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Little is known of the geospatial architecture of individual cell populations in lung adenocarcinoma (LUAD) evolution. Here, we perform single-cell RNA sequencing of 186,916 cells from five early-stage LUADs and 14 multiregion normal lung tissues of defined spatial proximities from the tumors. We show that cellular lineages, states, and transcriptomic features geospatially evolve across normal regions to LUADs. LUADs also exhibit pronounced intratumor cell heterogeneity within single sites and transcriptional lineage-plasticity programs. T regulatory cell phenotypes are increased in normal tissues with proximity to LUAD, in contrast to diminished signatures and fractions of cytotoxic CD8+ T cells, antigen-presenting macrophages, and inflammatory dendritic cells. We further find that the LUAD ligand-receptor interactome harbors increased expression of epithelial CD24, which mediates protumor phenotypes. These data provide a spatial atlas of LUAD evolution, and a resource for identification of targets for its treatment. SIGNIFICANCE: The geospatial ecosystem of the peripheral lung and early-stage LUAD is not known. Our multiregion single-cell sequencing analyses unravel cell populations, states, and phenotypes in the spatial and ecologic evolution of LUAD from the lung that comprise high-potential targets for early interception.This article is highlighted in the In This Issue feature, p. 2355.

The pleiotropic effect of cancer‐associated fibroblasts (CAFs) on tumour progression depends on the environment. circFARP1 is critical for CAFs‐induced gemcitabine (GEM) resistance in pancreatic cancer. Its specific role and mechanism in non–small cell lung cancer (NSCLC) have not been reported yet. We prepared a cancer‐associated fibroblasts‐conditioned medium (CAF‐CM) to incubate the A549 cells. Quantitative real‐time polymerase chain reaction was used to detect RNA levels. We detected protein expression by immunohistochemistry, immunocytochemistry, western blot and immunofluorescence. We also detected the targeting impact between circFARP1, miR‐338‐3p and SRY‐box transcription factor 4 (SOX4) by using dual‐luciferase reporter and RNA pull‐down assays. We determined cell proliferation, migration and invasion capabilities through Cell Counting Kit‐8 and transwell assays. In addition, we measured tumour volume and weight in vivo by establishing a xenograft tumour model. CircFARP1 levels were remarkably high in the CAFs. The transfection experiments found that circFARP1 downregulation in CAFs caused migration, proliferation and invasion inhibition of CAFs and A549 cells, whereas inhibiting miR‐38‐3p or overexpressing SOX4 in CAFs could significantly reverse the inhibition. In vivo study in nude mice confirmed that CAFs could promote NSCLC tumour growth and knockdown of circFARP1 could inhibit tumour growth of NSCLC, whereas miR‐38‐3p downregulation or SOX4 overexpression could significantly reverse the inhibition. circFARP1 promotes NSCLC development by stimulating miR‐338‐3p/SOX4 signalling axis to regulate CAFs. [ABSTRACT FROM AUTHOR]

Using finite element simulation and single-variable experimental methods, this study analyzes the variations in the microstructure and hardness of a 304 stainless steel wire during Joule heating fused filament fabrication. The effects of current intensity, printing speed, and roller pressure on the macroscopic morphology, microstructure, and microhardness of a single-layer single-channel formation were investigated. The results indicate that when the current intensity is 400 A, the printing speed is 1000 mm/min, and the roller pressure is 0.3 N, the surface of the single-layer single-channel formation is smooth and exhibits optimal forming characteristics with a width-to-height ratio of 3.23, a dilution rate of 51.61%, and an average microhardness of 238.17 HV. As the current intensity increases, the microstructure in the fusion zone initially decreases in size and then increases; similarly, with the increase in printing speed, the microstructure in the fusion zone first decreases and then increases; as the roller pressure increases, the microstructure in the fusion zone initially increases in size and then decreases. The microhardness initially increases and then decreases with the increase in process parameters, resulting in uneven hardness distribution due to the variations in microstructure size. The optimal combination of process parameters achieves a balance between heat input, cooling rate, and growth rate, thereby achieving grain refinement and hardness improvement, ultimately enhancing the mechanical properties of the material. [ABSTRACT FROM AUTHOR]

Cell plasticity theoretically extends to all possible cell types, but naturally decreases as cells differentiate, whereas injury-repair re-engages the developmental plasticity. Here we show that the lung alveolar type 2 (AT2)-specific transcription factor (TF), CEBPA, restricts AT2 cell plasticity in the mouse lung. AT2 cells undergo transcriptional and epigenetic maturation postnatally. Without CEBPA, both neonatal and mature AT2 cells reduce the AT2 program, but only the former reactivate the SOX9 progenitor program. Sendai virus infection bestows mature AT2 cells with neonatal plasticity where Cebpa mutant, but not wild type, AT2 cells express SOX9, as well as more readily proliferate and form KRT8/CLDN4+ transitional cells. CEBPA promotes the AT2 program by recruiting the lung lineage TF NKX2-1. The temporal change in CEBPA-dependent plasticity reflects AT2 cell developmental history. The ontogeny of AT2 cell plasticity and its transcriptional and epigenetic mechanisms have implications in lung regeneration and cancer. Cell plasticity underlies development and regeneration. Here, the authors show that mouse lung alveolar type 2 cells undergo maturation postnatally and their plasticity is restricted by CEBPA and increases upon viral infection. [ABSTRACT FROM AUTHOR]

Airway mucin secretion is important pathophysiologically and as a model of polarized epithelial regulated exocytosis. We find the trafficking protein, SNAP23 (23-kDa paralogue of synaptosome-associated protein of 25 kDa), selectively expressed in secretory cells compared with ciliated and basal cells of airway epithelium by immunohistochemistry and FACS, suggesting that SNAP23 functions in regulated but not constitutive epithelial secretion. Heterozygous SNAP23 deletant mutant mice show spontaneous accumulation of intracellular mucin, indicating a defect in baseline secretion. However mucins are released from perfused tracheas of mutant and wild-type (WT) mice at the same rate, suggesting that increased intracellular stores balance reduced release efficiency to yield a fully compensated baseline steady state. In contrast, acute stimulated release of intracellular mucin from mutant mice is impaired whether measured by a static imaging assay 5 min after exposure to the secretagogue ATP or by kinetic analysis of mucins released from perfused tracheas during the first 10 min of ATP exposure. Together, these data indicate that increased intracellular stores cannot fully compensate for the defect in release efficiency during intense stimulation. The lungs of mutant mice develop normally and clear bacteria and instilled polystyrene beads comparable to WT mice, consistent with these functions depending on baseline secretion that is fully compensated.