title: Targeting HER-2/neu-overexpressing breast cancer cells by an antisense iron responsive element-directed gene expression.
abstract: Overexpression of HER-2/neu proto-oncogene is found in many human cancers including 20-30% of breast cancer and is a predictor of poor prognosis. To target breast cancer cells that overexpress HER-2/neu mRNA, we previously described a novel strategy that combines the principle of antisense (AS) and translational inhibitory activity conferred by an iron-responsive element (IRE) (AS-IRE). Here, we showed that three potential AS-IREs, i.e. AS-IRE1, 4, and 5, derived from HER-2/neu antisense sequence could bind endogenous iron regulatory protein (IRP) and, when placed in 5' untranslated region (5'UTR) of a reporter gene, the gene expression could be translationally repressed by recombinant IRP in vitro. Using AS-IRE4 as our model, we demonstrated that it is regulated by iron, and importantly, such regulation is impaired in HER-2/neu-overexpressing breast cancer cells. Furthermore, we showed that AS-IRE4 could preferentially direct the expression of a reporter gene in HER-2/neu-overexpressing breast cancer cells. Interestingly, when AS-IRE4 was placed in 5'UTR of Bax gene, a pro-apoptotic protein in the Bcl-2 protein family, we observed a preferential cell killing in breast cancer cells that overexpress HER-2/neu. Taken together, our results suggest that AS-IRE behaves as a functional IRE and it may direct therapeutic gene expression to preferentially target HER-2/neu-overexpressing breast cancer cells.
authors.affiliation: Department of Molecular and Cellular Oncology, The University of Texas, M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: W
authors.initials: W
authors.lastname: Xia
authors.forename: B
authors.initials: B
authors.lastname: Fang
authors.forename: D H
authors.initials: DH
authors.lastname: Yan
mesh_terms: D016375:Antisense Elements (Genetics) / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism; D016384:Consensus Sequence; D017931:DNA Primers / Q000737:chemistry; D005260:Female; D015870:Gene Expression; D018390:Gene Targeting; D006801:Humans; D066298:In Vitro Techniques; D007501:Iron / Q000378:metabolism; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins / Q000235:genetics*; D014176:Protein Biosynthesis; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger / Q000235:genetics*; D012334:RNA, Neoplasm / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D051028:bcl-2-Associated X Protein
chemical_list: D016375:Antisense Elements (Genetics); D017931:DNA Primers; D007501:Iron; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D016601:RNA-Binding Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D011994:Recombinant Proteins; D051028:bcl-2-Associated X Protein; C494826:BAX protein, human; C000715470:MAS1 protein, human