Integration of RNAi and RNA-seq uncovers the regulation mechanism of DDX20 on vitellogenin expression in Scylla paramamosain.

Vitellogenesis in crustaceans is controlled by several steroid hormones. In humans, the expression of SF-1, a gene that regulates gonadal development and the synthesis of steroid hormones, is affected by DDX20. However, how the homologous gene FTZ-F1 is regulated by DDX20 and its association with vitellogenesis remains unknown in the mud crab Scylla paramamosain. In this study, SpDDX20 and SpFTZ-F1 were identified in the transcriptome of mature ovarian tissue from the mud crab. qRT-PCR results revealed that the expression levels of SpFTZ-F1 and SpVTG in the ovaries of crab in the experimental group injected with dsDDX20 (EO) were significantly higher (P < 0.05) than those in the negative control group injected with dsEGFP (NO) and the blank control group injected with SPSS (BO). The differentially expressed genes (DEGs) identified by comparative transcriptome analysis of the EO group and NO group were enriched into five pathways related to ovarian steroidogenesis. The expression of CYP17, CYP3A4, CYP1A1 and 3ß-HSD were up-regulated in pathways related to steroid hormone production and biosynthesis. The expression of the INSR, IRS and PI3K genes in the insulin signaling pathway were significantly increased (P < 0.05). The expression level of the TGF-ß gene was up-regulated (P < 0.05) in the transforming growth factor pathway, whereas the expression level of the Smad2 gene was down-regulated (P < 0.05). The expression of GnRHR, GS, AC and PKA genes in the gonadotropin-releasing hormone signaling pathway were up-regulated. Our data provide a foundation for investigating the relationship between DDX20 and FTZ-F1 in the regulation of vitellogenin expression in S. paramamosain.

A Macrophage Differentiation-Mediated Gene: DDX20 as a Molecular Biomarker Encompassing the Tumor Microenvironment, Disease Staging, and Prognoses in Hepatocellular Carcinoma.

Background: DDX20 involves the mechanism of cell proliferate, mitogenic Ets transcriptional suppressor (METS), which can arrest the cell cycle of macrophages. However, little is known about DDX20 expression, clinical values, and the relationship with tumor microenvironment in HCC. Methods: We mined the transcriptional, protein expression and survival data of DDX20 in HCC from online databases. The immunological effects of DDX20 were estimated by bioinformatic algorithms. The RNAi and CRISPR screening were used to assess the gene effect of DDX20 for the EGFR gene in liver tumor cell. Results: We found that the DDX20 was highly expressed in HCC. The qRT-PCR result shows a significantly upregulated DDX20 expression in HCC samples from the West China Hospital. The high mRNA expression of DDX20 is associated with a poor survival. DDX20 expression is positively correlated with MDSCs in HCC tissues. Moreover, DDX20 has a high predicted ability for the response to immunotherapy. Furthermore, hsa-mir-324-5p could regulate the macrophage differentiation by interacting with DDX20. Meanwhile, the EGFR gene gets a high dependency score for DDX20. Conclusion: In sum, DDX20 may serve as a prognostic marker for worse clinical outcomes with HCC and potentially enable more precise and personalized immunotherapeutic strategies in the future.

Genetic Variation in DEAD-Box Helicase 20 as a Putative Marker of Recurrence in Propensity-Matched Colon Cancer Patients.

