The ErbB-2 gene is amplified and the resulting protein product overexpressed in 15-30% of breast tumors, and associated with aggressive behavior and poor overall survival. Currently, there are two FDA approved therapies targeting ErbB-2 for the treatment of ErbB-2 positive breast cancer: trastuzumab, a humanized monoclonal antibody is directed against the extracellular domain of ErbB-2 and lapatinib, a dual EGFR/ErbB-2 tyrosine kinase inhibitor. Unfortunately, anti-ErbB-2 therapy resistance remains a major problem in metastatic breast cancer. Our data suggested that gene amplification or overexpression of ErbB-2 inhibits Notch-1 transcriptional activity and trastuzumab or lapatinib increased
Notch-1 transcriptional activity. Furthermore, Notch-1 is a breast oncogene and a novel target for the treatment of trastuzumab resistant ErbB-2 positive breast cancer in vitro. The Notch-1 receptor is overexpressed with its ligand Jagged-1 in breast cancers with the poorest overall survival. We showed that ErbB-2 inhibition activates Notch-1 which
results in a compensatory increase in Notch-1-mediated proliferation. However, we do not yet know the mechanism by which ErbB-2 overexpression suppresses Notch-1 activity and whether inhibition of Notch-1 would reverse resistance to trastuzumab in vivo. Our results demonstrated that trastuzumab or lapatinib treatment of SKBr3 cells
increased the cell surface protein expression of Jagged-1 by flow cytometry and cell surface biotinylation. Moreover, confocal studies indicated that Jagged-1 and Notch-1 co-localized possibly in early endosomal antigen-1 (EEA-1) positive vesicles. However, upon treatment with trastuzumab, Jagged-1 and Notch-1 don't co-localize. Jagged-1 is
present at the plasma membrane and Notch-1 is distributed throughout the cell. In SKBr3 and MCF-7/HER-2 breast cancer cells, ErbB-2 stabilizes the protein levels of Jagged-1. We demonstrated for the first time that Jagged-1 inhibits Notch in cis. More interestingly, ErbB-2 prevents Jagged-1-mediated trans-activation of Notch signaling by
limiting the association of Jagged-1 and Mib-1 and subsequent ubiquitylation of Jagged-1. Moreover, Mib-1 is the E3 ubiquitin ligase required for lapatinib-mediated ubiquitylation of Jagged-1 and induction of Notch activity. Additionally, ErbB-2 promotes an association between Jagged-1 and PKCá. Further, PKCá inhibits Notch transcriptional activity. Importantly combined inhibition of Jagged-1 by siRNA and ErbB-2 by trastuzumab significantly growth arrested SKBr3, BT474 HS, and BT474 HR cells in G1 phase of the cell cycle and induced cell death in vitro. Combined inhibition of Notch and ErbB-2 signaling pathways could decrease recurrence rates for ErbB-2 positive breast tumors and may be beneficial in the treatment of recurrent trastuzumab resistant disease. Our studies will elucidate the mechanism by which ErbB-2 and Notch pathways crosstalk in ErbB-2 positive breast cancer cells. Mechanisms underlying transactivation and cis-inhibition of Notch by its ligand even though not well characterized yet are critical processes regulating Notch activity. These findings will provide a mechanism and functional relevance of Jagged-1-Notch interactions in ErbB-2 positive breast cancer cells. Furthermore, these studies will identify Jagged-1 as a novel and better therapeutic target for the treatment of ErbB-2 positive breast cancer. Finally, these studies will provide a preclinical proof of concept for future clinical trials using combination of trastuzumab or lapatinib and a Notch pathway inhibitor (GSI or Jagged-1 targeted therapy) for the treatment of ErbB-2 positive breast cancer.
