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Recent studies have reported the important roles of dopamine receptors in the early development and progression of glioblastoma (GBM). The present research aimed to explore the antineoplastic effect and intrinsic pathways of action of dopamine receptor D1 agonist SKF83959 on GBM cells. Flow cytometric analysis revealed a significant level of apoptotic cell death under SKF83959 treatment. SKF83959 administration increased intracellular calcium levels and oxidative stress through the phospholipase C/inositol trisphosphate pathway. The downstream calpains were activated and dysregulated by the increased calcium levels. The mitochondrial membrane potential‑dependent staining assay revealed decreased mitochondrial transmembrane potential in GBM cells under SKF83959 treatment. The mitochondrial/cytosolic fraction and western blotting further demonstrated mitochondrial dysfunction and endoplasmic reticulum stress, followed by apoptosis. The calpain inhibitor, calpastatin, significantly reversed the increase in mitochondrial injury and endoplasmic reticulum stress and eventually ameliorated GBM cell apoptosis during SKF83959 treatment. Finally, the in vivo inhibitory efficacy of SKF83959 was verified in GBM xenograft models. In addition, immunohistochemistry and western blotting both revealed increased expression of calpains in xenograft GBM tissues. These results suggested a potential therapeutic target for human GBM treatment regarding calpain expression and activity regulation.

Purpose: Recent studies have reported important roles of dopamine receptors in the early development and progression of glioblastoma (GBM). Here, we tested the antitumor activity of a Dopamine receptor D1 (DRD1) agonist, either alone or in combination with temozolomide (TMZ) on GBM cells., Methods: Immunofluorescence, immunohistochemistry and Western blotting were used to detect dopamine receptor expression in primary human GBM tissues. In addition, clinical data of GBM patients downloaded from The Cancer Genome Atlas (TCGA) were analyzed. Image-based tracking analysis of LC3 using a mCherry-eGFP-LC3 plasmid was utilized to monitor autophagic flux. Transmission electron microscopy (TEM) was used to visualize aggregation of autophagosomes/autolysosomes. Finally, DRD1 agonist (SKF83959)-induced inhibition of GBM growth was assessed in vitro and in vivo., Results: Positive DRD1 expression was observed in human GBM tissues and found to be related with a good clinical outcome. DRD1 activation specifically inhibited GBM cell growth and significantly disrupted autophagic flux, which led to tumor cell death. Moreover, we found that DRD1 agonist treatment inhibited auto-lysosomal degradation in GBM cells and that this process was calcium overload dependent and related to inhibition of mammalian target of rapamycin (mTOR). Finally, we found that DRD1 agonist and TMZ co-treatment yielded a synergistic therapeutic effect both in vivo and in vitro., Conclusions: From our data we conclude that DRD1 activation inhibits GBM cell growth and may serve as an alternative avenue for the design of future GBM therapies.

Ribosomal protein s15a (RPS15A), a highly conserved cytoplasmic protein, promotes mRNA/ribosome interaction in translation. Recent evidence showed that RPS15A is essential for tumor growth. RPS15A expression level was measured in glioblastoma tissue samples and normal brain (NB) tissue samples. RPS15A RNAi stable cell line U87 and U251 was generated by the pLVTHM-GFP lentiviral RNAi expression system. The knockdown efficiency was confirmed by quantitative real-time PCR and western blot. Molecular mechanisms and the effect of RPS15A on cell growth and migration were investigated by using western blot, MTT assay, wound healing assay, transwell migration assay, and tumorigenesis in nude mice. Here, we report that RPS15A is overexpressed in human glioblastoma tumor tissues. RPS15A knockdown inhibits proliferation and migration of glioblastoma cells in vitro. Knocking down RPS15A leads to the level of p-Akt decrease and cell cycle arrested in G0/G1 phase in U87 and U251 cells. Furthermore, the growth of glioblastoma cell-transplanted tumors in nude mice is inhibited by transduction with Lv-shRPS15A. Our findings indicate that RPS15A promotes cell proliferation and migration in glioblastoma for the first time. RPS15A might play a distinct role in glioblastoma and serve as a potential target for therapy.

Ribosomal protein s15a (RPS15A), a highly conserved cytoplasmic protein, promotes mRNA/ribosome interaction in translation. Recent evidence showed that RPS15A is essential for tumor growth. RPS15A expression level was measured in glioblastoma tissue samples and normal brain (NB) tissue samples. RPS15A RNAi stable cell line U87 and U251 was generated by the pLVTHM-GFP lentiviral RNAi expression system. The knockdown efficiency was confirmed by quantitative real-time PCR and western blot. Molecular mechanisms and the effect of RPS15A on cell growth and migration were investigated by using western blot, MTT assay, wound healing assay, transwell migration assay, and tumorigenesis in nude mice. Here, we report that RPS15A is overexpressed in human glioblastoma tumor tissues. RPS15A knockdown inhibits proliferation and migration of glioblastoma cells in vitro. Knocking down RPS15A leads to the level of p-Akt decrease and cell cycle arrested in G0/G1 phase in U87 and U251 cells. Furthermore, the growth of glioblastoma cell-transplanted tumors in nude mice is inhibited by transduction with Lv-shRPS15A. Our findings indicate that RPS15A promotes cell proliferation and migration in glioblastoma for the first time. RPS15A might play a distinct role in glioblastoma and serve as a potential target for therapy. [ABSTRACT FROM AUTHOR]