DDX17 (P72), a Sox2 binding partner, promotes stem-like features conferred by Sox2 in a small cell population in estrogen receptor-positive breast cancer

Transcriptional co-activators: emerging roles in signaling pathways and potential therapeutic targets for diseases

Specific cell states in metazoans are established by the symphony of gene expression programs that necessitate intricate synergic interactions between transcription factors and the co-activators. Deregulation of these regulatory molecules is associated with cell state transitions, which in turn is accountable for diverse maladies, including developmental disorders, metabolic disorders, and most significantly, cancer. A decade back most transcription factors, the key enablers of disease development, were historically viewed as 'undruggable'; however, in the intervening years, a wealth of literature validated that they can be targeted indirectly through transcriptional co-activators, their confederates in various physiological and molecular processes. These co-activators, along with transcription factors, have the ability to initiate and modulate transcription of diverse genes necessary for normal physiological functions, whereby, deregulation of such interactions may foster tissue-specific disease phenotype. Hence, it is essential to analyze how these co-activators modulate specific multilateral processes in coordination with other factors. The proposed review attempts to elaborate an in-depth account of the transcription co-activators, their involvement in transcription regulation, and context-specific contributions to pathophysiological conditions. This review also addresses an issue that has not been dealt with in a comprehensive manner and hopes to direct attention towards future research that will encompass patient-friendly therapeutic strategies, where drugs targeting co-activators will have enhanced benefits and reduced side effects. Additional insights into currently available therapeutic interventions and the associated constraints will eventually reveal multitudes of advanced therapeutic targets aiming for disease amelioration and good patient prognosis.

DDX17 induces epithelial-mesenchymal transition and metastasis through the miR-149-3p/CYBRD1 pathway in colorectal cancer

DEAD box helicase 17 (DDX17) has been reported to be involved in the initiation and development of several cancers. However, the functional role and mechanisms of DDX17 in colorectal cancer (CRC) malignant progression and metastasis remain unclear. Here, we reported that DDX17 expression was increased in CRC tissues compared with noncancerous mucosa tissues and further upregulated in CRC liver metastasis compared with patient-paired primary tumors. High levels of DDX17 were significantly correlated with aggressive phenotypes and worse clinical outcomes in CRC patients. Ectopic expression of DDX17 promoted cell migration and invasion in vitro and in vivo, while the opposite results were obtained in DDX17-deficient CRC cells. We identified miR-149-3p as a potential downstream miRNA of DDX17 through RNA sequencing analysis, and miR-149-3p displayed a suppressive effect on the metastatic potential of CRC cells. We demonstrated that CYBRD1 (a ferric reductase that contributes to dietary iron absorption) was a direct target of miR-149-3p and that miR-149-3p was required for DDX17-mediated regulation of CYBRD1 expression. Moreover, DDX17 contributed to the metastasis and epithelial to mesenchymal transition (EMT) of CRC cells via downregulation of miR-149-3p, which resulted in increased CYBRD1 expression. In conclusion, our findings not only highlight the significance of DDX17 in the aggressive development and prognosis of CRC patients, but also reveal a novel mechanism underlying DDX17-mediated CRC cell metastasis and EMT progression through manipulation of the miR-149-3p/CYBRD1 pathway.

DDX17 promotes the growth and metastasis of lung adenocarcinoma

DEAD box RNA helicase 17 (DDX17) has been shown to be an RNA binding protein involved in RNA metabolism and associated with cancer progression. However, the biological role of DDX17 in the pathogenesis of lung adenocarcinoma (LUAD) has not been well characterized. Here, we demonstrated that DDX17 promoted the proliferation, migration and invasion of H1299 and A549 lung adenocarcinoma cells. Analyses of public datasets showed that DDX17 is upregulated in LUAD specimens. Our tumor xenograft models confirmed the in vivo promoting role of DDX17 in the growth and metastasis of LUAD. Mechanistic analyses further revealed that DDX17 protein interacts with the mRNA of MYL9 and MAGEA6 and upregulates their levels. MYL9 could mediate the function of DDX17 to regulate the actin cytoskeleton rearrangement and cell adhesion, particularly by modulating the stress fiber and focal adhesion formation, whereas DDX17 might inhibit the autophagy process through MAGEA6/AMPKα1 axis in LUAD cells. Collectively, our study revealed the oncogenic role and pathways of DDX17 in LUAD.

