p16INK4Ainduces senescence and inhibits EMT through microRNA-141/microRNA-146b-5p-dependent repression of AUF1

miR-29b-3p Affects the Hypertrophy of Ligamentum Flavum in Lumbar Spinal Stenosis and its Mechanism

To explore the effect of miR-29b-3p on fibrosis and hypertrophy of ligamentum flavum (LF) in lumbar spinal stenosis (LSS) and its underlying mechanism. Patients with LSS and lumbar disc herniation (LDH) (control) undergoing posterior lumbar laminectomy were included in this study. Human LF samples were obtained for LF cell isolation, RNA, and protein extraction. Histomorphological analysis of LF was performed using hematoxylin-eosin (HE) staining. After isolation, culture, and transfection of primary LF cells, different transfection groups were constructed: NC-mimic, miR-29b-3p-mimic, NC-inhibitor, and miR-29b-3p-inhibitor. Quantitative real time polymerase chain reaction (qRT-PCR) was performed to detect the expression of miR-29b-3p in LF and LF cells. Western blot analysis detected the protein expressions of P16 and CyclinD1. ELISA detected the protein expressions of TGF-β1, Smad2, Smad3, TLR4, Type I collagen, and Type III collagen. Finally, LF cell viability was detected using the Cell Counting Kit-8 (CCK8) assay. The thickness of LF was significantly thicker in the LSS group compared to the LDH group (p < 0.05), accompanied by a higher calcification degree, more fibroblasts, and a larger area of collagen fiber proliferation. miR-29b-3p expression was significantly lower in LSS-derived LF tissues and cells than in LDH-derived tissues and cells (both p < 0.05). Compared to the NC-mimic group, the miR-29b-3p-mimic group exhibited significantly higher miR-29b-3p expression, decreased protein expressions of Type I collagen, Type III collagen, TGF-β1, Smad2, Smad3, TLR4, P16, and CyclinD1, and inhibited LF cell proliferation (all p < 0.05). As expected, the miR-29b-3p-inhibitor group displayed contrasting expression patterns (all p < 0.05). Compared to the phosphate buffer saline (PBS) group, the Trimethylamine-N-Oxide (TMAO) group showed significantly increased expressions of TGF-β1, Smad2, Smad3, TLR4, Type I collagen, Type III collagen, P16, and CyclinD1, as well as enhanced LF cell proliferation (all p < 0.05). However, there was no significant difference between the TMAO group and the Ang II group (all p > 0.05). Upregulation of miR-29b-3p expression may play a role in improving LF fibrosis and hypertrophy in LSS by inhibiting P16 expression and suppressing the activation of the TGF-β/Smad signaling pathway. This finding offers new insights into future gene modification therapy for this patient population.

Regulatory miRNAs in cancer cell recovery from therapy exposure and its implications as a novel therapeutic strategy for preventing disease recurrence

The desired outcome of cancer therapies is the eradication of disease. This can be achieved when therapy exposure leads to therapy-induced cancer cell death as the dominant outcome. Theoretically, a permanent therapy-induced growth arrest could also contribute to a complete response, which has the potential to lead to remission. However, preclinical models have shown that therapy-induced growth arrest is not always durable, as recovering cancer cell populations can contribute to the recurrence of cancer. Significant research efforts have been expended to develop strategies focusing on the prevention of recurrence. Recovery of cells from therapy exposure can occur as a result of several cell stress adaptations. These include cytoprotective autophagy, cellular quiescence, a reversable form of senescence, and the suppression of apoptosis and necroptosis. It is well documented that microRNAs regulate the response of cancer cells to anti-cancer therapies, making targeting microRNAs therapeutically a viable strategy to sensitization and the prevention of recovery. We propose that the use of microRNA-targeting therapies in prolonged sequence, that is, a significant period after initial therapy exposure, could reduce toxicity from the standard combination strategy, and could exploit new epigenetic states essential for cancer cells to recover from therapy exposure. In a step toward supporting this strategy, we survey the available scientific literature to identify microRNAs which could be targeted in sequence to eliminate residual cancer cell populations that were arrested as a result of therapy exposure. It is our hope that by successfully identifying microRNAs which could be targeted in sequence we can prevent disease recurrence.

