The HSF1 Knockout 143B Polyclonal Cells comprise a CRISPR/Cas9-edited polyclonal population of human 143B osteosarcoma cells with targeted disruption of the HSF1 gene. This loss-of-function model enables comprehensive investigation of HSF1-dependent stress responses and transcriptional programs in a cancer context. Unlike single-cell clones, the polyclonal population maintains genetic diversity, reducing clonal artifacts and providing a more representative knockout pool for functional assays.
The parental 143B cell line is a well-characterized human osteosarcoma model exhibiting epithelial morphology and a homozygous TP53 mutation. Isolated as a highly tumorigenic derivative of the TE85 cell line, 143B cells are extensively used to study bone cancer biology, metastatic progression, and therapy resistance. The TP53 deficiency disrupts tumor suppressor pathways, sensitizing these cells to proteotoxic stress and making them a particularly relevant host for probing HSF1 function in a compromised genetic background.
HSF1 serves as the master transcriptional regulator of the heat shock response, essential for maintaining proteostasis under stress. Upon exposure to stressors such as elevated temperature, oxidative stress, or heavy metals, HSF1 undergoes trimerization, nuclear translocation, and binding to heat shock elements (HSE) in target gene promoters. It directly upregulates the expression of molecular chaperones including HSP70, HSP90, HSP27, HSP40, and HSP110, as well as co-chaperones like BAG3. HSF1 activity is post-translationally modulated by kinases CK2, AMPK, and MAPK pathway components, and by the deacetylase SIRT1. Key interacting partners such as HSP90, HSBP1, and HSF2, along with modification by SUMO, DAXX, and eEF1A, provide additional regulatory layers that fine-tune HSF1 function, integrating diverse stress signals.
In the context of 143B osteosarcoma, HSF1 supports malignant phenotypes beyond its canonical stress response role. Cancer cells co-opt HSF1 to drive chaperone-mediated proteostasis, which buffers oncogenic stress from genomic instability, misfolded proteins, and altered metabolism. This cytoprotective program promotes tumor cell survival, proliferation, and resistance to chemotherapeutic agents. The 143B TP53-mutant background further heightens reliance on HSF1, since p53 loss impairs alternative stress-resolution mechanisms. Disruption of HSF1 in these cells thus provides a unique model to dissect the dependence of osteosarcoma on heat shock signaling and to evaluate HSF1 as a potential therapeutic target.
Researchers can utilize these HSF1 knockout polyclonal cells to explore heat shock response dynamics in osteosarcoma, screen HSF1 inhibitors, or investigate stress-induced chemoresistance. Representative assays include western blotting for HSP70 and HSP90, RT-qPCR for HSF1 target transcripts, ChIP-qPCR to assess HSF1 binding at HSE sites, and HSE-luciferase reporter assays. Cell viability assays under heat shock or oxidative stress, immunofluorescence for HSF1 nuclear translocation, and flow cytometry for apoptosis under stress conditions are also applicable. The polyclonal knockout format supports robust bulk functional studies while mitigating clonal bias. For further information, please contact Ascent Research.