DDX5 and DDX17—multifaceted proteins in the regulation of tumorigenesis and tumor progression

DEAD-box (DDX)5 and DDX17, which belong to the DEAD-box RNA helicase family, are nuclear and cytoplasmic shuttle proteins. These proteins are expressed in most tissues and cells and participate in the regulation of normal physiological functions; their abnormal expression is closely related to tumorigenesis and tumor progression. DDX5/DDX17 participate in almost all processes of RNA metabolism, such as the alternative splicing of mRNA, biogenesis of microRNAs (miRNAs) and ribosomes, degradation of mRNA, interaction with long noncoding RNAs (lncRNAs) and coregulation of transcriptional activity. Moreover, different posttranslational modifications, such as phosphorylation, acetylation, ubiquitination, and sumoylation, endow DDX5/DDX17 with different functions in tumorigenesis and tumor progression. Indeed, DDX5 and DDX17 also interact with multiple key tumor-promoting molecules and participate in tumorigenesis and tumor progression signaling pathways. When DDX5/DDX17 expression or their posttranslational modification is dysregulated, the normal cellular signaling network collapses, leading to many pathological states, including tumorigenesis and tumor development. This review mainly discusses the molecular structure features and biological functions of DDX5/DDX17 and their effects on tumorigenesis and tumor progression, as well as their potential clinical application for tumor treatment.

Development and validation of novel prognostic models based on RNA-binding proteins in breast cancer

Objectives

We aimed to construct novel prognostic models based on RNA-binding proteins (RBPs) in breast cancer (BRCA) and explore their roles in this disease and their effects on tumor-infiltrating immune cells (TIICs).

Methods

Datasets were downloaded from the Gene Expression Omnibus (GEO) database. Functions and prognostic values of RBPs were systematically investigated using a series of bioinformatics analysis methods. TIICs were assessed using CIBERSORT.

Results

Overall, 138 differentially expressed RBPs were identified, of which 86 were upregulated and 52 were downregulated. Of these, 13 RBPs were identified as prognosis-related and adopted to construct an overall survival (OS) model, while 12 RBPs were used for the relapse-free survival (RFS) model. High-risk patients had poorer OS and RFS rates than low-risk patients. The results indicate that the OS and RFS models are good prognostic models with reliable predictive abilities. In addition, the proportions of CD8, CD4 naïve, and CD4 memory resting T cells, as well as resting dendritic cells, were significantly different between the low-risk and high-risk groups in the OS model.

Conclusions

OS and RFS signatures can be used as reliable BRCA prognostic biomarkers. This work will help understand the prognostic roles and functions of RBPs in BRCA.

The RNA helicases DDX5 and DDX17 facilitate neural differentiation of human pluripotent stem cells NTERA2

AIMS

Understanding human neurogenesis is critical toward regenerative medicine for neurodegeneration. However, little is known how neural differentiation is regulated by DEAD box-containing RNA helicases, which comprise a diverse class of RNA remodeling enzymes.

MATERIALS AND METHODS

ChIP-seq was utilized to identify binding sites of DDX5 and DDX17 in both human pluripotent stem cell (hPSC) line NTERA2 and their retinoic acid-induced neural derivatives. RNA-seq was used to elucidate genes differentially expressed upon depletion of DDX5 and DDX17. Neurosphere assay, flow cytometry, and immunofluorescence staining were performed to test the effect of depletion of the two RNA helicases in neural differentiation.