RNA binding proteins in senescence: A potential common linker for age-related diseases?

Aging represents the major risk factor for the onset and/or progression of various disorders including neurodegenerative diseases, metabolic disorders, and bone-related defects. As the average age of the population is predicted to exponentially increase in the coming years, understanding the molecular mechanisms underlying the development of aging-related diseases and the discovery of new therapeutic approaches remain pivotal. Well-reported hallmarks of aging are cellular senescence, genome instability, autophagy impairment, mitochondria dysfunction, dysbiosis, telomere attrition, metabolic dysregulation, epigenetic alterations, low-grade chronic inflammation, stem cell exhaustion, altered cell-to-cell communication and impaired proteostasis. With few exceptions, however, many of the molecular players implicated within these processes as well as their role in disease development remain largely unknown. RNA binding proteins (RBPs) are known to regulate gene expression by dictating at post-transcriptional level the fate of nascent transcripts. Their activity ranges from directing primary mRNA maturation and trafficking to modulation of transcript stability and/or translation. Accumulating evidence has shown that RBPs are emerging as key regulators of aging and aging-related diseases, with the potential to become new diagnostic and therapeutic tools to prevent or delay aging processes. In this review, we summarize the role of RBPs in promoting cellular senescence and we highlight their dysregulation in the pathogenesis and progression of the main aging-related diseases, with the aim of encouraging further investigations that will help to better disclose this novel and captivating molecular scenario.

Exploring the Potential Role of Circulating microRNAs as Biomarkers for Predicting Clinical Response to Neoadjuvant Therapy in Breast Cancer

Breast cancer (BC) is a leading cause of cancer-related deaths among women worldwide. Neoadjuvant therapy (NAT) is increasingly being used to reduce tumor burden prior to surgical resection. However, current techniques for assessing tumor response have significant limitations. Additionally, drug resistance is commonly observed, raising a need to identify biomarkers that can predict treatment sensitivity and survival outcomes. Circulating microRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and have been shown to play a significant role in cancer progression as tumor inducers or suppressors. The expression of circulating miRNAs has been found to be significantly altered in breast cancer patients. Moreover, recent studies have suggested that circulating miRNAs can serve as non-invasive biomarkers for predicting response to NAT. Therefore, this review provides a brief overview of recent studies that have demonstrated the potential of circulating miRNAs as biomarkers for predicting the clinical response to NAT in BC patients. The findings of this review will strengthen future research on developing miRNA-based biomarkers and their translation into medical practice, which could significantly improve the clinical management of BC patients undergoing NAT.

The function and regulatory mechanism of RNA-binding proteins in breast cancer and their future clinical treatment prospects

Breast cancer is the most common female malignancy, but the mechanisms regulating gene expression leading to its development are complex. In recent years, as epigenetic research has intensified, RNA-binding proteins (RBPs) have been identified as a class of posttranscriptional regulators that can participate in regulating gene expression through the regulation of RNA stabilization and degradation, intracellular localization, alternative splicing and alternative polyadenylation, and translational control. RBPs play an important role in the development of normal mammary glands and breast cancer. Functional inactivation or abnormal expression of RBPs may be closely associated with breast cancer development. In this review, we focus on the function and regulatory mechanisms of RBPs in breast cancer, as well as the advantages and challenges of RBPs as potential diagnostic and therapeutic targets in breast cancer, and discuss the potential of RBPs in clinical treatment.

