Targeting RPL39 and MLF2 reduces tumor initiation and metastasis in breast cancer by inhibiting nitric oxide synthase signaling. Proc Natl Acad Sci U S A. 2014;111:8838-8843. [PMID: 24876273 DOI: 10.1073/pnas.1320769111]

CDK2-mediated site-specific phosphorylation of EZH2 drives and maintains triple-negative breast cancer

Triple-negative breast cancer (TNBC), which lacks estrogen receptor α (ERα), progesterone receptor, and human epidermal growth factor receptor 2 (HER2) expression, is closely related to basal-like breast cancer. Previously, we and others report that cyclin E/cyclin-dependent kinase 2 (CDK2) phosphorylates enhancer of zeste homolog 2 (EZH2) at T416 (pT416-EZH2). Here, we show that transgenic expression of phospho-mimicking EZH2 mutant EZH2^T416D in mammary glands leads to tumors with TNBC phenotype. Coexpression of EZH2^T416D in mammary epithelia of HER2/Neu transgenic mice reprograms HER2-driven luminal tumors into basal-like tumors. Pharmacological inhibition of CDK2 or EZH2 allows re-expression of ERα and converts TNBC to luminal ERα-positive, rendering TNBC cells targetable by tamoxifen. Furthermore, the combination of either CDK2 or EZH2 inhibitor with tamoxifen effectively suppresses tumor growth and markedly improves the survival of the mice bearing TNBC tumors, suggesting that the mechanism-based combination therapy may be an alternative approach to treat TNBC.

EZH2 phosphorylation by CDK2 promotes progression of triple-negative breast cancer (TNBC). Here, the authors show that this signaling axis downregulates ERα, and thus combinatorial blockade of CDK2 and EZH2 sensitizes TNBC cells to tamoxifen.

Detection of breast cancer stem cell gene mutations in circulating free DNA during the evolution of metastases

PURPOSE

Limited knowledge exists on the detection of breast cancer stem cell (BCSC)-related mutations in circulating free DNA (cfDNA) from patients with advanced cancers. Identification of new cancer biomarkers may allow for earlier detection of disease progression and treatment strategy modifications.

METHODS

We conducted a prospective study to determine the feasibility and prognostic utility of droplet digital polymerase chain reaction (ddPCR)-based BCSC gene mutation analysis of cfDNA in patients with breast cancer.

RESULTS

Detection of quantitative BCSC gene mutation in cfDNA by ddPCR mirrors disease progression and thus may represent a valuable and cost-effective measure of tumor burden. We have previously shown that hematological and neurological expressed 1-like (HN1L), ribosomal protein L39 (RPL39), and myeloid leukemia factor 2 (MLF2) are novel targets for BCSC self-renewal, and targeting these genetic alterations could be useful for personalized genomic-based therapy.

CONCLUSION

BCSC mutation detection in cfDNA may have important implications for diagnosis, prognosis, and serial monitoring.

Tracking Biodistribution of Myeloid-Derived Cells in Murine Models of Breast Cancer

A growing tumor is constantly secreting inflammatory chemokines and cytokines that induce release of immature myeloid cells, including myeloid-derived suppressor cells (MDSCs) and macrophages, from the bone marrow. These cells not only promote tumor growth, but also prepare distant organs for tumor metastasis. On the other hand, the myeloid-derived cells also have phagocytic potential, and can serve as vehicles for drug delivery. We have previously identified thioaptamers that bind a subset of MDSCs with high affinity and specificity. In the current study, we applied one of the thioaptamers as a probe to track myeloid cell distribution in the bone, liver, spleen and tumor in multiple murine models of breast cancer including the 4T1 syngeneic model and MDA-MB-231 and SUM159 xenograft models. Information generated from this study will facilitate further understanding of tumor growth and metastasis, and predict biodistribution patterns of cell-mediated drug delivery.

Current Challenges in Cancer Immunotherapy: Multimodal Approaches to Improve Efficacy and Patient Response Rates

Cancer immunotherapy is a promising innovative treatment for many forms of cancer, particularly melanoma. Although immunotherapy has been shown to be efficacious, patient response rates vary and, more often than not, only a small subset of the patients within a large cohort respond favourably to the treatment. This issue is particularly concerning and becomes a challenge of immunotherapy to improve the effectiveness and patient response rates. Here, we review the specific types of available immunotherapy options, their proposed mechanism(s) of action, and the reasons why the patient response to this treatment is variable. The potential favourable options to improve response rates to immunotherapy will be discussed with an emphasis on adopting a multimodal approach on the novel role that the gut microbiota may play in modulating the efficacy of cancer immunotherapy.

Cancer therapeutic targeting using mutant-p53-specific siRNAs

Mutations in Tp53 compromise therapeutic response, due either to the dominant-negative effect over the functional wild-type allele; or as a result of the survival advantage conferred by mutant p53 to which cancer cells become addicted. Thus, targeting mutant p53 represents an effective therapeutic strategy to treat over half of all cancers. We have therefore generated a series of small-interfering-RNAs, capable of targeting four p53 hot-spot mutants which represent ~20% of all p53 mutations. These mutant–p53-specific siRNAs (MupSi) are highly specific in silencing the expression of the intended mutants without affecting wild-type p53. Functionally, these MupSis induce cell death by abrogating both the addiction to mutant p53 and the dominant-negative effect; and retard tumor growth in xenografts when administered in a therapeutic setting. These data together demonstrate the possibility of targeting mutant p53 specifically to improve clinical outcome.

Ribosomal protein S27-like regulates autophagy via the β-TrCP-DEPTOR-mTORC1 axis

RPS27L (Ribosomal protein S27-like), an evolutionarily conserved ribosomal protein, is a p53 target and a physiological p53 regulator. We previously reported that Rps27l disruption enhanced lymphomagenesis in Trp53^+/− mice by triggering genome instability and sensitized Trp53^+/− mice to radiation by blocking DNA damage response. Whether and how RPS27L modulates autophagy is totally unknown. Here we report that RPS27L silencing significantly induced autophagy in breast cancer MB231 and SK-BR3 cells harboring mutant p53. Mechanistically, RPS27L silencing remarkably inactivated mTORC1, a major negative autophagy regulator, but not mTORC2. Autophagy induction and mTORC1 inactivation was also observed in MEFs with Rps27l deletion. More specifically, RPS27L silencing shortened the protein half-life of β-TrCP, a substrate receptor of Skp1-Cullin 1-F-box (SCF) ubiquitin ligase, which is responsible for DEPTOR degradation, leading to DEPTOR accumulation to inhibit mTORC1 activity. Furthermore, RPS27L silencing-induced autophagy and mTORC1 inactivation can be partially rescued by simultaneous DEPTOR silencing, suggesting a causal role of DEPTOR. Biologically, autophagy inhibitor, chloroquine (CQ), or Bafilomycin A1 (BAF A1), significantly induced apoptosis in RPS27L silenced cells, indicating that autophagy is a cellular survival mechanism in response to RPS27L loss. Finally, RPS27L levels were reduced in human breast cancers, as compared to adjacent normal tissues. Collectively, our study suggests that RPS27L reduction might play a promoting role during breast tumorigenesis by autophagy induction via the β-TrCP-DEPTOR-mTORC1 axis.