KEY FINDINGS

We show here that expression of DDX5 and DDX17 is abundant throughout neural differentiation of NTERA2, and is mostly localized within the nucleus. The two RNA helicases occupy chromatin genome-wide at regions associated with neurogenesis-related genes in both hPSCs and their neural derivatives. Further, both DDX5 and DDX17 are mutually required for controlling transcriptional expression of these genes, but are not important for maintenance of stem cell state of hPSCs. In contrast, they facilitate early neural differentiation of hPSCs, generation of neurospheres from the stem cells, and transcriptional expression of key neurogenic transcription factors such as SOX1 and PAX6 during neural differentiation. Importantly, DDX5 and DDX17 are critical for differentiation of hPSCs toward NESTIN- and TUBB3-positive cells, which represent neural progenitors and mature neurons, respectively.

SIGNIFICANCE

Collectively, our findings suggest the role of DDX5 and DDX17 in transcriptional regulation of genes involved in neurogenesis, and hence in neural differentiation of hPSCs.

DEAD-box helicase 27 enhances stem cell-like properties with poor prognosis in breast cancer

Background

Although the rapid development of diagnosis and treatment has improved prognosis in early breast cancer, challenges from different therapeutic response remain due to breast cancer heterogeneity. DEAD-box helicase 27 (DDX27) had been proved to influence ribosome biogenesis and identified as a promoter in gastric and colorectal cancer associated with stem cell-like properties, while the impact of DDX27 on breast cancer prognosis and biological functions is unclear. We aimed to explore the influence of DDX27 on stem cell-like properties and prognosis in breast cancer.

Methods

The expression of DDX27 was evaluated in 24 pairs of fresh breast cancer and normal tissue by western blot. We conducted Immunohistochemical (IHC) staining in paraffin sections of 165 breast cancer patients to analyze the expression of DDX27 and its correlation to stemness biomarker. The Cancer Genome Atlas-Breast Cancer (TCGA-BRCA) database and the Clinical Proteomic Tumor Analysis Consortium (CPTAC) database were used to analyze the expression of DDX27 in breast cancer. Kaplan–Meier survival analysis were used to investigate the implication of DDX27 on breast cancer prognosis. Western blot, CCK-8 assay, Transwell assay and wound-healing assay were carried out to clarify the regulation of DDX27 on stem cell-like properties in breast cancer cells. Gene Set Enrichment Analysis (GSEA) was performed to analyze the potential molecular mechanisms of DDX27 in breast cancer.

Results

DDX27 was significantly high expressed in breast cancer compared with normal tissue. High expression of DDX27 was related to larger tumor size (p = 0.0005), positive lymph nodes (p = 0.0008), higher histological grade (p = 0.0040), higher ki-67 (p = 0.0063) and later TNM stage (p < 0.0001). Patients with high DDX27 expression turned out a worse prognosis on overall survival (OS, p = 0.0087) and disease-free survival (DFS, p = 0.0235). Overexpression of DDX27 could enhance the expression of biomarkers related to stemness and promote stem cell-like activities such as proliferation and migration in breast cancer cells.

Conclusion

DDX27 can enhance stem cell-like properties and cause poor prognosis in breast cancer, also may be expected to become a potential biomarker for breast cancer therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03011-0.

AXL Overexpression in Tumor-Derived Endothelial Cells Promotes Vessel Metastasis in Patients With Hepatocellular Carcinoma

Portal vein tumor thrombus (PVTT) is one of the most serious forms of hepatocellular carcinoma (HCC) vessel metastasis and has a poor survival rate. However, the molecular mechanism of PVTT has not yet been elucidated. In this study, the molecular mechanism of AXL expressed in tumor-derived endothelial cells (TECs) in vessel metastasis was investigated. High AXL expression was observed in TECs, but not in the tumor cells of HCC patients with PVTT and this was associated with poor overall survival (OS) and disease-free survival (DFS). AXL overexpression was positively associated with CD 31 expression both in vitro and in vivo. AXL promoted the cell proliferation, tube formation, and migration of both TECs and normal endothelial cells (NECs). High expression of AXL in TECs promoted the cell migration, but not the proliferation of HCC cells. Further studies demonstrated that AXL promoted cell migration and tube formation through activation of the PI3K/AKT/SOX2/DKK-1 axis. AXL overexpression in HUVECs promoted tumor growth and liver or vessel metastasis of HCC in xenograft nude mice, which could be counteracted by treatment with R428, an AXL inhibitor. R428 reduced tumor growth and CD 31 expression in HCC in PDX xenograft nude mice. Therefore, AXL over-expression in TECs promotes vessel metastasis of HCC, which indicates that AXL in TECs could be a potential therapeutic target in HCC patients with PVTT.

