DEAD/H-box helicase 11 is transcriptionally activated by Yin Yang-1 and accelerates oral squamous cell carcinoma progression.

Oral squamous cell carcinoma (OSCC) is the most common oral malignancy. DEAD/H-box helicase 11 (DDX11), a DNA helicase, has been implicated in the progression of several cancers. Yet, the precise function of DDX11 in OSCC is poorly understood. The DDX11 expression in OSCC cells and normal oral keratinocytes was evaluated in the Gene Expression Omnibus database (GSE146483 and GSE31853). SCC-4 and CAL-27 cells expressing doxycycline-inducible DDX11 or DDX11 shRNA were generated by lentiviral infection. The role of DDX11 in OSCC cells was determined by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay, colony formation assay, flow cytometry assay, TUNEL staining, and western blot. The effects of DDX11 on tumor growth were explored in a xenograft nude mouse model. The relationship between DDX11 and transcription factor Yin Yang-1 (YY1) was researched using the dual luciferase report assay and chromatin immunoprecipitation assay. DDX11 expression was significantly upregulated in OSCC cells. Knockdown of DDX11 inhibited cell proliferation, induced cell cycle arrest, and suppressed PI3K-AKT pathway, while DDX11 overexpression showed opposite effects. The number of apoptotic cells was increased in DDX11 silenced cells. DDX11 upregulation or knockdown accelerated or suppressed tumor growth in vivo, respectively. Moreover, the YY1 bound and activated the DDX11 promoter, resulting in increasing DDX11 expression. Forced expression DDX11 reversed the anticancer effects of YY1 silencing on OSCC cells. DDX11 has tumor-promoting function in OSCC and is transcriptionally regulated by YY1, indicating that DDX11 may serve as a potential target for the OSCC treatment.

ATPR induces acute promyelocytic leukemia cells differentiation and cycle arrest via the lncRNA CONCR/DDX11/PML-RARα signaling axis.

Acute promyelocytic leukemia (APL) is a type of acute myeloid leukemia (AML) with a high mortality rate, and the production of PML-RARα fusion protein is the cause of its pathogenesis. Our group has synthesized a novel compound, 4-amino-2-trifluoromethyl-phenyl retinate (ATPR), by structural modification of All-trans retinoic acid (ATRA), which has strong cell differentiation-inducing effects and inhibits the expression of PML-RARα. In this study, acute promyelocytic leukemia NB4 cells before and after ATPR induction were analyzed by whole transcriptome microarray, and the expression of lncRNA CONCR was found to be significantly downregulated. The role of CONCR in ATPR-induced cell differentiation and cycle arrest was explored through overexpression and silencing of CONCR. And then the database was used to predict that CONCR may bind to DEAD/H-Box Helicase 11 (DDX11) protein to further explore the role of CONCR binding to DDX11. The results showed that ATPR could reduce the expression of CONCR, and overexpression of CONCR could reverse the ATPR-induced cell differentiation and cycle blocking effect, and conversely silencing of CONCR could promote this effect. RNA immunoprecipitation (RIP) experiments showed that CONCR could bind to DDX11, the protein expression levels of DDX11 and PML-RARα were elevated after overexpression of CONCR. These results suggest that ATPR can regulate the expression of DDX11 through CONCR to affect the expression of PML-RARα fusion protein, which in turn induces the differentiation and maturation of APL cells.

Mapping of DDX11 genetic interactions defines sister chromatid cohesion as the major dependency.

