https://orcid.org/0000-0002-9932-8780
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ABSTRACT
Because ADAM17 promotes colonic tumorigenesis, we investigated potential miRNAs regulating ADAM17; and examined effects of diet and tumorigenesis on these miRNAs. We also examined pre-miRNA processing and tumour suppressor roles of several of these miRNAs in experimental colon cancer. Using TargetScan, miR-145, miR-148a, and miR-152 were predicted to regulate ADAM17. miR-143 was also investigated as miR-143 and miR-145 are co-transcribed and associated with decreased tumour growth. HCT116 colon cancer cells (CCC) were co-transfected with predicted ADAM17-regulating miRNAs and luciferase reporters controlled by ADAM17-3’UTR. Separately, pre-miR-143 processing by colonic cells was measured. miRNAs were quantified by RT-PCR. Tumours were induced with AOM/DSS in WT and transgenic mice (Tg) expressing pre-miR-143/miR-145 under villin promoter. HCT116 transfection with miR-145, −148a or −152, but not scrambled miRNA inhibited ADAM17 expression and luciferase activity. The latter was suppressed by mutations in ADAM17-3’UTR. Lysates from colonocytes, but not CCC, processed pre-miR-143 and mixing experiments suggested CCC lacked a competency factor. Colonic miR-143, miR-145, miR-148a, and miR-152 were downregulated in tumours and more moderately by feeding mice a Western diet. Tg mice were resistant to DSS colitis and had significantly lower cancer incidence and tumour multiplicity. Tg expression blocked up-regulation of putative targets of miR-143 and miR-145, including ADAM17, K-Ras, XPO5, and SET. miR-145, miR-148a, and miR-152 directly suppress colonocyte ADAM17 and are down-regulated in colon cancer. This is the first direct demonstration of tumour suppressor roles for miR-143 and miR-145 in an in vivo model of colonic tumorigenesis.
Acknowledgments
Grant Support: This work was supported by the National Institutes of Health Grants [R01 CA164124-01 and R01 CA180087-01 (YCL), R01 CA226303 (TCH)] and the Samuel Freedman GI Cancer Laboratory Fund at the University of Chicago and the University of Chicago Cancer Research Foundation (UCCRF) Women’s Board. The transgenic mouse was created by The Transgenic Mouse Core at the University of Chicago that receives financial support from NIH NCI Cancer Center Support Grant P30CA014599.
The miR-143 and miR-145 null mice were generously provided by Dr Eric Olson, Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
Disclosure statement
The authors disclose that they have no potential conflict of interest.
Supplementary material
Supplemental data for this article can be accessed here.
Abbreviations
| ADAM17 | = | A Disintegrin and Metalloproteinase17 |
| AOM | = | Azoxymethane |
| CCC | = | Colon cancer cells |
| DSS | = | Dextran sulphate sodium |
| EGFR | = | Epidermal growth factor receptor |
| EV | = | Empty vector |
| IHC | = | Immunohistochemistry |
| Scr | = | Scrambled control |
| Tg | = | Transgene |
| XPO5 | = | Exportin5 |
| SET | = | Nuclear proto-oncogene |
| 3’-UTR | = | Three prime untranslated region |
| WT | = | Wild type |
