资源环境科技发展态势分析平台

KRAS GTPases are activated in one-third of cancers, and KRAS(G12C) is one of the most common activating alterations in lung adenocarcinoma(1,2). KRAS(G12C) inhibitors(3,4) are in phase-I clinical trials and early data show partial responses in nearly half of patients with lung cancer. How cancer cells bypass inhibition to prevent maximal response to therapy is not understood. Because KRAS(G12C) cycles between an active and inactive conformation(4-6), and the inhibitors bind only to the latter, we tested whether isogenic cell populations respond in a non-uniform manner by studying the effect of treatment at a single-cell resolution. Here we report that, shortly after treatment, some cancer cells are sequestered in a quiescent state with low KRAS activity, whereas others bypass this effect to resume proliferation. This rapid divergent response occurs because some quiescent cells produce new KRAS(G12C) in response to suppressed mitogen-activated protein kinase output. New KRAS(G12C) is maintained in its active, drug-insensitive state by epidermal growth factor receptor and aurora kinase signalling. Cells without these adaptive changes-or cells in which these changes are pharmacologically inhibited-remain sensitive to drug treatment, because new KRAS(G12C) is either not available or exists in its inactive, drug-sensitive state. The direct targeting of KRAS oncoproteins has been a longstanding objective in precision oncology. Our study uncovers a flexible non-uniform fitness mechanism that enables groups of cells within a population to rapidly bypass the effect of treatment. This adaptive process must be overcome if we are to achieve complete and durable responses in the clinic.

The sensing of DNA damage by the AIM2 inflammasome promotes the death of central nervous system cells and is required for normal brain development.

Neurodevelopment is characterized by rapid rates of neural cell proliferation and differentiation followed by massive cell death in which more than half of all recently generated brain cells are pruned back. Large amounts of DNA damage, cellular debris, and by-products of cellular stress are generated during these neurodevelopmental events, all of which can potentially activate immune signalling. How the immune response to this collateral damage influences brain maturation and function remains unknown. Here we show that the AIM2 inflammasome contributes to normal brain development and that disruption of this immune sensor of genotoxic stress leads to behavioural abnormalities. During infection, activation of the AIM2 inflammasome in response to double-stranded DNA damage triggers the production of cytokines as well as a gasdermin-D-mediated form of cell death known as pyroptosis(1-4). We observe pronounced AIM2 inflammasome activation in neurodevelopment and find that defects in this sensor of DNA damage result in anxiety-related behaviours in mice. Furthermore, we show that the AIM2 inflammasome contributes to central nervous system (CNS) homeostasis specifically through its regulation of gasdermin-D, and not via its involvement in the production of the cytokines IL-1 and/or IL-18. Consistent with a role for this sensor of genomic stress in the purging of genetically compromised CNS cells, we find that defective AIM2 inflammasome signalling results in decreased neural cell death both in response to DNA damage-inducing agents and during neurodevelopment. Moreover, mutations in AIM2 lead to excessive accumulation of DNA damage in neurons as well as an increase in the number of neurons that incorporate into the adult brain. Our findings identify the inflammasome as a crucial player in establishing a properly formed CNS through its role in the removal of genetically compromised cells.