The ID3 Knockout MCF-7 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal cell population derived from the MCF-7 cell line, with targeted disruption of the ID3 gene. This heterogeneous knockout pool enables loss-of-function studies without the constraints of clonal selection, maintaining population diversity for bulk culture assays. The polyclonal format is particularly suited for investigating ID3-dependent phenotypes in a well-characterized estrogen receptor-positive breast cancer context.
MCF-7 is a human mammary epithelial adenocarcinoma cell line established from the pleural effusion of a 69-year-old female with metastatic disease. It is estrogen receptor-positive (ER+), progesterone receptor-positive (PR+), and HER2-negative (HER2-), representing the luminal A molecular subtype. Widely used for hormone signaling and proliferation studies, MCF-7 provides an ideal platform to dissect ID3 function in estrogen-responsive breast cancer biology.
ID3 functions as a dominant-negative inhibitor of basic helix-loop-helix (bHLH) transcription factors, including TCF3 (E2A), TCF4, MYOD1, TAL1, and HEB. It forms non-functional heterodimers that impede binding to E-box DNA sequences, effectively repressing bHLH-mediated transcription. ID3 expression is governed by upstream cues such as TGF-beta, EGF, BMP2, Notch ligands, and estrogen receptor alpha, as well as transcriptional regulators E2F1 and MYC. Its downstream influence extends to critical targets: CDKN1A (p21) and CCND1 (cyclin D1) regulate cell cycle progression, while CDH2 (N-cadherin), SNAI1 (Snail), and VIM (vimentin) modulate epithelial-mesenchymal transition (EMT). Within the TGF-beta pathway, SMAD2/3/4 complexes interact with TCF3 to control ID3 expression, establishing feedback that balances proliferation and differentiation.
In MCF-7 cells, ID3 integrates signals from Notch, TGF-beta, and Wnt pathways to promote proliferation and EMT. Knockout of ID3 disrupts these oncogenic processes, allowing dissection of hormone-dependent and -independent growth, invasion, and drug sensitivity. This model is instrumental for studying how ID3 loss impacts luminal breast cancer progression and metastasis.
This knockout model enables functional analysis of ID3 in breast cancer, including proliferation assays (MTT), migration/invasion studies (Boyden chamber), apoptosis measurement (Annexin V), drug sensitivity screening, and EMT evaluation. Researchers can validate knockout effects via Western blotting for ID3 and downstream proteins, RT-qPCR for transcript levels, immunofluorescence for localization, and flow cytometry for cell cycle profiling. Reporter assays quantify E-box activity, co-immunoprecipitation confirms ID3-bHLH interactions, and RNA-seq captures global transcriptomic changes. For additional information, please contact Ascent Research.
