of Wnt/β-catenin.

Conclusion: LL-37 may be a critical molecular link between tumor-supportive immune cells and tumors, facilitating the progression of lung cancer.

Ribosomal Proteins Control Tumor Suppressor Pathways in Response to Nucleolar Stress

Ribosome biogenesis includes the making and processing of ribosomal RNAs, the biosynthesis of ribosomal proteins from their mRNAs in the cytosol and their transport to the nucleolus to assemble pre-ribosomal particles. Several stresses including cellular senescence reduce nucleolar rRNA synthesis and maturation increasing the availability of ribosome-free ribosomal proteins. Several ribosomal proteins can activate the p53 tumor suppressor pathway but cells without p53 can still arrest their proliferation in response to an imbalance between ribosomal proteins and mature rRNA production. Recent results on senescence-associated ribogenesis defects (SARD) show that the ribosomal protein S14 (RPS14 or uS11) can act as a CDK4/6 inhibitor linking ribosome biogenesis defects to the main engine of cell cycle progression. This work offers new insights into the regulation of the cell cycle and suggests novel avenues to design anticancer drugs.

Downregulation of CD147 induces malignant melanoma cell apoptosis via the regulation of IGFBP2 expression

Cluster of differentiation (CD)147, as a transmembrane glycoprotein, is highly expressed in a variety of tumors. Accumulating evidence has demonstrated that CD147 serves critical roles in tumor cell death and survival; however, the underlying mechanism requires further investigation. In the present study, it was revealed that CD147 knockdown significantly increased melanoma cell apoptosis. In addition, downregulation of CD147 reversed the malignant phenotype of melanoma, as demonstrated by the induction of tumor cell apoptosis in a xenograft mouse model. In addition, a human apoptosis antibody array was performed and 9 differentially expressed apoptosis-related proteins associated with CD147 were identified, including insulin-like growth factor-binding protein 2 (IGFBP2). Additionally, CD147 knockdown was observed to significantly decreased IGFBP2 expression at the mRNA and protein levels in melanoma cells. Providing that IGFBP2 is a downstream molecule in the phosphatase and tensin homolog (PTEN)/phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway, the effects of CD147 on this particular pathway were investigated. Interestingly, the expression of phosphorylated (p)-AKT and p‑mechanistic target of rapamycin was attenuated, whereas PTEN was markedly upregulated in CD147-underexpressing melanoma cells. Furthermore, application of a PI3K‑specific inhibitor also decreased IGFBP2 expression. Importantly, IGFBP2 was highly expressed in clinical tissues of melanoma compared with the control group, and its expression exhibited a positive association with CD147. The present study revealed that CD147 served a critical role in mediating the apoptosis of melanoma cells via IGFBP2 and the PTEN/PI3K/AKT signaling pathway. IGFBP2 and CD147 were observed to be overexpressed in clinical melanoma tissues; IGFBP2 was shown to be positively associated with CD147 expression, suggesting that CD147 may be considered as a potential therapeutic target for chemotherapy or prevention for in melanoma.

SPIN1 promotes tumorigenesis by blocking the uL18 (universal large ribosomal subunit protein 18)-MDM2-p53 pathway in human cancer

Ribosomal proteins (RPs) play important roles in modulating the MDM2-p53 pathway. However, less is known about the upstream regulators of the RPs. Here, we identify SPIN1 (Spindlin 1) as a novel binding partner of human RPL5/uL18 that is important for this pathway. SPIN1 ablation activates p53, suppresses cell growth, reduces clonogenic ability, and induces apoptosis of human cancer cells. Mechanistically, SPIN1 sequesters uL18 in the nucleolus, preventing it from interacting with MDM2, and thereby alleviating uL18-mediated inhibition of MDM2 ubiquitin ligase activity toward p53. SPIN1 deficiency increases ribosome-free uL18 and uL5 (human RPL11), which are required for SPIN1 depletion-induced p53 activation. Analysis of cancer genomic databases suggests that SPIN1 is highly expressed in several human cancers, and its overexpression is positively correlated with poor prognosis in cancer patients. Altogether, our findings reveal that the oncogenic property of SPIN1 may be attributed to its negative regulation of uL18, leading to p53 inactivation.

