The H2AX Knockout CAL-27 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal cell population featuring a targeted disruption of the H2AX gene in the CAL-27 host cell line. This loss-of-function model is engineered to eliminate H2AX expression, providing a robust tool for investigating DNA damage response and repair mechanisms. The polyclonal format ensures a heterogeneous genetic background that captures a realistic range of cellular responses.
The CAL-27 cell line was originally derived from a human tongue squamous cell carcinoma, representing a widely utilized model for oral squamous cell carcinoma (OSCC). This adherent epithelial line exhibits characteristic features of OSCC, including aggressive growth and genomic instability, making it highly relevant for studies focused on head and neck cancer biology. The CAL-27 background is particularly suited to dissecting the interplay between oncogenic transformation and DNA repair pathways.
H2AX encodes a histone H2A variant that serves as a critical sensor of DNA double-strand breaks (DSBs). Upon DSB induction by ionizing radiation or radiomimetic agents, H2AX is rapidly phosphorylated at Ser139 by upstream kinases ATM, ATR, and DNA-PKcs to form ??H2AX. This modification creates a chromatin platform that recruits and retains downstream factors including MDC1, 53BP1, and the BRCA1?CNBS1?CRAD50?CMRE11 complex, thereby orchestrating non-homologous end joining and homologous recombination repair. H2AX also participates in ATM/ATR-mediated checkpoint signaling, ultimately influencing p53-dependent cellular outcomes. Disruption of H2AX abolishes this damage-induced amplification cascade, leading to defective DSB repair, sustained DNA damage, and elevated genomic instability.
In the oral squamous cell carcinoma context, genomic instability is a hallmark, and the DNA damage response is often compromised yet remains a targetable vulnerability. The H2AX knockout in CAL-27 cells permits a detailed examination of how loss of this key histone variant exacerbates radiosensitivity and chemosensitivity, and how it may influence tumor progression, metastasis, and therapy resistance. This model is particularly valuable for delineating DDR dependencies in OSCC and for testing synthetic lethal strategies or radiosensitization approaches.
Typical experimental applications encompass DNA damage signaling and repair kinetics assays using immunofluorescence for ??H2AX foci or western blotting, comet assays for DNA break quantification, clonogenic survival assays post-irradiation or chemotherapeutic treatment, flow cytometry for cell cycle distribution and apoptosis, RT-qPCR arrays for DDR transcript profiling, RNA-seq for global expression changes, and drug sensitivity screens. This product supports studies in biomarker discovery, genomic instability syndromes, and cancer therapeutic development. For additional product information or technical support, please contact Ascent Research.
