STAT3 acts through pre-existing nucleosome-depleted regions bound by FOS during an epigenetic switch linking inflammation to cancer

MafB, WDR77, and ß-catenin interact with each other and have similar genome association profiles

MafB (a bZIP transcription factor), ß-catenin (the ultimate target of the Wnt signal transduction pathway that acts as a transcriptional co-activator of LEF/TCF proteins), and WDR77 (a transcriptional co-activator of multiple hormone receptors) are important for breast cellular transformation. Unexpectedly, these proteins interact directly with each other, and they have similar genomic binding profiles. Furthermore, while some of these common target sites coincide with those bound by LEF/TCF, the majority are located just downstream of transcription initiation sites at a position near paused RNA polymerase (Pol II) and the +1 nucleosome. Occupancy levels of these factors at these promoter-proximal sites are strongly correlated with the level of paused Pol II and transcriptional activity.

STAT3 Signaling in Breast Cancer: Multicellular Actions and Therapeutic Potential

Simple Summary

Many signaling pathways are overactive in breast cancer, and among them is the STAT3 signaling pathway. STAT3 is activated by secreted factors within the breast tumor, many of which are elevated and correlate to advanced disease and poor survival outcomes. This review examines how STAT3 signaling is activated in breast cancer by the proinflammatory, gp130 cytokines, interleukins 6 and 11. We evaluate how this signaling cascade functions in the various cells of the tumor microenvironment to drive disease progression and metastasis. We discuss how our understanding of these processes may lead to the development of novel therapeutics to tackle advanced disease.

Abstract

Interleukin (IL)-6 family cytokines, such as IL-6 and IL-11, are defined by the shared use of the gp130 receptor for the downstream activation of STAT3 signaling and the activation of genes which contribute to the “hallmarks of cancer”, including proliferation, survival, invasion and metastasis. Increased expression of these cytokines, or the ligand-specific receptors IL-6R and IL-11RA, in breast tumors positively correlate to disease progression and poorer patient outcome. In this review, we examine evidence from pre-clinical studies that correlate enhanced IL-6 and IL-11 mediated gp130/STAT3 signaling to the progression of breast cancer. Key processes by which the IL-6 family cytokines contribute to the heterogeneous nature of breast cancer, immune evasion and metastatic potential, are discussed. We examine the latest research into the therapeutic targeting of IL-6 family cytokines that inhibit STAT3 transcriptional activity as a potential breast cancer treatment, including current clinical trials. The importance of the IL-6 family of cytokines in cellular processes that promote the development and progression of breast cancer warrants further understanding of the molecular basis for its actions to help guide the development of future therapeutic targets.

Different SP1 binding dynamics at individual genomic loci in human cells

Using a tamoxifen-inducible time-course ChIP-sequencing (ChIP-seq) approach, we show that the ubiquitous transcription factor SP1 has different binding dynamics at its target sites in the human genome. SP1 very rapidly reaches maximal binding levels at some sites, but binding kinetics at other sites is biphasic, with rapid half-maximal binding followed by a considerably slower increase to maximal binding. While ∼70% of SP1 binding sites are located at promoter regions, loci with slow SP1 binding kinetics are enriched in enhancer and Polycomb-repressed regions. Unexpectedly, SP1 sites with fast binding kinetics tend to have higher quality and more copies of the SP1 sequence motif. Different cobinding factors associate near SP1 binding sites depending on their binding kinetics and on their location at promoters or enhancers. For example, NFY and FOS are preferentially associated near promoter-bound SP1 sites with fast binding kinetics, whereas DNA motifs of ETS and homeodomain proteins are preferentially observed at sites with slow binding kinetics. At promoters but not enhancers, proteins involved in sumoylation and PML bodies associate more strongly with slow SP1 binding sites than with the fast binding sites. The speed of SP1 binding is not associated with nucleosome occupancy, and it is not necessarily coupled to higher transcriptional activity. These results with SP1 are in contrast to those of human TBP, indicating that there is no common mechanism affecting transcription factor binding kinetics. The biphasic kinetics at some SP1 target sites suggest the existence of distinct chromatin states at these loci in different cells within the overall population.

STAT3 as a mediator of oncogenic cellular metabolism: Pathogenic and therapeutic implications

The oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) is activated constitutively in a wide array of human cancers. It is an appealing molecular target for novel therapy as it directly regulates expression of genes involved in cell proliferation, survival, angiogenesis, chemoresistance and immune responsiveness. In addition to these well-established oncogenic roles, STAT3 has also been found to mediate a wide array of functions in modulating cellular behavior. The transcriptional function of STAT3 is canonically regulated through tyrosine phosphorylation. However, STAT3 phosphorylated at a single serine residue can allow incorporation of this protein into the inner mitochondrial membrane to support oxidative phosphorylation (OXPHOS) and maximize the utility of glucose sources. Conflictingly, its canonical transcriptional activity suppresses OXPHOS and favors aerobic glycolysis to promote oncogenic behavior. Apart from mediating the energy metabolism and controversial effects on ATP production, STAT3 signaling modulates lipid metabolism of cancer cells. By mediating fatty acid synthesis and beta oxidation, STAT3 promotes employment of available resources and supports survival in the conditions of metabolic stress. Thus, the functions of STAT3 extend beyond regulation of oncogenic genes expression to pleiotropic effects on a spectrum of essential cellular processes. In this review, we dissect the current knowledge on activity and mechanisms of STAT3 involvement in transcriptional regulation, mitochondrial function, energy production and lipid metabolism of malignant cells, and its implications to cancer pathogenesis and therapy.

