TY  - JOUR
A1  - Eitler, Jiri
A1  - Wotschel, Natalie
A1  - Miller, Nicole
A1  - Boissel, Laurent
A1  - Klingemann, Hans-Georg
A1  - Wels, Winfried
A1  - Tonn, Torsten
T1  - Inability of granule polarization by NK cells defines tumor resistance and can be overcome by CAR or ADCC mediated targeting
T2  - Journal for ImmunoTherapy of Cancer
N2  - Background: On encountering a susceptible target, natural killer (NK) cells mediate cytotoxicity through highly regulated steps of directed degranulation. Cytotoxic granules converge at the microtubule organizing center and are polarized toward the immunological synapse (IS), followed by granule exocytosis. NK cell retargeting by chimeric antigen receptors (CARs) or mAbs represents a promising strategy for overcoming tumor cell resistance. However, little is known about the lytic granule dynamics of such retargeted NK cells toward NK-cell-resistant tumors.
Methods: Here, we used spinning disk confocal microscopy for live-cell imaging to analyze granule-mediated NK cell cytotoxicity in ErbB2-targeted CAR-expressing NK-92 cells (NK-92/5.28.z) and high-affinity FcR transgenic NK-92 cells plus Herceptin toward ErbB2-positive breast cancer cells (MDA-MB-453), which are resistant to parental NK-92.
Results: Unmodified NK-92 cells cocultured with resistant cancer cells showed stable conjugate formation and granule clustering, but failed to polarize granules to the IS. In contrast, retargeting by CAR or FcR+Herceptin toward the MDA-MB-453 cells enabled granule polarization to the IS, resulting in highly effective cytotoxicity. We found that in NK-92 the phosphoinositide 3-kinase pathway was activated after contact with resistant MDA-MB-453, while phospholipase C-γ (PLCγ) and mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) were not activated. In contrast, retargeting by CAR or antibody-dependent cell-mediated cytotoxicity (ADCC) provided the missing PLCγ and MEK/ERK signals.
Conclusions: These observations suggest that NK cells can create conjugates with resistant cancer cells and respond by granule clustering, but the activation signals are insufficient to induce granule polarization and consequent release of lytic enzymes. Retargeting by CAR and/or the FcR/mAb (ADCC) axis provide the necessary signals, leading to granule polarization and thereby overcoming tumor cell resistance.
KW  - NK cells
KW  - NK-92
KW  - haNK
KW  - ADCC
KW  - Chimeric Antigen Receptor (CAR)
KW  - breast cancer
KW  - cancer immunotherapy
KW  - live-cell imaging
KW  - granule polarization
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/62987
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-629870
SN  - 2051-1426
VL  - 9
IS  - 1, art. e001334
SP  - 1
EP  - 15
PB  - BioMed Central
CY  - London
ER  -