The ID3 Knockout T-47D Polyclonal Cells are a CRISPR/Cas9-edited polyclonal cell population derived from the T-47D human breast adenocarcinoma line, with targeted disruption of the ID3 gene. This model enables functional studies of ID3, a dominant-negative inhibitor of bHLH transcription factors, in an ER-positive, PR-positive, HER2-negative cellular context. The polyclonal pool maintains genetic diversity, providing a robust system for loss-of-function experiments without clonal selection artifacts.
T?47D cells originate from a pleural effusion of invasive ductal carcinoma and are characterized by estrogen and progesterone receptor positivity with absence of HER2 amplification. They serve as a well-established model for luminal A breast cancer, extensively used in studies of hormone signaling, endocrine resistance, and tumor progression. Their adherent growth and documented genomic profile make them amenable to CRISPR genome editing and downstream phenotypic analyses.
ID3 encodes a dominant?negative HLH protein that heterodimerizes with E?proteins (TCF3/TCF12), blocking their DNA binding and transcriptional activity. It is transcriptionally induced by TGF??? and BMP signals via receptor?activated SMAD complexes (SMAD2/3 and SMAD1/5/8), and further regulated by EGF, p53, and hypoxia. ID3 suppresses cyclin?dependent kinase inhibitors CDKN1A (p21) and CDKN1B (p27) while promoting CCND1 (cyclin D1) expression, thereby accelerating G1??S transition. It also modulates VEGFA and MYC pathways, linking it to angiogenesis and metabolism. Interactions with MYOD1, ELK1, and the inhibitors ID1/ID2 position ID3 at the intersection of differentiation and proliferation control.
In T?47D cells, ID3 knockout offers a platform to dissect crosstalk between ER signaling and bHLH networks, potentially impacting responses to endocrine therapies. The model is invaluable for studying epithelial?mesenchymal transition (EMT), as ID3 restrains invasiveness and maintains epithelial traits. Consequently, ID3?null T?47D cells can be used to analyze migration, invasion, and metastasis, and to screen compounds that target these processes.
Applications include western blotting and RT?qPCR for ID3 and target validation, proliferation assays (MTT, BrdU), flow cytometry for cell cycle and apoptosis, transwell migration/invasion, and reporter assays for bHLH activity. Transcriptomic analyses (RNA?seq) and xenograft tumor models extend investigations to global gene expression and in vivo tumorigenicity. This polyclonal knockout pool is a versatile resource for breast cancer research and drug screening. For further information, please contact Ascent Research.
