Premium
IL‐1β induces stabilization of IL‐8 mRNA in malignant breast cancer cells via the 3′ untranslated region: Involvement of divergent RNA‐binding factors HuR, KSRP and TIAR
Author(s) -
Suswam Esther A.,
Nabors L. Burt,
Huang Yuanyuan,
Yang Xiuhua,
King Peter H.
Publication year - 2004
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.20675
Subject(s) - rna binding protein , untranslated region , three prime untranslated region , immunoprecipitation , au rich element , messenger rna , rna , cytokine , microbiology and biotechnology , biology , cancer research , cell culture , gene , immunology , biochemistry , genetics
IL‐8 plays an integral role in promoting the malignant phenotype in breast cancer, and its production is directly influenced by inflammatory cytokines in the tumor microenvironment. Here, we show that activation of IL‐1β receptors on malignant HS578t and MDA‐MB‐231 breast cancer cells strongly induces IL‐8 expression and that RNA stabilization is persistently activated at least 12–24 hr after stimulation. SB 203580 and rapamycin reversed the RNA stabilization effect of IL‐1β in a dose‐dependent manner, suggesting involvement of the p38/MAP kinase and mTOR pathways. A luciferase reporter assay indicated that the stabilization effect was dependent on cis elements in the 3′‐untranslated region (UTR) of the IL‐8 transcript. By UV cross‐linking, we identified multiple cellular factors that interact with the IL‐8 3′UTR, ranging 34–76 kDa. Immunoprecipitation analysis indicated that HuR, KSRP and TIAR bound to one or more loci in the 3′UTR. While the cross‐linking patterns were similar, quantitative immunoprecipitation of native IL‐8 RNA from IL‐1β‐stimulated cytoplasmic extract revealed a 20‐fold greater association of transcript with the stabilizing factor HuR vs. the destabilizing factor KSRP. In conclusion, IL‐1β is a potent cytokine stimulus for IL‐8 RNA stabilization in breast cancer cells, possibly by enhanced binding of cytoplasmic HuR to the 3′UTR. Published 2004 Wiley‐Liss, Inc.