The CCNT2 Knockout NCI-H1299 Polyclonal Cells constitute a CRISPR/Cas9-edited polyclonal knockout cell population generated from the NCI-H1299 human non-small cell lung carcinoma (NSCLC) cell line. This loss-of-function model is designed to disrupt the CCNT2 gene, which encodes Cyclin T2, a critical regulatory subunit of the positive transcription elongation factor b (P-TEFb). By targeting CCNT2 with CRISPR/Cas9, the resultant heterogeneous population of knockout cells enables robust assessment of Cyclin T2-dependent biological processes without the requirement for clonal isolation. The polyclonal format preserves the genetic diversity inherent to the parental line, thereby reducing clonal artifacts and better reflecting population-level responses in functional experiments.
The parental NCI-H1299 cell line was originally isolated from a lymph node metastasis of a lung adenocarcinoma and is a well-established model for NSCLC research. These epithelial cells exhibit a homozygous deletion of the TP53 tumor suppressor gene, coupled with wild-type KRAS and EGFR alleles, a genotype that mirrors certain clinical subsets of lung cancer. The TP53-null status abrogates p53-mediated cell cycle checkpoints and apoptotic programs, facilitating studies into p53-independent signaling pathways and oncogenic drivers. Consequently, NCI-H1299 cells are extensively utilized to investigate tumorigenesis, metastatic dissemination, and resistance to therapeutic agents, providing a physiologically relevant context for gene knockout studies.
Cyclin T2 partners with CDK9 to form the active P-TEFb heterodimer, which phosphorylates serine 2 of the RNA Polymerase II CTD and negative elongation factors DSIF and NELF complex, thereby releasing paused Pol II into productive elongation. P-TEFb is regulated by reversible sequestration in the 7SK snRNP complex containing HEXIM1 and LARP7; upstream signals from MYC, NF-??B, and EGF promote its release. Promoter recruitment involves interactions with BRD4 and super elongation complex components AFF4 and ELL. Crucially, HIV-1 Tat hijacks Cyclin T2/CDK9, tethering P-TEFb to the viral LTR to drive viral transcriptional transactivation.
In NSCLC, aberrant P-TEFb activity fuels oncogene expression and malignant phenotypes. The CCNT2 knockout in NCI-H1299 cells enables specific dissection of Cyclin T2??s role in proliferation, survival, and transcriptional reprogramming under TP53-null conditions. It facilitates studies on how MYC and NF-??B signals converge on P-TEFb, and provides a platform for CDK9 inhibitor validation by revealing Cyclin T2-dependent vulnerabilities. The model also aids in distinguishing functions of Cyclin T1 versus T2 in CDK9-mediated transcription.
This polyclonal knockout population supports Western blotting for Cyclin T2 and phospho-Pol II Ser2, RT-qPCR, RNA-seq, and ChIP-qPCR for Pol II occupancy. Functional assays include MTT proliferation, apoptosis, and CDK9 inhibitor sensitivity testing. These methods allow comprehensive analysis of transcriptional elongation dynamics and Cyclin T2-dependent cellular phenotypes. The cells also serve for HIV-1 Tat-dependent transcription studies. For further information, please contact Ascent Research.
