Long non-coding RNA LINC00152 promotes cell proliferation, metastasis, and confers 5-FU resistance in colorectal cancer by inhibiting miR-139-5p

Unraveling the role of long non-coding RNAs in therapeutic resistance in acute myeloid leukemia: New prospects & challenges

Acute Myeloid Leukemia (AML) is a fatal hematological disease characterized by the unchecked proliferation of immature myeloid blasts in different tissues developed by various mutations in hematopoiesis. Despite intense chemotherapeutic regimens, patients often experience poor outcomes, leading to substandard remission rates. In recent years, long non-coding RNAs (lncRNAs) have increasingly become important prognostic and therapeutic hotspots, due to their contributions to dysregulating many functional epigenetic, transcriptional, and post-translational mechanisms leading to alterations in cell expressions, resulting in increased chemoresistance and reduced apoptosis in leukemic cells. Through this review, I highlight and discuss the latest advances in understanding the major mechanisms through which lncRNAs confer therapy resistance in AML. In addition, I also provide perspective on the current strategies to target lncRNA expressions. A better knowledge of the critical role that lncRNAs play in controlling treatment outcomes in AML will help improve existing medications and devise new ones.

Targeting LINC00152 activates cAMP/Ca2+/ferroptosis axis and overcomes tamoxifen resistance in ER+ breast cancer

Tamoxifen has been the mainstay therapy to treat early, locally advanced, and metastatic estrogen receptor-positive (ER + ) breast cancer, constituting around 75% of all cases. However, the emergence of resistance is common, necessitating the identification of novel therapeutic targets. Here, we demonstrated that long-noncoding RNA LINC00152 confers tamoxifen resistance by blocking tamoxifen-induced ferroptosis, an iron-mediated cell death. Mechanistically, inhibiting LINC00152 reduces the mRNA stability of phosphodiesterase 4D (PDE4D), leading to activation of the cAMP/PKA/CREB axis and increased expression of the TRPC1 Ca2+ channel. This causes cytosolic Ca2+ overload and generation of reactive oxygen species (ROS) that is, on the one hand, accompanied by downregulation of FTH1, a member of the iron sequestration unit, thus increasing intracellular Fe2+ levels; and on the other hand, inhibition of the peroxidase activity upon reduced GPX4 and xCT levels, in part by cAMP/CREB. These ultimately restore tamoxifen-dependent lipid peroxidation and ferroptotic cell death which are reversed upon chelating Ca2+ or overexpressing GPX4 or xCT. Overexpressing PDE4D reverses LINC00152 inhibition-mediated tamoxifen sensitization by de-activating the cAMP/Ca2+/ferroptosis axis. Importantly, high LINC00152 expression is significantly correlated with high PDE4D/low ferroptosis and worse survival in multiple cohorts of tamoxifen- or tamoxifen-containing endocrine therapy-treated ER+ breast cancer patients. Overall, we identified LINC00152 inhibition as a novel mechanism of tamoxifen sensitization via restoring tamoxifen-dependent ferroptosis upon destabilizing PDE4D, increasing cAMP and Ca2+ levels, thus leading to ROS generation and lipid peroxidation. Our findings reveal LINC00152 and its effectors as actionable therapeutic targets to improve clinical outcome in refractory ER+ breast cancer.

LINC00152: Potential driver oncogene in pan-cancer

Long noncoding RNAs (lncRNA) are a class of non-coding RNAs greater than 200 bp in length with limited peptide-coding function. The transcription of LINC00152 is derived from chromosome 2p11.2. Many studies prove that LINC00152 influences the progression of various tumors via promoting the tumor cells malignant phenotype, chemoresistance, and immune escape. LINC00152 is regulated by multiple transcription factors and DNA hypomethylation. In addition, LINC00152 participates in the regulation of complex molecular signaling networks through epigenetic regulation, protein interactions, and competitive endogenous RNA (ceRNA). Here, we provide a systematic review of the upstream regulatory factors of LINC00152 expression level in different types of tumors. In addition, we revisit the main functions and mechanisms of LINC00152 as driver oncogene and biomarker in pan-cancer. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Methods > RNA Analyses in Cells RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.

LINC01852 inhibits the tumorigenesis and chemoresistance in colorectal cancer by suppressing SRSF5-mediated alternative splicing of PKM

BACKGROUND

Colorectal cancer (CRC) is a major cause of cancer-related deaths worldwide, and chemoresistance is a major obstacle in its treatment. Despite advances in therapy, the molecular mechanism underlying chemoresistance in CRC is not fully understood. Recent studies have implicated the key roles of long noncoding RNAs (lncRNAs) in the regulation of CRC chemoresistance.

METHODS

In this study, we investigated the role of the lncRNA LINC01852 in CRC chemoresistance. LINC01852 expression was evaluated in multiple CRC cohorts using quantitative reverse transcription PCR. We conducted in vitro and in vivo functional experiments using cell culture and mouse models. RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation, and dual luciferase assays were used to investigate the molecular mechanism of LINC01852 in CRC.

RESULTS

Our findings revealed that a lncRNA with tumor-inhibiting properties, LINC01852, was downregulated in CRC and inhibited cell proliferation and chemoresistance both in vitro and in vivo. Further mechanistic investigations revealed that LINC01852 increases TRIM72-mediated ubiquitination and degradation of SRSF5, inhibiting SRSF5-mediated alternative splicing of PKM and thereby decreasing the production of PKM2. Overexpression of LINC01852 induces a metabolic switch from aerobic glycolysis to oxidative phosphorylation, which attenuates the chemoresistance of CRC cells by inhibiting PKM2-mediated glycolysis.

CONCLUSIONS

Our results demonstrate that LINC01852 plays an important role in repressing CRC malignancy and chemoresistance by regulating SRSF5-mediated alternative splicing of PKM, and that targeting the LINC01852/TRIM72/SRSF5/PKM2 signaling axis may represent a potential therapeutic strategy for CRC.

EZH2 as a potential therapeutic target for gastrointestinal cancers

Gastrointestinal (GI) cancers continue to be a major cause of mortality and morbidity globally. Understanding the molecular pathways associated with cancer progression and severity is essential for creating effective cancer treatments. In cancer research, there is a notable emphasis on Enhancer of zeste homolog 2 (EZH2), a key player in gene expression influenced by its irregular expression and capacity to attach to promoters and alter methylation status. This review explores the impact of EZH2 signaling on various GI cancers, such as colorectal, gastric, pancreatic, hepatocellular, esophageal, and cholangiocarcinoma. The primary function of EZH2 signaling is to facilitate the accelerated progression of cancer cells. Additionally, EZH2 has the capacity to modulate the reaction of GI cancers to chemotherapy and radiotherapy. Numerous pathways, including long non-coding RNAs and microRNAs, serve as upstream regulators of EZH2 in these types of cancer. EZH2's enzymatic activity enables it to attach to target gene promoters, resulting in methylation that modifies their expression. EZH2 could be considered as an independent prognostic factor, with increased expression correlating with a worse disease prognosis. Additionally, a range of gene therapies including small interfering RNA, and anti-tumor agents are being explored to target EZH2 for cancer treatment. This comprehensive review underscores the current insights into EZH2 signaling in gastrointestinal cancers and examines the prospect of therapies targeting EZH2 to enhance patient outcomes.

The Critical Function of microRNAs in Developing Resistance against 5- Fluorouracil in Cancer Cells

Although there have been significant advancements in cancer treatment, resistance and recurrence in patients make it one of the leading causes of death worldwide. 5-fluorouracil (5-FU), an antimetabolite agent, is widely used in treating a broad range of human malignancies. The cytotoxic effects of 5-FU are mediated by the inhibition of thymidylate synthase (TYMS/TS), resulting in the suppression of essential biosynthetic activity, as well as the misincorporation of its metabolites into RNA and DNA. Despite its huge benefits in cancer therapy, the application of 5-FU in the clinic is restricted due to the occurrence of drug resistance. MicroRNAs (miRNAs) are small, non-coding RNAs that act as negative regulators in many gene expression processes. Research has shown that changes in miRNA play a role in cancer progression and drug resistance. This review examines the role of miRNAs in 5-FU drug resistance in cancers.

