UNR/CSDE1 Expression Is Critical to Maintain Invasive Phenotype of Colorectal Cancer through Regulation of c-MYC and Epithelial-to-Mesenchymal Transition

CSDE1: a versatile regulator of gene expression in cancer

RNA-binding proteins (RBPs) have garnered significant attention in the field of cancer due to their ability to modulate diverse tumor traits. Once considered untargetable, RBPs have sparked renewed interest in drug development, particularly in the context of RNA-binding modulators of translation. This review focuses on one such modulator, the protein CSDE1, and its pivotal role in regulating cancer hallmarks. We discuss context-specific functions of CSDE1 in tumor development, its mechanisms of action, and highlight features that support its role as a molecular adaptor. Additionally, we discuss the regulation of CSDE1 itself and its potential value as biomarker and therapeutic target.

Identifying a core protein signature of small extracellular vesicles derived from B-cell precursor acute lymphoblastic leukaemia

Acute paediatric leukaemia is diagnosed and monitored via bone marrow aspirate assessment of blasts as a measure of minimal residual disease. Liquid biopsies in the form of blood samples could greatly reduce the need for invasive bone marrow aspirations, but there are currently no blood markers that match the sensitivity of bone marrow diagnostics. Circulating extracellular vesicles (EVs) represent candidate biomarkers that may reflect the blast burden in bone marrow, and several studies have reported on the utility of EVs as biomarkers for adult haematological malignancies. Increased levels of EVs have been reported for several haematological malignancies, and we similarly report here elevated EV concentrations in plasma from paediatric BCP-ALL patients. Plasma EVs are very heterogeneous in terms of their cellular origin, thus identifying a cancer selective EV-marker is challenging. Here, we undertook a reductionistic approach to identify protein markers selectively associated to plasma EVs derived from BCP-ALL patients. The EV proteome of primary BCP-ALL cell-derived EVs were compared against EVs from healthy donor B cells and the BCP-ALL cell line REH, and further against EVs isolated from plasma of healthy paediatric donors and paediatric BCP-ALL patients. With this approach, we identified a signature of 6 proteins (CD317, CD38, IGF2BP1, PCNA, CSDE1, and GPR116) that were specifically identified in BCP-ALL derived EVs only and not in healthy control EVs, and that could be exploited as diagnostic biomarkers.

RNA-Binding Proteins Regulate Post-Transcriptional Responses to TGF-β to Coordinate Function and Mesenchymal Activation of Murine Endothelial Cells

BACKGROUND

Endothelial cells (ECs) are primed to respond to various signaling cues. For example, TGF (transforming growth factor)-β has major effects on EC function and phenotype by driving ECs towards a more mesenchymal state (ie, triggering endothelial to mesenchymal activation), a dynamic process associated with cardiovascular diseases. Although transcriptional regulation triggered by TGF-β in ECs is well characterized, post-transcriptional regulatory mechanisms induced by TGF-β remain largely unknown.

METHODS

Using RNA interactome capture, we identified global TGF-β driven changes in RNA-binding proteins in ECs. We investigated specific changes in the RNA-binding patterns of hnRNP H1 (heterogeneous nuclear ribonucleoprotein H1) and Csde1 (cold shock domain containing E1) using RNA immunoprecipitation and overlapped this with RNA-sequencing data after knockdown of either protein for functional insight. Using a modified proximity ligation assay, we visualized the specific interactions between hnRNP H1 and Csde1 and target RNAs in situ both in vitro and in mouse heart sections.

RESULTS

Characterization of TGF-β-regulated RBPs (RNA-binding proteins) revealed hnRNP H1 and Csde1 as key regulators of the cellular response to TGF-β at the post-transcriptional level, with loss of either protein-promoting mesenchymal activation in ECs. We found that TGF-β drives an increase in binding of hnRNP H1 to its target RNAs, offsetting mesenchymal activation, but a decrease in Csde1 RNA-binding, facilitating this process. Both, hnRNP H1 and Csde1, dynamically bind and regulate specific subsets of mRNAs related to mesenchymal activation and endothelial function.