DDX11/Chl1R is a conserved DNA helicase with roles in genome maintenance, DNA replication, and chromatid cohesion. Loss of DDX11 in humans leads to the rare cohesinopathy Warsaw breakage syndrome. DDX11 has also been implicated in human cancer where it has been proposed to have an oncogenic role and possibly to constitute a therapeutic target. Given the multiple roles of DDX11 in genome stability and its potential as an anticancer target, we set out to define a complete genetic interaction profile of DDX11 loss in human cell lines. Screening the human genome with clustered regularly interspaced short palindromic repeats (CRISPR) guide RNA drop out screens in DDX11-wildtype (WT) or DDX11-deficient cells revealed a strong enrichment of genes with functions related to sister chromatid cohesion. We confirm synthetic lethal relationships between DDX11 and the tumor suppressor cohesin subunit STAG2, which is frequently mutated in several cancer types and the kinase HASPIN. This screen highlights the importance of cohesion in cells lacking DDX11 and suggests DDX11 may be a therapeutic target for tumors with mutations in STAG2.

DDX11-AS1 modulates DNA damage repair to enhance paclitaxel resistance of lung adenocarcinoma cells.

Aim: To investigate the influence of DDX11-AS1 on paclitaxel (PTX) resistance in lung adenocarcinoma (LUAD). Methods: LncRNA expression and functional enrichment analyses were processed via bioinformatics methods. DDX11-AS1 expression was detected via quantitative real-time PCR. Cell counting kit-8, colony formation, flow cytometry and comet assays were manipulated to measure cell proliferation, apoptosis, cell cycle and DNA damage repair, respectively. Western blot was used to assess DNA damage-related protein expression. Results: DDX11-AS1 was in a high expression status in LUAD, and could promote LUAD cell proliferation and PTX resistance, while suppressing cell apoptosis. DNA damage repairing ability was also modulated by the change of DDX11-AS1 expression. Conclusion: LncRNA DDX11-AS1 promotes DNA damage repair to enhance PTX resistance in LUAD.

Síndrome de rotura de Varsovia: una causa de microcefalia congénita y sordera neurosensorial / Warsaw breakage syndrome: an etiology for congenital microcephaly and sensorineural deafness

Introducción: El síndrome de rotura de Varsovia es una alteración genética muy poco frecuente originada por variantes patógenas bialélicas en el gen DDX11, implicado en la cohesión de las cromátidas hermanas, que pertenece al grupo de las cohesinopatías. Clínicamente se caracteriza por retraso del crecimiento, microcefalia y sordera neurosensorial, con otras manifestaciones menos frecuentes: dismorfia facial, anomalías esqueléticas, cardíacas, cutáneas y genitourinarias. Caso clínico: Presentamos a un varón con las manifestaciones cardinales del síndrome: bajo peso en el nacimiento, microcefalia congénita grave y sordera neurosensorial con agenesia de los nervios cocleares. También presenta cardiopatía, hipospadias, criptorquidia, anomalía cutánea y pies planos. En el exoma se han identificado dos variantes en heterocigosis probablemente patógenas en el gen DDX11, c.1403dup; p.(Ser469Valfs*32) y c.2371C>T; p.(Arg791Trp), heredadas cada una de un progenitor. Conclusión: Revisamos a los 23 pacientes descritos con el síndrome en la bibliografía, tanto desde el punto de vista clínico como desde el genético. Analizamos el significado etiopatógeno de las variantes de nuestro caso basándonos en los datos moleculares y las funciones celulares de DDX11 de los estudios publicados. Debido al solapamiento clínico con los síndromes con rotura cromosómica y las cohesinopatías, debemos realizar el diagnóstico diferencial con estas entidades, fundamentalmente la anemia de Fanconi, el síndrome de rotura de Nijmegen, el síndrome de Cornelia de Lange y el síndrome de Roberts. En la práctica clínica, debemos sospechar este síndrome en el período neonatal en un paciente con retraso del crecimiento intrauterino, microcefalia grave y sordera neurosensorial.(AU)

