DDX5 promotes proliferation and tumorigenesis of non-small-cell lung cancer cells by activating β-catenin signaling pathway

The RNA-binding protein CMSS1 promotes the progression of non-small cell lung cancer by regulating the telomerase protein subunit hTERT

AIMS

High telomerase activity has been detected in over 85 % of tumors, with the activation of hTERT being the most crucial mechanism for re-establishing telomerase activity. Activation of hTERT maintains telomere length in cells, enabling cancer cells to proliferate indefinitely. Nevertheless, the specific mechanism of telomerase activation in non-small cell lung cancer (NSCLC) remains unclear, and post-transcriptional regulation of hTERT could be a potential activation mechanism.

MATERIALS AND METHODS

We explored the regulatory impact of CMSS1 on hTERT expression in NSCLC cells using several methods: Yeast three-hybrid system, Reporter gene assay, Western blot, RNA decay assay, and Telomere length measurement. Our analysis revealed significant overexpression of CMSS1 in NSCLC, which correlated with poor prognosis, as determined by bioinformatics and tissue microarray techniques. RNA sequencing analysis showed that CMSS1 knockdown influenced the adhesion capabilities of NSCLC cells. Additionally, potential interacting proteins with CMSS1 were identified through mass spectrometry and co-immunoprecipitation experiments.

KEY FINDINGS

We discovered that CMSS1 regulates hTERT expression in NSCLC cells by binding to the 5' UTR of hTERT mRNA, impacting its mRNA stability and thereby influencing NSCLC progression. RNA-Seq results and adhesion experiments indicated that CMSS1 knockdown disrupts cell adhesion. hTERT also affects cell adhesion in NSCLC, underscoring CMSS1's role as an upstream regulator of hTERT. Mass spectrometry and Co-IP studies suggest potential interactions between CMSS1, RBM34, and DDX5 that further modulate hTERT expression.

SIGNIFICANCE

These findings indicate that CMSS1 plays a crucial role in NSCLC progression through its interaction with hTERT, making it a promising therapeutic target.

LncRNA GATA3-AS1 Promotes Bladder Uroepithelial Cancer Progression by Stabilizing DDX5

Objective: Exploration of molecular markers is an ongoing focus in the field of bladder cancer research. Based on data from public databases, GATA3-AS1 was identified as upregulated in bladder urothelial carcinoma (BLCA); however, its exact function and regulatory mechanism in this context remain unclear. Methods: To investigate the clinical implications of GATA3-AS1, we examined its levels in 90 BLCA and adjoining normal tissue samples. Functional assays were conducted to assess the effects of GATA3-AS1 on BLCA cell proliferation, migration, and invasion. Animal assays were employed to determine the effects of GATA3-AS1 on BLCA tumorigenicity in vivo. Immunoblotting, RNA pull-down, RNA immunoprecipitation, TOP/FOP luciferase reporter gene, and coimmunoprecipitation assays were used to explore the molecular mechanism underlying the effects of GATA3-AS1 on BLCA progression. Results: GATA3-AS1 expression was significantly up-regulated in BLCA tissues and correlated with pathological stage, grade, and poor patient outcome. Altered GATA3-AS1 levels promoted BLCA proliferation, migration, and invasion. Mechanistic studies suggested that GATA3-AS1 interacts with DDX5 protein, enhances its stability, and ultimately leads to BLCA progression through Wnt/β-catenin signaling pathway activation. Conclusion: GATA3-AS1 overexpression increases the aggressiveness of BLCA by activating the Wnt/β-catenin pathway through binding to DDX5. GATA3-AS1 has potential as a new molecular predictor of poor prognosis in patients with BLCA.

Established and Emerging Roles of DEAD/H-Box Helicases in Regulating Infection and Immunity

The sensing of nucleic acids by DEAD/H-box helicases, specifically retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated protein 5 (MDA5), plays a critical role in inducing antiviral immunity following infection. However, this DEAD/H-box helicase family includes many additional proteins whose immune functions have not been investigated. While numerous DEAD/H-box helicases contribute to antiviral immunity, they employ diverse mechanisms beyond the direct sensing of nucleic acids. Some members have also been identified to play proviral (promoting virus replication/propagation) roles during infections, regulate other non-viral infections, and contribute to the regulation of autoimmunity and cancer. This review synthesizes the known and emerging functions of the broader DEAD/H-box helicase family in immune regulation and highlights ongoing efforts to target these proteins therapeutically.

DEAD-box helicase family proteins: emerging targets in digestive system cancers and advances in targeted drug development

Cancer has become one of the major diseases threatening human health in the twenty-first century due to its incurability. In 2022, new cases of esophageal and gastrointestinal cancers accounted for 17.1% of all newly diagnosed cancer cases worldwide. Despite significant improvements in early cancer screening, clinical diagnostics, and treatments in recent years, the overall prognosis of digestive system cancer patients remains poor. The DEAD-box helicase family, a crucial member of the RNA helicase family, participates in almost every aspect of RNA metabolism, including transcription, splicing, translation, and degradation, and plays a key role in the occurrence and progression of various cancers. This article aims to summarize and discuss the role and potential clinical applications of DEAD-box helicase family proteins in digestive system cancers. The discussion includes the latest progress in the occurrence, development, and treatment of esophageal and gastrointestinal tumors; the main functions of DEAD-box helicase family proteins; their roles in digestive system cancers, including their relationships with clinical factors; effects on cancer proliferation, migration, and invasion; and involved signaling pathways; as well as the existing inhibitory strategies targeting DDX family proteins, are discussed. Additionally, outlooks on future research directions are provided.

DEAD/H Box 5 (DDX5) Augments E2F1-Induced Cell Death Independent of the Tumor Suppressor p53

In almost all cancers, the p53 pathway is disabled and cancer cells survive. Hence, it is crucially important to induce cell death independent of p53 in the treatment of cancers. The transcription factor E2F1 is controlled by binding of the tumor suppressor pRB, and induces apoptosis by activating the ARF gene, an upstream activator of p53, when deregulated from pRB by loss of pRB function. Deregulated E2F1 can also induce apoptosis, independent of p53, via other targets such as TAp73 and BIM. We searched for novel E2F1-interacting proteins and identified the RNA helicase DEAD/H box 5 (DDX5), which also functions as a transcriptional coactivator. In contrast to the reported growth-promoting roles of DDX5, we show that DDX5 suppresses cell growth and survival by augmentation of deregulated E2F1 activity. Over-expression of DDX5 enhanced E2F1 induction of tumor suppressor gene expression and cell death. Conversely, shRNA-mediated knockdown of DDX5 compromised both. Moreover, DDX5 modulated E2F1-mediated cell death independent of p53, for which DDX5 also functions as a coactivator. Since p53 function is disabled in almost all cancers, these results underscore the roles of DDX5 in E2F1-mediated induction of cell death, independent of p53, and represent novel aspects for the treatment of p53-disabled cancer cells.

On the interface of aging, cancer, and neurodegeneration with SIRT6 and L1 retrotransposon protein interaction network

Roles of the sirtuins in aging and longevity appear related to their evolutionarily conserved functions as retroviral-restriction factors. Retrotransposons also promote the aging process, which can be reversed by the inhibition of their activity. SIRT6 can functionally limit the mutation activity of LINE-1 (L1), a retrotransposon causing cancerogenesis-linked mutations accumulating during aging. Here, an overview of the molecular mechanisms of the controlling effects was created by the pathway enrichment and gene function prediction analysis of a protein interaction network of SIRT6 and L1 retrotransposon proteins L1 ORF1p, and L1 ORF2p. The L1-SIRT6 interaction network is enriched in pathways and nodes associated with RNA quality control, DNA damage response, tumor-related and retrotransposon activity-suppressing functions. The analysis also highlighted sumoylation, which controls protein-protein interactions, subcellular localization, and other post-translational modifications; DNA IR Damage and Cellular Response via ATR, and Hallmark Myc Targets V1, which scores are a measure of tumor aggressiveness. The protein node prioritization analysis emphasized the functions of tumor suppressors p53, PARP1, BRCA1, and BRCA2 having L1 retrotransposon limiting activity; tumor promoters EIF4A3, HNRNPA1, HNRNPH1, DDX5; and antiviral innate immunity regulators DDX39A and DDX23. The outline of the regulatory mechanisms involved in L1 retrotransposition with a focus on the prioritized nodes is here demonstrated in detail. Furthermore, a model establishing functional links between HIV infection, L1 retrotransposition, SIRT6, and cancer development is also presented. Finally, L1-SIRT6 subnetwork SIRT6-PARP1-BRCA1/BRCA2-TRIM28-PIN1-p53 was constructed, where all nodes possess L1 retrotransposon activity-limiting activity and together represent candidates for multitarget control.