CONCLUSIONS

Together, we show that RBPs play a key role in the endothelial response to TGF-β stimulation at the post-transcriptional level and that the RBPs hnRNP H1 and Csde1 serve to maintain EC function and counteract mesenchymal activation. We propose that TGF-β profoundly modifies RNA-protein interaction entailing feedback and feed-forward control at the post-transcriptional level, to fine-tune mesenchymal activation in ECs.

Trap and ambush therapy using sequential primary and tumor escape-selective oncolytic viruses

In multiple models of oncolytic virotherapy, it is common to see an early anti-tumor response followed by recurrence. We have previously shown that frontline treatment with oncolytic VSV-IFN-β induces APOBEC proteins, promoting the selection of specific mutations that allow tumor escape. Of these mutations in B16 melanoma escape (ESC) cells, a C-T point mutation in the cold shock domain-containing E1 (CSDE1) gene was present at the highest frequency, which could be used to ambush ESC cells by vaccination with the mutant CSDE1 expressed within the virus. Here, we show that the evolution of viral ESC tumor cells harboring the escape-promoting CSDE1C-T mutation can also be exploited by a virological ambush. By sequential delivery of two oncolytic VSVs in vivo, tumors which would otherwise escape VSV-IFN-β oncolytic virotherapy could be cured. This also facilitated the priming of anti-tumor T cell responses, which could be further exploited using immune checkpoint blockade with the CD200 activation receptor ligand (CD200AR-L) peptide. Our findings here are significant in that they offer the possibility to develop oncolytic viruses as highly specific, escape-targeting viro-immunotherapeutic agents to be used in conjunction with recurrence of tumors following multiple different types of frontline cancer therapies.

Proteomics separates adult-type diffuse high-grade gliomas in metabolic subgroups independent of 1p/19q codeletion and across IDH mutational status

High-grade adult-type diffuse gliomas are malignant neuroepithelial tumors with poor survival rates in combined chemoradiotherapy. The current WHO classification is based on IDH1/2 mutational and 1p/19q codeletion status. Glioma proteome alterations remain undercharacterized despite their promise for a better molecular patient stratification and therapeutic target identification. Here, we use mass spectrometry to characterize 42 formalin-fixed, paraffin-embedded (FFPE) samples from IDH-wild-type (IDHwt) gliomas, IDH-mutant (IDHmut) gliomas with and without 1p/19q codeletion, and non-neoplastic controls. Based on more than 5,500 quantified proteins and 5,000 phosphosites, gliomas separate by IDH1/2 mutational status but not by 1p/19q status. Instead, IDHmut gliomas split into two proteomic subtypes with widespread perturbations, including aerobic/anaerobic energy metabolism. Validations with three independent glioma proteome datasets confirm these subgroups and link the IDHmut subtypes to the established proneural and classic/mesenchymal subtypes in IDHwt glioma. This demonstrates common phenotypic subtypes across the IDH status with potential therapeutic implications for patients with IDHmut gliomas.

Tumor Temperature: Friend or Foe of Virus-Based Cancer Immunotherapy

The temperature of a solid tumor is often dissimilar to baseline body temperature and, compared to healthy tissues, may be elevated, reduced, or a mix of both. The temperature of a tumor is dependent on metabolic activity and vascularization and can change due to tumor progression, treatment, or cancer type. Despite the need to function optimally within temperature-variable tumors, oncolytic viruses (OVs) are primarily tested at 37 °C in vitro. Furthermore, animal species utilized to test oncolytic viruses, such as mice, dogs, cats, and non-human primates, poorly recapitulate the temperature profile of humans. In this review, we discuss the importance of temperature as a variable for OV immunotherapy of solid tumors. Accumulating evidence supports that the temperature sensitivity of OVs lies on a spectrum, with some OVs likely hindered but others enhanced by elevated temperatures. We suggest that in vitro temperature sensitivity screening be performed for all OVs destined for the clinic to identify potential hinderances or benefits with regard to elevated temperature. Furthermore, we provide recommendations for the clinical use of temperature and OVs.

