Expression and prognostic value of Ars2 in hepatocellular carcinoma

Minnelide exhibits antileukemic activity by targeting the Ars2/miR-190a-3p axis

BACKGROUND

The identification of a novel and effective strategy for the clinical treatment of acute leukemia (AL) is a long-term goal. Minnelide, a water-soluble prodrug of triptolide, has recently been evaluated in phase I and II clinical trials in patients with multiple cancers and has shown promise as an antileukemic agent. However, the molecular mechanism underlying minnelide's antileukemic activity remains unclear.

PURPOSE

To explore the molecular mechanisms by which minnelide exhibits antileukemic activity.

METHODS

AL cells, primary human leukemia cells, and a xenograft mouse model were treated with triptolide and minnelide. The molecular mechanism was elucidated using western blotting, immunoprecipitation, flow cytometry, GSEA and liquid chromatography-mass spectrometry analysis.

RESULTS

Minnelide was highly effective in inhibiting leukemogenesis and improving survival in two complementary AL mouse models. Triptolide, an active form of minnelide, causes cell cycle arrest in G1 phase and induces apoptosis in both human AL cell lines and primary AL cells. Mechanistically, we identified Ars2 as a new chemotherapeutic target of minnelide for AL treatment. We found that triptolide directly targeted Ars2, resulting in the downregulation of miR-190a-3p, which led to the disturbance of PTEN/Akt signaling and culminated in G1 cell cycle arrest and apoptosis.

CONCLUSIONS

Our findings demonstrate that targeting Ars2/miR-190a-3p signaling using minnelide could represent a novel chemotherapeutic strategy for AL treatment and support the evaluation of minnelide for the treatment of AL in clinical trials.

RNA-binding proteins and exoribonucleases modulating miRNA in cancer: the enemy within

Recent progress in the investigation of microRNA (miRNA) biogenesis and the miRNA processing machinery has revealed previously unknown roles of posttranscriptional regulation in gene expression. The molecular mechanistic interplay between miRNAs and their regulatory factors, RNA-binding proteins (RBPs) and exoribonucleases, has been revealed to play a critical role in tumorigenesis. Moreover, recent studies have shown that the proliferation of hepatocellular carcinoma (HCC)-causing hepatitis C virus (HCV) is also characterized by close crosstalk of a multitude of host RBPs and exoribonucleases with miR-122 and its RNA genome, suggesting the importance of the mechanistic interplay among these factors during the proliferation of HCV. This review primarily aims to comprehensively describe the well-established roles and discuss the recently discovered understanding of miRNA regulators, RBPs and exoribonucleases, in relation to various cancers and the proliferation of a representative cancer-causing RNA virus, HCV. These have also opened the door to the emerging potential for treating cancers as well as HCV infection by targeting miRNAs or their respective cellular modulators.

The Carcinogenic Potential of Bisphenol A in the Liver Based on Transcriptomic Studies

Bisphenol A (BPA) is an environmental toxin widely used in the production of polycarbonate plastics. A correlation exists between BPA tissue contamination and the occurrence of pathological conditions, including cancer. First-passage detoxification of high BPA amounts in the liver promotes hepatotoxicity and morphological alterations of this organ, but there is a lack of knowledge about the molecular mechanisms underlying these phenomena. This prompted us to investigate changes in the liver transcriptomics of 3-month-old female mice exposed to BPA (50 mg/kg) in drinking water for 3 months. Five female mice served as controls. The animals were euthanized, the livers were collected, and RNA was extracted to perform RNA-seq analysis. The multistep transcriptomic bioinformatics revealed 120 differentially expressed genes (DEGs) in the BPA-exposed samples. Gene Ontology (GO) annotations indicated that DEGs have been assigned to many biological processes, including "macromolecule modification" and "protein metabolic process". Several of the revealed DEGs have been linked to the pathogenesis of severe metabolic liver disorders and malignant tumors, in particular hepatocellular carcinoma. Data from this study suggest that BPA has a significant impact on gene expression in the liver, which is predictive of the carcinogenic potential of this compound in this organ.

Serrate RNA Effector Molecule (SRRT) Is Associated with Prostate Cancer Progression and Is a Predictor of Poor Prognosis in Lethal Prostate Cancer

