The CCNT2 Knockout NCI-H1975 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout population targeting the human CCNT2 gene in NCI-H1975 lung adenocarcinoma cells. This heterogeneous pool provides a loss-of-function model for Cyclin T2, the regulatory subunit of the P-TEFb complex, enabling functional studies in a cancer-relevant context without clonal selection biases. The knockout cell population supports robust transcriptional and cellular assays and is ready for immediate use in downstream applications.
The parental NCI-H1975 cell line is a well-characterized model of non-small cell lung carcinoma (NSCLC) from a female non-smoker. It harbors activating EGFR L858R and resistance T790M mutations, driving constitutive signaling and resistance to first-generation tyrosine kinase inhibitors. These epithelial cells retain key adenocarcinoma features, making them a valuable platform for cancer biology and drug testing.
Cyclin T2, encoded by CCNT2, partners with CDK9 to form P-TEFb, which is dynamically regulated by association with the 7SK snRNP (HEXIM1, LARP7). Release from 7SK, triggered by CDK7 phosphorylation and BRD4 recruitment, activates P-TEFb to phosphorylate serine 2 of the RNA polymerase II C-terminal domain. This releases paused polymerases, promoting elongation of targets like MYC, FOS, CCND1, and NR4A1. CCNT2 knockout impairs P-TEFb activity, disrupting expression of these proliferation and survival genes. The Cyclin T2/CDK9 complex also interfaces with the super elongation complex (SEC), including AFF4, to coordinate rapid transcriptional responses.
In EGFR-mutant NCI-H1975 cells, CCNT2 disruption attenuates P-TEFb-dependent transcription, reducing growth-promoting and anti-apoptotic signals, which sensitizes cells to transcriptional stress and apoptosis. This reveals a potential therapeutic vulnerability exploitable by CDK9 inhibitors in NSCLC. The model enables discrimination of Cyclin T2-specific functions from Cyclin T1 and supports studies of transcriptional addiction and resistance mechanisms. It provides a physiologically relevant system for evaluating CDK9-targeted therapies in lung adenocarcinoma.
Researchers can employ these polyclonal knockout cells to investigate P-TEFb-mediated transcriptional elongation using ChIP-qPCR for RNA polymerase II occupancy, assess CDK9 inhibitor sensitivity via proliferation and apoptosis assays, and profile transcriptomic changes by RNA-seq. Additional applications include western blotting, RT-qPCR, immunofluorescence, and drug combination studies. The model is well-suited for target validation and synthetic lethality screening in NSCLC. For technical protocols and support, please contact Ascent Research.