Significant position of C-myc in colorectal cancer: a promising therapeutic target

Colorectal cancer (CRC) is a malignant tumor initiating from the mucosa of the colorectum. According to the 2020 statistics from the World Health Organization, there are 10.0% CRC cases among all 19.3 million new cancers, followed by lung and breast cancer, and 9.4% CRC cases among all 9.9 million cancer deaths, ranking second. The population of CRC patients in China is large, and its incidence and mortality continue to increase each year. Despite the continuous development of surgical methods, chemotherapy, radiotherapy, targeted therapy and immunotherapy, the overall survival of CRC patients remains low. Past research has suggested that c-myc plays a pivotal role in the development of CRC. A higher expression level of c-Myc is a negative prognostic marker in CRC. However, there are few drugs targeting c-myc directly. Therefore, we focused on discovering the mechanism of c-myc in CRC to provide a reference for a better therapy choice for patients.

LINC01234 Accelerates the Progression of Breast Cancer via the miR-525-5p/Cold Shock Domain-Containing E1 Axis

Backgrounds. Long noncoding RNAs (lncRNAs) are strongly associated with the development of breast cancer (BC). As yet, the function of LINC01234 in BC remains unknown. Methods. Using biological information, the potential lncRNA, miRNA, and target gene were predicted. LINC01234 and miR-525-5p expression in BC tissues was detected using quantitative real-time reverse transcription polymerase chain reaction. Fluorescence in situ hybridization was used to determine the distribution of LINC01234. Cell proliferation was analyzed using CCK-8 assay, colony formation, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, and apoptosis evaluated using flow cytometry. Western blotting was used to evaluate protein expression. Dual-luciferase® reporter, RNA pull-down, and RNA immunoprecipitation assays were performed to analyze the binding relationships among LINC01234, miR-525-5p, and cold shock domain-containing E1 (CSDE1). Results. We screened out LINC01234, found to be significantly increased in BC tissues, associated with a poor prognosis, and positively correlated with tumor size of BC. Knockdown of LINC01234 suppressed BC cell growth and facilitated apoptosis. Dual-luciferase reporter®, RNA pull-down, and RNA immunoprecipitation assays confirmed that LINC01234 and CSDE1 directly interacted with miR-525-5p. Upregulation of miR-525-5p and suppression of CSDE1 inhibited BC cell growth and induced cell apoptosis. Conclusion. Upregulation of LINC01234 contributes to the development of BC through the miR-525-5p/CSDE1 axis. LINC01234 may be one of the potential diagnostic and treatment targets for BC.

Differences in gene expression despite identical histomorphology in sinonasal intestinal-type adenocarcinoma and metastases from colorectal adenocarcinoma

Sinonasal intestinal-type adenocarcinoma (sITAC) is histomorphologically indistinguishable from colorectal adenocarcinoma (CRC) leading to diagnostic challenges. Metastases from CRCs to the sinonasal tract have been reported. The aim of the study was to identify a biomarker making it possible to distinguish between sITAC and metastases of colorectal origin. Formalin-fixated paraffin-embedded (FFPE) tissue from 20 consecutive patients with sITAC treated at Rigshospitalet, Denmark from 2005 to 2017, 20 patients with CRC, and second patients with both sinonasal and colorectal carcinomas were included, and RNA-sequencing was performed on all samples. Moreover, a series of 26 samples from metastasizing CRC were included (in-house data). 3139 differentially expressed genes were identified, of these several were deemed as possible biomarkers, including CSDE1, for which immunohistochemical staining was performed. sITAC and CRC differ in genomic expression. CSDE1, previously found upregulated in CRC, was significantly differentially expressed. Using immunohistochemical staining, no sITACs displayed strong and diffuse staining for CSDE1, which represents a potential marker to use in distinguishing sITAC from a metastasis of colorectal origin. This knowledge could improve the diagnostic process and hopefully the outcome in patients with this rare tumor.