ChIP-seq analysis reveals alteration of H3K4 trimethylation occupancy in cancer-related genes by cold atmospheric plasma

Cold atmospheric plasma (CAP) has gained attention for use in cancer treatment owing to its ability to preferentially induce cancer cell death; however, the involved molecular mechanism remains to be elucidated. Herein, an epigenetic effect of CAP on cancer cells was examined by performing a genome-wide ChIP-seq for H3K4me3 in MCF-7 breast cancer cell line. Consequently, 899 genes showed significantly changed methylation level at H3K4 with constructing "Cellular Compromise, DNA Replication, Recombination, Repair, and Cell Cycle" as the top network. Comparisons with expression array data revealed a coincidence between histone modification and gene expression for 18 genes, and the association was confirmed by ChIP-PCR and qRT-PCR for selected genes. The expression of the affected genes, such as HSCB and PRPS1, was recovered when a histone demethylase JARID1A was inhibited. Furthermore, JARID1A was induced by CAP via the reactive oxygen species signaling. The two genes are known as oncogenes and show a higher expression in breast cancer tissue, and this was supported by the decreased colony formation ability of MCF-7 cells when the cells were treated with siRNAs against each gene. Taken together, these data indicate that CAP inhibits cancer cell proliferation by modulating the methylation level of H3K4 corresponding to oncogenes.

Surfactant and Chaotropic Agent Assisted Sequential Extraction/On-Pellet Digestion (SCAD) for Enhanced Proteomics

As a popular sample preparation approach, filter-aided sample preparation (FASP) has been widely used in proteomic analysis. However, several limitations have been noted, including sample loss during filtration, repetitive centrifugation steps, and the possibility of breakage of filtration membrane. Extraction bias among different sample preparation strategies presents another challenge. To overcome these limitations and address remaining challenges, we developed a novel surfactant and chaotropic agent assisted sequential extraction/on-pellet digestion (SCAD) protocol. The new strategy resulted in higher protein yield and improved peptide recovery and protein coverage compared to two conventional sample preparation methods (FASP and urea). In combination of three strategies, more than 10,000 distinct protein groups were identified with 1% FDR from MDA-MB-231 cells without any prefractionation. This in-depth proteome analysis was accomplished by optimization of protein extraction, enzymatic digestion, LC gradient, and peptide sequencing method. Ingenuity Pathways Analysis (IPA) of proteins exclusively identified in SCAD revealed several crucial signaling pathways that regulate breast cancer progression. SCAD also enabled an unbiased extraction of different categories of proteins (membrane, intracellular, nuclear) associated with tumorigenesis, which integrates the advantages of FASP and urea extraction. This novel strategy expedites comprehensive protein identification, which is applicable for biomarker discovery in various types of cancers.

Activating Transcription Factor 4 Modulates TGFβ-Induced Aggressiveness in Triple-Negative Breast Cancer via SMAD2/3/4 and mTORC2 Signaling

Purpose: On the basis of the identified stress-independent cellular functions of activating transcription factor 4 (ATF4), we reported enhanced ATF4 levels in MCF10A cells treated with TGFβ1. ATF4 is overexpressed in patients with triple-negative breast cancer (TNBC), but its impact on patient survival and the underlying mechanisms remain unknown. We aimed to determine ATF4 effects on patients with breast cancer survival and TNBC aggressiveness, and the relationships between TGFβ and ATF4. Defining the signaling pathways may help us identify a cell signaling-tailored gene signature.Experimental Design: Patient survival data were determined by Kaplan-Meier analysis. Relationship between TGFβ and ATF4, their effects on aggressiveness (tumor proliferation, metastasis, and stemness), and the underlying pathways were analyzed in three TNBC cell lines and in vivo using patient-derived xenografts (PDX).Results: ATF4 overexpression correlated with TNBC patient survival decrease and a SMAD-dependent crosstalk between ATF4 and TGFβ was identified. ATF4 expression inhibition reduced migration, invasiveness, mammosphere-forming efficiency, proliferation, epithelial-mesenchymal transition, and antiapoptotic and stemness marker levels. In PDX models, ATF4 silencing decreased metastases, tumor growth, and relapse after chemotherapy. ATF4 was shown to be active downstream of SMAD2/3/4 and mTORC2, regulating TGFβ/SMAD and mTOR/RAC1-RHOA pathways independently of stress. We defined an eight-gene signature with prognostic potential, altered in 45% of 2,509 patients with breast cancer.Conclusions: ATF4 may represent a valuable prognostic biomarker and therapeutic target in patients with TNBC, and we identified a cell signaling pathway-based gene signature that may contribute to the development of combinatorial targeted therapies for breast cancer. Clin Cancer Res; 24(22); 5697-709. ©2018 AACR.

Chemotherapy Sensitizes Therapy-Resistant Cells to Mild Hyperthermia by Suppressing Heat Shock Protein 27 Expression in Triple-Negative Breast Cancer

Purpose: Triple-negative breast cancer (TNBC) is a clinically aggressive disease with poor prognosis. Conventional chemotherapeutics are generally able to shrink the tumor mass, but often fail to completely eradicate cancer stem-like cells (CSCs) that are responsible for high risk of relapse and frequent metastases. In this study, we examined thermal sensibility of CSCs, developed an approach that enabled concurrent elimination of both the bulk of cancer cells and CSCs, and investigated the underlying mechanism.Experimental Design: We designed a platform consisting of gold nanoparticle-coated porous silicon microparticle (AuPSM) that was also loaded with docetaxel micelles (mDTXs) to enable concurrent killing of the bulk of cancer cells by released mDTX and CSCs by mild hyperthermia upon stimulation of AuPSM with near infrared. In addition, we examined the role of heat shock proteins in sensitizing CSC killing. Finally, we applied mDTX-loaded AuPSM to treat mice with SUM159 and 4T1 orthotopic tumors and evaluated tumor growth and tumor metastasis.Results: MDA-MB-231 and SUM159 TNBC cells treated with mDTX-loaded AuPSM and mild hyperthermia displayed significantly reduced efficiencies in mammosphere formation than those treated with mDTX alone or mild hyperthermia alone. Combination treatment also completely inhibited SUM159 orthotopic tumor growth and 4T1 tumor metastasis. Mechanistically, DTX treatment suppressed expression of heat shock protein 27 in cancer cells including the CSCs, rendering cells sensitive to mild hyperthermia.Conclusions: Our results indicate that chemotherapy sensitizes CSC to mild hyperthermia. We have developed an effective therapeutic approach to eliminate therapy-resistant cells in TNBC. Clin Cancer Res; 24(19); 4900-12. ©2018 AACR.