","abstract_html":"<p>The ErbB-2 gene is amplified and the resulting protein product overexpressed in 15-30% of breast tumors, and associated with aggressive behavior and poor overall survival. Currently, there are two FDA approved therapies targeting ErbB-2 for the treatment of ErbB-2 positive breast cancer: trastuzumab, a humanized monoclonal antibody is directed against the extracellular domain of ErbB-2 and lapatinib, a dual EGFR/ErbB-2 tyrosine kinase inhibitor. Unfortunately, anti-ErbB-2 therapy resistance remains a major problem in metastatic breast cancer. Our data suggested that gene amplification or overexpression of ErbB-2 inhibits Notch-1 transcriptional activity and trastuzumab or lapatinib increased</p><p>Notch-1 transcriptional activity. Furthermore, Notch-1 is a breast oncogene and a novel target for the treatment of trastuzumab resistant ErbB-2 positive breast cancer in vitro. The Notch-1 receptor is overexpressed with its ligand Jagged-1 in breast cancers with the poorest overall survival. We showed that ErbB-2 inhibition activates Notch-1 which</p><p>results in a compensatory increase in Notch-1-mediated proliferation. However, we do not yet know the mechanism by which ErbB-2 overexpression suppresses Notch-1 activity and whether inhibition of Notch-1 would reverse resistance to trastuzumab in vivo. Our results demonstrated that trastuzumab or lapatinib treatment of SKBr3 cells</p><p>increased the cell surface protein expression of Jagged-1 by flow cytometry and cell surface biotinylation. Moreover, confocal studies indicated that Jagged-1 and Notch-1 co-localized possibly in early endosomal antigen-1 (EEA-1) positive vesicles. However, upon treatment with trastuzumab, Jagged-1 and Notch-1 don't co-localize. Jagged-1 is</p><p>present at the plasma membrane and Notch-1 is distributed throughout the cell. In SKBr3 and MCF-7/HER-2 breast cancer cells, ErbB-2 stabilizes the protein levels of Jagged-1. We demonstrated for the first time that Jagged-1 inhibits Notch in cis. More interestingly, ErbB-2 prevents Jagged-1-mediated trans-activation of Notch signaling by</p><p>limiting the association of Jagged-1 and Mib-1 and subsequent ubiquitylation of Jagged-1. Moreover, Mib-1 is the E3 ubiquitin ligase required for lapatinib-mediated ubiquitylation of Jagged-1 and induction of Notch activity. Additionally, ErbB-2 promotes an association between Jagged-1 and PKCá. Further, PKCá inhibits Notch transcriptional activity. Importantly combined inhibition of Jagged-1 by siRNA and ErbB-2 by trastuzumab significantly growth arrested SKBr3, BT474 HS, and BT474 HR cells in G1 phase of the cell cycle and induced cell death in vitro. Combined inhibition of Notch and ErbB-2 signaling pathways could decrease recurrence rates for ErbB-2 positive breast tumors and may be beneficial in the treatment of recurrent trastuzumab resistant disease. Our studies will elucidate the mechanism by which ErbB-2 and Notch pathways crosstalk in ErbB-2 positive breast cancer cells. Mechanisms underlying transactivation and cis-inhibition of Notch by its ligand even though not well characterized yet are critical processes regulating Notch activity. These findings will provide a mechanism and functional relevance of Jagged-1-Notch interactions in ErbB-2 positive breast cancer cells. Furthermore, these studies will identify Jagged-1 as a novel and better therapeutic target for the treatment of ErbB-2 positive breast cancer. Finally, these studies will provide a preclinical proof of concept for future clinical trials using combination of trastuzumab or lapatinib and a Notch pathway inhibitor (GSI or Jagged-1 targeted therapy) for the treatment of ErbB-2 positive breast cancer.