Advances in nanoparticle mediated targeting of RNA binding protein for cancer

RNA binding proteins (RBPs) enact a very crucial part in the RNA directive processes. Atypical expression of these RBPs affects many steps of RNA metabolism, majorly altering its expression. Altered expression and dysfunction of RNA binding proteins lead to cancer progression and other diseases. We enumerate various available interventions, and recent findings focused on targeting RBPs for cancer therapy and diagnosis. The treatment, sensitization, chemoprevention, gene-mediated, and virus mediated interventions were studied to treat and diagnose cancer. The application of passively and actively targeted lipidic nanoparticles, polymeric nanoparticles, virus-based particles, and vaccine-based immunotherapy for the delivery of therapeutic agent/s against cancer are discussed. We also discuss the formulation aspect of nanoparticles for achieving delivery at the site of action and ongoing clinical trials targeting RBPs.

Reduced miR-371b-5p expression drives tumor progression via CSDE1/RAC1 regulation in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer; however, specific prognostic biomarkers have not yet been developed. In this study, we identified dysregulated microRNAs (miRNAs) in TNBC by profiling miRNA and mRNA expression. In patients with TNBC, miR-371b-5p expression was reduced, and miR-371b-5p overexpression significantly mitigated TNBC cell growth, migration, and invasion. In addition, we found that expression of cold shock domain-containing protein E1 (CSDE1), a direct target gene of miR-371b-5p, was upregulated in TNBC cells, and inhibition of CSDE1 expression alleviated TNBC cell growth by regulating RAC1 transcription. Mechanistically, CSDE1, phosphorylated C-terminal domain (p-CTD) of RNA polymerase II (RNAPII), and CDK7 form a complex, and downregulation of CSDE1 leads to weak interaction between RNAPII p-CTD and CDK7, resulting in a decrease in RNAPII p-CTD expression to reduce RAC1 transcript levels in CSDE1-deficient TNBC cells. Our data demonstrate that miR-371b-5p is a tumor-suppressive miRNA that regulates the CSDE1/Rac1 axis and could be a potential prognostic biomarker for TNBC.

RNA-binding proteins and cancer metastasis

RNA-binding proteins (RBPs) can regulate gene expression through post-transcriptionally influencing all manner of RNA biology, including alternative splicing (AS), polyadenylation, stability, and translation of mRNAs, as well as microRNAs (miRNAs) and circular RNAs (circRNAs) processing. There is accumulating evidence reinforcing the perception that dysregulation or dysfunction of RBPs can lead to various human diseases, including cancers. RBPs influence diverse cancer-associated cellular phenotypes, such as proliferation, apoptosis, senescence, migration, invasion, and angiogenesis, contributing to the initiation and development of tumors, as well as clinical prognosis. Metastasis is the leading cause of cancer-related recurrence and death. Therefore, it is necessary to elucidate the molecular mechanisms behind tumor metastasis. In fact, a growing body of published research has proved that RBPs play pivotal roles in cancer metastasis. In this review, we will summarize the recent advances for helping us understand the role of RBPs in tumor metastasis, and discuss dysfunctions and dysregulations of RBPs affecting metastasis-associated processes including epithelial-mesenchymal transition (EMT), migration, and invasion of cancer cells. Furthermore, we will discuss emerging RBP-based strategy for the treatment of cancer metastasis.

Coordinated post-transcriptional control of oncogene-induced senescence by UNR/CSDE1

Oncogene-induced senescence (OIS) is a form of stable cell-cycle arrest arising in response to oncogenic stimulation. OIS must be bypassed for transformation, but the mechanisms of OIS establishment and bypass remain poorly understood, especially at the post-transcriptional level. Here, we show that the RNA-binding protein UNR/CSDE1 enables OIS in primary mouse keratinocytes. Depletion of CSDE1 leads to senescence bypass, cell immortalization, and tumor formation, indicating that CSDE1 behaves as a tumor suppressor. Unbiased high-throughput analyses uncovered that CSDE1 promotes OIS by two independent molecular mechanisms: enhancement of the stability of senescence-associated secretory phenotype (SASP) factor mRNAs and repression of Ybx1 mRNA translation. Importantly, depletion of YBX1 from immortal keratinocytes rescues senescence and uncouples proliferation arrest from the SASP, revealing multilayered mechanisms exerted by CSDE1 to coordinate senescence. Our data highlight the relevance of post-transcriptional control in the regulation of senescence.