The ribosome, (slow) beating heart of cancer (stem) cell

The ribosome has long been considered as a consistent molecular factory, with a rather passive role in the translation process. Recent findings have shifted this obsolete view, revealing a remarkably complex and multifaceted machinery whose role is to orchestrate spatiotemporal control of gene expression. Ribosome specialization discovery has raised the interesting possibility of the existence of its malignant counterpart, an 'oncogenic' ribosome, which may promote tumor progression. Here we weigh the arguments supporting the existence of an 'oncogenic' ribosome and evaluate its role in cancer evolution. In particular, we provide an analysis and perspective on how the ribosome may play a critical role in the acquisition and maintenance of cancer stem cell phenotype.

Transient external force induces phenotypic reversion of malignant epithelial structures via nitric oxide signaling

Non-malignant breast epithelial cells cultured in three-dimensional laminin-rich extracellular matrix (lrECM) form well organized, growth-arrested acini, whereas malignant cells form continuously growing disorganized structures. While the mechanical properties of the microenvironment have been shown to contribute to formation of tissue-specific architecture, how transient external force influences this behavior remains largely unexplored. Here, we show that brief transient compression applied to single malignant breast cells in lrECM stimulated them to form acinar-like structures, a phenomenon we term 'mechanical reversion.' This is analogous to previously described phenotypic 'reversion' using biochemical inhibitors of oncogenic pathways. Compression stimulated nitric oxide production by malignant cells. Inhibition of nitric oxide production blocked mechanical reversion. Compression also restored coherent rotation in malignant cells, a behavior that is essential for acinus formation. We propose that external forces applied to single malignant cells restore cell-lrECM engagement and signaling lost in malignancy, allowing them to reestablish normal-like tissue architecture.

Pharmacological Inhibition of NOS Activates ASK1/JNK Pathway Augmenting Docetaxel-Mediated Apoptosis in Triple-Negative Breast Cancer

Purpose: Chemoresistance in triple-negative breast cancer (TNBC) is associated with the activation of a survival mechanism orchestrated by the endoplasmic reticulum (EnR) stress response and by inducible nitric oxide synthase (iNOS). Our aim was to determine the effects of pharmacologic NOS inhibition on TNBC.Experimental Design: TNBC cell lines, SUM-159PT, MDA-MB-436, and MDA-MB-468, were treated with docetaxel and NOS inhibitor (L-NMMA) for 24, 48, and 72 hours. Apoptosis was assessed by flow cytometry using Annexin-V and propidium iodide. Western blot was used to assess ER stress and apoptosis, and rtPCR was used to evaluate s-XBP1. TNBC patient-derived xenografts (PDX) were treated either with vehicle, docetaxel, or combination therapy (NOS inhibition + docetaxel). Mouse weight and tumor volumes were recorded twice weekly. Docetaxel concentration was determined using mass spectrometry. To quantify proliferation and apoptosis, PDX tumor samples were stained using Ki67 and TUNEL assay.Results:In vitro, L-NMMA ameliorated the iNOS upregulation associated with docetaxel. Apoptosis increased when TNBC cells were treated with combination therapy. In TNBC PDXs, combination therapy significantly reduced tumor volume growth and increased survival proportions. In the BCM-5998 PDX model, intratumoral docetaxel concentration was higher in mice receiving combination therapy. Coupling docetaxel with NOS inhibition increased EnR-stress response via coactivation of ATF4 and CHOP, which triggered the pASK1/JNK proapoptotic pathway, promoting cleavage of caspases 3 and 9.Conclusions: iNOS is a critical target for docetaxel resistance in TNBC. Pharmacologic inhibition of NOS enhanced chemotherapy response in TNBC PDX models. Combination therapy may improve prognosis and prevent relapse in TNBC patients who have failed conventional chemotherapy. Clin Cancer Res; 24(5); 1152-62. ©2018 AACR.

HN1L Promotes Triple-Negative Breast Cancer Stem Cells through LEPR-STAT3 Pathway

Here, we show that HEMATOLOGICAL AND NEUROLOGICAL EXPRESSED 1-LIKE (HN1L) is a targetable breast cancer stem cell (BCSC) gene that is altered in 25% of whole breast cancer and significantly correlated with shorter overall or relapse-free survival in triple-negative breast cancer (TNBC) patients. HN1L silencing reduced the population of BCSCs, inhibited tumor initiation, resensitized chemoresistant tumors to docetaxel, and hindered cancer progression in multiple TNBC cell line-derived xenografts. Additionally, gene signatures associated with HN1L correlated with shorter disease-free survival of TNBC patients. We defined HN1L as a BCSC transcription regulator for genes involved in the LEPR-STAT3 signaling axis as HN1L binds to a putative consensus upstream sequence of STAT3, LEPTIN RECEPTOR, and MIR-150. Our data reveal that BCSCs in TNBC depend on the transcription regulator HN1L for the sustained activation of the LEPR-STAT3 pathway, which makes it a potentially important target for both prognosis and BCSC therapy.

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HN1L expression is correlated with shorter survival of TNBC patients

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HN1L regulates BCSCs by promoting the STAT3 signaling pathway

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HN1L: novel transcription regulator of LEPR and miR-150, upstream regulators of STAT3

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HN1L-regulated gene signatures can predict clinical outcomes in TNBC patients

Evaluation of Prognosis in Hormone Receptor-Positive/HER2-Negative and Lymph Node-Negative Breast Cancer With Low Oncotype DX Recurrence Score

INTRODUCTION

Hormone receptor-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancers without lymph node metastasis have good prognosis. We compared the prognosis of hormone receptor-positive, HER2-negative, lymph node-negative cancers with Oncotype DX score ranges of 1 to 10 (1-10 group) and 11 to < 18 (11-18 group).

PATIENTS AND METHODS

A total of 107 cases in the 1-10 group and 225 cases in the 11-18 group were reviewed. All patients received surgery. The use of chemotherapy, radiotherapy, and endocrine therapy, and overall survival (OS), disease-free survival (DFS), and distant metastasis were compared between groups.

RESULTS

There were no statistical differences in the use of chemotherapy (5.05% vs. 6.05%, P = .724) or radiotherapy (52.53% vs. 59.07%, P = .276) between the 1-10 group and the 11-18 group, respectively. The median OS and DFS were 47 and 45 months, respectively, in the 1-10 group, and 49 and 48 months in the 11-18 group. No significant difference was seen in OS (P = .995), DFS (P = .148), or rates of metastasis (P = .998). The 11-18 group had more death events and distant metastasis (death, 5 events; recurrence, 2 events; metastasis, 2 events) than the 1-10 group (death, 0 events; recurrence, 4 events; metastasis, 0 events). The majority of recurrences seen in both groups were in young patients who failed to comply with their endocrine therapy regimen.

