Oncogenic role of long non-coding RNA SNHG12 in gastric cancer cells by targeting miR-16

Gastric cancer cell-derived extracellular vesicles elevate E2F7 expression and activate the MAPK/ERK signaling to promote peritoneal metastasis through the delivery of SNHG12

Cancer cell-derived extracellular vesicles (EVs) have extensive application in the formation of their environment, including metastasis. This study explored the ability of gastric cancer (GC) cell-derived EVs-mediated microRNA-129-5p/E2F transcription factor 7/mitogen-activated protein kinase/extracellular regulated protein kinase (miR-129-5p/E2F7/MAPK/ERK) axis to affect the peritoneal metastasis of GC by delivering lncRNA small nucleolar RNA host gene 12 (SNHG12). EV-derived lncRNA and SNHG12/miR-129-5p/E2F7 network were determined by bioinformatics analysis. The regulatory relationship among SNHG12, miR-129-5p, and E2F7 was verified using a combination of dual-luciferase reporter gene, RNA immunoprecipitation, and RNA pull-down assays. The SNHG12, miR-129-5p, and E2F7 expression was measured by RT-qPCR. After GC cell-derived EVs were isolated and co-cultured with human peritoneal mesothelial cells (HPMCs), the uptake of EVs by HPMCs was observed under laser scanning confocal microscopy. Cell viability and apoptosis were examined using cell counting kit-8 and flow cytometry, respectively. Western blot analysis was performed to measure the mesothelial–mesenchymal transition (MMT)-related protein expression. The pathological and morphological characteristics of metastatic tumors in nude mice were observed by hematoxylin–eosin staining. A high SNHG12 expression was correlated with the poor prognosis of patients with GC. GC-derived EVs led to increased HPMC apoptosis and MMT by transferring SNHG12, whereas the knockdown of SNHG12 annulled the aforementioned results. SNHG12 sponged miR-129-5p to boost E2F7 expression and activate the MAPK/ERK signaling, thus inducing HPMC apoptosis and MMT. In vivo experiments further verified that EVs derived from GC cells promoted peritoneal metastasis in nude mice. GC cell-derived EVs elevated the E2F7 expression and activated the MAPK/ERK signaling to promote peritoneal metastasis through the delivery of SNHG12.

The Long Non-Coding RNA SNHG12 as a Mediator of Carboplatin Resistance in Ovarian Cancer via Epigenetic Mechanisms

Simple Summary

Epithelial ovarian cancer is a lethal malignancy in which recurrence and therapy resistance are the major causes of death. We investigated the transcriptome and DNA methylation profile of ovarian cancer cell lines sensitive and resistant to carboplatin, aiming to identify genes associated with therapy resistance. We focused on long non-coding RNAs (lncRNAs), known as epigenetic regulators of several cellular and biological processes. We found 11 lncRNAs associated with carboplatin resistance, including SNHG12 (small nucleolar RNA host gene 12), also confirmed in an external dataset (The Cancer Genome Atlas). SNHG12 gene silencing increased the sensitivity to carboplatin, giving evidence that this lncRNA contributes to resistance to carboplatin in ovarian cancer cell lines. We also demonstrated that SNHG12 could control the expression of nearby genes probably by altering epigenetic markers and modifying the transcript levels.

Abstract

Genetic and epigenetic changes contribute to intratumor heterogeneity and chemotherapy resistance in several tumor types. LncRNAs have been implicated, directly or indirectly, in the epigenetic regulation of gene expression. We investigated lncRNAs that potentially mediate carboplatin-resistance of cell subpopulations, influencing the progression of ovarian cancer (OC). Four carboplatin-sensitive OC cell lines (IGROV1, OVCAR3, OVCAR4, and OVCAR5), their derivative resistant cells, and two inherently carboplatin-resistant cell lines (OVCAR8 and Ovc316) were subjected to RNA sequencing and global DNA methylation analysis. Integrative and cross-validation analyses were performed using external (The Cancer Genome Atlas, TCGA dataset, n = 111 OC samples) and internal datasets (n = 39 OC samples) to identify lncRNA candidates. A total of 4255 differentially expressed genes (DEGs) and 14529 differentially methylated CpG positions (DMPs) were identified comparing sensitive and resistant OC cell lines. The comparison of DEGs between OC cell lines and TCGA-OC dataset revealed 570 genes, including 50 lncRNAs, associated with carboplatin resistance. Eleven lncRNAs showed DMPs, including the SNHG12. Knockdown of SNHG12 in Ovc316 and OVCAR8 cells increased their sensitivity to carboplatin. The results suggest that the lncRNA SNHG12 contributes to carboplatin resistance in OC and is a potential therapeutic target. We demonstrated that SNHG12 is functionally related to epigenetic mechanisms.

