CD274 Knockout A-549 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the A-549 human lung adenocarcinoma cell line. This product provides a targeted loss-of-function model for CD274, the gene encoding programmed death-ligand 1 (PD-L1). CRISPR/Cas9-mediated disruption of CD274 eliminates endogenous PD-L1 expression, enabling researchers to investigate the functional consequences of PD-L1 ablation without interference from wild-type protein. As a polyclonal pool, this knockout model retains genetic heterogeneity while collectively lacking PD-L1, making it suitable for population-level studies of immune checkpoint modulation.
The A-549 cell line was established from explanted lung carcinoma tissue of a 58-year-old Caucasian male and serves as a well-characterized model for type II alveolar epithelium and non-small cell lung cancer (NSCLC). These adherent epithelial cells exhibit hallmarks of adenocarcinoma, including rapid proliferation, tumorigenicity in xenograft models, and responsiveness to various cytokines and growth factors. A-549 cells are widely employed to study lung cancer biology, drug metabolism, and oncogenic signaling. Notably, they express basal levels of PD-L1 that are markedly upregulated by interferon gamma (IFNG) stimulation, mirroring the immune adaptive resistance observed in clinical NSCLC. This makes the A-549 background particularly relevant for investigating PD-L1-dependent immune evasion mechanisms.
CD274 encodes PD-L1, a transmembrane immune checkpoint protein that binds to the PD-1 receptor (encoded by PDCD1) on activated T cells to suppress anti-tumor immunity. Engagement of PD-1 by PD-L1 recruits SHP2 phosphatase (PTPN11), which dephosphorylates key proximal T-cell receptor signaling molecules such as ZAP70 and LCK, thereby attenuating downstream PI3K/AKT, ERK, and mTOR pathways and inhibiting T-cell activation and effector functions. Additionally, PD-L1 can interact with B7-1 (CD80) to further modulate immune responses, and it forms homodimers on the tumor cell surface. In the A-549 context, CD274 transcription is driven by upstream regulators including IFNG-induced STAT1, STAT3, NFKB1 (p50/p65), MYC, and HIF1A, while PTEN loss and ALK fusion can also enhance PD-L1 expression. Consequently, disruption of CD274 removes this inhibitory axis, allowing restoration of proximal T-cell signaling and anti-tumor cytotoxicity.
In A-549 lung adenocarcinoma cells, PD-L1 plays a central role in immune escape by inhibiting cytotoxic T lymphocyte activity within the tumor microenvironment. Knockout of CD274 in this polyclonal population creates a unique tool for dissecting how NSCLC tumors avoid immune destruction, particularly when challenged with tumor-infiltrating lymphocytes or engineered chimeric antigen receptor (CAR) T cells. The lack of PD-L1 eliminates the dominant checkpoint signal, enabling the study of compensatory immune evasion pathways and the evaluation of combination immunotherapies targeting additional checkpoints or suppressive factors. Moreover, this model facilitates the assessment of PD-L1-independent effects of drugs and cytokines on A-549 cell survival, migration, and proliferation, providing a clean background for mechanistic studies.
The CD274 Knockout A-549 Polyclonal Cells are suitable for a broad spectrum of research applications. They can be used in T-cell co-culture cytotoxicity assays to measure tumor killing in the absence of PD-1/PD-L1 interaction, as well as in flow cytometry and Western blotting to confirm PD-L1 ablation and analyze downstream signaling pathways. Researchers can validate anti-PD-L1 antibody specificity and screen small-molecule PD-L1 inhibitors using drug sensitivity and migration assays. Additionally, IFNG stimulation experiments can probe cytokine-mediated gene expression changes independent of PD-L1 feedback. For further information or technical inquiries, please contact Ascent Research.