Variants of the DEAD-Box Helicase 20 (DDX20), one of the microRNAs (miRNAs) machinery genes, can modulate miRNA/target gene expressions and, hence, influence cancer susceptibility and prognosis. Here, we aimed to unravel the association of DDX20 rs197412 T/C variant with colon cancer risk and/or prognosis in paired samples of 122 colon cancer and non-cancer tissue specimens by TaqMan allelic discrimination analysis. Structural/functional bioinformatic analyses were carried out, followed by a meta-analysis. We found that the T allele was more frequent in cancer tissues compared to control tissues (60.2% vs. 35.7%, p < 0.001). Furthermore, the T variant was highly frequent in primary tumors with evidence of recurrence (73% vs. 47.5%, p < 0.001). Genetic association models, adjusted by age and sex, revealed that the T allele was associated with a higher risk of developing colon cancer under heterozygote (T/C vs. C/C: OR = 2.35, 95%CI = 1.25−4.44, p < 0.001), homozygote (T/T vs. C/C: OR = 7.6, 95%CI = 3.5−16.8, p < 0.001), dominant (T/C-T/T vs. C/C: OR = 3.4, 95%CI = 1.87−8.5, p < 0.001), and recessive (T/T vs. C/C-T/C: OR = 4.42, 95%CI = 2.29−8.54, p = 0.001) models. Kaplan−Meier survival curves showed the shift in the C > T allele to be associated with poor disease-free survival. After adjusting covariates using a multivariate cox regression model, patients harboring C > T somatic mutation were 3.5 times more likely to develop a recurrence (p < 0.001). A meta-analysis of nine studies (including ours) showed a higher risk of CRC (81%) in subjects harboring the T/T genotype than in T/C + C/C genotypes, supporting the potential clinical utility of the specified study variant as a biomarker for risk stratification in CRC cases. However, results were not significant in non-colorectal cancers. In conclusion, the DDX20 rs197412 variant is associated with increased colon cancer risk and a higher likelihood of recurrence in the study population.

The combined detection of Amphiregulin, Cyclin A1 and DDX20/Gemin3 expression predicts aggressive forms of oral squamous cell carcinoma.

BACKGROUND: Large-scale genetic and epigenetic deregulations enable cancer cells to ectopically activate tissue-specific expression programmes. A specifically designed strategy was applied to oral squamous cell carcinomas (OSCC) in order to detect ectopic gene activations and develop a prognostic stratification test. METHODS: A dedicated original prognosis biomarker discovery approach was implemented using genome-wide transcriptomic data of OSCC, including training and validation cohorts. Abnormal expressions of silent genes were systematically detected, correlated with survival probabilities and evaluated as predictive biomarkers. The resulting stratification test was confirmed in an independent cohort using immunohistochemistry. RESULTS: A specific gene expression signature, including a combination of three genes, AREG, CCNA1 and DDX20, was found associated with high-risk OSCC in univariate and multivariate analyses. It was translated into an immunohistochemistry-based test, which successfully stratified patients of our own independent cohort. DISCUSSION: The exploration of the whole gene expression profile characterising aggressive OSCC tumours highlights their enhanced proliferative and poorly differentiated intrinsic nature. Experimental targeting of CCNA1 in OSCC cells is associated with a shift of transcriptomic signature towards the less aggressive form of OSCC, suggesting that CCNA1 could be a good target for therapeutic approaches.

The multiple lives of DEAD-box RNA helicase DP103/DDX20/Gemin3.

Gemin3, also known as DDX20 or DP103, is a DEAD-box RNA helicase which is involved in more than one cellular process. Though RNA unwinding has been determined in vitro, it is surprisingly not required for all of its activities in cellular metabolism. Gemin3 is an essential gene, present in Amoeba and Metazoa. The highly conserved N-terminus hosts the helicase core, formed of the helicase- and DEAD-domains, which, based on crystal structure determination, have key roles in RNA binding. The C-terminus of Gemin3 is highly divergent between species and serves as the interaction site for several accessory factors that could recruit Gemin3 to its target substrates and/or modulate its function. This review article focuses on the known roles of Gemin3, first as a core member of the survival motor neuron (SMN) complex, in small nuclear ribonucleoprotein biogenesis. Although mechanistic details are lacking, a critical function for Gemin3 in this pathway is supported by numerous in vitro and in vivo studies. Gene expression activities of Gemin3 are next underscored, mainly messenger ribonucleoprotein trafficking, gene silencing via microRNA processing, and transcriptional regulation. The involvement of Gemin3 in abnormal cell signal transduction pathways involving p53 and NF-κB is also highlighted. Finally, the clinical implications of Gemin3 deregulation are discussed including links to spinal muscular atrophy, poliomyelitis, amyotrophic lateral sclerosis, and cancer. Impressive progress made over the past two decades since the discovery of Gemin3 bodes well for further work that refines the mechanism(s) underpinning its multiple activities.