Identification of gene signatures and potential therapeutic targets for acquired chemotherapy resistance in gastric cancer patients

BACKGROUND

Gastric cancer (GC) is the most common type of gastrointestinal cancer, and has been studied extensively. However, resistance to chemotherapeutic agents has become a major problem, leading to treatment failure. This study aimed to investigate the molecular mechanisms mediating acquired resistance to cisplatin and fluorouracil (CF) combination-based chemotherapy in GC patients.

METHODS

The microarray datasets (GSE14209, GSE30070) were downloaded from the Gene Expression Omnibus (GEO) database to identify differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) using the limma package in R/Bioconductor. Possible targets of the DEMs were predicted using miRWalk, and the putative miRNA-mRNA regulatory network was constructed using Cytoscape software. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) analyses were then conducted and visualized using the Search Tool for Retrieval of Interacting Genes (STRING) and Cytoscape. The prognostic value of hub genes was revealed by Kaplan-Meier Plotter. The causal relationships and interactions between proteins were displayed using DisNor. Finally, similarity analysis was conducted using the Connectivity Map (CMap) profiles to predict a group of small molecules in GC treatment.

RESULTS

A total of 394 DEGs and 31 DEMs were identified after analysis of pre- and post-treatment samples of clinical responders to CF therapy. TM9SF4, hsa-miR-185-5p, and hsa-miR-145-5p were found to be critical in the miRNA-mRNA regulatory network. The DEGs were found to be mainly enriched in the processes of ribonucleoprotein complex assembly, catalytic activity acting on RNA, mitochondrial matrix, and thermogenesis. The DEMs were predominantly found to be involved in single-stranded RNA binding and endoplasmic reticulum lumen. HDAC5, DDX17, ILF3, and SDHC were identified as hub genes in the PPI network. Of these, HDAC5, DDX17, and ILF3 were found to be closely related to the overall survival of GC patients. DisNor identified the first neighbors of the key genes. Furthermore, CMap profiles predicted a group of small molecules, including several histone deacetylase inhibitors (HDACIs), menadione, and mibefradil, which could serve as promising therapeutic agents to reverse acquired resistance to CF therapy.

CONCLUSIONS

Our findings reveal new targets and alternative therapies to overcome the acquired resistance of GC patients to CF treatment.

The multifaceted functions of RNA helicases in the adaptive cellular response to hypoxia: From mechanisms to therapeutics

Hypoxia is a hallmark of cancer. Hypoxia-inducible factor (HIF), a master player for sensing and adapting to hypoxia, profoundly influences genome instability, tumor progression and metastasis, metabolic reprogramming, and resistance to chemotherapies and radiotherapies. High levels and activity of HIF result in poor clinical outcomes in cancer patients. Thus, HIFs provide ideal therapeutic targets for cancers. However, HIF biology is sophisticated, and currently available HIF inhibitors have limited clinical utility owing to their low efficacy or side effects. RNA helicases, which are master players in cellular RNA metabolism, are usually highly expressed in tumors to meet the increased oncoprotein biosynthesis demand. Intriguingly, recent findings provide convincing evidence that RNA helicases are crucial for the adaptive cellular response to hypoxia via a mutual regulation with HIFs. More importantly, some RNA helicase inhibitors may suppress HIF signaling by blocking the translation of HIF-responsive genes. Therefore, RNA helicase inhibitors may work synergistically with HIF inhibitors in cancer to improve treatment efficacy. In this review, we discuss current knowledge of how cells sense and adapt to hypoxia through HIFs. However, our primary focus is on the multiple functions of RNA helicases in the adaptive response to hypoxia. We also highlight how these hypoxia-related RNA helicases can be exploited for anti-cancer therapeutics.

