The CBL Knockout NCI-H1975 Polyclonal Cells constitute a CRISPR/Cas9-edited polyclonal knockout cell population generated from the NCI-H1975 human lung adenocarcinoma line, engineered to disrupt the endogenous CBL locus. This format provides a population-level gene knockout model, enabling functional studies without clonal selection bias.
The parental NCI-H1975 cell line originates from a human lung adenocarcinoma and harbors clinically relevant EGFR mutations (L858R and T790M) as well as a PIK3CA mutation. The EGFR L858R/T790M genotype confers oncogenic signaling and mediates resistance to first-generation EGFR tyrosine kinase inhibitors, while the concurrent PIK3CA mutation activates the PI3K-AKT pathway. These genetic features establish NCI-H1975 as a pertinent model for studying EGFR-targeted therapy resistance and lung adenocarcinoma pathogenesis.
CBL encodes an E3 ubiquitin ligase that serves as a negative regulator of receptor tyrosine kinase (RTK) signaling. Upon activation by SRC family kinases and phosphorylation, CBL binds directly to activated RTKs such as EGFR, PDGFR, and MET via its phosphotyrosine-binding domain and adaptor proteins including GRB2. It then associates with UBE2D/UBCH5 family E2 ubiquitin-conjugating enzymes to catalyze polyubiquitination of the receptor, targeting it for lysosomal degradation and thereby attenuating downstream cascades. Consequently, disruption of CBL relieves this negative feedback, resulting in sustained activation of the MAPK pathway (EGFR?CGRB2?CSOS?CRAS?CRAF?CMEK?CERK) and the PI3K-AKT axis. CBL also interacts with CIN85 to regulate endocytosis, further modulating signal duration.
In the NCI-H1975 background, CBL knockout may exacerbate EGFR-driven oncogenic signaling, providing a disease-relevant platform to investigate resistance mechanisms. Since the EGFR T790M mutation impedes inhibitor binding, and PIK3CA mutations stimulate parallel survival pathways, loss of CBL-mediated EGFR degradation can further potentiate downstream signaling, mimicking scenarios encountered in relapsed lung adenocarcinoma. This model thus facilitates the study of how disrupted RTK ubiquitination contributes to tumor progression and drug tolerance, and enables the assessment of therapeutic strategies targeting the CBL?CRTK interface.
Researchers can employ this polyclonal knockout pool in a broad array of assays, including Western blotting and ubiquitination assays to monitor EGFR and CBL protein status, co-immunoprecipitation to interrogate protein?Cprotein interactions, and RT-qPCR to profile pathway transcriptional changes. Functional outcomes can be assessed via cell proliferation, flow cytometry, and drug sensitivity screens testing EGFR inhibitors or other targeted agents. The population-level knockout provides a convenient tool for investigating CBL-mediated ubiquitination in lung cancer, exploring EGFR inhibitor resistance, and screening for compounds that exploit synthetic lethality with CBL loss. For further technical specifications or to inquire about this product, please contact Ascent Research.