METTL1-modulated LSM14A facilitates proliferation and migration in glioblastoma via the stabilization of DDX5

Glioblastoma (GBM) is characterized by aggressive growth, invasiveness, and poor prognosis. Elucidating the molecular mechanisms underlying GBM is crucial. This study explores the role of Sm-like protein 14 homolog A (LSM14A) in GBM. Bioinformatics and clinical tissue samples analysis demonstrated that overexpression of LSM14A in GBM correlates with poorer prognosis. CCK8, EdU, colony formation, and transwell assays revealed that LSM14A promotes proliferation, migration, and invasion in GBM in vitro. In vivo mouse xenograft models confirmed the results of the in vitro experiments. The mechanism of LSM14A modulating GBM cell proliferation was investigated using mass spectrometry, co-immunoprecipitation (coIP), protein half-life, and methylated RNA immunoprecipitation (MeRIP) analyses. The findings indicate that during the G1/S phase, LSM14A stabilizes DDX5 in the cytoplasm, regulating CDK4 and P21 levels. Furthermore, METTL1 modulates LSM14A expression via mRNA m7G methylation. Altogether, our work highlights the METTL1-LSM14A-DDX5 pathway as a potential therapeutic target in GBM.

Ddx5 Targeted Epigenetic Modification of Pericytes in Pulmonary Hypertension After Intrauterine Growth Restriction

Newborns with intrauterine growth restriction (IUGR) have a higher likelihood of developing pulmonary arterial hypertension (PAH) in adulthood. Although there is increasing evidence suggesting that pericytes play a role in regulating myofibroblast transdifferentiation and angiogenesis in malignant and cardiovascular diseases, their involvement in the pathogenesis of IUGR-related pulmonary hypertension and the underlying mechanisms remain incompletely understood. To address this issue, a study was conducted using a Sprague-Dawley rat model of IUGR-related pulmonary hypertension. Our investigation revealed increased proliferation and migration of pulmonary microvascular pericytes in IUGR-related pulmonary hypertension, accompanied by weakened endothelial-pericyte interactions. Through whole-transcriptome sequencing, Ddx5 (DEAD-box protein 5) was identified as one of the hub genes in pericytes. DDX5, a member of the RNA helicase family, plays a role in the regulation of ATP-dependent RNA helicase activities and cellular function. MicroRNAs have been implicated in the pathogenesis of PAH, and microRNA-205 (miR-205) regulates cell proliferation, migration, and angiogenesis. The results of dual-luciferase reporter assays confirmed the specific binding of miR-205 to Ddx5. Mechanistically, miR-205 negatively regulates Ddx5, leading to the degradation of β-catenin by inhibiting the phosphorylation of Gsk3β at serine 9. In vitro experiments showed the addition of miR-205 effectively ameliorated pericyte dysfunction. Furthermore, in vivo experiments demonstrated that miR-205 agomir could ameliorate pulmonary hypertension. Our findings indicated that the downregulation of miR-205 expression mediates pericyte dysfunction through the activation of Ddx5. Therefore, targeting the miR-205/Ddx5/p-Gsk3β/β-catenin axis could be a promising therapeutic approach for IUGR-related pulmonary hypertension.

RNA helicase DDX5-induced circPHF14 promotes gastric cancer cell progression

As a well-established member of a strongly conserved protein family, DDX5 binds to RNA helicase in a specific manner, which can regulate mRNA transcription, protein translation and synthesis and precursor messenger RNA processing or alternative splicing. The effects of DDX5 on carcinogenesis and cancer progression are increasingly evident. Circular RNAs (circRNAs), a novel group of functionally non-coding RNAs (ncRNAs) with disordered expression, are associated with various pathological processes (e.g., tumors). circRNA pattern and its function regulated by DDX5 have not yet been determined. According to our findings, DDX5 was dramatically upregulated for stomach cancer tissues, and its overexpression contributed to the cell growth and invasion of GC cells. Based on the analysis of genome-wide circRNAs conducted with circRNA sequencing, DDX5 induces a large number of circRNAs. Further to screen several circRNAs from PHF14 for function, it was found that circPHF14 was essential for the growth and tumorigenesis of DDX5-positive gastric cancer cells. These findings suggest that in addition to the messenger RNA and microRNA patterns, DDX5 also effects a circRNA pattern, as demonstrated by circPHF14. DDX5-induced circRNAs have been found to be of crucial importance for the growth of DDX5-positive gastric cancer cells, providing a new therapeutic target.

MSC-derived extracellular vesicles as nanotherapeutics for promoting aged liver regeneration

Aging is one of the critical factors to impair liver regeneration leading to a high incidence of severe complications after hepatic surgery in the elderly population without any effective treatment for clinical administration. As cell-free nanotherapeutics, mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been demonstrated the therapeutic potentials on liver diseases. However, the effects of MSC-EVs on the proliferation of aged hepatocytes are largely unclear. In this study, we found MSCs could reduce the expression of senescence-associated markers in the liver and stimulate its regeneration in aged mice after receiving a two-thirds partial hepatectomy (PHx) through their secreted MSC-EVs. Using RNA-Seq and AAV9 vector, we mechanistically found that these effects of UC-MSC-EVs partially attributed to inducing Atg4B-related mitophagy. This effect repairs the mitochondrial status and functions of aged hepatocytes to promote their proliferation. And protein mass spectrum analysis uncovered that DEAD-Box Helicase 5 (DDX5) enriches in UC-MSC-EVs, which interacts with E2F1 to facilitate its nuclear translocation for activating the expression of Atg4B. Collectively, our data show that MSC-EVs act nanotherapeutic potentials in anti-senescence and promoting regeneration of aged liver by transferring DDX5 to regulate E2F1-Atg4B signaling pathway that induce mitophagy, which highlights the clinical application valuation of MSC-EVs for preventing severe complications in aged population receiving liver surgery.

Nonstructural N- and C-tails of Dbp2 confer the protein full helicase activities

Human DDX5 and its yeast ortholog Dbp2 are ATP-dependent RNA helicases that play a key role in normal cell processes, cancer development and viral infection. The crystal structure of the RecA1-like domain of DDX5 is available, but the global structure of DDX5/Dbp2 subfamily proteins remains to be elucidated. Here, we report the first X-ray crystal structures of the Dbp2 helicase core alone and in complex with adenosine diphosphate nucleotide (ADP) at 3.22 Å and 3.05 Å resolutions, respectively. The structures of the ADP-bound post-hydrolysis state and apo-state demonstrate the conformational changes that occur when the nucleotides are released. Our results showed that the helicase core of Dbp2 shifted between open and closed conformation in solution, but the unwinding activity was hindered when the helicase core was restricted to a single conformation. A small-angle X-ray scattering (SAXS) experiment showed that the disordered amino- (N-) and carboxy- (C-) tails are flexible in solution. Truncation mutations confirmed that the N- and C-tails were critical for the nucleic acid binding, ATPase, and unwinding activities, with the C-tail being exclusively responsible for the annealing activity. Furthermore, we labeled the terminal tails to observe the conformational changes between the disordered tails and the helicase core upon binding nucleic acid substrates. Specifically, we found that the nonstructural N- and C-tails bind to RNA substrates and tether them to the helicase core domain, thereby conferring full helicase activities to the Dbp2 protein. This distinct structural characteristic provides new insight into the mechanism of DEAD-box RNA helicases.

RNA binding protein DDX5 restricts RORγt+ Treg suppressor function to promote intestine inflammation

Retinoid-related orphan receptor (RAR) gamma (RORγt)-expressing regulatory T cells (RORγt+ Tregs) play pivotal roles in preventing T cell hyperactivation and maintaining tissue homeostasis, in part by secreting the anti-inflammation cytokine interleukin-10 (IL-10). Here, we report that hypoxia-induced factor 1α (HIF1α) is the master transcription factor for Il10 in RORγt+ Tregs. This critical anti-inflammatory pathway is negatively regulated by an RNA binding protein DEAD box helicase 5 (DDX5). As a transcriptional corepressor, DDX5 restricts the expression of HIF1α and its downstream target gene Il10 in RORγt+ Tregs. T cell-specific Ddx5 knockout (DDX5ΔT) mice have augmented RORγt+ Treg suppressor activities and are better protected from intestinal inflammation. Genetic ablation or pharmacologic inhibition of HIF1α restores enteropathy susceptibility in DDX5ΔT mice. The DDX5-HIF1α-IL-10 pathway is conserved in mice and humans. These findings reveal potential therapeutic targets for intestinal inflammatory diseases.