The potential relevance of long non-coding RNAs in colorectal cancer pathogenesis and treatment: A review focus on signaling pathways

Colorectal cancer (CRC) is one of the most frequent cancers in incidence and mortality. Despite advances in cancer biology, molecular genetics, and targeted treatments, CRC prognosis and survival have not kept pace. This is usually due to advanced staging and metastases at diagnosis. Thus, great importance has been placed upon understanding the molecular pathophysiology behind the development of CRC, which has highlighted the significance of non-coding RNA's role and associated intracellular signaling pathways in the pathogenesis of the disease. According to recent studies, long non-coding RNAs (lncRNA), a subtype of ncRNAs whose length exceeds 200 nucleotides, have been found to have regulatory functions on multiple levels. Their actions at the transcription, post-transcriptional, translational levels, and epigenetic regulation have made them prime modulators of gene expression. Due to their role in cellular cancer hallmarks, their dysregulation has been linked to several illnesses, including cancer. Furthermore, their clinical relevance has expanded due to their possible detection in blood which has cemented them as potential future biomarkers and thus, potential targets for new therapy. This review will highlight the importance of lncRNAs and related signaling pathways in the development of CRC and their subsequent clinical applications.

Targeting LINC00152 activates cAMP/Ca2+/ferroptosis axis and overcomes tamoxifen resistance in ER+ breast cancer

Tamoxifen has been the mainstay therapy to treat early, locally advanced, and metastatic estrogen receptor-positive (ER+) breast cancer, constituting around 75% of all cases. However, emergence of resistance is common, necessitating the identification of novel therapeutic targets. Here, we demonstrated that long-noncoding RNA LINC00152 confers tamoxifen resistance via blocking tamoxifen-induced ferroptosis, an iron-mediated cell death. Mechanistically, inhibiting LINC00152 reduces the mRNA stability of phosphodiesterase 4D (PDE4D), leading to activation of cAMP/PKA/CREB axis and increased expression of TRPC1 Ca2+ channel. This causes cytosolic Ca2+ overload and generation of reactive oxygen species (ROS) that is, on one hand, accompanied by downregulation of FTH1, a member of the iron sequestration unit, thus increasing intracellular Fe2+ levels; and on the other hand, inhibition of the peroxidase activity upon reduced GPX4 and xCT levels. These ultimately induce lipid peroxidation and ferroptotic cell death in combination with tamoxifen. Overexpressing PDE4D rescues LINC00152 inhibition-mediated tamoxifen sensitization by de-activating the cAMP/Ca2+/ferroptosis axis. Importantly, high LINC00152 expression is significantly correlated with high PDE4D/low ferroptosis and worse survival in multiple cohorts of tamoxifen- or tamoxifen-containing endocrine therapy-treated ER+ breast cancer patients. Overall, we identified LINC00152 inhibition as a novel mechanism of ferroptosis induction and tamoxifen sensitization, thereby revealing LINC00152 and its effectors as actionable therapeutic targets to improve clinical outcome in refractory ER+ breast cancer.

LncRNA-miRNA interaction is involved in colorectal cancer pathogenesis by modulating diverse signaling pathways

LncRNAs function as molecular sponges for miRNAs to control their availability for targeting mRNA molecules. This procedure indirectly regulates the expression of cancer-related genes. Some lncRNAs also directly interact with miRNAs, leading to their degradation or sequestration, which can negatively impact gene expression. miRNAs, on the other hand, play a critical role in controlling the expression of genes, including oncogenes and tumor suppressor genes. Multiple types of cancer have been linked to the onset and progression of miRNA dysregulation. Even though there is a lot of potential for treating CRC by targeting the LncRNA-miRNA axis, several challenges remain to be overcome. The specificity of the targeting approach, delivery methods, resistance, safety, and cost-effectiveness are critical research areas that must be addressed to advance this field and improve treatment outcomes for people with CRC.

Serum LINC00152 and UCA1 in HCV-Induced Hepatocellular Carcinoma: Clinical Significance and Prognostic Value

Background

Despite significant advancements in the molecular characterization of hepatocellular carcinoma (HCC), no oncogene addiction has been discovered. Long noncoding RNAs (lncRNAs) have a lot of promise as cancer biomarkers. LINC00152 and UCA1 have shown potential as diagnostic, prognostic, and therapeutic targets for human cancers.

Aim

To investigate the diagnostic and prognostic potential of serum LINC00152 and UCA1 in hepatocellular carcinoma (HCC).

Methods

The expression levels of LINC00152 and UCA1 in blood samples from 120 patients (60 with HCC, 60 with liver cirrhosis) and 40 healthy subjects were assessed using real-time qRT-PCR.

Results

Serum LINC00152 and UCA1 expression were considerably higher in HCC patients compared to patients with liver cirrhosis and the healthy controls (p<0.001 and p<0.001 respectively). And their expressions in the liver cirrhosis group were significantly higher than in healthy controls. Both lncRNAs performed well in the ROC analysis, distinguishing HCC patients from patients with liver cirrhosis. Higher levels of LINC00152 expression were linked to lesions in both lobes of the liver (p=0.02), while higher levels of UCA1 expression were linked to vascular invasion and the late stage (p=0.01, p=0.03 respectively). The multivariate analysis showed that a high level of LINC00152 in the blood was an independent indicator of a bad outcome for HCC patients (HR=2.23, 95% CI= 1.30-5.29, p=0.03).

Conclusion

Serum LINC00152 and UCA1 expression were upregulated in patients with HCC, suggesting their use as non-invasive biomarkers for HCC. Furthermore, LINC00152 has the potential to serve as a prognostic indicator.

Integrative Analysis Revealed LINC00847 as a Potential Target of Tumor Immunotherapy

Lung cancer is the second most commonly diagnosed cancer and the leading cause of cancer-related death. Lung adenocarcinoma (LUAD) is the most common form of lung cancer and has a low 5-year survival rate. Therefore, much more research is needed to identify cancer biomarkers, promote biomarker-driven therapy and improve treatment outcomes. LncRNAs have been reported to participate in various physiological and pathological processes, especially in cancer, and thus have attracted much attention. In this study, lncRNAs were screened from the single-cell RNA-seq dataset CancerSEA. Among them, four lncRNAs (HCG18, NNT-AS1 and LINC00847 and CYTOR) were closely associated with the prognosis of LUAD patients according to Kaplan-Meier analysis. Further study explored the correlations between these four lncRNAs and immune cell infiltration in cancer. In LUAD, LINC00847 was positively correlated with the immune infiltration of B cells, CD8 T cells, and dendritic cells. LINC00847 decreased the expression of PD-L1, immune checkpoint blockade (ICB) immunotherapy-related gene, which suggests that LINC00847 is a potential new target for tumor immunotherapy.

Acetylation of aldehyde dehydrogenase ALDH1L2 regulates cellular redox balance and the chemosensitivity of colorectal cancer to 5-fluorouracil

Folate-mediated one-carbon metabolism (FOCM) is crucial in sustaining rapid proliferation and survival of cancer cells. The folate cycle depends on a series of key cellular enzymes, including aldehyde dehydrogenase 1 family member L2 (ALDH1L2) that is usually overexpressed in cancer cells, but the regulatory mechanism of ALDH1L2 remains undefined. In this study, we observed the significant overexpression of ALDH1L2 in colorectal cancer (CRC) tissues, which is associated with poor prognosis. Mechanistically, we identified that the acetylation of ALDH1L2 at the K70 site is an important regulatory mechanism inhibiting the enzymatic activity of ALDH1L2 and disturbing cellular redox balance. Moreover, we revealed that sirtuins 3 (SIRT3) directly binds and deacetylates ALDH1L2 to increase its activity. Interestingly, the chemotherapeutic agent 5-fluorouracil (5-Fu) inhibits the expression of SIRT3 and increases the acetylation levels of ALDH1L2 in colorectal cancer cells. 5-Fu-induced ALDH1L2 acetylation sufficiently inhibits its enzymatic activity and the production of NADPH and GSH, thereby leading to oxidative stress-induced apoptosis and suppressing tumor growth in mice. Furthermore, the K70Q mutant of ALDH1L2 sensitizes cancer cells to 5-Fu both in vitro and in vivo through perturbing cellular redox and serine metabolism. Our findings reveal an unknown 5-Fu-SIRT3-ALDH1L2 axis regulating redox homeostasis, and suggest that targeting ALDH1L2 is a promising therapeutic strategy to sensitize tumor cells to chemotherapeutic agents.

Interaction of lncRNAs with mTOR in colorectal cancer: a systematic review

Colorectal cancer (CRC) is the third most widespread cancer and the fourth leading lethal disease among different societies. It is thought that CRC accounts for about 10% of all newly diagnosed cancer cases with high-rate mortality. lncRNAs, belonging to non-coding RNAs, are involved in varied cell bioactivities. Emerging data have confirmed a significant alteration in lncRNA transcription under anaplastic conditions. This systematic review aimed to assess the possible influence of abnormal mTOR-associated lncRNAs in the tumorigenesis of colorectal tissue. In this study, the PRISMA guideline was utilized based on the systematic investigation of published articles from seven databases. Of the 200 entries, 24 articles met inclusion criteria and were used for subsequent analyses. Of note, 23 lncRNAs were prioritized in association with the mTOR signaling pathway with up-regulation (79.16%) and down-regulation (20.84%) trends. Based on the obtained data, mTOR can be stimulated or inhibited during CRC by the alteration of several lncRNAs. Determining the dynamic activity of mTOR and relevant signaling pathways via lncRNAs can help us progress novel molecular therapeutics and medications.

