title: Aberrant intracellular metabolism of T-DM1 confers T-DM1 resistance in human epidermal growth factor receptor 2-positive gastric cancer cells.
abstract: Trastuzumab emtansine (T-DM1), an antibody-drug conjugate (ADC) consisting of human epidermal growth factor receptor 2 (HER2)-targeted mAb trastuzumab linked to antimicrotubule agent mertansine (DM1), has been approved for the treatment of HER2-positive metastatic breast cancer. Acquired resistance has been a major obstacle to T-DM1 treatment, and mechanisms remain incompletely understood. In the present study, we established a T-DM1-resistant N87-KR cell line from HER2-positive N87 gastric cancer cells to investigate mechanisms of acquired resistance and develop strategies for overcoming it. Although the kinetics of binding, internalization, and externalization of T-DM1 were the same in N87-KR cells and N87 cells, N87-KR was strongly resistant to T-DM1, but remained sensitive to both trastuzumab and DM1. T-DM1 failed to inhibit microtubule polymerization in N87-KR cells. Consistently, lysine-MCC-DM1, the active T-DM1 metabolite that inhibits microtubule polymerization, accumulated much less in N87-KR cells than in N87 cells. Furthermore, lysosome acidification, achieved by vacuolar H+-ATPase (V-ATPase), was much diminished in N87-KR cells. Notably, treatment of sensitive N87 cells with the V-ATPase selective inhibitor bafilomycin A1 induced T-DM1 resistance, suggesting that aberrant V-ATPase activity decreases T-DM1 metabolism, leading to T-DM1 resistance in N87-KR cells. Interestingly, HER2-targeted ADCs containing a protease-cleavable linker, such as hertuzumab-vc-monomethyl auristatin E, were capable of efficiently overcoming this resistance. Our results show for the first time that a decrease in T-DM1 metabolites induced by aberrant V-ATPase activity contributes to T-DM1 resistance, which could be overcome by HER2-targeted ADCs containing different linkers, including a protease-cleavable linker. Accordingly, we propose that V-ATPase activity in lysosomes is a novel biomarker for predicting T-DM1 resistance.
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Wang
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Wenqian
authors.initials: W
authors.lastname: Wang
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Yongping
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Chen
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Haitian
authors.initials: H
authors.lastname: Quan
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Liguang
authors.identifier: http://orcid.org/0000-0001-7396-7122
authors.initials: L
authors.lastname: Lou
mesh_terms: D000080044:Ado-Trastuzumab Emtansine; D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000378:metabolism / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D006801:Humans; D018796:Immunoconjugates / Q000378:metabolism / Q000494:pharmacology; D008453:Maytansine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis; D013274:Stomach Neoplasms / Q000378:metabolism*; D000068878:Trastuzumab; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000080044:Ado-Trastuzumab Emtansine; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D018796:Immunoconjugates; D008453:Maytansine; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; D025262:Vacuolar Proton-Translocating ATPases; C508053:ERBB2 protein, human
keywords: Antibody-drug conjugate; HER2; T-DM1; V-ATPase; drug resistance