CSN6 Mediates Nucleotide Metabolism to Promote Tumor Development and Chemoresistance in Colorectal Cancer

Metabolic reprogramming can contribute to colorectal cancer progression and therapy resistance. Identification of key regulators of colorectal cancer metabolism could provide new approaches to improve treatment and reduce recurrence. Here, we demonstrate a critical role for the COP9 signalosome subunit CSN6 in rewiring nucleotide metabolism in colorectal cancer. Transcriptomic analysis of colorectal cancer patient samples revealed a correlation between CSN6 expression and purine and pyrimidine metabolism. A colitis-associated colorectal cancer model established that Csn6 intestinal conditional deletion decreased tumor development and altered nucleotide metabolism. CSN6 knockdown increased the chemosensitivity of colorectal cancer cells in vitro and in vivo, which could be partially reversed with nucleoside supplementation. Isotope metabolite tracing showed that CSN6 loss reduced de novo nucleotide synthesis. Mechanistically, CSN6 upregulated purine and pyrimidine biosynthesis by increasing expression of PHGDH, a key enzyme in the serine synthesis pathway. CSN6 inhibited β-Trcp-mediated DDX5 polyubiquitination and degradation, which in turn promoted DDX5-mediated PHGDH mRNA stabilization, leading to metabolic reprogramming and colorectal cancer progression. Butyrate treatment decreased CSN6 expression and improved chemotherapy efficacy. These findings unravel the oncogenic role of CSN6 in regulating nucleotide metabolism and chemosensitivity in colorectal cancer.

SIGNIFICANCE

CSN6 deficiency inhibits colorectal cancer development and chemoresistance by downregulating PHGDH to block nucleotide biosynthesis, providing potential therapeutic targets to improve colorectal cancer treatment.

PARP1 controls the transcription of CD24 by ADP-ribosylating the RNA helicase DDX5 in pancreatic cancer

The PARP1 protein plays a key role in DNA damage repair and ADP-ribosylation to regulate gene expression. Strategies to target PARP1 have rapidly been developed for cancer treatment. However, the role of the innate immune response in targeted anti-PARP1 therapy remains poorly understood. In this work, we aimed to elucidate the regulatory mechanism underlying the immunogenicity of PARP1 and explore efficient therapeutic strategies to enhance the antitumor effect of PARP inhibitors. The relationships between PARP1 expression and immunosuppressive factors were examined by qRTPCR and immunoblot analysis. DNA pull-down, chromatin immunoprecipitation-quantitative PCR (ChIPqPCR) and luciferase reporter assays were employed to reveal the mechanism by which the expression of the immune checkpoint regulator CD24 is regulated by PARP1. Phagocytosis assays and pancreatic cancer animal models were applied to evaluate the therapeutic effect of simultaneous disruption of PARP1 and the antiphagocytic factor CD24. Upregulation of the innate immunosuppressive factor CD24 was observed in pancreatic cancer during PARP1 inhibition. The activating effect of targeting CD24 on macrophage phagocytosis was verified. Then, we showed that PARP1 attenuated the transcription of CD24 by ADP-ribosylating the transcription factor DDX5 in pancreatic cancer. Combined blockade of PARP1 and the antiphagocytic factor CD24 elicited a synergetic antitumor effect in pancreatic cancer. Our research provided evidence that combination treatment with PARP inhibitors and CD24 blocking monoclonal antibodies (mAbs) could be an effective strategy to improve the clinical therapeutic response in pancreatic cancer.

The indispensable role of the RNA helicase DDX5 in tumorigenesis induced by the myeloproliferative neoplasm-associated JAK2V617F mutant

A point mutation (V617F) in the Janus kinase 2 (JAK2) gene results in the production of disorderly activated tyrosine kinase, which causes myeloproliferative neoplasms (MPN). We herein demonstrated that the RNA helicase DDX5 was highly expressed at the mRNA and protein levels through the activation of signal transducer and activator of transcription 5 (STAT5) in Ba/F3 cells expressing a JAK2V617F mutant and erythropoietin receptor (V617F/EpoR cells) and MPN patient-derived HEL cells. A treatment with the JAK1/2 inhibitor, ruxolitinib and STAT5 inhibitor, pimozide significantly inhibited DDX5 mRNA expression and enhanced the degradation of DDX5 in these cells, suggesting that the JAK2V617F mutant positively regulates DDX5 mRNA expression and DDX5 protein stability by activating STAT5. The knockdown of DDX5 specifically inhibited the activation of mechanistic target of rapamycin (mTOR) in V617F/EpoR cells and HEL cells and significantly suppressed the proliferation of these cells. Furthermore, the knockdown of DDX5 markedly suppressed tumorigenesis, splenomegaly, and liver hypertrophy caused by an inoculation of V617F/EpoR cells in nude mice. Collectively, these results revealed that JAK2V617F exhibits transforming activity by inducing the expression of DDX5 in a STAT5-dependent manner, indicating the potential of the JAK2V617F/STAT5/DDX5 axis as a therapeutic target in the treatment of MPN.

DDX5 mRNA-targeting antisense oligonucleotide as a new promising therapeutic in combating castration-resistant prostate cancer

The heat shock protein 27 (Hsp27) has emerged as a principal factor of the castration-resistant prostate cancer (CRPC) progression. Also, an antisense oligonucleotide (ASO) against Hsp27 (OGX-427 or apatorsen) has been assessed in different clinical trials. Here, we illustrate that Hsp27 highly regulates the expression of the human DEAD-box protein 5 (DDX5), and we define DDX5 as a novel therapeutic target for CRPC treatment. DDX5 overexpression is strongly correlated with aggressive tumor features, notably with CRPC. DDX5 downregulation using a specific ASO-based inhibitor that acts on DDX5 mRNAs inhibits cell proliferation in preclinical models, and it particularly restores the treatment sensitivity of CRPC. Interestingly, through the identification and analysis of DDX5 protein interaction networks, we have identified some specific functions of DDX5 in CRPC that could contribute actively to tumor progression and therapeutic resistance. We first present the interactions of DDX5 and the Ku70/80 heterodimer and the transcription factor IIH, thereby uncovering DDX5 roles in different DNA repair pathways. Collectively, our study highlights critical functions of DDX5 contributing to CRPC progression and provides preclinical proof of concept that a combination of ASO-directed DDX5 inhibition with a DNA damage-inducing therapy can serve as a highly potential novel strategy to treat CRPC.

Splicing factor SRSF3 promotes the progression of cervical cancer through regulating DDX5

Aberrant alternative splicing (AS) profoundly affects tumorigenesis and cancer progression. Serine/arginine-rich splicing factor 3 (SRSF3) regulates the AS of precursor mRNAs and acts as a proto-oncogene in many tumors, but its function and potential mechanisms in cervical cancer remain unclear. Here, we found that SRSF3 was highly expressed in cervical cancer tissues and that SRSF3 expression was correlated with prognosis after analyses of the The Cancer Genome Atlas and GEO databases. Furthermore, knockdown of SRSF3 reduced the proliferation, migration, and invasion abilities of HeLa cells, while overexpression of SRSF3 promoted proliferation, migration, and invasion of CaSki cells. Further studies showed that SRSF3 mediated the variable splicing of exon 12 of the transcriptional cofactor DEAD-box helicase 5 (DDX5). Specifically, overexpression of SRSF3 promoted the production of the pro-oncogenic spliceosome DDX5-L and repressed the production of the repressive spliceosome DDX5-S. Ultimately, both SRSF3 and DDX5-L were able to upregulate oncogenic AKT expression, while DDX5-S downregulated AKT expression. In conclusion, we found that SRSF3 increased the production of DDX5-L and decreased the production of DDX5-S by regulating the variable splicing of DDX5. This, in turn promoted the proliferation, migration, and invasion of cervical cancer by upregulating the expression level of AKT. These results reveal the oncogenic role of SRSF3 in cervical cancer and emphasize the importance of the SRSF3-DDX5-AKT axis in tumorigenesis. SRSF3 and DDX5 are new potential biomarkers and therapeutic targets for cervical cancer.

Pan-cancer analysis of the prognostic and immunological roles of DEAD-box helicase 5 (DDX5) in human tumors

Background: Recent studies have demonstrated the significance of the DEAD-box helicase 5 (DDX5) gene, which is involved in pathways concerning the modification of RNA structures. DDX5 functions as a coregulator of cellular transcription and splicing, and participates in the processing of small noncoding RNAs. The aberrant regulation of DDX5 expression possibly plays a significant role in the genesis of cancer. However, there are no comprehensive pan-cancer studies on DDX5. This study is the first to conduct a pan-cancer analysis of DDX5 for aiding the diagnosis and treatment of cancer.

Methods: The gene expression, genetic alterations, protein phosphorylation, promoter methylation, immune infiltration, and enrichment analyses of DDX5 were performed using data retrieved from The Cancer Genome Atlas (TCGA), Genotype-tissue Expression (GTEx), Human Protein Atlas (HPA), Tumor Immunological Estimation Resource 2.0 (TIMER2.0), Gene Expression Profiling Interactive Analysis (GEPIA), DNA methylation interactive visualization database (DNMIVD), and Search Tool for the Retrieval of Interaction Genes/Proteins (STRING). Data analyses were performed with the R software and other webtools.