Emerging Role of Non-Coding RNAs in Senescence

Senescence is defined as a gradual weakening of functional features of a living organism. Cellular senescence is a process that is principally aimed to remove undesirable cells by prompting tissue remodeling. This process is also regarded as a defense mechanism induced by cellular damage. In the course of oncogenesis, senescence can limit tumor progression. However, senescence participates in the pathoetiology of several disorders such as fibrotic disorders, vascular disorders, diabetes, renal disorders and sarcopenia. Recent studies have revealed contribution of different classes of non-coding RNAs in the cellular senescence. Long non-coding RNAs, microRNAs and circular RNAs are three classes of these transcripts whose contributions in this process have been more investigated. In the current review, we summarize the available literature on the impact of these transcripts in the cellular senescence.

Epithelial-mesenchymal transition: Insights into nickel-induced lung diseases

Nickel compounds are environmental toxicants, prevalent in the atmosphere due to their widespread use in several industrial processes, extensive consumption of nickel containing products, as well as burning of fossil fuels. Exposure to nickel is associated with a multitude of chronic inflammatory lung diseases including asthma, chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis. In addition, nickel exposure is implicated in the development of nasal and lung cancers. Interestingly, a common pathogenic mechanism underlying the development of diseases associated with nickel exposure is epithelial-mesenchymal transition (EMT). EMT is a process by which the epithelial cells lose their junctions and polarity and acquire mesenchymal traits, including increased ability to migrate and invade. EMT is a normal and essential physiological process involved in differentiation, development and wound healing. However, EMT also contributes to a number of pathological conditions, including fibrosis, cancer and metastasis. Growing evidence suggest that EMT induction could be an important outcome of nickel exposure. In this review, we discuss the role of EMT in nickel-induced lung diseases and the mechanisms associated with EMT induction by nickel exposure.

Response Assessment With Molecular Characterization of Circulating Tumor Cells and Plasma MicroRNA Profiling in Patients With Locally Advanced Breast Cancer During Neoadjuvant Chemotherapy

BACKGROUND

Cells detaching from the primary tumor site are metastasis initiator cells, and the detection of CTC, known as liquid biopsy, is an important test of biomarkers of cancer progression. We investigated the molecular characterization of circulating tumor cells (CTCs), profiled the plasma microRNA (miR) content, and analyzed the relationship with the clinical outcomes by sampling the peripheral blood from patients with locally advanced breast cancer before and after neoadjuvant chemotherapy.

PATIENTS AND METHODS

Markers of breast cancer, epithelial-mesenchymal transition (EMT), drug resistance, and stem cells were used for CTC isolation and characterization. Plasma miR profiles were obtained from selected patients with CTC positivity determined using next-generation sequencing.

RESULTS

The proportion of CTC, EMT, and stem cell marker positivity was 16.7%, 8.3%, and 25% before and 18.2%, 15.2%, and 9.1% after treatment, respectively. A significant correlation was found between the pretreatment CTCs and ALDH1 positivity (P = .0245). These CTCs with stemness properties were observed in most hormone receptor-positive, human epidermal growth factor receptor 2-negative cases and were also present with a high incidence in cases of early metastasis. miR-146b-5p and miR-199a-5p, which are involved in metastasis, invasion, and EMT, were accompanied by CTC positivity, and miR-4646-3p was associated with the development of early metastasis.

CONCLUSIONS

Molecular characterization of CTCs and miR profiling of serial samples from patients with locally advanced breast cancer during neoadjuvant chemotherapy appears to be a very useful in predicting cure and clinical course and might be a key to developing new targeted therapies.

Lcn2-derived Circular RNA (hsa_circ_0088732) Inhibits Cell Apoptosis and Promotes EMT in Glioma via the miR-661/RAB3D Axis

Background: Glioma is the most common malignant tumor of the central nervous system, and often displays invasive growth. Recently, circular RNA (circRNA), which is a novel non-coding type of RNA, has been shown to play a vital role in glioma tumorigenesis. However, the functions and mechanism of lipocalin-2 (Lcn2)-derived circular RNA (hsa_circ_0088732) in glioma progression remain unclear.