[Ribosomes synthesis at the heart of cell proliferation]

Ribosomes are central to gene expression. Their assembly is a complex and an energy consuming process. Many controls exist to make it possible a fine-tuning of ribosome production adapted to cell needs. In this review, we describe recent advances in the characterisation of the links occurring between ribosome synthesis and cell proliferation control. Defects in ribosome biogenesis directly impede cellular cycle and slow-down proliferation. Among the different factors involved, we could define the 5S particle, a ribosome sub-complex, as a key-regulator of p53 and other tumour suppressors such as pRB. This cross-talk between ribosome neogenesis defects and proliferation and cellular cycle also involves other cell cycle controls such as p14^ARF, SRSF1 or PRAS40 pathways. These data place ribosome synthesis at the heart of cell proliferation and offer new therapeutic strategies against cancer.

PRAS40 promotes NF-κB transcriptional activity through association with p65

PRAS40 has been shown to have a crucial role in the repression of mammalian target of rapamycin (mTOR). Nonetheless, PRAS40 appears to have an oncogenic function in cancer cells. Whether PRAS40 mediates signaling independent of mTOR inhibition in cancer cells remains elusive. Here PRAS40 overexpression in lung adenocarcinoma and cutaneous melanoma was significantly correlated to worse prognosis. And we identified an unexpected role for PRAS40 in the regulation of nuclear factor (NF)-κB signaling. P65, a subunit of the NF-κB transcription factor complex, was confirmed to associate with PRAS40 by glutathione S-transferase co-precipitation. Importantly, we found that PRAS40 can enhance NF-κB transcriptional activity in a manner dependent upon PRAS40–P65 association. Furthermore, we found that a small p65-derived peptide can disrupt the PRAS40–P65 association and significantly decrease NF-κB transcriptional activity. These findings may help elucidate the pleiotropic functions of PRAS40 in cells and suggest a novel therapeutic strategy in cancer patients with high expression of PRAS40 and NF-κB.

Identifying and analyzing different cancer subtypes using RNA-seq data of blood platelets

Detection and diagnosis of cancer are especially important for early prevention and effective treatments. Traditional methods of cancer detection are usually time-consuming and expensive. Liquid biopsy, a newly proposed noninvasive detection approach, can promote the accuracy and decrease the cost of detection according to a personalized expression profile. However, few studies have been performed to analyze this type of data, which can promote more effective methods for detection of different cancer subtypes. In this study, we applied some reliable machine learning algorithms to analyze data retrieved from patients who had one of six cancer subtypes (breast cancer, colorectal cancer, glioblastoma, hepatobiliary cancer, lung cancer and pancreatic cancer) as well as healthy persons. Quantitative gene expression profiles were used to encode each sample. Then, they were analyzed by the maximum relevance minimum redundancy method. Two feature lists were obtained in which genes were ranked rigorously. The incremental feature selection method was applied to the mRMR feature list to extract the optimal feature subset, which can be used in the support vector machine algorithm to determine the best performance for the detection of cancer subtypes and healthy controls. The ten-fold cross-validation for the constructed optimal classification model yielded an overall accuracy of 0.751. On the other hand, we extracted the top eighteen features (genes), including TTN, RHOH, RPS20, TRBC2, in another feature list, the MaxRel feature list, and performed a detailed analysis of them. The results indicated that these genes could be important biomarkers for discriminating different cancer subtypes and healthy controls.

PRAS40 Connects Microenvironmental Stress Signaling to Exosome-Mediated Secretion

Secreted exosomes carrying lipids, proteins, and nucleic acids conduct cell-cell communications within the microenvironment of both physiological and pathological conditions. Exosome secretion is triggered by extracellular or intracellular stress signals. Little is known, however, about the signal transduction between stress cues and exosome secretion. To identify the linker protein, we took advantage of a unique finding in human keratinocytes. In these cells, although transforming growth factor alpha (TGF-α) and epidermal growth factor (EGF) share the same EGF receptor and previously indistinguishable intracellular signaling networks, only TGF-α stimulation causes exosome-mediated secretion. However, deduction of EGF-activated pathways from TGFα-activated pathways in the same cells allowed us to identify the proline-rich Akt substrate of 40 kDa (PRAS40) as the unique downstream effector of TGF-α but not EGF signaling via threonine 308-phosphorylated Akt. PRAS40 knockdown (KD) or PRAS40 dominant-negative (DN) mutant overexpression blocks not only TGF-α- but also hypoxia- and H₂O₂-induced exosome secretion in a variety of normal and tumor cells. Site-directed mutagenesis and gene rescue studies show that Akt-mediated activation of PRAS40 via threonine 246 phosphorylation is both necessary and sufficient to cause exosome secretion without affecting the endoplasmic reticulum/Golgi pathway. Identification of PRAS40 as a linker protein paves the way for understanding how stress regulates exosome secretion under pathophysiological conditions.

