Correlation between LncRNA-LINC00659 and clinical prognosis in gastric cancer and study on its biological mechanism

Identification and validation of tryptophan metabolism-related lncRNAs in lung adenocarcinoma prognosis and immune response

BACKGROUND

Tryptophan (Trp) is an essential amino acid. Increasing evidence suggests that tryptophan metabolism plays a complex role in immune escape from Lung adenocarcinoma (LUAD). However, the role of long non-coding RNAs (lncRNAs) in tryptophan metabolism remains to be investigated.

METHODS

This study uses The Cancer Genome Atlas (TCGA)-LUAD dataset as the training cohort, and several datasets from the Gene Expression Omnibus (GEO) database are merged into the validation cohort. Genes related to tryptophan metabolism were identified from the Molecular Signatures Database (MSigDB) database and further screened for lncRNAs with Trp-related expression. Subsequently, a prognostic signature of lncRNAs related to tryptophan metabolism was constructed using Cox regression analysis, (Least absolute shrinkage and selection operator regression) and LASSO analysis. The predictive performance of this risk score was validated by Kaplan-Meier (KM) survival analysis, (receiver operating characteristic) ROC curves, and nomograms. We also explored the differences in immune cell infiltration, immune cell function, tumor mutational load (TMB), tumor immune dysfunction and exclusion (TIDE), and anticancer drug sensitivity between high- and low-risk groups. Finally, we used real-time fluorescence quantitative PCR, CCK-8, colony formation, wound healing, transwell, flow cytometry, and nude mouse xenotransplantation models to elucidate the role of ZNF8-ERVK3-1 in LUAD.

RESULTS

We constructed 16 tryptophan metabolism-associated lncRNA prognostic models in LUAD patients. The risk score could be used as an independent prognostic indicator for the prognosis of LUAD patients. Kaplan-Meier survival analysis, ROC curves, and risk maps validated the prognostic value of the risk score. The high-risk and low-risk groups showed significant differences in phenotypes, such as the percentage of immune cell infiltration, immune cell function, gene mutation frequency, and anticancer drug sensitivity. In addition, patients with high-risk scores had higher TMB and TIDE scores compared to patients with low-risk scores. Finally, we found that ZNF8-ERVK3-1 was highly expressed in LUAD tissues and cell lines. A series of in vitro experiments showed that knockdown of ZNF8-ERVK3-1 inhibited cell proliferation, migration, and invasion, leading to cell cycle arrest in the G0/G1 phase and increased apoptosis. In vivo experiments with xenografts have shown that knocking down ZNF8-ERVK3-1 can significantly inhibit tumor size and tumor proliferation.

CONCLUSION

We constructed a new prognostic model for tryptophan metabolism-related lncRNA. The risk score was closely associated with common clinical features such as immune cell infiltration, immune-related function, TMB, and anticancer drug sensitivity. Knockdown of ZNF8-ERVK3-1 inhibited LUAD cell proliferation, migration, invasion, and G0/G1 phase blockade and promoted apoptosis.

Long non-coding RNA linc00659 promotes tumour progression by regulating FZD6/Wnt/β-catenin signalling pathway in colorectal cancer via m6A reader IGF2BP1

BACKGROUND

Abnormal N6-methyladenosine (m6A) modification has become a driving factor in tumour development and progression. The linc00659 is abnormally highly expressed in digestive tract tumours and promotes cancer progression, but there is little research on the mechanism of linc00659 and m6A.

METHODS

The expression of linc00659 in colorectal cancer (CRC) tissues and cells was assessed by a quantitative real-time PCR. The proliferative capacity of CRC cells was determined by colony formation, Cell Counting Kit-8 and 5-ethynyl-2 deoxyuridine assays, and the migratory capacity of CRC was determined by wound healing and transwell assays and tube formation. In vivo, a xenograft tumour model was used to detect the effect of linc00659 on tumour growth. The Wnt/β-catenin signalling pathway and related protein expression levels were measured by western blotting. The binding of linc00659 to insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) was assessed by RNA pull-down and an immunoprecipitation assay. The effect of IGF2BP1 on FZD6 was detected by an RNA stability assay.

RESULTS

The expression of linc00659 was abnormally elevated in CRC tissues and cells compared to normal colonic tissues and cells. We confirm that linc00659 promotes the growth of CRC cells both in vivo and in vitro. Mechanistically, linc00659 binds to IGF2BP1 and specifically enhances its activity to stabilize the target gene FZD6. Therefore, linc00659 and IGF2BP1 activate the Wnt/β-catenin signalling pathway, promoting cell proliferation in CRC.