miR-140-3p is involved in the occurrence and metastasis of gastric cancer by regulating the stability of FAM83B

Background

Gastric cancer (GC) is a malignant tumor and microRNAs (miRNAs) are closely connected to GC development. The purpose of this study is to investigate the effect of miR-140-3p on the occurrence and metastasis of GC.

Methods

We detected miR-140-3p expression in GC cells and tissues. The correlation between miR-140-3p and prognosis and clinicopathological features in GC was analyzed. The role of miR-140-3p in GC cell migration, invasion, and proliferation was analyzed. The model of tumor transplantation and metastasis in nude mice was established, and the effect of miR-140-3p on the development and metastasis of GC was assessed. The relation between miR-140-3p and SNHG12 and the relations among HuR, SNHG12, and FAM83B were analyzed.

Results

miR-140-3p was poorly expressed in GC. GC patients with low miR-140-3p expression had a poor prognosis and unfavorable clinicopathologic features. Overexpression of miR-140-3p inhibited GC cell migration, invasion, and proliferation, and inhibited the development and metastasis of GC. miR-140-3p directly bound to SNHG12 in GC tissues and downregulated SNHG12 expression. SNHG12 overexpression induced HuR nuclear transportation. HuR can bind to FAM83B and up-regulate the mRNA level of FAM83B. Overexpression of SNHG12 or FAM83B reduced the inhibition of overexpression of miR-140-3p on GC.

Conclusion

miR-140-3p directly bound to SNHG12 in GC and down-regulated the expression of SNHG12, reduced the binding of SNHG12 and HuR, thus inhibiting the nuclear transportation of HuR and the binding of HuR and FAM83B, and reducing the transcription of FAM83B, and finally inhibiting the growth and metastasis of GC.

Long Noncoding RNA SNHG12 Promotes Gastric Cancer Proliferation by Binding to HuR and Stabilizing YWHAZ Expression Through the AKT/GSK-3β Pathway

Background

Gastric cancer (GC) is a malignancy with high morbidity and mortality rates worldwide. SNHG12 is a long noncoding RNA (lncRNA) commonly involved many types of cancers in the contexts of tumorigenesis, migration and drug resistance. Nevertheless, its role in GC proliferation is poorly understood.

Methods

Bioinformatics and qRT-PCR assays were used to analyze the expression of SNHG12 in GC tissues and cells. In vitro and in vivo experiments were conducted to detect the role of SNHG12 in GC development. qRT-PCR, PCR, western blotting (WB), RNA binding protein immunoprecipitation (RIP), immunoprecipitation (IP), immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and in situ hybridization (ISH) were performed to investigate the underlying mechanisms by which SNHG12 promotes GC proliferation.

Results

SNHG12 was highly expressed in GC cells and tissues, and predicted poor survival. In vitro and in vivo assays showed that SNHG12 knockdown inhibited GC proliferation, while SNHG12 overexpression promoted GC proliferation. Further experiments confirmed that SNHG12 was mainly located in the cytoplasm and bound to HuR. Bioinformatics analysis predicted that YWHAZ was the common target of SNHG12 and HuR, and that the “SNHG12-HuR” complex enhanced the stability of YWHAZ mRNA. Furthermore, YWHAZ, which was highly expressed in GC, predicted poor survival and promoted GC proliferation by phosphorylating AKT. Rescue assays verified that SNHG12 promoted GC proliferation by activating the AKT/GSK-3β pathway.

Conclusions

SNHG12 binds to HuR and stabilizes YWHAZ. SNHG12 promotes GC proliferation via modulation of the YWHAZ/AKT/GSK-3β axis in vitro and in vivo. Thus, SNHG12 could become a novel therapeutic target for anti-tumor therapy.

