RNA stability regulates differential expression of the metastasis protein, osteopontin, in hepatocellular cancer.

Journal Article (Journal Article)

BACKGROUND: Osteopontin (OPN) is a potential therapeutic target in hepatocellular carcinoma (HCC), because it is a critical mediator of metastatic function. The molecular mechanisms that determine expression of OPN in HCC, however, are unknown. In this study, we examine differential OPN expression in the 2 HCC cell lines: HepG2 and Hep3B. METHODS: OPN expression, metastatic function, OPN promoter activity, and active transcription of OPN mRNA and its decay were assessed in the 2 HCC cell lines using standard techniques. RNA gel-shift assays were performed to determine binding of cytoplasmic proteins to OPN mRNA. RESULTS: Expression of OPN cellular/secreted protein and mRNA was greater in HepG2 than Hep3B cells (P < .01). Transient transfection of the OPN promoter construct demonstrated equivalent luciferase activities in the 2 cell lines; the rate of transcription was also equivalent as determined by chromatin immuno-precipitation assay. OPN mRNA half-life was 21 +/- 1 h and 3 +/- 1 h in HepG2 and Hep3B, respectively (P < .02). In HepG2 and Hep3B, the nucleotide sequence of OPN and its 5'-UTR, 3'-UTR, and poly (A) tail lengths were identical. A luciferase construct coupled in line with OPN-5'-UTR and OPN 3'-UTR presented greater expression in HepG2 (P < .01 vs Hep3B). Deletion of nt 10-57 of the OPN 5'-UTR restored luciferase and HA-tagged OPN protein expression in Hep3B but not in Hep G2. RNA gel-shift assays demonstrate different patterns of protein binding to OPN 5'-UTR between the 2 HCC cell lines. CONCLUSIONS: We conclude that RNA stability is a new, previously unrecognized mechanism that regulates OPN expression in HCC to convey metastatic function.

Full Text

Duke Authors

Cited Authors

  • Emani, S; Zhang, J; Guo, L; Guo, H; Kuo, PC

Published Date

  • June 2008

Published In

Volume / Issue

  • 143 / 6

Start / End Page

  • 803 - 812

PubMed ID

  • 18549897

Pubmed Central ID

  • PMC2494577

Electronic International Standard Serial Number (EISSN)

  • 1532-7361

Digital Object Identifier (DOI)

  • 10.1016/j.surg.2008.02.005


  • eng

Conference Location

  • United States