The CD274 Knockout CAL-27 Polyclonal Cells comprise a CRISPR/Cas9-edited polyclonal cell population derived from the CAL-27 human tongue squamous cell carcinoma line, engineered for targeted disruption of the CD274 gene. This polyclonal knockout product provides a heterogeneous pool of loss-of-function alleles, enabling functional studies without clonal selection artifacts. The CRISPR/Cas9-mediated gene disruption generates a versatile model for investigating PD-L1 biology in an oral cancer context.
The parental CAL-27 cell line originates from a squamous cell carcinoma of the tongue and serves as a well-characterized model for head and neck cancers, particularly oral squamous cell carcinoma. These adherent epithelial cells retain key genetic and phenotypic features of the tumor of origin, including expression of relevant oncogenic drivers and immune modulatory molecules. CAL-27 is frequently employed in cancer biology and immunotherapy research due to its reproducible growth characteristics and susceptibility to genetic manipulation.
CD274 encodes programmed death-ligand 1 (PD-L1), an immune checkpoint protein that engages the PD-1 receptor on T cells. Upon binding, PD-L1 recruits SHP2 phosphatase, which dephosphorylates proximal TCR signaling kinases such as ZAP70 and LCK, thereby inhibiting T cell activation and promoting immune evasion. PD-L1 expression is transcriptionally induced by IFN-gamma through JAK/STAT signaling and is further modulated by upstream regulators including MYC, HIF1A, NF-kB, and EGFR pathways. CD274 also interacts with CD80 and is stabilized by CMTM6 and CMTM4, integrating diverse signals that control the immunosuppressive tumor microenvironment.
In the CAL-27 oral cancer model, abrogation of CD274 expression disrupts the PD-L1/PD-1 immune checkpoint axis, directly impairing the tumor cell’s ability to suppress T cell responses. This knockout model enables dissection of PD-L1-mediated immune escape mechanisms specifically within squamous cell carcinoma of the head and neck, where PD-L1 overexpression correlates with poor prognosis. The polyclonal population reflects heterogeneous gene disruption, mimicking the genetic variability seen in tumors and providing a robust system for studying outgrowth under immune selective pressure.
This CD274 knockout polyclonal cell product is ideally suited for a broad range of immunoncology applications, including co-culture T cell killing assays to evaluate tumor cell susceptibility, flow cytometric assessment of PD-L1 surface loss, and PD-1/PD-L1 binding inhibition studies. Researchers can also employ IFN-gamma stimulation to probe JAK/STAT pathway integrity, STAT1/STAT3 phosphorylation analysis by western blotting, and drug sensitivity profiling with anti-PD-L1 or anti-PD-1 checkpoint inhibitors. Additional uses include RT-qPCR quantification of CD274 mRNA and immunofluorescence localization of PD-L1. Such experiments support the development of next-generation immunotherapies and investigation of drug resistance mechanisms. For further information, please contact Ascent Research.
