RNA-binding proteins in regulating mRNA stability and translation: roles and mechanisms in cancer

The regulatory roles of RNA-binding proteins in the tumour immune microenvironment of gastrointestinal malignancies

The crosstalk between the tumour immune microenvironment (TIME) and tumour cells promote immune evasion and resistance to immunotherapy in gastrointestinal (GI) tumours. Post-transcriptional regulation of genes is pivotal to GI tumours progression, and RNA-binding proteins (RBPs) serve as key regulators via their RNA-binding domains. RBPs may exhibit either anti-tumour or pro-tumour functions by influencing the TIME through the modulation of mRNAs and non-coding RNAs expression, as well as post-transcriptional modifications, primarily N6-methyladenosine (m6A). Aberrant regulation of RBPs, such as HuR and YBX1, typically enhances tumour immune escape and impacts prognosis of GI tumour patients. Further, while targeting RBPs offers a promising strategy for improving immunotherapy in GI cancers, the mechanisms by which RBPs regulate the TIME in these tumours remain poorly understood, and the therapeutic application is still in its early stages. This review summarizes current advances in exploring the roles of RBPs in regulating genes expression and their effect on the TIME of GI tumours, then providing theoretical insights for RBP-targeted cancer therapies.

Emerging regulatory mechanisms and functions of biomolecular condensates: implications for therapeutic targets

Cells orchestrate their processes through complex interactions, precisely organizing biomolecules in space and time. Recent discoveries have highlighted the crucial role of biomolecular condensates-membrane-less assemblies formed through the condensation of proteins, nucleic acids, and other molecules-in driving efficient and dynamic cellular processes. These condensates are integral to various physiological functions, such as gene expression and intracellular signal transduction, enabling rapid and finely tuned cellular responses. Their ability to regulate cellular signaling pathways is particularly significant, as it requires a careful balance between flexibility and precision. Disruption of this balance can lead to pathological conditions, including neurodegenerative diseases, cancer, and viral infections. Consequently, biomolecular condensates have emerged as promising therapeutic targets, with the potential to offer novel approaches to disease treatment. In this review, we present the recent insights into the regulatory mechanisms by which biomolecular condensates influence intracellular signaling pathways, their roles in health and disease, and potential strategies for modulating condensate dynamics as a therapeutic approach. Understanding these emerging principles may provide valuable directions for developing effective treatments targeting the aberrant behavior of biomolecular condensates in various diseases.

S100A16 stabilizes the ITGA3‑mediated ECM‑receptor interaction pathway to drive the malignant properties of lung adenocarcinoma cells via binding MOV10

Lung adenocarcinoma (LUAD) is highly associated with lung cancer‑associated mortality. Notably, S100 calcium‑binding protein A16 (S100A16) has been increasingly considered to have prognostic value in LUAD; however, the underlying mechanism remains unknown. In the present study, S100A16 expression levels in LUAD tissues and cells were respectively analyzed by the UALCAN database and western blotting. Cell Counting Kit‑8 and 5‑ethynyl‑2'‑deoxyuridine assays were used to examine cell proliferation, whereas wound healing, Transwell and tube formation assays were used to assess cell migration, invasion and angiogenesis, respectively. Western blotting was also used to examine the expression levels of proteins associated with metastasis, angiogenesis, focal adhesion and the extracellular matrix (ECM)‑receptor interaction pathways. The relationship between S100A16 and Mov10 RNA helicase (MOV10) was predicted by bioinformatics tools, and was verified using a co‑immunoprecipitation assay. Furthermore, the interaction between MOV10 and integrin α3 (ITGA3) was verified by RNA immunoprecipitation assay, and the actinomycin D assay was used to detect ITGA3 mRNA stability. The results demonstrated that S100A16 expression was increased in LUAD tissues and cell lines, and was associated with unfavorable outcomes. Knocking down S100A16 expression hindered the proliferation, migration, invasion and angiogenesis of LUAD cells. Furthermore, S100A16 was shown to bind to MOV10 and positively modulate MOV10 expression in LUAD cells, while MOV10 overexpression partially reversed the suppressive role of S100A16 knockdown on the aggressive phenotypes of LUAD cells. Furthermore, it was demonstrated that S100A16 regulated the stability of ITGA3 mRNA via MOV10 to mediate ECM‑receptor interactions. In conclusion, S100A16 may bind to MOV10 to stabilize ITGA3 mRNA and regulate ECM‑receptor interactions, hence contributing to the malignant progression of LUAD.

A positive feedback loop of SRSF9/USP22/ZEB1 promotes the progression of ovarian cancer

Ovarian cancer (OC) is recognized as the most lethal type of gynecological malignancy, making treatment options challenging. Discovering novel therapeutic targets will benefit OC patients. This study aimed to reveal the mechanism by which SRSF9 regulates OC progression. Cell proliferation was determined via CCK-8 assays, whereas cell migration and invasion were monitored via Transwell assays. Western blotting and qPCR assays were used to detect protein and mRNA alterations. RNA pull-down, RNA immunoprecipitation (RIP), and actinomycin D experiments were performed to investigate the relationships between SRSF9 and USP22. Co-IP was used to validate the interaction between USP22 and ZEB1. Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays were used to verify the regulatory effect of ZEB1 on the transcription of SRSF9. Subcutaneous xenograft models were established to evaluate the impact of SRSF9 on tumor development. Knockdown of SRSF9 significantly suppressed the proliferation, invasion, migration, tumorigenicity, and epithelial‒mesenchymal transition (EMT) of OC cells. SRSF9 can bind to USP22 mRNA, increasing its stability. Moreover, the overexpression of USP22 reversed the impact of SRSF9 silencing on malignant phenotypes. USP22 can mediate the deubiquitination of ZEB1, thereby enhancing the progression of OC. Furthermore, ZEB1 upregulated SRSF9 expression through transcriptional activation, thus establishing a positive feedback loop. SRSF9 enhanced the malignant characteristics of OC through a positive feedback loop of SRSF9/USP22/ZEB1. This functional circuit may help in the development of novel therapeutic approaches for treating OC.

A review of the complex interplay between chemoresistance and lncRNAs in lung cancer

Lung Cancer (LC) is characterized by chemoresistance, which poses a significant clinical challenge and results in a poor prognosis for patients. Long non-coding RNAs (lncRNAs) have recently gained recognition as crucial mediators of chemoresistance in LC. Through the regulation of key cellular processes, these molecules play important roles in the progression of LC and response to therapy. The mechanisms by which lncRNAs affect chemoresistance include the modulation of gene expression, chromatin structure, microRNA interactions, and signaling pathways. Exosomes have emerged as key mediators of lncRNA-driven chemoresistance, facilitating the transfer of resistance-associated lncRNAs between cancer cells and contributing to tumor development. Consequently, exosomal lncRNAs may serve as biomarkers and therapeutic targets for the treatment of LC. Therapeutic strategies targeting lncRNAs offer novel approaches to circumvent chemoresistance. Different approaches, including RNA interference (RNAi) and antisense oligonucleotides (ASOs), are available to degrade lncRNAs or alter their function. ASO-based therapies are effective at reducing lncRNA expression levels, increasing chemotherapy sensitivity, and improving clinical outcomes. The use of these strategies can facilitate the development of targeted interventions designed to disrupt lncRNA-mediated mechanisms of chemoresistance. An important aspect of this review is the discussion of the complex relationship between lncRNAs and drug resistance in LC, particularly through exosomal pathways, and the development of innovative therapeutic strategies to enhance drug efficacy by targeting lncRNAs. The development of new pathways and interventions for treating LC holds promise in overcoming this resistance.

Crispr-cas biosensing for rapid detection of viral infection

With the frequent outbreaks of viral diseases globally, accurate and rapid diagnosis of viral infections is of significant importance for disease prevention and control. The CRISPR-Cas combined biosensing strategy, as an emergent nucleic acid detection technology, exhibits notable advantages including high specificity, elevated sensitivity, operational simplicity, and cost-effectiveness, thereby demonstrating significant potential in the domain of rapid viral diagnostics. This paper summarizes the principles of the CRISPR-Cas system, the novel biotechnologies, and the latest research progress in virus detection using the combined biosensing strategy. Additionally, this paper discusses the challenges faced by CRISPR-Cas biosensing strategies and outlines future development directions, which provides a reference for further research and clinical applications in the rapid diagnosis of viral infections.

Inhibiting intracellular CD28 in cancer cells enhances antitumor immunity and overcomes anti-PD-1 resistance via targeting PD-L1

Deciphering mechanisms for cancer immune escape may provide targets for improving immunotherapy efficacy. By in vivo genome-wide CRISPR loss-of-function screening in a mouse model of triple negative breast cancer (TNBC), we uncovered a non-classical function of Cd28 in cancer cells to promote immune escape. Knocking out Cd28 in cancer cells increased infiltration of type I conventional DC (cDC1) and activated tumor-specific CD8+ T cells, and pharmaceutical inducible knockdown of Cd28 inhibited pre-established tumor growth and overcame anti-PD-1 resistance in vivo. Furthermore, high expression of cancer cell CD28 in human TNBC tissues correlated with elevated PD-L1 expression, less CD8+ T cell infiltration, and poor prognosis. Mechanistically, intracellular CD28 directly bound to Cd274 mRNA and recruited spliceosomal factor SNRPB2 to stabilize Cd274 mRNA in nucleus, promoting PD-L1 expression and immune escape. Therefore, disrupting cancer cell CD28-mediated immune escape may provide a potential approach to improve breast cancer immunotherapy.