CONCLUSIONS

Our results show that linc00659 and IGF2BP1 cooperate to promote the stability of the target FZD6 mRNA, thereby facilitating CRC progression, which may represent a potential diagnostic, prognostic and therapeutic target for CRC.

LncRNA SPRY4‑IT1 is upregulated and promotes the proliferation of prostate cancer cells under hypoxia in vitro

The incidence and mortality rate of prostate cancer are among the highest for all cancers worldwide; this disease has a high cancer mortality rate in males, following lung cancer. Sprouty4-intron 1 (SPRY4-IT1) has been shown to play a variety of roles in tumors. Our previous study demonstrated that SPRY4-IT1 sponges microRNA-101-3p to promote the proliferation and metastasis of bladder cancer cells by upregulating enhancer of zeste homolog 2 expression; however, the role of SPRY4-IT1 in prostate cancer has not been fully established. In the present study, the expression levels, effects and mechanism of action of SPRY4-IT1 were investigated in prostate cancer tissues and cell lines using reverse transcription-quantitative PCR, western blotting, Cell Counting Kit-8 and flow cytometry assays. The results indicated that SPRY4-IT1 expression was upregulated in prostate cancer tissues and cell lines. Furthermore, hypoxia increased the expression levels of SPRY4-IT1 in prostate cancer cells. Knockdown of SPRY4-IT1 expression led to S-phase arrest, decreased expression levels of the cell cycle-associated proteins CDK2 and cyclin D1. AKT phosphorylation was also reduced by SPRY4-IT1 knockdown. In summary, the findings indicate the elevation of SPRY4-IT1 expression in prostate cancer. Under hypoxic conditions in vitro, SPRY4-IT1 overexpression promoted prostate cancer cell proliferation via a mechanism involving regulation of the cell cycle and the PI3K/AKT signaling pathway. Therefore, it may provide a basis for the development of targeted therapies.

By modulating miR-525-5p/Bax axis, LINC00659 promotes vascular endothelial cell apoptosis

BACKGROUND

Deep vein thrombosis (DVT) is a vascular disease that has no effective treatment at present. Endothelial cells play a crucial role in the processes vasoconstriction, platelet activation, and blood coagulation and are an integral part of the vascular response to injury resulting in thrombus formation.

OBJECTIVE

The aim of this study was to investigate the roles and mechanisms of long noncoding RNA LINC00659 (LINC00659) in endothelial cells.

METHODS

The functions of LINC00659 and miR-525-5p on endothelial cells were explored by cell transfection assays, and the expression levels of LINC00659, miR-525-5p, and Bax in human umbilical vein endothelial cells (HUVECs) were assessed with reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR). Binding sites of LINC00659 and miR-525-5p were subsequently analyzed with bioinformatics software, and validated with dual-luciferase reporter gene assay. Effects of LINC00659 and miR-525-5p on proliferation and apoptosis of HUVECs were detected with MTT (3-(45)-dimethylthiahiazo (-z-y1)-35-di-phenytetrazoliumromide) assay and flow cytometry. RT-qPCR and western blot analysis were used to evaluate the mRNA and protein levels of apoptosis-related markers Bcl-2 and Bax in HUVECs.

RESULTS

LINC00659 directly targeted and negatively regulated miR-525-5p, and Bax was a target of miR-525-5p. Upregulation of LINC00659 could inhibit proliferation and promote apoptosis of HUVECs, while the silencing of LINC00659 could increase the viability of HUVECs and inhibit apoptosis via upregulating miR-525-5p. Further mechanistic studies revealed miR-525-5p could negatively regulate Bax in HUVECs, and increased the viability of HUVECs and inhibited apoptosis by downregulating Bax expression.

CONCLUSION

LINC00659 played an important role in DVT by regulating the apoptosis of vascular endothelial cells through regulating miR-525-5p/Bax axis.

TRIM50 Inhibits Proliferation and Metastasis of Gastric Cancer via Promoting β-Catenin Degradation

Background

Gastric cancer (GC) is a common malignancy with a poor prognosis. Tripartite motif-containing 50 (TRIM50) belongs to the TRIM family and is reported to be related to numerous cancers. This study aimed to investigate the function of TRIM50 in GC.