YAP and TAZ are transcriptional co-activators of AP-1 proteins and STAT3 during breast cellular transformation

The YAP and TAZ paralogs are transcriptional co-activators recruited to target sites by TEAD proteins. Here, we show that YAP and TAZ are also recruited by JUNB (a member of the AP-1 family) and STAT3, key transcription factors that mediate an epigenetic switch linking inflammation to cellular transformation. YAP and TAZ directly interact with JUNB and STAT3 via a WW domain important for transformation, and they stimulate transcriptional activation by AP-1 proteins. JUNB, STAT3, and TEAD co-localize at virtually all YAP/TAZ target sites, yet many target sites only contain individual AP-1, TEAD, or STAT3 motifs. This observation and differences in relative crosslinking efficiencies of JUNB, TEAD, and STAT3 at YAP/TAZ target sites suggest that YAP/TAZ is recruited by different forms of an AP-1/STAT3/TEAD complex depending on the recruiting motif. The different classes of YAP/TAZ target sites are associated with largely non-overlapping genes with distinct functions. A small minority of target sites are YAP- or TAZ-specific, and they are associated with different sequence motifs and gene classes from shared YAP/TAZ target sites. Genes containing either the AP-1 or TEAD class of YAP/TAZ sites are associated with poor survival of breast cancer patients with the triple-negative form of the disease.

LIF maintains mouse embryonic stem cells pluripotency by modulating TET1 and JMJD2 activity in a JAK2-dependent manner

The LIF-JAK2-STAT3 pathway is the central signal transducer that maintains undifferentiated mouse embryonic stem cells (mESCs), which is achieved by the recruitment of activated STAT3 to the master pluripotency genes and activation of the gene transcriptions. It remains unclear, however, how the epigenetic status required for the master gene transcriptions is built into LIF-treated mESC cultures. In this study, Jak2, but not Stat3, in the LIF canonical pathway, establishes an open epigenetic status in the pluripotency gene promoter regions. Upon LIF activation, cytosolic JAK2 was translocalized into the nucleus of mESCs, and reduced DNA methylation (5mC levels) along with increasing DNA hydroxymethylation (5hmC) in the pluripotent gene (Nanog/Pou5f1) promoter regions. In addition, the repressive histone codes H3K9m3/H3K27m3 were reduced by JAK2. Activated JAK2 directly interacted with the core epigenetic enzymes TET1 and JMJD2, modulating its activity and promotes the DNA and histone demethylation, respectively. The JAK2 effects were attained by tyrosine phosphorylation on the epigenetic enzymes. The effects of JAK2 phosphorylation on the enzymes were diverse, but all were merged to the epigenetic signatures associated with open DNA/chromatin structures. Taken together, these results reveal a previously unrecognized epigenetic regulatory role of JAK2 as an important mediator of mESC maintenance.

S100A8/S100A9 cytokine acts as a transcriptional coactivator during breast cellular transformation

Cytokines are extracellular proteins that convey messages between cells by interacting with cognate receptors at the cell surface and triggering signaling pathways that alter gene expression and other phenotypes in an autocrine or paracrine manner. Here, we show that the calcium-dependent cytokines S100A8 and S100A9 are recruited to numerous promoters and enhancers in a model of breast cellular transformation. This recruitment is associated with multiple DNA sequence motifs recognized by DNA binding transcription factors that are linked to transcriptional activation and are important for transformation. The cytokines interact with these transcription factors in nuclear extracts, and they activate transcription when artificially recruited to a target promoter. Nuclear-specific expression of S100A8/A9 promotes oncogenic transcription and leads to enhanced breast transformation phenotype. These results suggest that, in addition to its classical cytokine function, S100A8/A9 can act as a transcriptional coactivator.

Immunohistochemical study of STAT3, HIF-1α and VEGF in pterygium and normal conjunctiva: Experimental research and literature review

Purpose

Signal transducer and activator of transcription 3 (STAT3) is a DNA-binding protein that regulates various biologic processes, including cell growth, apoptosis, and malignant transformation. Abnormal activation of STAT3 is associated with many diseases, and there is currently no relevant study on the pathogenesis of pterygium. The purpose of this study was to investigate the expression and clinical significance of STAT3, HIF-1α, and VEGF in pterygium at different stages.