Targeting MUC15 Protein in Cancer: Molecular Mechanisms and Therapeutic Perspectives

MUC15, a member of the mucin family, is a heavily glycosylated transmembrane protein with the primary functions of lubricating surfaces, establishing a selective molecular barrier at the epithelium and mediating signal transduction. Aberrant expression of MUC15 plays a crucial role in the progression of multiple diseases, including malignant tumors. MUC15 has been identified as a tumor suppressor, but current evidence indicate its function as an oncogene in different types of cancers. MUC15 has been shown to be involved in the development of cancer and influence cellular growth, adhesion, invasion, metastasis and immune immunomodulation. However, the precise role of MUC15 in tumour development has not been thoroughly clarified. Here, we systematically summarize the structure and function of MUC15 in cancer, and discuss its potential role in cancer treatment.

The role of miRNA biogenesis and DDX17 in tumorigenesis and cancer stemness

Cancer stemness represents one of the major mechanisms that predispose patients to tumor aggressiveness, metastasis, and treatment resistance. MicroRNA biogenesis is an important process controlling miRNA processing and maturation. Deregulation of miRNA biogenesis can lead to tumorigenesis and cancer stemness. DDX17 is a co-factor of the miRNA microprocessor. Misregulation of DDX17 can be associated with cancer stemness. K63-linked polyubiquitination of DDX17 presents a concerted mechanism of decreased synthesis of stemness-inhibiting miRNAs and increased transcriptional activation of stemness-related gene expression. K63-linked polyubiquitination of HAUSP serves as a scaffold to anchor HIF-1α, CBP, the mediator complex, and the super-elongation complex to enhance HIF-1α-induced gene transcription. Recent progress in RNA modifications shows that RNA N6-methyladenosine (m6A) modification is a crucial mechanism to regulate RNA levels. M6A modification of miRNAs can also be linked to tumorigenesis and cancer stemness. Overall, miRNA biogenesis and K63-linked polyubiquitination of DDX17 play an important role in the induction of cancer stemness. Delineation of the mechanisms and identification of suitable targets may provide new therapeutic options for treatment-resistant cancers.

DDX17 promotes hepatocellular carcinoma progression via inhibiting Klf4 transcriptional activity

DEAD box RNA helicase 17 (DDX17) is a transcriptional regulator of several transcription factors, which is more appreciated than its role in RNA metabolism. However, prognostic value and biofunction of DDX17 in HCC remain unclear. Illuminating the mechanism underlying the regulating HCC progression by DDX17 may contribute to therapeutic strategies. In our study, we report for the first time that DDX17 was overexpressed in HCC specimens by using The Cancer Genome Atlas (TCGA) and immunohistochemistry (IHC) and correlated to clinical pathological characteristics and patients' survival. In vitro, DDX17 was ascertained to alter HCC migratory and invasive capacities after overexpression and knockdown in HCC cell lines. Moreover, by performing co-immunoprecipitation (Co-IP) and GST-pull down assay, the physical association between DDX17 and Klf4 was discovered and validated. Additionally, DDX17 could modulate expressions of Klf4 target genes including E-cadherin, MMP2 by inhibiting the promoter activity. The potent correlation between DDX17 and Klf4 target gene expressions was further appraised by a same set of 30 HCC tissues. Besides, we discovered that DDX17 could not deploy its function in regulating Klf4 target gene expressions and HCC progression in Klf4-depletion condition. Intriguingly, DDX17 failed to interact with Klf4 once the zinc-finger domain was deleted and inhibited the binding of Klf4 on MMP-2 promoter. Collectively, our study enucleates novel mechanism of DDX17-mediated oncogenesis by suppressing the transcriptional activity of Klf4 thus is likely to be a therapeutic target in HCC.

