Retinoblastoma (RB) is the most common type of malignant intraocular cancer in teenagers. One of the proteins abnormally expressed during oncogenesis of RB is sonic hedgehog (SHH), which possesses the capability to selectively activate transcription factors of different genes. However, the detailed function of SHH in RB remains unknown. Thus, the present study sought to investigate the role of SHH in the development of RB. The human RB WERI-Rb-1 cell line was used as an in vitro model for the knockdown of SHH by a specific short hairpin RNA (shRNA). To assess the effect of SHH inhibition on cell growth and apoptosis, cell viability, colony formation and flow cytometry assays were conducted. WERI-Rb-1 cells transfected with an shRNA targeting SHH were treated with the phosphoinositide-3 kinase (PI3K)/Akt agonist insulin-like growth factor 1 (IGF-1) to investigate the possible mechanism by which SHH promotes RB. The present results revealed that the silencing of SHH induced G1 cell-cycle arrest and apoptosis in WERI-Rb-1 cells and led to a decrease in cell viability, indicating that SHH has a critical role in the determination of RB cell survival. Moreover, according to the results of the IGF-1 assays, suppression of PI3K/Akt was a prerequisite for SHH inhibition, illuminating its potential role in the treatment of RB. The findings outlined in the present study elucidate a clear link between SHH and the PI3K/Akt pathway in RB cell survival, which could provide valuable inspiration for the advancement of therapies against RB.

BackgroundMicroRNAs have been reported to participate in the initiation and progression of retinoblastoma (RB), most common malignancy in children. The refractory mechanisms of chemoresistance and the toxicity of chemotherapies hindered the treatment especially on young children. Novel RB therapies are urgently required. MiR-506 is probed to be associated with the tumorigenesis of various cancers whilst the role of this miR in RB remains unclear.MethodsHere, the impact of miR-506 on RB cell survival in vitro and tumorigenesis in vivo was examined. MiR-506 expression was examined in human RB samples and cell lines as compared with healthy tissues and non-RB cells. EdU staining and colony formation assay were performed to determine the effect of miR-506 on RB cell growth. TdT-mediated dUTP nick end labeling (TUNEL) staining and flow cytometry analysis were applied to detect the apoptotic cell number after miR-506 was downregulated in RB cells. Furthermore, dual-luciferase reporter assay was utilized to confirm the direct interaction between miR-506 and SIRT1 gene.ResultsMiR-506 expression was upregulated in 20 human RB samples from patients as well as in human RB cell lines, WERI-Rb1 and Y79, as compared to that in healthy tissues and non-RB cells. In contrast, the expression of sirtuin 1 (SIRT1), known as NAD-dependent deacetylase, was downregulated in RB samples and cell lines. Aberrant reduced miR-506 expression impaired survival and proliferation of WERI-Rb1 and Y79 cells. The depletion of miR-506 expression promoted apoptosis of the two RB cell lines. The results of bioinformatics analysis and dual-luciferase assay exhibited that miR-506 targeted the 3ʹ-untranslated region of SIRT1 on silencing purpose. The SIRT1 silencing lessened the miR-506 inhibition on RB cell proliferation and undermined apoptosis.ConclusionThe results provided an insight into the role of miR-506 during RB development and offered potential pharmaceutical strategy for RB diagnosis.

Neural injury is associated with the development of diabetic retinopathy. Müller cells provide structural and metabolic support for retinal neurons. High glucose concentrations are known to induce Müller cell activity. Agmatine is an endogenous polyamine, which is enzymatically formed in the mammalian brain and has exhibited neuroprotective effects in a number of experimental models. The aims of the present study were to investigate whether agmatine protects Müller cells from glucose-induced damage and to explore the mechanisms underlying this process. Lactate dehydrogenase activity and tumor necrosis factor-α mRNA expression were significantly reduced in Müller cells exposed to a high glucose concentration, following agmatine treatment, compared with cells not treated with agmatine. In addition, agmatine treatment inhibited glucose-induced Müller cell apoptosis, which was associated with the regulation of Bax and Bcl-2 expression. Agmatine treatment suppressed glucose-induced phosphorylation of mitogen-activated protein kinase (MAPK) protein in Müller cells. The present study demonstrated that the protective effects of agmatine on Müller cells were inhibited by N-methyl-D-aspartic acid (NMDA). The results of the present study suggested that agmatine treatment protects Müller cells from high-concentration glucose-induced cell damage. The underlying mechanisms may relate to the anti-inflammatory and antiapoptotic effects of agmatine, as well as to the inhibition of the MAPK pathway, via NMDA receptor suppression. Agmatine may be of use in the development of novel therapeutic approaches for patients with diabetic retinopathy.