Methods

Immunohistochemistry was used to study the expression levels of STAT3, HIF-1α, and VEGF in 50 cases of pterygium and 20 cases of control conjunctival tissue. The expression intensity of the three proteins was evaluated with Image-Pro Plus 6.0 image analysis software.

Results

In the pterygium group, the positive rates for STAT3, HIF-1α, and VEGF were 82.0%, 86.0%, and 84.0%, respectively, while those in the normal conjunctiva group were 40.0%, 25.0%, and 15.0%. The expression of STAT3, HIF-1α, and VEGF in pterygium was higher than that in control conjunctiva, and the expression in advanced pterygium was statistically significantly higher than that in stationary pterygium (p < 0.01). The expression levels of STAT3 and HIF-1α in pterygium were related to the length and depth of the corneal invasion of pterygium. The expression level of VEGF in pterygium was related to the length of pterygium, but not to the depth. In addition, there was a significant positive correlation between the expression of STAT3, HIF-1α, and VEGF (p < 0.01).

Conclusions

For the first time, the expression levels of the STAT3, HIF-1α, and VEGF proteins were detected simultaneously in pterygium tissue. Compared with normal conjunctiva, STAT3, HIF-1α, and VEGF were highly expressed in pterygium, and the expression in advanced pterygium tissue was more significant than in the stationary pterygium tissue. It is suggested that STAT3 may directly or through HIF-1α promote VEGF expression and participate in the growth and angiogenesis of pterygium. Targeting STAT3 may provide a new direction for the treatment of pterygium.

BCL9/STAT3 regulation of transcriptional enhancer networks promote DCIS progression

The molecular processes by which some human ductal carcinoma in situ (DCIS) lesions advance to the more aggressive form, while others remain indolent, are largely unknown. Experiments utilizing a patient-derived (PDX) DCIS Mouse INtraDuctal (MIND) animal model combined with ChIP-exo and RNA sequencing revealed that the formation of protein complexes between B Cell Lymphoma-9 (BCL9), phosphoserine 727 STAT3 (PS-727-STAT3) and non-STAT3 transcription factors on chromatin enhancers lead to subsequent transcription of key drivers of DCIS malignancy. Downregulation of two such targets, integrin β3 and its associated metalloproteinase, MMP16, resulted in a significant inhibition of DCIS invasive progression. Finally, in vivo targeting of BCL9, using rosemary extract, resulted in significant inhibition of DCIS malignancy in both cell line and PDX DCIS MIND animal models. As such, our studies provide compelling evidence for future testing of rosemary extract as a chemopreventive agent in breast cancer.

Bladder neoplasms and NF-κB: an unfathomed association

Introduction: Bladder cancer is the second most common genitourinary tract cancer and is often recurrent and/or chemoresistant after tumor resection. Cigarette smoking, exposure to aromatic amines, and chronic infection/inflammation are bladder cancer risk factors. NF-κB is a transcription factor that plays a critical role in normal physiology and bladder cancer. Bladder cancer patients have constitutively active NF-κB triggered by pro-inflammatory cytokines, chemokines, and hypoxia, augmenting carcinogenesis and progression.Areas covered: NF-κB orchestrates protein interactions (PTEN, survivin, VEGF), regulation (CYLD, USP13) and gene expression (Trp 53) resulting in bladder cancer progression, recurrence and resistance to therapy. This review focuses on NF-κB in bladder inflammation, cancer and resistance to therapy.Expert opinion: NF-κB and bladder cancer necessitate further research to develop better diagnostic and treatment regimens that address progression, recurrence and resistance to therapy. NF-κB is a master regulator that can act with or on minimally one cancer hallmark gene or protein, leading to bladder cancer progression (Tp53, PTEN, VEGF, HMGB1, CYLD, USP13), recurrence (PCNA, BcL-2, JUN) and resistance to therapy (P-gp, twist, SETD6). Thus, an understanding of bladder cancer in relation to NF-κB will offer improved strategies and efficacious targeted therapies resulting in minimal progression, recurrence and resistance to therapy.

Stable intronic sequence RNAs (sisRNAs) are selected regions in introns with distinct properties

Background

Stable introns and intronic fragments make up the largest population of RNA in the oocyte nucleus of the frog Xenopus tropicalis. These stable intronic sequence RNAs (sisRNAs) persist through the onset of zygotic transcription when synchronous cell division has ended, and the developing embryo consists of approximately 8000 cells. Despite their abundance, the sequence properties and biological function of sisRNAs are just beginning to be understood.

Results

To characterize this population of non-coding RNA, we identified all of the sisRNAs in the X. tropicalis oocyte nucleus using published high-throughput RNA sequencing data. Our analysis revealed that sisRNAs, have an average length of ~ 360 nt, are widely expressed from genes with multiple introns, and are derived from specific regions of introns that are GC and TG rich, while CpG poor. They are enriched in introns at both ends of transcripts but preferentially at the 3′ end. The consensus binding sites of specific transcription factors such as Stat3 are enriched in sisRNAs, suggesting an association between sisRNAs and transcription factors involved in early development. Evolutionary conservation analysis of sisRNA sequences in seven vertebrate genomes indicates that sisRNAs are as conserved as other parts of introns, but much less conserved than exons.

