The CBS Knockout NCI-H1975 Polyclonal Cells consist of a CRISPR/Cas9-edited polyclonal population of human NCI-H1975 lung adenocarcinoma epithelial cells carrying a targeted disruption of the CBS gene. This heterogeneous knockout pool provides a reliable loss-of-function model for investigating the transsulfuration pathway without clonal isolation, enabling studies of gene function in a polyclonal background that retains natural population diversity.
The NCI-H1975 cell line was established from the pleural effusion of a female patient with non-small cell lung cancer and harbors activating EGFR L858R and T790M mutations. These mutations confer resistance to first-generation EGFR tyrosine kinase inhibitors, making it a key model for EGFR-mutant lung adenocarcinoma with acquired drug resistance. The cells retain epithelial morphology and are widely used to explore metabolic adaptations underlying resistance.
CBS encodes cystathionine ??-synthase, a heme-containing homotetramer that catalyzes the condensation of homocysteine and serine to cystathionine in the transsulfuration pathway, an irreversible step that directs homocysteine toward cysteine and hydrogen sulfide (H2S) synthesis. The enzyme is allosterically activated by S-adenosylmethionine and transcriptionally regulated by SP1, NF-??B, and hypoxia-inducible factor-1?? (HIF-1??). Key downstream products include cysteine, glutathione, taurine, and H2S, which acts as a gasotransmitter modulating redox signaling. CBS physically interacts with methionine synthase and the scaffold protein p62, integrating methionine cycle flux with transsulfuration.
Disruption of CBS in NCI-H1975 cells provides a powerful tool to dissect the role of the transsulfuration pathway in EGFR-mutant lung adenocarcinoma. These tumor cells depend on robust antioxidant defenses to counteract oncogene-driven oxidative stress and drug resistance. Loss of CBS can impair cysteine and glutathione production, potentially sensitizing cells to oxidative damage and altering H2S-mediated signaling. Consequently, this model supports investigations into how homocysteine metabolic partitioning influences tumor cell proliferation, apoptosis, and treatment response.
Typical research applications include studying lung cancer metabolism, homocysteine pathophysiology, redox homeostasis, drug resistance mechanisms, and hydrogen sulfide signaling. Representative assays encompass western blotting for CBS protein, liquid chromatography-mass spectrometry measurement of cystathionine, hydrogen sulfide fluorescence assays, homocysteine ELISA, and cell viability assessments under oxidative stress. The polyclonal knockout population is well-suited for metabolic flux analysis, pathway rewiring studies, and synthetic lethality screens. For additional details or custom cell engineering inquiries, please contact Ascent Research.