Deciphering GRINA/Lifeguard1: Nuclear Location, Ca2+ Homeostasis and Vesicle Transport

The Glutamate Receptor Ionotropic NMDA-Associated Protein 1 (GRINA) belongs to the Lifeguard family and is involved in calcium homeostasis, which governs key processes, such as cell survival or the release of neurotransmitters. GRINA is mainly associated with membranes of the endoplasmic reticulum, Golgi, endosome, and the cell surface, but its presence in the nucleus has not been explained yet. Here we dissect, with the help of different software tools, the potential roles of GRINA in the cell and how they may be altered in diseases, such as schizophrenia or celiac disease. We describe for the first time that the cytoplasmic N-terminal half of GRINA (which spans a Proline-rich domain) contains a potential DNA-binding sequence, in addition to cleavage target sites and probable PY-nuclear localization sequences, that may enable it to be released from the rest of the protein and enter the nucleus under suitable conditions, where it could participate in the transcription, alternative splicing, and mRNA export of a subset of genes likely involved in lipid and sterol synthesis, ribosome biogenesis, or cell cycle progression. To support these findings, we include additional evidence based on an exhaustive review of the literature and our preliminary data of the protein–protein interaction network of GRINA.

NF-YA transcriptionally activates the expression of SOX2 in cervical cancer stem cells

Roles for SOX2 have been extensively studied in several types of cancer, including colorectal cancer, glioblastoma and breast cancer, with particular emphasis placed on the roles of SOX2 in cancer stem cell. Our previous study identified SOX2 as a marker in cervical cancer stem cells driven by a full promoter element of SOX2 EGFP reporter. Here, dual-luciferase reporter and mutagenesis analyses were employed, identifying key cis-elements in the SOX2 promoter, including binding sites for SOX2, OCT4 and NF-YA factors in SOX2 promoter. Mutagenesis analysis provided additional evidence to show that one high affinity-binding domain CCAAT box was precisely recognized and bound by the transcription factor NF-YA. Furthermore, overexpression of NF-YA in primitive cervical cancer cells SiHa and C33A significantly activated the transcription and the protein expression of SOX2. Collectively, our data identified NF-YA box CCAAT as a key cis-element in the SOX2 promoter, suggesting that NF-YA is a potent cellular regulator in the maintenance of SOX2-positive cervical cancer stem cell by specific transcriptional activation of SOX2.

Functions of DEAD box RNA helicases DDX5 and DDX17 in chromatin organization and transcriptional regulation

RNA helicases DDX5 and DDX17 are multitasking proteins that regulate gene expression in different biological contexts through diverse activities. Special attention has long been paid to their function as coregulators of transcription factors, providing insight about their functional association with a number of chromatin modifiers and remodelers. However, to date, the variety of described mechanisms has made it difficult to understand precisely how these proteins work at the molecular level, and the contribution of their ATPase domain to these mechanisms remains unclear as well. In light of their association with long noncoding RNAs that are key epigenetic regulators, an emerging view is that DDX5 and DDX17 may act through modulating the activity of various ribonucleoprotein complexes that could ensure their targeting to specific chromatin loci. This review will comprehensively describe the current knowledge on these different mechanisms. We will also discuss the potential roles of DDX5 and DDX17 on the 3D chromatin organization and how these could impact gene expression at the transcriptional and post-transcriptional levels.

DEAD-box helicase 27 plays a tumor-promoter role by regulating the stem cell-like activity of human colorectal cancer cells

Background

Cancer stem cells (CSCs) are responsible for all important characteristics of tumors. DEAD-box helicase 27 (DDX27) is a member of the DEAD-box RNA helicase family, and there have been only a few studies on DDX27 function in cancer cells. This study is aimed at exploring whether DDX27 has any relation to tumorigenesis of colorectal cancer (CRC) and elucidating the potential mechanism.

