title: Reciprocal effects of STAT5 and STAT3 in breast cancer.
abstract: Breast cancer is often associated with inappropriate activation of transcription factors involved in normal mammary development. Two related transcription factors, signal transducer and activator of transcription (STAT) 5 and STAT3, play important and distinct roles in mammary development and both can be activated in breast cancer. However, the relative contribution of these STATs to mammary tumorigenesis is unknown. We have found that primary human breast tumors displaying activation of both STATs are more differentiated than those with STAT3 activation alone and display more favorable prognostic characteristics. To understand this difference, we have analyzed the effect of these STATs on gene regulation and phenotype of mammary carcinoma cells. STAT5 and STAT3 mediate opposing effects on several key target genes, with STAT5 exerting a dominant role. Using a model system of paired breast cancer cell lines, we found that coactivation of STAT5 and STAT3 leads to decreased proliferation and increased sensitivity to the chemotherapeutic drugs paclitaxel and vinorelbine compared with cells that have only STAT3 activation. Thus, STAT5 can modify the effects of STAT3 from the level of gene expression to cellular phenotype and analysis of the activation state of both STAT5 and STAT3 may provide important diagnostic and prognostic information in breast cancer.
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Walker
authors.forename: Erik A
authors.initials: EA
authors.lastname: Nelson
authors.forename: Lihua
authors.initials: L
authors.lastname: Zou
authors.forename: Mousumi
authors.initials: M
authors.lastname: Chaudhury
authors.forename: Sabina
authors.initials: S
authors.lastname: Signoretti
authors.forename: Andrea
authors.initials: A
authors.lastname: Richardson
authors.forename: David A
authors.initials: DA
authors.lastname: Frank
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation / Q000502:physiology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D020411:Oligonucleotide Array Sequence Analysis; D017239:Paclitaxel / Q000494:pharmacology; D010641:Phenotype; D051560:Proto-Oncogene Proteins c-bcl-6; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014747:Vinblastine / Q000031:analogs & derivatives / Q000494:pharmacology; D000077235:Vinorelbine
chemical_list: C084103:BCL6 protein, human; D004268:DNA-Binding Proteins; D051560:Proto-Oncogene Proteins c-bcl-6; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050799:STAT5 Transcription Factor; D014747:Vinblastine; D017239:Paclitaxel; D000077235:Vinorelbine