Conclusion

In total, our results indicate sisRNAs are selected intron regions with distinct properties and may play a role in gene expression regulation.

Fine-mapping of a novel premenopausal breast cancer susceptibility locus at Chr4q31.22 in Caucasian women and validation in African and Chinese women

We previously identified a novel breast cancer susceptibility variant on chromosome 4q31.22 locus (rs1429142) conferring risk among women of European ancestry. Here, we report replication of findings, validation of the variant in diverse populations and fine-mapping of the associated locus in Caucasian population. The SNP rs1429142 (C/T, minor allele frequency 18%) showed association for the overall breast cancer risk in Stages 1-4 (n = 4,331 cases/4271 controls; p = 4.35 × 10-8 ; odds ratio, ORC-allele ,1.25), and an elevated risk among premenopausal women (n = 1,503 cases/4271 controls; p = 5.81 × 10-10 ; ORC-allele 1.40) in European populations. SNP rs1429142 was associated with premenopausal breast cancer risk in women of African (T/C; p-value 1.45 × 10-02 ; ORC-allele 1.2) but not from Chinese ancestry. Fine-mapping of the locus revealed several potential causal variants which are present within a single association signal, revealed from the conditional regression analysis. Functional annotation of the potential causal variants revealed three putative SNPs rs1366691, rs1429139 and rs7667633 with active enhancer functions inferred based on histone marks, DNase hypersensitive sites in breast cell line data. These putative variants were bound by transcription factors (C-FOS, STAT1/3 and POL2/3) with known roles in inflammatory pathways. Furthermore, Hi-C data revealed several short-range interactions in the fine-mapped locus harboring the putative variants. The fine mapped locus was predicted to be within a single topologically associated domain, potentially facilitating enhancer-promoter interactions possibly leading to the regulation of nearby genes.

Targeting STAT3 and STAT5 in Tumor-Associated Immune Cells to Improve Immunotherapy

Oncogene-induced STAT3-activation is central to tumor progression by promoting cancer cell expression of pro-angiogenic and immunosuppressive factors. STAT3 is also activated in infiltrating immune cells including tumor-associated macrophages (TAM) amplifying immune suppression. Consequently, STAT3 is considered as a target for cancer therapy. However, its interplay with other STAT-family members or transcription factors such as NF-κB has to be considered in light of their concerted regulation of immune-related genes. Here, we discuss new attempts at re-educating immune suppressive tumor-associated macrophages towards a CD8 T cell supporting profile, with an emphasis on the role of STAT transcription factors on TAM functional programs. Recent clinical trials using JAK/STAT inhibitors highlighted the negative effects of these molecules on the maintenance and function of effector/memory T cells. Concerted regulation of STAT3 and STAT5 activation in CD8 T effector and memory cells has been shown to impact their tumor-specific responses including intra-tumor accumulation, long-term survival, cytotoxic activity and resistance toward tumor-derived immune suppression. Interestingly, as an escape mechanism, melanoma cells were reported to impede STAT5 nuclear translocation in both CD8 T cells and NK cells. Ours and others results will be discussed in the perspective of new developments in engineered T cell-based adoptive therapies to treat cancer patients.

Inflammatory pathway interactions and cancer multidrug resistance regulation

Multidrug resistances against chemotherapeutics are among the major challenges related to cancer treatment. Recent studies have demonstrated that different conditions may tune the expression and activity of MDR transporters. For instance, inflammation occurs through a complex cytological process and chemical reactions in the most tumor microenvironment; it can play a critical role in cancer development and is capable of altering the expression and function of MDR transporters. Cytokines, interleukins, and prostaglandins are potent inflammatory mediators that can modulate the expression of MDRs at transcriptional and post-transcriptional levels in the most human cancer cells and tissues and potentially contribute to balance bioavailability of chemotherapeutic agents. Since cancer cases are usually accompanied by inflammatory responses, glucocorticoids and NSAIDs are the primary useful combination chemotherapies in a variety of cancer treatment protocols. In addition to the anti-inflammatory activities of these agents, they exert diverse modulatory effects on MDR-mediated drug resistance via specific mechanisms. Several factors, including cell and MDR-protein types, pharmacokinetics, and pharmacogenetics, mainly influence the regulatory mechanisms. Uncovering the networks between inflammation and multidrug resistance will be clinically helpful in the treatment of malignant cancers and decreasing the cancer mortality rates.

