Long non-coding RNA SNHG7 promotes malignant melanoma progression through negative modulation of miR-9

Prognostic effect of lncRNA SNHG7 on cancer outcome: a meta and bioinformatic analysis

BACKGROUND

New evidence from clinical and fundamental researches suggests that SNHG7 is involved in the occurrence and development of carcinomas. And the increased levels of SNHG7 are associated with poor prognosis in various kinds of tumors. However, the small sample size was the limitation for the prognostic value of SNHG7 in clinical application. The aim of the present meta-analysis was to conduct a qualitative analysis to explore the prognostic value of SNHG7 in various cancers.

METHODS

Articles related to the SNHG7 as a prognostic biomarker for cancer patients, were comprehensive searched in several electronic databases. The enrolled articles were qualified via the preferred reporting items for systematic reviews and meta-analysis of observational studies in epidemiology checklists. Additionally, an online database based on The Cancer Genome Atlas (TCGA) was further used to validate our results.

RESULTS

We analyzed 2418 cancer patients that met the specified criteria. The present research indicated that an elevated SNHG7 expression level was significantly associated with unfavorable overall survival (OS) (HR = 2.45, 95% CI: 2.12-2.85, p <0.001). Subgroup analysis showed that high expression levels of SNHG7 were also significantly associated with unfavorable OS in digestive system cancer (HR = 2.31, 95% CI: 1.90-2.80, p <0.001) and non-digestive system cancer (HR = 2.67, 95% CI: 2.12-3.37, p <0.001). Additionally, increased SNHG7 expression was found to be associated with tumor stage and progression (III/IV vs. I/II: HR = 1.76, 95% CI: 1.57-1.98, p <0.001). Furthermore, elevated SNHG7 expression significantly predicted lymph node metastasis (LNM) (HR = 1.98, 95% CI: 1.74-2.26, p <0.001) and distant metastasis (DM) (HR = 2.49, 95% CI: 1.88-3.30, p <0.001) respectively. No significant heterogeneity was observed among these studies. SNHG7 was significantly upregulated in four cancers and the elevated expression of SNHG7 predicted shorter OS in four cancers, worse DFS in five malignancies and worse PFI in five carcinomas based on the validation using the GEPIA on-line analysis tool.

CONCLUSIONS

The present analysis suggests that elevated SNHG7 is significantly associated with unfavorable OS, tumor progression, LNM and DM in various carcinomas, and may be served as a promising biomarker to guide therapy for cancer patients.

Long Non-Coding RNA SNHG7 Alleviates Oxygen and Glucose Deprivation/Reoxygenation-Induced Neuronal Injury by Modulating miR-9/SIRT1 Axis in PC12 Cells: Potential Role in Ischemic Stroke

OBJECTIVE

The roles of long non-coding RNA (lncRNAs) in ischemic stroke (IS) have been widely illustrated. Here, we focused on the function and mechanism of lncRNA SNHG7 in IS.

METHODS

Middle cerebral artery occlusion (MCAO) was used for inducing mice to establish IS models in vivo. Oxygen and glucose deprivation/reoxygenation (OGD/R) was used for treating PC12 cells to establish IS models in vitro. Relative expression of SNHG7 and miR-9 was determined by qRT-PCR. The neuronal injury was assessed by measuring relative activity of ROS, malondialdehyde (MDA) level and cell viability. Cell viability was determined by MTT assay. Dual-luciferase reporter (DLR) assay was employed to test the target of SNHG7 or miR-9. Western blot was used to determine the protein expression of SIRT1. Apoptosis rate was measured by flow cytometry.

RESULTS

SNHG7 was down-regulated and miR-9 was up-regulated by MCAO treatment in brain tissues of mice and by OGD/R treatment in PC12 cells. Overexpression of SNHG7 or suppression of miR-9 decreased the relative activity of ROS and the MDA level as well as enhancing cell viability, and SNHG7 reduced apoptosis rate in OGD/R-induced PC12 cells (IS cells). MiR-9 was targeted by SNHG7 and SIRT1 was targeted by miR-9. The protein expression of SIRT1 was reduced by OGD/R treatment in PC12 cells. The suppressive effects of SNHG7 on the relative activity of ROS, the MDA level and apoptosis rate as well as the promotion effect of SNHG7 on cell viability were reversed by miR-9 mimics or sh-SIRT1 in IS cells.

CONCLUSION

LncRNA SNHG7 alleviated OGD/R-induced neuronal injury by mediating miR-9/SIRT1 axis in vitro.