Methods

Data from Catalog Of Somatic Mutations In Cancer, Gene Expression Omnibus, and The Cancer Genome Atlas databases reveal that DDX27 is overexpressed in CRC tissues. qRT-PCR and Western blots were used to evaluate the expression level of DDX27 in 40 paired clinical CRC samples. DDX27 was knockdown in HT29 and HCT116 cell line with shRNA. Then CCK-8, colony formation assay and flow cytometry assay were performed to examine proliferative ability, cell cycle and sensitivity to 5-fluorouracil. Sphere-formation assay and in vivo subcutaneous tumor-formation assay were used to assess self-renewal in vitro and vivo as well as the tumor-initiating potential.

Results

DDX27 is upregulated in CRC tissues and downregulation of DDX27 inhibits proliferation of colorectal cancer cell and promotes sensitivity to 5-fluorouracil. Downregulation of DDX27 can downregulate the gene expression of known CSC markers in CRC cells, inhibit sphere-formation ability, and promote colonosphere differentiation. Downregulation of DDX27 in CSCs can decrease the tumor-initiating ability of CRC cells in vivo.

Conclusion

DDX27 may play a tumorpromoter role of CRC by regulating the stem cell-like activity of CRC cells.

SOX2 recruits KLF4 to regulate nasopharyngeal carcinoma proliferation via PI3K/AKT signaling

SOX2 is a transcription factor that contributes to transcription modification and cancer, but the mechanism by which SOX2 regulates nasopharyngeal carcinoma cell proliferation is not well understood. Here, we identify a SOX2 signaling pathway that facilitates nasopharyngeal carcinoma, where it is upregulated. SOX2 expression was associated with nasopharyngeal carcinoma patient survival. SOX2 knockdown inhibited cell proliferation, colony formation, and tumorigenesis in an subcutaneous mouse xenograft model system. Six hundred and ninety-nine candidate SOX2 downstream dysregulated genes were identified in nasopharyngeal carcinoma cells through cDNA microarray analysis. SOX2 recruited the nuclear transcription factor KLF4 to bind to the PIK3CA promoter upregulate PIK3CA expression, acting to enhance PI3K/AKT signaling and tumorigenesis by upregulating PIK3CA expression. Besides, overexpressing activated AKT or PIK3CA rescued the growth inhibition of cells due to SOX2 knockdown. Together, our study suggest that SOX2 exhibits oncogenic properties and may be a reliable molecular biomarker in nasopharyngeal carcinoma. Targeting SOX2 might be a promising treatment strategy for nasopharyngeal carcinoma treatment.

Phosphorylation of Sox2 at Threonine 116 is a Potential Marker to Identify a Subset of Breast Cancer Cells with High Tumorigenecity and Stem-Like Features

We have previously identified a novel phenotypic dichotomy in breast cancer (BC) based on the response to a SRR2 (Sox2 regulatory region 2) reporter, with reporter responsive (RR) cells being more tumorigenic/stem-like than reporter unresponsive (RU) cells. Since the expression level of Sox2 is comparable between the two cell subsets, we hypothesized that post-translational modifications of Sox2 contribute to their differential reporter response and phenotypic differences. By liquid chromatography-mass spectrometry, we found Sox2 to be phosphorylated in RR but not RU cells. Threonine 116 is an important phosphorylation site, since transfection of the T116A mutant into RR cells significantly decreased the SRR2 reporter luciferase activity and the RR-associated phenotype. Oxidative stress-induced conversion of RU into RR cells was accompanied by Sox2 phosphorylation at T116 and increased Sox2-DNA binding. In a cohort of BC, we found significant correlations between the proportion of tumor cells immuno-reactive with anti-phosphorylated Sox2^T116 and a high tumor grade (p = 0.006), vascular invasion (p = 0.001) and estrogen receptor expression (p = 0.032). In conclusion, our data suggests that phosphorylation of Sox2^T116 contributes to the tumorigenic/stem-like features in RR cells. Detection of phospho-Sox2^T116 may be useful in identifying a small subset of tumor cells carrying stem-like/tumorigenic features in BC.