CONCLUSION

Patients in both the 1-10 group and the 11-18 group had good prognoses. Those who experienced recurrence were more likely to be premenopausal and to have failed to comply with the recommended endocrine therapy regimen. Endocrine therapy remains important in these patients.

Acquired ribosomopathies in leukemia and solid tumors

A mutation in the gene encoding the small subunit-associated ribosomal protein RPS19, leading to RPS19 haploinsufficiency, is one of the ribosomal protein gene defects responsible for the rare inherited bone marrow failure syndrome Diamond Blackfan anemia (DBA). Additional inherited and acquired defects in ribosomal proteins (RPs) continue to be identified and are the basis for a new class of diseases called the ribosomopathies. Acquired RPS14 haploinsufficiency has been found to be causative of the bone marrow failure found in 5q- myelodysplastic syndromes. Both under- and overexpression of RPs have also been implicated in several malignancies. This review will describe the somatic ribosomopathies that have been found to be associated with a variety of solid tumors as well as leukemia and will review cancers in which over- or underexpression of these proteins seem to be associated with outcome.

Enhancing cancer immunotherapy through nanotechnology-mediated tumor infiltration and activation of immune cells

Cancer immunotherapy has become arguably the most promising advancement in cancer research and therapy in recent years. The efficacy of cancer immunotherapy is critically dependent on specific physiological and physical processes - collectively referred to as transport barriers - including the activation of T cells by antigen presenting cells, T cells migration to and penetration into the tumor microenvironment, and movement of nutrients and other immune cells through the tumor microenvironment. Nanotechnology-based approaches have great potential to help overcome these transport barriers. In this review, we discuss the ways that nanotechnology is being leveraged to improve the efficacy and potency of various cancer immunotherapies.

Proteomic characterization of EL4 lymphoma-derived tumors upon chemotherapy treatment reveals potential roles for lysosomes and caspase-6 during tumor cell death in vivo

The murine mouse lymphoblastic lymphoma cell line (EL4) tumor model is an established in vivo apoptosis model for the investigation of novel cancer imaging agents and immunological treatments due to the rapid and significant response of the EL4 tumors to cyclophosphamide and etoposide combination chemotherapy. Despite the utility of this model system in cancer research, little is known regarding the molecular details of in vivo tumor cell death. Here, we report the first in-depth quantitative proteomic analysis of the changes that occur in these tumors upon cyclophosphamide and etoposide treatment in vivo. Using a label-free quantitative proteomic approach a total of 5838 proteins were identified in the treated and untreated tumors, of which 875 were determined to change in abundance with statistical significance. Initial analysis of the data reveals changes that may have been predicted, such as the downregulation of ribosomes, but demonstrates the robustness of the dataset. Analysis of the dataset also reveals the unexpected downregulation of caspase-3 and an upregulation of caspase-6 in addition to a global upregulation of lysosomal proteins in the bulk of the tumor.

Macrophage NOS2 in Tumor Leukocytes

SIGNIFICANCE

Leukocytes and especially macrophages are a major cellular constituent of the tumor mass. The tumor microenvironment not only determines their activity but in turn these cells also contribute to tumor initiation and progression. Recent Advances: Proinflammatory stimulated macrophages upregulate inducible nitric oxide synthase (NOS2) and produce high steady-state NO concentrations. NO provokes tumor cell death by initiating apoptosis and/or necrosis. Mechanisms may comprise p53 accumulation, immunestimulatory activities, and an increased efficacy of chemo- and/or radiotherapy. However, the potential cytotoxic activity of macrophages often is compromised in the tumor microenvironment and instead a protumor activity of macrophages dominates. Contributing factors are signals generated by viable and dying tumor cells, attraction and activation of myeloid-derived suppressor cells, and hypoxia. Limited oxygen availability not only attenuates NOS2 activity but also causes accumulation of hypoxia-inducible factors 1 and 2 (HIF-1/HIF-2). Activation of the HIF system is tightly linked to NO formation and affects the expression of macrophage phenotype markers that in turn add to tumor progression.

CRITICAL ISSUES

To make use of the cytotoxic arsenal of activated macrophages directed against tumor cells, it will be critical to understand how, when, and where these innate immune responses are blocked and whether it will be possible to reinstall their full capacity to kill tumor cells.

FUTURE DIRECTIONS

Low-dose irradiation or proinflammatory activation of macrophages in the tumor microenvironment may open options to boost NOS2 expression and activity and to initiate immunestimulatory features of NO that may help to restrict tumor growth. Antioxid. Redox Signal. 26, 1023-1043.

Nitric Oxide Synthase-2-Derived Nitric Oxide Drives Multiple Pathways of Breast Cancer Progression

SIGNIFICANCE

Breast cancer is the second leading cause of cancer-related deaths among women in the United States. Development and progression of malignancy are associated with diverse cell signaling pathways that control cell proliferation, survival, motility, invasion, and metastasis. Recent Advances: An increasing number of clinical studies have implicated a strong relationship between elevated tumor nitric oxide synthase-2 (NOS2) expression and poor patient survival.

CRITICAL ISSUES

Herein, we review what we believe to be key mechanisms in the role(s) of NOS2-derived nitric oxide (NO) as a driver of breast cancer disease progression. High NO increases cyclooxygenase-2 activity, hypoxia inducible factor-1 alpha protein stabilization, and activation of important cell signaling pathways, including phosphoinositide 3-kinase/protein kinase B, mitogen-activated protein kinase, epidermal growth factor receptor, and Ras, through post-translational protein modifications. Moreover, dysregulated NO flux within the tumor microenvironment has other important roles, including the promotion of angiogenesis and modulation of matrix metalloproteinase/tissue inhibitor matrix metalloproteinase associated with tumor progression.

FUTURE DIRECTIONS

The elucidation of these and other NO-driven pathways implicates NOS2 as a key driver of breast cancer disease progression and provides a new perspective in the identification of novel targets that may be therapeutically beneficial in the treatment of estrogen receptor-negative disease. Antioxid. Redox Signal. 26, 1044-1058.

