MAP4K4 Knockout Cell Lysate

Although conventional clinical treatment with low LET (linear energy transfer) including gamma-ray and X-ray has been widely used for radiotherapy in various cancers, however, ineffective outcomes occur due to radioresistance caused by p53 mutation. High LET has become alternative since it is able to induce apoptosis regardless of p53 status. Indeed, the molecular mechanisms toward high LET have been suggested. Nevertheless, most studies have been done in monolayer culture system which cannot promptly represent solid tumor microenvironment. Here we applied in vivo mimic 3D spheroid to conduct microarray-based genomic expression and molecular signaling pathway analyses under neutron irradiation. As a result, 3D spheroid system was achieved using thermorevesible gel system. An effective apoptosis-inducible dose of neutron was determined by Acridine Orange (AO) staining in 3D spheroid. Differentially expressed genes in both unique and common responses to neutron were identified in the 3D spheroid compared to the monolayer cells. Total 95 and 169 genes were notably altered at transcription level toward neutron in monolayer and 3D spheroid system, respectively. Based on microarray data, putative apoptosis signaling was depicted using Pathway Studio software. In 3D-in vivo mimic model, the molecular networks interacted with ITGB1, MAP4K4, PAPPA, and SGK1 might be suggested as plausible molecular pathways. In conclusion, we demonstrate novel molecular signaling and corresponding targets of in vitro solid tumor following high LET exposure. This result might provide critical clues for clarification of neutron-induced apoptosis mechanism.

miRNAs are associated with various types of cancer due to their ability to affect expression of genes that modulate tumorigenesis. In this study, we explored the role of miR-141 in pancreatic cancer. The analysis of clinical characteristics showed that miR-141 was significantly downregulated in tissues and cell lines of pancreatic cancer. Moreover, the decreased miR-141 level was significantly associated with tumor size and TNM stage, as well as lymph node and distant metastasis. Meanwhile, both Kaplan-Meier and multivariate survival analysis showed decreased miR-141 were associated with overall survival. Overexpression of miR-141 in pancreatic cancer cells inhibited cell proliferation, clonogenicity, and invasion; induced G(1) arrest and apoptosis; and enhanced chemosensitivity. To understand how miR-141 mediates the phenotype of pancreatic cancer cells, a bioinformatics tool was used to identify MAP4K4 as a potential target of miR-141. The Dual-Luciferase reporter gene assay showed that miR-141 binds directly to the 3'-untranslated region (3'UTR) of MAP4K4 to inhibit MAP4K4 expression. Western blot and quantitative real-time PCR (qRT-PCR) analyses revealed that MAP4K4 expression was inversely correlated with miR-141 expression both in pancreatic cancer samples and cell lines. Knockdown of MAP4K4 inhibited cell proliferation, clonogenicity, and invasion, induced G(1) arrest and apoptosis, and enhanced chemosensitivity. In a nude mouse xenograft model, both overexpression of miR-141 and knockdown of MAP4K4 significantly repressed pancreatic cancer cell growth. Therefore, we conclude that miR-141 targets MAP4K4, acts as a tumor suppressor in pancreatic cancer cells, and may serve as a novel therapeutic agent for miRNA-based pancreatic cancer therapy. (C) 2013 AACR.