Mesenchymal Stem Cell-derived Extracellular Vesicles Transmitting MicroRNA-34a-5p Suppress Tumorigenesis of Colorectal Cancer Through c-MYC/DNMT3a/PTEN Axis

Mesenchymal stem cell–derived extracellular vesicles (MSC-EV) can transport microRNAs (miRNAs) into colorectal cancer (CRC) cells, thus to inhibit the malignant phenotype of cancer cells. Whether MSC-EV could deliver miR-34a-5p to suppress CRC development was surveyed through the research. miR-34a-5p, c-MYC, DNA methyltransferase 3a (DNMT3a), and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression were measured in CRC tissues and cell lines. miR-34a-5p and c-MYC expression were altered by transfection in HCT-116 cells. MSC-EV were transfected with miR-34a-5p- and c-MYC-related oligonucleotides and co-cultured with HCT-116 cells. HCT-116 cell growth after treatment was observed. Furthermore, the functional roles of miR-34a-5p and c-MYC were explored in vivo. The combined interactions of miR-34a-5p/c-MYC/DNMT3a/PTEN axis were assessed. miR-34a-5p and PTEN were downregulated while c-MYC and DNMT3a were upregulated in CRC. Depletion of miR-34a-5p drove while that of c-MYC restricted CRC cell growth. MSC-EV retarded CRC progression. Moreover, MSC-EV carrying overexpressed miR-34a-5p or depleted c-MYC further disrupted CRC cell progression. miR-34a-5p targeted c-MYC to regulate DNMT3a and PTEN. c-MYC overexpression abrogated EV-derived miR-34a-5p upregulation-induced effects on CRC. Restoring miR-34a-5p or depleting c-MYC in MSC-EV limited CRC tumor formation. MSC-EV-derived miR-34a-5p depresses CRC development through modulating the binding of c-MYC to DNMT3a and epigenetically regulating PTEN.

Dynamic changes of plasma extracellular vesicle long RNAs during perioperative period of colorectal cancer

Extracellular vesicles (EVs) long RNAs (exLRs) have been shown to be indicators for the diagnosis and prognosis of colorectal cancer (CRC); however, the dynamic changes of exLRs during perioperative period and their cellular sources in CRC remains largely unknown. In this study, exLR sequencing (exLR-seq) was performed on plasma samples from three CRC patients at four time points (before surgery [T0], after extubation [T1], 1 day after surgery [T2], and 3 days after surgery [T3]). Bioinformatics approaches were used to investigate the profile and biofunctions of exLRs and their cellular sources. Greater than 12,000 mRNAs and 2,000 lncRNAs were reliably detected in each exLR-seq sample. Compared with T0, there were 110 differentially expressed genes (DEGs) in T1, 60 DEGs in T2, and 50 DEGs in T3. A total of 11 DEGs were found at all three time points and were related to membrane potential. In addition, compared to T0, 22 differentially expressed lncRNAs (DELRs) were found in T1, 19 DELRs in T2, and 38 DELRs in T3. Moreover, only three DELRs were detected at all three time points. Interestingly, EVs from CD8 + T cells, CD4+ memory T cells and NK cells decreased after surgery and the absolute quantity of EVs from immune cells were reduced as well. In summary, this study was the first to characterize the dynamic changes of exLRs during perioperative period and the cellular sources. These findings established the foundation for further studies involving the effects of these dynamically changed exLRs on CRC.

