The CBX6 Knockout NCI-H1975 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal population derived from the NCI-H1975 non-small cell lung adenocarcinoma cell line, with targeted disruption of the CBX6 gene. This loss-of-function model enables detailed investigation of CBX6-dependent epigenetic mechanisms in a genetic background carrying the clinically relevant EGFR L858R/T790M double mutation. The polyclonal format avoids clonal selection biases and preserves functional diversity, facilitating robust, population-level phenotypic assessments of chromatin silencing, proliferation control, and drug response.
The parental NCI-H1975 line is an adherent epithelial cell model isolated from a human lung adenocarcinoma, extensively employed to study EGFR-mutant non-small cell lung cancer (NSCLC) progression and acquired resistance to tyrosine kinase inhibitors (TKIs) such as osimertinib. The co-occurrence of the L858R activating mutation and the T790M gatekeeper mutation mirrors a frequent clinical resistance paradigm, rendering this line highly relevant for translational oncology and drug discovery efforts. These cells maintain stable morphology and are amenable to gene-editing and high-throughput screening.
CBX6 is a core component of Polycomb repressive complex 1 (PRC1), functioning as a reader of trimethylated histone H3 at lysine 27 (H3K27me3) through its chromodomain. This interaction drives chromatin compaction and stable transcriptional silencing of PRC target genes. CBX6 assembles into multimeric complexes with RING1A/RING1B, BMI1, and PHC proteins, and its activity is governed by upstream regulators including E2F transcription factors, BMI1, and MAPK/ERK signaling. Downstream, CBX6 represses the cyclin-dependent kinase inhibitors CDKN1A (p21) and CDKN2A (p16), as well as HOX gene clusters, AXIN2, and SOX2, thereby connecting Polycomb silencing to p53/p21 and Wnt/??-catenin pathways that govern cell cycle arrest, differentiation, and senescence.
In the EGFR-mutant NCI-H1975 background, CBX6 knockout is predicted to derepress tumor-suppressive and prodifferentiation genes, potentially reinstating senescence-like growth arrest and modulating sensitivity to EGFR TKI therapy. Given that PRC1-mediated silencing is often dysregulated in lung adenocarcinoma, this model is well-suited to dissect epigenetic contributions to drug-tolerant persister states and acquired resistance. The combinatorial effect of CBX6 loss and oncogenic EGFR signaling may uncover synthetic vulnerabilities or predictive markers for epigenetic therapies.
This product supports diverse applications, including cell proliferation and clonogenic assays, apoptosis detection by Annexin V staining, and osimertinib dose?Cresponse studies to evaluate TKI sensitivity. Molecular analyses encompass ChIP-qPCR for H3K27me3 enrichment, transcriptome-wide RNA-seq, and western blotting for CBX6, p21, and p16. Senescence-associated beta-galactosidase staining can detect senescence induction. The cells also enable validation of CBX6-targeted small molecules or PROTACs and functional complementation experiments. For additional technical information, please contact Ascent Research.