Satb1 integrates DNA binding site geometry and torsional stress to differentially target nucleosome-dense regions

The Satb1 genome organizer regulates multiple cellular and developmental processes. It is not yet clear how Satb1 selects different sets of targets throughout the genome. Here we have used live-cell single molecule imaging and deep sequencing to assess determinants of Satb1 binding-site selectivity. We have found that Satb1 preferentially targets nucleosome-dense regions and can directly bind consensus motifs within nucleosomes. Some genomic regions harbor multiple, regularly spaced Satb1 binding motifs (typical separation ~1 turn of the DNA helix) characterized by highly cooperative binding. The Satb1 homeodomain is dispensable for high affinity binding but is essential for specificity. Finally, we find that Satb1-DNA interactions are mechanosensitive. Increasing negative torsional stress in DNA enhances Satb1 binding and Satb1 stabilizes base unpairing regions against melting by molecular machines. The ability of Satb1 to control diverse biological programs may reflect its ability to combinatorially use multiple site selection criteria.

Inflammatory regulatory network mediated by the joint action of NF-kB, STAT3, and AP-1 factors is involved in many human cancers

Using an inducible, inflammatory model of breast cellular transformation, we describe the transcriptional regulatory network mediated by STAT3, NF-κB, and AP-1 factors on a genomic scale. These proinflammatory regulators form transcriptional complexes that directly regulate the expression of hundreds of genes in oncogenic pathways via a positive feedback loop. This transcriptional feedback loop and associated network functions to various extents in many types of cancer cells and patient tumors, and it is the basis for a cancer inflammation index that defines cancer types by functional criteria. We identify a network of noninflammatory genes whose expression is well correlated with the cancer inflammatory index. Conversely, the cancer inflammation index is negatively correlated with the expression of genes involved in DNA metabolism, and transformation is associated with genome instability. We identify drugs whose efficacy in cell lines is correlated with the cancer inflammation index, suggesting the possibility of using this index for personalized cancer therapy. Inflammatory tumors are preferentially associated with infiltrating immune cells that might be recruited to the site of the tumor via inflammatory molecules produced by the cancer cells.

The ASD Living Biology: from cell proliferation to clinical phenotype

Autism spectrum disorder (ASD) has captured the attention of scientists, clinicians and the lay public because of its uncertain origins and striking and unexplained clinical heterogeneity. Here we review genetic, genomic, cellular, postmortem, animal model, and cell model evidence that shows ASD begins in the womb. This evidence leads to a new theory that ASD is a multistage, progressive disorder of brain development, spanning nearly all of prenatal life. ASD can begin as early as the 1st and 2nd trimester with disruption of cell proliferation and differentiation. It continues with disruption of neural migration, laminar disorganization, altered neuron maturation and neurite outgrowth, disruption of synaptogenesis and reduced neural network functioning. Among the most commonly reported high-confidence ASD (hcASD) genes, 94% express during prenatal life and affect these fetal processes in neocortex, amygdala, hippocampus, striatum and cerebellum. A majority of hcASD genes are pleiotropic, and affect proliferation/differentiation and/or synapse development. Proliferation and subsequent fetal stages can also be disrupted by maternal immune activation in the 1st trimester. Commonly implicated pathways, PI3K/AKT and RAS/ERK, are also pleiotropic and affect multiple fetal processes from proliferation through synapse and neural functional development. In different ASD individuals, variation in how and when these pleiotropic pathways are dysregulated, will lead to different, even opposing effects, producing prenatal as well as later neural and clinical heterogeneity. Thus, the pathogenesis of ASD is not set at one point in time and does not reside in one process, but rather is a cascade of prenatal pathogenic processes in the vast majority of ASD toddlers. Despite this new knowledge and theory that ASD biology begins in the womb, current research methods have not provided individualized information: What are the fetal processes and early-age molecular and cellular differences that underlie ASD in each individual child? Without such individualized knowledge, rapid advances in biological-based diagnostic, prognostic, and precision medicine treatments cannot occur. Missing, therefore, is what we call ASD Living Biology. This is a conceptual and paradigm shift towards a focus on the abnormal prenatal processes underlying ASD within each living individual. The concept emphasizes the specific need for foundational knowledge of a living child's development from abnormal prenatal beginnings to early clinical stages. The ASD Living Biology paradigm seeks this knowledge by linking genetic and in vitro prenatal molecular, cellular and neural measurements with in vivo post-natal molecular, neural and clinical presentation and progression in each ASD child. We review the first such study, which confirms the multistage fetal nature of ASD and provides the first in vitro fetal-stage explanation for in vivo early brain overgrowth. Within-child ASD Living Biology is a novel research concept we coin here that advocates the integration of in vitro prenatal and in vivo early post-natal information to generate individualized and group-level explanations, clinically useful prognoses, and precision medicine approaches that are truly beneficial for the individual infant and toddler with ASD.

Risk Locus Identification Ties Alcohol Withdrawal Symptoms to SORCS2

BACKGROUND

Efforts to promote the cessation of harmful alcohol use are hindered by the affective and physiological components of alcohol withdrawal (AW), which can include life-threatening seizures. Although previous studies of AW and relapse have highlighted the detrimental role of stress, little is known about genetic risk factors.

