ZNF148 modulates TOP2A expression and cell proliferation via ceRNA regulatory mechanism in colorectal cancer.

Background: Competing endogenous RNA (ceRNA) regulation is a novel hypothesized mechanism that states RNA molecules share common target microRNAs (miRNAs) and may competitively combine into the same miRNA pool. Methods: Zinc finger protein 148 (ZNF148) and TOP2A expression were analyzed in 742 colorectal cancer (CRC) tissues using immunohistochemistry (IHC). ZNF148 mRNA, TOP2A mRNA, miR101, miR144, miR335, and miR365 expression were estimated in 53 fresh frozen CRC tissues by reverse transcription polymerase chain reaction. Mechanisms underpinning ceRNA were examined using bioinformatics, correlation analysis, RNA interference, gene over-expression, and luciferase assays. Results: Protein levels of ZNF148 and TOP2A detected by IHC positively correlated (Spearman correlation coefficient [r(s)]=0.431, P<0.001); mRNA levels of ZNF148 and TOP2A also positively correlated (r=0.591, P<0.001). Bioinformatics analysis demonstrated that ZNF148 and TOP2A mRNA had 13 common target miRNAs, including miR101, miR144, miR335, and miR365. Correlation analysis demonstrated that levels of ZNF148 mRNA were negatively associated with levels of miR144, miR335, and miR365. Knockdown and overexpression tests showed that ZNF148 mRNA and TOP2A mRNA regulated each other in HCT116 cells, respectively, but not in Dicer-deficient HCT116 cells. Luciferase assays demonstrated that ZNF148 and TOP2A regulated each other through 3'UTR. Overexpression of ZNF148 mRNA and TOP2A mRNA caused significant downregulation of miR101, miR144, miR335, and miR365 in the HCT116 cells. We also found that knockdown of ZNF148 and TOP2A significantly promoted cell growth, and overexpression of ZNF148 and TOP2A inhibited cell proliferation, which was abrogated in Dicer-deficient HCT116 cells. Conclusion: ZNF148 and TOP2A regulate each other through ceRNA regulatory mechanism in CRC, which has biological effects on cell proliferation.