KH-type splicing regulatory protein is involved in esophageal squamous cell carcinoma progression

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

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

KSRP improves pancreatic beta cell function and survival

Impaired insulin production and/or secretion by pancreatic beta cells can lead to high blood glucose levels and type 2 diabetes (T2D). Therefore, investigating new proteins involved in beta cell response to stress conditions could be useful in finding new targets for therapeutic approaches. KH-type splicing regulatory protein (KSRP) is a protein usually involved in gene expression due to its role in post-transcriptional regulation. Although there are studies describing the important role of KSRP in tissues closely related to glucose homeostasis, its effect on pancreatic beta cells has not been explored so far. Pancreatic islets from diet-induced obese mice (C57BL/6JUnib) were used to determine KSRP expression and we also performed in vitro experiments exposing INS-1E cells (pancreatic beta cell line) to different stressors (palmitate or cyclopiazonic acid-CPA) to induce cellular dysfunction. Here we show that KSRP expression is reduced in all the beta cell dysfunction models tested. In addition, when manipulated to knock down KSRP, beta cells exhibited increased death and impaired insulin secretion, whereas KSRP overexpression prevented cell death and increased insulin secretion. Taken together, our findings suggest that KSRP could be an important target to protect beta cells from impaired functioning and death.

K-Homology Type Splicing Regulatory Protein: Mechanism of Action in Cancer and Immune Disorders

K homology-type splicing regulatory protein (KSRP) is emerging as a key player in cancer biology, and immunology. As a single-strand nucleic acid binding protein it functions in both transcriptional and post-transcriptional regulation, while facilitating multiple stages of RNA metabolism to affect proliferation and control cell fate. However, it must interact with other proteins to determine the fate of its bound substrate. Here we provide an minireview of this important regulatory protein and describe its complex subcellular functions to affect RNA metabolism, stability, miRNA biogenesis and maturation, stress granule function, metastasis, and inflammatory processes.

The RNA-binding protein KSRP aggravates malignant progression of clear cell renal cell carcinoma through transcriptional inhibition and post-transcriptional destabilization of the NEDD4L ubiquitin ligase

BACKGROUND

KH-type splicing regulatory protein (KHSRP, also called KSRP), a versatile RNA-binding protein, plays a critical role in various physiological and pathological conditions through modulating gene expressions at multiple levels. However, the role of KSRP in clear cell renal cell carcinoma (ccRCC) remains poorly understood.

METHODS

KSRP expression was detected by a ccRCC tissue microarray and evaluated by an in silico analysis. Cell loss-of-function and gain-of-function, colony-formation, anoikis, and transwell assays, and an orthotopic bioluminescent xenograft model were conducted to determine the functional role of KRSP in ccRCC progression. Micro (mi)RNA and complementary (c)DNA microarrays were used to identify downstream targets of KSRP. Western blotting, quantitative real-time polymerase chain reaction, and promoter- and 3-untranslated region (3'UTR)-luciferase reporter assays were employed to validate the underlying mechanisms of KSRP which aggravate progression of ccRCC.

RESULTS

Our results showed that dysregulated high levels of KSRP were correlated with advanced clinical stages, larger tumor sizes, recurrence, and poor prognoses of ccRCC. Neural precursor cell-expressed developmentally downregulated 4 like (NEDD4L) was identified as a novel target of KSRP, which can reverse the protumorigenic and prometastatic characteristics as well as epithelial-mesenchymal transition (EMT) promotion by KSRP in vitro and in vivo. Molecular studies revealed that KSRP can decrease NEDD4L messenger (m)RNA stability via inducing mir-629-5p upregulation and directly targeting the AU-rich elements (AREs) of the 3'UTR. Moreover, KSRP was shown to transcriptionally suppress NEDD4L via inducing the transcriptional repressor, Wilm's tumor 1 (WT1). In the clinic, ccRCC samples revealed a positive correlation between KSRP and mesenchymal-related genes, and patients expressing high KSRP and low NEDD4L had the worst prognoses.

CONCLUSION

The current findings unveil novel mechanisms of KSRP which promote malignant progression of ccRCC through transcriptional inhibition and post-transcriptional destabilization of NEDD4L transcripts. Targeting KSRP and its pathways may be a novel pharmaceutical intervention for ccRCC.