LARP1, an RNA-binding protein, participates in ovarian cancer cell survival by regulating mitochondrial oxidative phosphorylation in response to the influence of the PI3K/mTOR pathway

Targeting the PI3K/mTOR pathway and modulating mitochondrial adaptation is expected to be a critical approach for cancer therapy. Although the regulation of mitochondria by the PI3K/mTOR pathway has been investigated, it is not well understood due to the complexity of its regulatory mechanisms. RNA-binding proteins (RBPs) selectively regulate gene expression through post-transcriptional modulation, playing a key role in cancer progression. LARP1, a downstream RBP of the mTOR pathway, is involved in mitochondria-mediated BCL-2 cell survival. Therefore, exploring the involvement of LARP1 in PI3K/mTOR-mediated translational regulation of mitochondria-associated proteins in ovarian cancer cells could help elucidate the role of mitochondria in the PI3K/mTOR pathway. We found that, unlike SKOV3 cells, the mitochondrial function of A2780 cells was not affected, which were insensitive to the dual PI3K/mTOR inhibitor PKI-402, suggesting that cell survival may be related to mitochondrial function. Knockdown of the LARP1 gene after PKI-402 treatment resulted in impaired mitochondrial function in A2780 cells, possibly due to decreased mRNA stability and reduced protein translation of the mitochondrial transcription initiation factor, TFB2M, and the respiratory chain complex II subunit, SDHB. LARP1 affects protein translation by binding to TFB2M mRNA, regulating mitochondrial DNA-encoded genes, or indirectly regulating the nuclear DNA-encoded SDHB gene, ultimately interfering with mitochondrial oxidative phosphorylation and leading to apoptosis. Therefore, LARP1 may be an important mediator in the PI3K/mTOR pathway for regulating mRNA translation and mitochondrial function. Targeting RBPs such as LARP1 downstream of the mTOR pathway may provide new insights and potential therapeutic approaches for ovarian cancer treatment.

Identification of RNA-binding protein genes associated with renal rejection and graft survival

Rejection is one of the major factors affecting the long-term prognosis of kidney transplantation, and timely recognition and aggressive treatment of rejection is essential to prevent disease progression. RBPs are proteins that bind to RNA to form ribonucleoprotein complexes, thereby affecting RNA stability, processing, splicing, localization, transport, and translation, which play a key role in post-transcriptional gene regulation. However, their role in renal transplant rejection and long-term graft survival is unclear. The aim of this study was to comprehensively analyze the expression of RPBs in renal rejection and use it to construct a robust prediction strategy for long-term graft survival. The microarray expression profiles used in this study were obtained from GEO database. In this study, a total of eight hub RBPs were identified, all of which were upregulated in renal rejection samples. Based on these RBPs, the renal rejection samples could be categorized into two different clusters (cluster A and cluster B). Inflammatory activation in cluster B and functional enrichment analysis showed a strong association with rejection-related pathways. The diagnostic prediction model had a high diagnostic accuracy for T cell mediated rejection (TCMR) in renal grafts (area under the curve = 0.86). The prognostic prediction model effectively predicts the prognosis and survival of renal grafts (p < .001) and applies to both rejection and non-rejection situations. Finally, we validated the expression of hub genes, and patient prognosis in clinical samples, respectively, and the results were consistent with the above analysis.

Glucose-induced LINC01419 reprograms the glycolytic pathway by recruiting YBX1 to enhance PDK1 mRNA stability in hepatocellular carcinoma

Metabolic reprogramming provides the necessary energy for the development of malignant tumours and is emerging as a novel tumour treatment strategy. However, the widespread expression of metabolic enzymes in diverse cell types makes the development of specific drugs that target cancer cells without affecting normal cellular functions challenging. Accumulating evidence has demonstrated the essential roles of long non-coding RNAs (lncRNAs) in the regulatory network associated with glucose metabolism in tumour cells. The mechanism and therapeutic potential of cancer-specific lncRNAs in modulating tumour glucose metabolism warrant in-depth exploration. Here we revealed that glucose-induced LINC01419 promoted the growth and metastasis of HCC cells by driving metabolic reprogramming. Mechanistically, LINC01419 directly interacted with Y-box binding protein 1 (YBX1) in the cytoplasm and facilitated its binding to PDK1 mRNA, thus enhancing PDK1 mRNA stability and increasing lactate production. Furthermore, YY1 contributed to the transcriptional activation of LINC01419 in HCC under high-glucose conditions. Notably, administration of an N-acetylgalactosamine (GalNAc)-conjugated siRNA specifically targeting LINC01419 markedly retarded the growth of orthotopic xenograft tumours. These findings provide evidence for an unprecedented regulatory mechanism of LINC01419 involving metabolic reprogramming in human cancer. The newly identified LINC01419/YBX1-PDK1 axis may represent a promising therapeutic target for HCC. Moreover, GalNAc-siLINC01419 holds significant potential for clinical application. KEY POINTS: This study highlights the considerable regulatory role of LINC01419 in the metabolism of HCC. The newly identified LINC01419/YBX1-PDK1 axis constitutes a valuable target. Hepatic-specific delivery of GalNAc-siLINC01419 presents a promising therapeutic strategy for HCC.

RNA binding protein RBM22 suppresses non-small cell lung cancer tumorigenesis by stabilizing LATS1 mRNA

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related mortality worldwide. Despite advancements in diagnostics and therapeutics, the prognosis for NSCLC remains poor, highlighting the urgent need for novel treatment options. RNA binding proteins, particularly RBM22, have emerged as significant contributors to cancer progression by influencing RNA splicing and gene expression. This study investigates the role of RBM22 in NSCLC and its potential as a therapeutic target. We focus on the effects of RBM22 on cell proliferation, invasion, stemness, and its interaction with LATS1 mRNA. RBM22 expression was assessed in samples and cell lines of NSCLC through techniques such as real-time PCR and western blot analysis. To modify RBM22 levels, overexpression and knockdown methods were employed utilizing vectors and siRNAs. We conducted assays for cell proliferation, invasion, and stemness to evaluate the effects of altering RBM22. The interaction between RBM22 and LATS1 mRNA was investigated using RNA immunoprecipitation. In addition, in vivo studies involving subdermal tumor and lung metastasis models in athymic mice were carried out to evaluate how changes in RBM22 influence the tumorigenic and metastatic characteristics of NSCLC. Our analysis revealed a significant underexpression of RBM22 in NSCLC tissues compared to adjacent healthy tissues. Increasing RBM22 expression in NSCLC cell lines led to a marked decrease in cellular proliferation, invasiveness, and stemness, while silencing RBM22 produced opposing effects. Further investigations confirmed that RBM22 directly interacts with LATS1 mRNA, thereby stabilizing and enhancing its expression. In vivo studies validated that elevated RBM22 expression substantially reduced tumor formation and pulmonary metastases, as evidenced by decreased tumor size, mass, and Ki-67 proliferation marker expression, along with a significant reduction in the number of metastatic nodules in the lungs. Our study demonstrates that RBM22 suppresses NSCLC by stabilizing LATS1 mRNA, which in turn reduces tumor growth and metastasis. Consequently, RBM22 emerges as a valuable therapeutic target for NSCLC, offering new strategies for addressing this challenging condition.

CELF6 as an Oncogene in Colorectal Cancer: Targeting Stem-Cell-Like Properties Through Modulation of HOXA5 mRNA Stability

BACKGROUND

Emerging evidence indicates the essential role of cancer stem cells (CSCs) in the development and progression of various cancers, including colorectal cancer (CRC). CELF6, a member of the cytosine-uridine-guanine-binding protein (CUG-BP), Elav-like family (CELF), has been reported to be downregulated in CRC tissues. This study aims to elucidate the role and underlying mechanisms of CELF6 in CRC progression.

METHODS

The expression levels and prognostic significance of CELF6, along with its association with homeobox A5 (HOXA5), were analyzed using University of Alabama at Birmingham Cancer Data Analysis Portal (UALCAN), PrognoScan, and Tumor Immune Estimation Resource (TIMER) databases. The expression of CELF6 was further assessed through quantitative real-time polymerase chain reaction (qRT-PCR), immunoblotting, and immunohistochemistry. Both in vitro and in vivo experiments were conducted to investigate the effects of CELF6 on CRC cell proliferation, stemness and tumorigenesis, and to elucidate the molecular mechanisms.