Convergent Akt activation drives acquired EGFR inhibitor resistance in lung cancer

Non-small-cell lung cancer patients with activating epidermal growth factor receptor (EGFR) mutations typically benefit from EGFR tyrosine kinase inhibitor treatment. However, virtually all patients succumb to acquired EGFR tyrosine kinase inhibitor resistance that occurs via diverse mechanisms. The diversity and unpredictability of EGFR tyrosine kinase inhibitor resistance mechanisms presents a challenge for developing new treatments to overcome EGFR tyrosine kinase inhibitor resistance. Here, we show that Akt activation is a convergent feature of acquired EGFR tyrosine kinase inhibitor resistance, across a spectrum of diverse, established upstream resistance mechanisms. Combined treatment with an EGFR tyrosine kinase inhibitor and Akt inhibitor causes apoptosis and synergistic growth inhibition in multiple EGFR tyrosine kinase inhibitor-resistant non-small-cell lung cancer models. Moreover, phospho-Akt levels are increased in most clinical specimens obtained from EGFR-mutant non-small-cell lung cancer patients with acquired EGFR tyrosine kinase inhibitor resistance. Our findings provide a rationale for clinical trials testing Akt and EGFR inhibitor co-treatment in patients with elevated phospho-Akt levels to therapeutically combat the heterogeneity of EGFR tyrosine kinase inhibitor resistance mechanisms.

EGFR-mutant non-small cell lung cancer are often resistant to EGFR tyrosine kinase inhibitor treatment. In this study, the authors show that resistant tumors display high Akt activation and that a combined treatment with AKT inhibitors causes synergistic tumour growth inhibition in vitro and in vivo.

PRAS40 signaling in tumor

The proline-rich Akt substrate of 40 kDa (PRAS40) is a substrate of Akt and a component of the mammalian target of rapamycin complex 1 (mTORC1). Locating at the crossroad of the PI3K/Akt pathway and the mTOR pathway, PRAS40 is phosphorylated by growth factors or other stimuli, and regulates the activation of these signaling pathways in turn. PRAS40 plays an important role in metabolic disorders and multiple cancers, and the phosphorylation of PRAS40 is often associated with the tumor progression of melanoma, prostate cancer, etc. PRAS40 promotes tumorigenesis by deregulating cellular proliferation, apoptosis, senescence, metastasis, etc. Herein, we provide an overview on current understandings of PRAS40 signaling in the tumor formation and progression, which suggests that PRAS40 or phospho-PRAS40 could become a novel biomarker and therapeutic target in tumor.

miR-1908 Overexpression Inhibits Proliferation, Changing Akt Activity and p53 Expression in Hypoxic NSCLC Cells

The ribosomal protein (RP)-p53 pathway has been shown to play a key role in apoptosis and senescence of cancer cells. miR-1908 is a newly found miRNA that was reported to have prognostic potential in melanoma. However, its role and mechanism in the progression of non-small cell lung cancer (NSCLC) are largely unknown. In this study, we found that expression of miR-1908 was significantly downregulated in human NSCLC cell lines, including SK-MES-1, A549, and NCI-H460. Then the role of miR-1908 in NSCLC cell proliferation was explored. The miR-1908 mimic was transfected into NSCLC cell lines, and their proliferation was detected. MTT and Cell Titer-Blue H analyses showed that the cell proliferation was notably reduced by the miR-1908 mimic transfection. Moreover, we found the RP-p53 pathway was activated by miR-1908 mimic. Moreover, the miR-1908 inhibitor transfection had a completely opposite effect on the NSCLC cell proliferation than that of miR-1908 mimic. To explore the underlying mechanism of that, TargetScan bioinformatics server and 3'-UTR luciferase reporter assay were applied to identify the targets of miR-1908. Our results showed that AKT1 substrate 1 (AKT1S1), a newly proven suppressor of the RP-p53 pathway, was a target of miR-1908, suggesting a probable mechanism for miR-191 suppressing NSCLC cell proliferation. Our findings provide a novel molecular target for the regulation of NSCLC cell proliferation.

