title: MACC1 is post-transcriptionally regulated by miR-218 in colorectal cancer.
abstract: Metastasis is a multistep molecular network process, which is lethal for more than 90% of the cancer patients. Understanding the regulatory functions of metastasis-inducing molecules is in high demand for improved therapeutic cancer approaches. Thus, we studied the post-transcriptional regulation of the crucial carcinogenic and metastasis-mediating molecule metastasis associated in colon cancer 1 (MACC1). In silico analysis revealed MACC1 as a potential target of miR-218, a tumor suppressor miRNA. Expression of these two molecules inversely correlated in colorectal cancer (CRC) cell lines. In a cohort of CRC patient tissues (n = 59), miR-218 is significantly downregulated and MACC1 is upregulated compared with normal mucosa. Luciferase reporter assays with a construct of the MACC1-3'-UTR harboring either the wild type or the mutated miR-218 seed sequence confirmed the specificity of the targeting. miR-218 inhibited significantly MACC1 protein expression, and consistently, MACC1-mediated migration, invasion and colony formation in CRC cells. Anti-miR-218 enhanced the MACC1-mediated migration, invasion and colony formation. Similar findings were observed in the gastric cancer cell line MKN-45. Further, we performed methylation-specific PCR of the SLIT2 and SLIT3 promoter, where miR-218 is encoded in intronic regions. The SLIT2 and SLIT3 promoters are hypermethylated in CRC cell lines. miR-218 and SLIT2 expressions correlated positively. Methyltransferase inhibitor 5-Azacytidine induced miR-218 expression and inhibited the expression of its target MACC1. We also determined that MACC1 has alternative polyadenylation (APA) sites, which results in different lengths of 3'-UTR variants in a CRC cell line. Taken together, miR-218 is post-transcriptionally inhibiting the MACC1 expression and its metastasis-inducing abilities.
authors.affiliation: Experimental and Clinical Research Center, Charité University Medicine Berlin and Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Ilm
authors.affiliation: Experimental and Clinical Research Center, Charité University Medicine Berlin and Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Fuchs
authors.affiliation: Experimental and Clinical Research Center, Charité University Medicine Berlin and Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.
authors.forename: Giridhar
authors.initials: G
authors.lastname: Mudduluru
authors.affiliation: Experimental and Clinical Research Center, Charité University Medicine Berlin and Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Stein
mesh_terms: D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D015534:Trans-Activators; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: C544162:MACC1 protein, human; C547471:MIRN218 microRNA, human; D035683:MicroRNAs; D015534:Trans-Activators; D014157:Transcription Factors
keywords: MACC1; alternative polyadenylation; colorectal cancer; epigenetic regulation; miR-218