Identification of MicroRNAs Regulated by Isothiocyanates and Association of Polymorphisms Inside Their Target Sites with Risk of Sporadic Colorectal Cancer

Abstract

Sporadic colorectal cancer (CRC) is a typical multifactorial disease. Isothiocyanates (ITC) have been recently shown to inhibit development of CRC in many experimental models. MicroRNAs (miRNAs) are short noncoding RNAs that posttranscriptionally regulate gene expression through binding to 3′ untranslated regions (3′UTR) of target mRNAs. MiRNAs are regulated by natural agents, ITCs included. In our study, using global expression profiling based on TaqMan Low-Density Arrays, we identified 3 common miRNAs (miR-155, miR-23b, miR-27b) regulated by ITCs (sulforaphane, iberin) in colonic epithelial cell lines NCM460 and NCM356. In silico predictions allowed us to find 9 relevant single nucleotide polymorphisms (SNPs) localized within the 3′UTRs of genes (AGTR1, TNFAIP2, PRKCB, HSPA9, RABGAP1, DICER1, ADAM19, VWA5A, and SIRT5) targeted by these ITC-related miRNAs. Finally, we observed that homozygous CC genotype of DICER1, rs1057035, was significantly associated with decreased risk of CRC (odds ratio = 0.49; 95% confidence interval: 0.25–0.95, P = 0.036) when compared to TT homozygote genotype; also, the C allele tended to have a protective effect (P = 0.072). This study showed that miRNAs could be involved in chemoprotective effects of natural agents; their function alteration through SNPs in their binding sites and flanking regions presents a new class of CRC risk factors.

ACKNOWLEDGMENTS

Ondrej Slaby and Milana Sachlova contributed equally to this work. This article was supported by grants from the Internal Grant Agency of Czech Ministry of Health (IGA MZ CR) NS 10352-3/2009, project No. MZ0MOU2005 of the Czech Ministry of Health, and by the project “CEITEC—Central European Institute of Technology” (CZ.1.05/1.1.00/02.0068). The authors would like to thank John B. Smith for proofreading the manuscript.