Ples (Pearson correlation value = 0.94, P = 0.001). However, no significant linear relationship was
Ples (Pearson correlation value = 0.94, P = 0.001). However, no significant linear relationship was found in normal samples (Pearson correlation value = -0.45, P = 0.27). The specific data forexpression levels of ANGPTL1 and miR-138 in tumor tissues are plotted in Additional file 5: Figure S3A. The level of miR-138 was further determined in cells with ANGPTL1 overexpression and knockdown. As shown in Additional file 5: Figure S3B, overexpression of ANGPTL1 significantly enhanced miR-138 expression by 1.51-fold (P < 0.0001), whereas miR-138 level was markedly (86 ) inhibited by knockdown of ANGPTL1 (P < 0.0001), indicating that ANGPTL1 may regulate the expression of miR-138. Then, we conducted transwell migration assay to determine whether miR-138 is involved in ANGPTL1-mediated inhibition of migration of CRC cells. Cells were transiently transfected with a miR-138 inhibitor, mimics or negative controls at 50 nmol/l using Lipofectamine 2000. As shown in Fig. 5a-b, SW620-Ctrl cells treated with miR-138 inhibitor showed enhanced migratory capacity (P = 0.01), and miR-138 inhibitor reversed the inhibition of migration in SW620-ANGPTL1 cells (P = 0.001). In addition, in SW480-shANGPTL1 cells transfected with miR-138 mimics, the shANGPTL1induced increase in migratory capacity was significantly attenuated (P = 0.006, Fig. 5c-d). These findings suggest that ANGPTL1 directly or indirectly up-regulates the expression of miR-138, and miR-138 is involved in ANGPTL1-mediated inhibition of migration of CRC cells.Discussion In this study, we compared the gene expression profiles of paired cancerous PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27597769 and normal tissues from TCGA datasets, and identified ANGPTL1 as a down-regulated gene in CRC. Further in vitro and in vivo studies confirmed that ANGPTL1 inhibited migration and invasion with limited effects on CRC cell proliferation and colony formation of CRC cells. Finally, we found that ANGPTL1 exerts its effect by up-regulating miR-138. This study is the first to investigate the role of ANGPTL1 in the biology and progression of CRC. Similar to our results, previous studies have reported that ANGPTL1 was significantly decreased in lung [7, 18] and breast [7] tumor tissues compared to normal tissues. In addition, the inhibition of migration in CRC wasChen et al. Journal of Experimental Clinical Cancer Research (2017) 36:Page 10 ofFig. 4 a Heatmap illustrating the diversity of miRNA levels among 8 samples with the lowest ANGPTL1 mRNA level and 8 samples with the EPZ004777 site highest ANGPTL1 mRNA level. Among the miRNAs, the level of miR-138 was significantly higher in the samples with high levels of ANGPTL1 (P = 0.01). b Level of miR-138 in cells with overexpression and knockdown of ANGPTL1. In SW620-ANGPTL1 cells, the expression of miR-138 was significantly enhanced compared to control cells (P < 0.0001), while it was markedly inhibited in SW480-shANGPTL1 cells (P < 0.0001)consistent with the conclusions of a study by Kuo et al.[7], in which ANGPTL1 was reported to inhibit the migration and invasion of lung and breast cancer cells via mesenchymal-epithelial transition. Together, these studies congruously characterized ANGPTL1 as a tumor suppressor gene in cancer. miRNAs are involved in post-transcriptional and translational silencing of target genes by binding to complementary sequences in 3' UTRs [19]. Therefore, miRNAs are crucial in the regulation of many crucial biological processes, such as detachment, migration, invasion and colonization of cancer cells [20,.
