Upregulation of nuclear‐enriched abundant transcript 1 confers oxaliplatin resistance to gastric cancer

LncRNA in gastric cancer drug resistance: deciphering the therapeutic strategies

Gastric cancer (GC) is an exceedingly aggressive disease and ranks as the third leading cause of cancer-related deaths, which poses a huge health burden globally. Chemotherapy is commonly employed during the middle to advanced stages of cancer, although it faces frequent treatment failures attributed to drug resistance. Thus, it is imperative for researchers to identify potential targets for overcoming therapeutic resistance, thereby facilitating the development of novel anti-cancer agents for GC patients with advanced stages. Long noncoding RNAs (lncRNAs) are a diverse group of transcripts with limited protein-coding capacity, which have been recognized for functional molecules for regulating cancer progression including cell proliferation, metastasis, and drug resistance in GC. In this review, we examine the intricate molecular networks on the role of lncRNAs in drug resistance of GC. LncRNAs conferred cancer cell resistance to anti-cancer drug through various molecular mechanisms, therefore functioning as promising therapeutic targets for GC patients. Additionally, we discuss current advancements of strategies targeting lncRNAs in cancer therapy, which may pave the way for lncRNA-mediated precision medicine for this malignant disease.

Identification of key lncRNAs associated with oxaliplatin resistance in colorectal cancer cells and isolated exosomes: From In-Silico prediction to In-Vitro validation

One of the critical challenges in managing colorectal cancer (CRC) is the development of oxaliplatin (OXP) resistance. Long non-coding RNAs (lncRNAs) have a crucial role in CRC progression and chemotherapy resistance, with exosomal lncRNAs emerging as potential biomarkers. This study aimed to predict key lncRNAs involved in OXP-resistance using in-silico methods and validate them using RT-qPCR methods in CRC cells and their isolated exosomes. Two public datasets, GSE42387 and GSE119481, were downloaded from the GEO database to identify differentially expressed genes (DEGs) and miRNAs (DEmiRNAs) associated with OXP-resistance in the HCT116 cell line. The analysis of GSE42387 revealed 210 DEGs, and GSE119481 identified 73 DEmiRNAs. A protein-protein interaction (PPI) network analysis of the DEGs identified 133 interconnected genes, from which the top ten genes with the highest degree scores were selected. By intersecting predicted miRNAs targeting these genes with the DEmiRNAs, 38 common miRNAs were found. Subsequently, 224 lncRNAs targeting these common miRNAs were predicted. LncRNA-miRNA-mRNA network were constructed and the top five lncRNAs with the highest degree scores were identified. Analysis using the Kaplan-Meier plotter database revealed that the key lncRNAs NEAT1, OIP5-AS1, and MALAT1 are significantly associated with the overall survival of CRC patients. To validate these lncRNAs, OXP-resistant HCT116 sub-cell line (HCT116/OXR) was developed by exposing parental HCT116 cells to gradually increasing concentrations of OXP. Exosomes derived from both HCT116 and HCT116/OXR cells were isolated and characterized utilizing dynamic light scattering (DLS), transmission electron microscopy (TEM), and Western blotting. RT-qPCR confirmed elevated levels of NEAT1, OIP5-AS1, and MALAT1 in HCT116/OXR cells and their exosomes compared to parental HCT116 cells and their exosomes. This study concludes that NEAT1, OIP5-AS1, and MALAT1 are associated with the OXP-resistance in CRC. The high levels of these lncRNAs in exosomes of resistant cells suggest their involvement in intercellular communication and resistance propagation. This positioning makes them promising biomarkers for OXP-resistance in CRC.

Loss of miR-26b-5p promotes gastric cancer progression via miR-26b-5p-PDE4B/CDK8-STAT3 feedback loop

BACKGROUND

Chronic inflammation is a well-known risk factor for the development of gastric cancer (GC). Nevertheless, the molecular mechanisms underlying inflammation-related GC progression are incompletely defined.