RESULTS

CELF6 was found to be downregulated in CRC and was associated with poor prognosis. Functional studies revealed that overexpression of CELF6 resulted in decreased CRC cell proliferation and stemness in vitro, reduced tumor growth in vivo, and induced G1 phase cell cycle arrest. Mechanistically, CELF6 regulated the expression of HOXA5 by modulating its mRNA stability. Furthermore, the knockdown of HOXA5 reversed the inhibitory effects of CELF6 on CRC cell proliferation and stemness, demonstrating that silencing HOXA5 counteracted the suppressive effects of CELF6.

CONCLUSIONS

This study is the first to identify CELF6 as a suppressor of stemness and a modulator of CRC progression. These findings provide new insights into the role of CELF6 in CRC and highlight its potential as a novel therapeutic target.

The noncanonical RNA-binding protein RAN stabilizes the mRNA of intranuclear stress granule assembly factor G3BP1 in nasopharyngeal carcinoma

RNA-binding proteins (RBPs) play critical roles in tumor progression by participating in the posttranscriptional regulation of RNA. However, the levels and function of RBPs in nasopharyngeal carcinoma (NPC) remain elusive. Here we identified a noncanonical RBP RAN that has the most significant role in NPC progression by a small siRNA pool screening. Functionally, RAN facilitates NPC proliferation and metastasis in vitro and in vivo. High levels of RAN are associated with poor prognosis of NPC patients and can be performed as a prognostic biomarker. Mechanistically, RAN increases the nucleus import of TDP43 and enhances TDP43 nuclear distribution. On the other hand, RAN is directly bound to the coding sequence of G3BP1 mRNA and serves as an adapter to facilitate TDP43 interacting with G3BP1 mRNA 3' UTR. These contribute to increasing G3BP1 mRNA stability in the nucleus and lead to upregulation of G3BP1, which further enhances AKT and ERK signaling and ultimately promotes NPC proliferation and metastasis. These findings reveal that RAN stabilizes intranuclear G3BP1 mRNA by dual mechanisms: recruiting TDP43 into the nucleus and enhancing its interaction with G3BP1 mRNA, suggesting a critical role of RAN in NPC progression and providing a new regulation framework of RBP-RNA.

The role of lncRNA binding to RNA‑binding proteins to regulate mRNA stability in cancer progression and drug resistance mechanisms (Review)

Cancer is a disease that poses a serious threat to human health, the occurrence and development of which involves complex molecular mechanisms. Long non‑coding RNAs (lncRNAs) and RNA‑binding proteins (RBPs) are important regulatory molecules within cells, which have garnered extensive attention in cancer research in recent years. The binding of lncRNAs and RBPs plays a crucial role in the post‑transcriptional regulation of mRNA, affecting the synthesis of proteins related to cancer by regulating the stability of mRNA. This, in turn, regulates the malignant biological behaviors of tumor cells, such as proliferation and metastasis, and serves an important role in therapeutic resistance. The present study reviewed the role of lncRNA‑RBP interactions in the regulation of mRNA stability in various malignant tumors, with a focus on the molecular mechanisms underlying this regulatory interaction. The aim of the present review was to gain a deeper understanding of these molecular mechanisms to provide new strategies and insights for the precise treatment of cancer.

hnRNPAB Promotes Pancreatic Ductal Adenocarcinoma Extravasation and Liver Metastasis by Stabilizing MYC mRNA

Heterogeneous nuclear ribonucleoprotein AB (hnRNPAB) is considered a cancer-promoting heterogeneous nuclear ribonucleoprotein in many cancers, but its function in pancreatic ductal adenocarcinoma (PDAC) is poorly understood. hnRNPAB was highly expressed in PDAC tissues compared with normal pancreatic tissues, and high expression of hnRNPAB was associated with poor overall survival and recurrence-free survival in patients with PDAC. hnRNPAB promotes migration and invasion of PDAC cells in vitro. In xenograft tumor mouse models, hnRNPAB deprivation significantly attenuated liver metastasis. hnRNPAB mRNA and protein levels are positively associated with MYC in PDAC cells. Mechanistically, hnRNPAB bound to MYC mRNA and prolonged its half-life. hnRNPAB induced PDAC cells to secrete CXCL8 via MYC, which promoted neutrophil recruitment and facilitated tumor cells entrancing into the hepatic parenchyma. These findings point to a novel regulatory mechanism via which hnRNPAB promotes PDAC metastasis. Implications: hnRNPAB participates in the posttranscriptional regulation of the oncogene MYC by binding and stabilizing MYC mRNA, thereby promoting liver metastasis in PDAC.

HNRNPC modulates PKM alternative splicing via m6A methylation, upregulating PKM2 expression to promote aerobic glycolysis in papillary thyroid carcinoma and drive malignant progression

The heterogeneous nuclear ribonucleoprotein C (HNRNPC) plays a crucial role in tumorigenesis, yet its role in papillary thyroid carcinoma (PTC) remains elusive. Herein, we elucidated the function and molecular mechanism of HNRNPC in PTC tumorigenesis and progression. Our study unveiled a significant upregulation of HNRNPC in PTC, and knockdown of HNRNPC markedly inhibited the proliferation, invasion, and metastasis of BCPAP cells. Furthermore, HNRNPC modulated PKM alternative splicing in BCPAP cells primarily through m6A modification. Additionally, by upregulating PKM2 expression, HNRNPC promoted aerobic glycolysis in BCPAP cells, thereby facilitating malignant progression in PTC. In summary, our findings demonstrate that HNRNPC regulates PKM alternative splicing through m6A methylation modification and promotes the proliferation, invasion and metastasis of PTC through glucose metabolism pathways mediated by PKM2. These discoveries provide new biomarkers for screening and diagnosing PTC patients and offer novel therapeutic targets for personalized treatment strategies.

Integrated multi-omics analysis of zinc-finger proteins uncovers roles in RNA regulation

RNA interactome studies have revealed that hundreds of zinc-finger proteins (ZFPs) are candidate RNA-binding proteins (RBPs), yet their RNA substrates and functional significance remain largely uncharacterized. Here, we present a systematic multi-omics analysis of the DNA- and RNA-binding targets and regulatory roles of more than 100 ZFPs representing 37 zinc-finger families. We show that multiple ZFPs are previously unknown regulators of RNA splicing, alternative polyadenylation, stability, or translation. The examined ZFPs show widespread sequence-specific RNA binding and preferentially bind proximal to transcription start sites. Additionally, several ZFPs associate with their targets at both the DNA and RNA levels. We highlight ZNF277, a C2H2 ZFP that binds thousands of RNA targets and acts as a multi-functional RBP. We also show that ZNF473 is a DNA/RNA-associated protein that regulates the expression and splicing of cell cycle genes. Our results reveal diverse roles for ZFPs in transcriptional and post-transcriptional gene regulation.

Global RNA Interaction and Transcriptome Profiles Demonstrate the Potential Anti-Oncogenic Targets and Pathways of RBM6 in HeLa Cells

BACKGROUND

The fate and functions of RNAs are coordinately regulated by RNA-binding proteins (RBPs), which are often dysregulated in various cancers. Known as a splicing regulator, RNA-binding motif protein 6 (RBM6) harbors tumor-suppressor activity in many cancers; however, there is a lack of research on the molecular targets and regulatory mechanisms of RBM6.

METHODS

In this study, we constructed an RBM6 knock-down (shRBM6) model in the HeLa cell line to investigate its functions and molecular targets. Then we applied improved RNA immunoprecipitation coupled with sequencing (iRIP-seq) and whole transcriptome sequencing approaches to investigate the potential role and RNA targets of RBM6.

RESULTS

Using The Cancer Genome Atlas dataset, we found that higher expression of RBM6 is associated with a better prognosis in many cancer types. In addition, we found that RBM6 knockdown promoted cell proliferation and inhibited apoptosis, demonstrating that RBM6 may act as an anti-oncogenic protein in cancer cells. RBM6 can regulate the alternative splicing (AS) of genes involved in DNA damage response, proliferation, and apoptosis-associated pathways. Meanwhile, RBM6 knockdown activated type I interferon signaling pathways and inhibited the expression of genes involved in the cell cycle, cellular responses to DNA damage, and DNA repair pathways. The differentially expressed genes (DEGs) by shRBM6 and their involved pathways were likely regulated by the transcription factors undergoing aberrant AS by RBM6 knockdown. For iRIP-seq analysis, we found that RBM6 could interact with a large number of mRNAs, with a tendency for binding motifs GGCGAUG and CUCU. RBM6 bound to the mRNA of cell proliferation- and apoptosis-associated genes with dysregulated AS after RBM6 knockdown.

CONCLUSIONS

In summary, our study highlights the important role of RBM6, as well as the downstream targets and regulated pathways, suggesting the potential regulatory mechanisms of RBM6 in the development of cancer.