Tumor Microenvironment Activated Membrane Fusogenic Liposome with Speedy Antibody and Doxorubicin Delivery for Synergistic Treatment of Metastatic Tumors

Metastasis is the principal event leading to breast cancer death. Discovery of novel therapeutic approaches that are specific in targeting tumor metastasis factors while at the same time are an effective treatment of the tumor is urgently required. S100A4 protein is a key player in promoting metastasis and sequestrating the effect of tumor-suppressor protein p53. Here, a tumor microenvironment activated membrane fusogenic liposome was prepared to deliver rapidly anti-S100A4 antibody and doxorubicin into the cytoplasm directly in a fusion-dependent manner in order to bypass the cellular endocytosis to avoid the inefficient escape and degradation in the acidic endosome. After intracellular S100A4 blockage with anti-S100A4 antibody, the cytoskeleton of breast cancer 4T1 cells was rearranged and cell motility was suppressed. In the meantime, the antitumor effect of doxorubicin was enormously enhanced by reversing the effect of S100A4 on the sequestration of tumor-suppressor protein p53. Importantly, both local growth and metastasis of 4T1 cells were inhibited in a xenograft mouse model. Together, the speedy delivery of antibody and doxorubicin into cytoplasm based on a new membrane fusogenic liposome was an innovative approach for metastatic breast cancer treatment.

The pre-rRNA processing factor DEF is rate limiting for the pathogenesis of MYCN-driven neuroblastoma

The nucleolar factor, digestive organ expansion factor (DEF), has a key role in ribosome biogenesis, functioning in pre-ribosomal RNA (pre-rRNA) processing as a component of the small ribosomal subunit (SSU) processome. Here we show that the peripheral sympathetic nervous system (PSNS) is very underdeveloped in def-deficient zebrafish, and that def haploinsufficiency significantly decreases disease penetrance and tumor growth rate in a MYCN-driven transgenic zebrafish model of neuroblastoma that arises in the PSNS. Consistent with these findings, DEF is highly expressed in human neuroblastoma, and its depletion in human neuroblastoma cell lines induces apoptosis. Interestingly, overexpression of MYCN in zebrafish and in human neuroblastoma cells results in the appearance of intermediate pre-rRNAs species that reflect the processing of pre-rRNAs through Pathway 2, a pathway that processes pre-rRNAs in a different temporal order than the more often used Pathway 1. Our results indicate that DEF and possibly other components of the SSU processome provide a novel site of vulnerability in neuroblastoma cells that could be exploited for targeted therapy.

Evolution of the archaeal and mammalian information processing systems: towards an archaeal model for human disease

Current evolutionary models suggest that Eukaryotes originated from within Archaea instead of being a sister lineage. To test this model of ancient evolution, we review recent studies and compare the three major information processing subsystems of replication, transcription and translation in the Archaea and Eukaryotes. Our hypothesis is that if the Eukaryotes arose within the archaeal radiation, their information processing systems will appear to be one of kind and not wholly original. Within the Eukaryotes, the mammalian or human systems are emphasized because of their importance in understanding health. Biochemical as well as genetic studies provide strong evidence for the functional similarity of archaeal homologs to the mammalian information processing system and their dissimilarity to the bacterial systems. In many independent instances, a simple archaeal system is functionally equivalent to more elaborate eukaryotic homologs, suggesting that evolution of complexity is likely an central feature of the eukaryotic information processing system. Because fewer components are often involved, biochemical characterizations of the archaeal systems are often easier to interpret. Similarly, the archaeal cell provides a genetically and metabolically simpler background, enabling convenient studies on the complex information processing system. Therefore, Archaea could serve as a parsimonious and tractable host for studying human diseases that arise in the information processing systems.

Role of RPL39 in Metaplastic Breast Cancer

Background: Metaplastic breast cancer is one of the most therapeutically challenging forms of breast cancer because of its highly heterogeneous and chemoresistant nature. We have previously demonstrated that ribosomal protein L39 (RPL39) and its gain-of-function mutation A14V have oncogenic activity in triple-negative breast cancer and this activity may be mediated through inducible nitric oxide synthase (iNOS). The function of RPL39 and A14V in other breast cancer subtypes is currently unknown. The objective of this study was to determine the role and mechanism of action of RPL39 in metaplastic breast cancer.

Methods: Both competitive allele-specific and droplet digital polymerase chain reaction were used to determine the RPL39 A14V mutation rate in metaplastic breast cancer patient samples. The impact of RPL39 and iNOS expression on patient overall survival was estimated using the Kaplan-Meier method. Co-immunoprecipitation and immunoblot analyses were used for mechanistic evaluation of RPL39.

Results: The RPL39 A14V mutation rate was 97.5% (39/40 tumor samples). High RPL39 (hazard ratio = 0.71, 95% confidence interval = 0.55 to 0.91, P = .006) and iNOS expression (P = .003) were associated with reduced patient overall survival. iNOS inhibition with the pan-NOS inhibitor N^G-methyl-L-arginine acetate decreased in vitro proliferation and migration, in vivo tumor growth in both BCM-4664 and BCM-3807 patient-derived xenograft models (P = .04 and P = .02, respectively), and in vitro and in vivo chemoresistance. Mechanistically, RPL39 mediated its cancer-promoting actions through iNOS signaling, which was driven by the RNA editing enzyme adenosine deaminase acting on RNA 1.

Conclusion: NOS inhibitors and RNA editing modulators may offer novel treatment options for metaplastic breast cancer.

Transcriptome profiling in oral cavity and esophagus tissues from (S)-N'-nitrosonornicotine-treated rats reveals candidate genes involved in human oral cavity and esophageal carcinogenesis

Recently, we have shown that (S)-N'-Nitrosonornicotine [(S)-NNN], the major form of NNN in tobacco products, is a potent oral cavity and esophageal carcinogen in rats. To determine the early molecular alterations induced by (S)-NNN in the oral and esophageal mucosa, we administered the carcinogen to rats in the drinking water for 10 wk and global gene expression alterations were analyzed by RNA sequencing. At a false discovery rate P-value < 0.05 and fold-change ≥2, we found alterations in the level of 39 genes in the oral cavity and 69 genes in the esophagus. Validation of RNA sequencing results by qRT-PCR assays revealed a high cross-platform concordance. The most significant impact of exposure to (S)-NNN was alteration of genes involved in immune regulation (Aire, Ctla4, and CD80), inflammation (Ephx2 and Inpp5d) and cancer (Cdkn2a, Dhh, Fetub B, Inpp5d, Ly6E, Nr1d1, and Wnt6). Consistent with the findings in rat tissues, most of the genes were deregulated, albeit to different degrees, in immortalized oral keratinocytes treated with (S)-NNN and in non-treated premalignant oral cells and malignant oral and head and neck squamous cells. Furthermore, interrogation of TCGA data sets showed that genes deregulated by (S)-NNN in rat tissues (Fetub, Ly6e, Nr1d1, Cacna1c, Cd80, and Dgkg) are also altered in esophageal and head and neck tumors. Overall, our findings provide novel insights into early molecular changes induced by (S)-NNN and, therefore, could contribute to the development of biomarkers for the early detection and prevention of (S)-NNN-associated oral and esophageal cancers. © 2016 Wiley Periodicals, Inc.

