Long noncoding RNA AOC4P regulates tumor cell proliferation and invasion by epithelial-mesenchymal transition in gastric cancer

Decoding the regulatory landscape of lncRNAs as potential diagnostic and prognostic biomarkers for gastric and colorectal cancers

Colorectal cancer (CRC) and gastric cancer (GC) are major contributors to cancer-related mortality worldwide. Despite advancements in understanding molecular mechanisms and improved drug treatments, the overall survival rate for patients remains unsatisfactory. Metastasis and drug resistance are major challenges contributing to the high mortality rate in both CRC and GC. Recent research has shed light on the role of long noncoding RNAs (lncRNAs) in the development and progression of these cancers. LncRNAs regulate gene expression through various mechanisms, including epigenetic modifications and interactions with microRNAs (miRNAs) and proteins. They can serve as miRNA precursors or pseudogenes, modulating gene expression at transcriptional and post-transcriptional levels. Additionally, circulating lncRNAs have emerged as non-invasive biomarkers for the diagnosis, prognosis, and prediction of drug therapy response in CRC and GC. This review explores the intricate relationship between lncRNAs and CRC/GC, encompassing their roles in cancer development, progression, and chemoresistance. Furthermore, it discusses the potential of lncRNAs as therapeutic targets in these malignancies. The interplay between lncRNAs, miRNAs, and tumor microenvironment is also highlighted, emphasizing their impact on the complexity of cancer biology. Understanding the regulatory landscape and molecular mechanisms governed by lncRNAs in CRC and GC is crucial for the development of effective diagnostic and prognostic biomarkers, as well as novel therapeutic strategies. This review provides a comprehensive overview of the current knowledge and paves the way for further exploration of lncRNAs as key players in the management of CRC and GC.

LncRNA AOC4P impacts the differentiation of macrophages and T-lymphocyte by regulating the NF-κB pathways of KGN cells: Potential pathogenesis of polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a multifactorial endocrine disease, which is an important cause of female infertility worldwide. PCOS patients are in a state of chronic low-grade inflammation, and immune imbalance is considered as a potential cause of its pathogenesis.

METHODS

The expression of AOC4P in PCOS and normal ovarian granulosa cells (GCs) was detected by real-time quantitative PCR. KGN cells were induced by dihydrotestosterone at 500 ng/mL to construct the PCOS model. After lentivirus-infected, KGN cells were constructed with AOC4P overexpression cell lines, the proliferation and apoptosis levels of KGN cells in AOC4P and NC groups were detected. Human monocyte cell line (THP-1)-derived macrophages and peripheral blood mononuclear cells (PBMC) were co-cultured with KGN cells for 48 h, respectively, and the differentiation of macrophages and CD4+ T cells were detected by flow cytometry.

RESULTS

Decreased AOC4P expression was found in PCOS patients. After constructing the PCOS cell model, we observed that overexpression of AOC4P promoted KGN cell proliferation and inhibited apoptosis. After co-culture with AOC4P overexpressed KGN cells, M1 macrophages decreased, M2 macrophages increased, T helper cells type 1 (Th1)/Th2 ratio increased, and regulatory T cell (Treg) cells increased. Finally, we found that AOC4P inhibited the activation of the nuclear factor κ B (NF-κB) pathway in KGN cells.

CONCLUSIONS

In this study, we found that AOC4P regulated the NF-κB signaling pathway by inhibiting the phosphorylation of P65, thereby affecting the proliferation and apoptosis of GCs, altering the differentiation of macrophages and T cells, thus contributing to the pathogenesis of PCOS.

Epithelial-mesenchymal transition-related long noncoding RNAs in gastric carcinoma

As an evolutionarily phenotypic conversion program, the epithelial-mesenchymal transition (EMT) has been implicated in tumour deterioration and has facilitated the metastatic ability of cancer cells via enhancing migration and invasion. Gastric cancer (GC) remains a frequently diagnosed non-skin malignancy globally. Most GC-associated mortality can be attributed to metastasis. Recent studies have shown that EMT-related long non-coding RNAs (lncRNAs) play a critical role in GC progression and GC cell motility. In addition, lncRNAs are associated with EMT-related transcription factors and signalling pathways. In the present review, we comprehensively described the EMT-inducing lncRNA molecular mechanisms and functional perspectives of EMT-inducing lncRNAs in GC progression. Taken together, the statements of this review provided a clinical implementation in identifying lncRNAs as potential therapeutic targets for advanced GC.