Introduction: Warsaw breakage syndrome is a very rare genetic disorder due to biallelic pathogenic variants in DDX11 gene, with a role in the sister chromatid cohesion process, and classified in the cohesinophaties group. It is characterized by the clinical triad of growth restriction, microcephaly and sensorineural deafness. Additional, but less frequent features, are facial dysmorphism, and skeletal, heart, skin and genitourinary anomalies. Case report: We report a boy with the cardinal features of the syndrome: prenatal growth restriction, severe congenital microcephaly, and sensorineural deafness with cochlear nerves agenesis. He also has a cardiac anomaly, hypospadias, cryptorchidism, skin abnormality, and pes planus. The exome yielded two heterozygous likely pathogenic variants in the DDX11 gene, c.1403dup; p.(Ser469Valfs*32) and c.2371C>T; p.(Arg791Trp), inherited in trans from the parents. Conclusion: We review the clinical and genetic data of the 23 reported cases with the syndrome in the literature and analyze the etiopathogenic interpretation of our case variants based on the molecular and cellular functions of DDX11 described. Due to the clinical overlap with the chromosomal breakage syndromes and cohesinopathies we must make the differential diagnosis with these entities, overall, with Fanconi anemia, Nijmegen breakage syndrome, Cornelia de Lange syndrome and Roberts syndrome. In clinical practice we must think in Warsaw breakage syndrome in the neonatal period in a patient with intrauterine growth restriction, severe microcephaly, and sensorineural deafness.(AU)

LncRNA DDX11-AS1 Promotes Chemoresistance through LIN28A-Mediated ATG12 mRNA Stabilization in Breast Cancer.

INTRODUCTION: During breast cancer chemotherapy, the chemoresistance that frequently accompanies the treatment has become a big challenge. Long noncoding RNAs (LncRNAs) have been related to the development of chemoresistance in multiple cancer types. LncRNA DDX11-AS1 has shown a carcinogenic role in lung and colorectal cancer and was reported to enhance oxaliplatin resistance in gastric cancer and Taxol insensitivity in esophageal cancer. But its role in breast cancer chemotherapy drug resistance remains unknown. This study aimed to investigate the function and mechanism of lncRNA DDX11-AS1 in breast cancer chemoresistance. METHODS: The relationship between DDX11-AS1 and adriamycin (ADR) resistance was confirmed by qPCR, cell viability tests, and survival analysis. Then, RNA immunoprecipitation was conducted to evaluate the interaction between DDX11-AS1 and RNA-binding protein LIN28A. The regulation effect of LIN28A on autophagy-related genes ATG7 or ATG12 was detected by RNA stability assay and Western blot. Their correlation analysis was evaluated in GEO datasets and further validated by immunohistochemical results. The clinical significance of DDX11-AS1, ATG7, or ATG12 was evaluated by Kaplan-Meier Plotter analysis. RESULTS: Here, we reported DDX11-AS1 was significantly upregulated in chemoresistant breast cancer cells and overexpression of DDX11-AS1 promoted ADR resistance in breast cancer. LIN28A could interact with DDX11-AS1 and was involved in DDX11-AS1-mediated ADR resistance. Interfering with LIN28A reversed DDX11-AS1-induced ADR resistance. LIN28A could increase the protein level of ATG7 and ATG12 by increasing their mRNA stability. Survival analysis showed that ATG12 expression level was negatively correlated with the prognosis of breast cancer patients. CONCLUSION: This study clarifies the role of DDX11-AS1 in breast cancer chemoresistance and revealed a new mechanism, that is, interacting with LIN28A to stabilize ATG7 and ATG12 and jointly promote chemorefractory. These findings warrant further in vivo investigations to study DDX11-AS1 as a potential target to overcome chemoresistance.

Pan-cancer surveys indicate cell cycle-related roles of primate-specific genes in tumors and embryonic cerebrum.

