The IGFBP5 Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal cell population in which the insulin-like growth factor binding protein 5 (IGFBP5) gene has been disrupted. This loss-of-function model provides a heterogeneous pool of cells lacking functional IGFBP5, enabling comprehensive study of its biological roles without clonal isolation. The cells retain the near-haploid characteristics of the HAP1 parental line, allowing direct genotype-phenotype correlation in a pooled format.
HAP1 cells originate from a male patient with BCR-ABL-positive chronic myelogenous leukemia (CML) and possess a near-haploid karyotype, except for a disomic fragment of chromosome 15. This haploid state makes them an established platform for genetic screening and functional genomics, offering a simplified background where each edited allele manifests its phenotype without confounding by a second allele. The BCR-ABL oncogenic context remains relevant for studying signaling networks intersecting with IGF pathways.
IGFBP5 functions as a critical modulator of IGF bioavailability by binding IGF1 and IGF2, thereby controlling their interaction with IGF1R. Upon knockout, the loss of IGF sequestration enhances IGF1R-mediated activation of PI3K-AKT (through IRS1, PI3K, AKT, mTOR) and MAPK (via RAF, MEK, ERK) cascades. IGFBP5 also interacts with integrins ITGAV/ITGB3 and extracellular matrix proteins, influencing adhesion and migration; its absence disrupts these interactions. Furthermore, knockout attenuates TGF-beta/SMAD2/3 and p53-mediated induction of CDKN1A, impairing growth inhibition and cellular senescence. Upstream regulators such as TGFB1, TP53, retinoic acid, and glucocorticoids normally induce IGFBP5 expression, but in this system these regulatory inputs are decoupled from downstream effectors, permitting dissection of IGF-dependent and -independent functions.
In the HAP1 background, IGFBP5 deletion likely synergizes with constitutive BCR-ABL kinase activity, intensifying proliferative and survival signals. The haploid state ensures that every disruption event directly contributes to the observed phenotype, increasing sensitivity for detecting subtle modulations that may be masked in diploid cells. This makes the model particularly valuable for exploring cross-talk between integrin-mediated adhesion, IGF signaling, and CML-driven oncogenesis.
Typical applications include western blotting and RT-qPCR to assess targets such as phosphorylated AKT, ERK1/2, and CDKN1A; proliferation and colony formation assays; apoptosis analysis by Annexin V staining; senescence-associated beta-galactosidase assays; and migration studies. The polyclonal pool is also suited for IGF pathway inhibitor screening and high-throughput drug sensitivity profiling in a CML-relevant haploid system. For further technical information, please contact Ascent Research.