Results: The expression of DDX5 mRNA decreased significantly in 17 cancer types, but increased significantly in eight cancer types. The enhanced expression of DDX5 mRNA in the tumor samples was related to decreased overall survival (OS), progression-free interval (PFI), and disease-specific survival (DSS) in three cancers, but increased OS, PFI, and DSS in other cancers. The DNA promoter methylation level was significantly reduced in eight cancer types, and there were exceptions in the methylation levels of the DDX5 promoter in four cancer types. The expression of DDX5 mRNA was highly correlated with the infiltration of CD8+ T cells, cancer-associated fibroblasts, and B cells in a wide variety of malignancies. The findings revealed a strong association between DDX5 and its co-expressed genes in numerous cancer types. Enrichment analysis suggested that DDX5 was associated with multiple cellular pathways, including RNA splicing, Notch signaling pathway, and viral carcinogenesis, which was consistent with the results of previous studies.

Conclusion: The findings obtained herein provide further information on the oncogenic potential of DDX5 in diverse tumor types. We propose that DDX5 has important roles in tumor immunity and the diagnosis of cancer.

Construction of a 5-methylcytosine-Related Molecular Signature to Inform the Prognosis and Immunotherapy of Lung Squamous Cell Carcinoma

BACKGROUND

Methylation of cytosine residues resulting in 5-methylcytosine (5-mC) is an important epigenetic modification associated with tumorigenesis. The present study explored the relationship between methylation, prognosis, and immunotherapy of patients suffering from lung squamous cell carcinoma (LUSC).

METHODS

RNA sequencing data and corresponding clinical information were downloaded, and preprocessed, and unsupervised consistent cluster analysis was used to identify 5-mC-related clusters and gene clusters. 5-mC scores were calculated using principal component analysis, and a Boruta algorithm was used to evaluate the relationship between tumor mutation burden (TMB), immune checkpoint inhibitor response, and prognosis of individual LUSC patients.

RESULTS

: Two 5-mC clusters and three gene clusters with different prognoses were identified. Patients with higher 5-mC scores showed worse prognoses, which was confirmed in multiple cohorts. Some immune-related biological functions and pathways were enriched in the high-5-mC score subtype.

CONCLUSION

The 5-mC score is a potential biomarker independent of TMB, which can be a decisive factor regarding immune treatment responses. Further, patients with low 5-mC scores may respond better to immunotherapy. The 5-mC score can thus be used as a potential biomarker for the prognosis of LUSC patients and their response to immunotherapy.

Cell-cycle and apoptosis related and proteomics-based signaling pathways of human hepatoma Huh-7 cells treated by three currently used multi-RTK inhibitors

Sorafenib, lenvatinib and regorafenib, the multi-RTK inhibitors with potent anti-angiogenesis effects, are currently therapeutic drugs generally recommended for the patients with advanced hepatocellular carcinoma (HCC). To date, however, there have been no published studies on the mechanism underling differential effects of the three drugs on HCC cell proliferation, and the proteomic analysis in HCC cell lines treated by regorafenib or lenvatinib. The present study for the first time performed a direct comparison of the cell cycle arrest and apoptosis induction in the Huh-7 cells caused by sorafenib, regorafenib and lenvatinib at respective IC₅₀ using flow cytometry technique, as well as their pharmacological interventions for influencing whole cell proteomics using tandem mass tag-based peptide-labeling coupled with the nLC-HRMS technique. Sorafenib, regorafenib and lenvatinib at respective IC₅₀ drove the remaining surviving Huh-7 cells into a G₀/G₁ arrest, but lenvatinib and regorafenib were much more effective than sorafenib. Lenvatinib produced a much stronger induction of Huh-7 cells into early apoptosis than sorafenib and regorafenib, while necrotic cell proportion induced by regorafenib was 2.4 times as large as that by lenvatinib. The proteomic study revealed 419 proteins downregulated commonly by the three drugs at respective IC₅₀. KEGG pathway analysis of the downregulated proteins indicated the ranking of top six signaling pathways including the spliceosome, DNA replication, cell cycle, mRNA surveillance, P53 and nucleotide excision repair involved in 33 proteins, all of which were directly related to their pharmacological effects on cell cycle and cell apoptosis. Notably, lenvatinib and regorafenib downregulated the proteins of PCNA, Cyclin B1, BCL-xL, TSP1, BUD31, SF3A1 and Mad2 much more strongly than sorafenib. Moreover, most of the proteins in the P53 signaling pathway were downregulated with lenvatinib and regorafenib by more than 36% at least. In conclusion, lenvatinib and regorafenib have much stronger potency against Huh-7 cell proliferation than sorafenib because of their more potent effects on cell cycle arrest and apoptosis induction. The underling mechanism may be at least due to the 33 downregulated proteins centralizing the signal pathways of cell cycle, p53 and DNA synthesis based on the present proteomics study.

DEAD-Box RNA Helicases DDX3X and DDX5 as Oncogenes or Oncosuppressors: A Network Perspective

Simple Summary

The transformation of a normal cell into a cancerous one is caused by the deregulation of different metabolic pathways, involving a complex network of protein–protein interactions. The cellular enzymes DDX3X and DDX5 play important roles in the maintenance of normal cell metabolism, but their deregulation can accelerate tumor transformation. Both DDX3X and DDX5 interact with hundreds of different cellular proteins, and depending on the specific pathways in which they are involved, both proteins can either act as suppressors of cancer or as oncogenes. In this review, we summarize the current knowledge about the roles of DDX3X and DDX5 in different tumors. In addition, we present a list of interacting proteins and discuss the possible contribution of some of these protein–protein interactions in determining the roles of DDX3X and DDX5 in the process of cancer proliferation, also suggesting novel hypotheses for future studies.

Abstract

RNA helicases of the DEAD-box family are involved in several metabolic pathways, from transcription and translation to cell proliferation, innate immunity and stress response. Given their multiple roles, it is not surprising that their deregulation or mutation is linked to different pathological conditions, including cancer. However, while in some cases the loss of function of a given DEAD-box helicase promotes tumor transformation, indicating an oncosuppressive role, in other contexts the overexpression of the same enzyme favors cancer progression, thus acting as a typical oncogene. The roles of two well-characterized members of this family, DDX3X and DDX5, as both oncogenes and oncosuppressors have been documented in several cancer types. Understanding the interplay of the different cellular contexts, as defined by the molecular interaction networks of DDX3X and DDX5 in different tumors, with the cancer-specific roles played by these proteins could help to explain their apparently conflicting roles as cancer drivers or suppressors.

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.

Circular RNA dehydrodolichyl diphosphate synthase facilitated triple-negative breast cancer progression via miR-362-3p/DDX5 axis

BACKGROUND

Triple-negative breast cancer (TNBC) is a common hypotype of breast cancer. Circular RNAs (circRNAs) are burgeoning serve as vital controllers in numerous tumors. Nevertheless, the expression and regulatory mode of circRNAs in TNBC are still indistinct. This paper aimed to reveal the function and molecular mechanism of circular RNA dehydrodolichyl diphosphate synthase (circDHDDS) in TNBC.

METHODS

The contents of circDHDDS, DHDDS mRNA, microRNA-362-3p (miR-362-3p) and DEAD (Asp-Glu-Ala-Asp) box polypeptide 5 (DDX5) were indicated by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. The colony formation assay and 5-ethynyl-2'-deoxyuridine (EdU) assay were executed to assess cell proliferation. The flow cytometry assay was utilized to detect cell apoptosis. The transwell assay and tube formation assay were applied to measure cell migration, invasion and angiogenesis. The targeted relationships of miR-362-3p and circDHDDS or DDX5 were forecasted and detected by dual-luciferase reporter assay. The in vivo test was implemented to confirm the effect of circDHDDS.

RESULTS

The contents of circDHDDS and DDX5 were increased, and miR-362-3p level was decreased in TNBC. CircDHDDS deficiency reserved cell proliferation, migration, invasion and angiogenesis, while facilitated cell apoptosis in TNBC cells. Furthermore, miR-362-3p was validated to exert a tumor repressive effect in TNBC cells by suppressing DDX5. Moreover, DDX5 could regulate the development of TNBC. The experimental data exposed that levels of miR-362-3p presented noteworthy negative correlation with circDHDDS and DDX5, while circDHDDS and DDX5 exhibited significant positive correlation. In mechanism, circDHDDS bound to miR-362-3p to modulate DDX5 expression. In addition, circDHDDS knock-down also attenuated tumor growth.

CONCLUSION

CircDHDDS expedited TNBC by swelling DDX5 via adapting miR-362-3p.