Identification of genomic instability related lncRNA signature with prognostic value and its role in cancer immunotherapy in pancreatic cancer

Background: Increasing evidence suggested the critical roles of lncRNAs in the maintenance of genomic stability. However, the identification of genomic instability-related lncRNA signature (GILncSig) and its role in pancreatic cancer (PC) remains largely unexplored.

Methods: In the present study, a systematic analysis of lncRNA expression profiles and somatic mutation profiles was performed in PC patients from The Cancer Genome Atlas (TCGA). We then develop a risk score model to describe the characteristics of the model and verify its prediction accuracy. ESTIMATE algorithm, single-sample gene set enrichment analysis (ssGSEA), and CIBERSORT analysis were employed to reveal the correlation between tumor immune microenvironment, immune infiltration, immune checkpoint blockade (ICB) therapy, and GILncSig in PC.

Results: We identified 206 GILnc, of which five were screened to develop a prognostic GInLncSig model. Multivariate Cox regression analysis and stratified analysis revealed that the prognostic value of the GILncSig was independent of other clinical variables. Receiver operating characteristic (ROC) analysis suggested that GILncSig is better than the existing lncRNA-related signatures in predicting survival. Additionally, the prognostic performance of the GILncSig was also found to be favorable in patients carrying wild-type KRAS, TP53, and SMAD4. Besides, a nomogram exhibited appreciable reliability for clinical application in predicting the prognosis of patients. Finally, the relationship between the GInLncSig model and the immune landscape in PC reflected its application value in clinical immunotherapy.

Conclusion: In summary, the GILncSig identified by us may serve as novel prognostic biomarkers, and could have a crucial role in immunotherapy decisions for PC patients.

LncRNA DLEU2 silencing impedes the migration, invasion and EMT in gastric cancer cell by suppressing PI3K/AKT signaling pathway

Context: The high expression of long non-coding RNA deleted in lymphocytic leukaemia 2 (lncRNA DLEU2) has been confirmed in gastric cancer (GC).Objective: However, the detailed mechanism concerning its involvement in GC remained unclear, which we aimed to explore in this study.Materials and methods: LncRNA DLEU2 expression in GC was estimated by bioinformatic analysis, and the relationship between the expression of DLEU2 and the clinicopathological characteristics of patients with GC was performed. qRT-PCR was employed to detect the expression of lncRNA DLEU2 and confirm the transfection efficiency following the knockdown or overexpression of DLEU2. Functional assays, including CCK-8, flow cytometry, scratching test and Transwell assays, were used to determine the role of DLEU2 in tumor phenotypes. The effects of DLEU2 on the PI3K/Akt pathway were detected by western blot. For elucidating the functions of DLEU2/PI3K/Akt axis in GC, we inhibited the PI3K/Akt pathway in rescue experiments, and evaluated the expression levels of epithelial-mesenchymal transition (EMT)-related proteins by western blot.Results: The expression of DLEU2 was aberrantly up-regulated in GC tissues and cells, which was correlated with the degree of tumor differentiation, cancer antigen 19-9 (CA19-9) and Lauren histologic classification of patients with GC. Silencing of DLEU2 induced apoptosis, attenuated viability, migration and invasion as well as inhibited the PI3K/Akt signaling pathway in GC cells. Mechanistically, the DLEU2/PI3K/Akt axis promoted the progression of GC and the EMT by down-regulating the expression of E-Cadherin and up-regulating those of N-Cadherin and Vimentin.Discussion and conclusions: LncRNA DLEU2 promoted the migration, invasion and EMT in GC by activating the PI3K/Akt pathway.