Genome-Wide Mapping of RNA-Protein Associations via Sequencing

RNA-protein interactions are crucial for regulating gene expression and cellular functions, with their dysregulation potentially impacting disease progression. Systematically mapping these interactions is resource-intensive due to the vast number of potential RNA and protein interactions. Here, we introduce PRIM-seq (Protein-RNA Interaction Mapping by sequencing), a method for the concurrent de novo identification of RNA-binding proteins (RBPs) and the elucidation of their associated RNAs. PRIM-seq works by converting each RNA-protein pair into a unique chimeric DNA sequence, which is then decoded through DNA sequencing. Applied to two human cell types, PRIM-seq generated a comprehensive human RNA-protein association network (HuRPA), consisting of more than 350,000 RNA-proteins pairs involving approximately 7,000 RNAs and 11,000 proteins. The data revealed an enrichment of previously reported RBPs and RNA-protein interactions within HuRPA. We also identified LINC00339 as a protein-associating non-coding RNA and PHGDH as an RNA-associating protein. Notably, PHGDH interacts with BECN1 and ATF4 mRNAs, suppressing their protein expression and consequently inhibiting autophagy, apoptosis, and neurite outgrowth while promoting cell proliferation. PRIM-seq offers a powerful tool for discovering RBPs and RNA-protein associations, contributing to more comprehensive functional genome annotations.

Oncofetal TRIM71 drives liver cancer carcinogenesis through remodeling CEBPA-mediated serine/glycine metabolism

Rationale: Tumor cells remodel transcriptome to construct an ecosystem with stemness features, which maintains tumor growth and highly malignant characteristics. However, the core regulatory factors involved in this process still need to be further discovered. Methods: Single cell RNA-sequncing (scRNA-seq) and bulk RNA-sequencing profiles derived from fetal liver, normal liver, liver tumors, and their adjacent samples were collected to analyze the ecosystem of liver cancer. Mouse models were established to identify molecular functions of oncofetal-related oncogenes using hydrodynamic tail vein injection. Results: We found that liver cancer rebuilt oncofetal ecosystem to maintain malignant features. Interestingly, we identified a group of RNA-binding proteins (RBPs) that were highly overexpressed with oncofetal features. Among them, TRIM71 was specifically expressed in liver cancers and was associated with poor outcomes. TRIM71 drove the carcinogenesis of hepatocellular carcinoma (HCC), and knockdown of TRIM71 significantly abolished liver cancer cell proliferation. Mechanistically, TRIM71 formed a protein complex with IGF2BP1, bound to and stabilized the mRNA of CEBPA in an m6A-dependent manner, enhance the serine/glycine metabolic pathway, and ultimately promoted liver cancer progression. Furthermore, we identified that all-trans-retinoic acid (ATRA) combined with e1A binding protein p300 (EP300) inhibitor A-485 repressed TRIM71, attenuated glycine/serine metabolism, and inhibited liver cancer cell proliferation with high TRIM71 levels. Conclusions: We demonstrated the oncofetal status in liver cancer and highlighted the crucial role of TRIM71 and provided potential therapeutic strategies and liver cancer-specific biomarker for liver cancer patients.

Post-Transcriptional Regulator RBM47 Stabilizes FBXO2 mRNA to Advance Osteoarthritis Development: WGCNA Analysis and Experimental Validation

Osteoarthritis (OA) is a common chronic joint degenerative disease and a major cause of disability in the elderly. However, the current intervention strategies cannot effectively improve OA, and the pathogenesis of OA remains elusive. The present study identified RNA binding motif protein 47 (RBM47) as an upstream modulator of key dysregulation gene co-expression module based on weighted gene co-expression network analysis (WGCNA) analysis and least absolute shrinkage and selection operator (Lasso) modeling. Subsequently, data from real-time quantitative PCR and western blot analysis revealed that RBM47 was upregulated in OA models in vivo and in vitro compared with normal controls. Functional analysis results from the MTT assay, flow cytometry, evaluation of LDH activities and inflammatory mediators, and western blot analysis of extracellular matrix (ECM) proteins, showed that RBM47 knockdown significantly alleviated inflammation, apoptosis, and ECM degradation in interleukin 1β (IL-1β)-treated chondrocytes. Mechanistically, RBM47 bound to F box only protein 2 (FBXO2) and stabilized FBXO2 messenger RNA (mRNA) to promote the phosphorylation of signal transducer and activator of transcription 3 (STAT3) in chondrocytes. Results from the recovery assay showed that the re-activation of STAT3 signaling by overexpressing FBXO2 or STAT3 counteracted the alleviating effect of RBM47 downregulation on IL-1β-induced inflammation, apoptosis, and ECM degradation. Altogether, our findings illustrate that RBM47 stabilizes FBXO2 mRNA to advance OA development by activating STAT3 signaling, which enhances our understanding of the molecular regulatory mechanisms underlying the development of OA.

YTHDF3 phase separation regulates HSPA13-dependent clear cell renal cell carcinoma development and immune evasion

Insufficient understanding about the immune evasion mechanism leads to the inability in predicting current immunotherapy effects in clear cell renal cell carcinoma (ccRCC) and sensitizing ccRCC to immunotherapy. RNA binding proteins (RBPs) can promote tumor progression and immune evasion. However, research on RBPs, particularly m6A reader YTHDF3, in ccRCC development and immune evasion is limited. In this study, we found that YTHDF3 level was downregulated in ccRCC and was an independent prognostic biomarker for ccRCC. Decreased YTHDF3 expression was correlated with the malignancy, immune evasion, and poor response to anti-programmed death ligand 1 (PD-L1)/CTLA-4 in ccRCC. YTHDF3 overexpression restrained ccRCC cell malignancy, PD-L1 expression, CD8+ T cell infiltration and activities in vivo, indicating its inhibitory role in ccRCC development and immune evasion. Mechanistically, YTHDF3 WT was found to have phase separation characteristics and suppress ccRCC malignancy and immune evasion. Whereas YTHDF3 mutant, which disrupted phase separation, abolished its function. YTHDF3 enhanced the degradation of its target mRNA HSPA13 by phase separation and recruiting DDX6, resulting in the downregulation of the downstream immune checkpoint PD-L1. HSPA13 overexpression restored ccRCC malignancy and immune evasion suppressed by YTHDF3 overexpression. In all, our results identify a new model of YTHDF3 in regulating ccRCC progression and immune evasion through phase separation.

Genomic analysis uncovers that cold-inducible RNA binding protein is associated with estrogen receptor in breast cancer

BACKGROUND

RNA-binding proteins (RBPs) perform various biological functions in humans and are associated with several diseases, including cancer. Therefore, RBPs have emerged as novel therapeutic targets. Although recent investigations have shown that RBPs have crucial functions in breast cancer (BC), detailed research is underway to determine the RBPs that are closely related to cancers.

OBJECTIVE

To provide an insight into estrogen receptor (ER) regulation by cold-inducible RNA binding protein (CIRBP) as a novel therapeutic target.

RESULTS

By analyzing the genomic data, we identified a potential RBP in BC. We found that CIRBP is highly correlated with ER function and influences clinical outcomes, such as patient survival and endocrine therapy responsiveness. In addition, CIRBP influences the proliferation of BC cells by directly binding to ER-RNA.

CONCLUSION

Our results suggest that CIRBP is a novel upstream regulator of ER and that the interplay between CIRBP and ER may be associated with the clinical relevance of BC.

The comprehensive roles of lncRNA FAM99A/FAM99B in hepatocellular carcinoma: Expressions, regulatory mechanisms and functional pathway analysis

AIMS

The incidence and mortality of liver hepatocellular carcinoma (LIHC) were increasing year by year. The aim of this study was to investigate the comprehensive roles of lncRNA FAM99A and FAM99B in LIHC.

MAIN METHODS

According to the data of TCGA and GTEx, the expression levels of FAM99A and FAM99B in LIHC were evaluated, and the overall survival (OS), disease-free survival (DFS), immune cell infiltration and tumor stage were analyzed. The subcellular localization of FAM99A and FAM99B in various cancer cell lines was predicted by lncATLAS database. In addition, we also used ENCORI, KEGG, LinkedOmics, Metascape and other databases. It was verified by in vivo and in vitro experiments.

KEY FINDINGS

Compared with adjacent normal tissues, FAM99A and FAM99B were down-regulated in LIHC tissues, and significantly correlated with immune cell infiltration. With the progression of tumor stage and grade, the expression of FAM99A and FAM99B showed a decreasing trend, and the prognosis of patients were also poor. In addition, the biological functions, signaling pathways and protein interactions of FAM99A and FAM99B in LIHC were enriched to study the potential molecular mechanisms. The overlapping RNA binding proteins (RBP) of FAM99A and FAM99B mainly included CSTF2T, BCCIP, RBFOX2 and SF3B4. Finally, experiments showed that overexpression of FAM99A attenuated the proliferation, invasion, colony formation and tumor growth of LIHC cells.

SIGNIFICANCE

Taken together, the above studies demonstrated that FAM99A and FAM99B had an inhibitory effect on the progression of LIHC, which might be promising diagnostic biomarkers and therapeutic targets for LIHC patients.

