FACS-Based Genome-Wide CRISPR Screening Platform Identifies Modulators of CD47
CD47 is a key innate immune checkpoint that enables tumor cells to evade macrophage-mediated clearance. To systematically identify genetic regulators of CD47 surface expression, we performed FACS-based genome-wide CRISPR screens in three murine cancer cell lines, B16 (melanoma), MC38 (colon adenocarcinoma), and EMT6 (breast carcinoma). Comparative analysis of cells with high or low CD47 surface expression using DrugZ revealed CD47 itself as the top hit, validating the screens. Notably, DNAJC13 emerged as a consistent and robust regulator of CD47 expression across all three cell lines. Functional validation using DNAJC13-knockout cells confirmed a significant reduction in CD47 surface levels. Furthermore, in co-culture assays with macrophages, DNAJC13-deficient tumor cells exhibited increased susceptibility to phagocytosis, supporting a functional role for DNAJC13 in innate immune evasion. Finally, we verify that DNAJC13-knockout decrease tumor burden when treated with CD47 blockade. Overall, this study highlights a previously unrecognized regulator of CD47 and demonstrates the utility of high-throughput FACS-based CRISPR screening to uncover modulators of key immune checkpoint pathways. Overall design: mouse whole genome FACS-based CRISPR-Cas9 knock out screenings in three mouse cancer cell lines: B16F10A,  MC38 and EMT6.