The CCNT2 Knockout 786-O Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the human 786-O renal cell carcinoma line. This gene-disrupted pool enables loss-of-function studies of CCNT2, which encodes Cyclin T2, the regulatory subunit of positive transcription elongation factor b (P-TEFb). Unlike monoclonal lines, the polyclonal format provides a heterogeneous knockout population suited for pooled functional assays, reducing clonal bias and enabling robust statistical analysis. The cells are supplied as a ready-to-use product for immediate experimental deployment in cancer biology and transcriptional research.
The 786-O host cell line is a widely used model of VHL-deficient clear cell renal cell carcinoma (ccRCC). It harbors biallelic VHL inactivation, resulting in constitutive stabilization of hypoxia-inducible factor alpha (HIF-??) subunits and a pseudohypoxic transcriptional state. This genetic background drives the expression of genes involved in angiogenesis, metabolism, and proliferation, recapitulating key features of ccRCC. The line is adherent and permissive to standard genetic and pharmacological manipulation, making it an ideal platform for studying oncogenic transcription and tumor suppressor pathways.
Cyclin T2 functions as the regulatory subunit of P-TEFb by dimerizing with CDK9. Under basal conditions, P-TEFb is held inactive by the 7SK snRNP complex (HEXIM1/LARP7) and released upon signals from MYC or NF-??B. Once activated, CCNT2/CDK9 phosphorylates serine 2 of the RNA polymerase II C-terminal domain to promote elongation. CCNT2 directly binds HIV-1 Tat to enhance viral LTR transcription and integrates into the super elongation complex (SEC) via interactions with AFF4 and ELL2 to stimulate immediate early gene expression. Consequently, CCNT2 disruption impairs transcription of proliferation-related and HIV genes.
In the 786-O background where HIF-?? is stabilized, the knockout of CCNT2 enables dissection of P-TEFb-dependent elongation from the broader pseudohypoxic transcriptional program. This model permits direct interrogation of whether ccRCC cells rely on Cyclin T2-mediated CTD phosphorylation for proliferation and survival under VHL-null conditions. By uncoupling elongation from HIF-driven initiation, researchers can identify gene subsets whose expression is elongation-limited and explore synthetic vulnerabilities that may be exploited therapeutically.
This model supports cancer transcription addiction studies, P-TEFb inhibitor validation, and HIV transcription research. Standard assays include western blotting for CCNT2, CDK9, and phospho-RNA Pol II; RNA-seq and ChIP-seq for elongation profiling; cell proliferation and cell cycle analysis by flow cytometry; hypoxia response assays; and xenograft tumor modeling. For more information, contact Ascent Research.
