Long non-coding RNA SNHG17 promotes gastric cancer progression by inhibiting P15 and P16

Functional role of lncRNAs in gastrointestinal malignancies: the peculiar case of small nucleolar RNA host gene family

Long noncoding RNAs (lncRNAs) play crucial roles in normal physiology and are often de-regulated in disease states such as cancer. Recently, a class of lncRNAs referred to as the small nucleolar RNA host gene (SNHG) family have emerged as important players in tumourigenesis. Here, we discuss new findings describing the role of SNHGs in gastrointestinal tumours and summarize the three main functions by which these lncRNAs promote carcinogenesis, namely: competing with endogenous RNAs, modulating protein function, and regulating epigenetic marking. Furthermore, we discuss how SNHGs participate in different hallmarks of cancer, and how this class of lncRNAs may serve as potential biomarkers in cancer diagnosis and therapy.

Low SP1 SUMOylation-dependent SNHG17 upregulation promotes drug resistance of gastric cancer through impairing hsa-miR-23b-3p-induced Notch2 inhibition

OBJECTIVE

Specificity protein 1 (SP1), a transcription factor mediated by SUMOylation modifiers, is upregulated in gastric cancer (GC) and shares negative correlation with patient prognosis. Here, we paid main attention to the role of SP1 SUMOylation in the drug resistance of GC cells and the possible long non-coding RNA (lncRNA) SNHG17/microRNA-23b-3p (miR-23b-3p)/Notch2 network engaged in this process.

METHODS

Tumor tissues and non-tumor tissues were isolated from GC patients who received treatment with capecitabine and cisplatin (DDP). Co-immunoprecipitation was utilized to detect the SUMOylation level of SP1. Using gain- and loss-of-function approaches, we assessed the impacts of SNHG17/miR-23b-3p/Notch2 on sensitivity of DDP-resistant GC cells in vitro and in vivo. A series of assays such as luciferase activity detection and RNA pull-down were conducted for mechanistic exploration.

RESULTS

SP1 expression was increased due to low SP1 SUMOylation level in the recurrent GC tissues. This increase led to upregulated SNHG17 expression and SP1 binding sites existed in the SNHG17 promoter. In addition, SNHG17 could bind to miR-23b-3p while miR-23b-3p targeted Notch2. Loss of SNHG17 reduced the resistance of DDP-resistant GC cells to DDP, which was achieved through miR-23b-3p-dependent Notch2 inhibition. Finally, SP1 silencing attenuated the resistance of GC to DDP in mice.

CONCLUSION

Low SP1 SUMOylation induces SNHG17 upregulation and blocks miR-23b-3p-induced Notch2 inhibition, contributing to the resistance of GC to DDP. This study may aid in the development of therapeutic targets overcoming the chemoresistance of GC.

Integrative pan-cancer analysis indicates the prognostic importance of long noncoding RNA SNHG17 in human cancers

BACKGROUND

Cancer is one of the most widespread causes of death today. Early diagnosis can dramatically reduce cancer-related mortality. Studies have shown that the lncRNA Small Nucleolar RNA Host Gene 17 (SNHG17) is aberrantly expressed in various types of solid tumors. Nevertheless, its prognostic value remains to be elucidated. The main objective of this meta-analysis was to elucidate whether SNHG17 can be considered as a potential prognostic biomarker for a variety of cancers.

METHODS

Correlational studies were screened from Cochrane, Embase, PubMed, and Web of Science. Hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were pooled, and the role of SNHG17 in cancer was analyzed. The Cancer Genome Atlas (TCGA) database was employed to verify the results.

RESULTS

Seventeen original papers including 1451 patients were included in the meta-analysis. SNHG17 expression was upregulated in various cancers. Overexpression of SNHG17 was significantly correlated with worse overall survival (OS) (HR = 1.92, 95% CI 1.55-2.37, P < 0.001) and relapse-free survival (RFS) (HR = 1.87, 95% CI 1.06-3.30, P = 0.030). Furthermore, overexpression of SNHG17 was predictive of earlier lymph node metastasis (LNM) (OR = 2.94, 95% CI 2.29-3.78, P < 0.001), more advanced tumor-node-metastases (TNM) stage (OR = 3.56, 95% CI 2.22-5.68, P < 0.001), larger tumor size (OR = 2.18, 95% CI 1.65-2.88, P < 0.001), worse differentiation grade (OR = 1.69, 95% CI 1.26-2.25, P < 0.001), and earlier distant metastasis (DM) (OR = 1.63, 95% CI 1.03-2.56, P = 0.033) in human cancers. Moreover, further inquiry based on TCGA dataset validated that SNHG17 was high expression in various tumors and foresaw unfavorable clinical prognosis.

CONCLUSIONS

Overexpression of SNHG17 correlates with poor prognosis and advanced clinicopathological features in cancer patients and may be a potential prognostic indicator and a therapeutic target for cancer treatment.

Enabling factor for cancer hallmark acquisition: Small nucleolar RNA host gene 17

The role of long non-coding RNA (lncRNA) in human tumors has gradually received increasing attention in recent years. Particularly, the different functions of lncRNAs in different subcellular localizations have been widely investigated. The upregulation of lncRNA small nucleolar RNA host gene 17 (SNHG17) has been observed in various human tumors. Growing evidence has proved that SNHG17 plays a tumor-promoting role in tumorigenesis and development. This paper describes the molecular mechanisms by which SNHG17 contributes to tumor formation and development. The different functions of SNHG17 in various subcellular localizations are also emphasized: its function in the cytoplasm as a competing endogenous RNA (ceRNA), its action in the nucleus as a transcriptional coactivator, and its function through the polycomb repressive complex 2 (PRC2)-dependent epigenetic modifications that regulate transcriptional processes. Finally, the correlation between SNHG17 and human tumors is summarized. Its potential as a novel prognostic and diagnostic biomarker for cancer is explored especially.

LncRNA POT1-AS1 accelerates the progression of gastric cancer by serving as a competing endogenous RNA of microRNA-497-5p to increase PDK3 expression

BACKGROUND

Gastric cancer (GC) is the most common malignant tumor of the digestive system. Although progress has been reported in terms of treatment, it is still the second leading cause of cancer-related death. Long non-coding RNAs have been shown to play a key role in human cancers in recent investigations. However, the role of POT1-AS1 in GC is still unclear.

METHODS

The relative POT1-AS1 level in GC tissues and paracancerous tissues was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The biological function of POT1-AS1 was studied by CCK8 and Transwell assays in vitro experiments. Moreover, the downstream target genes of POT1-AS1 were predicted by bioinformatics.

RESULTS

In this study, high POT1-AS1 expression in GC cells was confirmed, and its elevated expression was linked to patients' negative clinicopathological characteristics, as well as shorter disease-free survival (DFS) and overall survival (OS). POT1-AS1 was shown to serve as a competing endogenous RNA (ceRNA) by sponging miR-497-5p to increase PDK3 expression. The impact of POT1-AS1 silencing on GC malignant phenotypes could be reversed by suppressing miR-497-5p or restoring PDK3, according to rescue experiments.

CONCLUSIONS

In brief, POT1-AS1 acted as an oncogenic lncRNA in GC, facilitating GC development by affecting the miR-497-5p/PDK3 axis, implying that the POT1-AS1/miR-497-5p/PDK3 axis is a useful target in anticancer therapy.