Knockdown of KRAB domain-associated protein 1 suppresses the proliferation, migration and invasion of thyroid cancer cells by regulating P68/DEAD box protein 5

KRAB domain-associated protein 1 (KAP-1) has been reported to be an oncogene in diverse tumors. KAP-1 was found to have abundant existence in malignant thyroid tissues, but its role in thyroid cancer hasn’t been elucidated clearly. This study was carried out to explore the role of KAP-1 in thyroid cancer, and to clarify its molecular mechanism. The expressions of KAP-1 and P68/DEAD box protein 5 (DDX5) were assessed under the help of qRT-PCR and western blot. Then, we downregulated KAP-1 or upregulated DDX5 by cell transfection in TPC-1 cells. A series of cellular experiments on proliferation, apoptosis, migration and invasion were conducted with CCK-8, EdU, TUNEL, wound-healing and Transwell assays. Besides, the relationship between KAP-1 and DDX5 was verified by co-immunoprecipitation (Co-IP). The results showed that both of KAP-1 and DDX5 were upregulated in thyroid cancer cells. Loss-of-function experiments revealed that KAP-1 knockdown imparted suppressive effects on cell proliferation, migration and invasion, but promoted cell apoptosis. Additionally, KAP-1 was demonstrated to interact with DDX5 and positively regulate DDX5 expression. The following rescued experiments exhibited that the inhibitory effects of KAP-1 knockdown on cellular activities of thyroid cancer and Wnt/β-catenin signaling were also partly reversed by DDX5 overexpression. Moreover, activation of Wnt/β-catenin signaling retarded the anti-tumor activity of KAP-1 knockdown. In conclusion, the data in this study disclosed that KAP-1 silence helped to repress the cell proliferation, migration and invasion by degrading DDK5, so as to hinder the development of thyroid cancer.

DDX55 promotes HCC progression via interacting with BRD4 and participating in exosome-mediated cell-cell communication

The involvement of DEAD‐box helicase 55 (DDX55) in oncogenesis has been suggested, but its biological role in hepatocellular carcinoma (HCC) remains unknown. The present study verified the upregulation of DDX55 in HCC tissues compared with non‐tumor controls. DDX55 displayed the highest prognostic values among the DEAD‐box protein family for recurrence‐free survival and overall survival of HCC patients. In addition, the effects of DDX55 in the promotion of HCC cell proliferation, migration, and invasion were determined ex vivo and in vivo. Mechanistically, we revealed that DDX55 could interact with BRD4 to form a transcriptional regulatory complex that positively regulated PIK3CA transcription. Following that, β‐catenin signaling was activated in a PI3K/Akt/GSK‐3β dependent manner, thus inducing cell cycle progression and epithelial–mesenchymal transition. Intriguingly, both DDX55 mRNA and protein were identified in the exosomes derived from HCC cells. Exosomal DDX55 was implicated in intercellular communication between HCC cells with high or low DDX55 levels and between HCC cells and endothelial cells, thereby promoting the malignant phenotype of HCC cells and angiogenesis. In conclusion, DDX55 may be a valuable prognostic biomarker and therapeutic target in HCC.

FL118, acting as a 'molecular glue degrader', binds to dephosphorylates and degrades the oncoprotein DDX5 (p68) to control c-Myc, survivin and mutant Kras against colorectal and pancreatic cancer with high efficacy

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC), a difficult-to-treat cancer, is expected to become the second-largest cause of cancer-related deaths by 2030, while colorectal cancer (CRC) is the third most common cancer and the third leading cause of cancer deaths. Currently, there is no effective treatment for PDAC patients. The development of novel agents to effectively treat these cancers remains an unmet clinical need. FL118, a novel anticancer small molecule, exhibits high efficacy against cancers; however, the direct biochemical target of FL118 is unknown.

METHODS

FL118 affinity purification, mass spectrometry, Nanosep centrifugal device and isothermal titration calorimetry were used for identifying and confirming FL118 binding to DDX5/p68 and its binding affinity. Immunoprecipitation (IP), western blots, real-time reverse transcription PCR, gene silencing, overexpression (OE) and knockout (KO) were used for analysing gene/protein function and expression. Chromatin IP was used for analysing protein-DNA interactions. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromid assay and human PDAC/CRC cell/tumour models were used for determining PDAC/CRC cell/tumour in vitro and in vivo growth.

RESULTS

We discovered that FL118 strongly binds to dephosphorylates and degrades the DDX5 oncoprotein via the proteasome degradation pathway without decreasing DDX5 mRNA. Silencing and OE of DDX5 indicated that DDX5 is a master regulator for controlling the expression of multiple oncogenic proteins, including survivin, Mcl-1, XIAP, cIAP2, c-Myc and mutant Kras. Genetic manipulation of DDX5 in PDAC cells affects tumour growth. PDAC cells with DDX5 KO are resistant to FL118 treatment. Our human tumour animal model studies further indicated that FL118 exhibits high efficacy to eliminate human PDAC and CRC tumours that have a high expression of DDX5, while FL118 exhibits less effectiveness in PDAC and CRC tumours with low DDX5 expression.

CONCLUSION

DDX5 is a bona fide FL118 direct target and can act as a biomarker for predicting PDAC and CRC tumour sensitivity to FL118. This would greatly impact FL118 precision medicine for patients with advanced PDAC or advanced CRC in the clinic. FL118 may act as a 'molecular glue degrader' to directly glue DDX5 and ubiquitination regulators together to degrade DDX5.

Where all the Roads Meet? A Crossover Perspective on Host Factors Regulating SARS-CoV-2 infection

COVID-19 caused by SARS-CoV-2 is the latest pandemic which has thrown the world into an unprecedented social and economic uncertainties along with huge loss to humanity. Identification of the host factors regulating the replication of SARS-CoV-2 in human host may help in the development of novel anti-viral therapies to combat the viral infection and spread. Recently, some research groups used genome-wide CRISPR/Cas screening to identify the host factors critical for the SARS-CoV-2 replication and infection. A comparative analysis of these significant host factors (p < 0.05) identified fifteen proteins common in these studies. Apart from ACE2 (receptor for SARS-CoV-2 attachment), other common host factors were CSNK2B, GDI2, SLC35B2, DDX51, VPS26A, ARPP-19, C1QTNF7, ALG6, LIMA1, COG3, COG8, BCOR, LRRN2 and TLR9. Additionally, viral interactome of these host factors revealed that many of them were associated with several SARS-CoV-2 proteins as well. Interestingly, some of these host factors have already been shown to be critical for the pathogenesis of other viruses suggesting their crucial role in virus-host interactions. Here, we review the functions of these host factors and their role in other diseases with special emphasis on viral diseases.

Multiple functions of the DEAD-box RNA helicase, DDX5 (p68), make DDX5 a superior oncogenic biomarker and target for targeted cancer therapy

DDX5 (p68) is a well-known multifunctional DEAD-box RNA helicase and a transcription cofactor. Since its initial discovery more than three decades ago, DDX5 is gradually recognized as a potential biomarker and target for the treatment of various cancer types. Studies over the years significantly expanded our understanding of the functional diversity of DDX5 in various cancer types and extended our knowledge of its Mechanism of Action (MOA). This provides a rationale for the development of novel cancer therapeutics by using DDX5 as a biomarker and a therapeutic target. However, while most of the published studies have found DDX5 to be an oncogenic target and a cancer treatment-resistant biomarker, a few studies have reported that in certain scenarios, DDX5 may act as a tumor suppressor. After careful review of all the available relevant studies in the literature, we found that the multiple functions of DDX5 make it both a superior independent oncogenic biomarker and target for targeted cancer therapy. In this article, we will summarize the relevant studies on DDX5 in literature with a careful analysis and discussion of any inconsistencies encountered, and then provide our conclusions with respect to understanding the MOA of FL118, a novel small molecule. We hope that such a review will stimulate further discussion on this topic and assist in developing better strategies to treat cancer by using DDX5 as both an oncogenic biomarker and therapeutic target.

DEAD-Box RNA Helicases in Cell Cycle Control and Clinical Therapy

Cell cycle is regulated through numerous signaling pathways that determine whether cells will proliferate, remain quiescent, arrest, or undergo apoptosis. Abnormal cell cycle regulation has been linked to many diseases. Thus, there is an urgent need to understand the diverse molecular mechanisms of how the cell cycle is controlled. RNA helicases constitute a large family of proteins with functions in all aspects of RNA metabolism, including unwinding or annealing of RNA molecules to regulate pre-mRNA, rRNA and miRNA processing, clamping protein complexes on RNA, or remodeling ribonucleoprotein complexes, to regulate gene expression. RNA helicases also regulate the activity of specific proteins through direct interaction. Abnormal expression of RNA helicases has been associated with different diseases, including cancer, neurological disorders, aging, and autosomal dominant polycystic kidney disease (ADPKD) via regulation of a diverse range of cellular processes such as cell proliferation, cell cycle arrest, and apoptosis. Recent studies showed that RNA helicases participate in the regulation of the cell cycle progression at each cell cycle phase, including G1-S transition, S phase, G2-M transition, mitosis, and cytokinesis. In this review, we discuss the essential roles and mechanisms of RNA helicases in the regulation of the cell cycle at different phases. For that, RNA helicases provide a rich source of targets for the development of therapeutic or prophylactic drugs. We also discuss the different targeting strategies against RNA helicases, the different types of compounds explored, the proposed inhibitory mechanisms of the compounds on specific RNA helicases, and the therapeutic potential of these compounds in the treatment of various disorders.

