The GRB7 Knockout NCI-H1975 Polyclonal Cells represent a polyclonal knockout cell population generated by CRISPR/Cas9-mediated disruption of the GRB7 gene in the NCI-H1975 human lung adenocarcinoma cell line. This heterogeneous pool carries diverse loss-of-function mutations at the target locus, minimizing clonal artifacts and providing a physiologically relevant model for investigating GRB7-dependent oncogenic processes. The cells are supplied as a ready-to-use tool, facilitating rigorous dissection of signaling networks.
The NCI-H1975 parental line, derived from metastatic pleural effusion of a female with non-small cell lung carcinoma, is an adherent epithelial cell line harboring both EGFR L858R and T790M mutations. These driver mutations sustain constitutive activation of the receptor tyrosine kinase and confer resistance to first-generation EGFR inhibitors, positioning NCI-H1975 as a well-established preclinical model for studying advanced EGFR-mutant lung adenocarcinoma and drug resistance mechanisms.
GRB7 encodes a cytoplasmic adaptor protein that selectively binds phosphorylated tyrosines on activated ERBB2 and EGFR receptors. Through its SH2 domain, GRB7 directly interacts with these receptors and facilitates the assembly of SOS-Ras guanine nucleotide exchange factor complexes and focal adhesion kinase (FAK). This triggers two key cascades: the RAS-RAF-MEK-ERK mitogen-activated protein kinase pathway and the PI3K-AKT axis, modulated by upstream regulators including EGF, NRG1, and Src kinase. Downstream, GRB7-driven signals promote ERK1/2 and AKT phosphorylation, FAK activation, and upregulation of cyclin D1 and Snail, collectively enhancing proliferation, migration, and survival. Additional interacting proteins such as SHC and the Ras GTPase-activating protein RasGAP further refine signal output.
Within the NCI-H1975 context, the L858R/T790M mutations confer hyperactivation of EGFR signaling, rendering the cells highly dependent on GRB7-mediated signal transduction. CRISPR/Cas9-mediated disruption of GRB7 uncouples ERBB2 and EGFR from SOS-Ras and FAK, leading to diminished phosphorylation of ERK and AKT and reduced expression of cyclin D1 and Snail. This attenuation disrupts downstream oncogenic programs, resulting in decreased proliferation, anchorage-independent growth, and invasive capacity. The polyclonal knockout model thus provides an isogenic system to dissect the contribution of GRB7-dependent pathways to TKI resistance and to uncover adaptive signaling nodes sustaining EGFR-mutant lung adenocarcinoma.
These polyclonal knockout cells support a wide range of applications, including Western blot analysis of phospho-ERK and phospho-AKT, RT-qPCR profiling, cell proliferation assays (MTS/XTT), transwell migration/invasion assays, and colony formation studies. They are also suitable for tumor xenograft experiments, RNA-sequencing to map GRB7-dependent transcriptional networks, and co-immunoprecipitation to assess protein interactions within the ERBB2/EGFR signalosome. Furthermore, they facilitate synthetic lethality screens and the rational design of combination therapies targeting residual oncogenic pathways. For additional technical details or assistance, researchers are encouraged to contact Ascent Research.