BACKGROUND: Despite having been extensively studied, it remains largely unclear why humans bear a particularly high risk of cancer. The antagonistic pleiotropy hypothesis predicts that primate-specific genes (PSGs) tend to promote tumorigenesis, while the molecular atavism hypothesis predicts that PSGs involved in tumors may represent recently derived duplicates of unicellular genes. However, these predictions have not been tested. RESULTS: By taking advantage of pan-cancer genomic data, we find the upregulation of PSGs across 13 cancer types, which is facilitated by copy-number gain and promoter hypomethylation. Meta-analyses indicate that upregulated PSGs (uPSGs) tend to promote tumorigenesis and to play cell cycle-related roles. The cell cycle-related uPSGs predominantly represent derived duplicates of unicellular genes. We prioritize 15 uPSGs and perform an in-depth analysis of one unicellular gene-derived duplicate involved in the cell cycle, DDX11. Genome-wide screening data and knockdown experiments demonstrate that DDX11 is broadly essential across cancer cell lines. Importantly, non-neutral amino acid substitution patterns and increased expression indicate that DDX11 has been under positive selection. Finally, we find that cell cycle-related uPSGs are also preferentially upregulated in the highly proliferative embryonic cerebrum. CONCLUSIONS: Consistent with the predictions of the atavism and antagonistic pleiotropy hypotheses, primate-specific genes, especially those PSGs derived from cell cycle-related genes that emerged in unicellular ancestors, contribute to the early proliferation of the human cerebrum at the cost of hitchhiking by similarly highly proliferative cancer cells.

Long non-coding RNA DDX11-AS1 promotes the proliferation and migration of glioma cells by combining with HNRNPC.

Glioma is a malignant tumor of the central nervous system with complex pathogenesis, difficult operation, and a high postoperative recurrence rate. At present, there is still a lack of effective treatment. Long non-coding RNA DDX11 antisense RNA 1 (DDX11-AS1) has been shown to promote tumor development, such as hepatocellular carcinoma, esophageal cancer, etc. However, its molecular mechanism in glioma is poorly understood. In this study, we found that the expression of DDX11-AS1 was elevated in glioma tissues, and patients with high expression of DDX11-AS1 had poor prognosis. DDX11-AS1 was a potential prognostic marker. Functionally, DDX11-AS1 promoted glioma cell proliferation and migration. Mechanistically, DDX11-AS1 interacted with RNA-binding protein heterogeneous nuclear ribonucleoprotein C (HNRNPC) to promote Wnt/ß-catenin and AKT pathways and the epithelial-mesenchymal transition process. In summary, our study manifests that the DDX11-AS1/HNRNPC axis may play a vital part in the occurrence and development of glioma, which provides new ideas and therapeutic targets for the diagnosis, treatment, and prognosis of glioma.

Knockdown of long non­coding RNA DDX11­AS1 inhibits the proliferation, migration and paclitaxel resistance of breast cancer cells by upregulating microRNA­497 expression.

Drug resistance is a major problem to overcome in the treatment of cancer; therefore, identifying therapeutic targets for drug resistance is a point of focus in the field of cancer research. Long non­coding RNAs (lncRNAs) and microRNAs (miRs) not only affect gene expression regulation during cell proliferation, but also have several potential roles in the drug resistance of malignant tumors. Reverse transcription­quantitative PCR was used to detect the expression levels of DDX11 antisense RNA 1 (DDX11­AS1) and miR­497 in MCF­7 and MDA­MB­231 cells. Cell transfection techniques were used to interfere with the expression levels of DDX11­AS1 and miR­497. Cell Counting Kit­8 and MTT assays were used to detect cell viability. A colony formation assay was used to detect cell proliferation. Wound­healing and Transwell assays were performed to measure the levels of cell migration and invasion. Western blotting was used to analyze the expression levels of migration­associated proteins, and immunofluorescence and western blotting were used to determine the expression levels of the epithelial­mesenchymal transition­related proteins E­cadherin and N­cadherin, respectively. A luciferase reporter gene assay was used to verify the targeted binding of DDX11­AS1 and miR­497. The present study demonstrated that the expression levels of lncRNA DDX11­AS1 were markedly increased in paclitaxel (PTX)­resistant breast cancer cell lines. By contrast, knockdown of DDX11­AS1 expression inhibited PTX resistance of breast cancer cells, and suppressed the proliferation, invasion and migration of breast cancer cells, which was achieved via upregulation of miR­497 expression. In conclusion, knockdown of lncRNA DDX11­AS1 could inhibit the proliferation, migration and PTX resistance of breast cancer cells by upregulating miR­497 expression.