SNHG15 promotes chemoresistance and glycolysis in colorectal cancer

Long noncoding RNAs (lncRNAs) play an important role in tumor progression. Small nucleolar RNA host gene 15 (SNHG15) is a lncRNA that has been confirmed to play an oncogenic role in multiple cancer types. However, its role in glycolysis and chemoresistance in colorectal cancer (CRC) is unclear. The expression of SNHG15 in CRC was analyzed using data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases by bioinformatics methods. Cell Counting Kit-8 (CCK-8) and colony formation assays were used to evaluate cell viability. Cell sensitivity to 5-fluorouracil (5-FU) was detected by CCK-8. Glucose absorption and lactate production were used to evaluate the impact of SNHG15 on glycolysis. RNA-seq, real-time fluorescence quantitative reverse transcription PCR (RT-qPCR) and Western blotting (WB) were used to reveal the potential molecular mechanism of SNHG15 in CRC. SNHG15 was upregulated in CRC tissues compared with paired noncancerous tissues. Ectopic SNHG15 expression increased proliferation, 5-FU chemoresistance, and glycolysis in CRC cells. In contrast, SNHG15 knockdown inhibited CRC proliferation, 5-FU chemoresistance and glycolysis. Multiple pathways, including apoptosis and glycolysis, were potentially regulated by SNHG15 based on RNA-seq and pathway enrichment analyses. RT-qPCR and WB experiments confirmed that SNHG15 promoted the expression of TYMS, BCL2, GLUT1 and PKM2 in CRC cells. In conclusion, SNHG15 promotes 5-FU chemoresistance and glycolysis in CRC by potentially regulating the expression of TYMS, BCL2, GLUT1 and PKM2 and appears to be a new target for cancer therapy.

A glimpse of research cores and frontiers on the relationship between long noncoding RNAs (lncRNAs) and colorectal cancer (CRC) using the VOSviewer tool

As lncRNAs are essential participants in colorectal carcinogenesis. This study aimed to use the VOSviewer tool to access the research cores and frontiers on the relationship between lncRNAs and CRC. Our findings showed that the mechanism of lncRNA in the occurrence and development of CRC was the core theme of the field. (1) Immunotherapy and immune microenvironment of CRC and lncRNAs, (2) CRC and lncRNAs in exosomes and (3) CRC and lncRNA-targeted therapy might represent three research frontiers. A comprehensive understanding of their existing mechanisms and the search for new regulatory paradigms are the core topics of future research. This knowledge will also help us select appropriate targeting methods and select appropriate preclinical models to promote clinical translation and ultimately achieve precise treatment of CRC.

The Long Noncoding RNA Cytoskeleton Regulator RNA (CYTOR)/miRNA-24-3p Axis Facilitates Nasopharyngeal Carcinoma Progression by Modulating GAD1 Expression

Nasopharyngeal carcinoma (NPC) is a head and neck epithelial carcinoma that is unusually prevalent in Southeast Asia. Noncoding RNAs, including lncRNA and miRNA, and their target genes are considered vital regulators of tumorigenesis and the progression of NPC. However, the detailed underlying mechanisms of GAD1 involved in the regulation of NPC need to be further elucidated. In the present study, we identified that GAD1 was significantly upregulated in NPC tissues. GAD1 overexpression is promoted, while genetic knockdown of GAD1 suppresses proliferation, colony formation, migration, and invasion of NPC cells. Bioinformatics analysis and a luciferase reporter assay demonstrated that GAD1 is a direct target gene of miR-24-3p. In NPC tissues, miR-24-3p was downregulated and the lncRNA CYTOR was upregulated. CYTOR was sponged to suppress the function of miR-24-3p. CYTOR regulates GAD1 expression via modulating miR-24-3p. The CYTOR/miR-24-3p/GAD1 axis is converged to modulate the growth, migration, and invasion of NPC cells. In conclusion, the study identified a novel axis for the regulation of NPC cell growth, providing new insights into the understanding of NPC.

A review on the role of LINC00152 in different disorders

LINC00152 is an important lncRNA in human disorders. It is mainly regarded as a tumor-promoting lncRNA. Mechanistically, LINC00152 serves as a molecular sponge for miR-143a-3p, miR-125a-5p, miR-139, miR-215, miR-193a/b-3p, miR-16-5p, miR-206, miR-195, miR-138, miR-185-5p, miR-103, miR-612, miR-150, miR-107, miR-205-5p and miR-153-3p. In addition, it can regulate activity of mTOR, EGFR/PI3K/AKT, ERK/MAPK, Wnt/β-Catenin, EGFR, NF-κB, HIF-1 and PTEN. In this review, we provide a concise but comprehensive explanation about the role of LINC00152 in tumor development and progression as well as its role in the pathology of non-malignant conditions with the aim of facilitating the clinical implementation of this lncRNA as a diagnostic or prognostic tumor marker and therapeutic target.

The role of LncRNA MCM3AP-AS1 in human cancer

Long noncoding RNAs (lncRNA) play pivotal roles in every level of gene and genome regulation. MCM3AP-AS1 is a lncRNA that has an oncogenic role in several kinds of cancers. Aberrant expression of MCM3AP-AS1 has been reported to be involved in the progression of diverse malignancies, including colorectal, cervical, prostate, lymphoma, lung, ovary, liver, bone, and breast cancers. It is generally believed that MCM3AP-AS1 expression is associated with cancer cell growth, proliferation, angiogenesis, and metastasis. MCM3AP-AS1 by targeting various signaling pathways and microRNAs (miRNAs) presents an important role in cancer pathogenesis. MCM3AP-AS1 as a competitive endogenous RNA has the ability to sponge miRNA, inhibit their expressions, and bind to different target mRNAs related to cancer development. Therefore, MCM3AP-AS1 by targeting several signaling pathways, including the FOX family, Wnt, EGF, and VEGF can be a potent target for cancer prediction and diagnosis. In this review, we will summarize the role of MCM3AP-AS1 in various human cancers.

Effects of Long Non-Coding RNAs Induced by the Gut Microbiome on Regulating the Development of Colorectal Cancer

Although an imbalanced gut microbiome is closely associated with colorectal cancer (CRC), how the gut microbiome affects CRC is not known. Long non-coding RNAs (lncRNAs) can affect important cellular functions such as cell division, proliferation, and apoptosis. The abnormal expression of lncRNAs can promote CRC cell growth, proliferation, and metastasis, mediating the effects of the gut microbiome on CRC. Generally, the gut microbiome regulates the lncRNAs expression, which subsequently impacts the host transcriptome to change the expression of downstream target molecules, ultimately resulting in the development and progression of CRC. We focused on the important role of the microbiome in CRC and their effects on CRC-related lncRNAs. We also reviewed the impact of the two main pathogenic bacteria, Fusobacterium nucleatum and enterotoxigenic Bacteroides fragilis, and metabolites of the gut microbiome, butyrate, and lipopolysaccharide, on lncRNAs. Finally, available therapies that target the gut microbiome and lncRNAs to prevent and treat CRC were proposed.

Long noncoding RNA DLGAP1-AS2 promotes tumorigenesis and metastasis by regulating the Trim21/ELOA/LHPP axis in colorectal cancer

Background

Long noncoding RNAs (lncRNAs) have driven research focused on their effects as oncogenes or tumor suppressors involved in carcinogenesis. However, the functions and mechanisms of most lncRNAs in colorectal cancer (CRC) remain unclear.

Methods

The expression of DLGAP1-AS2 was assessed by quantitative RT-PCR in multiple CRC cohorts. The impacts of DLGAP1-AS2 on CRC growth and metastasis were evaluated by a series of in vitro and in vivo assays. Furthermore, the underlying mechanism of DLGAP1-AS2 in CRC was revealed by RNA pull down, RNA immunoprecipitation, RNA sequencing, luciferase assays, chromatin immunoprecipitation, and rescue experiments.