Genetic variants of microRNA processing genes and risk of non-syndromic orofacial clefts.

OBJECTIVE: MicroRNA (miRNA) processing genes play important roles in the craniofacial development. The aim of this study was to explore the associations between single nucleotide polymorphisms (SNPs) of miRNA processing genes with the risk of non-syndromic orofacial clefts (NSOC). METHODS: We genotyped 12 potentially functional SNPs from seven miRNA processing genes (GEMIN3, DROSHA, DGCR8, GEMIN4, PIWIL1, XPO5, and DICER) in a case-control study of 602 NSOC cases and 605 controls. RESULTS: Two SNPs were associated with the susceptibility of CL/P: rs10719 in DROSHA led to an increased risk of cleft lip with or without palate (CL/P) (GA/AA: p = .024, OR = 1.33, 95% CI = [1.04, 1.70]; GG + GA/AA: p = .037, OR = 1.29, 95% CI = [1.02, 1.63]), while rs493760 in DROSHA (CC/TT: p = .049, OR = 0.58, 95% CI = [0.34, 0.99]) could reduce the risk of CL/P. In addition, rs10719 (A)-rs493760 (C) haplotype contributed to a decreased risk of CL/P (OR = 0.77, 95% CI = [0.63, 0.94]), whereas the rs10719 (G)-rs493760 (C) haplotype contributed to the increased risk of cleft palate only (CPO) (OR = 2.70, 95% CI = [1.15, 6.35]). However, there was no difference observed in these SNPs after the Bonferroni correction. CONCLUSION: Taken together, our results provided the potential evidence that rs10719 and rs493760 might contribute to the risk of CL/P and suggested potential genetic basis and mechanisms of CL/P. The lack of association between these SNPs and CPO might be due to the limited sample size of CPO subgroup.

Analysis of the polymorphic variants of RAN and GEMIN3 genes and risk of Primary Open-Angle Glaucoma in the Polish population.

BACKGROUND: Glaucoma is considered as a neurodegenerative disorder in which the optic nerve damage leads to irreversible blindness. Many scientific findings indicate miRNA implication in the neurodegeneration process. In this study, we aimed to evaluate the polymorphic variants of miRNA processing genes, RAN (rs14035) and GEMIN3 (rs197388), and their association with a risk of primary open-angle glaucoma (POAG) in relation to selected clinical parameters. MATERIALS AND METHODS: The study included 246 POAG patients and 188 controls. The selected gene polymorphisms were analyzed by TaqMan SNP Genotyping Assay using DNA extracted from blood samples. RESULTS: The obtained results indicated that the AA genotype of rs197388 as well as the A allele in the same gene may be associated with an elevated risk of POAG development (P = 0.021, P = 0.017 respectively). The correlation between the data and clinical parameters has shown that the A allele of rs197388 in relation to retinal nerve fiber layer(RNFL) could be responsible for an increased risk of glaucoma occurrence (P = 0.028), while the AT genotype could be associated with a decreased risk of POAG according to the mean deviation parameter (P = 0.023). CONCLUSION: Our data has shown that GEMIN3 gene (rs197388) polymorphisms might be associated with a risk of POAG development in the Polish population. This is the first report evaluating the polymorphic variants of miRNA processing genes, RAN and GEMIN3, with a changed risk of glaucoma.

Regulating the Regulators in Attention-Deficit/Hyperactivity Disorder: A Genetic Association Study of microRNA Biogenesis Pathways.

Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent complex psychiatric disorders in children as well as adults. ADHD impacts not only the affected individuals but also their families and social and professional networks. The clinical and diagnostic criteria for ADHD remain imprecise, in part, due to lack of robust biomarkers. ADHD comprises multiple subsets of diseases that present a shared set of downstream clinical findings, while displaying extensive molecular heterogeneity. This calls for innovation in diagnostic strategies that can help establish an ADHD diagnosis unequivocally as well as guiding precision medicine in this common mental health disorder. No study has examined, to the best of our knowledge, the upstream regulation of miRNAs that impact the downstream final ADHD phenotype. The latter focus on putative genetic biomarkers that regulate the regulators and can be tested empirically, for example, through genetic association analyses of the biogenesis pathways for miRNAs that impact the ADHD phenotype. Hence, we report here polymorphic variation in 10 miRNA biogenesis pathway candidate genes, including RNASEN, DGCR8, XPO5, RAN, DICER1, TARBP2, AGO1, AGO2, GEMIN3, and GEMIN4, in a large sample from the Eastern Mediterranean region (N = 355; 191 cases and 164 controls). We found that AGO1 rs595961 was significantly associated with ADHD susceptibility (p < 0.05). While polymorphic variation in other miRNA biogenesis pathway genes did not display a significant association in the present sample, the observations reported herein on miRNA biogenesis variation offer a new avenue of research for innovation in biomarker discovery concerning ADHD and other complex psychiatric diseases with major global health burden.

Genetic variants in RNA-induced silencing complex genes and prostate cancer.

PURPOSE: The purpose of this study is to evaluate the potential association between genetic variants in genes encoding the components of RNA-induced silencing complex and prostate cancer (PCa) risk. Genetic variants chosen for this study are rs3742330 in DICER1, rs4961280 in AGO2, rs784567 in TARBP2, rs7813 in GEMIN4 and rs197414 in GEMIN3. METHODS: The study involved 355 PCa patients, 360 patients with benign prostatic hyperplasia and 318 healthy controls. For individuals diagnosed with PCa, clinicopathological characteristics including serum prostate-specific antigen level at diagnosis, Gleason score (GS) and clinical stage were determined. Genotyping was performed using high-resolution melting analysis, PCR-RFLP, TaqMan SNP Genotyping Assay and real-time PCR-based genotyping assay using specific probes. Allelic and genotypic associations were evaluated by unconditional linear and logistic regression methods. RESULTS: The study provided no evidence of association between the analyzed genetic variants and PCa risk. Nevertheless, allele A of rs784567 was found to confer the reduced risk of higher serum PSA level at diagnosis (P = 0.046; Difference = -66.64, 95 % CI -131.93 to 1.35, for log-additive model). Furthermore, rs4961280, as well as rs3742330, were shown to be associated with GS. These variants, together with rs7813, were found to be associated with the lower clinical stage of PCa. Also, rs3742330 minor allele G was found to be associated with lower PCa aggressiveness (P = 0.036; OR 0.14, 95 % CI 0.023-1.22, for recessive model). CONCLUSIONS: According to our data, rs3742330, rs4961280 and rs7813 qualify for potentially protective genetic variants against PCa progression. These variants were not shown to be associated with PCa risk.

Significance of microRNA-related variants in susceptibility to recurrence of oropharyngeal cancer patients after definitive radiotherapy.