LncRNA DDX11 antisense RNA 1 promotes EMT process of esophageal squamous cell carcinoma by sponging miR-30d-5p to regulate SNAI1/ZEB2 expression and Wnt/ß-catenin pathway.

LncRNA DDX11 antisense RNA 1 (DDX11-AS1) is recognized as having an imperative oncogenic role in different types of human cancer. Nevertheless, the functions, as well as the basic mechanisms of DDX11-AS1 in the EMT process of esophageal squamous cell carcinoma (ESCC), are yet to be clarified. In this research, high DDX11-AS1 expression was detected in ESCC cells as well as tissues and was linked to the poor prognosis of patients with ESCC. DDX11-AS1 promoted cell proliferation, migration, invasion ability and epithelial mesenchymal transition (EMT) process in vitro. Mechanistic analysis depicted that DDX11-AS1 may function as a ceRNA through sponging miR-30d-5p to upregulate the expression of SNAI1 and ZEB2. Meanwhile, overexpression of DDX11-AS1 might cause the activation of the Wnt/ß-catenin signaling pathway via targeting miR-30d-5p. On the whole, the findings of this research illustrate that DDX11-AS1 may act as an EMT-related lncRNA to advance ESCC progression through sponging miR-30d-5p to regulate SNAI1/ZEB2 expression and activate the Wnt/ß-catenin pathway, which indicates that it might serve as a probable therapeutic target for ESCC.

Vertebrate CTF18 and DDX11 essential function in cohesion is bypassed by preventing WAPL-mediated cohesin release.

The alternative PCNA loader containing CTF18-DCC1-CTF8 facilitates sister chromatid cohesion (SCC) by poorly defined mechanisms. Here we found that in DT40 cells, CTF18 acts complementarily with the Warsaw breakage syndrome DDX11 helicase in mediating SCC and proliferation. We uncover that the lethality and cohesion defects of ctf18 ddx11 mutants are associated with reduced levels of chromatin-bound cohesin and rescued by depletion of WAPL, a cohesin-removal factor. On the contrary, high levels of ESCO1/2 acetyltransferases that acetylate cohesin to establish SCC do not rescue ctf18 ddx11 phenotypes. Notably, the tight proximity of sister centromeres and increased anaphase bridges characteristic of WAPL-depleted cells are abrogated by loss of both CTF18 and DDX11 The results reveal that vertebrate CTF18 and DDX11 collaborate to provide sufficient amounts of chromatin-loaded cohesin available for SCC generation in the presence of WAPL-mediated cohesin-unloading activity. This process modulates chromosome structure and is essential for cellular proliferation in vertebrates.

Landscape analysis of lncRNAs shows that DDX11-AS1 promotes cell-cycle progression in liver cancer through the PARP1/p53 axis.

Although long non-coding RNAs (lncRNAs) play important roles in tumorigenesis, the underlying mechanisms are unclear. Transcriptomic analysis of 33 hepatocellular carcinoma (HCC) samples revealed that the most enriched pathway for differentially expressed genes was related to the cell cycle process, where DDX11-AS1 is the most significant lncRNA. Upregulation of DDX11-AS1 expression through demethylation was significantly associated with a poor prognosis. Further mechanistic studies revealed that DDX11-AS1 promoted the growth of HCC by interacting with PARP1 through attenuating its binding to p53, leading to downregulated expression of p53 for inhibiting the transcription of downstream genes such as p21. Knockdown of DDX11-AS1 expression in xenograft mice using anti-DDX11-AS1 oligonucleotide suppressed liver tumor proliferation. These findings indicate that DDX11-AS1 plays a role in the development of liver cancer by affecting the cell cycle.

Long non-coding RNA DDX11-AS1 promotes esophageal carcinoma cell proliferation and migration through regulating the miR-514b-3p/RBX1 axis.

