The inflammatory/cancer-related IL-6/STAT3/NF-κB positive feedback loop includes AUF1 and maintains the active state of breast myofibroblasts

Interleukin-2 induces extracellular matrix synthesis and TGF-β2 expression in retinal pigment epithelial cells

Macular fibrosis is a vital obstacle of vision acuity improvement of age‐related macular degeneration patients. This study was to investigate the effects of interleukin 2 (IL‐2) on epithelial‐mesenchymal transition (EMT), extracellular matrix (ECM) synthesis and transforming growth factor β2 (TGF‐β2) expression in retinal pigment epithelial (RPE) cells. 10 μg/L IL‐2 was used to induce fibrosis in RPE cells for various times. Western blot was used to detect the EMT marker α‐smooth muscle actin (α‐SMA), ECM markers fibronectin (Fn) and type 1 collagen (COL‐1), TGF‐β2, and the activation of the JAK/STAT3 and NF‐κB signaling pathway. Furthermore, JAK/STAT3 and NF‐κB signaling pathways were specifically blocked by WP1066 or BAY11‐7082, respectively, and the expression of α‐SMA, COL‐1, Fn and TGF‐β2 protein were detected. Wound healing and Transwell assays were used to measure cell migration ability of IL‐2 with or without WP1066 or BAY11‐7082. After induction of IL‐2, the expressions of Fn, COL‐1, TGF‐β2 protein were significantly increased, and this effect was correlated with IL‐2 treatment duration, while α‐SMA protein expression did not change significantly. Both WP1066 and BAY11‐7082 could effectively downregulate the expression of Fn, COL‐1 and TGF‐β2 induced by IL‐2. What's more, both NF‐κB and JAK/STAT3 inhibitors could suppress the activation of the other signaling pathway. Additionally, JAK/STAT3 inhibitor WP1066 and NF‐κB inhibitor BAY 11‐7082 could obviously decrease RPE cells migration capability induced by IL‐2. IL‐2 promotes cell migration, ECM synthesis and TGF‐β2 expression in RPE cells via JAK/STAT3 and NF‐κB signaling pathways, which may play an important role in proliferative vitreoretinopathy.

Modulation of glioma-inflammation crosstalk profiles in human glioblastoma cells by indirubin-3'-(2,3 dihydroxypropyl)-oximether (E804) and 7-bromoindirubin-3'-oxime (7BIO)

Indirubins E804 (indirubin-3'-(2,3 dihydroxypropyl)-oximether) and 7BIO (7-Bromoindirubin-3'-oxime) are synthetic derivatives of natural indirubin, the active compound in Danggui Longhui Wan, a traditional Chinese remedy for cancer and inflammation. Herein, we explore E804 and 7BIO for their potential to modulate key pro-inflammatory genes and cytokines in LN-18 and T98G glioblastoma cells. High grade gliomas typically secrete large amounts of inflammatory cytokines and growth factors that promote tumor growth in an autocrine fashion. Inflammation is emerging as a key concern in the success of new treatment modalities for glioblastomas. Studies indicate that select indirubin derivatives bind and activate signaling of the AHR pathway, as well as inhibit cyclin-dependent kinases and STAT3 signaling. AHR signaling is involved in hematopoiesis, immune function, cell cycling, and inflammation, and thus may be a possible target for glioma treatment. To determine the significance of the AHR pathway in LN-18 and T98G glioma inflammatory profiles, and on the effects of E804 and 7BIO on these profiles, we used 6,2',4'-trimethoxyflavone (TMF), a putative selective AHR antagonist. It was confirmed that E804 and 7BIO activates the AHR leading to cyp1b1 expression, and that TMF antagonizes expression. We then employed a commercial cancer inflammation and immunity crosstalk qRT-PCR array to screen for anti-inflammatory related properties. TMF alone inhibited expression of ifng, ptsg2, il12b, tnfa, il10, il13, the balance between pd1 and pdl1, and even expression of mhc1a/b. E804 was very potent in suppressing many pro-inflammatory genes, including il1a, il1b, il12a, ptgs2, tlr4, and others. E804 also affected expression of il6, vegfa, and stat3. Conversely, 7BIO induced cox2, but suppressed a different selection of pro-inflammatory genes including nos2, tnfa, and igf1. Secretion of IL-6 protein, an iconic inflammatory cytokine, was decreased by E804. VEGF (vascular endothelial growth factor) protein secretion was upregulated by 7BIO, yet downregulated by E804 and E804 plus TMF. Thus, E804 is both an AHR ligand and regulator of important pro-inflammatory cytokines such as IL-6 and oncogene STAT3, among others. Our results point to the use of E804 and TMF in combination as a promising new treatment for glioblastoma.