Common single nucleotide polymorphisms (SNPs) in miRNAs may affect miRNA functions and their target expression and thus may affect biological activities and cancer etiology as well as prognosis. Thus, we determined whether the 9 SNPs in microRNAs modify the risk of recurrence of squamous cell carcinoma of the oropharynx (SCCOP) in a cohort of 1008 patients. The log-rank test and multivariate Cox models were used to evaluate the associations. We found that the SNPs in the miRNA146, miRNA196, and Gemin3 were associated with a significantly reduced and increased risk of SCCOP recurrence after multivariate adjustment (aHR, 0.6, 95%CI, 0.4-0.9, aHR, 2.1, 95%CI, 1.6-2.8, and aHR, 0.6, 95%CI, 0.5-0.9, respectively). Furthermore, the similar effect of these 3 SNPs on SCCOP recurrence risk was found in HPV-positive SCCOP patients only. However, no significant associations were found for other SNPs. To evaluate the aggregate effects of these SNPs, we performed a combined risk genotype analysis. We found that, compared with the low-risk reference group with less than 4 risk genotypes, the medium-risk group with 4 or 5 risk genotypes exhibited a 1.7-fold (1.2-2.4) increased risk whereas the high-risk group with more than 5 risk genotypes exhibited a 3.0-fold (1.7-4.2) increased risk (Ptrend < 0.001). Such combined effects were particularly pronounced in HPV-positive SCCOP patients. Taken together, this is the first study with a large cohort of SCCOP patients showing that miRNA-related genetic variants may modify risk of SCCOP recurrence individually and jointly. Larger studies are needed to validate these results.

High expression of DDX20 enhances the proliferation and metastatic potential of prostate cancer cells through the NF-κB pathway.

DEAD (Asp-Glu-Ala-Asp) box polypeptide 20 (DDX20), a member of the DEAD box protein family, encodes an RNA helicase. Previous research has revealed that DDX20 may act as a tumor suppressor in hepatocellular carcinoma and as a tumor promoter in breast cancer. These conflicting reports prompted us to explore the role of DDX20 in prostate cancer (PCa). To gain insight into the functions of DDX20 in PCa, we examined DDX20 expression patterns in a PCa tissue microarray with 99 PCa tissue samples. The results of immunohistochemical staining revealed that DDX20 expression is frequently upregulated in PCa tissues compared with that in the adjacent tissues and further clinicopathological analysis showed that the expression level of DDX20 closely correlates with tumor size, TNM stage (positive correlation) and patient prognosis (negative correlation). Both gain­of- and loss­of­function assays were performed in vitro; the overexpression of DDX20 enhanced the proliferation and metastatic potential of cancer cells and this was examined by performing a cell counting kit-8 (CCK-8) assay, wound healing assay and Transwell migration assay. Furthermore, we found that there is a positive correlation between the expression of matrix metallopeptidase 9 (MMP9) and DDX20 expression. These findings led us to examine whether DDX20 may exert effects through the NF­κB pathway. Luciferase reporter assays suggested that DDX20 altered the activity of NF-κB. Taken together, these findings show that DDX20 may promote the progression of PCa through the NF-κB pathway.

FOXL2 down-regulates vitellogenin expression at mature stage in Eriocheir sinensis.

Ovarian development in crustaceans is characterized by rapid production of egg yolk protein in a process called vitellogenesis. In the present study, we investigated the involvement of a DEAD (Asp-Glu-Ala-Asp) box RNA helicase 20 (DDX20), forkhead transcription factor (FOXL)2 and fushi tarazu factor (FTZ-F)1 in the regulation of vitellogenesis. Based on ESTs from the testis and accessory gland of Eriocheir sinensis, we cloned the full-length cDNAs of foxl2 and fushitarazu factor 1 (ftz-f1), which include the conserved structural features of the forkhead family and nuclear receptor 5A (NR5A) family respectively. The expression of foxl2 mRNA surged at the mature stage of the ovary, when vtg mRNA swooped, suggesting that foxl2 negatively affects the vitellogenin (VTG) synthesis at this developmental stage. Etoposide (inducing germ cell apoptosis) treatment up-regulated FOXL2 and DDX20 at both the mRNA and the protein levels, primarily in the follicular cells as shown by immunofluorescence analysis. Furthermore, foxl2, ddx20 and ftz-f1 mRNA levels increased significantly with right-eyestalk ablation. Interactions between FOXL2 and DDX20 or FTZ-F1 were confirmed by co-immunoprecipitation and the forkhead domain of FOXL2 was identified as the specific structure interacting with FTZ-F1. In conclusion, FOXL2 down-regulates VTG expression by binding with DDX20 in regulation of follicular cell apoptosis and with FTZ-F1 to repress the synthesis of VTG at the mature stage. This report is the first to describe the molecular mechanism of VTG synthesis in E. sinensis and may shed new light on the regulation of cytochrome P450 enzyme by FOXL2 and FTZ-F1 in vitellogenesis.