O-GlcNAcylated RALY Contributes to Hepatocellular Carcinoma Cells Proliferation by Regulating USP22 mRNA Nuclear Export

Hepatocellular carcinoma (HCC) is one of the most prevalent and deadly tumors; however, its pathogenic mechanism remains largely elusive. In-depth researches are needed to reveal the expression regulatory mechanisms and functions of the RNA-binding protein RALY in HCC. Here, we identify RALY as a highly expressed oncogenic factor that affects HCC cells proliferation both in vitro and in vivo. O-GlcNAcylation of RALY at Ser176 enhances its stability by protecting RALY from TRIM27-mediated ubiquitination, thus maintaining hyper-expression of the RALY protein. Mechanistically, RALY interacts with USP22 messenger RNA, as revealed by RNA immunoprecipitation, to increase their cytoplasmic localization and protein expression, thereby promoting the proliferation of HCC cells. Furthermore, we develop a novel RALY protein degrader based on peptide proteolysis-targeting chimeras, named RALY-PROTAC, which we chemically synthesize by linking a RALY-targeting peptide with the E3 ubiquitin ligase recruitment ligand pomalidomide. In conclusion, our findings demonstrate a novel mechanism by which O-GlcNAcylation/RALY/USP22 mRNA axis aggravates HCC cells proliferation. RALY-PROTACs as degraders of the RALY protein exhibit potential as therapeutic drugs for RALY-overexpressing HCC.

The oncogenic role and regulatory mechanism of ACAA2 in human ovarian cancer

Acetyl-CoAacyltransferase2 (ACAA2) is a key enzyme in the fatty acid oxidation pathway that catalyzes the final step of mitochondrial β oxidation, which plays an important role in fatty acid metabolism. The expression of ACAA2 is closely related to the occurrence and malignant progression of tumors. However, the function of ACAA2 in ovarian cancer is unclear. The expression level and prognostic value of ACAA2 were analyzed by databases. Gain and loss of function were carried out to explore the function of ACAA2 in ovarian cancer. RNA-seq and bioinformatics methods were applied to illustrate the regulatory mechanism of ACAA2. ACAA2 overexpression promoted the growth, proliferation, migration, and invasion of ovarian cancer, and ACAA2 knockdown inhibited the malignant progression of ovarian cancer as well as the ability of subcutaneous tumor formation in nude mice. At the same time, we found that OGT can induce glycosylation modification of ACAA2 and regulate the karyoplasmic distribution of ACAA2. OGT plays a vital role in ovarian cancer as a function of oncogenes. In addition, through RNA-seq sequencing, we found that ACAA2 regulates the expression of DIXDC1. ACAA2 regulated the malignant progression of ovarian cancer through the WNT/β-Catenin signaling pathway probably. ACAA2 is an oncogene in ovarian cancer and has the potential to be a target for ovarian cancer therapy.

KDM2B is required for ribosome biogenesis and its depletion unequally affects mRNA translation

KDM2B is a JmjC domain lysine demethylase, which promotes cell immortalization, stem cell self-renewal and tumorigenesis. Here we employed a multi-omics strategy to address its role in ribosome biogenesis and mRNA translation. These processes are required to sustain cell proliferation, an important cancer hallmark. Contrary to earlier observations, KDM2B promotes ribosome biogenesis by stimulating the transcription of genes encoding ribosome biogenesis factors and ribosomal proteins, particularly those involved in the biogenesis of the 40S ribosomal subunits. Knockdown of KDM2B impaired the assembly of the small and large subunit processomes, as evidenced by specific defects in pre-ribosomal RNA processing. The final outcome was a decrease in the rate of ribosome assembly and in the abundance of ribosomes, and inhibition of mRNA translation. The inhibition of translation was distributed unequally among mRNAs with different features, suggesting that mRNA-embedded properties influence how mRNAs interpret ribosome abundance. This study identified a novel mechanism contributing to the regulation of translation and provided evidence for a rich biology elicited by a pathway that depends on KDM2B, and perhaps other regulators of translation.

CircRNAs: Pivotal modulators of TGF-β signalling in cancer pathogenesis

The intricate molecular landscape of cancer pathogenesis continues to captivate researchers worldwide, with Circular RNAs (circRNAs) emerging as pivotal players in the dynamic regulation of biological functions. The study investigates the elusive link between circRNAs and the Transforming Growth Factor-β (TGF-β) signalling pathway, exploring their collective influence on cancer progression and metastasis. Our comprehensive investigation begins by profiling circRNA expression patterns in diverse cancer types, revealing a repertoire of circRNAs intricately linked to the TGF-β pathway. Through integrated bioinformatics analyses and functional experiments, we elucidate the specific circRNA-mRNA interactions that modulate TGF-β signalling, unveiling the regulatory controls governing this crucial pathway. Furthermore, we provide compelling evidence of the impact of circRNA-mediated TGF-β modulation on key cellular processes, including epithelial-mesenchymal transition (EMT), migration, and cell proliferation. In addition to their mechanistic roles, circRNAs have shown promise as diagnostic and prognostic biomarkers, as well as potential molecular targets for cancer therapy. Their ability to modulate critical pathways, such as the TGF-β signalling axis, underscores their significance in cancer biology and clinical applications. The intricate interplay between circRNAs and TGF-β is dissected, uncovering novel regulatory circuits that contribute to the complexity of cancer biology. This review unravels a previously unexplored dimension of carcinogenesis, emphasizing the crucial role of circRNAs in shaping the TGF-β signalling landscape.

LARP4B promotes hepatocellular carcinoma progression and impairs sorafenib efficacy by activating SPINK1-mediated EGFR pathway

La-related proteins (LARPs) regulate gene expression by binding to RNAs and exhibit critical effects on disease progression, including tumors. However, the role of LARP4B and its underlying mechanisms in the progression of hepatocellular carcinoma (HCC) remain largely unclear. In this study, we found that LARP4B expression is upregulated and correlates with poor prognosis in patients with HCC. Gain- and loss-of-function assays showed that LARP4B promotes stemness, proliferation, metastasis, and angiogenesis in vitro and in vivo. Furthermore, LARP4B inhibition enhances the antitumor effects of sorafenib and blocks the metastasis-enhancing effects of low sorafenib concentrations in HCC. Mechanistically, LARP4B expression is upregulated by METTL3-mediated N6-methyladenosine (m6A)-IGF2BP3-dependent modification in HCC. RNA- and RNA immunoprecipitation (RIP)- sequencing uncovered that LARP4B upregulates SPINK1 by binding to SPINK1 mRNA via the La motif and maintaining mRNA stability. LARP4B activates the SPINK1-mediated EGFR signaling pathway, which supports stemness, progression and sorafenib resistance in HCC. Additionally, a positive feedback loop with the LARP4B/SPINK1/p-AKT/C/EBP-β axis is responsible for the sorafenib-therapeutic benefit of LARP4B depletion. Overall, this study demonstrated that LARP4B facilitates HCC progression, and LARP4B inhibition provides benefits to sorafenib treatment in HCC, suggesting that LARP4B might be a potential therapeutic target for HCC.

Loss of RNA-binding protein CELF2 promotes acute leukemia development via FAT10-mTORC1

RNA-binding proteins (RBPs) are critical regulators for RNA transcription and translation. As a key member of RBPs, ELAV-like family protein 2 (CELF2) has been shown to regulate RNA splicing and embryonic hematopoietic development and was frequently seen dysregulated in acute myeloid leukemia (AML). However, the functional role(s) of CELF2 in hematopoiesis and leukemogenesis has not been fully elucidated. In the current study, we showed that Celf2 deficiency in hematopoietic system led to enhanced HSCs self-renewal and differentiation toward myeloid cells in mice. Loss of Celf2 accelerated myeloid cell transformation and AML development in MLL-AF9-induced AML murine models. Gene expression profiling integrated with RNA immunoprecipitation sequencing (RIP-Seq), together with biochemical experiments revealed that CELF2 deficiency stabilizes FAT10 mRNA, promotes FAT10 translation, thereby increases AKT phosphorylation and mTORC1 signaling pathway activation. Notably, combination therapy with a mTORC1 inhibitor (Rapamycin) and a MA9/DOTL1 inhibitor (EPZ-5676) reduced the leukemia burden in MLL-AF9 mice lacking Celf2 in vivo. Our study elucidated a novel mechanism by which the CELF2/FAT10-AKT/mTORC1 axis regulates the proliferation of normal blood cells and the development of AML, thus providing potential therapeutic targets for myeloid leukemia suppression.

