title: HER2 signaling pathway activation and response of breast cancer cells to HER2-targeting agents is dependent strongly on the 3D microenvironment.
abstract: Development of effective and durable breast cancer treatment strategies requires a mechanistic understanding of the influence of the microenvironment on response. Previous work has shown that cellular signaling pathways and cell morphology are dramatically influenced by three-dimensional (3D) cultures as opposed to traditional two-dimensional (2D) monolayers. Here, we compared 2D and 3D culture models to determine the impact of 3D architecture and extracellular matrix (ECM) on HER2 signaling and on the response of HER2-amplified breast cancer cell lines to the HER2-targeting agents Trastuzumab, Pertuzumab and Lapatinib. We show that the response of the HER2-amplified AU565, SKBR3 and HCC1569 cells to these anti-HER2 agents was highly dependent on whether the cells were cultured in 2D monolayer or 3D laminin-rich ECM gels. Inhibition of beta1 integrin, a major cell-ECM receptor subunit, significantly increased the sensitivity of the HER2-amplified breast cancer cell lines to the humanized monoclonal antibodies Trastuzumab and Pertuzumab when grown in a 3D environment. Finally, in the absence of inhibitors, 3D cultures had substantial impact on HER2 downstream signaling and induced a switch between PI3K-AKT- and RAS-MAPK-pathway activation in all cell lines studied, including cells lacking HER2 amplification and overexpression. Our data provide direct evidence that breast cancer cells are able to rapidly adapt to different environments and signaling cues by activating alternative pathways that regulate proliferation and cell survival, events that may play a significant role in the acquisition of resistance to targeted therapies.
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, University of California Berkeley, Mailstop 977R225A, 1 Cyclotron Road, Berkeley, CA 94720, USA. Britta.Weigelt@cancer.org.uk
authors.forename: Britta
authors.initials: B
authors.lastname: Weigelt
authors.forename: Alvin T
authors.initials: AT
authors.lastname: Lo
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Park
authors.forename: Joe W
authors.initials: JW
authors.lastname: Gray
authors.forename: Mina J
authors.initials: MJ
authors.lastname: Bissell
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology*; D018929:Cell Culture Techniques / Q000295:instrumentation; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D016503:Drug Delivery Systems; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation / Q000187:drug effects; D005109:Extracellular Matrix / Q000502:physiology; D005260:Female; D005782:Gels; D006801:Humans; D019012:Integrin beta1 / Q000502:physiology; D007797:Laminin / Q000494:pharmacology; D000077341:Lapatinib; D009363:Neoplasm Proteins / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D005782:Gels; D019012:Integrin beta1; D007797:Laminin; D000077341:Lapatinib; D009363:Neoplasm Proteins; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C508053:ERBB2 protein, human; C485206:pertuzumab
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