LINC00240 promotes gastric cancer cell proliferation, migration and EMT via the miR-124-3p / DNMT3B axis.

Gastric cancer (GC) remains one of prevalent causes of cancer-related deaths worldwide. Long noncoding RNA is related to various cancers. Our study was conducted to explore the biological effects of LINC00240 on the tumorigenesis of GC and uncover its possible mechanisms. LINC00240 expression was determined in GC cell lines and samples through quantitative Real-time Polymerase Chain Reaction (qRT-PCR). The functional effects of LINC00240 were validated using in vitro and in vivo assays. Targets were assessed by AGO2-dependent RNA immunoprecipitation assay and dual-luciferase report assays. Our findings suggested higher LINC00240 expression in GC tissues and cells. Through downregulating LINC00240, cell proliferation, invasion and migration were retarded in vitro, and tumorigenesis of GC cells was notably suppressed in vivo. Further research showed that LINC00240 was a cytoplasmic lncRNA that shared miRNA response elements of microRNA (miR)-124-3p with DNMT3B, thus forming a LINC00240/miR-124-3p/DNMT3B axis explaining the functions of LINC00240. In a word, our study reveals that LINC00240 promotes GC tumorigenesis via a LINC00240/miR-124-3p/DNMT3B axis as an oncogene. These findings objectivise that LINC00240 may be a potential diagnostic biomarker for GC. SIGNIFICANCE OF THE STUDY: Gastric cancer (GC) is the fifth most common cancer and the third leading cause of cancer-related death across the world. Then we analysed lncRNA microarray of GC and selected LINC00240 as the study object. Therefore, the potential molecular mechanism as well as physiological function of LINC00240 in GC was discussed. Then we reveal that LINC00240 acts as an oncogene in GC progression via the miR-99a-5p/IGF1R axis. This study is the first to demonstrate the roles of LINC00240 in GC.

Li Y ，Yan J ，Wang Y ，Wang C ，Zhang C ，Li G ... -  《-》

lncRNA SNHG4 enhanced gastric cancer progression by modulating miR-409-3p/CREB1 axis.

Gastric cancer (GC) is a globally common cancer characterized by high incidence and mortality worldwide. Advances in the molecular understanding of GC provide promising targets for GC diagnosis and therapy. Long non-coding RNAs (lncRNAs) and their downstream regulators are regarded to be implicated in the progression of multiple types of malignancies. Studies have shown that the lncRNA small nucleolar RNA host gene 4 (SNHG4) serves as a tumor promoter in various malignancies, while its function in GC has yet to be characterized. Therefore, our study aimed to explore the role and underlying mechanism of SNHG4 in GC. We used qRT-PCR to analyze SNHG4 expression in GC tissues and cells. Kaplan-Meier analysis was used to assess the correlation between SNHG4 expression and the survival rate of GC patients. Cellular function experiments such as CCK-8, BrdU, colony formation, flow cytometry analysis, and transwell were performed to explore the effects of SNHG4 on GC cell proliferation, apoptosis, cell cycle, migration, and invasion. We also established xenograft mouse models to explore the effect of SNHG4 on GC tumor growth. Mechanically, dual luciferase reporter assay was used to verify the interaction between SNHG4 and miR-409-3p and between miR-409-3p and cAMP responsive element binding protein 1 (CREB1). The results indicated that SNHG4 was overexpressed in GC tissues and cell lines, and was linked with poor survival rate of GC patients. SNHG4 promoted GC cell proliferation, migration, and invasion while inhibiting cell apoptosis and cell cycle arrest in vitro. The in vivo experiment indicated that SNHG4 facilitated GC tumor growth. Furthermore, SNHG4 was demonstrated to bind to miR-409-3p. Moreover, CREB1 was directly targeted by miR-409-3p. Rescue assays demonstrated that miR-409-3p deficiency reversed the suppressive impact of SNHG4 knockdown on GC cell malignancy. Additionally, miR-409-3p was also revealed to inhibit GC cell proliferation, migration, and invasion by targeting CREB1. In conclusion, we verified that the SNHG4 promoted GC growth and metastasis by binding to miR-409-3p to upregulate CREB1, which may deepen the understanding of the underlying mechanism in GC development.

Cheng Z ，Hua Y ，Cao Y ，Qin J ... -  《-》

miR-29c plays a suppressive role in breast cancer by targeting the TIMP3/STAT1/FOXO1 pathway.

Li W ，Yi J ，Zheng X ，Liu S ，Fu W ，Ren L ，Li L ，Hoon DSB ，Wang J ，Du G ... -  《-》

EGCG targeting STAT3 transcriptionally represses PLXNC1 to inhibit M2 polarization mediated by gastric cancer cell-derived exosomal miR-92b-5p.

