Regulation of ABCG2 expression at the 3' untranslated region of its mRNA through modulation of transcript stability and protein translation by a putative microRNA in the S1 colon cancer cell line

TY - JOUR

T1 - Regulation of ABCG2 expression at the 3' untranslated region of its mRNA through modulation of transcript stability and protein translation by a putative microRNA in the S1 colon cancer cell line

AU - To, Kenneth K. W.

AU - Zhan, Zhirong

AU - Litman, Thomas

AU - Bates, Susan E

PY - 2008

Y1 - 2008

N2 - ABCG2 is recognized as an important efflux transporter in clinical pharmacology and is potentially important in resistance to chemotherapeutic drugs. To identify epigenetic mechanisms regulating ABCG2 mRNA expression at its 3' untranslated region (3'UTR), we performed 3' rapid amplification of cDNA ends with the S1 parental colon cancer cell line and its drug-resistant ABCG2-overexpressing counterpart. We found that the 3'UTR is >1,500 bp longer in parental cells and, using the miRBase TARGETs database, identified a putative microRNA (miRNA) binding site, distinct from the recently reported hsa-miR520h site, in the portion of the 3'UTR missing from ABCG2 mRNA in the resistant cells. We hypothesized that the binding of a putative miRNA at the 3'UTR of ABCG2 suppresses the expression of ABCG2. In resistant S1MI80 cells, the miRNA cannot bind to ABCG2 mRNA because of the shorter 3'UTR, and thus, mRNA degradation and/or repression on protein translation is relieved, contributing to overexpression of ABCG2. This hypothesis was rigorously tested by reporter gene assays, mutational analysis at the miRNA binding sites, and forced expression of miRNA inhibitors or mimics. The removal of this epigenetic regulation by miRNA could be involved in the overexpression of ABCG2 in drug-resistant cancer cells.

AB - ABCG2 is recognized as an important efflux transporter in clinical pharmacology and is potentially important in resistance to chemotherapeutic drugs. To identify epigenetic mechanisms regulating ABCG2 mRNA expression at its 3' untranslated region (3'UTR), we performed 3' rapid amplification of cDNA ends with the S1 parental colon cancer cell line and its drug-resistant ABCG2-overexpressing counterpart. We found that the 3'UTR is >1,500 bp longer in parental cells and, using the miRBase TARGETs database, identified a putative microRNA (miRNA) binding site, distinct from the recently reported hsa-miR520h site, in the portion of the 3'UTR missing from ABCG2 mRNA in the resistant cells. We hypothesized that the binding of a putative miRNA at the 3'UTR of ABCG2 suppresses the expression of ABCG2. In resistant S1MI80 cells, the miRNA cannot bind to ABCG2 mRNA because of the shorter 3'UTR, and thus, mRNA degradation and/or repression on protein translation is relieved, contributing to overexpression of ABCG2. This hypothesis was rigorously tested by reporter gene assays, mutational analysis at the miRNA binding sites, and forced expression of miRNA inhibitors or mimics. The removal of this epigenetic regulation by miRNA could be involved in the overexpression of ABCG2 in drug-resistant cancer cells.

KW - 3' Untranslated Regions

KW - ATP-Binding Cassette Transporters

KW - Base Sequence

KW - Binding Sites

KW - Cell Line, Tumor

KW - Colonic Neoplasms

KW - Drug Resistance, Neoplasm

KW - Gene Expression Regulation, Neoplastic

KW - Genes, Reporter

KW - Humans

KW - Luciferases

KW - MicroRNAs

KW - Models, Genetic

KW - Molecular Sequence Data

KW - Neoplasm Proteins

KW - Nucleic Acid Amplification Techniques

KW - Protein Biosynthesis

KW - RNA Stability

KW - Reproducibility of Results

KW - Sequence Analysis, DNA

U2 - 10.1128/MCB.00331-08

DO - 10.1128/MCB.00331-08

M3 - Journal article

C2 - 18573883

SN - 0270-7306

VL - 28

SP - 5147

EP - 5161

JO - Molecular and Cellular Biology

JF - Molecular and Cellular Biology

IS - 17

ER -