Gastric cancer: An epigenetic view

Gastric cancer (GC) poses a serious threat worldwide with unfavorable prognosis mainly due to late diagnosis and limited therapies. Therefore, precise molecular classification and search for potential targets are required for diagnosis and treatment, as GC is complicated and heterogeneous in nature. Accumulating evidence indicates that epigenetics plays a vital role in gastric carcinogenesis and progression, including histone modifications, DNA methylation and non-coding RNAs. Epigenetic biomarkers and drugs are currently under intensive evaluations to ensure efficient clinical utility in GC. In this review, key epigenetic alterations and related functions and mechanisms are summarized in GC. We focus on integration of existing epigenetic findings in GC for the bench-to-bedside translation of some pivotal epigenetic alterations into clinical practice and also describe the vacant field waiting for investigation.

Role of LncRNAs in the Epithelial-Mesenchymal Transition in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a type of primary liver cancer with a high incidence and mortality rate. HCC develops insidiously, and most newly diagnosed cases are in the middle and advanced stages. The epithelial-mesenchymal transition (EMT) is a vital mechanism underlying metastasis in patients with advanced HCC. EMT is a multistep and complex procedure. The promotion and inhibition of EMT directly affect the migration and invasion of HCC. LncRNAs are involved in the epigenetic modification of genes, regulation of gene transcription, and posttranslational modification of proteins. LncRNAs also play important roles in regulating EMT progression in HCC and are promising biomarkers and therapeutic targets. This review focused on summarizing the mechanism by which lncRNAs regulate EMT in HCC. In particular, lncRNAs were reported to primarily act as RNA sponges, and the regulation of EMT involves major signaling pathways. Finally, we reviewed the mechanisms by which lncRNAs are involved in drug resistance and discussed the clinical prospects and potential challenges of utilizing lncRNAs to treat HCC.

Improved understanding of gastrointestinal stromal tumors biology as a step for developing new diagnostic and therapeutic schemes

A gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the human gastrointestinal tract, with an estimated incidence of 10-15 per 1 million per year. While preparing holistic care for patients with GIST diagnosis, scientists might face several difficulties - insufficient risk stratification, acquired or secondary resistance to imatinib, or the need for an exceptional therapy method associated with wild-type tumors. This review summarizes recent advances associated with GIST biology that might enhance diagnostic and therapeutic strategies. New molecules might be incorporated into risk stratification schemes due to their proven association with outcomes; however, further research is required. Therapies based on the significant role of angiogenesis, immunology, and neural origin in the GIST biology could become a valuable enhancement of currently implemented treatment schemes. Generating miRNA networks that would predict miRNA regulatory functions is a promising approach that might help in better selection of potential biomarkers and therapeutical targets in cancer, including GISTs.

Knockdown of TPT1-AS1 inhibits cell proliferation, cell cycle G1/S transition, and epithelial-mesenchymal transition in gastric cancer

Long non-coding RNAs are considered to be critical regulators of tumor progression. Tumor protein translationally controlled 1 antisense RNA 1 (TPT1-AS1) was shown to have an oncogenic role in cervical and ovarian cancer. The clinical significance and biological function of TPT1-AS1 in gastric cancer (GC) are not clear. In this study, we analyzed the expression of TPT1-AS1 in GC tissues and cell lines and performed functional and mechanistic analysis of TPT1-AS1 effects on GC cell proliferation, migration, and invasion. TPT1-AS1 expression was determined in 76 pairs of GC tissues vs. matched adjacent normal tissues and in four GC cell lines (SGC-7901, AGS, BGC-823, and MGC-803) vs. GES-1 cell line by quantitative reverse transcription PCR. SGC-7901 and MGC-803 cells were transfected with small interfering RNA or scrambled negative control, and cell proliferation, colony formation, migration, invasion and cell cycle assays were performed. The expression of proteins involved in cell cycle progression and epithelial-mesenchymal transition was analyzed by Western blot. TPT1-AS1 expression was significantly higher in GC tissues and cell lines compared to controls. The overexpression of TPT1-AS1 was significantly correlated with TNM stage and lymph node metastasis, and it was associated with worse prognosis of GC patients according to the Kaplan-Meier survival analysis and Cox proportional hazard regression analysis. The knockdown of TPT1-AS1 significantly inhibited proliferation, cell cycle G1/S transition, migration, and invasion of SGC-7901 and MGC-803 cells. Moreover, TPT1-AS1 knockdown downregulated the expression of cyclin-dependent kinase (CDK) 4, cyclin D1, and vimentin and upregulated the expression of p21 and E-cadherin. Our findings suggest that TPT1-AS1 may be a promising therapeutic target in GC.

