The CD274 Knockout 143B Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the human 143B osteosarcoma cell line, featuring disruption of the CD274 gene encoding PD-L1. This polyclonal pool contains cells with heterogeneous CRISPR-induced edits at the target locus, enabling loss-of-function analysis without clonal selection. The format avoids single-cell cloning bias and provides a broad cellular context for studying PD-L1 biology and immune checkpoint function.
143B is a thymidine kinase-deficient subline of HOS, a widely used human osteosarcoma model. These cells are highly tumorigenic and metastatic, making them valuable for investigating bone cancer progression and metastatic dissemination. The aggressive phenotype, combined with typical osteosarcoma pathway alterations, establishes a relevant system for examining tumor-immune interactions and the impact of checkpoint molecule disruption.
CD274 (PD-L1) encodes a transmembrane ligand that engages PD-1 on T cells, recruiting SHP-1 and SHP-2 phosphatases to the TCR complex. This dephosphorylates ZAP70 and attenuates PI3K-AKT and ERK signaling, leading to suppression of T cell proliferation, cytokine production, and cytotoxicity. PD-L1 expression is driven by IFN-?? via JAK-STAT, TLR agonists, and oncogenic signals including MYC, ALK, EGFR, PTEN loss, and HIF-1??. PD-L1 also interacts with CD80, delivering co-inhibitory signals. Core pathway components include PD-1, SHP-1/2, ZAP70, PI3K, AKT, and ERK.
In 143B osteosarcoma cells, CD274 knockout provides a disease-relevant model to dissect tumor-intrinsic PD-L1 contributions to immune escape. Osteosarcomas upregulate PD-L1 under cytokine or oncogenic stress, correlating with poor outcomes. Disruption of CD274 allows clear discrimination of PD-L1-dependent immune suppressive mechanisms within a bone-mimetic microenvironment and is particularly useful for studying lymphocyte interactions and validating immune reactivation strategies.
These cells support applications in cancer immunotherapy, immune checkpoint blockade, and tumor microenvironment research. Co-culture T cell assays can assess recovery of proliferation, cytokine secretion, and cytotoxicity upon PD-L1 loss. Validation methods include flow cytometry, western blotting, RT-qPCR, and immunofluorescence. PD-1 binding and checkpoint inhibitor sensitivity assays facilitate drug candidate evaluation. The polyclonal format suits high-throughput screening and functional genomics. For further information or custom applications, contact Ascent Research.
