Expression of miR-204 in pediatric retinoblastoma and its effects on proliferation and apoptosis of cancer cells

P38 Mitogen-Activated Protein Kinase Protects Against Retinoblastoma Through Regulating USP22/SIRT1/SOST Axis

Retinoblastoma (RB) is the most common intraocular malignancy in children. It has been previously reported that p38 MAPK is related to the pathogenesis of RB. Here we aim at investigating how p38 MAPK affected RB progression through mediating USP22/SIRT1/SOST axis. In this study, Thirty-two cases of RB and normal retinal tissues were collected. The expression of p38 MAPK, phosphorylation of p38 MAPK (P-p38 MAPK), USP22, SIRT1 and SOST in clinical tissues and cells was measured using RT-qPCR, IHC assay or western blot analysis. Cell proliferation was detected by CCK-8. Apoptosis rate of cells was examined by flow cytometry. Cell migration was evaluated using scratch test. Cell invasion ability was examined by Transwell assay. Co-immunoprecipitation (CO-IP) was utilized to measure the deubiquitination of USP22 on SIRT1. In vivo, mice were respectively injected with plasmids and the tumor growth as well as the tumor weight were detected. Results showed that p38 MAPK, P-p38 MAPK and SOST were poorly expressed in RB tissues and cells whereas USP22 and SIRT1 were overly expressed. P-p38 MAPK inhibited the expression of USP22, and overexpression of USP22 eliminated the inhibitory roles of P-p38 MAPK on tumor growth, as well as cell proliferation, migration and invasion. USP22 stabilized and promoted the expression of SIRT1 through its deubiquitination function. Silencing the expression of SIRT1 contributed to boosted expression of SOST, thus suppressing the growth of tumor cells. Collectively, the phosphorylation of p38 MAPK regulates the SIRT1/SOST axis to protect against RB via silencing USP22. The findings present some cues for a further approach to RB.

Autophagy-related gene 7 deficiency caused by miR-154-5p overexpression suppresses the cell viability and tumorigenesis of retinoblastoma by increasing cell apoptosis

Background

Retinoblastoma is a rare cancer of the retina that accounts for 3% of all childhood cancers. The aim of this study was to illuminate the oncogenic role and potential molecular mechanisms of the microRNA miR-154-5p and autophagy-related gene 7 (ATG7) in retinoblastoma, and to establish a nude mouse model in order to explore new therapeutic horizons for the disease.

Methods

Quantitative reverse transcription-polymerase chain reaction and western blot were performed to detect the expression levels of miR-154-5p and ATG7. The targeting relationship between miR-154-5p and ATG7 was analyzed by employing the luciferase reporter assay. MiR-154-5p mimic and pcDNA-ATG7 were transfected, either alone or in combination, into Y79 cells. The subsequent in vitro experiments involved four groups: the control group, miR-154-5p group, ATG7 group, and miR-154-5p + ATG7 group. Orthotopic xenograft models were established by injecting BALB/c athymic nude mice with treated and untreated Y79 cells.

Results

Y79 cells were transfected with miR-NC or miR-154-5p. Compared to those in the control group, the mRNA expression levels of miR-154-5p were increased in the miR-154-5p mimic group; in contrast, decreases were observed in the mRNA and protein expression levels of ATG7. Y79 cells were transfected with PcDNA or pcDNA-ATG7. The mRNA expression level of ATG7 was increased in pcDNA-ATG7 group. MiR-154-5p was found to have an element complementary to the three prime untranslated region of ATG7. Overexpression of miR-154-5p inhibited Y79 cells proliferation and migration, and promoted Y79 cells apoptosis via targeting of ATG7. In the in vivo experiment, the tumors of the miR-154-5p group of mice were significantly reduced in weight. Tumor growth and the protein levels of Survivin were both suppressed when miR-154-5p was overexpressed in vivo; however, cell apoptosis and the protein levels of p21 were promoted. In the miR-154-5p group, the expression levels of miR-154-5p were upregulated compared to those in the control group, but the ATG7 expression level was downregulated.

Conclusions

MiR-154-5p overexpression downregulated ATG7, which inhibited cell proliferation and apoptosis in vitro, as well as tumor formation in vivo.

LINC00202 promotes retinoblastoma progression by regulating cell proliferation, apoptosis, and aerobic glycolysis through miR-204-5p/HMGCR axis

LINC00202 is a newly identified long noncoding RNA (lncRNA) and has been demonstrated to involve in the progression of retinoblastoma (RB). Here, we further explored the role and the underlying molecular mechanism of LINC00202 on RB malignant properties and glycolysis. LINC00202, microRNA (miR)-204-5p, and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) mRNA were detected by a quantitative real-time polymerase chain reaction. Cell proliferation and apoptosis were analyzed using cell counting kit-8 assay and colony formation assay and flow cytometry, respectively. Glucose metabolism was calculated by measuring the extracellular acidification rate (ECRA). Western blot was used to detect the levels of HMGCR, ki67, pro-caspase-3, cleaved-caspase-3, and lactate dehydrogenase A chain (LDHA). The interaction between miR-204-5p and LINC00202 or HMGCR was analyzed by the dual-luciferase reporter assay. Murine xenograft model was established to conduct in vivo experiments. LINC00202 expression was upregulated in RB tumor tissues and LINC00202 knockdown inhibited RB cell proliferation, glycolysis, and stimulated apoptosis in vitro as well as impeded tumor growth in vivo. MiR-204-5p directly bound to LINC00202 and HMGCR in RB cells, and LINC00202 functioned as a competing endogenous RNA in regulating HMGCR through competitively binding to miR-204-5p. More importantly, the regulation of malignant properties and glycolysis of RB cells mediated by LINC00202 could be reversed by abnormal miR-204-5p or HMGCR expression in RB cells. In all, LINC00202 promoted RB cell proliferation, glycolysis, and suppressed apoptosis by regulating the miR-204-5p/HMGCR axis, suggesting a novel therapeutic target for patients with RB.