Results

We discovered that DLGAP1-AS2 promoted CRC tumorigenesis and metastasis by physically interacting with Elongin A (ELOA) and inhibiting its protein stability by promoting tripartite motif containing 21 (Trim21)-mediated ubiquitination modification and degradation of ELOA. In particular, we revealed that DLGAP1-AS2 decreases phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) expression by inhibiting ELOA-mediated transcriptional activating of LHPP and thus blocking LHPP-dependent suppression of the AKT signaling pathway. In addition, we also demonstrated that DLGAP1-AS2 was bound and stabilized by cleavage and polyadenylation specificity factor (CPSF2) and cleavage stimulation factor (CSTF3).

Conclusions

The discovery of DLGAP1-AS2, a promising prognostic biomarker, reveals a new dimension into the molecular pathogenesis of CRC and provides a prospective treatment target for this disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01675-w.

Notch-associated lncRNAs profiling circuiting epigenetic modification in colorectal cancer

Background

Colorectal cancer (CRC) is one of the most prevalent digestive cancers, ranking the 2nd cause of cancer-related fatality worldwide. The worldwide burden of CRC is predicted to rise by 60% by 2030. Environmental factors drive, first, inflammation and hence, cancer incidence increase.

Main

The Notch-signaling system is an evolutionarily conserved cascade, has role in the biological normal developmental processes as well as malignancies. Long non-coding RNAs (LncRNAs) have become major contributors in the advancement of cancer by serving as signal pathways regulators. They can control gene expression through post-translational changes, interactions with micro-RNAs or down-stream effector proteins. Recent emerging evidence has emphasized the role of lncRNAs in controlling Notch-signaling activity, regulating development of several cancers including CRC.

Conclusion

Notch-associated lncRNAs might be useful prognostic biomarkers or promising potential therapeutic targets for CRC treatment.

Therefore, here-in we will focus on the role of “Notch-associated lncRNAs in CRC” highlighting “the impact of Notch-associated lncRNAs as player for cancer induction and/or progression.”

Graphical Abstract

Apoptosis evasion via long non-coding RNAs in colorectal cancer

Long non-coding RNA (LncRNA) is a novel and diverse class of regulatory transcripts that are frequently dysregulated in numerous tumor types. LncRNAs are involved in a complicated molecular network, regulating gene expression, and modulating diverse cellular activities in different cancers including colorectal cancer (CRC). Evidence indicates that lncRNAs can be used as a potential biomarker for the prognosis and diagnosis of CRC as they are aberrantly expressed in CRC cells. The high expression or silencing of lncRNAs is associated with cell proliferation, invasion, metastasis, chemoresistance and apoptosis in CRC. LncRNAs exert both pro-apoptotic and anti-apoptotic functions in CRC. The expression of some oncogene lncRNAs is upregulated which leads to the inhibition of apoptotic pathways, similarly, the tumor suppressor lncRNAs are downregulated in CRC. In this review, we describe the function and mechanisms of lncRNAs to regulate the expression of genes that are involved directly or indirectly in controlling cellular apoptosis in CRC. Furthermore, we also discussed the different apoptotic pathways in normal cells and the mechanisms by which CRC evade apoptosis.

ZNF750 facilitates carcinogenesis via promoting the expression of long non-coding RNA CYTOR and influences pharmacotherapy response in colon adenocarcinoma

The epidermal cell differentiation regulator zinc finger protein 750 (ZNF750) is a transcription factor containing the Cys2His2 (C2H2) domain, the zinc finger structure of which is located at the N-terminal 25‍‍-‍46 amino acids of ZNF750. It can promote the expression of differentiation-related factors while inhibiting the expression of progenitor cell-related genes. ZNF750 is directly regulated by p63 (encoded by the TP63 gene, belonging to the TP53 superfamily). The Krüppel-like factor 4 (KLF4), repressor element-1 (RE-1)‍-silencing transcription factor (REST) corepressor 1 (RCOR1), lysine demethylase 1A (KDM1A), and C-terminal-binding protein 1/2 (CTBP1/2) chromatin regulators cooperate with ZNF750 to repress epidermal progenitor genes and activate the expression of epidermal terminal differentiation genes (Sen et al., 2012; Boxer et al., 2014). Besides, ZNF750 and the regulatory network composed of bone morphogenetic protein (BMP) signaling pathway, long non-coding RNAs (lncRNAs) (anti-differentiation non-coding RNA (ANCR) and tissue differentiation-inducing non-protein coding RNA (TINCR)), musculoaponeurotic fibrosarcoma oncogene (MAF)/MAF family B (MAFB), grainy head-like 3 (GRHL3), and positive regulatory domain zinc finger protein 1 (PRDM1) jointly promote epidermal cell differentiation (Sen et al., 2012).

Identification of EMT-Related lncRNAs as Potential Prognostic Biomarkers and Therapeutic Targets for Pancreatic Adenocarcinoma

Epithelial-mesenchymal transition (EMT) can promote carcinoma progression by multiple mechanisms; many studies demonstrated the invasiveness of pancreatic adenocarcinoma (PAAD) associated with the EMT, but how it acts through an lncRNA-dependent manner is unknown. Here, we investigated 146 samples from The Cancer Genome Atlas (TCGA) and 92 samples from the International Cancer Genome Consortium (ICGC). By gene set variation analysis (GSVA) and weighted correlation network analysis (WGCNA), we explored the EMT-related long noncoding RNAs (EMTlnc). Then, we performed univariate Cox regression analysis to screen their prognostic value for PAAD. The least absolute contraction and selection operator (LASSO) Cox regression was used to establish EMT-related lncRNA prognostic signal (EMT-LPS). In addition, we established a competitive endogenous ceRNA network. Then, we identified 33 prognostic EMTlnc as prognostic lncRNAs and established an EMT-LPS which showed strong prognostic ability in stratification analysis. By corresponding risk scores, patients were divided into low-risk and high-risk subgroups. Principal component analysis (PCA) showed that these subgroups had individual EMT status. Enrichment analysis showed that in the high-risk subgroup, biological processes, pathways, and hallmarks related to malignant tumors are more common. What is more, we constructed a nomogram that had powerful ability to predict the overall survival rate (OS) of PAAD patients in two datasets. So, EMT-LPS are a principal element in PAAD's carcinoma progression and may help us in choosing the way of prognosis assessment and provide some clues to design the new drugs for PAAD.

SLCO4A1-AS1 promotes colorectal tumourigenesis by regulating Cdk2/c-Myc signalling

BACKGROUND

SLCO4A1-AS1 was found to be upregulated in several cancer types, including colorectal cancer (CRC). However, the detailed roles of SLCO4A1-AS1 in CRC remain to be elucidated. Therefore, we investigated the functions, mechanism, and clinical significance of SLCO4A1-AS1 in colorectal tumourigenesis.

METHODS

We measured the expression of SLCO4A1-AS1 in CRC tissues using qRT-PCR and determined its correlation with patient prognosis. Promoter methylation analyses were used to assess the methylation status of SLCO4A1-AS1. Gain- and loss-of-function assays were used to evaluate the effects of SLCO4A1-AS1 on CRC growth in vitro and in vivo. RNA pull-down, RNA immunoprecipitation, RNA-seq, luciferase reporter and immunohistochemistry assays were performed to identify the molecular mechanism of SLCO4A1-AS1 in CRC.

RESULTS

SLCO4A1-AS1 was frequently upregulated in CRC tissues based on multiple CRC cohorts and was associated with poor prognoses. Aberrant overexpression of SLCO4A1-AS1 in CRC is partly attributed to the DNA hypomethylation of its promoter. Ectopic SLCO4A1-AS1 expression promoted CRC cell growth, whereas SLCO4A1-AS1 knockdown repressed CRC proliferation both in vitro and in vivo. Mechanistic investigations revealed that SLCO4A1-AS1 functions as a molecular scaffold to strengthen the interaction between Hsp90 and Cdk2, promoting the protein stability of Cdk2. The SLCO4A1-AS1-induced increase in Cdk2 levels activates the c-Myc signalling pathway by promoting the phosphorylation of c-Myc at Ser62, resulting in increased tumour growth.

CONCLUSIONS

Our data demonstrate that SLCO4A1-AS1 acts as an oncogene in CRC by regulating the Hsp90/Cdk2/c-Myc axis, supporting SLCO4A1-AS1 as a potential therapeutic target and prognostic factor for CRC.

LncRNA UCA1 mediates Cetuximab resistance in Colorectal Cancer via the MiR-495 and HGF/c-MET Pathways

Background: Cetuximab is one of the most widely used monoclonal antibodies to treat patients with RAS/BRAF wild-type metastatic colorectal cancer (mCRC). Unfortunately, cetuximab resistance often occurs during targeted therapy. However, the underlying epigenetic mechanisms remain unclear. Our previous study demonstrated that the exosomal transfer of urothelial carcinoma-associated 1 (UCA1) confers cetuximab resistance to CRC cells. The goal of this study was to elucidate the detailed role of UCA1 in cetuximab resistance in CRC and the underlying molecular mechanism.