METHODS

Bioinformatic analysis was performed based on data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), and the expression of miR-26b-5p in GC cells and tissues was validated by quantitative real-time PCR (qRT-PCR). Cell proliferation was examined through Cell Counting Kit-8 (CCK8), 5-Ethynyl-2'-deoxyuridine (EdU), colony formation, flow cytometry, and tumor xenografts. Correlation between miR-26b-5p and Cyclin dependent kinase 8 (CDK8) or Phosphodiesterase 4B (PDE4B) was analyzed by dual-luciferase reporter assays, qRT-PCR, and Western blot. The effect of miR-26b-5p on the Signal transducer and activator of transcription 3 (STAT3) pathway was investigated using Western blot, immunofluorescence (IF), and immunohistochemistry (IHC). The impact of STAT3 on miR-26b-5p was determined by dual-luciferase reporter assays and qRT-PCR.

RESULTS

The expression of miR-26b-5p was significantly downregulated in Helicobacter Pylori (H. pylori)-infected GC cells. The decreased expression of miR-26b-5p was also detected in GC cells and tissues compared to normal gastric epithelium cells (GES1) and normal adjacent gastric tissues. The low expression of miR-26b-5p promoted GC proliferation in vitro and in vivo and was related to the poor outcome of GC patients. In terms of mechanism, miR-26b-5p directly targeted PDE4B and CDK8, resulting in decreased phosphorylation and nuclear translocation of STAT3, which was associated with the regulation of GC proliferation by miR-26b-5p. Notably, miR-26b-5p was transcriptionally suppressed by STAT3, thus forming the miR-26b-5p-PDE4B/CDK8-STAT3 positive feedback loop.

CONCLUSION

The newly identified miR-26b-5p-PDE4B/CDK8-STAT3 feedback loop plays an important role in inflammation-related GC progression and may serve as a promising therapeutic target for GC.

Long Non-Coding RNA in Gastric Cancer: Mechanisms and Clinical Implications for Drug Resistance

Gastric cancer (GC) is the third leading cause of cancer-related deaths worldwide, with high recurrence and mortality rate. Chemotherapy, including 5-fluorouracil (5-FU), adriamycin (ADR), vincristine (VCR), paclitaxel (PTX), and platinum drugs, remains one of the fundamental methods of GC treatment and has efficiently improved patients’ prognosis. However, most patients eventually develop resistance to chemotherapeutic agents, leading to the failure of clinical treatment and patients’ death. Recent studies suggest that long non-coding RNAs (lncRNAs) are involved in the drug resistance of GC by modulating the expression of drug resistance-related genes via sponging microRNAs (miRNAs). Moreover, lncRNAs also play crucial roles in GC drug resistance via a variety of mechanisms, such as the regulation of the oncogenic signaling pathways, inhibition of apoptosis, induction of autophagy, modulation of cancer stem cells (CSCs), and promotion of the epithelial-to-mesenchymal transition (EMT) process. Some of lncRNAs exhibit great potential as diagnostic and prognostic biomarkers, as well as therapeutic targets for GC patients. Therefore, understanding the role of lncRNAs and their mechanisms in GC drug resistance may provide us with novel insights for developing strategies for individual diagnosis and therapy. In this review, we summarize the recent findings on the mechanisms underlying GC drug resistance regulated by lncRNAs. We also discuss the potential clinical applications of lncRNAs as biomarkers and therapeutic targets in GC.

The relation between NEAT1 expression level and survival rate in patients with oral squamous cell carcinoma

Background/purpose

Numerous studies have shown that long noncoding RNAs (lncRNAs) are involved in cancer progression and chemotherapy resistance. Nuclear enriched abundant transcript 1 (NEAT1) is an lncRNA. It affects tumor cell progression and drug resistance in various tumors. However, the relation of NEAT1 and survival rate in oral squamous cell carcinoma (OSCC) requires further study.