Targeting the "tumor microenvironment": RNA-binding proteins in the spotlight in colorectal cancer therapy

Colorectal cancer (CRC) is the third most common cancer and has the second highest mortality rate among cancers. The development of CRC involves both genetic and epigenetic abnormalities, and recent research has focused on exploring the ex-transcriptome, particularly post-transcriptional modifications. RNA-binding proteins (RBPs) are emerging epigenetic regulators that play crucial roles in post-transcriptional events. Dysregulation of RBPs can result in aberrant expression of downstream target genes, thereby affecting the progression of colorectal tumors and the prognosis of patients. Recent studies have shown that RBPs can influence CRC pathogenesis and progression by regulating various components of the tumor microenvironment (TME). Although previous research on RBPs has primarily focused on their direct regulation of colorectal tumor development, their involvement in the remodeling of the TME has not been systematically reported. This review aims to highlight the significant role of RBPs in the intricate interactions within the CRC tumor microenvironment, including tumor immune microenvironment, inflammatory microenvironment, extracellular matrix, tumor vasculature, and CRC cancer stem cells. We also highlight several compounds under investigation for RBP-TME-based treatment of CRC, including small molecule inhibitors such as antisense oligonucleotides (ASOs), siRNAs, agonists, gene manipulation, and tumor vaccines. The insights gained from this review may lead to the development of RBP-based targeted novel therapeutic strategies aimed at modulating the TME, potentially inhibiting the progression and metastasis of CRC.

BST2 promotes gastric cancer metastasis under the regulation of HOXD9 and PABPC1

Gastric cancer (GC) constitutes substantial cancer mortality worldwide. Several cancer types aberrantly express bone marrow stromal cell antigen 2 (BST2), yet its functional and underlying mechanisms in GC progression remain unknown. In our study, RNA sequencing data revealed that BST2 was transcriptionally activated by homeobox D9 (HOXD9). BST2 was significantly upregulated in GC tissues and promoted epithelial-mesenchymal transition and metastasis of GC. BST2 knockdown reversed HOXD9's oncogenic effect on GC metastasis. Moreover, BST2 messenger RNA stability could be enhanced by poly(A) binding protein cytoplasmic 1 (PABPC1) through the interaction between BST2 3'-UTR and PABPC1 in GC cells. PABPC1 promoted GC metastasis, which BST2 silencing attenuated in vitro and in vivo. In addition, positive correlations among HOXD9, BST2, and PABPC1 were established in clinical samples. Taken together, increased expression of BST2 induced by HOXD9 synergizing with PABPC1 promoted GC cell migration and invasion capacity.

Curriculum vitae of CUG binding protein 1 (CELF1) in homeostasis and diseases: a systematic review

RNA-binding proteins (RBPs) are kinds of proteins with either singular or multiple RNA-binding domains (RBDs), and they can assembly into ribonucleic acid-protein complexes, which mediate transportation, editing, splicing, stabilization, translational efficiency, or epigenetic modifications of their binding RNA partners, and thereby modulate various physiological and pathological processes. CUG-BP, Elav-like family 1 (CELF1) is a member of the CELF family of RBPs with high affinity to the GU-rich elements in mRNA, and thus exerting control over critical processes including mRNA splicing, translation, and decay. Mounting studies support that CELF1 is correlated with occurrence, genesis and development and represents a potential therapeutical target for these malignant diseases. Herein, we present the structure and function of CELF1, outline its role and regulatory mechanisms in varieties of homeostasis and diseases, summarize the identified CELF1 regulators and their structure-activity relationships, and prospect the current challenges and their solutions during studies on CELF1 functions and corresponding drug discovery, which will facilitate the establishment of a targeted regulatory network for CELF1 in diseases and advance CELF1 as a potential drug target for disease therapy.

RNA-binding proteins that preferentially interact with 8-oxoG-modified RNAs: our current understanding

Cells encounter a variety of stresses throughout their lifetimes. Oxidative stress can occur via a myriad of factors, including exposure to chemical toxins or UV light. Importantly, these stressors induce chemical changes (e.g. chemical modifications) to biomolecules, such as RNA. Commonly, guanine is oxidized to form 8-oxo-7,8-hydroxyguanine (8-oxoG) and this modification can disrupt a plethora of cellular processes including messenger RNA translation and stability. Polynucleotide phosphorylase (PNPase), heterogeneous nuclear ribonucleoprotein D (HNRPD/Auf1), poly(C)-binding protein (PCBP1/HNRNP E1), and Y-box binding protein 1 (YB-1) have been identified as four RNA-binding proteins that preferentially bind 8-oxoG-modified RNA over unmodified RNA. All four proteins are native to humans and PNPase is additionally found in bacteria. Additionally, under oxidative stress, cell survival declines in mutants that lack PNPase, Auf1, or PCBP1, suggesting they are critical to the oxidative stress response. This mini-review captures the current understanding of the PNPase, HNRPD/Auf1, PCBP1, and YB-1 proteins and the mechanism that has been outlined so far by which they recognize and interact with 8-oxoG-modified RNAs.

Phospholysine phosphohistidine inorganic pyrophosphate phosphatase suppresses insulin-like growth factor 1 receptor expression to inhibit cell adhesion and proliferation in gastric cancer

Phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) has recently emerged as a novel tumor suppressor. Researchers have observed that LHPP plays a crucial role in inhibiting proliferation, growth, migration, invasion, and cell metabolism across various cancers. Nevertheless, the specific functions and underlying mechanisms of LHPP as a tumor suppressor in gastric cancer (GC) require further exploration. The expression of LHPP was assessed in human GC specimens and cell lines. Various assays were employed to evaluate the impact of LHPP on GC cells. RNA sequencing and Gene Set Enrichment Analysis were conducted to unravel the mechanism through which LHPP regulates GC cell behavior. Additionally, xenograft nude mouse models were utilized to investigate the in vivo effects of LHPP. The findings indicate that LHPP, functioning as a tumor suppressor, is downregulated in both GC tissues and cells. LHPP emerges as an independent risk factor for GC patients, and its expression level exhibits a positive correlation with patient prognosis. LHPP exerts inhibitory effects on the adhesion and proliferation of GC cells by suppressing the expression of insulin-like growth factor 1 receptor (IGF1R) and modulating downstream signaling pathways. Consequently, LHPP holds potential as a biomarker for targeted therapy involving IGF1R inhibition in GC patients.

Cold-Inducible RNA Binding Protein Impedes Breast Tumor Growth in the PyMT Murine Model for Breast Cancer

RNA binding proteins (RBPs) post-transcriptionally regulate gene expression by associating with regulatory sequences in the untranslated regions of mRNAs. Cold-inducible RBP (CIRP) is a stress-induced RBP that was recently shown to modulate inflammation in response to cellular stress, where it increases or decreases pro-tumorigenic (proinflammatory) cytokines in different contexts. CIRP expression is altered in several cancers, including breast cancer, but the effects of CIRP on inflammation in breast cancer is not known. Here, we investigate if CIRP alters growth and the inflammatory profile of breast tumors. Transgenic mice overexpressing CIRP in the mammary epithelium were crossed with the PyMT mouse model of breast cancer, and the effects on both early and late tumorigenesis and inflammation were assessed. The effects of CIRP knockdown were also assessed in Py2T cell grafts. Overexpression of CIRP led to decreased tumorigenesis in the PyMT mouse model. Conversely, the knockdown of CIRP in Py2T cell grafts led to increased tumor growth. Luminex cytokine assays assessed the effects on the inflammatory environment. CIRP/PyMT mammary glands/mammary tumors and serum had decreased cytokines that promote inflammation, angiogenesis, and metastasis compared to PyMT mammary glands and serum, documenting a shift towards an environment less supportive of tumorigenesis. CIRP overexpression also decreased CD4+ helper T cells and increased CD8+ cytotoxic T cells in mammary tumors. Overall, these data support a role for CIRP as a potent antitumor molecule that suppresses both local and systemic pro-tumorigenic inflammation.

HuR (ELAVL1) Stabilizes SOX9 mRNA and Promotes Migration and Invasion in Breast Cancer Cells

RNA-binding proteins play diverse roles in cancer, influencing various facets of the disease, including proliferation, apoptosis, angiogenesis, senescence, invasion, epithelial-mesenchymal transition (EMT), and metastasis. HuR, a known RBP, is recognized for stabilizing mRNAs containing AU-rich elements (AREs), although its complete repertoire of mRNA targets remains undefined. Through a bioinformatics analysis of the gene expression profile of the Hs578T basal-like triple-negative breast cancer cell line with silenced HuR, we have identified SOX9 as a potential HuR-regulated target. SOX9 is a transcription factor involved in promoting EMT, metastasis, survival, and the maintenance of cancer stem cells (CSCs) in triple-negative breast cancer. Ribonucleoprotein immunoprecipitation assays confirm a direct interaction between HuR and SOX9 mRNA. The half-life of SOX9 mRNA and the levels of SOX9 protein decreased in cells lacking HuR. Cells silenced for HuR exhibit reduced migration and invasion compared to control cells, a phenotype similar to that described for SOX9-silenced cells.