Targeting protein kinase-b3 (akt3) signaling in melanoma

INTRODUCTION

Deregulated Akt activity leading to apoptosis inhibition, enhanced proliferation and drug resistance has been shown to be responsible for 35-70% of advanced metastatic melanomas. Of the three isoforms, the majority of melanomas have elevated Akt3 expression and activity. Hence, potent inhibitors targeting Akt are urgently required, which is possible only if (a) the factors responsible for the failure of Akt inhibitors in clinical trials is known; and (b) the information pertaining to synergistically acting targeted therapeutics is available. Areas covered: This review provides a brief introduction of the PI3K-Akt signaling pathway and its role in melanoma development. In addition, the functional role of key Akt pathway members such as PRAS40, GSK3 kinases, WEE1 kinase in melanoma development are discussed together with strategies to modulate these targets. Efficacy and safety of Akt inhibitors is also discussed. Finally, the mechanism(s) through which Akt leads to drug resistance is discussed in this expert opinion review. Expert opinion: Even though Akt play key roles in melanoma tumor progression, cell survival and drug resistance, many gaps still exist that require further understanding of Akt functions, especially in the (a) metastatic spread; (b) circulating melanoma cells survival; and

AKT1, LKB1, and YAP1 Revealed as MYC Interactors with NanoLuc-Based Protein-Fragment Complementation Assay

The c-Myc (MYC) transcription factor is a major cancer driver and a well-validated therapeutic target. However, directly targeting MYC has been challenging. Thus, identifying proteins that interact with and regulate MYC may provide alternative strategies to inhibit its oncogenic activity. In this study, we report the development of a NanoLuc-based protein-fragment complementation assay (NanoPCA) and mapping of the MYC protein interaction hub in live mammalian cells. The NanoPCA system was configured to enable detection of protein-protein interactions (PPI) at the endogenous level, as shown with PRAS40 dimerization, and detection of weak interactions, such as PINCH1-NCK2. Importantly, NanoPCA allows the study of PPI dynamics with reversible interactions. To demonstrate its utility for large-scale PPI detection in mammalian intracellular environment, we have used NanoPCA to examine MYC interaction with 83 cancer-associated proteins in live cancer cell lines. Our new MYC PPI data confirmed known MYC-interacting proteins, such as MAX, GSK3A, and SMARCA4, and revealed a panel of novel MYC interaction partners, such as RAC-α serine/threonine-protein kinase (AKT)1, liver kinase B (LKB)1, and Yes-associated protein (YAP)1. The MYC interactions with AKT1, LKB1, and YAP1 were confirmed by coimmunoprecipitation of endogenous proteins. Importantly, AKT1, LKB1, and YAP1 were able to activate MYC in a transcriptional reporter assay. Thus, these vital growth control proteins may represent promising MYC regulators, suggesting new mechanisms that couple energetic and metabolic pathways and developmental signaling to MYC-regulated cellular programs.

Benzyl Isothiocyanate potentiates p53 signaling and antitumor effects against breast cancer through activation of p53-LKB1 and p73-LKB1 axes

Functional reactivation of p53 pathway, although arduous, can potentially provide a broad-based strategy for cancer therapy owing to frequent p53 inactivation in human cancer. Using a phosphoprotein-screening array, we found that Benzyl Isothiocynate, (BITC) increases p53 phosphorylation in breast cancer cells and reveal an important role of ERK and PRAS40/MDM2 in BITC-mediated p53 activation. We show that BITC rescues and activates p53-signaling network and inhibits growth of p53-mutant cells. Mechanistically, BITC induces p73 expression in p53-mutant cells, disrupts the interaction of p73 and mutant-p53, thereby releasing p73 from sequestration and allowing it to be transcriptionally active. Furthermore, BITC-induced p53 and p73 axes converge on tumor-suppressor LKB1 which is transcriptionally upregulated by p53 and p73 in p53-wild-type and p53-mutant cells respectively; and in a feed-forward mechanism, LKB1 tethers with p53 and p73 to get recruited to p53-responsive promoters. Analyses of BITC-treated xenografts using LKB1-null cells corroborate in vitro mechanistic findings and establish LKB1 as the key node whereby BITC potentiates as well as rescues p53-pathway in p53-wild-type as well as p53-mutant cells. These data provide first in vitro and in vivo evidence of the integral role of previously unrecognized crosstalk between BITC, p53/LKB1 and p73/LKB1 axes in breast tumor growth-inhibition.

