The Cd274 Knockout MDA-MB-231 Cell Line is a CRISPR/Cas9-edited knockout cell line engineered to abolish PD-L1 expression through targeted disruption of the Cd274 gene in the human triple-negative breast cancer cell line MDA-MB-231. This model provides a stable loss-of-function system for investigating PD-L1 biology, enabling researchers to dissect its role in immune checkpoint regulation and tumor immune evasion.
The parental MDA-MB-231 cell line is an epithelial cell line derived from a pleural effusion of a patient with metastatic mammary adenocarcinoma. It is characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and HER2 amplification, classifying it as triple-negative breast cancer (TNBC)??a subtype with poor prognosis and limited targeted therapies. MDA-MB-231 cells are highly invasive and metastatic, exhibiting a mesenchymal-like phenotype, and are widely employed in studies of cancer cell migration, invasion, and metastasis.
CD274 encodes PD-L1 (programmed death-ligand 1), a transmembrane immune checkpoint ligand that binds to PD-1 (PDCD1) on activated T cells. This interaction recruits SHP2 phosphatase, which dephosphorylates key signaling molecules downstream of the T-cell receptor (TCR), including ZAP70 and PI3K, thereby attenuating AKT and ERK activation. The resulting suppression of TCR signaling leads to T-cell exhaustion and impaired anti-tumor immunity. PD-L1 also interacts with CD80 (B7-1), providing an additional inhibitory signal. Expression of CD274 is tightly regulated by inflammatory cytokines such as interferon-gamma (IFNG) and transcription factors including MYC, HIF1A, and NF-??B. Additionally, oncogenic pathways like EGFR signaling and loss of the tumor suppressor PTEN are associated with PD-L1 upregulation.
In the MDA-MB-231 TNBC context, PD-L1 overexpression contributes to the establishment of an immunosuppressive tumor microenvironment, facilitating immune escape. Knockout of Cd274 enables precise investigation of PD-L1-dependent immune modulation, including effects on T-cell activation, cytokine secretion, and tumor cell-intrinsic signaling pathways such as JAK-STAT and PI3K-AKT. This model is pivotal for elucidating mechanisms of immune resistance in TNBC and for validating therapeutic strategies that target the PD-1/PD-L1 axis.
Representative applications include flow cytometry and immunofluorescence to confirm abrogation of PD-L1 surface expression; RT-qPCR and western blotting to quantify Cd274 transcript and protein levels; co-culture T-cell suppression assays to measure functional restoration of T-cell activity; real-time monitoring of T-cell-mediated killing; migration and invasion assays to assess metastatic potential in the absence of PD-L1 signaling; and drug sensitivity profiling with anti-PD-L1 antibodies or small-molecule checkpoint inhibitors. Furthermore, this cell line supports high-content screening of immunomodulatory compounds and studies of adaptive resistance mechanisms. For further technical details, please contact Ascent Research.
