Functional visualization of NK Cell-mediated killing of metastatic single tumor cells

ナチュラルキラー（NK）細胞による転移がん細胞殺傷の可視化 --NK細胞とがん細胞の肺毛細血管上での戦いを実況中継する--. 京都大学プレスリリース. 2022-02-07.Natural killer (NK) cells lyse invading tumor cells to limit metastatic growth in the lung, but how some cancers evade this host protective mechanism to establish a growing lesion is unknown. Here we have combined ultra-sensitive bioluminescence imaging with intravital two-photon microscopy involving genetically-encoded biosensors to examine this question. NK cells eliminated disseminated tumor cells from the lung within 24 hrs of arrival, but not thereafter. Intravital dynamic imaging revealed that 50% of NK-tumor cell encounters lead to tumor cell death in the first 4 hrs after tumor cell arrival, but after 24 hrs of arrival, nearly 100% of the interactions result in the survival of the tumor cell. During this 24 hrs period, the probability of ERK activation in NK cells upon encountering the tumor cells was decreased from 68% to 8%, which correlated with the loss of the activating ligand CD155/PVR/Necl5 from the tumor cell surface. Thus, by quantitatively visualizing the NK-tumor cell interaction at the early stage of metastasis, we have revealed the crucial parameters of NK cell immune surveillance in the lung

Multiplexed Chemical Control of Signaling Pathways by Orthogonal, Plasma Membrane-Specific SLIPT Systems

Most cell behaviors are the outcome of processing information from multiple signals generated upon cell stimulation. A systematic understanding of cellular systems requires methods that activate multiple signaling molecules or pathways in single cells. However, the construction of tools for such multiplexed signal control is challenging. Here we present orthogonal chemogenetic systems that allow control of multiple signaling pathways in living mammalian cells based on self-localizing ligand-induced protein translocation (SLIPT). Two orthogonal SLIPT systems were constructed to enable chemically inducible, individual translocation of two proteins from the cytoplasm to the inner-leaflet of the plasma membrane in the same cell. The SLIPT systems combined with fluorescent reporters achieved simultaneous multiplexed activation and monitoring of endogenous Ras/ERK and PI3K/Akt pathways in single cells. Thus, orthogonal SLIPT systems provide a powerful platform for multiplexed chemical signal control in single cells, offering new opportunities for dissecting cell signaling networks and synthetic cell manipulation.<br /

Intravital imaging identifies the VEGF-TXA₂ axis as a critical promoter of PGE₂ secretion from tumor cells and immune evasion

がん細胞が免疫から逃れるメカニズムの解明 --がん細胞と血管内皮細胞との細胞間相互作用--. 京都大学プレスリリース. 2021-05-28.Prostaglandin E₂ (PGE₂) promotes tumor progression through evasion of anti-tumor immunity. In stark contrast to cyclooxygenase-dependent production of PGE₂, little is known whether or not PGE₂ secretion is regulated within tumor tissues. Here, we show that VEGF-dependent release of thromboxane A₂ (TXA₂) triggers Ca²⁺ transients in tumor cells, culminating in PGE₂ secretion and subsequent immune evasion in the early stages of tumorigenesis. Ca²⁺ transients caused cPLA2 activation and triggered the arachidonic acid cascade. Ca²⁺ transients were monitored as the surrogate marker of PGE₂ secretion. Intravital imaging of BrafV600E mouse melanoma cells revealed that the proportion of cells exhibiting Ca²⁺ transients is markedly higher in vivo than in vitro. The TXA₂ receptor was indispensable for the Ca²⁺ transients in vivo, high intra-tumoral PGE₂ concentration, and evasion of anti-tumor immunity. Notably, treatment with a vascular endothelial growth factor (VEGF) receptor antagonist and an anti-VEGF antibody rapidly suppressed Ca²⁺ transients and reduced TXA₂ and PGE₂ concentrations in tumor tissues. These results identify the VEGF-TXA₂ axis as a critical promoter of PGE₂-dependent tumor immune evasion, providing a molecular basis underlying the immunomodulatory effect of anti-VEGF therapies

Synthetic Self-Localizing Ligands That Control the Spatial Location of Proteins in Living Cells

Small-molecule ligands that control the spatial location of proteins in living cells would be valuable tools for regulating biological systems. However, the creation of such molecules remains almost unexplored because of the lack of a design methodology. Here we introduce a conceptually new type of synthetic ligands, self-localizing ligands (SLLs), which spontaneously localize to specific subcellular regions in mammalian cells. We show that SLLs bind their target proteins and relocate (tether) them rapidly from the cytoplasm to their targeting sites, thus serving as synthetic protein translocators. SLL-induced protein translocation enables us to manipulate diverse synthetic/endogenous signaling pathways. The method is also applicable to reversible protein translocation and allows control of multiple proteins at different times and locations in the same cell. These results demonstrate the usefulness of SLLs in the spatial (and temporal) control of intracellular protein distribution and biological processes, opening a new direction in the design of small-molecule tools or drugs for cell regulation