</p>","abstract_has_math":false,"creators":["Pandya, Kinnari"],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Molecular Biology","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2013,"date_issued":"2013-01-01T08:00:00Z","date_published":"2013-01-01T08:00:00Z","updated_at":"2026-07-24T02:55:44Z","subjects":["Breast Cancer","ErbB-2","Jagged-1","Mindbomb1","Notch","PKCalpha","Molecular Biology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://ecommons.luc.edu/luc_diss/680","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Pandya, Kinnari"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2016-03-31T17:14:17Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Molecular Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Breast Cancer","ErbB-2","Jagged-1","Mindbomb1","Notch","PKCalpha","Molecular Biology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://ecommons.luc.edu/luc_diss/680"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The ErbB-2 gene is amplified and the resulting protein product overexpressed in 15-30% of breast tumors, and associated with aggressive behavior and poor overall survival. Currently, there are two FDA approved therapies targeting ErbB-2 for the treatment of ErbB-2 positive breast cancer: trastuzumab, a humanized monoclonal antibody is directed against the extracellular domain of ErbB-2 and lapatinib, a dual EGFR/ErbB-2 tyrosine kinase inhibitor. Unfortunately, anti-ErbB-2 therapy resistance remains a major problem in metastatic breast cancer. Our data suggested that gene amplification or overexpression of ErbB-2 inhibits Notch-1 transcriptional activity and trastuzumab or lapatinib increased
Notch-1 transcriptional activity. Furthermore, Notch-1 is a breast oncogene and a novel target for the treatment of trastuzumab resistant ErbB-2 positive breast cancer in vitro. The Notch-1 receptor is overexpressed with its ligand Jagged-1 in breast cancers with the poorest overall survival. We showed that ErbB-2 inhibition activates Notch-1 which
results in a compensatory increase in Notch-1-mediated proliferation. However, we do not yet know the mechanism by which ErbB-2 overexpression suppresses Notch-1 activity and whether inhibition of Notch-1 would reverse resistance to trastuzumab in vivo. Our results demonstrated that trastuzumab or lapatinib treatment of SKBr3 cells
increased the cell surface protein expression of Jagged-1 by flow cytometry and cell surface biotinylation. Moreover, confocal studies indicated that Jagged-1 and Notch-1 co-localized possibly in early endosomal antigen-1 (EEA-1) positive vesicles. However, upon treatment with trastuzumab, Jagged-1 and Notch-1 don't co-localize. Jagged-1 is
present at the plasma membrane and Notch-1 is distributed throughout the cell. In SKBr3 and MCF-7/HER-2 breast cancer cells, ErbB-2 stabilizes the protein levels of Jagged-1. We demonstrated for the first time that Jagged-1 inhibits Notch in cis. More interestingly, ErbB-2 prevents Jagged-1-mediated trans-activation of Notch signaling by
limiting the association of Jagged-1 and Mib-1 and subsequent ubiquitylation of Jagged-1. Moreover, Mib-1 is the E3 ubiquitin ligase required for lapatinib-mediated ubiquitylation of Jagged-1 and induction of Notch activity. Additionally, ErbB-2 promotes an association between Jagged-1 and PKCá. Further, PKCá inhibits Notch transcriptional activity. Importantly combined inhibition of Jagged-1 by siRNA and ErbB-2 by trastuzumab significantly growth arrested SKBr3, BT474 HS, and BT474 HR cells in G1 phase of the cell cycle and induced cell death in vitro. Combined inhibition of Notch and ErbB-2 signaling pathways could decrease recurrence rates for ErbB-2 positive breast tumors and may be beneficial in the treatment of recurrent trastuzumab resistant disease. Our studies will elucidate the mechanism by which ErbB-2 and Notch pathways crosstalk in ErbB-2 positive breast cancer cells. Mechanisms underlying transactivation and cis-inhibition of Notch by its ligand even though not well characterized yet are critical processes regulating Notch activity. These findings will provide a mechanism and functional relevance of Jagged-1-Notch interactions in ErbB-2 positive breast cancer cells. Furthermore, these studies will identify Jagged-1 as a novel and better therapeutic target for the treatment of ErbB-2 positive breast cancer. Finally, these studies will provide a preclinical proof of concept for future clinical trials using combination of trastuzumab or lapatinib and a Notch pathway inhibitor (GSI or Jagged-1 targeted therapy) for the treatment of ErbB-2 positive breast cancer.
