Glioblastoma cellular architectures are predicted through the characterization of two-cell interactions

Abstract

To understand how pairwise cellular interactions influence cellular architectures, we measured the levels of functional proteins associated with EGF receptor (EGFR) signaling in pairs of U87EGFR variant III oncogene receptor cells (U87EGFRvIII) at varying cell separations. Using a thermodynamics-derived approach we analyzed the cell-separation dependence of the signaling stability, and identified that the stable steady state of EGFR signaling exists when two U87EGFRvIII cells are separated by 80-100 μm. This distance range was verified as the characteristic intercellular separation within bulk cell cultures. EGFR protein network signaling coordination for the U87EGFRvIII system was lowest at the stable state and most similar to isolated cell signaling. Measurements of cultures of less tumorigenic U87PTEN cells were then used to correctly predict that stable EGFR signaling occurs for those cells at smaller cell-cell separations. The intimate relationship between functional protein levels and cellular architectures explains the scattered nature of U87EGFRvIII cells relative to U87PTEN cells in glioblastoma multiforme tumors.GBM | surprisal analysis | cancer cell-cell signaling | biological steady state | two-body cell-cell interaction P athological analysis of tumor tissues is typically led by the analyses of cellular architectures within those tumors. Relationships between those architectures and molecular biomarkers of disease are often poorly understood. We seek to establish such a relationship, starting from physical principles. We take as an example glioblastoma multiforme (GBM) cancer cells that express the EGF receptor (EGFR) variant III oncogene receptor (EGFRvIII). Although these cells enhance tumorigenicity, invasion, and other hallmarks of cancer (1, 2), they comprise only a subpopulation of the cancer cells within an EGFRvIII+ tumor, and their distribution is diffuse (1, 3, 4). To help understand this diffuse cellular architecture, we developed an experimentaltheoretical methodology based on analysis of EGFR signaling in two interacting cells. In many physical systems-from planets to atomic solids-the interactions of an element of that system with its surroundings can be understood within the context of two-body interactions. This broad observation inspired our experimental approach, which was to measure EGFR-associated signaling activity in statistically significant numbers of two EGFRvIII+ GBM cells, as a function of intercellular separation. Our theoretical approach was similarly inspired: it assumed that the resultant two-cell data sets could be interpreted using thermodynamic-like considerations.Our approach allows a determination of the stability of a phosphoprotein signaling network in two interacting cells, and demonstrates how that stability dictates the cell-cell distance distribution in a bulk culture. Using this concept we determined the most probable intercellular separation distance range within cell populations, and the deviations thereof. The available literature suggests our conclusion...

Fundamental Limits to Collective Concentration Sensing in Cell Populations

“…3. The authors argued that this spacing minimized the signaling noise [43], suggesting a mechanism similar to the one we uncover here.…”

“…We predict that the concentration detection threshold for communicating cells should decrease with the cell number, which could be tested using an intracellular fluorescent reporter. Moreover, if cell positions are controllable [43], we predict that a small concentration would be detected by modestly separated cells, but not adjacent or far-apart cells. It will be interesting to test these predictions, as well as to push the theory of collective sensing to further biological contexts.…”

“…However, other multicellular components adopt sparse cell arrangements and exhibit autocrine signaling. Recent experiments have shown that glioblastoma tumor cells in groups of N ∼ 10 3 −10 4 secrete the autocrine factors IL-6 and VEGF [43], for which D ρ ∼ 30 µm 2 /s [44] and 100 µm 2 /s [45], and ν ∼ 0.2 hr −1 [46] and 0.7 hr −1 [47], respectively, yielding λ ∼ 700 µm. Indeed, in this regime, we would predict that sparse packing provides the higher sensory precision (Fig.…”

Intercellular signaling through secreted proteins induces free-energy gradient-directed cell movement

“…Our information-theoretic analysis (10) of the experimental data regards the signaling proteins as species mediating the exchange of information between cells. This analysis is used to determine the changes with distance of the free energy of the cell-cell signaling and to show that the cell-cell relative motion can be described as a constrained Brownian motion.…”

Prédiction de la réponse moléculaire à des perturbations mesurée sur des cellules uniques

“…Récemment, il est devenu possible de mesurer la réponse du protéome de cellules uniques à des perturbations comme l'application d'anticorps [9] ou des conditions variables de pression en oxygène [10]. La variation de l'expression du protéome de deux cellules en fonction de la distance entre ces dernières a également été mesurée quantitativement [11,12]. Ces mesures sont réalisées à l'aide d'une plateforme microfluidique intégrée, appelée single cell barcode chip (SCBC) [13][14][15], qui permet de évalue les fluctuations des concentrations autour de leur valeur moyenne, N j , à l'équilibre.…”