Methods:In vitro and in vivo functional studies were performed to assess the role of UCA1 in cetuximab resistance in CRC cell lines and xenograft models. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to examine UCA1 localization and expression. Bioinformatics analysis was performed to predict the potential mechanism of UCA1, which was further validated by the dual-luciferase reporter assay and the RNA immunoprecipitation (RIP) assay. Cells treated with indicators were subjected to Cell Counting Kit-8 (CCK-8) and western blotting to investigate the role of hepatocyte growth factor (HGF)/c-mesenchymal-epithelial transition (c-MET) signalling in UCA1-mediated cetuximab resistance.

Results: We showed that UCA1 decreased CRC cell sensitivity to cetuximab by suppressing apoptosis. Mechanistic studies revealed that UCA1 promoted cetuximab resistance by competitively binding miR-495 to facilitate HGF and c-MET expression in CRC cells. Moreover, HGF was shown to attenuate the cetuximab-induced inhibition of cell proliferation by activating the HGF/c-MET pathway in CRC cells.

Conclusion: We provide the first evidence of a UCA1-miR-495-HGF/c-MET regulatory network involved in cetuximab resistance in CRC. Therefore, UCA1 has potential as a predictor and therapeutic target for cetuximab resistance.

Long Non-coding RNAs, Lnc(ing) RNA Metabolism to Cancer Biology

The eukaryotic genome is represented by a vast proportion of non-coding regions, which in recent years have been attributed to have important functional roles in gene regulation through a myriad of processes, ranging from proper localization, correct folding and, most importantly, spatial and temporally regulated expression of genes. One of the major contributing factors in these processes is ribonucleic acid (RNA) metabolism, which comprises the RNA-nucleoprotein (RNP) complexes that interact with and instruct the genome to function. Long non-coding RNAs are an integral component of several RNPs, and herein we provide an overview of the understanding of the long non-coding RNAs, their characteristics, their function and their balancing act as dual modulators in cancer manifestation and progression.

The Relationship Between the Network of Non-coding RNAs-Molecular Targets and N6-Methyladenosine Modification in Colorectal Cancer

Recent accumulating researches implicate that non-coding RNAs (ncRNAs) including microRNA (miRNA), circular RNA (circRNA), and long non-coding RNA (lncRNAs) play crucial roles in colorectal cancer (CRC) initiation and development. Notably, N6-methyladenosine (m⁶A) methylation, the critical posttranscriptional modulators, exerts various functions in ncRNA metabolism such as stability and degradation. However, the interaction regulation network among ncRNAs and the interplay with m⁶A-related regulators has not been well documented, particularly in CRC. Here, we summarize the interaction networks and sub-networks of ncRNAs in CRC based on a data-driven approach from the publications (IF > 6) in the last quinquennium (2016–2021). Further, we extend the regulatory pattern between the core m⁶A regulators and m⁶A-related ncRNAs in the context of CRC metastasis and progression. Thus, our review will highlight the clinical potential of ncRNAs and m⁶A modifiers as promising biomarkers and therapeutic targets for improving the diagnostic precision and treatment of CRC.

A proposed Information-Based modality for the treatment of cancer

Treatment modalities for cancer involve physical manipulations such as surgery, immunology, radiation, chemotherapy or gene editing. This is a proposal for an information-based modality. This modality does not change the internal state of the cancer cell directly - instead, the cancer cell is manipulated by giving it information to instruct the cell to perform an action. This modality is based on a theory of Structure Encoding in DNA, where information about body part structure controls the epigenetic state of cells in the process of development from pluripotent cells to fully differentiated cells. It has been noted that cancer is often due to errors in morphogenetic differentiation accompanied by associated epigenetic processes. This implies a model of cancer called the Epigenetic Differentiation Model. A major feature of the Structure Encoding Theory is that the characteristics of the differentiated cell are affected by inter-cellular information passed in the tissue microenvironment, which specifies the exact location of a cell in a body part structure. This is done by exosomes that carry fragments of long non-coding RNA and transposons, which convey structure information. In the normal process of epigenetic differentiation, the information passed may lead to apoptosis due to the constraints of a particular body part structure. The proposed treatment involves determining what structure information is being passed in a particular tumor, then adding artificial exosomes that overwhelm the current information with commands for the cells to go into apoptosis.

Long noncoding RNA CRART16 confers 5-FU resistance in colorectal cancer cells by sponging miR-193b-5p

Background

The emergence of chemoresistance to 5-fluorouracil (5-FU)-based chemotherapy is the main cause of treatment failure in advanced and metastatic colorectal cancer (CRC) patients. Long noncoding RNAs (lncRNAs) have been reported to be involved in 5-FU resistance. Previously, we first detected that lncRNA cetuximab resistance-associated RNA transcript 16 (CRART16) could contribute to cetuximab resistance by upregulating V-Erb-B2 erythroblastic leukemia viral oncogene homologue 3 (ERBB3) expression by sponging miR-371a-5p in CRC cells. The current study aimed to explore the role of CRART16 in acquired 5-FU resistance in CRC cells and its possible mechanism.

Methods

Quantitative real-time PCR (RT-qPCR) was used to measure the expression levels of CRART16 in a 5-FU-resistant CRC cell subline (SW620/5-FU) and the parent cell line. Lentivirus transduction was performed to establish SW620 and Caco-2 cells stably overexpressing CRART16. Cell Counting Kit-8 (CCK-8) assays and colony formation assays were applied to measure cell chemosensitivity to 5-FU. Flow cytometric and immunofluorescence staining were adopted to assess cell apoptosis induced by 5-FU. The dual-luciferase reporter assay was used to validate the direct interactions between CRART16 and miR-193b-5p and between miR-193b-5p and high-mobility group AT-hook-2 (HMGA2). The expression levels of HMGA2, apoptosis-associated proteins and p-ERK were examined by western blotting. The statistical differences within any two groups were used Student’s t test.

Results

CRART16 was upregulated in SW620/5-FU cells. Overexpression of CRART16 reduced the sensitivity of CRC cells to 5-FU by attenuating apoptosis. In addition, CRART16 promoted 5-FU resistance by suppressing the expression of miR-193b-5p. Furthermore, CRART16 modulated the expression of HMGA2 by inhibiting miR-193b-5p and activated the MAPK signaling pathway.

Conclusions

CRART16 confers 5-FU resistance in CRC cells through the CRART16/miR-193b-5p/HMGA2/MAPK pathway.

Protein-RNA interactome analysis reveals wide association of KSHV ORF57 with host non-coding RNAs and polysomes

Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 is an RNA-binding post-transcriptional regulator. We recently applied an affinity-purified anti-ORF57 antibody to conduct ORF57-CLIP (Cross-linking Immunoprecipitation) in combination with RNA-sequencing (CLIP-seq) and analyzed the genome-wide host RNA transcripts in association with ORF57 in BCBL-1 cells with lytic KSHV infection. Mapping of the CLIPed RNA reads to the human genome (GRCh37) revealed that most of the ORF57-associated RNA reads were from rRNAs. The remaining RNA reads mapped to several classes of host non-coding and protein-coding mRNAs. We found ORF57 binds and regulates expression of a subset of host lncRNAs, including LINC00324, LINC00355, and LINC00839 which are involved in cell growth. ORF57 binds snoRNAs responsible for 18S and 28S rRNA modifications, but does not interact with fibrillarin and NOP58. We validated ORF57 interactions with 67 snoRNAs by ORF57-RNA immunoprecipitation (RIP)-snoRNA-array assays. Most of the identified ORF57 rRNA binding sites (BS) overlap with the sites binding snoRNAs. We confirmed ORF57-snoRA71B RNA interaction in BCBL-1 cells by ORF57-RIP and Northern blot analyses using a ³²P-labeled oligo probe from the 18S rRNA region complementary to snoRA71B. Using RNA oligos from the rRNA regions that ORF57 binds for oligo pulldown-Western blot assays, we selectively verified ORF57 interactions with 5.8S and 18S rRNAs. Polysome profiling revealed that ORF57 associates with both monosomes and polysomes and its association with polysomes increases PABPC1 binding to, but prevent Ago2 from polysomes. Our data indicate a functional correlation with ORF57 binding and suppression of Ago2 activities for ORF57 promotion of gene expression. Significance As an RNA-binding protein, KSHV ORF57 regulates RNA splicing, stability, and translation and inhibits host innate immunity by blocking the formation of RNA granules in virus infected cells. In this report, ORF57 was found to interact many host non-coding RNAs, including lncRNAs, snoRNAs and ribosomal RNAs to carry out additional unknown functions. ORF57 binds a group of lncRNAs via the identified RNA motifs by ORF57 CLIP-seq to regulate their expression. ORF57 associates with snoRNAs independently of fibrillarin and NOP58 proteins, and with ribosomal RNA in the regions that commonly bind snoRNAs. Knockdown of fibrillarin expression decreases the expression of snoRNAs and CDK4, but not affect viral gene expression. More importantly, we found that ORF57 binds translationally active polysomes and enhances PABPC-1 but prevents Ago2 association with polysomes. Data provide a compelling evidence on how ORF57 in KSHV infected cells might regulate protein synthesis by blocking Ago2's hostile activities on translation.