METHODS

We conducted a genome-wide association study of AW symptom count in uniformly assessed subjects with histories of serious AW, followed by additional genotyping in independent AW subjects.

RESULTS

The top association signal for AW severity was in sortilin family neurotrophin receptor gene SORCS2 on chromosome 4 (European American meta-analysis n = 1,478, p = 4.3 × 10-9 ). There were no genome-wide significant findings in African Americans (n = 1,231). Bioinformatic analyses were conducted using publicly available high-throughput transcriptomic and epigenomic data sets, showing that in humans SORCS2 is most highly expressed in the nervous system. The identified SORCS2 risk haplotype is predicted to disrupt a stress hormone-modulated regulatory element that has tissue-specific activity in human hippocampus. We used human neural lineage cells to demonstrate in vitro a causal relationship between stress hormone levels and SORCS2 expression, and show that SORCS2 levels in culture are increased upon ethanol exposure and withdrawal.

CONCLUSIONS

Taken together, these findings indicate that the pathophysiology of withdrawal may involve the effects of stress hormones on neurotrophic factor signaling. Further investigation of these pathways could produce new approaches to managing the aversive consequences of abrupt alcohol cessation.

IL1-Induced JAK/STAT Signaling Is Antagonized by TGFβ to Shape CAF Heterogeneity in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is poorly responsive to therapies and histologically contains a paucity of neoplastic cells embedded within a dense desmoplastic stroma. Within the stroma, cancer-associated fibroblasts (CAF) secrete tropic factors and extracellular matrix components, and have been implicated in PDAC progression and chemotherapy resistance. We recently identified two distinct CAF subtypes characterized by either myofibroblastic or inflammatory phenotypes; however, the mechanisms underlying their diversity and their roles in PDAC remain unknown. Here, we use organoid and mouse models to identify TGFβ and IL1 as tumor-secreted ligands that promote CAF heterogeneity. We show that IL1 induces LIF expression and downstream JAK/STAT activation to generate inflammatory CAFs and demonstrate that TGFβ antagonizes this process by downregulating IL1R1 expression and promoting differentiation into myofibroblasts. Our results provide a mechanism through which distinct fibroblast niches are established in the PDAC microenvironment and illuminate strategies to selectively target CAFs that support tumor growth. SIGNIFICANCE: Understanding the mechanisms that determine CAF heterogeneity in PDAC is a prerequisite for the rational development of approaches that selectively target tumor-promoting CAFs. Here, we identify an IL1-induced signaling cascade that leads to JAK/STAT activation and promotes an inflammatory CAF state, suggesting multiple strategies to target these cells in vivo. See related commentary by Ling and Chiao, p. 173. This article is highlighted in the In This Issue feature, p. 151.

IL-6 augments IL-4-induced polarization of primary human macrophages through synergy of STAT3, STAT6 and BATF transcription factors

Macrophages in the tumor microenvironment respond to complex cytokine signals. How these responses shape the phenotype of tumor-associated macrophages (TAMs) is incompletely understood. Here we explored how cytokines of the tumor milieu, interleukin (IL)-6 and IL-4, interact to influence target gene expression in primary human monocyte-derived macrophages (hMDMs). We show that dual stimulation with IL-4 and IL-6 synergistically modified gene expression. Among the synergistically induced genes are several targets with known pro-tumorigenic properties, such as CC-chemokine ligand 18 (CCL18), transforming growth factor alpha (TGFA) or CD274 (programmed cell death 1 ligand 1 (PD-L1)). We found that transcription factors of the signal transducer and activator of transcription (STAT) family, STAT3 and STAT6 bind regulatory regions of synergistically induced genes in close vicinity. STAT3 and STAT6 co-binding further induces the basic leucine zipper ATF-like transcription factor (BATF), which participates in synergistic induction of target gene expression. Functional analyses revealed increased MCF-7 and MDA-MB 231 tumor cell motility in response to conditioned media from co-treated hMDMs compared to cells incubated with media from single cytokine-treated hMDMs. Flow cytometric analysis of T cell populations upon co-culture with hMDMs polarized by different cytokines indicated that dual stimulation promoted immunosuppressive properties of hMDMs in a PD-L1-dependent manner. Analysis of clinical data revealed increased expression of BATF together with TAM markers in tumor stroma of breast cancer patients as compared to normal breast tissue stroma. Collectively, our findings suggest that IL-4 and IL-6 cooperate to alter the human macrophage transcriptome, endowing hMDMs with pro-tumorigenic properties.