Arsenite-resistance protein 2, also known as serrate RNA effector molecule (ARS2/SRRT), is known to be involved in cellular proliferation and tumorigenicity. However, its role in prostate cancer (PCa) has not yet been established. We investigated the potential role of SRRT in 496 prostate samples including benign, incidental, advanced, and castrate-resistant patients treated by androgen deprivation therapy (ADT). We also explored the association of SRRT with common genetic aberrations in lethal PCa using immunohistochemistry (IHC) and performed a detailed analysis of SRRT expression using The Cancer Genome Atlas (TCGA PRAD) by utilizing RNA-seq, clinical information (pathological T category and pathological Gleason score). Our findings indicated that high SRRT expression was significantly associated with poor overall survival (OS) and cause-specific survival (CSS). SRRT expression was also significantly associated with common genomic aberrations in lethal PCa such as PTEN loss, ERG gain, mutant TP53, or ATM. Furthermore, TCGA PRAD data revealed that high SRRT mRNA expression was significantly associated with higher Gleason scores, PSA levels, and T pathological categories. Gene set enrichment analysis (GSEA) of RNAseq data from the TCGA PRAD cohort indicated that SRRT may play a potential role in regulating the expression of genes involved in prostate cancer aggressiveness. Conclusion: The current data identify the SRRT's potential role as a prognostic for lethal PCa, and further research is required to investigate its potential as a therapeutic target.

Arsenic resistance protein 2 and microRNA biogenesis: Biological implications in cancer development

Arsenic resistance protein 2 (Ars2) is a nuclear protein that plays a critical role in the regulation of microRNA (miRNA) biogenesis. Ars2 is required for cell proliferation and for the early stages of mammalian development through a possible effect on miRNA processing. Increasing evidence reveal that Ars2 is highly expressed in proliferating cancer cells, suggesting that Ars2 may be a potential therapeutic target for cancer. Therefore, development of the novel Ars2 inhibitors could represent the novel therapeutic strategies for treatment of cancer. In this review, we briefly discuss the mechanisms by which Ars2 regulates miRNA biogenesis and its impact on cell proliferation and cancer development. Particularly, we mainly discuss the role of Ars2 in the regulation of cancer development and highlight pharmacological targeting of Ars2 as a promising cancer therapeutic strategy.

Identification of Three Key Genes Associated with Hepatocellular Carcinoma Progression Based on Co-expression Analysis

Hepatocellular carcinoma (HCC) is the fifth most common cancer and one of the leading causes of cancer-related death in the world. Due to the recurrence of HCC, its survival rate is still low. Therefore, it is vital to seek prognostic biomarkers for HCC. In this study, differential analysis was conducted on gene expression data in The Cancer Genome Atlas -LIHC, and 4482 differentially expressed genes in tumor tissue were selected. Then, weighted gene co-expression network analysis was used to analyze the co-expression of the gained differential genes. By module-trait correlation analysis, the turquoise gene module that was significantly related to tumor grade, pathologic_T stage, and clinical stage was identified. Thereafter, enrichment analysis of genes in this module uncovered that the genes were mainly enriched in the signaling pathways involved in spliceosome and cell cycle. After that, through correlation analysis, 18 hub genes highly correlated with tumor grade, clinical stage, pathologic_T stage, and the turquoise module were selected. Meanwhile, protein-protein interaction (PPI) network was constructed by using genes in the module. Finally, three key genes, heterogeneous nuclear ribonucleoprotein L, serrate RNA effector molecule, and cyclin B2, were identified by intersecting the top 30 genes with the highest connectivity in PPI network and the previously obtained 18 hub genes in the turquoise module. Further survival analysis revealed that high expression of the three key genes predicted poor prognosis of HCC. These results indicated the direction for further research on clinical diagnosis and prognostic biomarkers of HCC.

Identification of the atypically modified autoantigen Ars2 as the target of B-cell receptors from activated B-cell-type diffuse large B-cell lymphoma

It has been suggested that stimulation of B-cell receptors (BCR) by specific antigens plays a pathogenic role in diffuse large B-cell lymphoma (DLBCL). Here, it was the aim to screen for specific reactivities of DLBCL-BCR in the spectrum of autoantigens and antigens of infectious origin. Arsenite resistance protein 2 (Ars2) was identified as the BCR target of three of five activated B-cell type DLBCL cell lines and two of 11 primary DLBCL cases. Compared to controls, Ars2 was hypophosphorylated exclusively in cases and cell lines with Ars2-specific BCR. In a validation cohort, hypophosphorylated Ars2 was found in eight of 31 activated B-cell type DLBCL, but in only one of 20 germinal center B-cell like type DLBCL. Incubation with Ars2 induced BCR-pathway activation and increased proliferation, while an Ars2/ETA’ toxin conjugate induced killing of cell lines with Ars2-reactive BCR. Ars2 appears to play a role in a subgroup of activated B-cell-type DLBCL. Moreover, transformed DLBCL lines with Ars2-reactive BCR still showed growth advantage after incubation with Ars2. These results provide knowledge about the pathogenic role of a specific antigen stimulating the BCR pathway in DLCBL.

