The KSR1 Knockout NCI-H1975 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout population derived from NCI-H1975 lung adenocarcinoma epithelial cells. This loss-of-function model targets the KSR1 gene, encoding a scaffold protein essential for RAS-RAF-MEK-ERK signal transduction. Generated via CRISPR/Cas9-mediated gene disruption, the polyclonal pool provides a heterogeneous cell population for robust functional studies without clonal isolation. It enables investigation of oncogenic MAPK signaling in EGFR-mutant non-small cell lung cancer.
NCI-H1975 is a female lung adenocarcinoma epithelial cell line from a metastatic pleural effusion, harboring EGFR L858R and T790M mutations. These clinically relevant mutations drive EGFR-dependent signaling and confer resistance to first- and second-generation TKIs, making NCI-H1975 a key model for studying acquired drug resistance and tumor progression in lung cancer. The cells exhibit persistent MAPK pathway activation due to mutant EGFR, offering a relevant context for analyzing downstream effector functions.
KSR1 functions as a kinase scaffold that colocalizes RAF, MEK, and ERK to facilitate their sequential phosphorylation. It is regulated by EGFR-RAS signals and interacts with 14-3-3 proteins, HSP90, and CK2. KSR1 binds RAF isoforms (A-RAF, B-RAF, C-RAF), MEK1/2, and ERK1/2, thereby optimizing signal propagation to downstream effectors such as ELK1, c-FOS, c-JUN, and Cyclin D1. By enabling efficient MAPK cascade activation, KSR1 transmits oncogenic signals from receptor tyrosine kinases to transcriptional and cell cycle machinery.
In NCI-H1975 cells, constitutively active EGFR L858R/T790M hyperactivates the MAPK pathway, promoting proliferation and survival. KSR1 knockout disrupts scaffold-mediated assembly, uncoupling RAF-MEK-ERK signaling despite upstream oncogenic input. This provides a controlled system to dissect scaffold-dependent vulnerabilities and evaluate the therapeutic impact of targeting signaling adaptors in EGFR-mutant lung cancer. The polyclonal knockout population reflects tumor heterogeneity, enhancing physiological relevance for drug response studies.
Applications include investigating EGFR TKI resistance, scaffold contributions to oncogenesis, synthetic lethal screens, and drug target validation. Compatible assays encompass western blotting for phospho-ERK, cell viability with osimertinib or erlotinib, proliferation, colony formation, migration/invasion, RNA-seq, and co-immunoprecipitation of KSR1-RAF complexes. This model supports preclinical studies in non-small cell lung cancer research. For further information, please contact Ascent Research.
