Identify the role of host ATF4 on CAFs in the tumor microenvironment of small size B16F10 tumors

To delineate the role of host ATF4 in the sequence of events leading to tumor growth, we performed transcriptional profiling at the single-cell level (scRNA-seq) in smaller (150 mm3) size B16F10 tumors grown in Atf4wt/wt and Atf4D/D mice. Among others, we observed striking differences in gene expression in a cluster that corresponds to CAFs. In this cluster, we identified 148 DE genes, including a significant downregulation of Col1a1 and Col1a2 in the Atf4D/D mice-grown tumors. Notably, the expression levels of aSMA and Pdgfrb were nearly absent in the tumors grown in Atf4D/D mice. Finally, after CAFs subclustering, we identified the vCAFs (vascular CAFs) that are considered essential for vascular development and angiogenesis to be significantly reduced in the Atf4D/D mice. Overall design: Smaller size B16F10 tumors from two Atf4wt/wt and two Atf4D/D were harvested, pulled and submitted for scRNA-seq analysis.