The miR-573/apoM/Bcl2A1-dependent signal transduction pathway is essential for hepatocyte apoptosis and hepatocarcinogenesis
APOPTOSIS
Authors: Hu, Yan-Wei; Chen, Zhi-Ping; Hu, Xiu-Mei; Zhao, Jia-Yi; Huang, Jin-Lan; Ma, Xin; Li, Shu-Fen; Qiu, Yu-Rong; Wu, Xiao-Juan; Sha, Yan-Hua; Gao, Ji-Juan; Wang, Yan-Chao; Zheng, Lei; Wang, Qian
Abstract
Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with an increasing incidence worldwide. Apolipoprotein M (apoM) is a novel apolipoprotein that is mainly expressed in liver and kidney tissues. However, the anti-tumor properties of apoM remain largely unknown. We evaluated the anti-tumor activities and mechanisms of apoM in HCC both in vivo and in vitro. Bioinformatic analysis and luciferase reporter assay results showed that apoM was a potential target of hsa-miR-573 and was downregulated after transfection with hsa-miR-573 mimics. Overexpression of apoM suppressed migration, invasion, and proliferation of hepatoma cells in vitro. Overexpression of hsa-miR-573 in hepatoma cells reduced apoM expression, leading to promotion of the invasion, migration, and proliferation of hepatoma cells in vitro. In addition, hsa-miR-573 markedly promoted growth of xenograft tumors in nude mice with an accompanying reduction in cell apoptosis. ApoM markedly inhibited growth of xenograft tumors in nude mice and promoted cell apoptosis. Moreover, Bcl2A1 mRNA and protein levels were inhibited by apoM overexpression and an increase in apoptosis rate by apoM was markedly compensated by Bcl2A1 overexpression in HepG2 cells. These results provide evidence that hsa-miR-573 promoted tumor growth by inhibition of hepatocyte apoptosis and this pro-tumor effect might be mediated through Bcl2A1 in an apoM-dependent manner. Therefore, our findings may be useful to improve understanding of the critical effects of hsa-miR-573 and apoM in HCC pathogenesis.
Identification of C/EBP beta Target Genes in ALK plus Anaplastic Large Cell Lymphoma (ALCL) by Gene Expression Profiling and Chromatin Immunoprecipitation
PLOS ONE
Authors: Bonzheim, Irina; Irmler, Martin; Klier-Richter, Margit; Steinhilber, Julia; Anastasov, Natasa; Schaefer, Sabine; Adam, Patrick; Beckers, Johannes; Raffeld, Mark; Fend, Falko; Quintanilla-Martinez, Leticia
Abstract
C/EBP beta (CCAAT enhancer binding protein) is a transcription factor that plays a crucial role in survival and transformation of ALK+ anaplastic large cell lymphoma (ALCL). The aim of this study was to identify the downstream targets of C/EBP beta responsible for ALK-mediated oncogenesis. C/EBP beta was knocked down in ALK+ ALCL cell lines with a C/EBP beta-shRNA, followed by gene expression profiling (GEP). GEP analysis revealed a reproducible signature of genes that were significantly regulated by C/EBP beta. Classification into biological categories revealed overrepresentation of genes involved in the immune response, apoptosis and cell proliferation. Transcriptional regulation by C/EBP beta was found in 6 of 11 (BCL2A1, G0S2, TRIB1, S100A9, DDX21 and DDIT4) genes investigated by chromatin immunoprecipitation. We demonstrated that BCL2A1, G0S2 and DDX21 play a crucial role in survival and proliferation of ALK+ ALCL cells. DDX21, a gene involved in rRNA biogenesis, was found differentially overexpressed in primary ALK+ ALCL cases. All three candidate genes were validated in primary ALCL cases by either immunohistochemistry or RT-qPCR. In conclusion, we identified and validated several key C/EBP beta-regulated genes with major impact on survival and cell growth in ALK+ ALCL, supporting the central role of C/EBP beta in ALK-mediated oncogenesis.