We have recently reported that His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 (GHRP-6) synergizes with GH-releasing factor (GRF) to increase GH release and cAMP accumulation in rat pituitary cells in vitro. This study was undertaken to further investigate the mechanism of action of GHRP-6 on GH release, particularly the involvement of protein kinase-C. Forskolin (10(-5) M), A23187 (10(-6) M), and phorbol 12-myristate 13-acetate (PMA; 10(-7) M) all stimulated GH release. However, only PMA can mimic the synergistic effects of GHRP-6 on GRF-stimulated GH release and intracellular cAMP accumulation. 4 alpha-Phorbol 12,13-didecanoate, an inactive phorbol ester, was unable to stimulate GH release or potentiate the effect of GRF. Extracellularly added phospholipase-C not only stimulated GH release in a dose-dependent manner, but also potentiated GRF-induced GH release. Phloretin, a protein kinase-C inhibitor, in a concentration range of 10-250 microM had very little or no effect on basal and GRF-stimulated GH release, but markedly inhibited the stimulatory effects induced by either PMA or GHRP-6. Incubation of rat pituitary cells with 10(-6) M PMA for 24 h completely down-regulated protein kinase-C, since such PMA-pretreated cells did not release GH in response to a second dose of PMA. The protein kinase-C-depleted cells had an attenuated GHRP-6 response, but they responded normally to GRF. Moreover, the synergistic effects of GHRP-6 and GRF on GH release and cAMP accumulation were also greatly inhibited by protein kinase-C down-regulation. These data suggest that the effects of GHRP-6 on GH release, either alone or together with GRF, are at least partially mediated via the activation of protein kinase-C.

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BackgroundLung cancer is the major cause of cancer-related death worldwide, and 80% patients of lung cancer are non-small-cell lung cancer (NSCLC) cases. MicroRNAs are important gene regulators with critical roles in diverse biological processes, including tumorigenesis. Studies indicate that sphingosine kinase 2 (SphK2) promotes tumor progression in NSCLC, but how this occurs is unclear. Thus, we explored the effect of miR-338-3p targeting SphK2 on proliferation and apoptosis of NSCLC cells.MethodsExpression of miR-338-3p and SphK2 in NSCLC A549 and H1299 cell lines was measured using qRT-PCR and Western blot. CCK-8 and colony formation assays were used to assess the effect of miR-338-3p on NSCLC cell line proliferation. Flow cytometry was used to study the effect of miR-338-3p on NSCLC apoptosis. Luciferase reporter assay and Western blot were used to confirm targeting of SphK2 by miR-338-3p. Finally, in vivo tumorigenesis studies were used to demonstrate subcutaneous tumor growth.ResultsmiR-338-3p expression in 34 NSCLC clinical samples was downregulated and this was correlated with TNM stage. miR-338-3p significantly suppressed proliferation and induced apoptosis of NSCLC A549 and H1299 cells in vitro. SphK2 was a direct target of miR-338-3p. Overexpression of miR-338-3p significantly inhibited SphK2 expression and reduced luciferase reporter activity containing the SphK2 3′-untranslated region (3′-UTR) through the first binding site. SphK2 lacking 3′-UTR restored the effects of miR-338-3p on cell proliferation inhibition. miR-338-3p significantly inhibited tumorigenicity of NSCLC A549 and H1299 cells in a nude mouse xenograft model.ConclusionsCollectively, miR-338-3p inhibited cell proliferation and induced apoptosis of NSCLC cells by targeting and down-regulating SphK2, and miR-338-3p could inhibit NSCLC cells A549 and H1299 growth in vivo, suggesting a potential mechanism of NSCLC progression. Therapeutically, miR-338-3p may serve as a potential target in the treatment of human lung cancer.

Long non-coding RNAs (lncRNAs) are key mediators of cancer. The dysregulation of a lncRNA, CASC15, has been linked to several cancers, except lung cancer. Here, the aim of the study was to explore the role and mechanism of CASC15 in lung cancer regulation, with the focus on its interaction with a potential target, microRNA-766-5p (miR-766-5p) and an oncogene, kallikreinrelated peptidase 12 (KLK12). Quantitative real-time PCR (qRT-PCR) was used to assess levels of CASC15, miR-766-5p and KLK12 in lung cancer tissues or cells. Western blot analysis was used to detect KLK12 protein expression. Ectopic expression of CASC15 was induced by a lentiviral system. CCK-8 and transwell assays were used to evaluate lung cancer cell proliferation and invasion, respectively. The interaction among CASC15, miR-766-5p and KLK12 was investigated by bioinformatical analysis and luciferase assay. In lung cancer tissue and cells, CASC15 was upregulated, while miR-766-5p was downregulated. Overexpression of CASC15 promoted lung cancer cell proliferation and invasion. A negative correlation was found between CASC15 and miR-766-5p levels. Overexpression of miR-766-6p reversed the cancer-promoting role of CASC15 in lung cancer cells, which was mediated by KLK12. The tumor-promoting role of CASC15 and tumorsuppressing role of miR-766-5p were also validated in vivo in tumor bearing mice, and KLK12 was also shown as an important mediator. CASC15 promotes lung cancer through the miR-766-5p/ KLK12 axis, indicating that CASC15 is a potential therapeutic in lung cancer.

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BackgroundNon-small cell lung cancer (NSCLC) is the largest histological subgroup of lung cancer and has increased in prevalence in China over the past 5 years. The 5-year survival rate has remained at 15–20 %, with a median survival of 8–12 months. The tumorigenesis and progression of NSCLC is orchestrated by numerous oncogene and anti-oncogene mutations and insights into microRNA function have increased our understanding of the process. Here, we investigated the effects of miR-30b on NSCLC cell invasion and migration and explored the underlying molecular mechanisms involved.MethodsQuantitative reverse transcription PCR, wound healing assay, trans-well assays, western blotting and dual luciferase assays were performed to investigate the molecular mechanisms of miR-30b in NSCLC cells.ResultsMiR-30b was down-regulated and Cthrc1 up-regulated in NSCLC tissues. Both were associated with tumor differentiation, TNM stage and lymph node metastases. Up-regulation of miR-30b restricted A549 and Calu-3 cell invasion and migration. Additionally, the expression of Cthrc1, matrix metalloproteinase-9 and matrix metalloproteinase-2 was reduced, while metallopeptidase inhibitor-1 expression increased. Bioinformatics analysis identified Cthrc1 as a target of miR-30b and western blotting and luciferase reporter assays confirmed that miR-30b regulates Cthrc1 by directly binding to its 3′UTR. Transfection of Cthrc1 without the 3′UTR restored the miR-30b inhibiting cell invasion. Up-regulation of miR-30b or down-regulation of Cthrc1 had potential significance in the invasion and metastasis of NSCLC.ConclusionsMiR-30b was down-regulated and Cthrc1 up-regulated in NSCLC tissues. Both of them were related to tumor differentiation, TNM stage and lymph node metastases. MiR-30b affected NSCLC cells invasion and migration by regulating Cthrc1.

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