CSDE1 attenuates microRNA-mediated silencing of PMEPA1 in melanoma

MicroRNAs and RNA-binding proteins (RBPs) primarily target the 3' UTR of mRNAs to control their translation and stability. However, their co-regulatory effects on specific mRNAs in physiology and disease are yet to be fully explored. CSDE1 is an RBP that promotes metastasis in melanoma and mechanisms underlying its oncogenic activities need to be completely defined. Here we report that CSDE1 interacts with specific miRNA-induced silencing complexes (miRISC) in melanoma. We find an association of CSDE1 with AGO2, the essential component of miRISC, which is facilitated by target mRNAs and depends on the first cold shock domain of CSDE1. Both CSDE1 and AGO2 bind to 3' UTR of PMEPA1. CSDE1 counters AGO2 binding, leading to an increase of PMEPA1 expression. We also identify a miRNA, miR-129-5p, that represses PMEPA1 expression in melanoma. Collectively, our results show that PMEPA1 promotes tumorigenic traits and that CSDE1 along with miR-129-5p/AGO2 miRISC act antagonistically to fine-tune PMEPA1 expression toward the progression of melanoma.

Oncolytic virotherapy induced CSDE1 neo-antigenesis restricts VSV replication but can be targeted by immunotherapy

In our clinical trials of oncolytic vesicular stomatitis virus expressing interferon beta (VSV-IFNβ), several patients achieved initial responses followed by aggressive relapse. We show here that VSV-IFNβ-escape tumors predictably express a point-mutated CSDE1P5S form of the RNA-binding Cold Shock Domain-containing E1 protein, which promotes escape as an inhibitor of VSV replication by disrupting viral transcription. Given time, VSV-IFNβ evolves a compensatory mutation in the P/M Inter-Genic Region which rescues replication in CSDE1P5S cells. These data show that CSDE1 is a major cellular co-factor for VSV replication. However, CSDE1P5S also generates a neo-epitope recognized by non-tolerized T cells. We exploit this predictable neo-antigenesis to drive, and trap, tumors into an escape phenotype, which can be ambushed by vaccination against CSDE1P5S, preventing tumor escape. Combining frontline therapy with escape-targeting immunotherapy will be applicable across multiple therapies which drive tumor mutation/evolution and simultaneously generate novel, targetable immunopeptidomes associated with acquired treatment resistance.

A new horizon for the old antibacterial drug clofoctol

The synthetic antibacterial drug clofoctol (CFT) has long been used to treat respiratory tract infections in Europe. In recent years, the drug was found to target two biologically important proteins, the Cdc7/Dbf4 protein kinase complex and the mRNA-binding protein cold shock domain containing E1 (CSDE1), also known as upstream-of-N-Ras protein (UNR). These interactions are at the origin of the antitumor activity of CFT, recently evidenced in prostate cancer and neuroglioma. Drug-protein binding models provide a structural basis to guide the design of more potent anticancer compounds. A renewed interest in CFT can be anticipated for the treatment of cancers, and possibly Coronavirus 2019 (COVID-19).

Long non-coding RNA LINC00858 inhibits colon cancer cell apoptosis, autophagy, and senescence by activating WNK2 promoter methylation

Accumulating evidence shows the involvement of long non-coding RNAs (lncRNAs) in tumorigenesis of many types of human cancers. However, the role of LINC00858 in colon cancer has not been fully elucidated. Therefore, we investigated the involvement of LINC00858 in the progression of colon cancer and identified its downstream targets. After examining the expression of LINC00858 in colon cancer tissues and cell lines, we then identified the possible interaction between LINC00858 and WNK lysine deficient protein kinase 2 (WNK2) by fluorescence in situ hybridization, RNA immunoprecipitation, chromatin immunoprecipitation, and RNA pull-down assays. Next, the role of the LINC00858/WNK2 axis was explored by evaluating the apoptosis, autophagy, and senescence of colon cancer cells in vitro after ectopic expression and depletion experiments in HCT116 cells. Moreover, a mouse xenograft model of HCT116 cells was established to verify the function of the LINC00858/WNK2 axis in vivo. There was high expression of LINC00858 and low expression of WNK2 in colon cancer tissues and cell lines. Silencing of LINC00858 promoted apoptosis, senescence, and autophagy in colon cancer cells. Additionally, the enrichment of WNK2 was promoted when LINC00858 bound to DNA methyltransferases. Furthermore, in vivo assays demonstrated that silencing of LINC00858 resulted in inhibited tumor growth by upregulating WNK2. In summary, LINC00858 acts as a tumor-promoting lncRNA in colon cancer by downregulating WNK2. Our results may provide novel targets for the treatment for colon cancer.

