The CCNT1 Knockout NCI-H1975 Polyclonal Cells product comprises a heterogeneous population of NCI-H1975 human lung adenocarcinoma epithelial cells engineered via CRISPR/Cas9-mediated disruption of the Cyclin T1 (CCNT1) gene. As polyclonal knockout cells, this population contains a spectrum of CCNT1 loss-of-function mutations, providing a robust model to interrogate CCNT1-dependent biology without clonal selection artifacts. This knockout approach disrupts the coding sequence, abolishing functional Cyclin T1 protein expression and enabling dissection of its roles in transcriptional regulation and disease.
The parental NCI-H1975 cell line is a widely utilized model derived from the pleural effusion of a female patient with non-small cell lung adenocarcinoma. These epithelial cells harbor activating mutations in the EGFR and PI3K pathways, among other oncogenic alterations, making them a representative system for studying lung adenocarcinoma biology and therapeutic responses. The line??s well-characterized growth properties, signaling dependencies, and transcriptional profiles render it a suitable host for investigating the consequences of CCNT1 knockout in a clinically relevant cancer context.
Cyclin T1 (CCNT1) forms the positive transcription elongation factor b (P-TEFb) with CDK9, which phosphorylates serine-2 of the RNA polymerase II C-terminal domain (CTD) to drive transcriptional elongation. P-TEFb activity is regulated by reversible association with the inhibitory 7SK snRNP complex (HEXIM1, LARP7, MEPCE, 7SK RNA) and activating factors such as BRD4 and the super elongation complex (SEC, containing AFF1 and ELL2). Signals from NF-??B and other pathways converge on this network, which is hijacked by HIV-1 Tat to promote viral transcription. Key downstream targets include MYC oncogene transcription, HIV-1 LTR-mediated expression, and global elongation programs.
In NCI-H1975 lung adenocarcinoma cells, loss of CCNT1 disrupts P-TEFb function, offering a unique platform to explore transcriptional addiction mechanisms that cancer cells often display. Because these cells exhibit high transcriptional output driven by oncogenes like MYC, CCNT1 knockout can reveal dependencies on sustained elongation for proliferation and survival. Moreover, the model allows assessment of how CDK9 inhibitors influence lung cancer cell viability and transcriptional reprogramming in the absence of the cyclin partner, helping to distinguish CDK9-dependent from CCNT1-specific functions.
This polyclonal knockout cell population is suited for western blotting to assess P-TEFb subunit levels and RNA polymerase II phosphorylation, RT-qPCR and ChIP-qPCR to measure target gene expression and promoter occupancy, and HIV-1 LTR-driven reporter assays for Tat transactivation. Additional applications include RNA-sequencing for transcriptomic profiling, flow cytometry for apoptosis and cell cycle analysis, immunofluorescence to visualize transcriptional complexes, and CDK9 inhibitor sensitivity testing. Researchers can also employ the model for screening novel P-TEFb modulators. For further information, please contact Ascent Research.