Competing Endogenous RNA Networks in the Epithelial to Mesenchymal Transition in Diffuse-Type of Gastric Cancer

Simple Summary

The diffuse-type of gastric cancer is associated with epithelial to mesenchymal transition. Loss of E-cadherin expression is the hallmark of this process and is largely due to the upregulation of the transcription factors ZEB1/2, Snail, Slug, and Twist1/2. However, miRNA and lncRNAs can also participate through these transcription factors which directly target E-cadherin. The competing endogenous RNA (ceRNA) network hypothesis state that lncRNA can sponge the miRNA pool that targets these transcripts. Based on the lack of said networks in the epithelial to mesenchymal transition, we performed a prediction analysis that resulted in novel ceRNA networks which will expand our knowledge of the molecular basis of the diffuse-type of gastric cancer.

Abstract

The diffuse-type of gastric cancer (DGC), molecularly associated with epithelial to mesenchymal transition (EMT), is increasing in incidence. Loss of E-cadherin expression is the hallmark of the EMT process and is largely due to the upregulation of the EMT-inducing transcription factors ZEB1/2, Snail, Slug, and Twist1/2. However, ncRNA, such as miRNA and lncRNAs, can also participate in the EMT process through the direct targeting of E-cadherin and other EMT-inducing transcription factors. Additionally, lncRNA can sponge the miRNA pool that targets these transcripts through competing endogenous RNA (ceRNA) networks. In this review, we focus on the role of ncRNA in the direct deregulation of E-cadherin, as well as EMT-inducing transcription factors. Based on the relevance of the ceRNA network hypothesis, and the lack of said networks in EMT, we performed a prediction analysis for all miRNAs and lncRNAs that target E-cadherin, as well as EMT-inducing transcription factors. This analysis resulted in novel predicted ceRNA networks for E-cadherin and EMT-inducing transcription factors (EMT-TFs), as well as the expansion of the molecular basis of the DGC.

Deficiency of pseudogene UPAT leads to hepatocellular carcinoma progression and forms a positive feedback loop with ZEB1

Hepatocellular carcinoma (HCC) is a common disease worldwide. Accumulating reports have evidenced the internal connection between epithelial‐mesenchymal transition (EMT) and cancer stem cells (CSCs), as well as their significance in metastasis and post–operative recurrence. In this study, we investigated an interesting ubiquitin‐proteasome pathway associated pseudogene of AOC4, also known as UPAT, and showed that it was downregulated in 39.78% (37/93) of patients with hepatitis B virus (HBV)‐related HCC. Downregulation of UPAT was associated with multiple worse clinicopathological parameters, as well as decreased recurrence‐free survival (RFS). In vitro and in vivo assays found that overexpression of UPAT significantly suppressed cellular migration, invasion, EMT processes, and CSC properties. Mechanistic studies showed that UPAT promoted ZEB1 degradation via a ubiquitin‐proteasome pathway and, in contrast, ZEB1 transcriptionally suppressed UPAT by binding to multiple E‐box (CACCTG) elements in the promoter region. Moreover, UPAT was negatively correlated with ZEB1 protein in HCC tissues, their combined expression discriminated RFS outcomes for patients with HBV‐related HCC. These data on the UPAT‐ZEB1 circuit‐mediated pathway will further knowledge on EMT and CSCs, and may help to develop novel therapeutic approaches for the prevention of HCC metastasis.

