Single-cell transcriptome analysis reveals dynamic changes of the preclinical A549 cancer models, and the mechanism of dacomitinib.

The in vitro A549 cells, and A549 xenografts in nude mouse, were two commonly used models for anti-cancer drug discovery. However, the biological and molecular characteristics of these two classic models, and also the dynamic transcriptome changes after dacomitinib exposure remains elusive. We performed single-cell RNA sequencing to define the transcriptome profile at single-cell resolution, and processed tumor samples for bulk RNA and protein analysis to validate the differently expressed genes. Transcriptome profiling revealed that the in vitro A549 cells are heterogeneous. The minimal subpopulation of the in vitro A549 cells, which were characterized by the signature of response to unfolded protein, became the overriding subpopulation of the xenografts. The EGFR non-activating A549 cells were resistant to dacomitinib in vitro, while A549 xenografts were comparatively sensitive as EGFR-activating HCC827 xenografts. Dacomitinib inhibited MAPK signaling pathway, and increased the immune response in the A549 xenografts. A phagocytosis checkpoint stanniocalcin-1 (STC1) was significantly inhibited in dacomitinib-treated xenografts. So here our study gives the first insight of the heterogeneity of the two classic models, and the translational potential of dacomitinib being used into a broader patient population rather than EGFR common activating mutation.

Quantitative proteomic analysis of the effects of dietary deprivation of methionine and cystine on A549 xenograft and A549 xenograft-bearing mouse.

Methionine (Met) and cystine (CySS) are key sulfur donors in cell metabolism and are important nutrients for sustaining tumor growth; however, the molecular effects associated with their deprivation remain to be characterized. Here, we applied a xenograft mouse model to assess the impact of their deprivation on A549 xenografts and the xenograft-bearing animal. Results show that Met and CySS deprivation inhibits A549 growth in vitro, not in vivo. Deprivation was detrimental to the xenograft-bearing mouse, as demonstrated by weight loss and renal dysfunction. Differentially expressed proteins in A549 xenograft and mouse kidneys were characterized using quantitative proteomics. Functional annotation and protein-protein interaction network analysis revealed the enriched signaling pathways, including focal adhesion (Fn1) in the A549 xenograft, and xenobiotic metabolism (Cyp2e1) and glutathione metabolism (Ggt1) in the mouse kidney. Met and CySS deprivation inhibits the migratory and invasive properties of cancer cells, as evidenced by reduced expression of the epithelial to mesenchymal transition marker N-cadherin in A549 cells in vitro. Moreover, IGFBP1 protein expression was inhibited in both A549 xenograft and mouse kidneys. This study provides the first insights into changes within the proteome profile and biological processes upon Met and CySS deprivation in a A549 xenograft mouse model.