Materials and methods

One normal gingival epithelium cell line, SG, three oral cancer cell lines (HSC3, OEC-M1, and SAS), 34 paired non-cancerous matched tissues (NCMT), and OSCC tissues were used in this study. Tri-reagent was used for total RNA extraction. NEAT1 expression was assessed by reverse transcription-quantitative PCR (RT-qPCR).

Results

NEAT1 expression in oral cancer cell lines was lower than that in normal cells and was significantly downregulated in OSCC. NEAT1 upregulation reduced the survival rate of patients with OSCC. NEAT1 upregulation also reduced the survival rate of OSCC patients treated with chemotherapy and radiotherapy.

Conclusion

These results indicate that NEAT1 expression is a valuable biomarker for the prediction and prognosis of oral cancer.

Mechanisms of Action And Clinical Implications of MicroRNAs in the Drug Resistance of Gastric Cancer

Gastric cancer (GC) is one of the most common malignant tumors of digestive systems worldwide, with high recurrence and mortality. Chemotherapy is still the standard treatment option for GC and can effectively improve the survival and life quality of GC patients. However, with the emergence of drug resistance, the clinical application of chemotherapeutic agents has been seriously restricted in GC patients. Although the mechanisms of drug resistance have been broadly investigated, they are still largely unknown. MicroRNAs (miRNAs) are a large group of small non-coding RNAs (ncRNAs) widely involved in the occurrence and progression of many cancer types, including GC. An increasing amount of evidence suggests that miRNAs may play crucial roles in the development of drug resistance by regulating some drug resistance-related proteins as well as gene expression. Some also exhibit great potential as novel biomarkers for predicting drug response to chemotherapy and therapeutic targets for GC patients. In this review, we systematically summarize recent advances in miRNAs and focus on their molecular mechanisms in the development of drug resistance in GC progression. We also highlight the potential of drug resistance-related miRNAs as biomarkers and therapeutic targets for GC patients.

The effects of miR-26b-5p on fibroblast-like synovial cells in rheumatoid arthritis (RA-FLS) via targeting EZH2

OBJECTIVE

To study the possible effects of miR-26b-5p on fibroblast-like synovial cells in rheumatoid arthritis (RA-FLS) through targeting enhancer of zeste homolog 2 (EZH2).

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect miR-26b-5p and EZH2 expressions in synovial tissues of RA patients and healthy controls. Dual luciferase reporter assay was adopted to verify the targeting relationship between miR-26b-5p and EZH2. RA-FLS was divided into Blank, mimics NC, mimics, NC siRNA, EZH2 siRNA and inhibitors + EZH2 siRNA groups, followed by the assessment of proliferation, apoptosis, migration and invasion. The expression of genes and proteins in RA-FLS was tested by qRT-PCR and western blotting, respectively.

RESULTS

MiR-26b-5p expression was lower, while EZH2 expression was higher in synovial tissue of RA patients than healthy controls; and miR-26b-5p was negatively correlated with the EZH2 in synovial tissue of RA patients, which were both related with disease activities. MiR-26b-5p can target EZH2 in RA-FLS. In vitro, miR-26b-5p mimics down-regulated EZH2 expression in RA-FLS. Compared with EZH2 siRNA group, the miR-26b-5p expression in inhibitors + EZH2 siRNA group was reduced, but EZH2 expression was increased. EZH2 siRNA inhibited the proliferation, invasion and migration of RA-FLS, promoted cell apoptosis, and inhibited the expression of TNF-α, IL-1β, IL-6, IL-17, MMP-2, MMP-9, which were reversed by miR-26b-5p inhibitor.

CONCLUSION

MiR-26b-5p may affect the biological characteristics of RA-FLS via targeting EZH2, including proliferation, apoptosis, invasion and migration, as well as the secretion of cytokines, thus playing a potential therapeutic role in RA.