Cancer cells suppress NK cell activity by actin-driven polarization of inhibitory ligands to the immunological synapse.

Natural killer (NK) cells engage target cells via the immunological synapse (IS), where inhibitory and activating signals determine whether NK cell cytotoxicity is suppressed or activated. We previously reported that cancer cells can rapidly remodel their actin cytoskeleton upon NK cell engagement, leading to F-actin accumulation at the synapse. Here, we show that this process inhibits NK cell activation as indicated by impaired MTOC and lytic granule polarization.

A comprehensive guide to study the immunological synapse using imaging flow cytometry.

Cytotoxic lymphocytes, such as cytotoxic T cells and natural killer (NK) cells, are instrumental in the recognition and eradication of pathogenic cells, notably those undergoing malignant transformation. Cytotoxic lymphocytes establish direct contact with cancer cells via the formation of a specialized cell-cell junction known as the lytic immunological synapse. This structure serves as a critical platform for lymphocytes to integrate surface signals from potential cancer cells and to direct their cytolytic apparatus toward the confirmed targets.

Actin cytoskeleton remodeling at the cancer cell side of the immunological synapse: good, bad, or both?

Cytotoxic lymphocytes (CLs), specifically cytotoxic T lymphocytes and natural killer cells, are indispensable guardians of the immune system and orchestrate the recognition and elimination of cancer cells. Upon encountering a cancer cell, CLs establish a specialized cellular junction, known as the immunological synapse that stands as a pivotal determinant for effective cell killing. Extensive research has focused on the presynaptic side of the immunological synapse and elucidated the multiple functions of the CL actin cytoskeleton in synapse formation, organization, regulatory signaling, and lytic activity.

Actin cytoskeleton depolymerization increases matrix metalloproteinase gene expression in breast cancer cells by promoting translocation of cysteine-rich protein 2 to the nucleus.

The actin cytoskeleton plays a critical role in cancer cell invasion and metastasis; however, the coordination of its multiple functions remains unclear. Actin dynamics in the cytoplasm control the formation of invadopodia, which are membrane protrusions that facilitate cancer cell invasion by focusing the secretion of extracellular matrix-degrading enzymes, including matrix metalloproteinases (MMPs). In this study, we investigated the nuclear role of cysteine-rich protein 2 (CRP2), a two LIM domain-containing F-actin-binding protein that we previously identified as a cytoskeletal component of invadopodia, in breast cancer cells.

Measuring CTL Lytic Granule Secretion and Target Cell Membrane Repair by Fluorescent Lipophilic Dye Uptake at the Lytic Synapse.

CD8 cytotoxic T lymphocytes (CTL) play a key role in anti-tumor immune response. They are therefore at the heart of current immunotherapy protocols against cancer. Despite current strategies to potentiate CTL responses, cancer cells can resist CTL attack, thus limiting the efficacy of immunotherapies.

An integrated workflow for phosphopeptide identification in natural killer cells (NK-92MI) and their targets (MDA-MB-231) during immunological synapse formation.

Here, we present a protocol to identify and quantify phosphopeptides during the dynamic formation of an immunological synapse. We describe steps for mixing isotope-labeled immune and target cells, the stabilization of cell-to-cell conjugates by cross-linking, and their isolation by fluorescence-activated cell sorting. We detail the isolation of phosphopeptides by phosphopeptide enrichment and their subsequent measurement by mass spectrometry.

Ultrarapid lytic granule release from CTLs activates Ca-dependent synaptic resistance pathways in melanoma cells.

Human cytotoxic T lymphocytes (CTLs) exhibit ultrarapid lytic granule secretion, but whether melanoma cells mobilize defense mechanisms with commensurate rapidity remains unknown. We used single-cell time-lapse microscopy to offer high spatiotemporal resolution analyses of subcellular events in melanoma cells upon CTL attack. Target cell perforation initiated an intracellular Ca wave that propagated outward from the synapse within milliseconds and triggered lysosomal mobilization to the synapse, facilitating membrane repair and conferring resistance to CTL induced cytotoxicity.

How natural killer cells avoid self-destruction when killing their targets.

How cytotoxic lymphocytes are protected against their own weapons during close combat with diseased target cells is an important and long-standing question in immunology. A study in this issue provides new insights into the mechanisms by which natural killer (NK) cells avoid self-destruction.

Intrinsic Resistance of Chronic Lymphocytic Leukemia Cells to NK Cell-Mediated Lysis Can Be Overcome by Pharmacological Inhibition of Cdc42-Induced Actin Cytoskeleton Remodeling.

Natural killer (NK) cells are innate effector lymphocytes with strong antitumor effects against hematologic malignancies such as chronic lymphocytic leukemia (CLL). However, NK cells fail to control CLL progression on the long term. For effective lysis of their targets, NK cells use a specific cell-cell interface, known as the immunological synapse (IS), whose assembly and effector function critically rely on dynamic cytoskeletal changes in NK cells.