Esophageal carcinoma (ESCA) is one of the most aggressive malignancies with extremely high morbidity and mortality. At present, limited advancement in ESCA treatment has achieved. Therefore, it is urgent to explore the pathogenesis and progression mechanism of ESCA to provide the basis for the formulation of novel therapeutic strategies. Previous studies have found that long non-coding RNA (lncRNA) DDX11-AS1 expression enhances the paclitaxel resistance of ESCA cells. However, the mechanisms underlying the drug resistance conferred by lncRNA DDX11-AS1 in ESCA remains to be elucidated. Our research aims to clarify the role and mechanism of lncRNA DDX11-AS1 in regulating the progression of ESCA. We found that the expression of lncRNA DDX11-AS1 in ESCA tissues and cell lines was significantly upregulated. Subsequently, silencing lncRNA DDX11-AS1 significantly inhibited the proliferation, migration and invasion of ESCA cells, and induced the level of cell apoptosis. In terms of mechanism, our data showed that miR-514b-3p/RING box protein 1 (RBX1) axis played a crucial role in the oncogenic function of lncRNA DDX11-AS1. LncRNA DDX11-AS1 expression impaired the inhibitory function of miR-514b-3p on RBX1 through sponging effect. Taken together, our data support the notion that lncRNA DDX11-AS1 promotes the progression of ESCA through miR-514b-3p/RBX1 axis. Our research uncovers the novel regulatory role of lncRNA DDX11-AS1 in ESCA and lays a theoretical basis for developing novel treatment strategy of ESCA.

Expression of DDX11 and DNM1L at the 12p11 Locus Modulates Systemic Lupus Erythematosus Susceptibility.

OBJECTIVES: This study employed genetic and functional analyses using OASIS meta-analysis of multiple existing GWAS and gene-expression datasets to identify novel SLE genes. METHODS: Four hundred and ten genes were mapped using SNIPPER to 30 SLE GWAS loci and investigated for expression in three SLE GEO-datasets and the Cordoba GSE50395-dataset. Blood eQTL for significant SNPs in SLE loci and STRING for functional pathways of differentially expressed genes were used. Confirmatory qPCR on SLE monocytes was performed. The entire 12p11 locus was investigated for genetic association using two additional GWAS. Expression of 150 genes at this locus was assessed. Based on this significance, qPCRs for DNM1L and KRAS were performed. RESULTS: Fifty genes were differentially expressed in at least two SLE GEO-datasets, with all probes directionally aligned. DDX11, an RNA helicase involved in genome stability, was downregulated in both GEO and Cordoba datasets. The most significant SNP, rs3741869 in OASIS locus 12p11.21, containing DDX11, was a cis-eQTL regulating DDX11 expression. DDX11 was found repressed. The entire 12p11 locus showed three association peaks. Gene expression in GEO datasets identified DNM1L and KRAS, besides DDX11. Confirmatory qPCR validated DNM1L as an SLE susceptibility gene. DDX11, DNM1L and KRAS interact with each other and multiple known SLE genes including STAT1/STAT4 and major components of IFN-dependent gene expression, and are responsible for signal transduction of cytokines, hormones, and growth-factors, deregulation of which is involved in SLE-development. CONCLUSION: A genomic convergence approach with OASIS analysis of multiple GWAS and expression datasets identified DDX11 and DNM1L as novel SLE-genes, the expression of which is altered in monocytes from SLE patients. This study lays the foundation for understanding the pathogenic involvement of DDX11 and DNM1L in SLE by identifying them using a systems-biology approach, while the 12p11 locus harboring these genes was previously missed by four independent GWAS.

The DEAD/DEAH Box Helicase, DDX11, Is Essential for the Survival of Advanced Clear Cell Renal Cell Carcinoma and Is a Determinant of PARP Inhibitor Sensitivity.