YY1-modulated long non-coding RNA SNHG12 promotes gastric cancer metastasis by activating the miR-218-5p/YWHAZ axis

Long non-coding RNA (lncRNA) small nucleolar RNA host gene 12 (SNHG12) plays important roles in the pathogenesis and progression of cancers. However, the role of SNHG12 in the metastasis of gastric cancer (GC) has not yet been thoroughly investigated. In the present study, we demonstrated that SNHG12 was upregulated in GC tissues and cell lines. In addition, the expression level of SNHG12 in GC samples was significantly related to tumor invasion depth, TNM stage and lymph node metastasis and was associated with disease-free survival (DFS) and overall survival (OS) in GC patients. In vivo and in vitro assays indicated that SNHG12 promotes GC metastasis and epithelial-mesenchymal transition (EMT). Bioinformatics and mechanistic analyses revealed that SNHG12 can directly target miR-218-5p to regulate YWHAZ mRNA, forming an SNHG12/miR-218-5p/YWHAZ axis and decreasing the ubiquitination of β-catenin. In addition, SNHG12 stabilizes CTNNB1 mRNA by binding with HuR, thus activating the β-catenin signaling pathway. Further analysis also revealed that the transcription factor YY1 negatively modulates SNHG12 transcription. In conclusion, SNHG12 is a potential prognostic marker and therapeutic target for GC. Negatively modulated by YY1, SNHG12 promotes GC metastasis and EMT by regulating the miR-218-5p/YWHAZ axis and stabilizing CTNNB1 via activation of the β-catenin signaling pathway.

Long noncoding RNA SNHG12 promotes the proliferation, migration, and invasion of trophoblast cells by regulating the epithelial-mesenchymal transition and cell cycle

Objective

The deficient placental blood perfusion caused by the attenuated infiltration of trophoblast cells is a key factor in the occurrence of preeclampsia (PE). Furthermore, the long noncoding (lnc)RNA SNHG12 (small nucleolar RNA host gene 12) can promote the proliferation and metastasis of multiple tumor cells. However, whether lncRNA SNHG12 affects proliferation and metastasis of trophoblast cells is unclear.

Methods

We examined the level of lncRNA SNHG12 in plasma and placenta of patients with PE and constructed trophoblast cells with overexpressed or knocked down SNHG12. CCK-8, wound healing, and Transwell assays were used to detect alterations in proliferation, migration, and invasion of trophoblast cells. Western blotting was used to detect proteins related to the epithelial–mesenchymal transition (EMT), and cell cycle assays clarified cell cycle distribution.

Results

LncRNA SNHG12 promoted the proliferation, migration, and invasion of trophoblast cells. The expression of matrix metalloproteinase-2 (MMP-2) and MMP-9, β-catenin, and vimentin were positively correlated with SNHG12, and expression of E-cadherin was negatively correlated with SNHG12. SNHG12 also promoted the transition of trophoblast cells from G₀/G₁ to S phase.

Conclusion

Overall, lncRNA SNHG12 promoted the migration and invasion of trophoblast cells by inducing the progression of EMT.

The role of long non-coding RNAs in mediating chemoresistance by modulating autophagy in cancer

Cancer is a complex process in which protein-coding and non-coding genes play essential roles. Long noncoding RNAs (lncRNAs), as a subclass of noncoding genes, are implicated in various cancer processes including growth, proliferation, metastasis, and angiogenesis. Due to presence in body fluids such as blood and urine, lncRNAs have become novel biomarkers in cancer detection, diagnosis, progression, and therapy response. Remarkably, increasing evidence has verified that lncRNAs play essential roles in chemoresistance by targeting different signalling pathways. Autophagy, a highly conserved process in response to environmental stresses such as starvation and hypoxia, plays a paradoxical role in inducing resistance or sensitivity to chemotherapy agents. In this regard, we reviewed chemoresistance, the role of lncRNAs in cancer, and the role of lncRNAs in chemoresistance by modulating autophagy.

Prognostic Value of Long Noncoding RNA SNHG12 in Various Carcinomas: A Meta-Analysis

Background

Numerous recent studies suggested that overexpression of the long noncoding RNA small nucleolar RNA host gene 12 (SNHG12) exhibited prooncogenic activity in multiple cancers. However, results regarding the prognostic value of SNHG12 in cancers still remained controversial. Therefore, we conducted a meta-analysis complemented with bioinformatics analysis to elucidate the clinical significance of SNHG12 in cancer patients.