Targeted Delivery of Shear Stress-Inducible Micrornas by Nanoparticles to Prevent Vulnerable Atherosclerotic Lesions

Atherosclerosis is a chronic inflammatory vascular wall disease, and endothelial cell dysfunction plays an important role in its development and progression. Under the influence of laminar shear stress, however, the endothelium releases homeostatic factors such as nitric oxide and expresses of vasoprotective microRNAs that are resistant to atherosclerosis. Adhesion molecules such as E-selectin, exhibited on the endothelial surface, recruit monocytes that enter the vessel wall to form foam cells. Accumulation of these foam cells form fatty streaks that may progress to atherosclerotic plaques in the blood vessel wall. Interestingly, E-selectin may also serve as an affinity moiety for targeted drug delivery against atherosclerosis. We have recently developed an E-selectin-targeted platform that enriches therapeutic microRNAs in the inflamed endothelium to inhibit formation of vulnerable atherosclerotic plaques.

A pyruvate decarboxylase-mediated therapeutic strategy for mimicking yeast metabolism in cancer cells

Cancer cells have high rates of glycolysis and lactic acid fermentation in order to fuel accelerated rates of cell division (Warburg effect). Here, we present a strategy for merging cancer and yeast metabolism to remove pyruvate, a key intermediate of cancer cell metabolism, and produce the toxic compound acetaldehyde. This approach was achieved by administering the yeast enzyme pyruvate decarboxylase to triple negative breast cancer cells. To overcome the challenges of protein delivery, a nanoparticle-based system consisting of cationic lipids and porous silicon were employed to obtain efficient intracellular uptake. The results demonstrate that the enzyme therapy decreases cancer cell viability through production of acetaldehyde and reduction of lactic acid fermentation.

In Vivo Genetic Screens of Patient-Derived Tumors Revealed Unexpected Frailty of the Transformed Phenotype

The identification of genes maintaining cancer growth is critical to our understanding of tumorigenesis. We report the first in vivo genetic screen of patient-derived tumors, using metastatic melanomas and targeting 236 chromatin genes by expression of specific shRNA libraries. Our screens revealed unprecedented numerosity of genes indispensable for tumor growth (∼50% of tested genes) and unexpected functional heterogeneity among patients (<15% in common). Notably, these genes were not activated by somatic mutations in the same patients and are therefore distinguished from mutated cancer driver genes. We analyzed underlying molecular mechanisms of one of the identified genes, the Histone-lysine N-methyltransferase KMT2D, and showed that it promotes tumorigenesis by dysregulating a subset of transcriptional enhancers and target genes involved in cell migration. The assembly of enhancer genomic patterns by activated KMT2D was highly patient-specific, regardless of the identity of transcriptional targets, suggesting that KMT2D might be activated by distinct upstream signaling pathways.

SIGNIFICANCE

Drug targeting of biologically relevant cancer-associated mutations is considered a critical strategy to control cancer growth. Our functional in vivo genetic screens of patient-derived tumors showed unprecedented numerosity and interpatient heterogeneity of genes that are essential for tumor growth, but not mutated, suggesting that multiple, patient-specific signaling pathways are activated in tumors. Cancer Discov; 6(6); 650-63. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 561.

The Potential Role of Nitric Oxide in Halting Cancer Progression Through Chemoprevention

Nitric oxide (NO) in general plays a beneficial physiological role as a vasorelaxant and the role of NO is decided by its concentration present in physiological environments. NO either facilitates cancer-promoting characters or act as an anti-cancer agent. The dilemma in this regard still remains unanswered. This review summarizes the recent information on NO and its role in carcinogenesis and tumor progression, as well as dietary chemopreventive agents which have NO-modulating properties with safe cytotoxic profile. Understanding the molecular mechanisms and cross-talk modulating NO effect by these chemopreventive agents can allow us to develop better therapeutic strategies for cancer treatment.

Role of ribosomal protein mutations in tumor development (Review)

Ribosomes are cellular machines essential for protein synthesis. The biogenesis of ribosomes is a highly complex and energy consuming process that initiates in the nucleolus. Recently, a series of studies applying whole-exome or whole-genome sequencing techniques have led to the discovery of ribosomal protein gene mutations in different cancer types. Mutations in ribosomal protein genes have for example been found in endometrial cancer (RPL22), T-cell acute lymphoblastic leukemia (RPL10, RPL5 and RPL11), chronic lymphocytic leukemia (RPS15), colorectal cancer (RPS20), and glioma (RPL5). Moreover, patients suffering from Diamond-Blackfan anemia, a bone marrow failure syndrome caused by mutant ribosomal proteins are also at higher risk for developing leukemia, or solid tumors. Different experimental models indicate potential mechanisms whereby ribosomal proteins may initiate cancer development. In particular, deregulation of the p53 tumor suppressor network and altered mRNA translation are mechanisms likely to be involved. We envisage that changes in expression and the occurrence of ribosomal protein gene mutations play important roles in cancer development. Ribosome biology constitutes a re-emerging vital area of basic and translational cancer research.

Significance of twist and iNOS expression in human breast carcinoma

Twist is a basic helix-loop-helix transcription factor family normally expressed during embryonic development and apparently activated in variety of tumours. Overexpression of twist is correlated with uncontrolled cell proliferation, differentiation, invasion and metastasis. Twist expression is associated with oestrogen receptor (ER); however, the molecular mechanism behind involvement of twist in progression of breast cancer is still unclear. Nitric oxide synthases (NOSs) which cause damage to the cellular DNA are also shown to be involved in cancer progression. The present study involves total number of n = 85 breast biopsies, which include 19 non-cancer and 66 cancerous lesions. We analysed twist, iNOS and ER expression pattern in human breast carcinomas by RT-PCR and also analysed twist cellular localisation by immunohistochemical analysis. iNOS expression pattern was correlated with different stages of breast carcinoma. Twist expression was significantly increased in cancer lesions when compared to the non-cancer. The breast cancer lesions positive to ER showed positivity to twist (72%) as well. The higher stages of cancer lesions showed a significant expression of twist localised in cytoplasm of the cancer cells. Collectively these data indicate that up-regulation of twist is correlated with the ER presenting breast cancer, and iNOS expression was positively correlated with tumour-node metastasis (TNM) staging of breast cancer. These findings suggest that expression of twist and iNOS may have a functional role in cancer progression.

Multistage vector (MSV) therapeutics

One of the greatest challenges in the field of medicine is obtaining controlled distribution of systemically administered therapeutic agents within the body. Indeed, biological barriers such as physical compartmentalization, pressure gradients, and excretion pathways adversely affect localized delivery of drugs to pathological tissue. The diverse nature of these barriers requires the use of multifunctional drug delivery vehicles that can overcome a wide range of sequential obstacles. In this review, we explore the role of multifunctionality in nanomedicine by primarily focusing on multistage vectors (MSVs). The MSV is an example of a promising therapeutic platform that incorporates several components, including a microparticle, nanoparticles, and small molecules. In particular, these components are activated in a sequential manner in order to successively address transport barriers.

