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  1. Article ; Online: Correction: Mcl-1 confers protection of Her2-positive breast cancer cells to hypoxia: therapeutic implications.

    Bashari, Muhammad Hasan / Fan, Fengjuan / Vallet, Sonia / Sattler, Martin / Arn, Melissa / Luckner-Minden, Claudia / Schulze-Bergkamen, Henning / Zörnig, Inka / Marme, Frederik / Schneeweiss, Andreas / Cardone, Michael H / Opferman, Joseph T / Jäger, Dirk / Podar, Klaus

    Breast cancer research : BCR

    2024  Volume 26, Issue 1, Page(s) 58

    Language English
    Publishing date 2024-04-02
    Publishing country England
    Document type Published Erratum
    ZDB-ID 2015059-3
    ISSN 1465-542X ; 1465-5411
    ISSN (online) 1465-542X
    ISSN 1465-5411
    DOI 10.1186/s13058-024-01811-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Mcl-1 confers protection of Her2-positive breast cancer cells to hypoxia: therapeutic implications.

    Bashari, Muhammad Hasan / Fan, Fengjuan / Vallet, Sonia / Sattler, Martin / Arn, Melissa / Luckner-Minden, Claudia / Schulze-Bergkamen, Henning / Zörnig, Inka / Marme, Frederik / Schneeweiss, Andreas / Cardone, Michael H / Opferman, Joseph T / Jäger, Dirk / Podar, Klaus

    Breast cancer research : BCR

    2016  Volume 18, Issue 1, Page(s) 26

    Abstract: Background: Molecular mechanisms leading to the adaptation of breast cancer (BC) cells to hypoxia are largely unknown. The anti-apoptotic Bcl-2 family member myeloid cell leukemia-1 (Mcl-1) is frequently amplified in BC; and elevated Mcl-1 levels have ... ...

    Abstract Background: Molecular mechanisms leading to the adaptation of breast cancer (BC) cells to hypoxia are largely unknown. The anti-apoptotic Bcl-2 family member myeloid cell leukemia-1 (Mcl-1) is frequently amplified in BC; and elevated Mcl-1 levels have been correlated with poor prognosis. Here we investigated the pathophysiologic role of Mcl-1 in Her2-positive BC cells under hypoxic conditions.
    Methods: RNA interference and a novel small molecule inhibitor, EU-5346, were used to examine the role of Mcl-1 in Her2-positive BC cell lines and primary BC cells (sensitive or intrinsically resistant to Her2 inhibitors) under hypoxic conditions (using a hypoxic incubation chamber). Mechanisms-of-action were investigated by RT-PCR, mitochondrial isolation, as well as immunoprecipitation/blotting analysis, and microscopy. The specificity against Mcl-1 of the novel small molecule inhibitor EU5346 was verified in Mcl-1(Δ/null) versus Mcl-1(wt/wt) Murine Embryonic Fibroblasts (MEFs). Proliferation, survival, and spheroid formation were assessed in response to Mcl-1 and Her2 inhibition.
    Results: We demonstrate for a strong correlation between high Mcl-1 protein levels and hypoxia, predominantly in Her2-positive BC cells. Surprisingly, genetic depletion of Mcl-1 decreased Her2 and Hif-1α levels followed by inhibition of BC cell survival. In contrast, Mcl-1 protein levels were not downregulated after genetic depletion of Her2 indicating a regulatory role of Mcl-1 upstream of Her2. Indeed, Mcl-1 and Her2 co-localize within the mitochondrial fraction and form a Mcl-1/Her2- protein complex. Similar to genetically targeting Mcl-1 the novel small molecule Mcl-1 inhibitor EU-5346 induced cell death and decreased spheroid formation in Her2-positive BC cells. Of interest, EU-5346 induced ubiquitination of Mcl-1- bound Her2 demonstrating a previously unknown role for Mcl-1 to stabilize Her2 protein levels. Importantly, targeting Mcl-1 was also active in Her2-positive BC cells resistant to Her2 inhibitors, including a brain-primed Her2-positive cell line.
    Conclusion: Our data demonstrate a critical role of Mcl-1 in Her2-positive BC cell survival under hypoxic conditions and provide the preclinical framework for the therapeutic use of novel Mcl-1- targeting agents to improve patient outcome in BC.
    MeSH term(s) Animals ; Apoptosis/genetics ; Breast Neoplasms/genetics ; Breast Neoplasms/pathology ; Cell Hypoxia/genetics ; Cell Line, Tumor ; Cell Proliferation/genetics ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; Mice ; Myeloid Cell Leukemia Sequence 1 Protein/biosynthesis ; Myeloid Cell Leukemia Sequence 1 Protein/genetics ; RNA Interference ; Receptor, ErbB-2/genetics ; Signal Transduction/genetics
    Chemical Substances MCL1 protein, human ; Myeloid Cell Leukemia Sequence 1 Protein ; ERBB2 protein, human (EC 2.7.10.1) ; Receptor, ErbB-2 (EC 2.7.10.1)
    Language English
    Publishing date 2016-02-26
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2015059-3
    ISSN 1465-542X ; 1465-5411
    ISSN (online) 1465-542X
    ISSN 1465-5411
    DOI 10.1186/s13058-016-0686-4
    Database MEDical Literature Analysis and Retrieval System OnLINE

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