RNA binding proteins (RBPs) and their role in DNA damage and radiation response in cancer

Traditionally majority of eukaryotic gene expression is influenced by transcriptional and post-transcriptional events. Alterations in the expression of proteins that act post-transcriptionally can affect cellular signaling and homeostasis. RNA binding proteins (RBPs) are a family of proteins that specifically bind to RNAs and are involved in post-transcriptional regulation of gene expression and important cellular processes such as cell differentiation and metabolism. Deregulation of RNA-RBP interactions and any changes in RBP expression or function can lead to various diseases including cancer. In cancer cells, RBPs play an important role in regulating the expression of tumor suppressors and oncoproteins involved in various cell-signaling pathways. Several RBPs such as HuR, AUF1, RBM38, LIN28, RBM24, tristetrapolin family and Musashi play critical roles in various types of cancers and their aberrant expression in cancer cells makes them an attractive therapeutic target for cancer treatment. In this review we provide an overview of i). RBPs involved in cancer progression and their mechanism of action ii). the role of RBPs, including HuR, in breast cancer progression and DNA damage response and iii). explore RBPs with emphasis on HuR as therapeutic target for breast cancer therapy.

The function and regulatory mechanism of RNA-binding proteins in breast cancer and their future clinical treatment prospects

Breast cancer is the most common female malignancy, but the mechanisms regulating gene expression leading to its development are complex. In recent years, as epigenetic research has intensified, RNA-binding proteins (RBPs) have been identified as a class of posttranscriptional regulators that can participate in regulating gene expression through the regulation of RNA stabilization and degradation, intracellular localization, alternative splicing and alternative polyadenylation, and translational control. RBPs play an important role in the development of normal mammary glands and breast cancer. Functional inactivation or abnormal expression of RBPs may be closely associated with breast cancer development. In this review, we focus on the function and regulatory mechanisms of RBPs in breast cancer, as well as the advantages and challenges of RBPs as potential diagnostic and therapeutic targets in breast cancer, and discuss the potential of RBPs in clinical treatment.

The Role of KH-Type Splicing Regulatory Protein (KSRP) for Immune Functions and Tumorigenesis

Post-transcriptional control of gene expression is one important mechanism that enables stringent and rapid modulation of cytokine, chemokines or growth factors expression, all relevant for immune or tumor cell function and communication. The RNA-binding protein KH-type splicing regulatory protein (KSRP) controls the mRNA stability of according genes by initiation of mRNA decay and inhibition of translation, and by enhancing the maturation of microRNAs. Therefore, KSRP plays a pivotal role in immune cell function and tumor progression. In this review, we summarize the current knowledge about KSRP with regard to the regulation of immunologically relevant targets, and the functional role of KSRP on immune responses and tumorigenesis. KSRP is involved in the control of myeloid hematopoiesis. Further, KSRP-mediated mRNA decay of pro-inflammatory factors is necessary to keep immune homeostasis. In case of infection, functional impairment of KSRP is important for the induction of robust immune responses. In this regard, KSRP seems to primarily dampen T helper cell 2 immune responses. In cancer, KSRP has often been associated with tumor growth and metastasis. In summary, aside of initiation of mRNA decay, the KSRP-mediated regulation of microRNA maturation seems to be especially important for its diverse biological functions, which warrants further in-depth examination.

Network analysis reveals dysregulated functional patterns in type II diabetic skin

Skin disorders are one of the most common complications of type II diabetes (T2DM). Long-term effects of high blood glucose leave individuals with T2DM more susceptible to cutaneous diseases, but its underlying molecular mechanisms are unclear. Network-based methods consider the complex interactions between genes which can complement the analysis of single genes in previous research. Here, we use network analysis and topological properties to systematically investigate dysregulated gene co-expression patterns in type II diabetic skin with skin samples from the Genotype-Tissue Expression database. Our final network consisted of 8812 genes from 73 subjects with T2DM and 147 non-T2DM subjects matched for age, sex, and race. Two gene modules significantly related to T2DM were functionally enriched in the pathway lipid metabolism, activated by PPARA and SREBF (SREBP). Transcription factors KLF10, KLF4, SP1, and microRNA-21 were predicted to be important regulators of gene expression in these modules. Intramodular analysis and betweenness centrality identified NCOA6 as the hub gene while KHSRP and SIN3B are key coordinators that influence molecular activities differently between T2DM and non-T2DM populations. We built a TF-miRNA-mRNA regulatory network to reveal the novel mechanism (miR-21-PPARA-NCOA6) of dysregulated keratinocyte proliferation, differentiation, and migration in diabetic skin, which may provide new insights into the susceptibility of skin disorders in T2DM patients. Hub genes and key coordinators may serve as therapeutic targets to improve diabetic skincare.