LncRNA SNHG14 promotes cell proliferation and invasion in colorectal cancer through modulating miR-519b-3p/DDX5 axis

Numbers of studies suggest that long non-coding RNAs (lncRNAs) exert an important role in cancer progression. It is reported that lncRNA SNHG14 (SNHG14) promotes cell proliferation and invasion in many cancers. However, the underlying molecular mechanism of SNHG14 in colorectal cancer (CRC) remains unclear. In our study, we found that SNHG14 is highly expressed in CRC tissues and cells, especially in SW480 and HT-29 cells. In addition, sh-SNHG14 inhibits cell proliferation, cell migration and invasion, promotes cell apoptosis in CRC cell lines. Furthermore, we found that SNHG14 functions as a sponge for miR-519b-3p, while the DEAD box protein 5 (DDX5) is a downstream target gene of miR-519b-3p, and the functions of miR-519b-3p inhibitors on the CRC progression could be rescued by downregulation of DDX5. Our findings suggest that SNHG14 promotes the CRC progression by miR-519b-3p/DDX5 axis, implying the promising therapeutic target of SNHG4 for CRC patients.

DDX10 promotes human lung carcinoma proliferation by U3 small nucleolar ribonucleoprotein IMP4

Background

Lung cancer is a common tumor and a leading cause of death worldwide. DEAD/H box RNA helicases (DDX) include several family members which regulate mRNA translation in cancer cells. In this study, we demonstrated that DEAD/H box RNA helicase 10 (DDX10) was significantly upregulated in lung cancer tissues compared with adjacent nontumor tissues.

Methods

DDX10 expression was knocked down with shRNA in order to investigate the impact on A549 lung cancer cell growth and related molecular mechanisms in vitro and in vivo. DDX10 expression in lung cancer was assessed using online databases and patient samples.

Results

DDX10 knockdown significantly inhibited the proliferation of lung cancer cells in vitro and in vivo. Furthermore, the bioinformatic tool indicated the putative downstream protein U3 small nucleolar ribonucleoprotein 4 (IMP4). Our data showed a positive correlation between IMP4 and DDX10. We found that IMP4 overexpression could reverse the effect of DDX10 knockdown on the proliferation and apoptosis of A549 cells.

Conclusions

The findings of this study suggest that DDX10/IMP4 might be a novel target for lung cancer diagnosis and treatment.

DDX54 Plays a Cancerous Role Through Activating P65 and AKT Signaling Pathway in Colorectal Cancer

Colorectal cancer (CRC) is one of the most malignant cancers, and its incidence is still steadily increasing. The DDX RNA helicase family members have been found to play a role in various cancers; however, the role of DDX54 in colorectal cancer is still unclear and needed to be defined. Here, we found DDX54 was overexpressed in CRC tissues by the label-free mass spectrum, which was also verified in tissue microarray of colon cancer, as well as the CRC cell lines and TCGA database. High DDX54 level was correlated with tumor stage and distant metastasis, which always indicated a poor prognosis to the CRC patients. DDX54 could promote the proliferation and mobility of CRC cells through increasing the phosphorylation level p65 and AKT leading to the tumorigenesis. Here, we have preliminarily studied the function of DDX54 in CRC, which would improve our understanding of the underlying biology of CRC and provide the new insight that could be translated into novel therapeutic approaches.

Long non-coding RNA HOTAIR promotes hepatocellular carcinoma progression by regulating miR-526b-3p/DHX33 axis

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common human cancers. Long non-coding RNAs (lncRNAs) play pivotal roles in progression of various cancers, including HCC.

OBJECTIVE

We aimed to explore the exact role and underlying mechanism of lncRNA HOX transcript antisense intergenic RNA (HOTAIR) in HCC.

METHODS

Quantitative real time polymerase chain reaction (qRT-PCR) was carried out to determine the levels of HOTAIR, DEAH-box helicase 33 (DHX33) and miR-526b-3p. Western blot assay was used to detect the protein level of DHX33. Besides, cell proliferation and apoptosis were assessed by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and flow cytometry analysis, respectively. Cell migration and invasion were detected by transwell assay. The interaction between miR-526b-3p and HOTAIR or DHX33 was predicted by starbase and confirmed by the dual-luciferase reporter assay. Murine xenograft model was established through injecting Huh7 cells transfected with sh-NC or sh-HOTAIR.

RESULTS

The levels of HOTAIR and DHX33 were increased in HCC tissues and cells. Knockdown of either HOTAIR or DHX33 suppressed proliferation, migration and invasion but increased apoptosis in HCC cells. Moreover, DHX33 overexpression reversed the suppressive effect of HOTAIR knockdown on progression of HCC cells. Interestingly, miR-526b-3p could directly bind to HOTAIR, and DHX33 was a direct target of miR-526b-3p. Additionally, interference of HOTAIR restrained the tumor growth by upregulating miR-526b-3p and downregulating DHX33 in vivo.

CONCLUSIONS

HOTAIR knockdown suppressed cell proliferation, migration and invasion, and promoted apoptosis via regulating miR-526b-3p/DHX33 axis in HCC cells, providing a potential avenue for treatment of HCC.

Heat shock protein 90 promotes RNA helicase DDX5 accumulation and exacerbates hepatocellular carcinoma by inhibiting autophagy

OBJECTIVE

Hepatocellular carcinoma (HCC), the main type of liver cancer, has a high morbidity and mortality, and a poor prognosis. RNA helicase DDX5, which acts as a transcriptional co-regulator, is overexpressed in most malignant tumors and promotes cancer cell growth. Heat shock protein 90 (HSP90) is an important molecular chaperone in the conformational maturation and stabilization of numerous proteins involved in cell growth or survival.

METHODS

DDX5 mRNA and protein expression in surgically resected HCC tissues from 24 Asian patients were detected by quantitative real-time PCR and Western blot, respectively. The interaction of DDX5-HSP90 was determined by molecular docking, immunoprecipitation, and laser scanning confocal microscopy. The autophagy signal was detected by Western blot. The cell functions and signaling pathways of DDX5 were determined in 2 HCC cell lines. Two different murine HCC xenograft models were used to determine the function of DDX5 and the therapeutic effect of an HSP90 inhibitor.

RESULTS

HSP90 interacted directly with DDX5 and inhibited DDX5 protein degradation in the AMPK/ULK1-regulated autophagy pathway. The subsequent accumulation of DDX5 protein induced the malignant phenotype of HCC by activating the β-catenin signaling pathway. The silencing of DDX5 or treatment with HSP90 inhibitor both blocked in vivo tumor growth in a murine HCC xenograft model. High levels of HSP90 and DDX5 protein were associated with poor prognoses.

CONCLUSIONS

HSP90 interacted with DDX5 protein and subsequently protected DDX5 protein from AMPK/ULK1-regulated autophagic degradation. DDX5 and HSP90 are therefore potential therapeutic targets for HCC.

RNA Helicases as Shadow Modulators of Cell Cycle Progression

The progress of the cell cycle is directly regulated by modulation of cyclins and cyclin-dependent kinases. However, many proteins that control DNA replication, RNA transcription and the synthesis and degradation of proteins can manage the activity or levels of master cell cycle regulators. Among them, RNA helicases are key participants in RNA metabolism involved in the global or specific tuning of cell cycle regulators at the level of transcription and translation. Several RNA helicases have been recently evaluated as promising therapeutic targets, including eIF4A, DDX3 and DDX5. However, targeting RNA helicases can result in side effects due to the influence on the cell cycle. In this review, we discuss direct and indirect participation of RNA helicases in the regulation of the cell cycle in order to draw attention to downstream events that may occur after suppression or inhibition of RNA helicases.

The DEAD-box protein family of RNA helicases: sentinels for a myriad of cellular functions with emerging roles in tumorigenesis

DEAD-box RNA helicases comprise a family within helicase superfamily 2 and make up the largest group of RNA helicases. They are a profoundly conserved family of RNA-binding proteins, carrying a generic Asp-Glu-Ala-Asp (D-E-A-D) motif that gives the family its name. Members of the DEAD-box family of RNA helicases are engaged in all facets of RNA metabolism from biogenesis to decay. DEAD-box proteins ordinarily function as constituents of enormous multi-protein complexes and it is believed that interactions with other components in the complexes might be answerable for the various capacities ascribed to these proteins. Therefore, their exact function is probably impacted by their interacting partners and to be profoundly context dependent. This may give a clarification to the occasionally inconsistent reports proposing that DEAD-box proteins have both pro- and anti-proliferative functions in cancer. There is emerging evidence that DEAD-box family of RNA helicases play pivotal functions in various cellular processes and in numerous cases have been embroiled in cellular proliferation and/or neoplastic transformation. In various malignancy types, DEAD-box RNA helicases have been reported to possess pro-proliferation or even oncogenic roles as well as anti-proliferative or tumor suppressor functions. Clarifying the exact function of DEAD-box helicases in cancer is probably intricate, and relies upon the cellular milieu and interacting factors. This review aims to summarize the current data on the numerous capacities that have been ascribed to DEAD-box RNA helicases. It also highlights their diverse actions upon malignant transformation in the various tumor types.