Genes associated with the DEAD-box helicase DDX11 are significant biomarkers of aggressive renal cell carcinoma (RCC), but their molecular function is poorly understood. We analyzed the molecular pathways through which DDX11 is involved in RCC cell survival and poly (ADP-ribose) polymerase (PARP) inhibitor sensitivity. Immunohistochemistry and immunoblotting determined DDX11 expression in normal kidney tissues, benign renal tumors, and RCC tissues and cell lines. Quantitative polymerase chain reaction validated the downregulation of DDX11 in response to transfection with DDX11-specific small interfering RNA. Proliferation analysis and apoptosis assays were performed to determine the impact of DDX11 knockdown on RCC cells, and the relevant effects of sunitinib, olaparib, and sunitinib plus olaparib were evaluated. DDX11 was upregulated in high-grade, advanced RCC compared to low-grade, localized RCC, and DDX11 was not expressed in normal kidney tissues or benign renal tumors. DDX11 knockdown resulted in the inhibition of RCC cell proliferation, segregation defects, and rapid apoptosis. DDX11-deficient RCC cells exhibited significantly increased sensitivity to olaparib compared to sunitinib alone or sunitinib plus olaparib combination treatments. Moreover, DDX11 could determine PARP inhibitor sensitivity in RCC. DDX11 could serve as a novel therapeutic biomarker for RCC patients who are refractory to conventional targeted therapies and immunotherapies.

The Genome Stability Maintenance DNA Helicase DDX11 and Its Role in Cancer.

DDX11/ChlR1 is a super-family two iron-sulfur cluster containing DNA helicase with roles in DNA replication and sister chromatid cohesion establishment, and general chromosome architecture. Bi-allelic mutations of the DDX11 gene cause a rare hereditary disease, named Warsaw breakage syndrome, characterized by a complex spectrum of clinical manifestations (pre- and post-natal growth defects, microcephaly, intellectual disability, heart anomalies and sister chromatid cohesion loss at cellular level) in accordance with the multifaceted, not yet fully understood, physiological functions of this DNA helicase. In the last few years, a possible role of DDX11 in the onset and progression of many cancers is emerging. Herein we summarize the results of recent studies, carried out either in tumoral cell lines or in xenograft cancer mouse models, suggesting that DDX11 may have an oncogenic role. The potential of DDX11 DNA helicase as a pharmacological target for novel anti-cancer therapeutic interventions, as inferred from these latest developments, is also discussed.

DDX11 loss causes replication stress and pharmacologically exploitable DNA repair defects.

DDX11 encodes an iron-sulfur cluster DNA helicase required for development, mutated, and overexpressed in cancers. Here, we show that loss of DDX11 causes replication stress and sensitizes cancer cells to DNA damaging agents, including poly ADP ribose polymerase (PARP) inhibitors and platinum drugs. We find that DDX11 helicase activity prevents chemotherapy drug hypersensitivity and accumulation of DNA damage. Mechanistically, DDX11 acts downstream of 53BP1 to mediate homology-directed repair and RAD51 focus formation in manners nonredundant with BRCA1 and BRCA2. As a result, DDX11 down-regulation aggravates the chemotherapeutic sensitivity of BRCA1/2-mutated cancers and resensitizes chemotherapy drug-resistant BRCA1/2-mutated cancer cells that regained homologous recombination proficiency. The results further indicate that DDX11 facilitates recombination repair by assisting double strand break resection and the loading of both RPA and RAD51 on single-stranded DNA substrates. We propose DDX11 as a potential target in cancers by creating pharmacologically exploitable DNA repair vulnerabilities.

Silenced lncRNA DDX11-AS1 or up-regulated microRNA-34a-3p inhibits malignant phenotypes of hepatocellular carcinoma cells via suppression of TRAF5.