Methods: We evaluated hsa_circ_0088732 expression by fluorescence in situ hybridization (FISH), Sanger sequencing, and PCR assays. Cell apoptosis was evaluated by flow cytometry and Hoechst 33258 staining. Transwell migration and invasion assays were performed to measure cell metastasis and viability. In addition, the target miRNA of hsa_circ_0088732 and the target gene of miR-661 were predicted by a bioinformatics analysis, and the interactions were verified by dual-luciferase reporter assays. RAB3D expression was analyzed by an immunochemistry assay, and E-cadherin, N-cadherin, and vimentin protein expression were examined by western blot assays. A mouse xenograft model was developed and used to analyze the effects of hsa_circ_0088732 on glioma growth in vivo.

Results: We verified that hsa_circ_0088732 is circular and highly expressed in glioma tissues. Knockdown of hsa_circ_0088732 induced glioma cell apoptosis and inhibited glioma cell migration, invasion, and epithelial-mesenchymal transition (EMT). We found that hsa_circ_0088732 negatively regulated miR-661 by targeting miR-661, and RAB3D was a target gene of miR-661. In addition, inhibition of miR-661 promoted glioma cell metastasis and suppressed cell apoptosis. Knockdown of RAB3D induced cell apoptosis and suppressed cell metastasis. Moreover, hsa_circ_0088732 accelerated glioma progression through its effects on the miR-661/RAB3D axis. Finally, results from a mouse xenograft model confirmed that knockdown of hsa_circ_0088732 induced miR-661 expression, resulting in suppression of RAB3D expression and inhibition of tumor growth in vivo.

Conclusion: We demonstrated that hsa_circ_0088732 facilitated glioma progression by sponging miR-661 to increase RAB3D expression. This study provides a theoretical basis for understanding the development and occurrence of glioma, as well as for the development of targeted drugs.

The Oncogene PIM1 Contributes to Cellular Senescence by Phosphorylating Staphylococcal Nuclease Domain-Containing Protein 1 (SND1)

Background

The oncogene PIM1, encoding a constitutively active serine/threonine protein kinase, is involved in the regulation of cell proliferation, survival, differentiation, and apoptosis. There is a growing body of literature on the role of PIM1-mediated cellular senescence, but the precise mechanism remains unclear.

Material/Methods

Silver staining and LC–MS/MS analysis were performed to investigate the protein interacting with PIM1. Immunofluorescence, Co-IP, and Western blot assay were used to assess the interaction of PIM1 and SND1. EdU incorporation and CCK8 assay were used to detect cell proliferation and immunohistochemistry was used to detect the level of the indicated protein.

Results

We found that PIM1 can bind directly and phosphorylate SND1. In addition, decreased expression of SND1 leads to the upregulation of SASP. SND1 is involved in cellular senescence induced by PIM1.

Conclusions

We investigated the role of PIM1 in oncogene-induced normal cellular senescence. Our results promote further understanding of the mechanisms underlying OIS and suggest potential applications for preventing tumorigenesis.

Interactive functions of microRNAs in the miR-23a-27a-24-2 cluster and the potential for targeted therapy in cancer

MicroRNAs (miRNAs) are small noncoding RNAs about 19-22 nucleotides in length. Growing evidence has reported the significant role of miRNAs in various cancer-associated biological processes, such as proliferation, differentiation, apoptosis, metabolism, invasion, metastasis, and drug resistance. However, most studies focus on the targets of some individual miRNAs; the interactive and global functions of diverse miRNAs are still unclear and the phenomenon of the gathering of miRNAs in clusters has always been ignored. On the other hand, the fact that a single miRNA may regulate many genes and that numerous mRNAs are regulated by the same miRNA also makes it imperative to further study the cooperating characteristics of miRNAs in cancer. MiR-23a-27a-24-2 is located in the human chromosome 9q22, forming three mature miRNAs: miR-23a, miR27a, and miR-24, which are expressed abnormally in many malignant tumors. This review aims to summarize the interactive functions of miRNAs in miR-23a-27a-24-2 clusters in cancer from the perspectives of the regulation network, tumor microenvironment, and targeted therapy.