Identification of KHSRP-Regulated RNAs in Esophageal Cancer by Integrated Bioinformatics Analysis

Background: The objective of this study was to identify key molecules that included long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and mRNAs involved in esophageal cancer with KH-type splicing regulatory protein (KHSRP) knockdown. Materials and Methods: GSE99422 and GSE99423 from Gene Expression Omnibus database were extracted. After differentially expressed analysis of miRNAs, lncRNAs, and mRNAs, the lncRNAs-mRNAs interaction was obtained. Then the protein-protein interaction (PPI) network and module analyses were performed for differentially expressed mRNAs (DEmRNAs). Combined with miRWalk tool and DIANA-LncBase tool, regulating relationship between differentially expressed miRNAs (DEmiRNAs) and DEmRNAs/DElncRNAs were predicted. Finally, mRNA-miRNA-lncRNA regulatory network construction was established by Cytoscape software. Finally, the key genes were validated based on the Gene Expression Profiling Interactive Analysis (GEPIA) database. Results: Totally, 2,027 DEmiRNAs, 3,480 DElncRNAs, and 18,293 DEmRNAs were screened. The PPI network included 399 nodes and 1671 interaction pairs, and two function models (Cluster 1 and Cluster 2) were separately identified. The PLK1 was a hub in the Cluster 1, which mainly enriched in the function of nuclear division. Then the competing endogenous RNA (ceRNA) network was constructed with 20 miRNAs, 66 lncRNA, and 202 mRNA. Here, lncRNA RP11-159D12.2 might function as a ceRNA in regulating BIRC5 expression of esophagus cancer through competitively binding to hsa-miR-4430. BIRC5 was mainly enriched in the function of mitotic nuclear division. Besides, the expression of BIRC5 and PLK1 genes was upregulated in tumor tissues compared with normal controls. Also, the correlation analysis showed that the key genes (BIRC5 and PLK1) were validated to be positively correlated with KHSRP. Conclusions: PLK1, BIRC5, hsa-miR-4430, and lncRNA RP11-159D12.2 were likely to be associated with esophageal cancer development.

miR-301 regulates the SIRT1/SOX2 pathway via CPEB1 in the breast cancer progression

Breast cancer, the most common malignant tumor in women, has become a worldwide burden for family and society. MicroRNAs (miRNAs or miRs) are recognized as critical mediators of cancer-related processes, since they have the ability to coordinately suppress multiple target genes. In this study, we aim to find out specific miRNAs involved in the progression of breast cancer and explore the underlying molecular mechanism. Bioinformatics analysis suggested miR-301 as a differentially overexpressed miRNA in breast cancer, which was confirmed by expression determination. Functional assays were employed to explore the effect of miR-301 and its downstream effectors cytoplasmic polyadenylation element-binding protein 1 (CPEB1), SIRT1, and SOX2 on malignant phenotypes of breast cancer. The interaction among these factors was explained using luciferase and RNA immunoprecipitation (RIP) assays. In addition, the in vivo impact of miR-301 on breast cancer was assessed by cellular tumorigenicity in nude mice. We found that miR-301 overexpression restricted CPEB1 level and further promoted cell proliferation, metastasis, and cell cycle progression and impeded apoptosis. Moreover, CPEB1 regulated breast cancer development by mediating the SIRT1/SOX2 pathway. Further, miR-301 overexpression accelerated tumor formation in nude mice. Our results indicate that miR-301 overexpression accelerates the progression of breast cancer through the CPEB1/SIRT1/SOX2 axis.

RNA-Binding Proteins in Cancer: Functional and Therapeutic Perspectives

Simple Summary

RNA-binding proteins (RBPs) play central roles in regulating posttranscriptional expression of genes. Many of them are known to be deregulated in a wide variety of cancers. Dysregulated RBPs influence the expression levels of target RNAs related to cancer phenotypes, such as proliferation, apoptosis, angiogenesis, senescence, and EMT/invasion/metastasis. Thus, understanding the molecular functions of RBPs and their roles in cancer-related phenotypes can lead to improved therapeutic strategies.