Silencing of Long Non-Coding RNA FGD5-AS1 Inhibits the Progression of Non-Small Cell Lung Cancer by Regulating the miR-493-5p/DDX5 Axis

BACKGROUND

Long non-coding RNA FGD5 antisense RNA 1 (FGD5-AS1), identified to be a carcinogenic lncRNA, exhibits a regulatory role in some malignancies including non-small cell lung cancer (NSCLC). The aim of the present research is to decipher the function and underlying mechanism of FGD5-AS1 in progression of NSCLC.

METHODS

Expression of FGD5-AS1, miR-493-5p and DEAD-box protein 5 (DDX5) in NSCLC tissues and cells was quantified utilizing qRT-PCR. Cell proliferation was assessed by CCK-8 method. Scratch healing test and Transwell assay were used for assaying cell migration and invasion. Expressions of DDX5 and epithelial-mesenchymal transition (EMT)-related proteins were examined by Western blot. Additionally, targeting relationships between FGD5-AS1 and miR-493-5p, miR-493-5p and DDX5 were verified by dual-luciferase reporter gene assay.

RESULTS

Expression of FGD5-AS1 in NSCLC tissues and cell lines was up-regulated. Expression of FGD5-AS1 was in association with enlarged tumor size and lymph node metastasis of the patients. Knockdown of FGD5-AS1 led to the inhibition of proliferation, migration, invasion and EMT of NSCLC cells. FGD5-AS1 directly targeted miR-493-5p, while DDX5 was the target of miR-493-5p in NSCLC cells. Additionally, FGD5-AS1 could positively regulate the expression of DDX5 via suppressing miR-493-5p.

CONCLUSION

FGD5-AS1 facilitates the proliferation, migration, invasion and EMT of NSCLC cells by sponging miR-493-5p and up-regulating DDX5.

Lead DEAD/H box helicase biomarkers with the therapeutic potential identified by integrated bioinformatic approaches in lung cancer

DEAD/H box helicases are implicated in lung cancer but have not been systematically investigated for their clinical significance and function. In this study, we aimed to evaluate the potential of DEAD/H box helicases as prognostic biomarkers and therapeutic targets in lung cancer by integrated bioinformatic analysis of multivariate large-scale databases. Survival and differential expression analysis of these helicases enabled us to identify four biomarkers with the most significant alterations. These were found to be the negative prognostic factors DDX11, DDX55 and DDX56, and positive prognostic factor DDX5. Pathway enrichment analysis indicates that MYC signalling is negatively associated with expression levels of the DDX5 gene while positively associated with that of DDX11, DDX55 and DDX56. High expression levels of the DDX5 gene is associated with low mutation levels of TP53 and MUC16, the two most frequently mutated genes in lung cancer. In contrast, high expression levels of DDX11, DDX55 and DDX56 genes are associated with high levels of TP53 and MUC16 mutation. The tumour-infiltrated CD8 + T and B cells positively correlate with levels of DDX5 gene expression, while negatively correlate with that of the other three DEAD box helicases, respectively. Moreover, the DDX5-associated miRNA profile is distinguished from the miRNA profiles of DDX11, DDX55 and DDX56, although each DDX has a different miRNA signature. The identification of these four DDX helicases as biomarkers will be valuable for prognostic prediction and targeted therapeutic development in lung cancer.

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.

Endoxifen and fulvestrant regulate estrogen-receptor α and related DEADbox proteins

Breast cancer (BC) represents the most common type of cancer in females worldwide. Endocrine therapy evolved as one of the main concepts in treatment of hormone-receptor positive BC. Current research focuses on the elucidation of tumour resistance mechanisms against endocrine therapy. In a translational in vitro approach, potential regulatory effects of clinically implemented BC anti-oestrogens on ERα, its coactivators DDX5, DDX17 and other DEADbox proteins as well as on the proliferation markers cyclin D1 and Ki67 were investigated on both the RNA and protein level. BC in vitro models for hormone-receptor positive (MCF-7, T-47D) and hormone-receptor negative cells (BT-20) were subjected to endocrine therapy. Anti-oestrogen-dependent expression regulation of target genes on the transcriptional and translational level was quantified and statistically assessed. Endocrine therapy decreases the expression levels of Ki67, cyclin D1 and ERα in hormone-receptor positive cells. In the hormone-receptor negative cells, the three parameters remained stable after endocrine therapy. Endoxifen triggers a downregulation of DDX5 and DDX23 in MCF-7 cells. Fulvestrant treatment downregulates the expression levels of all investigated DEADbox proteins in MCF-7 cells. In T-47D cells, endoxifen and fulvestrant lead to a decrease of all target gene expression levels. Interestingly, endocrine therapy affects DEADbox RNA expression levels in BT-20 cells, too. However, this result could only be confirmed for DDX1, immunocytologically. The investigated DEADbox proteins appear to correlate with the oestrogen-dependent tumourigenesis in hormone-receptor positive BC and show expression alterations after endocrine treatment.

Identification of DHX36 as a tumour suppressor through modulating the activities of the stress-associated proteins and cyclin-dependent kinases in breast cancer

The nucleic acid guanine-quadruplex structures (G4s) are involved in many aspects of cancer progression. The DEAH-box polypeptide 36 (DHX36) has been identified as a dominant nucleic acid helicase which targets and disrupts DNA and RNA G4s in an ATP-dependent manner. However, the actual role of DHX36 in breast cancer remains unknown. In this study, we observed that the gene expression of DHX36 was positively associated with patient survival in breast cancer. The abundance of DHX36 is also linked with pathologic conditions and the stage of breast cancer. By using the xenograft mouse model, we demonstrated that the stable knockdown of DHX36 via lentivirus in breast cancer cells significantly promoted tumour growth. We also found that, after the DHX36 knockdown (KD), the invasion of triple-negative breast cancer cells was enhanced. In addition, we found a significant increase in the number of cells in the S-phase and a reduction of apoptosis with the response to cisplatin. DHX36 KD also desensitized the cytotoxic cellular response to paclitaxel and cisplatin. Transcriptomic profiling analysis by RNA sequencing indicated that DHX36 altered gene expression profile through the upstream activation of TNF, IFNγ, NFκb and TGFβ1. High throughput signalling analysis showed that one cluster of stress-associated kinase proteins including p53, ROCK1 and JNK were suppressed, while the mitotic checkpoint protein-serine kinases CDK1 and CDK2 were activated, as a consequence of the DHX36 knockdown. Our study reveals that DHX36 functions as a tumour suppressor and may be considered as a potential therapeutic target in breast cancer.

DDX5 promotes oncogene C3 and FABP1 expressions and drives intestinal inflammation and tumorigenesis

Tumorigenesis in different segments of the intestinal tract involves tissue-specific oncogenic drivers. In the colon, complement component 3 (C3) activation is a major contributor to inflammation and malignancies. By contrast, tumorigenesis in the small intestine involves fatty acid-binding protein 1 (FABP1). However, little is known of the upstream mechanisms driving their expressions in different segments of the intestinal tract. Here, we report that the RNA-binding protein DDX5 binds to the mRNA transcripts of C3 and Fabp1 to augment their expressions posttranscriptionally. Knocking out DDX5 in epithelial cells protected mice from intestinal tumorigenesis and dextran sodium sulfate (DSS)-induced colitis. Identification of DDX5 as a common upstream regulator of tissue-specific oncogenic molecules provides an excellent therapeutic target for intestinal diseases.

DDX5-targeting fully human monoclonal autoantibody inhibits proliferation and promotes differentiation of acute promyelocytic leukemia cells by increasing ROS production

Acute promyelocytic leukemia (APL) therapy involves the compounds cytotoxic to both malignant tumor and normal cells. Relapsed APL is resistant to subsequent chemotherapy. Novel agents are in need to kill APL cells selectively with minimal toxicity. DDX5 has been recognized to be a novel target to suppress acute myeloid leukemia (AML). However, the role of DDX5 remains elusive in APL. Here a DDX5-targeting fully human monoclonal autoantibody named after 2F5 was prepared. It is demonstrated that 2F5 selectively inhibited APL cell proliferation without toxicity to normal neutrophil and tissues. Moreover, 2F5 was confirmed to induce G0/G1 phase arrest in APL cells, and promote APL cell differentiation combined with decreased DDX5 expression and increased reactive oxygen species (ROS) production. Knockdown of DDX5 by siRNA also inhibited proliferation, promoted cell differentiation and enhanced ROS production in APL cells. However, the ROS inhibitor reversed the effects of 2F5 on DDX5 and ROS in APL cells. Thus, we conclude that DDX5-targeting 2F5 inhibits APL cell proliferation, and promotes cell differentiation via induction of ROS. 2F5 showed the therapeutic value of fully human monoclonal autoantibody in APL, which provides a novel and valid approach for treatment of relapse/refractory APL.