Doxorubicin-Induced Cancer Cell Senescence Shows a Time Delay Effect and Is Inhibited by Epithelial-Mesenchymal Transition (EMT)

Background

Senescence is a natural barrier for the body to resist the malignant transformation of its own cells. This work investigated the senescence characteristics of cancer cells in vitro.

Material/Methods

Human cervical cancer HeLa cells were treated with different concentrations of doxorubicin for 3 days, with or without subsequent extended culture in drug-free medium for 6 days. Senescent cell ratios between these 2 culture schemes were calculated. Expression of 2 senescence-associated secretory factors, IL-6 and IL-8, were detected by RT-PCR and ELISA. Doxorubicin treatment induced epithelial-mesenchymal transition in cancer cells. The proportions of senescent cells in epithelial-like and mesenchymal-like sub-groups were calculated. Doxorubicin-treated HeLa cells were stained with Vimentin antibody and sorted by flow cytometry. Senescent cell marker p16^INK4a and IL-8 expression in Vimentin-high and Vimentin-low cells were detected by Western blot.

Results

We found that less than 1% of HeLa cells showed senescence phenotype after treatment with doxorubicin for 3 days. However, the proportion of senescent cells was significantly increased when the doxorubicin-treated cells were subsequently cultured in drug-free medium for another 6d. RT-PCR and ELISA results showed that this prolonged culture method could further improve the expression of IL-6 and IL-8. We also found that the senescent cells were mainly epithelial-like type and few presented mesenchymal-like shape. p16^INK4a and IL-8 expression were decreased in cell fraction with higher Vimentin expression.

Conclusions

Our results suggested the existence of time delay effect in doxorubicin-induced senescence of HeLa cells, and epithelial-mesenchymal transition may resist doxorubicin-induced cell senescence.

Anti-tumor effect of CDK inhibitors on CDKN2A-defective squamous cell lung cancer cells

BACKGROUND

Squamous cell lung cancer (SqCLC) is a distinct histologic subtype of non-small cell lung cancer (NSCLC). Although the discovery of driver mutations and their targeted drugs has remarkably improved the treatment outcomes for lung adenocarcinoma, currently no such molecular target is clinically available for SqCLC. The CDKN2A locus at 9p21 encodes two alternatively spliced proteins, p16^INK4a (p16) and p14^ARF (p14), which function as cell cycle inhibitors. The Cancer Genome Atlas (TCGA) project revealed that CDKN2A is inactivated in 72% of SqCLC cases. In addition, it was found that CDKN2A mutations are significantly more common in SqCLC than in adenocarcinoma. Down-regulation of p16 and p14 by CDKN2A gene inactivation leads to activation of cyclin-dependent kinases (CDKs), thereby permitting constitutive phosphorylation of Rb and subsequent cell cycle progression. Here, we hypothesized that CDK inhibition may serve as an attractive strategy for the treatment of CDKN2A-defective SqCLC.

METHODS

We investigated whether the CDK inhibitors flavopiridol and dinaciclib may exhibit antitumor activity in CDKN2A-defective SqCLC cells compared to control cells. The cytotoxic effect of the CDK inhibitors was evaluated using cell viability assays, and the induction of apoptosis was assessed using TUNEL assays and Western blot analyses. Finally, anti-tumor effects of the CDK inhibitors on xenografted cells were investigated in vivo.

RESULTS

We found that flavopiridol and dinaciclib induced cytotoxicity by enhancing apoptosis in CDKN2A-defective SqCLC cells, and that epithelial to mesenchymal transition (EMT) decreased and autophagy increased during this process. In addition, we found that autophagy had a cytoprotective role.