Autocrine TGF-β1/miR-200s/miR-221/DNMT3B regulatory loop maintains CAF status to fuel breast cancer cell proliferation

Cancer-associated fibroblasts (CAFs) remain active even in the absence of cancer cells. However, the molecular mechanism underlying the sustained active status of CAFs is largely unrevealed. We found that in CAFs, DNMT3B was not only a target of miR-200b, miR-200c and miR-221, but was able to induce DNA methylation of miR-200s promoters. DNMT3B eventually reached a stably high level by the counteracting effect of decreasing miR-200b/c and increasing miR-221 in normal fibroblasts (NFs) with long-term exogenous TGF-β1 treatment, and DNMT3B further led to a low level of miR-200s which established CAF activation. Meanwhile, miR-200s/miR-221/DNMT3B signaling sustained autocrine TGF-β1 maintaining active CAF status. Destruction of the autocrine TGF-β1/miR-200s/miR-221/DNMT3B signaling led to demethylation of miR-200s promoters and further restored the NF phenotypes. Moreover, we confirmed that TCF12, the target of miR-141, stimulated c-Myc/Cyclin D1 axis in breast cancer cells to promote cancer growth by enhancing CXCL12 of CAFs. The current study reveals that the TGF-β1/miR-200s/miR-221/DNMT3B regulatory loop is responsible for the maintenance of CAFs status and is also necessary for CAF function in promoting malignance of breast cancer, which provides a potential target for CAF-driven therapeutic strategy.

Genomic Signatures Predict the Immunogenicity of BRCA-Deficient Breast Cancer

PURPOSE

Breast cancers with BRCA1/2 alterations have a relatively high mutational load, suggesting that immune checkpoint blockade may be a potential treatment option. However, the degree of immune cell infiltration varies widely, and molecular features contributing to this variability remain unknown.

EXPERIMENTAL DESIGN

We hypothesized that genomic signatures might predict immunogenicity in BRCA1/2 breast cancers. Using The Cancer Genome Atlas (TCGA) genomic data, we compared breast cancers with (89) and without (770) either germline or somatic BRCA1/2 alterations. We also studied 35 breast cancers with germline BRCA1/2 mutations from Penn using WES and IHC.

RESULTS

We found that homologous recombination deficiency (HRD) scores were negatively associated with expression-based immune indices [cytolytic index (P = 0.04), immune ESTIMATE (P = 0.002), type II IFN signaling (P = 0.002)] despite being associated with a higher mutational/neoantigen burden, in BRCA1/2 mutant breast cancers. Further, absence of allele-specific loss of heterozygosity (LOH negative; P = 0.01) or subclonality (P = 0.003) of germline and somatic BRCA1/2 mutations, respectively, predicted for heightened cytolytic activity. Gene set analysis found that multiple innate and adaptive immune pathways that converge on NF-κB may contribute to this heightened immunogenicity. IHC of Penn breast cancers demonstrated increased CD45⁺ (P = 0.039) and CD8⁺ infiltrates (P = 0.037) and increased PDL1 expression (P = 0.012) in HRD-low or LOH-negative cancers. Triple-negative cancers with low HRD had far greater CD8⁺ T cells (P = 0.0011) and Perforin 1 expression (P = 0.014) compared with hormone receptor-positive HRD-high cancers.

CONCLUSIONS

HRD scores and hormone receptor subtype are predictive of immunogenicity in BRCA1/2 breast cancers and may inform the design of optimal immune therapeutic strategies.