Nucleolus-derived mediators in oncogenic stress response and activation of p53-dependent pathways

Rapid growth and division of cells, including tumor ones, is correlated with intensive protein biosynthesis. The output of nucleoli, organelles where translational machineries are formed, depends on a rate of particular stages of ribosome production and on accessibility of elements crucial for their effective functioning, including substrates, enzymes as well as energy resources. Different factors that induce cellular stress also often lead to nucleolar dysfunction which results in ribosome biogenesis impairment. Such nucleolar disorders, called nucleolar or ribosomal stress, usually affect cellular functioning which in fact is a result of p53-dependent pathway activation, elicited as a response to stress. These pathways direct cells to new destinations such as cell cycle arrest, damage repair, differentiation, autophagy, programmed cell death or aging. In the case of impaired nucleolar functioning, nucleolar and ribosomal proteins mediate activation of the p53 pathways. They are also triggered as a response to oncogenic factor overexpression to protect tissues and organs against extensive proliferation of abnormal cells. Intentional impairment of any step of ribosome biosynthesis which would direct the cells to these destinations could be a strategy used in anticancer therapy. This review presents current knowledge on a nucleolus, mainly in relation to cancer biology, which is an important and extremely sensitive element of the mechanism participating in cellular stress reaction mediating activation of the p53 pathways in order to counteract stress effects, especially cancer development.

Targeting PRAS40 for multiple diseases

Proline-rich Akt substrate 40kDa (PRAS40) bridges cell signaling between protein kinase B (Akt) and the mammalian target of rapamycin complex 1 (mTORC1). Both Akt and mTORC1 can phosphorylate PRAS40. As a negative regulator of mTORC1, PRAS40 prevents the binding of mTOR to its substrates. The phosphorylation of PRAS40 results in its dissociation from mTORC1 and enhanced mTOR activation. PRAS40 in conjunction with mTORC1 has been closely associated with programmed cell death and is implicated in diabetes mellitus (DM), cardiovascular diseases, cancer, and neurological diseases. Thus, targeting PRAS40 might hold great promise for innovative therapeutic strategies for these diseases.

PRAS40 deregulates apoptosis in Ewing sarcoma family tumors by enhancing the insulin receptor/Akt and mTOR signaling pathways

EWS expression in Ewing sarcoma family tumors (ESFTs) is decreased due to the haploinsufficiency elicited by chromosomal translocation. The abnormal expression levels of EWS and its downstream factors contribute to the manifestation of ESFTs. Previously, we reported that increased Proline-rich Akt substrate of 40 kDa (PRAS40), which is encoded by an EWS mRNA target, promotes the development of ESFTs. However, the mechanism remains elusive. To clarify the role of PRAS40 in ESFTs, we silenced PRAS40 expression in ESFT cells using siRNAs and found increased levels of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells. Cleaved caspase 3 levels and cytochrome C release were increased simultaneously. Furthermore, with PRAS40 knockdown, the phosphorylation of Akt and mTOR downstream factors, i.e., S6K and S6, was attenuated notably. Ectopic expression of PRAS40 increased Akt and S6 phosphorylation. Activation of Akt only partially reversed the apoptosis induced by PRAS40 knockdown, and downregulation of S6 phosphorylation by PRAS40 silencing could not be sufficiently restored via Akt activation. Searching the upstream factors in this pathway, the autophosphorylation of insulin receptor (IR) was found to be inhibited significantly by PRAS40 silencing but increased by PRAS40 overexpression. Therefore, PRAS40 may enhance IR phosphorylation to facilitate Akt and mTOR signaling leading to the apoptosis deregulation in ESFTs. Moreover, in vivo results confirmed that PRAS40 deletion suppressed the growth of ESFT xenografts and downregulated IR and S6 phosphorylation. Our findings suggest a novel functioning model for PRAS40, which represents a novel therapeutic target for ESFTs.