Multistage vector delivery of sulindac and silymarin for prevention of colon cancer

Familial adenomatous polyposis (FAP) is an inherited condition secondary to germline mutations in the APC gene, thus resulting in the formation of hundreds of colonic adenomas that eventually progress into colon cancer. Surgical removal of the colon remains the only treatment option to avoid malignancy, as long-term exposure to chemopreventive agents such as sulindac (a non-steroidal anti-inflammatory drug) and silymarin (phytoestrogen) is not feasible. Here, we have developed a multistage silicon-based drug delivery platform for sulindac and silymarin that preferentially interacts with colon cancer cells as opposed to normal intestinal mucosa. Preferential binding and internalization of these drugs into colon cancer cells was obtained using a targeting strategy against the protein meprin A, which we demonstrate is overexpressed in human colon cancer cells and in the small intestine of Apc(Min/+) mice. We propose that this delivery system could potentially be used to reduce drug-induced side effects in FAP patients, thus enabling long-term prevention of adenoma formation.

Differential Stoichiometry among Core Ribosomal Proteins

Understanding the regulation and structure of ribosomes is essential to understanding protein synthesis and its dysregulation in disease. While ribosomes are believed to have a fixed stoichiometry among their core ribosomal proteins (RPs), some experiments suggest a more variable composition. Testing such variability requires direct and precise quantification of RPs. We used mass spectrometry to directly quantify RPs across monosomes and polysomes of mouse embryonic stem cells (ESC) and budding yeast. Our data show that the stoichiometry among core RPs in wild-type yeast cells and ESC depends both on the growth conditions and on the number of ribosomes bound per mRNA. Furthermore, we find that the fitness of cells with a deleted RP-gene is inversely proportional to the enrichment of the corresponding RP in polysomes. Together, our findings support the existence of ribosomes with distinct protein composition and physiological function.

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Wild-type yeast and mouse cells build ribosomes with different protein composition

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The stoichiometry among ribosomal proteins (RP) correlates to growth rate

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RP stoichiometry depends on the number of ribosomes bound per mRNA

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RP stoichiometry depends on the growth conditions

Principles of nanoparticle design for overcoming biological barriers to drug delivery

Biological barriers to drug transport prevent successful accumulation of nanotherapeutics specifically at diseased sites, limiting efficacious responses in disease processes ranging from cancer to inflammation. Although substantial research efforts have aimed to incorporate multiple functionalities and moieties within the overall nanoparticle design, many of these strategies fail to adequately address these barriers. Obstacles, such as nonspecific distribution and inadequate accumulation of therapeutics, remain formidable challenges to drug developers. A reimagining of conventional nanoparticles is needed to successfully negotiate these impediments to drug delivery. Site-specific delivery of therapeutics will remain a distant reality unless nanocarrier design takes into account the majority, if not all, of the biological barriers that a particle encounters upon intravenous administration. By successively addressing each of these barriers, innovative design features can be rationally incorporated that will create a new generation of nanotherapeutics, realizing a paradigmatic shift in nanoparticle-based drug delivery.

Spotlights on immunological effects of reactive nitrogen species: When inflammation says nitric oxide

Over the last decades, nitric oxide (NO) has been definitively recognised as one of the key players involved in immunity and inflammation. NO generation was originally described in activated macrophages, which still represent the prototype of NO-producing cells. Notwithstanding, additional cell subsets belonging to both innate and adaptive immunity have been documented to sustain NO propagation by means of the enzymatic activity of different nitric oxide synthase isoforms. Furthermore, due to its chemical characteristics, NO could rapidly react with other free radicals to generate different reactive nitrogen species (RNS), which have been intriguingly associated with many pathological conditions. Nonetheless, the plethora of NO/RNS-mediated effects still remains extremely puzzling. The aim of this manuscript is to dig into the broad literature on the topic to provide intriguing insights on NO-mediated circuits within immune system. We analysed NO and RNS immunological clues arising from their biochemical properties, immunomodulatory activities and finally dealing with their impact on different pathological scenarios with far prompting intriguing perspectives for their pharmacological targeting.

Porous silicon microparticle potentiates anti-tumor immunity by enhancing cross-presentation and inducing type I interferon response

Micro- and nanometer-size particles have become popular candidates for cancer vaccine adjuvants. However, the mechanism by which such particles enhance immune responses remains unclear. Here, we report a porous silicon microparticle (PSM)-based cancer vaccine that greatly enhances cross-presentation and activates type I interferon (IFN-I) response in dendritic cells (DCs). PSM-loaded antigen exhibited prolonged early endosome localization and enhanced cross-presentation through both proteasome- and lysosome-dependent pathways. Phagocytosis of PSM by DCs induced IFN-I responses through a TRIF- and MAVS-dependent pathway. DCs primed with PSM-loaded HER2 antigen produced robust CD8 T cell-dependent anti-tumor immunity in mice bearing HER2+ mammary gland tumors. Importantly, this vaccination activated the tumor immune microenvironment with elevated levels of intra-tumor IFN-I and MHCII expression, abundant CD11c+ DC infiltration, and tumor-specific cytotoxic T cell responses. These findings highlight the potential of PSM as an immune adjuvant to potentiate DC-based cancer immunotherapy.

Activating PIK3CA Mutations Induce an Epidermal Growth Factor Receptor (EGFR)/Extracellular Signal-regulated Kinase (ERK) Paracrine Signaling Axis in Basal-like Breast Cancer

Mutations in PIK3CA, the gene encoding the p110α catalytic subunit of phosphoinositide 3-kinase (PI3K) have been shown to transform human mammary epithelial cells (MECs). These mutations are present in all breast cancer subtypes, including basal-like breast cancer (BLBC). Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we identified 72 protein expression changes in human basal-like MECs with knock-in E545K or H1047R PIK3CA mutations versus isogenic MECs with wild-type PIK3CA. Several of these were secreted proteins, cell surface receptors or ECM interacting molecules and were required for growth of PIK3CA mutant cells as well as adjacent cells with wild-type PIK3CA. The proteins identified by MS were enriched among human BLBC cell lines and pointed to a PI3K-dependent amphiregulin/EGFR/ERK signaling axis that is activated in BLBC. Proteins induced by PIK3CA mutations correlated with EGFR signaling and reduced relapse-free survival in BLBC. Treatment with EGFR inhibitors reduced growth of PIK3CA mutant BLBC cell lines and murine mammary tumors driven by a PIK3CA mutant transgene, all together suggesting that PIK3CA mutations promote tumor growth in part by inducing protein changes that activate EGFR.