Methods

Three microarray datasets (GSE13911, GSE79973, and GSE19826) containing GC and adjacent nontumor tissues were used for bioinformatics analysis to screen GC-related genes and assess the associations between GC development and TRIM50 expression. Then, TRIM50 expression in GC cells was detected at mRNA and protein levels. After TRIM50 was knockdown or overexpressed, the effect of TRIM50 on the proliferation and metastasis of GC cells was analyzed using Cell Counting Kit-8 (CCK-8), flow cytometry, scratch, and Transwell assays. The interaction between TRIM50 and β-catenin was analyzed. The expression of cell cycle-, migration-, invasion-, and Wnt/β-catenin signaling pathway-related proteins was detected by Western blot. Furthermore, we measured the role of TRIM50 overexpression on tumor growth as well as the Wnt/β-catenin signaling pathway in vivo. In addition, XAV939 (a WNT/β-catenin signaling pathway inhibitor) was used to clarify the mechanism of TRIM50 on GC.

Results

Bioinformatics revealed that TRIM50 expression was decreased in GC samples and associated with GC development. In vitro study revealed that TRIM50 overexpression impeded the GC cell proliferation and metastasis, while TRIM50 knockdown presented the opposite results. In addition, TRIM50 interacted with β-catenin to induce the degradation of β-catenin. In in vivo assay, TRIM50 overexpression inhibited tumor growth and blocked the Wnt/β-catenin signaling pathway. In addition, TRIM50 knockdown-promoted cell proliferation and metastasis in GC cells were inverted by XAV939.

Conclusion

TRIM50 overexpression may inhibit cell proliferation and metastasis in GC via β-catenin degradation, indicating that TRIM50 could be a target for the treatment of GC.

Emerging role of exosomes in cancer progression and tumor microenvironment remodeling

Cancer is one of the leading causes of death worldwide, and the factors responsible for its progression need to be elucidated. Exosomes are structures with an average size of 100 nm that can transport proteins, lipids, and nucleic acids. This review focuses on the role of exosomes in cancer progression and therapy. We discuss how exosomes are able to modulate components of the tumor microenvironment and influence proliferation and migration rates of cancer cells. We also highlight that, depending on their cargo, exosomes can suppress or promote tumor cell progression and can enhance or reduce cancer cell response to radio- and chemo-therapies. In addition, we describe how exosomes can trigger chronic inflammation and lead to immune evasion and tumor progression by focusing on their ability to transfer non-coding RNAs between cells and modulate other molecular signaling pathways such as PTEN and PI3K/Akt in cancer. Subsequently, we discuss the use of exosomes as carriers of anti-tumor agents and genetic tools to control cancer progression. We then discuss the role of tumor-derived exosomes in carcinogenesis. Finally, we devote a section to the study of exosomes as diagnostic and prognostic tools in clinical courses that is important for the treatment of cancer patients. This review provides a comprehensive understanding of the role of exosomes in cancer therapy, focusing on their therapeutic value in cancer progression and remodeling of the tumor microenvironment.

LINC01857 promotes the proliferation, migration, and invasion of gastric cancer cells via regulating miR-4731-5p/HOXC6

The great importance of long non-coding RNAs (lncRNAs) in tumorigenesis has been acknowledged gradually. LINC01857 is previously reported to be highly expressed in gastric cancer (GC), while the regulatory mechanism of LINC01857 in gastric cancer is largely unknown. In this study, we detected high expression of LINC01857 from the gastric cancer microarray GSE109476. Additionally, LINC01857 expression is remarkably up-regulated in gastric cancer cell lines (AGS, MKN-45, HGC-27 and SGC-7901) compared to the normal gastric mucosal cell line GES-1. Functionally, LINC01857 knockdown suppressed the proliferation, migration, invasion, and epithelial-mesenchymal transformation (EMT) of GC cells, while LINC01857 overexpression promoted the proliferation, migration, invasion and EMT of GC cells. Furthermore, our data demonstrate that LINC01857 targeted miR-4731-5p and subsequently increased the expression of HOXC6 in GC. Rescue experiments showed that miR-4731-5p inhibition and HOXC6 overexpression could reverse the biological behavior of GC cells induced by LINC01857 knockdown. In conclusion, we demonstrated that LINC01857 sponged miR-4731-5p to promote the expression of HOXC6 and eventually acts as an oncogene in GC.

