MiR-148a-regulated Protein Networks in Human Gastric Cancer Cells
Date Issued
2011
Date
2011
Author(s)
Tsai, Sheng-Chueh
Abstract
MicroRNAs (miRNAs) are endogenous small non-coding RNA about 22 nucleotides in length. They can directly bind to target genes, causing down-regulation of their expression post-transcriptionally by suppressing protein translation or degrading mRNA. In this study, we found a tumor suppressor miRNA, miR-148a, could decrease cell growth and metastasis of gastric cancer cells. To further understand the regulatory mechanism of miR-148a in tumor progression of gastric cancer, we used isobaric tags for relative and absolute quantitation (iTRAQ) method to identify differentially expressed proteins in miR-148a-over-expressed AGS cells and construct miR-148a-regulated network. We further analyzed the enriched functions within its network using Ingenuity Pathway Analysis (IPA), STRING 8.3 and TargetScan 5.1 database. Our results revealed that the most enriched biological process was AKT signaling, known as a cell survival-related pathway. We also identified many down-regulated proteins involved in AKT signaling, including Bcl-2-like 1 protein (BCL2L1), Heme oxygenase-1(HMOX1), Integring-linked kinase (ILK) and Glycogen synthase kinase-3 alpha (GSK3A), based on iTRAQ analysis. On the other hand, we identified a predicted target of miR-148a, Fragile X-related protein (FXR1), was down-regulated in miR-148a over-expressed tumor cells. Study reports that down-regulates FXR1 could increase TNFα expression, and cause apoptosis through TNFα. Taken together, these results suggest that miR-148a may suppress cell survival through regulating FXR1-AKT network.
We analyzed microarray data from GEO by using SAM. The RNA expression of MTA2 in tumor tissue is 3.67 times higher than normal tissue. Furthermore, the endogenesis RNA expression of miR-148a in TSGH is 2.91 times higher than in AGS. As we transfect miR-148a precursor into TSGH, the RNA expression of MTA2 is downregulated up to 20%, but luciferase assay data revealed that MTA2 RNA is not the direct target of miR-148a. For further examination, the protein level of MTA2 is decreased 0.93 times under overexpression of miR-148a. MiR-148a might effect the expression of MTA2 in RNA and protein level, and regulate growth and migration ability of TSGH.
Subjects
miRNA
gastric cancer
PI3K/AKT signaling
SDGs
Type
thesis
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