Downregulation of Pro-Inflammatory and Pro-Angiogenic Pathways in Prostate Cancer Cells by a Polyphenol-Rich Extract from Olive Mill Wastewater

Dietary phytochemicals are particularly attractive for chemoprevention and are able to modulate several signal transduction pathways linked with cancer. Olive oil, a major component of the Mediterranean diet, is an abundant source of phenolic compounds. Olive oil production is associated with the generation of a waste material, termed 'olive mill wastewater' (OMWW) that have been reported to contain water-soluble polyphenols. Prostate cancer (PCa) is considered as an ideal cancer type for chemopreventive approaches, due to its wide incidence but relatively long latency period and progression time. Here, we investigated activities associated with potential preventive properties of a polyphenol-rich olive mill wastewater extract, OMWW (A009), on three in vitro models of PCa. A009 was able to inhibit PCa cell proliferation, adhesion, migration, and invasion. Molecularly, we found that A009 targeted NF-κB and reduced pro-angiogenic growth factor, VEGF, CXCL8, and CXCL12 production. IL-6/STAT3 axis was also regulated by the extract. A009 shows promising properties, and purified hydroxytyrosol (HyT), the major polyphenol component of A009, was also active but not always as effective as A009. Finally, our results support the idea of repositioning a food waste-derived material for nutraceutical employment, with environmental and industrial cost management benefits.

Interactions between cancer-associated fibroblasts and tumor cells promote MCL-1 dependency in estrogen receptor-positive breast cancers

Selective inhibition of BCL-2 is expected to enhance therapeutic vulnerability in luminal estrogen receptor-positive breast cancers. We show here that the BCL-2 dependency of luminal tumor cells is nevertheless mitigated by breast cancer-associated fibroblasts (bCAFs) in a manner that defines MCL-1 as another critical therapeutic target. bCAFs favor MCL-1 expression and apoptotic resistance in luminal cancer cells in a IL-6 dependent manner while their own, robust, survival also relies on MCL-1. Studies based on ex vivo cultures of human luminal breast cancer tissues further argue that the contribution of stroma-derived signals to MCL-1 expression shapes BCL-2 dependency. Thus, MCL-1 inhibitors are beneficial for targeted apoptosis of breast tumor ecosystems, even in a subtype where MCL-1 dependency is not intrinsically driven by oncogenic pathways.

Interleukin-6 Interweaves the Bone Marrow Microenvironment, Bone Loss, and Multiple Myeloma

The immune system is strongly linked to the maintenance of healthy bone. Inflammatory cytokines, specifically, are crucial to skeletal homeostasis and any dysregulation can result in detrimental health complications. Interleukins, such as interleukin 6 (IL-6), act as osteoclast differentiation modulators and as such, must be carefully monitored and regulated. IL-6 encourages osteoclastogenesis when bound to progenitors and can cause excessive osteoclastic activity and osteolysis when overly abundant. Numerous bone diseases are tied to IL-6 overexpression, including rheumatoid arthritis, osteoporosis, and bone-metastatic cancers. In the latter, IL-6 can be released with growth factors into the bone marrow microenvironment (BMM) during osteolysis from bone matrix or from cancer cells and osteoblasts in an inflammatory response to cancer cells. Thus, IL-6 helps create an ideal microenvironment for oncogenesis and metastasis. Multiple myeloma (MM) is a blood cancer that homes to the BMM and is strongly tied to overexpression of IL-6 and bone loss. The roles of IL-6 in the progression of MM are discussed in this review, including roles in bone homing, cancer-associated bone loss, disease progression and drug resistance. MM disease progression often includes the development of drug-resistant clones, and patients commonly struggle with reoccurrence. As such, therapeutics that specifically target the microenvironment, rather than the cancer itself, are ideal and IL-6, and its myriad of downstream signaling partners, are model targets. Lastly, current and potential therapeutic interventions involving IL-6 and connected signaling molecules are discussed in this review.

Interleukin-8 Activates Breast Cancer-Associated Adipocytes and Promotes Their Angiogenesis- and Tumorigenesis-Promoting Effects

Increasing evidence supports the critical role of active stromal adipocytes in breast cancer development and spread. However, the mediators and the mechanisms of action are still elusive. We show here that cancer-associated adipocytes (CAAs) isolated from 10 invasive breast carcinomas are proinflammatory and exhibit active phenotypes, including higher proliferative, invasive, and migratory capacities compared to their adjacent tumor-counterpart adipocytes (TCAs). Furthermore, all CAAs secreted higher level of interleukin-8 (IL-8), which is critical in mediating the paracrine procarcinogenic effects of these cells. Importantly, ectopic expression of IL-8 in TCA cells activated them and enhanced their procarcinogenic effects both in vitro, in a STAT3-dependent manner, and in vivo In contrast, inhibition of the IL-8 signaling using specific short hairpin RNA, anti-IL-8 antibody, or reparixin suppressed the active features of CAAs, including their non-cell-autonomous tumor-promoting activities both on breast luminal cells and in orthotopic tumor xenografts in mice. IL-8 played also an important role in enhancing the proangiogenic effects of breast adipocytes. These results provide clear indication that IL-8 plays key roles in the activation of breast CAAs and acts as a major mediator for their paracrine protumorigenic effects. Thus, targeting CAAs by inhibiting the IL-8 pathway could have great therapeutic value.