The PIN1-YTHDF1 axis promotes breast tumorigenesis via the m6A-dependent stabilization of AURKA mRNA

The post-transcriptional processing of N6-methyladenosine (m6A)-modified mRNA by YTH domain-containing family protein 1 (YTHDF1) plays a crucial role in the regulation of gene expression. Although YTHDF1 expression is frequently upregulated in breast cancer, the regulatory mechanisms for this remain unclear. In this study, we examined the role of peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1) in regulating YTHDF1 stability in breast cancer cells. The WW domain of PIN1 interacted with YTHDF1 in a phosphorylation-dependent manner. Additionally, PIN1 overexpression increased YTHDF1 stability by preventing ubiquitin-dependent proteasomal degradation. Furthermore, using the MS2-tagged RNA pull-down assay, we identified Aurora kinase A (AURKA) mRNA as a bona fide substrate of YTHDF1. PIN1-mediated YTHDF1 stabilization increased the stability of AURKA mRNA in an m6A-dependent manner. Furthermore, YTHDF1 knockout reduced AURKA protein expression levels, resulting in anticancer effects in breast cancer cells, including decreased cell proliferation, cell cycle arrest at the G0/G1 phase, apoptotic cell death, and decreased spheroid formation. The anticancer effects induced by YTHDF1 knockout were reversed by AURKA overexpression. Similarly, the knockout of PIN1 produced comparable anticancer effects to those observed in YTHDF1-knockout cells, and these effects were reversed upon overexpression of YTHDF1. In conclusion, the findings of our study suggest that increased YTHDF1 stability induced by PIN1 promotes breast tumorigenesis via the stabilization of AURKA mRNA. Targeting the PIN1/YTHDF1 axis may represent a novel therapeutic strategy for breast cancer.

Downregulated RBM5 Enhances CARM1 Expression and Activates the PRKACA/GSK3β Signaling Pathway through Alternative Splicing-Coupled Nonsense-Mediated Decay

Downregulated RNA-binding motif protein 5 (RBM5) promotes the development and progression of various tumors, including bladder cancer (BC). Alternative splicing (AS) plays a crucial role in the progression of cancer by producing protein isomers with different functions or by promoting nonsense-mediated mRNA decay (NMD). However, whether RBM5 modulates the progression of BC through AS-NMD remains unexplored. In this study, we revealed that the downregulation of RBM5 expression promoted the expression of coactivator-associated arginine methyltransferase 1 (CARM1) in BC cells and tissues. Increased expression of CARM1 facilitated the activation of the Wnt/β-catenin axis and cell proliferation, which then contributed to the poor prognosis of patients with BC. Interestingly, RBM5 bound directly to CARM1 mRNA and participated in AS-NMD, downregulating the expression of CARM1. In addition, we revealed that protein kinase catalytic subunit alpha (PRKACA) functioned as a phosphorylated kinase of GSK3β, was regulated by CARM1 at the transcription level, and promoted the growth and progression of BC cells. Furthermore, in this study, we demonstrated a regulatory mechanism of Wnt/β-catenin activation through the RBM5/CARM1/PRKACA axis and identified a novel potential target for treating BC.

Profile analysis of N4-acetylcytidine (ac4C) on mRNA of human lung adenocarcinoma and paired adjacent non-tumor tissues

BACKGROUND

RNA modification, a major component of post-transcriptional modification, plays an essential role in tumor initiation and progression. N4-acetylcytidine (ac4C) present in different species as a highly conserved RNA modification. ac4C on mRNA increases the stability of mRNA and the efficiency of protein translation. However, the mRNA profiling of ac4C in lung adenocarcinoma (LUAD) is unknown.

METHODS

NAT10 expression was tested using immunohistochemistry in tissue microarray (TMA). The ac4C peaks on mRNA were identified through acetylated RNA immunoprecipitation sequencing in both human LUAD tissues and adjacent non-tumor tissues, and differences of acetylation and mRNA between the two groups were analyzed. Furthermore, the function of AC4C-specific acetylated transcripts was analyzed bioinformatically. And a ac-RIP-PCR was used to verify the ac4C acetylation sites of TFAP2A.

RESULTS

The expression of acetylated key enzyme NAT10 was obviously increased in LUAD group. Then we found noticeable differences in ac4C mRNA modification between LUAD and adjacent non-tumor tissues. In addition, bioinformatics analysis showed that the distinctive distribution pattern of mRNA ac4C in LUAD affects a variety of cellular functions, such as protein sumoylation and transmembrane transporter activity. Importantly, we verified the ac4C level of TFAP2A was up-regulated in LUAD.

CONCLUSIONS

Our study revealed that the degree of ac4C in mRNA in LUAD was significantly higher than in adjacent tissues and was concentrated mainly in the coding sequences with a implications in a wide range of cellular functions. The ac4C may become a new molecular marker and treatment target for lung cancer.

Hypoxia-induced circ-CDYL-EEF1A2 transcriptional complex drives lung metastasis of cancer stem cells from hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is often associated with poor outcomes due to lung metastasis. ICAM-1+ circulating tumor cells, termed circulating cancer stem cells (CCSCs), possess stem cell-like characteristics. However, it is still unexplored how their presence indicates lung metastasis tendency, and particularly, what mechanism drives their lung metastasis. Here, we demonstrated that a preoperative CCSC count in 5 mL of blood (CCSC5) of >3 was a risk factor for lung metastasis in clinical HCC patients. The CSCs overexpressed with circ-CDYL entered the bloodstream and developed lung metastases in mice. Mechanistically, circ-CDYL promoted COL14A1 expression and thus ERK signaling to facilitate epithelial-mesenchymal transition. Furthermore, we uncovered that an RNA-binding protein, EEF1A2, acted as a novel transcriptional (co-) factor to cooperate with circ-CDYL and initiate COL14A1 transcription. A high circ-CDYL level is caused by HIF-1⍺-mediated transcriptional upregulation of its parental gene CDYL and splicing factor EIF4A3 under a hypoxia microenvironment. Hence, the hypoxia microenvironment enables the high-tendency lung metastasis of ICAM-1+ CCSCs through the HIF-1⍺/circ-CDYL-EEF1A2/COL14A1 axis, potentially allowing clinicians to preoperatively detect ICAM-1+ CCSCs as a real-time biomarker for precisely deciding HCC treatment strategies.

Fates and functions of RNA-binding proteins under stress

Exposure to stress activates a well-orchestrated set of changes in gene expression programs that allow the cell to cope with and adapt to the stress, or undergo programmed cell death. RNA-protein interactions, mediating all aspects of post-transcriptional regulation of gene expression, play crucial roles in cellular stress responses. RNA-binding proteins (RBPs), which interact with sequence/structural elements in RNAs to control the steps of RNA metabolism, have therefore emerged as central regulators of post-transcriptional responses to stress. Following exposure to a variety of stresses, the dynamic alterations in the RNA-protein interactome enable cells to respond to intracellular or extracellular perturbations by causing changes in mRNA splicing, polyadenylation, stability, translation, and localization. As RBPs play a central role in determining the cellular proteome both qualitatively and quantitatively, it has become increasingly evident that their abundance, availability, and functions are also highly regulated in response to stress. Exposure to stress initiates a series of signaling cascades that converge on post-translational modifications (PTMs) of RBPs, resulting in changes in their subcellular localization, association with stress granules, extracellular export, proteasomal degradation, and RNA-binding activities. These alterations in the fate and function of RBPs directly impact their post-transcriptional regulatory roles in cells under stress. Adopting the ubiquitous RBP HuR as a prototype, three scenarios illustrating the changes in nuclear-cytoplasmic localization, RNA-binding activity, export and degradation of HuR in response to inflammation, genotoxic stress, and heat shock depict the complex and interlinked regulatory mechanisms that control the fate and functions of RBPs under stress. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.

Intra- and inter-molecular regulation by intrinsically-disordered regions governs PUF protein RNA binding

PUF proteins are characterized by globular RNA-binding domains. They also interact with partner proteins that modulate their RNA-binding activities. Caenorhabditis elegans PUF protein fem-3 binding factor-2 (FBF-2) partners with intrinsically disordered Lateral Signaling Target-1 (LST-1) to regulate target mRNAs in germline stem cells. Here, we report that an intrinsically disordered region (IDR) at the C-terminus of FBF-2 autoinhibits its RNA-binding affinity by increasing the off rate for RNA binding. Moreover, the FBF-2 C-terminal region interacts with its globular RNA-binding domain at the same site where LST-1 binds. This intramolecular interaction restrains an electronegative cluster of amino acid residues near the 5' end of the bound RNA to inhibit RNA binding. LST-1 binding in place of the FBF-2 C-terminus therefore releases autoinhibition and increases RNA-binding affinity. This regulatory mechanism, driven by IDRs, provides a biochemical and biophysical explanation for the interdependence of FBF-2 and LST-1 in germline stem cell self-renewal.

