Cell migration through three-dimensional confining pores: speed accelerations by deformation and recoil of the nucleus.

Directional cell migration in dense three-dimensional (3D) environments critically depends upon shape adaptation and is impeded depending on the size and rigidity of the nucleus. Accordingly, the nucleus is primarily understood as a physical obstacle; however, its pro-migratory functions by stepwise deformation and reshaping remain unclear. Using atomic force spectroscopy, time-lapse fluorescence microscopy and shape change analysis tools, we determined the nuclear size, deformability, morphology and shape change of HT1080 fibrosarcoma cells expressing the Fucci cell cycle indicator or being pre-treated with chromatin-decondensating agent TSA.

Cancer cell migration in 3D tissue: negotiating space by proteolysis and nuclear deformability.

Efficient tumor cell invasion into the surrounding desmoplastic stroma is a hallmark of cancer progression and involves the navigation through available small tissue spaces existent within the dense stromal network. Such navigation includes the reciprocal adaptation of the moving tumor cell, including the nucleus as largest and stiffest organelle, to pre-existent or de-novo generated extracellular matrix (ECM) gaps, pores and trails within stromal compartments. Within the context of migration, we briefly summarize physiological and tumor-related changes in ECM geometries as well as tissue proteolysis.

Cell jamming: collective invasion of mesenchymal tumor cells imposed by tissue confinement.

Background: Cancer invasion is a multi-step process which coordinates interactions between tumor cells with mechanotransduction towards the surrounding matrix, resulting in distinct cancer invasion strategies. Defined by context, mesenchymal tumors, including melanoma and fibrosarcoma, develop either single-cell or collective invasion modes, however, the mechanical and molecular programs underlying such plasticity of mesenchymal invasion programs remain unclear.

Methods: To test how tissue anatomy determines invasion mode, spheroids of MV3 melanoma and HT1080 fibrosarcoma cells were embedded into 3D collagen matrices of varying density and stiffness and analyzed for migration type and efficacy with matrix metalloproteinase (MMP)-dependent collagen degradation enabled or pharmacologically inhibited.

Probing the compressibility of tumor cell nuclei by combined atomic force-confocal microscopy.

The cell nucleus is the largest and stiffest organelle rendering it the limiting compartment during migration of invasive tumor cells through dense connective tissue. We here describe a combined atomic force microscopy (AFM)-confocal microscopy approach for measurement of bulk nuclear stiffness together with simultaneous visualization of the cantilever-nucleus contact and the fate of the cell. Using cantilevers functionalized with either tips or beads and spring constants ranging from 0.

Physical limits of cell migration: control by ECM space and nuclear deformation and tuning by proteolysis and traction force.

Cell migration through 3D tissue depends on a physicochemical balance between cell deformability and physical tissue constraints. Migration rates are further governed by the capacity to degrade ECM by proteolytic enzymes, particularly matrix metalloproteinases (MMPs), and integrin- and actomyosin-mediated mechanocoupling. Yet, how these parameters cooperate when space is confined remains unclear.

The "DGPPN-Cohort": A national collaboration initiative by the German Association for Psychiatry and Psychotherapy (DGPPN) for establishing a large-scale cohort of psychiatric patients.

The German Association for Psychiatry and Psychotherapy (DGPPN) has committed itself to establish a prospective national cohort of patients with major psychiatric disorders, the so-called DGPPN-Cohort. This project will enable the scientific exploitation of high-quality data and biomaterial from psychiatric patients for research. It will be set up using harmonised data sets and procedures for sample generation and guided by transparent rules for data access and data sharing regarding the central research database.

Analyzing the homeostasis of signaling proteins by a combination of Western blot and fluorescence correlation spectroscopy.

The determination of intracellular protein concentrations is a prerequisite for understanding protein interaction networks in systems biology. Today, protein quantification is based either on mass spectrometry, which requires large cell numbers and sophisticated measurement protocols, or on quantitative Western blotting, which requires the expression and purification of a recombinant protein as a reference. Here, we present a method that uses a transiently expressed fluorescent fusion protein of the protein-of-interest as an easily accessible reference in small volumes of crude cell lysates.

Cytotoxic T lymphocyte migration and effector function in the tumor microenvironment.

Immunological control of cancer lesions requires local uptake of tumor-specific antigen followed by the activation and expansion of tumor specific cytotoxic T-lymphocytes (CTL). An efficient effector phase further depends upon the entry of activated CTL into the tumor microenvironment and scanning of tumor tissue, which leads to direct interaction of the CTL with target cells followed by apoptosis induction and shrinkage of the tumor lesion. Whereas the antigens and pathways that lead to efficient activation of tumor-specific CTL are well established, the local mechanisms that enable efficient - or deficient - CTL function in the tumor tissue are poorly understood.