Embelin inhibits abdominal aortic aneurysm through decreasing IL‑6‑induced STAT3 and NF‑κB inactivation

The aim of the present study was to investigate the effect of embelin on abdominal aortic aneurysm (AAA). AAA model mice were induced by chronic infusion of 1,000 ng/kg/min Angiotensin II. AAA model mice were treated with 25, 50 or 100 mg/kg embelin for 28 days. Embelin inhibited tumor necrosis factor‑α, interleukin (IL)‑1β, IL‑6, IL‑18 and malondialdehyde (MDA) level activities, increased superoxide dismutase, glutathione (GSH) and GSH peroxidase level activities and inhibited MDA level activities in AAA mice Embelin suppressed the secretion of matrix metalloproteinase‑9 protein expression, monocyte chemoattractant protein‑2 activity and epithelial neutrophil‑activating peptide expression levels in AAA mice. Embelin suppressed phosphorylated‑signal transducer and activator of transcription (STAT) 3, phosphorylated‑p38 mitogen‑activated protein kinase and nuclear factor (NF)‑κB protein expression in AAA mice. These findings indicate that embelin inhibits AAA through decreasing IL‑6‑induced STAT3, and NF‑κB inactivation.

Let-7b inhibits cancer-promoting effects of breast cancer-associated fibroblasts through IL-8 repression

Cancer-associated fibroblasts (CAFs) are major players in the development and spread of breast carcinomas through non-cell-autonomous signaling. These paracrine effects are under the control of several genes and microRNAs. We present here clear evidence that let-7b, a tumor suppressor microRNA, plays key roles in the persistent activation of breast stromal fibroblasts and their functional interplay with cancer cells. We have first shown that let-7b is down-regulated in CAFs as compared to their corresponding normal adjacent fibroblasts, and transient specific let-7b inhibition permanently activated breast fibroblasts through induction of the IL-6-related positive feedback loop. More importantly, let-7b-deficient cells promoted the epithelial-to-mesenchymal transition process in breast cancer cells in an IL-8-dependent manner, and also enhanced orthotopic tumor growth in vivo. On the other hand, overexpression of let-7b by mimic permanently suppressed breast myofibroblasts through blocking the positive feedback loop, which inhibited their paracrine pro-carcinogenic effects. Furthermore, we have shown that let-7b negatively controls IL-8, which showed higher expression in the majority of CAF cells as compared to their adjacent normal counterparts, indicating that IL-8 plays a major role in the carcinoma/stroma cross-talk. These findings support targeting active stromal fibroblasts through restoration of let-7b/IL-8 expression as a therapeutic option for breast carcinomas.

Inflammatory responses and inflammation-associated diseases in organs

Inflammation is a biological response of the immune system that can be triggered by a variety of factors, including pathogens, damaged cells and toxic compounds. These factors may induce acute and/or chronic inflammatory responses in the heart, pancreas, liver, kidney, lung, brain, intestinal tract and reproductive system, potentially leading to tissue damage or disease. Both infectious and non-infectious agents and cell damage activate inflammatory cells and trigger inflammatory signaling pathways, most commonly the NF-κB, MAPK, and JAK-STAT pathways. Here, we review inflammatory responses within organs, focusing on the etiology of inflammation, inflammatory response mechanisms, resolution of inflammation, and organ-specific inflammatory responses.

Inflammatory responses and inflammation-associated diseases in organs

Inflammation is a biological response of the immune system that can be triggered by a variety of factors, including pathogens, damaged cells and toxic compounds. These factors may induce acute and/or chronic inflammatory responses in the heart, pancreas, liver, kidney, lung, brain, intestinal tract and reproductive system, potentially leading to tissue damage or disease. Both infectious and non-infectious agents and cell damage activate inflammatory cells and trigger inflammatory signaling pathways, most commonly the NF-κB, MAPK, and JAK-STAT pathways. Here, we review inflammatory responses within organs, focusing on the etiology of inflammation, inflammatory response mechanisms, resolution of inflammation, and organ-specific inflammatory responses.

