The ISG15 Knockout CAL-27 Polyclonal Cells product comprises a heterogeneous population of CAL-27 cells engineered via CRISPR/Cas9-mediated disruption of the ISG15 gene. This polyclonal knockout pool provides a mixed genetic background that facilitates robust loss-of-function analyses without clonal selection bias. Researchers can immediately employ this model to investigate ISG15-dependent cellular functions upon appropriate culture and stimulation.
The host cell line CAL-27 is a well-characterized human oral squamous cell carcinoma line originally derived from a 56-year-old male patient. This adherent epithelial cell line serves as a standard model for studying oral cancer biology, including tumour proliferation, invasion, and therapeutic response. Its genetic background retains key features of tongue squamous cell carcinoma, making it relevant for translational research in head and neck oncology.
ISG15 encodes a 15-kDa ubiquitin-like protein that is strongly induced by type I interferons (IFN-alpha/beta) and, to a lesser extent, by IFN-gamma. Induction occurs through the canonical JAK-STAT pathway: binding of interferons to IFNAR1/IFNAR2 activates JAK1 and TYK2, which phosphorylate STAT1 and STAT2. These factors assemble with IRF9 to form ISGF3, translocate to the nucleus, and bind interferon-stimulated response elements (ISRE) in the ISG15 promoter. Additional upstream regulators such as IRF3, IRF7, and NF-??B can also contribute, particularly during viral infection or TLR agonist stimulation. Following translation, ISG15 becomes conjugated to target proteins through a three-step enzymatic cascade involving the E1-activating enzyme UBE1L, the E2-conjugating enzyme UbcH8, and E3 ligases including HERC5 and TRIM25. This ISGylation modifies critical substrates like STAT1, JAK1, ERK, and p53, altering their stability, localization, and activity. Concurrently, USP18 functions as a deISGylating enzyme that removes ISG15 from modified proteins. Besides its conjugation role, ISG15 can be secreted as a free cytokine that stimulates NK cell activity and modulates innate immune responses.
Genetic disruption of ISG15 in CAL-27 cells creates a powerful tool to dissect its dual roles in antiviral immunity and tumour biology. In the context of oral squamous cell carcinoma, ISG15 knockout is expected to impair interferon-mediated antiviral responses and may attenuate proliferative or pro-survival signals driven by ISGylation. This model enables dissection of how ISG15-dependent modifications influence oncogenic pathways, such as those involving ERK and p53, and allows assessment of the interplay between innate immunity and tumour progression in oral epithelial cells.
This polyclonal knockout product is suited for a range of functional assays, including interferon stimulation coupled with RT-qPCR or RNA-seq to profile ISG expression, Western blotting to monitor ISG15 and ISGylation levels, co-immunoprecipitation to map ISG15 targets, and viral infection experiments to evaluate antiviral competence. Additional applications encompass cell proliferation, apoptosis, and migration/invasion assays, as well as flow cytometry-based immune profiling. Researchers can use this model to screen for ISG15-dependent signalling nodes in oral cancer or to explore cancer immunotherapy strategies. For technical inquiries or ordering assistance, please contact Ascent Research.