RNA-binding proteins in tumor progression

RNA-binding protein (RBP) has a highly dynamic spatiotemporal regulation process and important biological functions. They are critical to maintain the transcriptome through post-transcriptionally controlling the processing and transportation of RNA, including regulating RNA splicing, polyadenylation, mRNA stability, mRNA localization, and translation. Alteration of each process will affect the RNA life cycle, produce abnormal protein phenotypes, and thus lead to the occurrence and development of tumors. Here, we summarize RBPs involved in tumor progression and the underlying molecular mechanisms whereby they are regulated and exert their effects. This analysis is an important step towards the comprehensive characterization of post-transcriptional gene regulation involved in tumor progression.

Cold Shock Domain Containing E1 (CSDE1) Protein is Overexpressed and Can be Targeted to Inhibit Invasiveness in Pancreatic Cancer Cells

Pancreatic cancer has a dismal prognosis and to date there are no targeted therapies for this malignancy. Using shotgun proteomics, the mRNA binding protein cold shock domain containing E1 (CSDE1), also called upstream-of-N-Ras, is detected in pancreatic cancer cell lines but not in normal pancreatic epithelial cells. The expression of CSDE1 in pancreatic cancer cells is confirmed by Western blotting and immunohistochemistry of human pancreatic tumors. In vitro functional assays show that siRNA downregulation of CSDE1 or gene knockout using CRISPR-Cas9 significantly reduce the invasiveness of pancreatic cancer cells. Together, this study reveals that CSDE1 is overexpressed in pancreatic cancer and is a potential therapeutic target to inhibit pancreatic cancer cell invasion.

The role of CSDE1 in translational reprogramming and human diseases

Abstract

CSDE1 (cold shock domain containing E1) plays a key role in translational reprogramming, which determines the fate of a number of RNAs during biological processes. Interestingly, the role of CSDE1 is bidirectional. It not only promotes and represses the translation of RNAs but also increases and decreases the abundance of RNAs. However, the mechanisms underlying this phenomenon are still unknown. In this review, we propose a “protein-RNA connector” model to explain this bidirectional role and depict its three versions: sequential connection, mutual connection and facilitating connection. As described in this molecular model, CSDE1 binds to RNAs and cooperates with other protein regulators. CSDE1 connects with different RNAs and their regulators for different purposes. The triple complex of CSDE1, a regulator and an RNA reprograms translation in different directions for each transcript. Meanwhile, a number of recent studies have found important roles for CSDE1 in human diseases. This model will help us to understand the role of CSDE1 in translational reprogramming and human diseases.

Post-transcriptional Regulation of Colorectal Cancer: A Focus on RNA-Binding Proteins

Colorectal cancer (CRC) is a major health problem with an estimated 1. 8 million new cases worldwide. To date, most CRC studies have focused on DNA-related aberrations, leaving post-transcriptional processes under-studied. However, post-transcriptional alterations have been shown to play a significant part in the maintenance of cancer features. RNA binding proteins (RBPs) are uprising as critical regulators of every cancer hallmark, yet little is known regarding the underlying mechanisms and key downstream oncogenic targets. Currently, more than a thousand RBPs have been discovered in humans and only a few have been implicated in the carcinogenic process and even much less in CRC. Identification of cancer-related RBPs is of great interest to better understand CRC biology and potentially unveil new targets for cancer therapy and prognostic biomarkers. In this work, we reviewed all RBPs which have a role in CRC, including their control by microRNAs, xenograft studies and their clinical implications.