RNA-binding protein AUF1 suppresses miR-122 biogenesis by down-regulating Dicer1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the common cancers worldwide, especially in developing countries. Although the chronic infections of hepatitis B and C viruses have been established as the etiological factors of HCC, the mechanism for the tumorigenesis and development of HCC is still unclear. The liver-specific microRNA-122 (miR-122), an established tumor-suppressor miRNA, is often down-regulated in HCC, while the underlying mechanism is not well understood. Here we report that the AU-rich element-binding factor AUF1 suppresses the expression of Dicer1, the type III RNase that is required for microRNA maturation, leading to the inhibited biogenesis of miR-122. Overexpression of AUF1 led to the decreased expression of Dicer1 and miR-122, while the level of the miR-122 precursor (pre-miR-122) was increased. On the other hand, siRNA of AUF1 (siAUF1) increased the levels of Dicer1 mRNA and miR-122, but it reduced the abundance of pre-miR-122. Consistent with the reported data, this study demonstrated that AUF1 and Dicer1 showed opposite expression pattern in both human HCC tissues and cell lines. In addition, AUF1 inhibited the expression of Dicer1 by interacting with the 3′ untranslated region (3′UTR) and coding region of DICER1 mRNA. Moreover, the knockdown of AUF1 by siRNA altered the expression of other miRNAs and promoted HCC cell death. In conclusion, AUF1 down-regulates the expression miR-122 by interacting with the 3′UTR and coding region of DICER1 mRNA and suppressing Dicer1 expression. The AUF1/Dicer1/miR-122 pathway might play a critical role in the development of HCC.

The DNA methyl-transferase protein DNMT1 enhances tumor-promoting properties of breast stromal fibroblasts

The activation of breast stromal fibroblasts is a crucial step toward tumor growth and spread. Therefore, it is extremely important to understand the molecular basis of this activation and determine the molecules and the mechanisms responsible for its sustainability. In the present report we have shown that the DNA methyl-transferase protein DNMT1 is critical for the activation of breast stromal fibroblasts as well as the persistence of their active status. Indeed, we have first revealed DNMT1 up-regulation in most cancer-associated fibroblasts relative to their corresponding adjacent normal fibroblasts. This effect resulted from HuR-dependent stabilization of the DNMT1 mRNA. Furthermore, ectopic expression of DNMT1 activated primary normal breast fibroblasts and promoted their pro-carcinogenic effects, both in vitro and in orthotopic tumor xenografts. By contrast, specific DNMT1 knockdown normalized breast myofibroblasts and repressed their cancer-promoting properties. These effects were sustained through inhibition of the IL-6/STAT3/NF-κB epigenetic cancer/inflammation positive feedback loop. Furthermore, we have shown that DNMT1-related activation of breast fibroblasts is mediated through upregulation of the RNA binding protein AUF1, which is also part of the loop. The present data demonstrate the critical function of DNMT1 in breast cancer-related sustained activation of breast stromal fibroblasts.

Apigenin inhibits colonic inflammation and tumorigenesis by suppressing STAT3-NF-κB signaling

Apigenin is a naturally occurring compound with anti-inflammatory, antioxidant, and anticancer properties. Here, we investigated the effects of apigeninin inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). Apigenin effectively inhibited ulcerative colitis, a type of IBD, and CAC. Apigenin decreased myeloperoxidase (MPO), inflammatory cytokine and COX-2 levels, and it attenuated inflammatory cell infiltration in treated colon tissues as compared to untreated model colon tissues. Apigenin also reduced NF-κB and STAT3 activity in vitro and in vivo, thereby inhibiting inflammation and inflammation-induced carcinogenesis. Thus apigenin appears to inhibit inflammation and inflammation-induced carcinogenesisin IBD and CAC by suppressing STAT3-NF-κB signaling.