Intracellular Bacterial Pathogens Trigger the Formation of U Small Nuclear RNA Bodies (U Bodies) through Metabolic Stress Induction.

Invasive bacterial pathogens induce an amino acid starvation (AAS) response in infected host cells that controls host defense in part by promoting autophagy. However, whether AAS has additional significant effects on the host response to intracellular bacteria remains poorly characterized. Here we showed that Shigella, Salmonella, and Listeria interfere with spliceosomal U snRNA maturation in the cytosol. Bacterial infection resulted in the rerouting of U snRNAs and their cytoplasmic escort, the survival motor neuron (SMN) complex, to processing bodies, thus forming U snRNA bodies (U bodies). This process likely contributes to the decline in the cytosolic levels of U snRNAs and of the SMN complex proteins SMN and DDX20 that we observed in infected cells. U body formation was triggered by membrane damage in infected cells and was associated with the induction of metabolic stresses, such as AAS or endoplasmic reticulum stress. Mechanistically, targeting of U snRNAs to U bodies was regulated by translation initiation inhibition and the ATF4/ATF3 pathway, and U bodies rapidly disappeared upon removal of the stress, suggesting that their accumulation represented an adaptive response to metabolic stress. Importantly, this process likely contributed to shape the host response to invasive bacteria because down-regulation of DDX20 expression using short hairpin RNA (shRNA) amplified ATF3- and NF-κB-dependent signaling. Together, these results identify a critical role for metabolic stress and invasive bacterial pathogens in U body formation and suggest that this process contributes to host defense.

Reconstitution of the human U snRNP assembly machinery reveals stepwise Sm protein organization.

The assembly of spliceosomal U snRNPs depends on the coordinated action of PRMT5 and SMN complexes in vivo. These trans-acting factors enable the faithful delivery of seven Sm proteins onto snRNA and the formation of the common core of snRNPs. To gain mechanistic insight into their mode of action, we reconstituted the assembly machinery from recombinant sources. We uncover a stepwise and ordered formation of distinct Sm protein complexes on the PRMT5 complex, which is facilitated by the assembly chaperone pICln. Upon completion, the formed pICln-Sm units are displaced by new pICln-Sm protein substrates and transferred onto the SMN complex. The latter acts as a Brownian machine that couples spontaneous conformational changes driven by thermal energy to prevent mis-assembly and to ensure the transfer of Sm proteins to cognate RNA. Investigation of mutant SMN complexes provided insight into the contribution of individual proteins to these activities. The biochemical reconstitution presented here provides a basis for a detailed molecular dissection of the U snRNP assembly reaction.

A Survival Association Study of 102 Polymorphisms Previously Associated with Survival Outcomes in Colorectal Cancer.