M2-polarized tumor-associated macrophages (TAMs) predominate in tumor microenvironment (TME) and serve primary functions in tumor progression, including growth, angiogenesis, metastasis, immunosuppression, chemoresistance, and poor prognosis. The reversal of M2 polarization provides a new treatment strategy for cancer. Presently, the molecular mechanisms of M2 polarization have yet to be fully characterized, and there is a lack of effective therapeutic targets and drugs. Cancer cells initiate an immunosuppressive TME by recruiting macrophages and promoting M2 polarization through the secretion of inflammatory factors. Accordingly, blocking cancer cell-induced TAM M2 polarization may present a more effective strategy from the perspective of cancer cells. Hedyotis diffusa Willd (HDW) possesses immunomodulatory and antitumor properties, and is a precious and direct source of small molecule natural products with a dual function of inhibition of tumor growth and tumor cell-mediated M2 polarization. To identify a new target promoting gastric cancer (GC) cell growth and GC cell-mediated M2 polarization from mRNA profiles of GC cells treated with HDW injection (HDI) and to excavate a natural product from HDI that can regulate related mRNA and inhibit the aforementioned effects. RNA sequencing (RNA-seq) was used to analyze HDI-regulated differentially expressed mRNAs (HRmRNAs) in MKN45 cells. Weighted gene co-expression network analysis (WGCNA), univariate and multivariate Cox regression analysis, KM survival curves, and association analysis between HRmRNA and clinical characteristics/tumor infiltrating immune cells (TIICs) individually were utilized to screen out the target HRmRNA associated with prognosis and M2 macrophage infiltration in GC. shRNA lentiviral vectors were used for stably silencing, and transient overexpressing plasmids were constructed for overexpression. CCK8, EdU, colony formation, migration and invasion assays were used to validate the function of drugs and molecules in GC. HDI constituent analysis was performed using UHPLC-QE-MS. A network of HDI constituent-hub transcription factor (TF)-HRmRNA was constructed based on RNA-Seq, network pharmacology and TFs prediction. Exosome isolation and identification were performed using ultracentrifugation, NTA, TEM and western blot. Apoptosis and macrophage phenotypes were determined by flow cytometric analysis. Small RNA-Seq made exosomal miRNA identification. Small molecule interaction with targets were analyzed using molecular docking, SPR and CETSA. The direct relationship between transcription factors and promoters was verified using ChIP-QPCR and dual-luciferase reporter gene assay. A nude mice xenograft tumor model was established for vivo validation. HDI inhibited MKN45 cell proliferation, migration, invasion and promoted apoptosis. RNA-Seq identified 2583 HRmRNAs. PLXNC1 was screened out as the target HRmRNA associated with prognosis and M2 macrophage infiltration in GC. PLXNC1 promoted GC cell proliferation and facilitated TAMs M2 polarization by transferring GC cell-derived exosomal miR-92b-5p, inhibiting SOCS7-STAT3 interactions and subsequently activating STAT3 in macrophages. M2 TAMs induced by PLXNC1-mediated GC cell-derived exosomes promoted GC cell migration and invasion. PLXNC1 regulated exosomal miR-92b-5p through the MEK1/MSK1/CREB1 pathway. STAT3 could transcriptionally regulate PLXNC1 expression in GC cells. The network of HDI constituent-hub TF-HRmRNA showed epigallocatechin gallate (EGCG) from HDI targeted STAT3 to transcriptionally regulate PLXNC1 expression. EGCG as a natural product directly bound to STAT3 to diminish its nuclear localization, resulting in the transcriptional repression of PLXNC1 and the reversal of M2 polarization induced by PLXNC1-mediated GC cell-derived exosomes. PLXNC1 is a novel target exerting dual effects on GC cell proliferation and GC cell-mediated M2 polarization. EGCG derived from HDI inhibits GC cell proliferation and targets STAT3 to inhibit M2 polarization induced by PLXNC1-mediated exosomes derived from GC cells, which may be a multi-target therapeutic agent for GC cell proliferation and immune microenvironment.

Yi J ，Ye Z ，Xu H ，Zhang H ，Cao H ，Li X ，Wang T ，Dong C ，Du Y ，Dong S ，Zhou W ... -  《-》

LINC00922 promotes the proliferation, migration, invasion and EMT process of liver cancer cells by regulating miR-424-5p/ARK5.

AMPK-related protein kinase 5 (ARK5) promotes the deterioration of hepatocellular carcinoma (HCC). From the perspective of lncRNA-miRNA-mRNA, this study explored in-depth the intervention mechanism of ARK5. The binding relationship between miR-424-5p and two genes (LINC00922 and ARK5) were analyzed by Bioinformatics and dual-luciferase experiments. After clinical sample collection, the expressions of miR-424-5p, LINC00922 and ARK5 in HCC tissues were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The correlation between LINC00922, miR-424-5p, and ARK5 in HCC tissues was analyzed by Pearson correlation. The influences of miR-424-5p, LINC00922 and ARK5 on the basic functions (viability, migration and invasion) of cancer cells were detected by cell counting kit-8, wound healing, and Transwell experiments, and their regulatory effects on related genes, as well as their relationship, were tested by qRT-PCR and Western blot. MiR-424-5p was low expressed, whereas LINC00922 and ARK5 were high expressed in HCC tissues. MiR-424-5p was negatively associated with LINC00922 and ARK5 that was positively associated with LINC00922. Interestingly, LINC00922 partially shared an identical binding site of miR-424-5p with ARK5. LINC00922 its overexpression partially offset the inhibitory effect of miR-424-5p on cancer cell functions. ARK5 silencing repressed the malignant phenotype of cancer cells and inhibited the expressions of epithelial-to-mesenchymal transition (EMT)-related molecules (Vimentin, Snail and N-Cadherin). However, these effects were partially neutralized by miR-424-5p inhibitors. LINC00922 increases the cell viability, migration, invasion and EMT process of HCC cells by regulating the miR-424-5p/ARK5 axis, and thus may serve as a potential target for targeted therapy.

Ye Z ，He Q ，Wang Q ，Lin Y ，Cen K ，Chen X ... -  《-》