TXNDC5 synergizes with HSC70 to exacerbate the inflammatory phenotype of synovial fibroblasts in rheumatoid arthritis through NF-κB signaling

The upregulated expression of thioredoxin domain-containing protein 5 (TXNDC5) is associated with rheumatoid arthritis in patients and model mice. However, the underlying mechanism by which TXNDC5 influences the pathological activation of rheumatoid arthritis synovial fibroblasts (RASFs) remains unknown. In this study, we show that TXNDC5 expression in RASFs and their cytokine production are significantly upregulated in response to LPS, TNF-α and IL-6, but suppressed by transfection with TXNDC5-siRNA. TXNDC5 is further validated as the direct target of NF-κB signaling. Mechanistically, TXNDC5 directly interacts with heat shock cognate 70 protein (HSC70) to sequester it in the cytoplasm, and HSC70 silencing exerts the same effects as TXNDC5 on the biological activity of RASFs (for example, decreased cell viability, invasion and cytokine production). Furthermore, HSC70 activates NF-κB signaling by destabilizing IκBβ protein in the absence of LPS or facilitating its nuclear translocation in the presence of LPS. Importantly, TXNDC5 can also regulate the activity of NF-κB signaling in a HSC70-IκBβ-dependent manner. Taken together, by linking HSC70 and NF-κB signaling, TXNDC5 plays a pro-inflammatory role in RASFs, highlighting a potential approach to treat RA by blocking the TXNDC5/HSC70 interaction.

Phytomedicine-Modulating oxidative stress and the tumor microenvironment for cancer therapy

In spite of the current advances and achievements in systems biology and translational medicinal research, the current strategies for cancer therapy, such as radiotherapy, targeted therapy, immunotherapy and chemotherapy remain palliative or unsatisfactory due to tumor metastasis or recurrence after surgery/therapy, drug resistance, adverse side effects, and so on. Oxidative stress (OS) plays a critical role in chronic/acute inflammation, carcinogenesis, tumor progression, and tumor invasion/metastasis which is also attributed to the dynamic and complex properties and activities in the tumor microenvironment (TME). Re-educating or reprogramming tumor-associated stromal or immune cells in the TME provides an approach for restoring immune surveillance impaired by disease in cancer patients to increase overall survival and reduce drug resistance. Herbal medicines or plant-derived natural products have historically been a major source of anti-cancer drugs. Delving into the lore of herbal medicine may uncover new leads for anti-cancer drugs. Phytomedicines have been widely documented to directly or indirectly target multiple signaling pathways and networks in cancer cells. A combination of anti-cancer drugs and polypharmacological plant-derived extracts or compounds may offer a significant advantage in sensitizing the efficacy of monotherapy and overcoming drug-induced resistance in cancer patients. This review introduces several phytochemicals and phytoextracts derived from medicinal plants or dietary vegetables that have been studied for their efficacy in preclinical cancer models. We address the underlying modes of action of induction of OS and deregulation of TME-associated stromal cells, mediators and signaling pathways, and reference the related clinical investigations that look at the single or combination use of phytochemicals and phytoextracts to sensitize anti-cancer drug effects and/or overcome drug resistance.

AUF1 regulation of coding and noncoding RNA

AUF1 is a family of four RNA-binding proteins (RBPs) generated by alternative pre-messenger RNA (pre-mRNA) splicing, with canonical roles in controlling the stability and/or translation of mRNA targets based on recognition of AU-rich sequences within mRNA 3' untranslated regions. However, recent studies identifying AUF1 target sites across the transcriptome have revealed that these canonical functions are but a subset of its roles in posttranscriptional regulation of gene expression. In this review, we describe recent developments in our understanding of the RNA-binding properties of AUF1 together with their biochemical implications and roles in directing mRNA decay and translation. This is then followed by a survey of newly discovered activities for AUF1 proteins in control of miRNA synthesis and function, including miRNA assembly into microRNA (miRNA)-loaded RNA-induced silencing complexes (miRISCs), miRISC targeting to mRNA substrates, interplay with an expanding network of other cellular RBPs, and reciprocal regulatory relationships between miRNA and AUF1 synthesis. Finally, we discuss recently reported relationships between AUF1 and long noncoding RNAs and regulatory roles on viral RNA substrates. Cumulatively, these findings have significantly expanded our appreciation of the scope and diversity of AUF1 functions in the cell, and are prompting an exciting array of new questions moving forward. WIREs RNA 2017, 8:e1393. doi: 10.1002/wrna.1393 For further resources related to this article, please visit the WIREs website.