Enabling systematic interrogation of protein-protein interactions in live cells with a versatile ultra-high-throughput biosensor platform

Large-scale genomics studies have generated vast resources for in-depth understanding of vital biological and pathological processes. A rising challenge is to leverage such enormous information to rapidly decipher the intricate protein-protein interactions (PPIs) for functional characterization and therapeutic interventions. While a number of powerful technologies have been employed to detect PPIs, a singular PPI biosensor platform with both high sensitivity and robustness in a mammalian cell environment remains to be established. Here we describe the development and integration of a highly sensitive NanoLuc luciferase-based bioluminescence resonance energy transfer technology, termed BRET(n), which enables ultra-high-throughput (uHTS) PPI detection in live cells with streamlined co-expression of biosensors in a miniaturized format. We further demonstrate the application of BRET(n) in uHTS format in chemical biology research, including the discovery of chemical probes that disrupt PRAS40 dimerization and pathway connectivity profiling among core members of the Hippo signaling pathway. Such hippo pathway profiling not only confirmed previously reported PPIs, but also revealed two novel interactions, suggesting new mechanisms for regulation of Hippo signaling. Our BRET(n) biosensor platform with uHTS capability is expected to accelerate systematic PPI network mapping and PPI modulator-based drug discovery.

Modulation of Breast Cancer Risk Biomarkers by High-Dose Omega-3 Fatty Acids: Phase II Pilot Study in Premenopausal Women

Higher intakes of the omega-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) relative to the omega-6 arachidonic acid (AA) have been variably associated with reduced risk of premenopausal breast cancer. The purpose of this pilot trial was to assess feasibility and explore the effects of high-dose EPA and DHA on blood and benign breast tissue risk biomarkers before design of a placebo-controlled phase IIB trial. Premenopausal women with evidence of hyperplasia ± atypia by baseline random periareolar fine needle aspiration were given 1860 mg of EPA + 1500 mg of DHA ethyl esters daily for 6 months. Blood and benign breast tissue were sampled during the same menstrual cycle phase prestudy and a median of 3 weeks after last dose. Additional blood was obtained within 24 hours of last dose. Feasibility, which was predefined as 50% uptake, 85% retention, and 70% compliance, was demonstrated with 46% uptake, 94% completion, and 85% compliance. Cytologic atypia decreased from 77% to 38% (P = 0.002), and Ki-67 from a median of 2.1% to 1.0% (P = 0.021) with an increase in the ratio of EPA + DHA to AA in erythrocyte phospholipids but no change in blood hormones, adipokines, or cytokines. Exploratory breast proteomics assessment showed decreases in several proteins involved in hormone and cytokine signaling with mixed effects on those in the AKT/mTOR pathways. Further investigation of EPA plus DHA for breast cancer prevention in a placebo-controlled trial in premenopausal women is warranted.

Modulation of Breast Cancer Risk Biomarkers by High-Dose Omega-3 Fatty Acids: Phase II Pilot Study in Postmenopausal Women

Associational studies suggest higher intakes/blood levels of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) relative to the omega-6 arachidonic acid (AA) are associated with reduced breast cancer risk. We performed a pilot study of high-dose EPA + DHA in postmenopausal women to assess feasibility before initiating a phase IIB prevention trial. Postmenopausal women with cytologic evidence of hyperplasia in their baseline random periareolar fine needle aspiration (RPFNA) took 1,860 mg EPA +1500 mg DHA ethyl esters daily for 6 months. Blood and breast tissue were sampled at baseline and study conclusion for exploratory biomarker assessment, with P values uncorrected for multiple comparisons. Feasibility was predefined as 50% uptake, 80% completion, and 70% compliance. Trial uptake by 35 study entrants from 54 eligible women was 65%, with 97% completion and 97% compliance. Favorable modulation was suggested for serum adiponectin (P = 0.0027), TNFα (P = 0.016), HOMA 2B measure of pancreatic β cell function (P = 0.0048), and bioavailable estradiol (P = 0.039). Benign breast tissue Ki-67 (P = 0.036), macrophage chemoattractant protein-1 (P = 0.033), cytomorphology index score (P = 0.014), and percent mammographic density (P = 0.036) were decreased with favorable effects in a proteomics array for several proteins associated with mitogen signaling and cell-cycle arrest; but no obvious overall effect on proteins downstream of mTOR. Although favorable risk biomarker modulation will need to be confirmed in a placebo-controlled trial, we have demonstrated feasibility for development of high-dose EPA and DHA ethyl esters for primary prevention of breast cancer.