The IGFBP5 Knockout 143B Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the human osteosarcoma cell line 143B. This product provides a genetically heterogeneous pool of cells harboring targeted disruptions in the IGFBP5 gene, enabling robust loss-of-function studies across a range of downstream signaling and phenotypic assays. The polyclonal format avoids clonal selection artifacts and reflects population-level gene disruption, making it suitable for experiments that prioritize functional knockout over clonal homogeneity.
The 143B cell line is a well-characterized human osteosarcoma model originally established from a primary bone tumor. These cells exhibit osteoblastic features, including expression of alkaline phosphatase and the capacity for matrix mineralization, and retain key oncogenic signaling pathways such as constitutive PI3K/AKT and MAPK/ERK activation. Their aggressive phenotype in vitro and in vivo, along with a defined p53 mutation background, makes them a valuable platform for investigating bone cancer biology and tumor-stroma interactions.
IGFBP5 encodes insulin-like growth factor-binding protein 5, a secreted protein that binds IGF-1 and IGF-2 with high affinity and modulates their bioavailability in the extracellular environment. In parallel, IGFBP5 can exert IGF-independent functions through interactions with thrombospondin-1, integrin ??V??3, and plasminogen, influencing cell adhesion, migration, and survival. Transcription of IGFBP5 is regulated by multiple upstream factors, including p53, Sp1, TGF-??, retinoic acid, parathyroid hormone (PTH), and estrogen, placing it at a critical node integrating diverse cellular inputs. Downstream, IGFBP5 controls the availability of IGF ligands to the IGF-1 receptor (IGF-1R), thereby tuning the activity of the PI3K/AKT and RAS/RAF/MEK/ERK signaling cascades, which govern proliferation, survival, and metabolic responses. Additionally, IGFBP5 influences the expression of Bcl-2 and caspase activation pathways, further connecting it to apoptotic control. Its involvement in bone remodeling is underscored by its regulation of IGF bioavailability in the osteoblast niche and cross-talk with TGF-?? and Wnt/??-catenin pathways.
In the osteosarcoma setting, disruption of IGFBP5 is expected to enhance local IGF-1 and IGF-2 bioavailability, leading to amplified signaling through IGF-1R, IRS-1, PI3K, AKT, and mTOR on the one hand, and via RAS, RAF, MEK, and ERK1/2 on the other. This hyperactivation can promote proliferation and survival of 143B cells, while loss of IGF-independent functions may concurrently affect apoptosis sensitivity and cell adhesion properties. The resulting phenotype may help dissect the dual roles of IGFBP5 as both a suppressor and promoter of tumorigenesis depending on context. Furthermore, because 143B cells harbor a mutant p53 background, this model allows exploration of p53-independent regulation of IGFBP5 and its contribution to osteosarcoma aggressiveness, metastasis, and response to therapeutics targeting the IGF axis.
This polyclonal knockout model is ideally suited for a wide range of investigations in cancer biology and signal transduction. Typical applications include analyzing AKT and ERK phosphorylation by western blotting, quantifying downstream target gene expression by RT-qPCR, and assessing cell proliferation via MTT assays. The product facilitates detailed apoptosis studies using Annexin V staining, as well as migration and invasion assays in Transwell chambers. Co-immunoprecipitation can be used to examine the interaction between IGF-1 and residual IGFBPs, while phospho-signaling arrays enable broader profiling of pathway alterations. Beyond osteosarcoma, these cells are valuable tools for studying IGFBP5 function in breast cancer, prostate cancer, osteoporosis, and pulmonary fibrosis. The polyclonal population is particularly advantageous for high-throughput drug screening campaigns that require a representative knockout genotype without clonal bias. For additional information, please contact Ascent Research.