Improving cancer therapy by targeting cancer stem cells: Directions, challenges, and clinical results

Cancer stem cells (CSC) are a rare cell population within a tumor characterized by the ability to form tumors following injection into an immunocompromised host. While the role of CSC has been clearly established in animal models, evidence of their clinical relevance has been harder to demonstrate. A number of markers, or combination thereof, have been used to detect and measure, although non-specifically, CSC in almost all human tumors. Several pathways have been identified as crucial for, but not necessarily unique to, CSC survival and proliferation, and novel agents have been designed to target such pathways. A number of such agents have entered early phase development. Further, drugs that have long been marketed for non-oncological indications have been redirected to oncology as they appear to affect one or more of such pathways. This article aims to review the available evidence on the clinical relevance of CSC from a drug development standpoint and the results of early phase clinical trials of agents interfering with the above pathways. It also discusses limitations of current clinical trial design and endpoints to demonstrate anti-CSC activity as well as possible strategies to overcome these limitations.

Whole-genome RNAi screen highlights components of the endoplasmic reticulum/Golgi as a source of resistance to immunotoxin-mediated cytotoxicity

Immunotoxins (antibody-toxin fusion proteins) target surface antigens on cancer cells and kill these cells via toxin-mediated inhibition of protein synthesis. To identify genes controlling this process, an RNAi whole-genome screen (∼ 22,000 genes at three siRNAs per gene) was conducted via monitoring the cytotoxicity of the mesothelin-directed immunotoxin SS1P. SS1P, a Pseudomonas exotoxin-based immunotoxin, was chosen because it is now in clinical trials and has produced objective tumor regressions in patients. High and low concentrations of SS1P were chosen to allow for the identification of both mitigators and sensitizers. As expected, silencing known essential genes in the immunotoxin pathway, such as mesothelin, furin, KDEL receptor 2, or members of the diphthamide pathway, protected cells. Of greater interest was the observation that many RNAi targets increased immunotoxin sensitivity, indicating that these gene products normally contribute to inefficiencies in the killing pathway. Of the top sensitizers, many genes encode proteins that locate to either the endoplasmic reticulum (ER) or Golgi and are annotated as part of the secretory system. Genes related to the ER-associated degradation system were not among high-ranking mitigator or sensitizer candidates. However, the p97 inhibitor eeyarestatin 1 enhanced immunotoxin killing. Our results highlight potential targets for chemical intervention that could increase immunotoxin killing of cancer cells and enhance our understanding of toxin trafficking.

Inhibition of iNOS as a novel effective targeted therapy against triple-negative breast cancer

Introduction

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer with no effective targeted therapy. Inducible nitric oxide synthase (iNOS) is associated with poor survival in patients with breast cancer by increasing tumor aggressiveness. This work aimed to investigate the potential of iNOS inhibitors as a targeted therapy for TNBC. We hypothesized that inhibition of endogenous iNOS would decrease TNBC aggressiveness by reducing tumor initiation and metastasis through modulation of epithelial-mesenchymal transition (EMT)-inducing factors.

Methods

iNOS protein levels were determined in 83 human TNBC tissues and correlated with clinical outcome. Proliferation, mammosphere-forming efficiency, migration, and EMT transcription factors were assessed in vitro after iNOS inhibition. Endogenous iNOS targeting was evaluated as a potential therapy in TNBC mouse models.

Results

High endogenous iNOS expression was associated with worse prognosis in patients with TNBC by gene expression as well as immunohistochemical analysis. Selective iNOS (1400 W) and pan-NOS (L-NMMA and L-NAME) inhibitors diminished cell proliferation, cancer stem cell self-renewal, and cell migration in vitro, together with inhibition of EMT transcription factors (Snail, Slug, Twist1, and Zeb1). Impairment of hypoxia-inducible factor 1α, endoplasmic reticulum stress (IRE1α/XBP1), and the crosstalk between activating transcription factor 3/activating transcription factor 4 and transforming growth factor β was observed. iNOS inhibition significantly reduced tumor growth, the number of lung metastases, tumor initiation, and self-renewal.

Conclusions

Considering the effectiveness of L-NMMA in decreasing tumor growth and enhancing survival rate in TNBC, we propose a targeted therapeutic clinical trial by re-purposing the pan-NOS inhibitor L-NMMA, which has been extensively investigated for cardiogenic shock as an anti-cancer therapeutic.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-015-0527-x) contains supplementary material, which is available to authorized users.

Three-dimensional in vitro co-culture model of breast tumor using magnetic levitation

In this study, we investigate a novel in vitro model to mimic heterogeneous breast tumors without the use of a scaffold while allowing for cell-cell and tumor-fibroblast interactions. Previous studies have shown that magnetic levitation system under conventional culturing conditions results in the formation of three-dimensional (3D) structures, closely resembling in vivo tissues (fat tissue, vasculature, etc.). Three-dimensional heterogeneous tumor models for breast cancer were designed to effectively model the influences of the tumor microenvironment on drug efficiency. Various breast cancer cells were co-cultured with fibroblasts and then magnetically levitated. Size and cell density of the resulting tumors were measured. The model was phenotypically compared to in vivo tumors and examined for the presence of ECM proteins. Lastly, the effects of tumor stroma in the 3D in vitro model on drug transport and efficiency were assessed. Our data suggest that the proposed 3D in vitro breast tumor is advantageous due to the ability to: (1) form large-sized (millimeter in diameter) breast tumor models within 24 h; (2) control tumor cell composition and density; (3) accurately mimic the in vivo tumor microenvironment; and (4) test drug efficiency in an in vitro model that is comparable to in vivo tumors.

[Relaxing of unity and membership democracy in the Danish Nursing Council]

Breast cancer patients with high expression of aldehyde dehydrogenases (ALDHs) cell population have higher tolerability to chemotherapy since the cells posses a characteristic of breast cancer stem cells (BCSCs) that are resistant to conventional chemotherapy. In this study, we found that the ALDH‐positive cells were higher in CD44⁺CD24⁻ and CD44⁺CD24⁻ESA⁺BCSCs than that in both BT549 and MDA‐MB‐231 cell lines but microRNA‐7 (miR‐7) level was lower in CD44⁺CD24⁻ and CD44⁺CD24⁻ESA⁺BCSCs than that in MDA‐MB‐231 cells. Moreover, miR‐7 overexpression in MDA‐MB‐231 cells decreased ALDH1A3 activity by miR‐7 directly binding to the 3′‐untranslated region of ALDH1A3; while the ALDH1A3 expression was downregulated in MDA‐MB‐231 cells, the expressions of CD44 and Epithelium Specific Antigen (ESA) were reduced along with decreasing the BCSC subpopulation. Significantly, enforced expression of miR‐7 in CD44⁺CD24⁻ESA⁺BCSC markedly inhibited the BCSC‐driven xenograft growth in mice by decreasing an expression of ALDH1A3. Collectively, the findings demonstrate the miR‐7 inhibits breast cancer growth via suppressing ALDH1A3 activity concomitant with decreasing BCSC subpopulation. This approach may be considered for an investigation on clinical treatment of breast cancers.