Several published studies identified associations of a number of polymorphisms with a variety of survival outcomes in colorectal cancer. In this study, we aimed to explore 102 previously reported common genetic polymorphisms and their associations with overall survival (OS) and disease-free survival (DFS) in a colorectal cancer patient cohort from Newfoundland (n = 505). Genotypes were obtained using a genomewide SNP genotyping platform. For each polymorphism, the best possible genetic model was estimated for both overall survival and disease-free survival using a previously published approach. These SNPs were then analyzed under their genetic models by Cox regression method. Correction for multiple comparisons was performed by the False Discovery Rate (FDR) method. Univariate analysis results showed that RRM1-rs12806698, IFNGR1-rs1327474, DDX20-rs197412, and PTGS2-rs5275 polymorphisms were nominally associated with OS or DFS (p < 0.01). In stage-adjusted analysis, the nominal associations of DDX20-rs197412, PTGS2-rs5275, and HSPA5-rs391957 with DFS were detected. However, after FDR correction none of these polymorphisms remained significantly associated with the survival outcomes. We conclude that polymorphisms investigated in this study are not associated with OS or DFS in our colorectal cancer patient cohort.

Association of microRNA biogenesis pathway gene variants and alcohol dependence risk.

Alcohol dependence (AD) is a neuropsychiatric disorder to which both genetic and environmental factors contribute. Especially, multiple genetic factors are promising to explain the etiology of AD. microRNAs (miRNAs) are members of a family of noncoding small RNAs, which are thought to be responsible for the altered gene expression in neuropsychiatric disorders. We hypothesized that single nucleotide polymorphisms (SNPs) in the miRNA biogenesis pathway may result in dysregulation of miRNA levels inside the cell. The aim of this study was to test an association between miRNA biogenesis gene variants and AD risk. Real-time polymerase chain reaction genotyping experiment was conducted on DNA samples from 123 alcohol-dependent patients and 135 healthy controls. We found that AGO1 rs595961 (χ(2) = 9.066, p = 0.003; odds ratio [OR] = 0.459, 95% confidence interval [CI]: 0.275-0.768) and AGO2 rs4961280 (χ(2) = 4.111, p = 0.043; OR = 0.590, 95% CI: 0.353-0.986) G alleles have significantly altered the risk for AD, and also there is a significant association of GEMIN4 rs910924 (χ(2) = 5.291, p = 0.021; OR = 1.913, 95% CI: 1.094-3.344) T allele with the risk for AD. We also found statistically significant difference in AGO1 rs595961 (χ(2) = 11.139, p = 0.001) and DGCR8 rs1640299 (χ(2) = 13.001, p = 0.002) genotype frequencies between case-control groups. This is the first study to investigate the effects of SNPs in the miRNA biogenesis pathway on AD risk. In conclusion, we identified a significant association of miRNA biogenesis genes with altered AD risk, and these results could be a guide to research on the role of miRNAs in AD in the future.

DEAD-box helicase DP103 defines metastatic potential of human breast cancers.

Despite advancement in breast cancer treatment, 30% of patients with early breast cancers experience relapse with distant metastasis. It is a challenge to identify patients at risk for relapse; therefore, the identification of markers and therapeutic targets for metastatic breast cancers is imperative. Here, we identified DP103 as a biomarker and metastasis-driving oncogene in human breast cancers and determined that DP103 elevates matrix metallopeptidase 9 (MMP9) levels, which are associated with metastasis and invasion through activation of NF-κB. In turn, NF-κB signaling positively activated DP103 expression. Furthermore, DP103 enhanced TGF-ß-activated kinase-1 (TAK1) phosphorylation of NF-κB-activating IκB kinase 2 (IKK2), leading to increased NF-κB activity. Reduction of DP103 expression in invasive breast cancer cells reduced phosphorylation of IKK2, abrogated NF-κB-mediated MMP9 expression, and impeded metastasis in a murine xenograft model. In breast cancer patient tissues, elevated levels of DP103 correlated with enhanced MMP9, reduced overall survival, and reduced survival after relapse. Together, these data indicate that a positive DP103/NF-κB feedback loop promotes constitutive NF-κB activation in invasive breast cancers and activation of this pathway is linked to cancer progression and the acquisition of chemotherapy resistance. Furthermore, our results suggest that DP103 has potential as a therapeutic target for breast cancer treatment.

A miRNA machinery component DDX20 controls NF-κB via microRNA-140 function.