Abstract

RNA-binding proteins (RBPs) crucially regulate gene expression through post-transcriptional regulation, such as by modulating microRNA (miRNA) processing and the alternative splicing, alternative polyadenylation, subcellular localization, stability, and translation of RNAs. More than 1500 RBPs have been identified to date, and many of them are known to be deregulated in cancer. Alterations in the expression and localization of RBPs can influence the expression levels of oncogenes, tumor-suppressor genes, and genome stability-related genes. RBP-mediated gene regulation can lead to diverse cancer-related cellular phenotypes, such as proliferation, apoptosis, angiogenesis, senescence, and epithelial-mesenchymal transition (EMT)/invasion/metastasis. This regulation can also be associated with cancer prognosis. Thus, RBPs can be potential targets for the development of therapeutics for the cancer treatment. In this review, we describe the molecular functions of RBPs, their roles in cancer-related cellular phenotypes, and various approaches that may be used to target RBPs for cancer treatment.

Claudin-6 is a single prognostic marker and functions as a tumor-promoting gene in a subgroup of intestinal type gastric cancer

BACKGROUND

We aimed to identify novel tumor-promoting drivers highly expressed in gastric cancer (GC) that contribute to worsened prognosis in affected patients.

METHODS

Genes whose expression was increased and correlated with worse prognosis in GC were screened using datasets from the Cancer Genome Atlas and Gene Expression Omnibus. We examined Claudin-6 (CLDN6) immunoreactivity in GC tissues and the effect of CLDN6 on cellular functions in GC cell lines. The mechanisms underlying GC-promoting function of CLDN6 were also investigated.

RESULTS

CLDN6 was identified as a gene overexpressed in GC tumors as compared with adjacent non-tumorous tissues and whose increased expression was positively correlated with worse overall survival of GC patients, particularly those with Lauren's intestinal type GC, in data from multiple publicly available datasets. Additionally, membranous CLDN6 immunoreactivity detected in intestinal type GC tumors was correlated with worse overall survival. In CLDN6-expressing GC cells, silencing of CLDN6 inhibited cell proliferation and migration/invasion abilities, possibly via suppressing transcription of YAP1 and its downstream transcriptional targets at least in part.

CONCLUSIONS

This study identified CLDN6 as a GC-promoting gene, suggesting that CLDN6 to be a possible single prognostic marker and promising therapeutic target for a subset of GC patients.

KH-Type Splicing Regulatory Protein Controls Colorectal Cancer Cell Growth and Modulates the Tumor Microenvironment

KH-type splicing regulatory protein (KHSRP) is a multifunctional nucleic acid binding protein implicated in key aspects of cancer cell biology: inflammation and cell-fate determination. However, the role KHSRP plays in colorectal cancer (CRC) tumorigenesis remains largely unknown. Using a combination of in silico analysis of large data sets, ex vivo analysis of protein expression in patients, and mechanistic studies using in vitro models of CRC, we investigated the oncogenic role of KHSRP. We demonstrated KHSRP expression in the epithelial and stromal compartments of both primary and metastatic tumors. Elevated expression was found in tumor versus matched normal tissue, and these findings were validated in larger independent cohorts in silico. KHSRP expression was a prognostic indicator of worse overall survival (hazard ratio, 3.74; 95% CI, 1.43-22.97; P = 0.0138). Mechanistic data in CRC cell line models supported a role of KHSRP in driving epithelial cell proliferation in both a primary and metastatic setting, through control of the G₁/S transition. In addition, KHSRP promoted a proangiogenic extracellular environment by regulating the secretion of oncogenic proteins involved in diverse cellular processes, such as migration and response to cellular stress. Our study provides novel mechanistic insight into the tumor-promoting effects of KHSRP in CRC.

Diverse roles of RNA-binding proteins in cancer traits and their implications in gastrointestinal cancers

Gene expression patterns in cancer cells are strongly influenced by posttranscriptional mechanisms. RNA-binding proteins (RBPs) play key roles in posttranscriptional gene regulation; they can interact with target mRNAs in a sequence- and structure-dependent manner, and determine cellular behavior by manipulating the processing of these mRNAs. Numerous RBPs are aberrantly deregulated in many human cancers and hence, affect the functioning of mRNAs that encode proteins, implicated in carcinogenesis. Here, we summarize the key roles of RBPs in posttranscriptional gene regulation, describe RBPs disrupted in cancer, and lastly focus on RBPs that are responsible for implementing cancer traits in the digestive tract. These evidences may reveal a potential link between changes in expression/function of RBPs and malignant transformation, and a framework for new insights and potential therapeutic applications. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.