ARS2/SRRT: at the nexus of RNA polymerase II transcription, transcript maturation and quality control

ARS2/SRRT is an essential eukaryotic protein that has emerged as a critical factor in the sorting of functional from non-functional RNA polymerase II (Pol II) transcripts. Through its interaction with the Cap Binding Complex (CBC), it associates with the cap of newly made RNAs and acts as a hub for competitive exchanges of protein factors that ultimately determine the fate of the associated RNA. The central position of the protein within the nuclear gene expression machinery likely explains why its depletion causes a broad range of phenotypes, yet an exact function of the protein remains elusive. Here, we consider the literature on ARS2/SRRT with the attempt to garner the threads into a unifying working model for ARS2/SRRT function at the nexus of Pol II transcription, transcript maturation and quality control.

Depletion of Ars2 inhibits cell proliferation and leukemogenesis in acute myeloid leukemia by modulating the miR-6734-3p/p27 axis

Ars2 is a component of the nuclear cap-binding complex (CBC) that contributes to microRNA biogenesis and is required for cellular proliferation. Little is known regarding the functional role of Ars2 in cell proliferation and leukemogenesis of acute myeloid leukemia. Here, we show that the elevated expression of Ars2 was observed in acute myeloid leukemia (AML) cell lines and bone marrow samples from AML patients and was correlated with poorer overall survival. Overexpression of Ars2 promoted cell proliferation and colony formation in AML cells, whereas depletion of Ars2 inhibited cell proliferation and colony formation. Mechanistic studies reveal that depletion of Ars2 suppressed the interaction of Ars2 with CBC and led to alterations in miRNA processing. Furthermore, Ars2 depletion reduced the levels of miR-6734-3p, resulting in upregulation of p27 and culminating in cell cycle arrest at the G1 phase. In vivo studies indicate that depletion of Ars2 significantly reduced leukemic cell burden and prolonged the survival time of the leukemia-bearing mice. These findings indicate that Ars2 may not only play a crucial role in the regulation of cell proliferation and leukemogenesis, but could also be identified as a critical therapeutic target for treatment of AML.

Knockdown of arsenic resistance protein 2 inhibits human glioblastoma cell proliferation through the MAPK/ERK pathway

It is generally known that glioblastoma is the most common primary malignant brain tumor and that it is highly aggressive and deadly. Although surgical and pharmacological therapies have made long‑term progress, glioblastoma remains extremely lethal and has an uncommonly low survival rate. Therefore, further elucidation of the molecular mechanisms of glioblastoma initiation and its pathological processes are urgent. Arsenic resistance protein 2 (Ars2) is a highly conserved gene, and it has been found to play an important role in microRNA biosynthesis and cell proliferation in recent years. Furthermore, absence of Ars2 results in developmental death in Drosophila, zebrafish and mice. However, there are few studies on the role of Ars2 in regulating tumor development, and the mechanism of its action is mostly unknown. In the present study, we revealed that Ars2 is involved in glioblastoma proliferation and we identified a potential mechanistic role for it in cell cycle control. Our data demonstrated that Ars2 knockdown significantly repressed the proliferation and tumorigenesis abilities of glioblastoma cells in vitro and in vivo. Further investigation clarified that Ars2 deficiency inhibited the activation of the MAPK/ERK pathway, leading to cell cycle arrest in the G1 phase, resulting in suppression of cell proliferation. These findings support the conclusion that Ars2 is a key regulator of glioblastoma progression.

Ars2 promotes cell proliferation and tumorigenicity in glioblastoma through regulating miR-6798-3p

Arsenic resistance protein 2 (Ars2) is a component of the nuclear RNA cap-binding complex (CBC) that is important for some microRNA biogenesis and it is critical for cell proliferation and tumorigenicity. However, mechanism of Ars2-regulated cellular proliferation and tumorigenicity in glioblastoma has not been fully understood. Western blotting was used to detect the expressions of Ars2, p53, p21, and cleavage/activation of caspases-3 (C-Caspase 3). Microarray and Quantitative Real-time PCR (qRT-PCR) were performed to identify the Ars2-regulated microRNAs. Apoptosis assessed by flow cytometry analysis was used to evaluate the role of Ars2 in cells proliferation. The lentivirus-mediated gene knockdown approach was conducted to determine the function of Ars2. The orthotopic glioblastoma xenograft was used to demonstrate the role of Ars2 in glioblastoma growth in vivo. The high expression of Ars2 was observed in several glioblastoma cell lines and was significantly associated with poorer overall survival. Importantly, the overexpression of Ars2 promoted cell proliferation and colony formation in glioblastoma cells, whereas the depletion of Ars2 inhibited cell proliferation, colony formation, and tumor growth. Mechanistic study revealed that knockdown of Ars2 reduced the expression levels of miR-6798-3p, which was responsible for the up-regulation of p53 and p21, leading to apoptosis. Furthermore, the knockdown of Ars2 suppressed tumor growth in orthotopic glioblastoma xenograft model and significantly prolonged the survival time of the tumor-bearing mice. These findings identify a critical role for Ars2 in regulation of proliferation and tumorigenicity in glioblastoma and suggest that Ars2 could be a critical therapeutic target for glioblastoma intervention.