SNHG17 promotes colorectal tumorigenesis and metastasis via regulating Trim23-PES1 axis and miR-339-5p-FOSL2-SNHG17 positive feedback loop

Background

Small nucleolar RNA host gene (SNHG) long noncoding RNAs (lncRNAs) are frequently dysregulated in human cancers and involved in tumorigenesis and progression. SNHG17 has been reported as a candidate oncogene in several cancer types, however, its regulatory role in colorectal cancer (CRC) is unclear.

Methods

SNHG17 expression in multiple CRC cohorts was assessed by RT-qPCR or bioinformatic analyses. Cell viability was evaluated using Cell Counting Kit-8 (CCK-8) and colony formation assays. Cell mobility and invasiveness were assessed by Transwell assays. Tumor xenograft and metastasis models were applied to confirm the effects of SNHG17 on CRC tumorigenesis and metastasis in vivo. Immunohistochemistry staining was used to measure protein expression in cancer tissues. RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation, and dual luciferase assays were used to investigate the molecular mechanism of SNHG17 in CRC.

Results

Using multiple cohorts, we confirmed that SNHG17 is aberrantly upregulated in CRC and correlated with poor survival. In vitro and in vivo functional assays indicated that SNHG17 facilitates CRC proliferation and metastasis. SNHG17 impedes PES1 degradation by inhibiting Trim23-mediated ubiquitination of PES1. SNHG17 upregulates FOSL2 by sponging miR-339-5p, and FOSL2 transcription activates SNHG17 expression, uncovering a SNHG17-miR-339-5p-FOSL2-SNHG17 positive feedback loop.

Conclusions

We identified SNHG17 as an oncogenic lncRNA in CRC and identified abnormal upregulation of SNHG17 as a prognostic risk factor for CRC. Our mechanistic investigations demonstrated, for the first time, that SNHG17 promotes tumor growth and metastasis through two different regulatory mechanisms, SNHG17-Trim23-PES1 axis and SNHG17-miR-339-5p-FOSL2-SNHG17 positive feedback loop, which may be exploited for CRC therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02162-8.

Regulation of signal transduction pathways in colorectal cancer: implications for therapeutic resistance

Resistance to anti-cancer treatments is a critical and widespread health issue that has brought serious impacts on lives, the economy and public policies. Mounting research has suggested that a selected spectrum of patients with advanced colorectal cancer (CRC) tend to respond poorly to both chemotherapeutic and targeted therapeutic regimens. Drug resistance in tumours can occur in an intrinsic or acquired manner, rendering cancer cells insensitive to the treatment of anti-cancer therapies. Multiple factors have been associated with drug resistance. The most well-established factors are the emergence of cancer stem cell-like properties and overexpression of ABC transporters that mediate drug efflux. Besides, there is emerging evidence that signalling pathways that modulate cell survival and drug metabolism play major roles in the maintenance of multidrug resistance in CRC. This article reviews drug resistance in CRC as a result of alterations in the MAPK, PI3K/PKB, Wnt/β-catenin and Notch pathways.

Metastatic colorectal cancer: Perspectives on long non-coding RNAs and promising therapeutics

Metastatic colorectal cancer (mCRC) has long been lethal despite the continuous efforts of researchers worldwide to discover and improve therapeutic regimens. Thanks to the emergence of long non-coding RNAs (lncRNAs), which has strongly reshaped our inherent perspectives on the pathophysiological patterns of disease, research in the field has been reinvigorated. Here, we focus on current understanding of the modes of action of lncRNAs, and review their regulatory roles in metastatic colorectal cancer, and discuss correlated potential lncRNA-based therapeutics. All of the discussed studies share clear and promising perspectives on future diagnostic and therapeutic remedies for metastatic colorectal cancer.

Research updates on the clinical implication of long noncoding RNA in digestive system cancers and chemoresistance

Long noncoding RNAs (lncRNAs) are implicated in various biological processes, such as cell proliferation, differentiation, apoptosis, migration, and invasion. They are also key players in various biological pathways. LncRNA was considered as 'translational noise' before 1980s. It has been reported that lncRNAs are aberrantly expressed in different cancers, either as oncogene or tumor suppressor gene. Therefore, more and more lncRNAs are recognized as potential diagnostic biomarkers and/or therapeutic targets. As competitive endogenous RNA, lncRNAs can interact with microRNA to alter the expression of target genes, which may have extensive clinical implications in cancers, including diagnosis, treatment, prognosis, and chemoresistance. This review comprehensively summarizes the functions and clinical relevance of lncRNAs in digestive system cancers, especially as a potential tool to overcome chemoresistance.

The Long Non-coding RNA Cytoskeleton Regulator (CYTOR) Sponges microRNA- 206 (miR-206) to Promote Proliferation and Invasion of HP75 Cells

BACKGROUND

The role and mechanism of long non-coding RNA cytoskeleton regulator (CYTOR) in Invasive Pituitary Adenomas (IPA) have not been elucidated previously.

OBJECTIVE

This study aimed to investigate the interaction between CYTOR and miR-206 and their roles in IPA using HP75 cells as the model.

METHODS

The expression levels of CYTOR and miR-206 were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in IPA tissues and cell lines. The Chi-square test was used to analyze the correlation between CYTOR expression and clinical-pathological parameters. HP75 cell proliferation was detected by Cell Counting Kit-8 assay and colony formation assay. Scratch healing experiments and Transwell assay were used to detect migration and invasion of HP75 cells. The relationship between CYTOR and miR-206 was predicted by bioinformatics and verified by qRT-PCR and the dual-luciferase reporter gene method.

RESULTS

CYTOR is up-regulated in IPA tissues and cell lines. The high expression of CYTOR is associated with adenoma invasiveness and adenoma size of the patients. Down-regulation of CYTOR decreases the proliferation, migration and invasion of HP75 cells, while up-regulation of miR-206 can inhibit proliferation, migration and invasion of HP75 cells. MiR-206 is identified as a target of CYTOR and could be negatively regulated by it in IPA.

DISCUSSION

CYTOR, as a tumor-promoting factor, facilitates the proliferation, migration and invasion of HP75 cells through sponging miR-206.

CONCLUSION

The CYTOR-miR-206 axis provides new insights into the diagnosis and treatment of IPA.

Recent Updates on Mechanisms of Resistance to 5-Fluorouracil and Reversal Strategies in Colon Cancer Treatment

5-Fluorouracil (5-FU) plus leucovorin (LV) remain as the mainstay standard adjuvant chemotherapy treatment for early stage colon cancer, and the preferred first-line option for metastatic colon cancer patients in combination with oxaliplatin in FOLFOX, or irinotecan in FOLFIRI regimens. Despite treatment success to a certain extent, the incidence of chemotherapy failure attributed to chemotherapy resistance is still reported in many patients. This resistance, which can be defined by tumor tolerance against chemotherapy, either intrinsic or acquired, is primarily driven by the dysregulation of various components in distinct pathways. In recent years, it has been established that the incidence of 5-FU resistance, akin to multidrug resistance, can be attributed to the alterations in drug transport, evasion of apoptosis, changes in the cell cycle and DNA-damage repair machinery, regulation of autophagy, epithelial-to-mesenchymal transition, cancer stem cell involvement, tumor microenvironment interactions, miRNA dysregulations, epigenetic alterations, as well as redox imbalances. Certain resistance mechanisms that are 5-FU-specific have also been ascertained to include the upregulation of thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase, and the downregulation of thymidine phosphorylase. Indeed, the successful modulation of these mechanisms have been the game plan of numerous studies that had employed small molecule inhibitors, plant-based small molecules, and non-coding RNA regulators to effectively reverse 5-FU resistance in colon cancer cells. It is hoped that these studies would provide fundamental knowledge to further our understanding prior developing novel drugs in the near future that would synergistically work with 5-FU to potentiate its antitumor effects and improve the patient's overall survival.