Genome-scale identification of transcription factors that mediate an inflammatory network during breast cellular transformation

Transient activation of Src oncoprotein in non-transformed, breast epithelial cells can initiate an epigenetic switch to the stably transformed state via a positive feedback loop that involves the inflammatory transcription factors STAT3 and NF-κB. Here, we develop an experimental and computational pipeline that includes 1) a Bayesian network model (AccessTF) that accurately predicts protein-bound DNA sequence motifs based on chromatin accessibility, and 2) a scoring system (TFScore) that rank-orders transcription factors as candidates for being important for a biological process. Genetic experiments validate TFScore and suggest that more than 40 transcription factors contribute to the oncogenic state in this model. Interestingly, individual depletion of several of these factors results in similar transcriptional profiles, indicating that a complex and interconnected transcriptional network promotes a stable oncogenic state. The combined experimental and computational pipeline represents a general approach to comprehensively identify transcriptional regulators important for a biological process.

LINC00520 is induced by Src, STAT3, and PI3K and plays a functional role in breast cancer

Long non-coding RNAs (lncRNAs) have been implicated in normal cellular homeostasis as well as pathophysiological conditions, including cancer. Here we performed global gene expression profiling of mammary epithelial cells transformed by oncogenic v-Src, and identified a large subset of uncharacterized lncRNAs potentially involved in breast cancer development. Specifically, our analysis revealed a novel lncRNA, LINC00520 that is upregulated upon ectopic expression of oncogenic v-Src, in a manner that is dependent on the transcription factor STAT3. Similarly, LINC00520 is also increased in mammary epithelial cells transformed by oncogenic PI3K and its expression is decreased upon knockdown of mutant PIK3CA. Additional expression profiling highlight that LINC00520 is elevated in a subset of human breast carcinomas, with preferential enrichment in the basal-like molecular subtype. ShRNA-mediated depletion of LINC00520 results in decreased cell migration and loss of invasive structures in 3D. RNA sequencing analysis uncovers several genes that are differentially expressed upon ectopic expression of LINC00520, a significant subset of which are also induced in v-Src-transformed MCF10A cells. Together, these findings characterize LINC00520 as a lncRNA that is regulated by oncogenic Src, PIK3CA and STAT3, and which may contribute to the molecular etiology of breast cancer.

Heterochromatin Reduction Correlates with the Increase of the KDM4B and KDM6A Demethylases and the Expression of Pericentromeric DNA during the Acquisition of a Transformed Phenotype

Cancer cells have alterations in chromatin organization, mostly a reduction in heterochromatin. How this process occurs during transformation and if it participates in the maintenance of a cancerous phenotype is not well understood. Here, using a transformation-inducible cell line, we analyzed the changes that occur in heterochromatin during transformation to a cancerous phenotype. After transformation, there is a reduction in heterochromatin bodies and a nuclear reorganization of HP1α. These occurrences correlate with reductions in H3K9me3 and H3K27me3 levels and with some of the enzymes that introduce these modifications. At the same time, there are increases in the KDM4B and KDM6A/UTX demethylases and an enhancement in the transcription of pericentromeric DNA that correlate with the reduction of H3K9me3 and the recruitment of KDM4B to these elements. The depletion of KDM4B and KDM6A/UTX has a more deleterious effect in transformed cells than in their progenitors, suggesting an important role for these enzymes in the survival of cancerous cells. These results provide new insights into heterochromatin dynamics during transformation to a cancerous phenotype as well as some of the participating mechanisms.

Cancer is an adaptation that selects in animals against energy dissipation

As cancer usually follows reproduction, it is generally assumed that cancer does not select. Graham has however argued that juvenile cancer, which precedes reproduction, could during evolution have implemented a "cancer selection" that resulted in novel traits that suppress this juvenile cancer; an example is protection against UV sunlight-induced cancer, required for the emergence of terrestrial animals from the sea. We modify the cancer selection mechanism to the posited "cancer adaptation" mechanism, in which juvenile mortality is enhanced through the diminished care received by juveniles from their (grand) parents when these suffer from cancer in old age. Moreover, it is posited that the cancer adaptation selects against germline "dissipative genes", genes that result in enhanced free energy dissipation. Cancer's progression is interpreted as a cascade at increasing scale of repeated amplification of energy dissipation, a cascade involving heat shock, the Warburg effect, the cytokine IL-6, tumours, and hypermetabolism. Disturbance of any physiological process must enhance energy dissipation if the animal remains functioning normally, what explains multicausality, why "everything gives you cancer". The hypothesis thus comprises two newly invoked partial processes-diminished (grand) parental care and dissipation amplification-and results in a "selection against enhanced energy dissipation" which gives during evolution the benefit of energy conservation. Due to this benefit, cancer would essentially be an adaptation, and not a genetic disease, as assumed in the "somatic mutation theory". Cancer by somatic mutations is only a side process. The cancer adaptation hypothesis is substantiated by (1) cancer's extancy, (2) the failure of the somatic mutation theory, (3) cancer's initiation by a high temperature, (4) the interpretation of cancer's progression as a thermal process, and (5) the interpretation of tumours as organs that implement thermogenesis. The hypothesis could in principle be verified by monitoring in a population over several generations (1) the presence of dissipative genes, (2) the incidence of cancer, and (3) the beneficial effect of dissipative gene removal by cancer on starvation/famine survival.

