title: HER Specific TKIs Exert Their Antineoplastic Effects on Breast Cancer Cell Lines through the Involvement of STAT5 and JNK.
abstract: BACKGROUND
  HER-targeted tyrosine kinase inhibitors (TKIs) have demonstrated pro-apoptotic and antiproliferative effects in vitro and in vivo. The exact pathways through which TKIs exert their antineoplastic effects are, however, still not completely understood.
  
  
  METHODS
  Using Milliplex assays, we have investigated the effects of the three panHER-TKIs lapatinib, canertinib and afatinib on signal transduction cascade activation in SKBR3, T47D and Jurkat neoplastic cell lines. The growth-inhibitory effect of blockade of HER and of JNK and STAT5 signaling was measured by proliferation- and apoptosis-assays using formazan dye labeling of viable cells, Western blotting for cleaved PARP-1 and immunolabeling for active caspase 3, respectively.
  
  
  RESULTS
  All three HER-TKIs clearly inhibited proliferation and increased apoptosis in HER2 overexpressing SKBR3 cells, while their effect was less pronounced on HER2 moderately expressing T47D cells where they exerted only a weak antiproliferative and essentially no pro-apoptotic effect. Remarkably, phosphorylation/activation of JNK and STAT5A/B were inhibited by HER-TKIs only in the sensitive, but not in the resistant cells. In contrast, phosphorylation/activation of ERK/MAPK, STAT3, CREB, p70 S6 kinase, IkBa, and p38 were equally affected by HER-TKIs in both cell lines. Moreover, we demonstrated that direct pharmacological blockade of JNK and STAT5 abrogates cell growth in both HER-TKI-sensitive as well as -resistant breast cancer cells, respectively.
  
  
  CONCLUSIONS
  We have shown that HER-TKIs exert a HER2 expression-dependent anti-cancer effect in breast cancer cell lines. This involves blockade of JNK and STAT5A/B signaling, which have been found to be required for in vitro growth of these cell lines.
authors.affiliation: Division of Gynecology, Department of OB/GYN and Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria.
authors.forename: Daphne
authors.initials: D
authors.lastname: Gschwantler-Kaulich
authors.affiliation: Signaling Networks Program, Division of Oncology, Department of Medicine I and Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria.|Ludwig Boltzmann Cluster Oncology, Vienna, Austria.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Grunt
authors.affiliation: Division of Gynecology, Department of OB/GYN and Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria.
authors.forename: Daniela
authors.initials: D
authors.lastname: Muhr
authors.affiliation: Signaling Networks Program, Division of Oncology, Department of Medicine I and Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria.
authors.forename: Renate
authors.initials: R
authors.lastname: Wagner
authors.affiliation: Division of Gynecology, Department of OB/GYN and Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria.
authors.forename: Heinz
authors.initials: H
authors.lastname: Kölbl
authors.affiliation: Division of Gynecology, Department of OB/GYN and Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria.
authors.forename: Christian F
authors.initials: CF
authors.lastname: Singer
mesh_terms: D000077716:Afatinib; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D005260:Female; D006801:Humans; D020128:Inhibitory Concentration 50; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D000077341:Lapatinib; D020935:MAP Kinase Signaling System; D009025:Morpholines / Q000494:pharmacology; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational; D011799:Quinazolines / Q000494:pharmacology; D050799:STAT5 Transcription Factor / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D009025:Morpholines; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D050799:STAT5 Transcription Factor; D000077341:Lapatinib; D000077716:Afatinib; C420268:Canertinib; D066246:ErbB Receptors; D048031:JNK Mitogen-Activated Protein Kinases