Ppm1d truncating mutations promote the development of genotoxic stress-induced AML

Hematopoietic stem cells (HSCs) ensure blood cell production during the life-time of an organism, and to do so they need to balance self-renewal, proliferation, differentiation, and migration in a steady state as well as in response to stress or injury. Importantly, aberrant proliferation of HSCs leads to hematological malignancies, and thus, tight regulation by various tumor suppressor pathways, including p53, is essential. Protein phosphatase magnesium-dependent 1 delta (PPM1D) is a negative regulator of p53 and promotes cell survival upon induction of genotoxic stress. Truncating mutations in the last exon of PPM1D lead to the production of a stable, enzymatically active protein and are commonly associated with clonal hematopoiesis. Using a transgenic mouse model, we demonstrate that truncated PPM1D reduces self-renewal of HSCs in basal conditions but promotes the development of aggressive AML after exposure to ionizing radiation. Inhibition of PPM1D suppressed the colony growth of leukemic stem and progenitor cells carrying the truncated PPM1D, and remarkably, it provided protection against irradiation-induced cell growth. Altogether, we demonstrate that truncated PPM1D affects HSC maintenance, disrupts normal hematopoiesis, and that its inhibition could be beneficial in the context of therapy-induced AML.

The RNA methyltransferase METTL16 enhances cholangiocarcinoma growth through PRDM15-mediated FGFR4 expression

BACKGROUND

RNA N6-Methyladenosine (m6A) modification is implicated in the progression of human cancers including cholangiocarcinoma (CCA). METTL16 is recently identified as a new RNA methyltransferase responsible for m6A modification, although the role of METTL16 in CCA has not yet been examined. The current study aims to investigate the effect and mechanism of the RNA methyltransferase METTL16 in CCA.

METHODS

The expression of METTL16 in CCA was examined by analyzing publicly available datasets or by IHC staining on tumor samples. siRNA or CRISPR/Cas9-mediated loss of function studies were performed in vitro and in vivo to investigate the oncogenic role of METTL16 in CCA. MeRIP-Seq was carried out to identify the downstream target of METTL16. ChIP-qPCR, immunoprecipitation, and immunoblots were used to explore the regulation mechanisms for METTL16 expression in CCA.

RESULTS

We observed that the expression of METTL16 was noticeably increased in human CCA tissues. Depletion of METTL16 significantly inhibited CCA cell proliferation and decreased tumor progression. PRDM15 was identified as a key target of METTL16 in CCA cells. Mechanistically, our data showed that METTL16 regulated PRDM15 protein expression via YTHDF1-dependent translation. Accordingly, we observed that restoration of PRDM15 expression could rescue the deficiency of CCA cell proliferation/colony formation induced by METTL16 depletion. Our subsequent analyses revealed that METTL16-PRDM15 signaling regulated the expression of FGFR4 in CCA cells. Specifically, we observed that PRDM15 protein was associated with the FGFR4 promoter to regulate its expression. Furthermore, we showed that the histone acetyltransferase p300 cooperated with the transcription factor YY1 to regulate METTL16 gene expression via histone H3 lysine 27 (H3K27) acetylation in CCA cells.

CONCLUSIONS

This study describes a novel METTL16-PRDM15-FGFR4 signaling axis which is crucial for CCA growth and may have important therapeutic implications. We showed that depletion of METTL16 significantly inhibited CCA cell proliferation and decreased tumor progression.

Role of the RNA-binding protein family in gynecologic cancers

Gynecological cancers pose a threat to women's health. Although early-stage gynecological cancers show good outcomes after standardized treatment, the prognosis of patients with advanced, met-astatic, and recurrent cancers is poor. RNA-binding proteins (RBPs) are important cellular proteins that interact with RNA through RNA-binding domains and participate extensively in post-transcriptional regulatory processes, such as mRNA alternative splicing, polyadenylation, intracellular localization and stability, and translation. Abnormal RBP expression affects the normal function of oncogenes and tumor suppressor genes in many malignancies, thus leading to the occurrence or progression of cancers. Similarly, RBPs play crucial roles in gynecological carcinogenesis. We summarize the role of RBPs in gynecological malignancies and explore their potential in the diagnosis and treatment of cancers. The findings summarized in this review may provide a guide for future research on the functions of RBPs.

Surmounting Cancer Drug Resistance: New Perspective on RNA-Binding Proteins

RNA-binding proteins (RBPs), being pivotal elements in both physiological and pathological processes, possess the ability to directly impact RNA, thereby exerting a profound influence on cellular life. Furthermore, the dysregulation of RBPs not only induces alterations in the expression levels of genes associated with cancer but also impairs the occurrence of post-transcriptional regulatory mechanisms. Consequently, these circumstances can give rise to aberrations in cellular processes, ultimately resulting in alterations within the proteome. An aberrant proteome can disrupt the equilibrium between oncogenes and tumor suppressor genes, promoting cancer progression. Given their significant role in modulating gene expression and post-transcriptional regulation, directing therapeutic interventions towards RBPs represents a viable strategy for combating drug resistance in cancer treatment. RBPs possess significant potential as diagnostic and prognostic markers for diverse cancer types. Gaining comprehensive insights into the structure and functionality of RBPs, along with delving deeper into the molecular mechanisms underlying RBPs in tumor drug resistance, can enhance cancer treatment strategies and augment the prognostic outcomes for individuals afflicted with cancer.

Functional Role of RBP in Osteosarcoma: Regulatory Mechanism and Clinical Therapy

Malignant bone neoplasms can be represented by osteosarcoma (OS), which accounts for 36% of all sarcomas. To reduce tumor malignancy, extensive efforts have been devoted to find an ideal target from numerous candidates, among which RNA-binding proteins (RBPs) have shown their unparalleled competitiveness. With the special structure of RNA-binding domains, RBPs have the potential to establish relationships with RNAs or small molecules and are considered regulators of different sections of RNA processes, including splicing, transport, translation, and degradation of RNAs. RBPs have considerable significant roles in various cancers, and experiments revealed that there was a strong association of RBPs with tumorigenesis and tumor cell progression. Regarding OS, RBPs are a new orientation, but achievements in hand are noteworthy. Higher or lower expression of RBPs was first found in tumor cells compared to normal tissue. By binding to different molecules, RBPs are capable of influencing tumor cell phenotypes through different signaling pathways or other axes, and researches on medical treatment have been largely inspired. Exploring the prognostic and therapeutic values of RBPs in OS is a hotspot where diverse avenues on regulating RBPs have achieved dramatical effects. In this review, we briefly summarize the contribution of RBPs and their binding molecules to OS oncogenicity and generally introduce distinctive RBPs as samples. Moreover, we focus on the attempts to differentiate RBP's opposite functions in predicting prognosis and collect possible strategies for treatment. Our review provides forwards insight into improving the understanding of OS and suggests RBPs as potential biomarkers for therapies.

New Functions of Intracellular LOXL2: Modulation of RNA-Binding Proteins

Lysyl oxidase-like 2 (LOXL2) was initially described as an extracellular enzyme involved in extracellular matrix remodeling. Nevertheless, numerous recent reports have implicated intracellular LOXL2 in a wide variety of processes that impact on gene transcription, development, differentiation, proliferation, migration, cell adhesion, and angiogenesis, suggesting multiple different functions for this protein. In addition, increasing knowledge about LOXL2 points to a role in several types of human cancer. Moreover, LOXL2 is able to induce the epithelial-to-mesenchymal transition (EMT) process-the first step in the metastatic cascade. To uncover the underlying mechanisms of the great variety of functions of intracellular LOXL2, we carried out an analysis of LOXL2's nuclear interactome. This study reveals the interaction of LOXL2 with numerous RNA-binding proteins (RBPs) involved in several aspects of RNA metabolism. Gene expression profile analysis of cells silenced for LOXL2, combined with in silico identification of RBPs' targets, points to six RBPs as candidates to be substrates of LOXL2's action, and that deserve a more mechanistic analysis in the future. The results presented here allow us to hypothesize novel LOXL2 functions that might help to comprehend its multifaceted role in the tumorigenic process.

YBX2 modulates mRNA stability via interaction with YTHDF2 in endometrial cancer cells

RNA-binding proteins (RBPs) fine-tune gene expression by modulating RNA stability, translation, and degradation. RBPs are involved in the development of endometrial cancer. In particular, Y-box binding protein 2 (YBX2), a germ cell-specific member of the YBX family, has been reported to maintain cancer stem cell-like phenotypes in endometrial cancer. However, the mechanism by which YBX2 modulates mRNA stability in endometrial cancer cells remains unknown. In this study, we examined the effects of the ectopic expression of YBX2 in endometrial adenocarcinoma-derived Ishikawa cells. We found that elevated levels of YBX2 delayed cell proliferation, without increasing cell apoptosis. Transcriptomic analysis revealed disturbances in gene expression caused by YBX2. Interestingly, heat shock protein family A (Hsp70) member 6 (HSPA6) levels were downregulated due to the reduced mRNA stability after YBX2 binding. YBX2 facilitated the formation of relatively stable cytoplasmic granules in tumor cells via its mRNA-binding domain. Moreover, N⁶-methyladenosine (m⁶A) reader proteins are recruited by YBX2 granules via the cold-shock domains. Notably, knockdown of YTH N⁶-methyladenosine RNA-binding protein F2 (YTHDF2), an m⁶A reader, ameliorated the reduction in HSPA6 mRNA levels induced by YBX2, indicating the synergistic effects of YBX2 and YTHDF2 on mRNA stability. Therefore, YBX2 regulates RNA stability by interacting with the m⁶A reader proteins.