Extracellular superoxide dismutase and its role in cancer

Reactive oxygen species (ROS) are increasingly recognized as critical determinants of cellular signaling and a strict balance of ROS levels must be maintained to ensure proper cellular function and survival. Notably, ROS is increased in cancer cells. The superoxide dismutase family plays an essential physiological role in mitigating deleterious effects of ROS. Due to the compartmentalization of ROS signaling, EcSOD, the only superoxide dismutase in the extracellular space, has unique characteristics and functions in cellular signal transduction. In comparison to the other two intracellular SODs, EcSOD is a relatively new comer in terms of its tumor suppressive role in cancer and the mechanisms involved are less well understood. Nevertheless, the degree of differential expression of this extracellular antioxidant in cancer versus normal cells/tissues is more pronounced and prevalent than the other SODs. A significant association of low EcSOD expression with reduced cancer patient survival further suggests that loss of extracellular redox regulation promotes a conducive microenvironment that favors cancer progression. The vast array of mechanisms reported in mediating deregulation of EcSOD expression, function, and cellular distribution also supports that loss of this extracellular antioxidant provides a selective advantage to cancer cells. Moreover, overexpression of EcSOD inhibits tumor growth and metastasis, indicating a role as a tumor suppressor. This review focuses on the current understanding of the mechanisms of deregulation and tumor suppressive function of EcSOD in cancer.

Pediatric dilated cardiomyopathy hearts display a unique gene expression profile

Our previous work showed myocellular differences in pediatric and adult dilated cardiomyopathy (DCM). However, a thorough characterization of the molecular pathways involved in pediatric DCM does not exist, limiting the development of age-specific therapies. To characterize this patient population, we investigated the transcriptome profile of pediatric patients. RNA-Seq from 7 DCM and 7 nonfailing (NF) explanted age-matched pediatric left ventricles (LV) was performed. Changes in gene expression were confirmed by real-time PCR (RT-PCR) in 36 DCM and 21 NF pediatric hearts and in 20 DCM and 10 NF adult hearts. The degree of myocyte hypertrophy was investigated in 4 DCM and 7 NF pediatric hearts and in 4 DCM and 9 NF adult hearts. Changes in gene expression in response to pluripotency-inducing factors were investigated in neonatal rat ventricular myocytes (NRVMs). Transcriptome analysis identified a gene expression profile in children compared with adults with DCM. Additionally, myocyte hypertrophy was not observed in pediatric hearts but was present in adult hearts. Furthermore, treatment of NRVMs with pluripotency-inducing factors recapitulated changes in gene expression observed in the pediatric DCM heart. Pediatric DCM is characterized by unique changes in gene expression that suggest maintenance of an undifferentiated state.

Wanted DEAD/H or Alive: Helicases Winding Up in Cancers

Cancer is one of the most studied areas of human biology over the past century. Despite having attracted much attention, hype, and investments, the search to find a cure for cancer remains an uphill battle. Recent discoveries that challenged the central dogma of molecular biology not only further increase the complexity but also demonstrate how various types of noncoding RNAs such as microRNA and long noncoding RNA, as well as their related processes such as RNA editing, are important in regulating gene expression. Parallel to this aspect, an increasing number of reports have focused on a family of proteins known as DEAD/H-box helicases involved in RNA metabolism, regulation of long and short noncoding RNAs, and novel roles as "editing helicases" and their association with cancers. This review summarizes recent findings on the roles of RNA helicases in various cancers, which are broadly classified into adult solid tumors, childhood solid tumors, leukemia, and cancer stem cells. The potential small molecule inhibitors of helicases and their therapeutic value are also discussed. In addition, analyzing next-generation sequencing data obtained from public portals and reviewing existing literature, we provide new insights on the potential of DEAD/H-box helicases to act as pharmacological drug targets in cancers.