Interaction of ncRNA and Epigenetic Modifications in Gastric Cancer: Focus on Histone Modification

Gastric cancer has developed as a very common gastrointestinal tumors, with recent effective advancements in the diagnosis and treatment of early gastric cancer. However, the prognosis for gastric cancer remains poor. As a result, there is in sore need of better understanding the mechanisms of gastric cancer development and progression to improve existing diagnostic and treatment options. In recent years, epigenetics has been recognized as an important contributor on tumor progression. Epigenetic changes in cancer include chromatin remodeling, DNA methylation and histone modifications. An increasing number of studies demonstrated that noncoding RNAs (ncRNAs) are associated with epigenetic changes in gastric cancer. Herein, we describe the molecular interactions of histone modifications and ncRNAs in epigenetics. We focus on ncRNA-mediated histone modifications of gene expression associated with tumorigenesis and progression in gastric cancer. This molecular mechanism will contribute to our deeper understanding of gastric carcinogenesis and progression, thus providing innovations in gastric cancer diagnosis and treatment strategies.

MicroRNAs regulating SOX2 in cancer progression and therapy response

The proliferation, metastasis and therapy response of tumour cells are tightly regulated by interaction among various signalling networks. The microRNAs (miRNAs) can bind to 3'-UTR of mRNA and down-regulate expression of target gene. The miRNAs target various molecular pathways in regulating biological events such as apoptosis, differentiation, angiogenesis and migration. The aberrant expression of miRNAs occurs in cancers and they have both tumour-suppressor and tumour-promoting functions. On the contrary, SOX proteins are capable of binding to DNA and regulating gene expression. SOX2 is a well-known member of SOX family that its overexpression in different cancers to ensure progression and stemness. The present review focuses on modulatory impact of miRNAs on SOX2 in affecting growth, migration and therapy response of cancers. The lncRNAs and circRNAs can function as upstream mediators of miRNA/SOX2 axis in cancers. In addition, NF-κB, TNF-α and SOX17 are among other molecular pathways regulating miRNA/SOX2 axis in cancer. Noteworthy, anti-cancer compounds including bufalin and ovatodiolide are suggested to regulate miRNA/SOX2 axis in cancers. The translation of current findings to clinical course can pave the way to effective treatment of cancer patients and improve their prognosis.

The role of M6A modification in the regulation of tumor-related lncRNAs

N⁶-methyladenosine (m⁶A) is the most abundant modification in eukaryotic cells, and it regulates RNA transcription, processing, splicing, degradation, and translation. Long non-coding RNAs (lncRNAs), as transcriptional products with no or limited protein coding ability more than 200 nt in length, play an important role in epigenetic modification, mRNA transcription, splicing, stability, translation, and other biological functions. Extensive studies have shown that both m⁶A modification and lncRNAs are involved in the pathogenesis of various diseases, such as kinds of cancers, heart failure, Alzheimer’s disease, periodontitis, human abdominal aortic aneurysm, and obesity. To date, m⁶A modification has been identified as an important biological function in enrichment and regulation of lncRNAs. In this review, we summarize the role of m⁶A modification in the regulation and function of tumor-related lncRNAs. Moreover, we discuss the potential applications and possible future directions in the field.

Transcriptome Profiling Reveals the Endogenous Sponging Role of LINC00659 and UST-AS1 in High-Altitude Induced Thrombosis

BACKGROUND

 The pathophysiology of deep vein thrombosis (DVT) is considered as multifactorial, where thrombus formation is an interplay of genetic and acquired risk factors. Little is known about the expression profile and roles of long noncoding RNAs (lncRNAs) in human subjects developing DVT at high altitude.

METHODS

 Using RNAseQ, we compared peripheral blood mRNA and lncRNA expression profile in human high-altitude DVT (HA-DVT) patients with high-altitude control subjects. We used DESeq to identify differentially expressed (DE) genes. We annotated the lncRNAs using NONCODE 3.0 database. In silico putative lncRNA-miRNA association study unravels the endogenous miRNA sponge associated with our candidate lncRNAs. These findings were validated by small-interfering RNA (siRNA) knockdown assay of the candidate lncRNAs conducted in primary endothelial cells.

RESULTS

 We identified 1,524 DE mRNAs and 973 DE lncRNAs. Co-expressed protein-coding gene analysis resulted in a list of 722 co-expressed protein-coding genes with a Pearson correlation coefficients >0.7. The functional annotation of co-expressed genes and putative proteins revealed their involvement in the hypoxia, immune response, and coagulation cascade. Through its miRNA response elements to compete for miR-143 and miR-15, lncRNA-LINC00659 and UXT-AS1 regulate the expression of prothrombotic genes. Furthermore, in vitro RNA interference (siRNA) simultaneously suppressed lncRNAs and target gene mRNA level.

CONCLUSION

 This transcriptome profile describes novel potential mechanisms of interaction between lncRNAs, the coding genes, miRNAs, and regulatory transcription factors that define the thrombotic signature and may be used in establishing lncRNAs as a biomarker in HA-DVT.