BACKGROUND: Studies have discussed long noncoding RNA DDX11-AS1 (DDX11-AS1)-mediated downstream mechanism in hepatocellular carcinoma (HCC). The goal of this study was to investigate the regulatory mechanism of DDX11-AS1-mediated microRNA-34a-3p (miR-34a-3p)/tumor necrosis factor receptor-associated factor 5 (TRAF5) axis on HCC cells. METHODS: DDX11-AS1, miR-34a-3p and TRAF5 expression levels in HCC were detected. The correlation of DDX11-AS1, miR-34a-3p and TRAF5 in HCC patients was analyzed by Pearson test. HCC cells were transfected with corresponding plasmid/oligonucleotide, and cell proliferation, migration, invasion, apoptosis and tumor formation ability were detected. Bioinformatics software, dual luciferase report experiment and RNA-pull down experiment analysis were applied to verify the targeting relationship between DDX11-AS1, miR-34a-3p and TRAF5. RESULTS: Elevated DDX11-AS1 and TRAF5 and reduced miR-34a-3p exhibited in HCC. Silenced DDX11-AS1 or up-regulated miR-34a-3p inhibited the proliferation, migration, invasion, promoted apoptosis of HCC cells and repressed the tumor growth in nude mice. In addition, DDX11-AS1 bound to miR-34a-3p to target TRAF5. Silencing TRAF5 or elevating miR-34a-3p expression mitigated up-regulated DDX11-AS1-mediated promotion of tumor growth. CONCLUSION: Silenced DDX11-AS1 or up-regulated miR-34a-3p inhibits HCC cell growth via elevation of TRAF5, which could be of great benefit to find early diagnostic markers for HCC patients.

Role of the DDX11 DNA Helicase in Warsaw Breakage Syndrome Etiology.

Warsaw breakage syndrome (WABS) is a genetic disorder characterized by sister chromatid cohesion defects, growth retardation, microcephaly, hearing loss and other variable clinical manifestations. WABS is due to biallelic mutations of the gene coding for the super-family 2 DNA helicase DDX11/ChlR1, orthologous to the yeast chromosome loss protein 1 (Chl1). WABS is classified in the group of "cohesinopathies", rare hereditary diseases that are caused by mutations in genes coding for subunits of the cohesin complex or protein factors having regulatory roles in the sister chromatid cohesion process. In fact, among the cohesion regulators, an important player is DDX11, which is believed to be important for the functional coupling of DNA synthesis and cohesion establishment at the replication forks. Here, we will review what is known about the molecular and cellular functions of human DDX11 and its role in WABS etiopathogenesis, even in light of recent findings on the role of cohesin and its regulator network in promoting chromatin loop formation and regulating chromatin spatial organization.

Finding underlying genetic mechanisms of two patients with autism spectrum disorder carrying familial apparently balanced chromosomal translocations.

BACKGROUND: Genetic etiologies of autism spectrum disorders (ASD) are complex, and the genetic factors identified so far are very diverse. In complex genetic diseases such as ASD, de novo or inherited chromosomal abnormalities are valuable findings for researchers with respect to identifying the underlying genetic risk factors. With gene mapping studies on these chromosomal abnormalities, dozens of genes have been associated with ASD and other neurodevelopmental genetic diseases. In the present study, we aimed to idenitfy the causative genetic factors in patients with ASD who have an apparently balanced chromosomal translocation in their karyotypes. METHODS: For mapping the broken genes as a result of chromosomal translocations, we performed whole genome DNA sequencing. Chromosomal breakpoints and large DNA copy number variations (CNV) were determined after genome alignment. Identified CNVs and single nucleotide variations (SNV) were evaluated with VCF-BED intersect and Gemini tools, respectively. A targeted resequencing approach was performed on the JMJD1C gene in all of the ASD cohorts (220 patients). For molecular modeling, we used a homology modeling approach via the SWISS-MODEL. RESULTS: We found that there was no contribution of the broken genes or regulator DNA sequences to ASD, whereas the SNVs on the JMJD1C, CNKSR2 and DDX11 genes were the most convincing genetic risk factors for underlying ASD phenotypes. CONCLUSIONS: Genetic etiologies of ASD should be analyzed comprehensively by taking into account of the all chromosomal structural abnormalities and de novo or inherited CNV/SNVs with all possible inheritance patterns.