Silencing of p68 and STAT3 synergistically diminishes cancer progression

AIMS

Since several factors are involved in the tumorigenesis process, targeting only one factor most probably cannot overwhelm cancer progression. Therefore, it seems that combination therapy through targeting more than one cancer-related factor may lead to cancer control. The expression and function of p68 (DDX5; DEAD-Box Helicase 5) are dysregulated in various cancers. P68 is also a co-activator of many oncogenic transcription factors such as the signal transducer and activator of transcription-3 (STAT3), which contributes to cancer progression. This close connection between p68 and STAT3 plays an important role in the growth and development of cancer.

MATERIALS AND METHODS

We decided to suppress the p68/STAT3 axis in various cancer cells by using Polyethylene glycol-trimethyl Chitosan-Hyaluronic acid (PEG-TMC-HA) nanoparticles (NPs) loaded with siRNA molecules. We assessed the impact of this combination therapy on apoptosis, proliferation, angiogenesis, and tumor growth, both in vitro and in vivo.

KEY FINDINGS

The results showed that siRNA-loaded NPs notably suppressed the expression of p68/STAT3 axis in cancer cells, which was associated with blockade of tumor growth, colony formation, angiogenesis, and cancer cell migration. In addition to apoptosis induction, this combined therapy also reduced the expression of several tumor-promoting factors including Fibroblast growth factors (FGF), vascular endothelial growth factor (VEGF), transforming growth factor-β (TGF-β), matrix metallopeptidases-2 (MMP-2), MMP-9, hypoxia-inducible factor-(HIF-1α), interleukin-6 (IL-6), IL-33, Bcl-x, vimentin, and snail.

SIGNIFICANCE

These findings indicate the potential of this nano-based anti-cancer therapeutic strategy for efficient cancer therapy which should be further investigated in future studies.

DDX5 Silencing Suppresses the Migration of Basal cell Carcinoma Cells by Downregulating JAK2/STAT3 Pathway

Basal cell carcinoma is driven by the aberrant activation of hedgehog signaling. DEAD (Asp-Glu-Ala-Asp) box protein 5 is frequently overexpressed in human cancer cells and associated with the tumor growth and invasion. The purpose of this study was to investigate the role of DEAD (Asp-Glu-Ala-Asp) box protein 5 in the growth, migration, and invasion of basal cell carcinoma. The role of DEAD (Asp-Glu-Ala-Asp) box protein 5 was detected by quantitative real-time polymerase chain reaction, Western blot, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay in basal cell carcinoma cells. The associations between JAK2/STAT3 pathway and DEAD (Asp-Glu-Ala-Asp) box protein 5 were analyzed in basal cell carcinoma cells. Results showed that DEAD (Asp-Glu-Ala-Asp) box protein 5 is overexpressed in basal cell carcinoma cells. DEAD (Asp-Glu-Ala-Asp) box protein 5 knockdown inhibited the migration and invasion of basal cell carcinoma cells. DEAD (Asp-Glu-Ala-Asp) box protein 5 knockdown increased the apoptosis of basal cell carcinoma cells induced by tunicamycin. Results found that DEAD (Asp-Glu-Ala-Asp) box protein 5 knockdown increased JAK2 and STAT3 expression in basal cell carcinoma cells. JAK2 inhibitor decreased STAT3 expression and abolished the inhibitory effects of DEAD (Asp-Glu-Ala-Asp) box protein 5 silencing on migration and invasion in basal cell carcinoma cells. In conclusion, these results indicate that DEAD (Asp-Glu-Ala-Asp) box protein 5 is a potential target for inhibiting basal cell carcinoma cells growth, migration, and invasion by downregulating JAK2/STAT3 pathway.

LINC01116 promotes tumor proliferation and neutrophil recruitment via DDX5-mediated regulation of IL-1β in glioma cell

Tumor-associated neutrophils (TANs) are important inflammatory infiltrating cells in the tumor microenvironment and are closely related to the development of human tumor. However, the underlying mechanism of TANs recruiting to glioma remains unknown. Herein, we identified that LINC01116 was significantly upregulated in glioma, and positively correlated with clinical malignancy and survival prognosis. LINC01116 regulated the progression of glioma in vitro and in vivo. RNA-seq analysis demonstrated that LINC01116 knockdown affected the expression of IL-1β, which promoted glioma proliferation and neutrophil recruitment. Furthermore, the co-culture of glioma cells and neutrophils showed that the accumulation of TANs promoted tumor proliferation via producing a host of cytokines. Mechanistically, LINC01116 activated IL-1β expression by recruiting the transcriptional regulator DDX5 to the IL-1β promoter. Our findings reveal that LINC01116 can promote glioma proliferation and neutrophil recruitment by regulating IL-1β, and may be served as a novel target for glioma therapy and prognosis.

Knockdown of terminal differentiation induced ncRNA (TINCR) suppresses proliferation and invasion in hepatocellular carcinoma by targeting the miR-218-5p/DEAD-box helicase 5 (DDX5) axis

Terminal differentiation induced ncRNA (TINCR), a newly identified lncRNA, has been found to be associated with different human cancers including hepatocellular carcinoma (HCC). However, little is known regarding the pathological mechanisms of TINCR in HCC progression. In this study, we confirmed that TINCR expression was upregulated in HCC tumors and cell lines, and high TINCR expression was associated with larger tumor size, advanced tumor node metastasis stage, and poor prognosis. Functionally, knockdown of TINCR facilitated apoptosis and suppressed viability, colony formation and invasion in Huh7 and Hep3B cells. Mechanically, TINCR functioned as competing endogenous RNA (ceRNA) to regulate DEAD-box helicase 5 (DDX5) expression through sponging miR-218-5p. Moreover, the miR-218-5p expression was downregulated and DDX5 expression was upregulated in HCC tumors. The silencing of miR-218-5p or ectopic expression of DDX5 abated the tumor-suppressive effect of TINCR knockdown in vitro. Furthermore, si-TINCR-induced inactivation of AKT signaling was rescued by suppression of miR-218-5p or overexpression of DDX5. Also, the silencing of TINCR resulted in tumor growth inhibition in vivo. In summary, knockdown of TINCR suppressed HCC progression presumably by inactivation of AKT signaling through targeting the miR-218-5p/DDX5 axis, suggesting a novel TINCR/miR-218-5p/DDX5 pathway and therapy target for HCC.

Long Noncoding RNA NHEG1 Drives β-Catenin Transactivation and Neuroblastoma Progression through Interacting with DDX5

Recent studies suggest that long noncoding RNAs (lncRNAs) play essential roles in tumor progression. However, the functional roles and underlying mechanisms of lncRNAs in neuroblastoma (NB), the most common malignant solid tumor in pediatric population, still remain elusive. Herein, through integrating analysis of a public RNA sequencing dataset, neuroblastoma highly expressed 1 (NHEG1) was identified as a risk-associated lncRNA, contributing to an unfavorable outcome of NB. Depletion of NHEG1 led to facilitated differentiation and decreased growth and aggressiveness of NB cells. Mechanistically, NHEG1 bound to and stabilized DEAD-box helicase 5 (DDX5) protein through repressing proteasome-mediated degradation, resulting in β-catenin transactivation that altered target gene expression associated with NB progression. We further determined a lymphoid enhancer binding factor 1 (LEF1)/transcription factor 7-like 2 (TCF7L2)/NHEG1/DDX5/β-catenin axis with a positive feedback loop and demonstrated that NHEG1 harbored oncogenic properties via its interplay with DDX5. Administration of small interfering RNAs against NHEG1 or DDX5 reduced tumor growth and prolonged survival of nude mice bearing xenografts. High NHEG1 or DDX5 expression was associated with poor survival of NB patients. These results indicate that lncRNA NHEG1 exhibits oncogenic activity that affects NB progression via stabilizing the DDX5 protein, which might serve as a potential therapeutic target for NB.

LncRNA LINC00963 Promotes Tumorigenesis and Radioresistance in Breast Cancer by Sponging miR-324-3p and Inducing ACK1 Expression

Upregulation of long non-coding RNA LINC00963 has been observed in several cancer types. In this study, we analyzed the clinical and biological significance of LINC00963 in breast cancer. The key microRNA (miR) mediating the action of LINC00963 was identified. We show that LINC00963 upregulation is correlated with aggressive parameters of breast cancer. Silencing of LINC00963 suppresses the proliferation and tumorigenesis of breast cancer cells, whereas LINC00963 overexpression exerts an opposite effect. Knockdown of LINC00963 enhances DNA damage and oxidative stress and sensitizes breast cancer cells to radiation. Mechanistically, LINC00963 antagonizes the repressive activity of miR-324-3p on ACK1 expression. Clinically, there is a negative correlation between miR-324-3p and LINC00963 expression in breast cancer tissues. Overexpression of LINC00963 or ACK1 rescues the inhibitory effects of miR-324-3p on breast cancer cell proliferation and radiosensitivity. In addition, knockdown of ACK1 attenuates LINC00963-dependent breast cancer growth and tumorigenesis. Taken together, LINC00963 promotes tumorigenesis and radioresistance in breast cancer through interplay with miR-324-3p and derepression of ACK1. LINC00963 may represent a potential target for the treatment of breast cancer.