CONCLUSION

Our data suggest a potential role of CDK inhibitors in managing CDKN2A-defective SqCLC.

The Function of Ophiocordyceps sinensis in Airway Epithelial Cell Senescence in a Rat COPD Model

Ophiocordyceps sinensis (O. sinensis) seems to be able to alleviate airway epithelial cell senescence in chronic obstructive pulmonary disease (COPD). The objective of the study is to evaluate the effect of O. sinensis on airway epithelial senescence in the COPD model both in vitro and in vivo. We observed the expression of P16 and P21 in the airway epithelia of 30 patients with COPD. The optimal concentration of O. sinensis and exposure time of the cigarette smoke extract (CSE) were determined in vitro, and senescence-associated β-galactosidase (SA-β-gal) and 5-bromodeoxyuridine (BrdU) were used to evaluate the senescence and proliferation of human bronchial epithelial (16HBE) cells pretreated with O. sinensis by staining kits. COPD model rats were treated with O. sinensis at various concentrations to determine the changes in P16 and P21 expression in airway epithelial tissues. It was found that the expression levels of P16 and P21 were higher in the airway epithelia of COPD patients than those in the control group based on immunohistochemical staining, real-time quantitative PCR, and western blotting. The CSE could induce 16HBE cell senescence, and O. sinensis could alleviate CSE-induced senescence and promote the proliferation of 16HBE cells. The expression levels of P16 and P21 were also higher in the airway epithelia of COPD model rats; however, the levels of P16 and P21 in the groups treated with all concentrations of O. sinensis were obviously lower than those in the COPD model group based on real-time quantitative PCR and western blotting. In conclusion, the CSE can induce airway epithelium senescence, and O. sinensis can inhibit CSE-induced cellular senescence, both in vitro and in vivo.

Role of microRNAs in senescence and its contribution to peripheral neuropathy in the arsenic exposed population of West Bengal, India

Arsenic induced senescence (AIS) has been identified in the population of West Bengal, India very recently. Also there is a high incidence of arsenic induced peripheral neuropathy (PN) throughout India. However, the epigenetic regulation of AIS and its contribution in arsenic induced PN remains unexplored. We recruited seventy two arsenic exposed and forty unexposed individuals from West Bengal to evaluate the role of senescence associated miRNAs (SA-miRs) in AIS and their involvement if any, in PN. The downstream molecules of the miRNA associated with the disease outcome, was also checked by immuoblotting. In vitro studies were conducted with HEK 293 cells and sodium arsenite exposure. Our results show that all the SA-miRs were upregulated in comparison to unexposed controls. miR-29a was the most significantly altered, highest expression being in the arsenic exposed group with PN, suggesting its association with the occurrence of PN. We looked for the expression of peripheral myelin protein 22 (PMP22), a specific target of miR-29a associated with myelination and found that both in vitro and in vivo results showed over-expression of the protein. Since this was quite contrary to miRNA regulation, we checked for intermediate players β-catenin and GSK-3β upon arsenic exposure which affects PMP22 expression. We found that β-catenin was upregulated in vitro and was also highest in the arsenic exposed group with PN while GSK-3β followed the reverse pattern. Our findings suggest that arsenic exposure alters the expression of SA-miRs and the mir-29a/beta catenin/PMP22 axis might be responsible for arsenic induced PN.

