Abstract 1095: S100A4 is post-transcriptionally inhibited by miR-505-5p and miR-520c-3p in colorectal cancer

Abstract

Abstract The calcium binding protein S100A4 induces epithelial mesenchymal transition (EMT), migration, invasion, angiogenesis and metastasis. Its induced expression is reported in several cancer types and correlates with poor prognosis. S100A4 is transcriptionally regulated by Sp1, AP1 and CCAAT/enhancer binding protein β transcription factors and its regulation epigenetically controlled by CpG hyper methylation. However, apart from S100A4 functional and transcriptional regulatory aspects, post-transcriptional regulation is not yet elucidated. In this study, we show that specific microRNAs (miR) target the 3’UTR of S100A4. Luciferase-reporter assays with wild-type and mutated miR-505-5p and miR-520c-3p seed sequences of S100A4-3’UTR confirmed the specificity of targeting. Similarly, overexpression of these miRs reduced the S100A4 and inhibition of these miRs function increased the S100A4 protein significantly. Moreover, co-transfection of either S100A4 expressing vector or siRNA-S100A4 along with the miR-505-5p and miR-520c-3p significantly altered the S100A4 mediated migration and invasion in colorectal cancer (CRC) cell lines (p = 0.05). Both these miRs were down-regulated in CRC cell lines and 5 Aza treatment increased these miRs expression and reduced the S100A4 protein amounts. Moreover, in a panel of CRC resected patient tissues (n = 59), miR-520c-3p significantly down regulated (p = 0.03). miR-520c (located in Chr 19, in a big cluster) upstream region was checked for methylation status using methylation specific PCR and combined bisulfite restriction analysis (COBRA) in CRC cell lines, metastatic and non-metastatic CRC resected tissues. We found the upstream promoter region hyper methylated irrespective of metastasis status of patients and in all CRC cell lines checked. 5 Aza treatment of S100A4 less or no expressing cells line Colo206 and Colo320 showed induced miR-520c expression and reduced S100A4 protein in Colo320. Colo206 cells did not show any alternations in expression of S100A4. Taken together, our findings demonstrate that S100A4 is post-transcriptionally regulated by tumor suppressor genes miR-505c and miR-520c and especially miR-520c expression is epigenetically silenced in CRC. Citation Format: Giridhar Mudduluru, Katharina Ilm, Steffen Fuchs, Ulrike Stein. S100A4 is post-transcriptionally inhibited by miR-505-5p and miR-520c-3p in colorectal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1095.