Expression and clinicopathological significance of AOC4P, PRNCR1, and PCAT1 lncRNAs in breast cancer

Long none coding RNAs (lncRNAs) AOC4P, PRNCR1, and PCAT-1 are dysregulated in various types of malignancies. However, their expression and clinicopathological significances are uncertain in breast cancer (BC). Quantitative real-time polymerase chain reaction (RT- qPCR) was used to measure the expression levels of the selected lncRNAs in tumor tissues obtained from 50 BC patients compared to the normal adjacent tissues (NATs) and 50 clinically healthy normal tissues. Our results revealed a significant downregulation of AOC4P, however, upregulated PRNCR1 and PCAT1 were found in tumor tissues compared to NATs and clinically healthy normal tissues (P < 0.05). Interestingly, remarkable decreased expression of AOC4P was observed in NATs than clinically healthy normal tissues. Dysregulation of the lncRNAs was correlated with worse outcomes of patients. Furthermore, our data showed that the altered expression levels of lncRNAs AOC4P, PRNCR1, and PCAT1 might be occurred through the function of demographic and reproductive variables. Taken together, the altered regulation of AOC4P, PRNCR1, and PCAT1 may highlight their crucial roles in BC development and pathogenesis. Our findings also proposed demographic and reproductive variables as risk factors in BC through the possible influence on the expression of the studied lncRNAs. Nevertheless, further explorations are required to elucidate the more detailed functions of these lncRNAs in BC.

Comprehensive analysis of long non‑coding RNA using an associated competitive endogenous RNA network in Wilms tumor

Wilms tumor (WT) is the most common malignant renal neoplasm in children; however, the underlying molecular mechanisms are not well understood. According to the competing endogenous RNA (ceRNA) theory, long non-coding RNAs (lncRNAs) can regulate the expression of target genes by adsorbing microRNAs (miRNAs/miRs). However, the role of lncRNAs in WT has not been fully elucidated. The aim of the present study was to construct a ceRNA network to identify the potential lncRNAs involved in WT. The expression profiles of lncRNAs, miRNAs and mRNAs in 120 WT and six normal tissues were obtained from the Therapeutically Applicable Research to Generate Effective Treatments database. A total of 442 lncRNAs, 214 miRNAs and 4,912 mRNAs were identified as differentially expressed in WT and were enriched in 472 Gene Ontology terms (355 biological processes, 89 cellular components and 29 molecular functions) and 18 Kyoto Encyclopedia of Genes and Genomes pathways. A lncRNA-miRNA-mRNA ceRNA network of WT consisting of with 32 lncRNAs, 14 miRNAs and 158 mRNAs was constructed, based on the bioinformatics analysis of the miR target prediction database and the miRNAcode, miRTarBase and TargetScan databases. Subsequently, three lncRNAs, three miRNAs and 17 mRNAs, which had a significant effect on the overall survival rate of patients with WT, were identified based on the survival analysis. The three lncRNAs were also differentially expressed in the late and early stages of WT and were validated using the GSE66405 dataset obtained from the Gene Expression Omnibus database. In conclusion, the present study generated a specific lncRNA-related ceRNA network of WT, which may provide a novel perspective on the molecular mechanisms underlying the progression and prognosis of the disease.

Long non-coding RNA AOC4P suppresses epithelial ovarian cancer metastasis by regulating epithelial-mesenchymal transition

Objective

Currently, the function and mechanisms of long non-coding RNAs (lncRNAs) involved in the metastasis of epithelial ovarian cancer (EOC), especially those of the lncRNAs participated in the epithelial-mesenchymal transition (EMT) process, remains largely unknown. Here, we focused on a lncRNA named AOC4P and analysed its role in EOC.

Materials and methods

The expression of AOC4P gene was examined with quantitative real-time quantitative PCR (qRT-PCR). The cell migration and invasion were detected by Transwell and scratch assays. The in vivo metastatic activity was evaluated by intraperitoneal metastasis model. The downstream genes were investigated by a tumour EMT real-time polymerase chain reaction (RT-PCR) array, and validated by qRT-PCR and Western blot.