RP11-51O6.1 sponges miR-206 to accelerate colorectal cancer carcinogenesis and metastasis through upregulating YAP1

Long non-coding RNAs (lncRNAs) have been characterized by playing a crucial role in tumorigenesis. However, the detail biological function and clinical importance of lncRNAs in colorectal cancer (CRC) are unclear and have attracted different levels of in-depth research. In this context, we explored the differentially expressed profiles of lncRNAs in six CRC tissues and three adjacent non-tumor tissues from RNA-sequencing (RNA-seq) study and noted a lncRNA, RP11-51O6.1, which is markedly overexpressed in CRC tissues, particularly in aggressive cases. Impressively, an elevated RP11-51O6.1 level was highly correlated with poor prognosis in clinical patients. Functional analyses revealed that RP11-51O6.1 could promote cell proliferation in vitro and in vivo. Furthermore, we reported that RP11-51O6.1 enhances cell migration and invasion in vitro. Mechanistic studies (Bioinformatics binding site analyses, the Luciferase reporter, Ago2 immunoprecipitation, the RNA pull-down, immunofluorescence colocalization, rescued assays and western blotting) implicated that RP11-51O6.1 could regulate YAP1 expression by competitively sponging miR-206 and blocking its activity in promoting CRC progression. Conclusively, our findings identify a novel RP11-51O6.1/miR-206/YAP1 regulatory axis that participates in CRC progression and development, suggesting RP11-51O6.1 is an exploitable biomarker and appealing therapeutic target in treating CRC.

Comprehensive analysis of long non-coding RNA and mRNA expression profile in rectal cancer

BACKGROUND

Rectal cancer (RC) is a malignant tumor that seriously threatens human health. Long non-coding RNAs (lncRNAs) play a vital role in tumor regulation. Nevertheless, their exact expression features and functions remain obscure, and therefore was the aim of the current study.

METHODS

We utilized the Affymetrix human GeneChip to screen differentially expressed profiles of lncRNAs and mRNAs from the cancer tissues and matched paracancer tissues of 6 RC patients. Gene Ontology (GO) and pathway enrichment analyses identified crucial functions and pathways of the aberrantly expressed mRNAs. We used quantitative real-time polymerase chain reaction to verify the significant expression differences of 11 candidate lncRNAs between the cancer and paracancer tissues. LncRNA-mRNA coexpression networks were built by calculating the Pearson correlation value to identify significant correlation pairs. Online bioinformatics tools GEPIA2, ONCOMINE, and PROGgeneV2 were used to mine the expression and prognosis of three crucial mRNAs and six verified lncRNAs. Competing endogenous RNA networks were constructed by predicting microRNA response elements and calculating free energy.

RESULTS

We found 1658 differentially expressed lncRNAs (778 up-regulated and 880 down-regulated) and 1783 aberrantly expressed mRNAs (909 up-regulated and 874 down-regulated). GO and pathway enrichment analyses revealed the vital functions of the differentially expressed mRNAs, including cell proliferation, cell migration, angiogenesis, and cellular response to zinc ion. The canonical signaling pathways mainly included the interleukin-17, cell cycle, Wnt, and mineral absorption signaling pathways. Six lncRNAs including AC017002.2 (P = 0.039), cancer susceptibility 19 (CASC19) (P = 0.021), LINC00152 (P = 0.013), NONHSAT058834 (P = 0.007), NONHSAT007692 (P = 0.045), and ENST00000415991.1 (P = 0.045) showed significant differences in expression levels between the cancer tissue and paracancer tissue groups. AC017002.2, NONHSAT058834, NONHSAT007692, and ENST00000415991.1 have not yet been reported in RC. The crucial mRNAs myelocytomatosis viral oncogene (MYC), transforming growth factor beta induced (TGFBI), and solute carrier family 7 member 5 (SLC7A5) were selected. AC017002.2 and LINC00152 were positively correlated with MYC, TGFBI, and cytochrome P450 family 2 sub-family B member 6 (All r > 0.900, P < 0.050). NONHSAT058834 was positively associated with MYC (r = 0.930, P < 0.001), and CASC19 was positively correlated with SLC7A5 (r = 0.922, P < 0.001).

CONCLUSION

This study offers convincing evidence of differentially expressed lncRNAs and mRNAs as potential biomarkers in RC.

5-Fluorouracil: A Narrative Review on the Role of Regulatory Mechanisms in Driving Resistance to This Chemotherapeutic Agent

5-fluorouracil (5-FU) is among the mostly administrated chemotherapeutic agents for a wide variety of neoplasms. Non-coding RNAs have a central impact on the determination of the response of patients to 5-FU. These transcripts via modulation of cancer-related pathways, cell apoptosis, autophagy, epithelial-mesenchymal transition, and other aspects of cell behavior can affect cell response to 5-FU. Modulation of expression levels of microRNAs or long non-coding RNAs may be a suitable approach to sensitize tumor cells to 5-FU treatment via modulating multiple biological signaling pathways such as Hippo/YAP, Wnt/β-catenin, Hedgehog, NF-kB, and Notch cascades. Moreover, there is an increasing interest in targeting these transcripts in various kinds of cancers that are treated by 5-FU. In the present article, we provide a review of the function of non-coding transcripts in the modulation of response of neoplastic cells to 5-FU.

The Role of microRNAs in Development of Colitis-Associated Colorectal Cancer

Colorectal cancer (CRC) is the third most deadly cancer worldwide, and inflammatory bowel disease (IBD) is one of the critical factors in CRC carcinogenesis. IBD is responsible for an unphysiological and sustained chronic inflammation environment favoring the transformation. MicroRNAs (miRNAs) belong to a class of highly conserved short single-stranded segments (18-25 nucleotides) non-coding RNA and have been extensively discussed in both CRC and IBD. However, the role of miRNAs in the development of colitis-associated CRC (CAC) is less clear. The aim of this review is to summarize the major upregulated (miR-18a, miR-19a, miR-21, miR-31, miR-155 and miR-214) and downregulated (miR-124, miR-193a-3p and miR-139-5p) miRNAs in CAC, and their roles in genes' expression modulation in chronic colonic-inflammation-induced carcinogenesis, including programmed cell-death pathways. These miRNAs dysregulation could be applied for early CAC diagnosis, to predict therapy efficacy and for precision treatment.

LncRNA signature in colorectal cancer

Colorectal cancer (CRC) is among the most frequent cancers and is associated with high mortality particularly when being diagnosed in advanced stages. Although several environmental and intrinsic risk factors have been identified, the underlying cause of CRC is not clear in the majority of cases. Several studies especially in the recent decade have pointed to the role of epigenetic factors in this kind of cancer. Long non-coding RNAs (lncRNAs) as important contributors in the epigenetic mechanisms are involved in the initiation, progression and metastasis of CRC. Tens of oncogenic lncRNAs and a lower number of tumor suppressor lncRNAs have been recently identified to be dysregulated in CRC cells and tissues. Notably, expressions of a number of these transcripts have been dysregulated in serum samples of CRC patients, providing a non-invasive route for detection of this kind of cancer. The involvement of lncRNAs in the regulation of autophagy has provided them the ability to modulate response of CRC cells to chemotherapeutic modalities. In the current manuscript, we review the studies which evaluated the role of lncRNAs in the pathogenesis and progression of CRC to appraise their application as diagnostic/ prognostic markers.

Long noncoding RNA MCM3AP-AS1 enhances cell proliferation and metastasis in colorectal cancer by regulating miR-193a-5p/SENP1

BACKGROUND

Accumulating evidences have shown that long noncoding RNAs (lncRNAs) play key roles in many diseases, including cancer. Several studies reported that MCM3AP antisense RNA 1 (MCM3AP-AS1) was associated with the tumorigenesis and progression. However, the specific function and mechanism of MCM3AP-AS1 in colorectal cancer (CRC) have not been fully understood.

METHODS

The expression of MCM3AP-AS1 was detected by quantitative reverse transcription PCR (RT-qPCR) in CRC tissues and matched noncancerous tissues (NCTs). CCK-8 assay, colony formation assay, transwell assay, xenograft and lung metastasis mouse models were used to examine the tumor-promoting function of MCM3AP-AS1 in vitro and in vivo. The binding relationship between MCM3AP-AS1, miR-193a-5p and sentrin-specific peptidase 1 (SENP1) were screened and identified by databases, RT-qPCR, dual luciferase reporter assay and western blot.

