BackgroundMalignant glioma is the most devastating and aggressive tumour in the brain and is characterised by high morbidity, high mortality and extremely poor prognosis. The main purpose of the present study was to investigate the effects of schisandrin B (Sch B) on glioma cells both in vitro and in vivo and to explore the possible anticancer mechanism underlying Sch B-induced apoptosis and cell cycle arrest.MethodsThe anti-proliferative ability of Sch B on glioma cells were assessed by MTT and clony formation assays. Flow cytometric analysis was used to detect cell cycle changes. Apoptosis was determined by Hoechst 33342 staining and annexin V/PI double-staining assays. The mitochondrial membrane potential was detected by Rhodamine 123 staining. The in vivo efficacy of Sch B was measured using a U87 xenograft model in nude mice. The expressions of the apoptosis-related and cell cycle-related proteins were analysed by western blot. Student’s t-test was used to compare differences between treated groups and their controls.ResultsWe found that Sch B inhibited growth in a dose- and time-dependent manner as assessed by MTT assay. In U87 and U251 cells, the number of clones was strongly suppressed by Sch B. Flow cytometric analysis revealed that Sch B induced cell cycle arrest in glioma cells at the G0/G1 phase. In addition, Sch B induced glioma cell apoptosis and reduced mitochondrial membrane potential (ΔΨm) in a dose-dependent manner. Mechanically, western blot analysis indicated that Sch B induced apoptosis by caspase-3, caspase-9, PARP, and Bcl-2 activation. Moreover, Sch B significantly inhibited tumour growth in vivo following the subcutaneous inoculation of U87 cells in athymic nude mice.CoclusionsIn summary, Sch B can reduce cell proliferation and induce apoptosis in glioma cells and has potential as a novel anti-tumour therapy to treat gliomas.

To date, the management of dopamine agonist (DA)-resistant prolactinomas remains a major clinical problem. Previously, we determined that miRNA-93 expression increases in DA-resistant prolactinomas; however, the role of miRNA-93 in the DA resistance remains largely unexplored. Hence, this study aimed to investigate the susceptibility of tumor cells to cabergoline (CAB) and the autophagy changes in MMQ and GH3 cells after miRNA-93 overexpression or inhibition. We used bioinformatics to identify the potential target of miRNA-93. Subsequently, we analyzed the correlation between miRNA-93 and autophagy-related 7 (ATG7) using protein expression analysis and luciferase assays. Furthermore, the change in the effect of miRNA-93 was measured after ATG7 overexpression. miRNA-93 expression was elevated in DA-resistant prolactinomas, whereas the expression of its identified target, ATG7, was downregulated. miRNA-93 overexpression suppressed the cytotoxic effect of CAB in MMQ and GH3 cells. In contrast, miRNA-93 downregulation enhanced CAB efficiency and promoted cell autophagy, eventually resulting in apoptosis. These results were further confirmed in in vivo xenograft models in nude mice. ATG7 overexpression could reverse the inhibitory effect of miRNA-93 on CAB treatment. Taken together, our results suggest that miRNA-93 mediates CAB resistance via autophagy downregulation by targeting ATG7 and serves as a promising therapeutic target for prolactinoma.

Abstract.Little is known about the function of microRNAs in prolactinomas treated with bromocriptine. The aim of the study was to explore the microRNAs associated with bromocriptinetreated prolactinomas. Six prolactinoma samples were selected according to whether they received bromocriptine treatment or not before microsurgery, and microRNA expression profiles of bromocriptine-treated and untreated prolactinomas were screened by the miRCURY LNA Array. The differentially expressed microRNAs in microarrays were further validated by stem-loop real-time PCR and subjected to gene ontology analysis and KEGG pathway analysis. In addition, related genes of microRNAs were analyzed by qRT-PCR in 15 prolactinoma samples. The initial analysis by microarrays generated a list of 80 upregulated microRNAs and 71 downregulated microRNAs in treated prolactinomas compared to untreated prolactinomas. miR-206, miR-516b and miR-550 were confirmed to be significantly upregulated, while miR-671-5p was confirmed to be significantly downregulated in treated prolactinomas by qRT-PCR. microRNA-mRNA network analysis integrating GO and KEGG pathway annotation displayed some critical factors. Platelet-derived growth factor α polypeptide (PDGFA) and bone morphogenetic protein 4 (BMP4), were verified to be differentially expressed between the two groups. PDGFA was significantly upregulated in treated prolactinomas, while BMP4 was significantly downregulated in treated prolactinomas. Our study reveals differential expression of microRNAs in prolactinoma after pharmacotherapy. Specific microRNAs may be involved in the inhibition or promotion of prolactinoma tumor growth impacted by bromocriptine pharmacotherapy. PDGFA and BMP4 may be involved in the pharmacotherapy mechanism of prolactinoma. IntroductionDopamine agonist medication is a first-line therapy in the treatment of prolactinomas. Bromocriptine can normalize the serum prolactin (PRL) level in more than 90% of cases and reduce tumor volume in approximately 85% of cases (1). Its primary mechanism of action is through the dopamine 2 (D2) receptor on the cell membrane of prolactin cells, which is selectively activated. Thus, the transcription and expression of the PRL gene and the metabolism of prolactin cells are inhibited, leading to decreased synthesis and secretion of PRL. In addition, the involution of the endoplasmic reticulum and Golgi apparatus, and the suppression of cell proliferation lead to a reduction in tumor volume (2). The subsequent pharmacotherapeutic effect of prolactinoma acts through the TGF-β and MAPK signaling pathway to inhibit lactotroph cell proliferation and induce apoptosis through D2 receptors (3-5).microRNAs are approximately 22 nucleotide, non-coding RNA generated from endogenous hairpin-shaped transcripts which post-transcriptionally regulate the expression of protein-coding genes (6) and are thought to be involved in several cellular processes regulating differentiation and development (7,8). microRNAs may regulate gene expression at the post-transcriptional l...

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Dopamine receptor agonists (DAs) can reduce hormone release and tumor mass in the majority of prolactinomas, whereas such effects are controversial in clinically nonfunctioning pituitary adenomas (NFPAs). Whether expression of dopamine 2 receptor (D2R) is different in subgroups of NFPAs has not been fully elucidated. We assessed and compared D2R subtype (long: D2L and short: D2S) mRNA levels in subgroups of NFPAs by real-time reverse transcriptase polymerase chain reaction (RT-PCR). For both D2L and D2S mRNA, there were no significant differences among them. Only 21.6% of NFPAs showed relatively high D2R mRNA levels; furthermore, histopathological subtypes of those cases with relatively high D2R expression were gonadotropinomas and null-cell adenomas. These data suggest that DAs are effective only for a small proportion of NFPAs, and relatively high D2R expression may more possibly happen to a subset of gonadotropinomas and null-cell adenomas.