The p16/miR-217/EGR1 pathway modulates age-related tenogenic differentiation in tendon stem/progenitor cells

Previous studies have shown that the differentiation potential declines with the age of progenitor cells and is linked to altered levels of senescence markers. The purpose of this study was to test whether senescence marker p16 affects age-related tenogenic differentiation in tendon stem/progenitor cells (TSPCs). Young and aged TSPCs were isolated from young/healthy and aged/degenerated human Achilles tendons, respectively. Cellular aging and capacity for tenogenic differentiation were examined. The results showed that the tenogenic differentiation capacity of TSPCs significantly decreases with advancing age. TSPCs from elderly donors showed upregulation of senescence-associated β-galactosidase and p16 and concurrently a decrease in Type I collagen concentration and in the expressions of tendon-related markers: Scx, Tnmd, Bgn, Dcn, Col1, and Col3. Overexpression of p16 significantly inhibited tenogenic differentiation of young TSPCs. Analysis of the mechanism revealed that this effect is mediated by microRNA-217 and its target EGR1. These results indicated that p16 inhibits tenogenic differentiation of TSPCs via microRNA signaling pathways, which may serve as a potential target for the prevention or treatment in the future.

Cell-to-cell communication: microRNAs as hormones

Mammalian cells can release different types of extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies. Accumulating evidence suggests that EVs play a role in cell-to-cell communication within the tumor microenvironment. EVs' components, such as proteins, noncoding RNAs [microRNAs (miRNAs), and long noncoding RNAs (lncRNAs)], messenger RNAs (mRNAs), DNA, and lipids, can mediate paracrine signaling in the tumor microenvironment. Recently, miRNAs encapsulated in secreted EVs have been identified in the extracellular space. Mature miRNAs that participate in intercellular communication are released from most cells, often within EVs, and disseminate through the extracellular fluid to reach remote target cells, including tumor cells, whose phenotypes they can influence by regulating mRNA and protein expression either as tumor suppressors or as oncogenes, depending on their targets. In this review, we discuss the roles of miRNAs in intercellular communication, the biological function of extracellular miRNAs, and their potential applications for diagnosis and therapeutics. We will give examples of miRNAs that behave as hormones.

AUF1 modulates TGF-β signal in renal tubular epithelial cells via post-transcriptional regulation of Nedd4L expression

Posttranscriptional regulation process plays important roles in renal disease pathogenesis. AU-rich element RNA-binding protein (AUF1) interacts with and destabilizes mRNAs containing AU-rich elements (AREs) in their 3'UTR. The current study demonstrated that AUF1 was increased in unilateral ureteral obstruction (UUO) animal models. While proliferation and migration of HK2 cells was unaltered by AUF1 downregulation under normal condition, proliferative inhibition and migratory promotion mediated by TGF-β was significantly compromised. Mechanically, AUF1 downregulation decreased phosphorylated Smad2/3 via increasing their E3 ligase Nedd4L at the posttranscriptional level. In addition, the current study identified Nedd4L as a previously unreported target of AUF1. AUF1 regulates Nedd4L expression at the posttranscriptional level by interaction with AREs in the 3'UTR of the Nedd4L mRNA. Collectively, the current study indicates that AUF1 might be a potential player in renal tubulointerstitial fibrosis through modulation of TGF-β signal transduction via posttranscriptional regulation of Nedd4L.

BMI-1 is a potential therapeutic target in diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG) is a poor-prognosis pediatric brain tumor. No effective curative therapy is currently available and no therapeutic advances have been made in several decades. BMI-1 is a member of the multimeric protein complex Polycomb repressor complex 1. It is highly expressed in a number of diseases and malignancies and has been implicated in self-renewal of normal and cancer cells, and in DNA damage signaling. The role of BMI-1 in DIPG is largely unknown. Here, we show that BMI-1 is highly expressed in tumor tissue samples of DIPG patients and in patient-derived cancer stem-like cells. BMI-1 downregulation leads to the inhibition of DIPG patient-derived neurosphere cell proliferation, cell cycle signaling, self-renewal, telomerase expression and activity, and suppresses DIPG cell migration. Moreover, targeted inhibition of BMI-1 sensitizes DIPG cells to radiomimetic drug-induced DNA damage. Together, our data validate BMI-1 as a potential therapeutic target to treat children with DIPG.