RESULTS

In the present study, we got that the expression of MCM3AP-AS1 was higher in CRC tissues than in paired NCTs, and increased MCM3AP-AS1 expression was associated with adverse outcomes in CRC patients. Functional experiments in vitro revealed that silencing of MCM3AP-AS1 could inhibit the proliferation, colony formation, migratory, and invasive abilities of CRC cells. The mouse models of xenograft and lung metastasis further confirmed that in vivo silencing MCM3AP-AS1 could significantly inhibit the growth and metastasis of CRC. Further mechanism studies indicated that MCM3AP-AS1 could sponge miR-193a-5p and inhibit the activity of it. What is more, SENP1 was proved to be a novel target of miR-193a-5p and could be upregulated by MCM3AP-AS1. At last, we observed that SENP1 overexpression in CRC tissues was closely related to unfavorable prognosis.

CONCLUSION

Taken together, we identified in CRC the MCM3AP-AS1/miR-193a-5p/SENP1 regulatory axis, which affords a therapeutic possibility for CRC.

Role of LINC00152 in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) accounts for about 85% of all lung cancer cases. The pathogenesis of NSCLC involves complex gene networks that include different types of non-coding RNAs, such as long non-coding RNAs (lncRNAs). The role of lncRNAs in NSCLC is gaining an increasing interest as their function is being explored in various human cancers. Recently, a new oncogenic lncRNA, LINC00152 (cytoskeleton regulator RNA (CYTOR)), has been identified in different tumor types. In NSCLC, the high expression of LINC00152 in tumor tissue and peripheral blood samples has been shown to be associated with worse prognoses of NSCLC patients. Overexpression of LINC00152 has been confirmed to promote the proliferation, invasion, and migration of NSCLC cells in vitro, as well as increase tumor growth in vivo. This review discusses the role of LINC00152 in NSCLC.

MicroRNA-139 inhibits pancreatic-cancer carcinogenesis by suppressing RalB via the Ral/RAC/PI3K pathway

Micro-ribonucleic acids (miRNAs) are a class of conserved small non-coding RNAs (sncRNAs) that post-transcriptionally regulate their downstream target genes. Existing evidence indicates that abnormal expression of mRNAs results in the occurrence and development of pancreatic cancer (PC). In this study, we explored the potential role of miRNA-139 (miR-139) as a biomarker in the monitoring and treatment of PC. We demonstrated that expression of miR-139 was significantly downregulated in PC cells and tissues. In addition, both in vitro and in vivo experiments showed that miR-139 significantly inhibited the growth, migration, and invasion of PC cells. We carried out microarray analysis and transcriptome sequencing to find the potential target of miR-139 in PC cells, and the results showed that miR-139 targeted Ras-like proto-oncogene B (RalB). Luciferase reporter experiments verified that high level of RalB could reverse the proliferation and invasion of PC cells overexpressing miR-139. Using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, we found that miR-139 likely affected PC cell cycle by targeting RalB via the Ral/protein kinase B (Akt) serine/threonine kinase 1 (RAC)/phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway, thus affecting cell proliferation. This presumption was further confirmed in our in vitro and in vivo experiments. Our examination of PC tissues suggested that the expression of miR-139 was negatively correlated with that of RalB. Taken together, our results implied that miR-139 could suppress tumor growth and metastasis in PC by targeting RalB, revealing the potential role of miR-139 as a biomarker for the monitoring and treatment of PC.

LINC00152 upregulates ZEB1 expression and enhances epithelial-mesenchymal transition and oxaliplatin resistance in esophageal cancer by interacting with EZH2

BACKGROUND

Expression of the long non-coding mRNA LINC00152 has been reported to correlate with cancer cell resistance to oxaliplatin (L-OHP). However, little is known regarding the molecular mechanism of LINC00152 in esophageal cancer (EC). Hence, we intended to characterize the role of LINC00152 in EC, with a special focus on epithelial-mesenchymal transition (EMT) and L-OHP resistance.

METHODS

We collected EC tissues and identified EC cell lines with higher L-OHP resistance, and then characterized expression patterns of LINC00152, Zeste Homologue 2 (EZH2), Zinc finger e-box binding homeobox (ZEB1) and EMT-related genes using RT-qPCR and Western blot analysis. Furthermore, their functional significance was identified by gain and loss-of-function experiments. The relationship among LINC00152, EZH2 and ZEB1 was examined using RIP, RNA pull-down and ChIP assays. Additionally, resistance of EC cells to L-OHP was reflected by CCK-8 assay to detect cell viability. Animal experiments were also conducted to detect the effects of the LINC00152/EZH2/ZEB1 on EMT and L-OHP resistance.

RESULTS

LINC00152, EZH2 and ZEB1 were highly expressed in EC tissues and Kyse-150/TE-1 cells. As revealed by assays in vitro and in vivo, LINC00152 positively regulated ZEB1 expression through interaction with EZH2 to enhance EMT and L-OHP resistance in EC cells. In contrast, silencing of LINC00152 contributed to attenuated EMT and drug resistance of EC cells to L-OHP.

CONCLUSIONS

Our study demonstrates that LINC00152/EZH2/ZEB1 axis can regulate EMT and resistance of EC cells to L-OHP, thus presenting a potential therapeutic target for EC treatment.

Long intergenic non-coding RNA Linc00485 promotes lung cancer progression by modulating miR-298/c-Myc axis

Long non‐coding RNAs (lncRNAs), which are non‐protein‐coding transcripts, are emerging as novel biomarkers for cancer diagnosis. Their dysregulation is increasingly recognized to contribute to the development and progression of human cancers, including lung cancer. Linc00485 is a newly discovered cancer‐related lncRNA; however, little is known about its role in lung cancer progression. In this study, we found that the expression of Linc00485 was significantly increased in human lung cancer tissue and associated with malignant phenotypes, including tumour‐node‐metastasis (TNM) stage, metastasis and relapse. Furthermore, the proliferative, migratory and invasive abilities of lung cancer cells in vitro were significantly enhanced by overexpression of Linc00485 but inhibited by its silencing. Mechanistically, Linc00485 regulated the expression of c‐Myc by directly binding to miR‐298; the effects of Linc00485 overexpression could be significantly reversed by a c‐Myc inhibitor or small interfering RNA. Xenotransplantation experiments showed that Linc00485 silencing significantly weakened the proliferation potential of A549 cells in vivo. Overall, these findings indicate that Linc00485 overexpression down‐regulates miR‐298, resulting in the up‐regulation of c‐Myc and thereby promoting the development of lung cancer.

Long noncoding RNA RP11-757G1.5 sponges miR-139-5p and upregulates YAP1 thereby promoting the proliferation and liver, spleen metastasis of colorectal cancer

BACKGROUND

Accumulating evidence indicates that long non-coding RNAs (lncRNAs) acting as crucial regulators in tumorigenesis. However, its biological functions of lncRNAs in colorectal cancer (CRC) have not been systematically clarified.

METHODS

An unbiased screening was performed to identify disregulated lncRNAs revealed to be implicated in CRC carcinogenesis according to an online-available data dataset. In situ hybridization (ISH), RT-qPCR and RNA fluorescence in situ hybridization (RNA-FISH) were applied to detect RP11-757G1.5 expression in CRC tissues and cell lines. The associations of RP11-757G1.5 with clinicopathological characteristics were analyzed. Their effects on prognosis were analyzed by the Kaplan-Meier analysis, Log-rank test, Univariate and Multivariate Cox regression analysis. The potential biological function of RP11-757G1.5 in CRC was investigated by Colony formation, Edu cell proliferation, Flow cytometry, Wound healing and Transwell assays. Bioinformatics binding site analysis, Luciferase reporter assay, Ago2 immunoprecipitation assays, RNA pull-down assay, RT-qPCR and Western blotting were utilized to demonstrate the mechanism of RP11-757G1.5 acts as a molecular sponge of miR-139-5p to regulate the expression of YAP1. Finally, we further explore the potential role of RP11-757G1.5 in CRC orthotopic xenografts in vivo.

RESULTS

We discovered a novel oncogenic lncRNA RP11-757G1.5, that was overexpressed in CRC tissues, especially in aggressive cases. Moreover, up-regulation of RP11-757G1.5 strongly correlated with poor clinical outcomes of patients with CRC. Functional analyses revealed that RP11-757G1.5 promoted cell proliferation in vitro and in vivo. Furthermore, RP11-757G1.5 stimulated cell migration and invasion in vitro and in vivo. Mechanistic studies illustrated that RP11-757G1.5 regulated the expression of YAP1 through sponging miR-139-5p and inhibiting its activity thereby promoting CRC progression and development.

CONCLUSIONS

Altogether, these results reveal a novel RP11-757G1.5/miR-139-5p/YAP1 regulatory axis that participates in CRC carcinogenesis and progression.