Results

The results showed that AOC4P expression levels were decreased in EOC tissues and cell lines, and that the under-expression of AOC4P was positively correlated with FIGO stage and lymph node metastasis. Furthermore, the knockdown of AOC4P expression in poorly metastatic EOC cell lines remarkably facilitated cell migration/invasion while the overexpression of AOC4P in highly metastatic EOC cell lines reduced the metastatic ability of these cells in vitro. Consistently, the anti-metastatic role of AOC4P in vivo was also verified by bioluminescence imaging and tumour dissection. Mechanistically, the anti-metastatic effect of AOC4P in EOC was partially mediated by the EMT process accompanied by the alterations in MMP9 and COL1A2 expression.

Conclusion

These data highlight that AOC4P plays a critical role in EOC invasion/metastasis and could function as a novel and effective target for the lncRNA-based anti-metastatic clinical management of EOC.

Up-regulation of long non-coding RNA AWPPH inhibits proliferation and invasion of gastric cancer cells via miR-203a/DKK2 axis

AWPPH is a newly discovered long non-coding RNA (lncRNA). However, the expression and function of AWPPH in gastric cancer (GC) have not yet been clarified. This study tries to assess the expression and biological roles of AWPPH in GC and the underlying mechanism. The expression of lncRNA AWPPH was evaluated in GC tissues and adjacent normal tissues from 40 patients. Cell Counting Kit-8 (CCK8) and transwell assays were applied to assess cell proliferation and invasion capabilities. Bioinformatics tool was employed to predict AWPPH's sponging miRNA, while luciferase reporter assays were used to verify the target. LncRNA AWPPH was remarkably downregulated in GC and associated with metastasis. CCK8 and transwell assays proved that AWPPH inhibited cell proliferation and invasion in GC cells. MiR-203a was a predicted and further verified target of AWPPH. DKK2 was verified as a direct target of miR-203a. Upregulation of miR-203a attenuated the repressive effects of AWPPH on GC cell proliferation and invasion. AWPPH inhibited GC cell proliferation and invasion via miR-203a/DKK2 axis. This finding might provide new insight for the potential therapeutic strategies for GC in the future.

Identification and potential mechanisms of a 4-lncRNA signature that predicts prognosis in patients with laryngeal cancer

Purpose

This study aimed to describe the use of a novel 4-lncRNA signature to predict prognosis in patients with laryngeal cancer and to explore its possible mechanisms.

Methods

We identified lncRNAs that were differentially expressed between 111 tumor tissue samples and 12 matched normal tissue samples from The Cancer Genome Atlas Database (TCGA). We used Cox regression analysis to identify lncRNAs that were correlated with prognosis. A 4-lncRNA signature was developed to predict the prognosis of patients with laryngeal cancer. The receiver operating characteristic (ROC) curves and area under the curve (AUC) were used to verify the validity of this Cox regression model, and an independent prognosis analysis was used to confirm that the 4-lncRNA signature was an independent prognostic factor. Furthermore, the function of these lncRNAs was inferred using related gene prediction and Gene ontology (GO) enrichment analysis in order to clarify the possible mechanisms underlying their predictive ability.

Results

In total, 214 differentially expressed lncRNAs were identified, and a 4-lncRNA signature was constructed using Cox survival analysis. The risk coefficients in the multivariate Cox analysis revealed that LINC02154 and MNX1-AS1 are risk factors for laryngeal cancer, whereas MYHAS and LINC01281 appear to be protective factors. The results of a functional annotation analysis suggested that the mechanisms by which these lncRNAs influence prognosis in laryngeal cancer may involve the extracellular exosome, the Notch signaling pathway, voltage-gated calcium channels, and the Wnt signaling pathway.

Conclusion

We identified a novel 4-lncRNA signature that can predict the prognosis of patients with laryngeal cancer and that may influence the prognosis of laryngeal cancer by regulating immunity, tumor apoptosis, metastasis, invasion, and other characteristics through the Notch signaling pathway, voltage-gated calcium channels, and the Wnt signaling pathway.

Electronic supplementary material

The online version of this article (10.1186/s40246-019-0230-6) contains supplementary material, which is available to authorized users.