"]},{"key":"dc:title","label":"Title","values":["Novel Role of ErbB-2 in Inhibition of Jagged-1-Mediated Trans-Activation of Notch in Breast Cancer"]}]}],"canonical_facts":{"dc:creator":["Pandya, Kinnari"],"dc:date.available":["2016-03-31T17:14:17Z"],"dc:description.abstract":["The ErbB-2 gene is amplified and the resulting protein product overexpressed in 15-30% of breast tumors, and associated with aggressive behavior and poor overall survival. Currently, there are two FDA approved therapies targeting ErbB-2 for the treatment of ErbB-2 positive breast cancer: trastuzumab, a humanized monoclonal antibody is directed against the extracellular domain of ErbB-2 and lapatinib, a dual EGFR/ErbB-2 tyrosine kinase inhibitor. Unfortunately, anti-ErbB-2 therapy resistance remains a major problem in metastatic breast cancer. Our data suggested that gene amplification or overexpression of ErbB-2 inhibits Notch-1 transcriptional activity and trastuzumab or lapatinib increased
Notch-1 transcriptional activity. Furthermore, Notch-1 is a breast oncogene and a novel target for the treatment of trastuzumab resistant ErbB-2 positive breast cancer in vitro. The Notch-1 receptor is overexpressed with its ligand Jagged-1 in breast cancers with the poorest overall survival. We showed that ErbB-2 inhibition activates Notch-1 which
results in a compensatory increase in Notch-1-mediated proliferation. However, we do not yet know the mechanism by which ErbB-2 overexpression suppresses Notch-1 activity and whether inhibition of Notch-1 would reverse resistance to trastuzumab in vivo. Our results demonstrated that trastuzumab or lapatinib treatment of SKBr3 cells
increased the cell surface protein expression of Jagged-1 by flow cytometry and cell surface biotinylation. Moreover, confocal studies indicated that Jagged-1 and Notch-1 co-localized possibly in early endosomal antigen-1 (EEA-1) positive vesicles. However, upon treatment with trastuzumab, Jagged-1 and Notch-1 don't co-localize. Jagged-1 is
present at the plasma membrane and Notch-1 is distributed throughout the cell. In SKBr3 and MCF-7/HER-2 breast cancer cells, ErbB-2 stabilizes the protein levels of Jagged-1. We demonstrated for the first time that Jagged-1 inhibits Notch in cis. More interestingly, ErbB-2 prevents Jagged-1-mediated trans-activation of Notch signaling by
limiting the association of Jagged-1 and Mib-1 and subsequent ubiquitylation of Jagged-1. Moreover, Mib-1 is the E3 ubiquitin ligase required for lapatinib-mediated ubiquitylation of Jagged-1 and induction of Notch activity. Additionally, ErbB-2 promotes an association between Jagged-1 and PKCá. Further, PKCá inhibits Notch transcriptional activity. Importantly combined inhibition of Jagged-1 by siRNA and ErbB-2 by trastuzumab significantly growth arrested SKBr3, BT474 HS, and BT474 HR cells in G1 phase of the cell cycle and induced cell death in vitro. Combined inhibition of Notch and ErbB-2 signaling pathways could decrease recurrence rates for ErbB-2 positive breast tumors and may be beneficial in the treatment of recurrent trastuzumab resistant disease. Our studies will elucidate the mechanism by which ErbB-2 and Notch pathways crosstalk in ErbB-2 positive breast cancer cells. Mechanisms underlying transactivation and cis-inhibition of Notch by its ligand even though not well characterized yet are critical processes regulating Notch activity. These findings will provide a mechanism and functional relevance of Jagged-1-Notch interactions in ErbB-2 positive breast cancer cells. Furthermore, these studies will identify Jagged-1 as a novel and better therapeutic target for the treatment of ErbB-2 positive breast cancer. Finally, these studies will provide a preclinical proof of concept for future clinical trials using combination of trastuzumab or lapatinib and a Notch pathway inhibitor (GSI or Jagged-1 targeted therapy) for the treatment of ErbB-2 positive breast cancer.
"],"dc:identifier":["https://ecommons.luc.edu/luc_diss/680"],"dc:subject":["Breast Cancer","ErbB-2","Jagged-1","Mindbomb1","Notch","PKCalpha","Molecular Biology"],"dc:title":["Novel Role of ErbB-2 in Inhibition of Jagged-1-Mediated Trans-Activation of Notch in Breast Cancer"],"thesis:degree_discipline":["Molecular Biology"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T02:55:44Z"}