Methods

PubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang, and Weipu databases were searched for eligible studies until July 2020. Additionally, bioinformatics analysis was applied to verify the results of meta-analysis.

Results

Twenty-three related studies consisting of 1389 cancer patients were enrolled in the current meta-analysis. Elevated SNHG12 expression was found to be significantly associated with poor overall survival (OS) (HR = 1.81; 95% CI: 1.53-2.13; P < 0.001) and disease-free survival (DFS) (HR = 1.40; 95% CI: 1.12-1.76; P = 0.004) in multiple cancers, which were also verified by the results of bioinformatics analysis. Moreover, overexpression of SNHG12 was also related to clinicopathological characteristics including LNM, distant metastasis, high clinical stage, large tumor size, and poor tumor differentiation in diverse types of cancers.

Conclusion

The present findings indicated that SNHG12 might act as a novel biomarker for diagnosis or prognosis in human cancers.

Prognostic and clinical significance of long non-coding RNA SNHG12 expression in various cancers

Recently, increasing studies suggested that lncRNA SNHG12 was aberrantly expressed in kinds of cancers. However, definite prognostic value of SNHG12 remains unclear. We conducted this meta-analysis to evaluate the association between SNHG12 expression level and cancer prognosis. A literature retrieval was conducted by searching kinds of databases. The meta-analysis was performed by using Revman 5.2 and Stata 12.0 software. Besides, The Cancer Genome Atlas dataset was analyzed to validate the results in our meta-analysis via using Gene Expression Profiling Interactive Analysis. The pooled results showed that high SNHG12 expression significantly indicated worse overall survival and recurrence-free survival. Tumor type, sample size, survival analysis method, and cutoff value did not alter SNHG12 prognosis value according to stratified analysis results. Additionally, higher expression of SNHG12 suggested unfavorable clinicopathological outcomes including larger tumor size, lymph node metastasis, distant metastasis, and advanced clinical stage. Online cross-validation in TCGA dataset further indicated that cancer patients with upregulated SNHG12 expression had worse overall survival and disease-free survival. Therefore, elevated SNHG12 expression was associated with poor survival and unfavorable clinical outcomes in various cancers, and therefore might be a potential prognostic biomarker in human cancers.

Abbreviations Akt: protein kinase B; CESC: cervical squamous cell carcinoma and endocervical adenocarcinoma; ceRNA: competitive endogenous RNA; CNKI: China National Knowledge Infrastructure; CI: confidence interval; CCNE1: cyclin E1; COAD: colon adenocarcinoma; DM: distant metastasis; DFS: disease-free survival; EMT: epithelial–mesenchymal transition; FISH: fluorescence in situ hybridization; FIGO: the International Federation of Gynecology and Obstetrics; GEPIA: Gene Expression Profiling Interactive Analysis; HR: hazard ratio; HIFα: hypoxia-inducible factor 1 α; KIRC: kidney renal clear cell carcinoma; KIRP: kidney renal papillary cell carcinoma; LIHC: hepatocellular carcinoma; LNM: lymph node metastasis; mTOR: mechanistic target of rapamycin kinase; MMP-9: matrix metalloproteinase 9; MCL1: myeloid cell leukemia 1; MLK3: mixed-lineage protein kinase 3; N/A: not available; NOS: Newcastle-Ottawa Scale; OR: odd ratio; OS: overall survival; PSA: prostate-specific antigen; PI3K: phosphoinositide 3-kinase; qRT-PCR: quantitative real-time polymerase chain reaction; READ: rectum adenocarcinoma; RFS: recurrence-free survival; SARC: sarcoma; SNHG12: small nucleolar RNA host gene 12; STAT3: signal transducer and activator of transcription 3; SOX4: SRY-box transcription factor 4; SOX5: SRY-box transcription factor 5; STAD: stomach adenocarcinoma; TCGA: The Cancer Genome Atlas; TNM: tumor node metastasis; WWP1: WW domain-containing E3 ubiquitin protein ligase 1; WHO grade: World Health Organization grade; ZEB2: zinc finger E-box-binding homeobox 2