The BRD3 Knockout HCT 116 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal population derived from the HCT 116 human colorectal carcinoma cell line, designed to disrupt the coding sequence of the BRD3 gene. This knockout model provides a powerful tool for loss-of-function studies examining the role of the bromodomain-containing protein 3 (BRD3) in oncogenic transcriptional programs. The polyclonal nature of the cell population ensures representation of diverse editing events, enabling robust functional interrogation without overstating clonal uniformity. Researchers can use these cells to dissect BRD3-dependent mechanisms in a genetically defined epithelial tumor background.
The parental HCT 116 cell line is a widely used epithelial model of colorectal carcinoma, characterized by hallmark mutations in KRAS (G13D), CTNNB1, and PIK3CA (H1047R). These alterations create a constitutively active signaling environment that drives proliferation and survival, making it an ideal context to investigate how BRD3-mediated transcriptional elongation contributes to tumorigenicity. The cells maintain their adherent morphology and are suitable for standard culture conditions, facilitating integration into existing experimental workflows aimed at understanding colorectal cancer biology and therapeutic responses.
BRD3 functions as a reader of acetylated histones, primarily at promoters and enhancers marked by H3K27ac and H4K5ac, where it recruits the P-TEFb complex (CDK9/Cyclin T1) to release paused RNA polymerase II and promote transcriptional elongation. Through this mechanism, BRD3 directly regulates the expression of key oncogenes such as MYC, CCND1, CDK6, and BCL2. Upstream signaling from histone acetyltransferases like CBP/p300 establishes the acetylated chromatin landscape recognized by BRD3, while pharmacological BET bromodomain inhibitors (e.g., JQ1, I-BET762) competitively displace BRD3 from chromatin. BRD3 operates within a network that includes the Mediator complex and closely related family members BRD2 and BRD4, which can exhibit partial functional redundancy.
In HCT 116 cells, BRD3-driven transcription is particularly relevant due to the constitutive activation of WNT/??-catenin and PI3K pathways, which converge on MYC and cell cycle regulators. The CTNNB1 mutation stabilizes ??-catenin, leading to elevated MYC expression, a process further amplified by BRD3-mediated elongation. Concurrently, the PIK3CA H1047R mutant enhances growth signaling, creating a dependency on BRD3 for sustained proliferation. This cell model thus enables dissection of how BRD3 integrates oncogenic inputs to maintain the malignant phenotype, and it serves as a platform to study intrinsic or acquired resistance to BET inhibitors in the context of multiple driver mutations.
Typical applications include mechanistic studies of BRD3 in colorectal cancer oncogene regulation, functional characterization of BRD3 in cell cycle progression and apoptosis, and drug-sensitivity profiling to evaluate combinatorial therapies targeting BET proteins and parallel pathways. Representative assays range from Western blotting for BRD3, MYC, and phospho-RB, to RT-qPCR analysis of MYC, CCND1, and CDK6, as well as chromatin immunoprecipitation to assess BRD3 and histone acetylation occupancy at target genes. Proliferation (MTT/BrdU) and apoptosis (Annexin V/PI) assays, along with RNA-seq for transcriptome-wide effects, are routinely employed. This product is intended for laboratory research use only; for further technical details, please contact Ascent Research.