Stat3 is a candidate epigenetic biomarker of perinatal Bisphenol A exposure associated with murine hepatic tumors with implications for human health

Bisphenol A (BPA) is an endocrine disrupting chemical (EDC) that has been implicated as a potential carcinogen and epigenotoxicant. We have previously reported dose-dependent incidence of hepatic tumors in 10-month-old isogenic mice perinatally exposed to BPA. Here, we evaluated DNA methylation at 3 candidate genes (Esr1, Il-6st, and Stat3) in liver tissue of BPA-exposed mice euthanized at 2 time points: post-natal day 22 (PND22; n = 147) or 10-months of age (n = 78, including n = 18 with hepatic tumors). Additionally, DNA methylation profiles were analyzed at human homologs of murine candidate genes in human fetal liver samples (n = 50) with known liver tissue BPA levels. Candidate genes were chosen based on reported expression changes in both rodent and human hepatocellular carcinoma (HCC). Regions for bisulfite sequencing were chosen by mining whole genome next generation sequencing methylation datasets of both mice and human liver samples with known perinatal BPA exposures. One of 3 candidate genes, Stat3, displayed dose-dependent DNA methylation changes in both 10-month mice with liver tumors as compared to those without liver tumors and 3-week sibling mice from the same exposure study, implicating Stat3 as a potential epigenetic biomarker of both early life BPA exposure and adult disease in mice. DNA methylation profiles within STAT3 varied with liver tissue BPA level in human fetal liver samples as well, suggesting STAT3 may be a translationally relevant candidate biomarker. These data implicate Stat3 as a potential early life biomarker of adult murine liver tumor risk following early BPA exposure with early evidence of relevance to human health.

STAT3 in the systemic inflammation of cancer cachexia

Weight loss is diagnostic of cachexia, a debilitating syndrome contributing mightily to morbidity and mortality in cancer. Most research has probed mechanisms leading to muscle atrophy and adipose wasting in cachexia; however cachexia is a truly systemic phenomenon. Presence of the tumor elicits an inflammatory response and profound metabolic derangements involving not only muscle and fat, but also the hypothalamus, liver, heart, blood, spleen and likely other organs. This global response is orchestrated in part through circulating cytokines that rise in conditions of cachexia. Exogenous Interleukin-6 (IL6) and related cytokines can induce most cachexia symptomatology, including muscle and fat wasting, the acute phase response and anemia, while IL-6 inhibition reduces muscle loss in cancer. Although mechanistic studies are ongoing, certain of these cachexia phenotypes have been causally linked to the cytokine-activated transcription factor, STAT3, including skeletal muscle wasting, cardiac dysfunction and hypothalamic inflammation. Correlative studies implicate STAT3 in fat wasting and the acute phase response in cancer cachexia. Parallel data in non-cancer models and disease states suggest both pathological and protective functions for STAT3 in other organs during cachexia. STAT3 also contributes to cancer cachexia through enhancing tumorigenesis, metastasis and immune suppression, particularly in tumors associated with high prevalence of cachexia. This review examines the evidence linking STAT3 to multi-organ manifestations of cachexia and the potential and perils for targeting STAT3 to reduce cachexia and prolong survival in cancer patients.

Hsp90 as a "Chaperone" of the Epigenome: Insights and Opportunities for Cancer Therapy

The cellular functions of Hsp90 have historically been attributed to its ability to chaperone client proteins involved in signal transduction. Although numerous stimuli and the signaling cascades they activate contribute to cancer progression, many of these pathways ultimately require transcriptional effectors to elicit tumor-promoting effects. Despite this obvious connection, the majority of studies evaluating Hsp90 function in malignancy have focused upon its regulation of cytosolic client proteins, and particularly members of receptor and/or kinase families. However, in recent years, Hsp90 has emerged as a pivotal orchestrator of nuclear events. Discovery of an expanding repertoire of Hsp90 clients has illuminated a vital role for Hsp90 in overseeing nuclear events and influencing gene transcription. Hence, this chapter will cast a spotlight upon several regulatory themes involving Hsp90-dependent nuclear functions. Highlighted topics include a summary of chaperone-dependent regulation of key transcription factors (TFs) and epigenetic effectors in malignancy, as well as a discussion of how the complex interplay among a subset of these TFs and epigenetic regulators may generate feed-forward loops that further support cancer progression. This chapter will also highlight less recognized indirect mechanisms whereby Hsp90-supported signaling may impinge upon epigenetic regulation. Finally, the relevance of these nuclear events is discussed within the framework of Hsp90's capacity to enable phenotypic variation and drug resistance. These newly acquired insights expanding our understanding of Hsp90 function support the collective notion that nuclear clients are major beneficiaries of Hsp90 action, and their impairment is likely responsible for many of the anticancer effects elicited by Hsp90-targeted approaches.