title: Use of RNA interference to validate Brk as a novel therapeutic target in breast cancer: Brk promotes breast carcinoma cell proliferation.
abstract: Brk (PTK6) is a nonreceptor protein tyrosine kinase, which is expressed in over 60% of breast carcinoma tissue samples and breast tumour cell lines, but not normal mammary tissue or benign lesions. Since experimental Brk expression in nontransformed mammary epithelial cells enhances their mitogenic response to epidermal growth factor, it was important to determine the role Brk plays in the proliferation of breast carcinoma cells and validate it as a therapeutic target. We have used RNA interference to efficiently and specifically downregulate Brk protein levels in breast carcinoma cells, and determined that this results in a significant suppression of their proliferation. Additionally, through the expression of a kinase-inactive mutant, we have determined that Brk can mediate promotion of proliferation via a kinase-independent mechanism, potentially functioning as an 'adapter'. These data identify Brk as a novel target for antiproliferative therapy in the majority of breast cancers, and illustrate the power of RNA interference for rapidly validating candidate therapeutic targets.
authors.affiliation: School of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 OEX, UK.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Harvey
authors.forename: Mark R
authors.initials: MR
authors.lastname: Crompton
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002277:Carcinoma / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology*; D005260:Female; D006801:Humans; D009363:Neoplasm Proteins; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D034622:RNA Interference / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D009363:Neoplasm Proteins; D011505:Protein-Tyrosine Kinases; C088375:PTK6 protein, human