Hepatocellular carcinoma is the third leading cause of cancer mortality worldwide, but the molecular mechanisms in tumorigenesis remain largely unknown. Previously, a DEAD-box protein DDX20, a component of microRNA-containing ribonucleoprotein complexes, was identified as a liver tumor suppressor candidate in an oncogenomics-based in vivo RNAi screen. However, the molecular mechanisms were unknown. Here, we show that deficiency of DDX20 results in the enhancement of NF-κB activity, a crucial intracellular signaling pathway closely linked with hepatocarcinogenesis. While DDX20 normally suppresses NF-κB activity by regulating NF-κB-suppressing miRNA-140 function, this suppressive effect was lost in DDX20-deficient cells. The impairment of miRNA function due to DDX20 deficiency appears to be miRNA species-specific at the point of loading miRNAs into the RNA-induced silencing complex. These results indicate that DDX20 deficiency enhances NF-κB activity by impairing the NF-κB-suppressive action of microRNAs, and suggest that dysregulation of the microRNA machinery components may also be involved in pathogenesis in various human diseases.

Epstein-Barr virus nuclear antigen 3C stabilizes Gemin3 to block p53-mediated apoptosis.

The Epstein-Barr nuclear antigen 3C (EBNA3C), one of the essential latent antigens for Epstein-Barr virus (EBV)-induced immortalization of primary human B lymphocytes in vitro, has been implicated in regulating cell proliferation and anti-apoptosis via interaction with several cellular and viral factors. Gemin3 (also named DDX20 or DP103) is a member of DEAD RNA helicase family which exhibits diverse cellular functions including DNA transcription, recombination and repair, and RNA metabolism. Gemin3 was initially identified as a binding partner to EBNA2 and EBNA3C. However, the mechanism by which EBNA3C regulates Gemin3 function remains unclear. Here, we report that EBNA3C directly interacts with Gemin3 through its C-terminal domains. This interaction results in increased stability of Gemin3 and its accumulation in both B lymphoma cells and EBV transformed lymphoblastoid cell lines (LCLs). Moreover, EBNA3C promotes formation of a complex with p53 and Gemin3 which blocks the DNA-binding affinity of p53. Small hairpin RNA based knockdown of Gemin3 in B lymphoma or LCL cells remarkably attenuates the ability of EBNA3C to inhibit the transcription activity of p53 on its downstream genes p21 and Bax, as well as apoptosis. These findings provide the first evidence that Gemin3 may be a common target of oncogenic viruses for driving cell proliferation and anti-apoptotic activities.

[Gemin3 inhibits cell apoptosis through suppression of p53 expression].

OBJECTIVE: To investigate the role of Gemin3 in cell proliferation and its regulation pathway. METHODS: Using co-immunoprecipitation and GST pull-down assay to determine the domain of Gemin3 and p53 binding and interaction in vitro and in vivo. To check the effect of Gemin3 on p53 by luciferase reporter assay. Stable Gemin3 knock-down cell lines were generated by lentivirus-delivered small hairpin RNA then puromycin selection. Real-time PCR was used to confirm the effect of Gemin3 level on p53 and its downstream genes, and flow cytometry was used to analyze the effect of Gemin3 on apoptosis. RESULTS: The C-terminal of Gemin3 interacted with the DNA binding domain of p53. The p53 reporter gene, PA3M-p53 and increasing amount of GFP-Gemin3 were co-transfected into Saos-2 cells. Gemin3 repressed p53 expression at transcription level. Real-time PCR indicated that the expression of p53, p21 and Bax in Gemin3 knock-down cells was higher than that in the control cells. Western blot showed Gemin3 knock-down cells had a higher p53 espression. Flow cytometric assay showed that knock-down Gemin3 expression led to an increased cell apoptosis. CONCLUSION: Gemin3 binds with p53 forming a complex and plays an anti-apoptotic role by repressing the p53 expression.