New Findings r What is the central question of this study?Aquaporins have been shown to play an important role in tumour development. It is not known whether short-hairpin RNA targeting aquaporin 3 (AQP3) shows antitumour effects in experimental non-small cell lung cancer (NSCLC). r What is the main finding and its importance?Knockdown of AQP3 suppressed tumour growth and reduced angiogenesis in human NSCLS xenografts. Aquaporin 3 could thus be envisaged as a novel therapeutic target for NSCLC.Non-small cell lung cancer (NSCLC) is one of the most common diseases encountered in medical oncology practice. The aim of the present study was to test the antitumour effects of short-hairpin RNA targeting aquaporin 3 (AQP3) in experimental NSCLC. Expression of AQP3 was suppressed in human A549 and H1299 NSCLC cell lines by short-hairpin RNA-mediated silencing. Therapeutic effects were assessed by examining tumorigenicity using a subcutaneous xenograft mouse model of NSCLC. Aquaporin 3 knockdown inhibited tumour growth and prolonged survival of mice with tumours. Aquaporin 3 knockdown suppressed tumour proliferation, marked by enhanced expression of p53, an increased ratio of cleaved caspase 3 to pro-caspase 3 and reduced expression of proliferating cell nuclear antigen and B-cell lymphoma-2 (bcl-2). Aquaporin 3 knockdown inhibited tumour angiogenesis, marked by decreased CD31 immunostaining and reduced expression of hypoxia-inducible factor-2α and vascular endothelial growth factor. Aquaporin 3 knockdown reduced cellular glycerol content and suppressed mitochondrial ATP formation. Aquaporin 3 knockdown in vitro significantly suppressed activities of matrix metalloproteinases MMP2 and MMP9, reduced AKT phosphorylation and decreased cell invasiveness of A549 and H1299 cells. In conclusion, AQP3 knockdown suppressed tumour growth and reduced angiogenesis in human NSCLS xenografts. Aquaporin 3 could thus be envisaged as a novel therapeutic target for NSCLC.
Previous studies reported that astrocyte response to amyloid-β (Aβ) before obvious neuronal damage could be detected in Alzheimer's disease (AD). It is suggested that astrocytes play a key role in AD pathologies. In this study, we investigated the effects of Aβ(42) oligomer on the proliferation and activation of astrocytes by in vitro experiments. The results showed that Aβ(42) oligomers could convert astrocytes to responsive astrocytes. It was revealed by MTT and ELISA assays that the viability of astrocytes gradually decreased, and the release of brain-derived neurotrophic factor increased with elevated Aβ(42) concentration and prolonged duration. Reverse-transcription polymerase chain reaction (RT-PCR) assay indicated that Aβ(42) oligomers increased the expression of glial fibers acid protein and interleukin-1β in a dose-dependent but not time-dependent manner. It was showed that A8, a mouse monoclonal antibody, was able to protect the cultured astrocytes against the toxicity of Aβ(42) oligomers. The result demonstrated that A8 could inhibit Aβ(42) oligomers toxic effects on astrocytes and that, alone, A8 could promote the proliferation of astrocytes in certain time. The present study laid a theoretical foundation for further understanding the effects of Aβ(42) on astrocytes and, hence, is conducive to the theoretical understanding and clinical therapies of AD progression.
Abstract. Non-small cell lung cancer (NSCLC) has a high mortality rate and poor prognosis. The aim of the present study was to silence EZH2 and explore the antitumor effect of small interfering RNA (siRNA)-EZH2 in combination with radiotherapy, which is a main treatment for NSCLC. The results showed that irradiation in the presence of siRNA-EZH2 arrested A549 cells in the G 0 and G 1 phases, delayed cell cycle progression and effectively inhibited cell proliferation, compared with cells that received radiotherapy alone. The combined therapy enhanced the percentage of apoptotic A549 cells in vitro and reduced the tumor size, in addition to increasing the survival rate in tumor xenograft experiments. This study demonstrates the antitumor activity of ionizing radiation therapy in combination with siRNA-EZH2 in NSCLC, both in vitro and in vivo, as well as providing a scientific rationale for targeting EZH2 to enhance the sensitivity of cancer to radiotherapy in NSCLC patients.
Nonsmall-cell lung cancer has a high mortality rate and poor prognosis. In the present study, we silenced EZH2 and explored the consequent cell cycle changes. The expression of cell-cycle-related proteins, including p53, p21, Cdc2, and cyclin B1, was detected with western blotting, and the cell cycle distribution was determined with flow cytometry. Inhibition of EZH2 expression changed the cell cycle distribution, in particular inducing G2/M arrest. Expression of Cdc2 and cyclin B1 was significantly decreased in A549 and HTB-56 cells after EZH2-siRNA treatment. In addition, p53 expression was increased by 21% and 18%, and p21 expression was increased by 31% and 23%, in A549 and HTB-56 cells, respectively, in the presence of EZH2-siRNA. This study clearly demonstrates that modulation of EZH2 expression with siRNA affects the cell cycle and the expression levels of p53 and p21, thereby changing cyclin B1 and Cdc2 expression and inducing G2/M arrest. These results may explain the observed antitumor activity of EZH2 silencing. Such explorations of the molecular mechanism of EZH2 will help us develop novel approaches to the diagnosis, treatment, and prevention of nonsmall-cell lung cancer.
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