The ISG15 Knockout NCI-H1975 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the NCI-H1975 human lung adenocarcinoma line. The product features targeted disruption of ISG15, eliminating expression of the ubiquitin-like protein and its associated ISGylation and cytokine activities. As a polyclonal pool, it offers a robust loss-of-function model without single-cell cloning, retaining the parental line??s EGFR-mutant background for studies linking ISG15 to oncogenic signaling and drug sensitivity.
NCI-H1975 is a non-small cell lung cancer (NSCLC) line from a female non-smoker??s pleural effusion, harboring EGFR L858R and T790M mutations. These mutations confer sensitivity to first-generation TKIs and subsequent resistance, with T790M enabling response to osimertinib. The line is a cornerstone for investigating EGFR-driven tumor biology, TKI resistance, and metastasis in lung adenocarcinoma.
ISG15 is strongly induced by type I (IFN-??/??) and type II (IFN-??) interferons via JAK-STAT signaling. Upon activation, STAT1, STAT2, and IRF9 form the ISGF3 complex that drives ISG15 transcription. IRF3 and IRF7, activated by viral nucleic acids or LPS, also contribute. The ISG15 protein functions intracellularly by conjugating to targets through UBA7, UBE2L6, and HERC5 (ISGylation), a process reversed by USP18. Extracellularly, ISG15 acts as a cytokine via the ITGAL receptor. ISGylation modulates stability and activity of STAT1, JAK1, ERK1/2, and p53, thereby influencing antiviral immunity, NF-??B signaling, and tumor pathways.
In NCI-H1975 cells, ISG15 disruption abolishes ISGylation and extracellular cytokine function, impairing interferon responses and potentially rewiring EGFR downstream signaling. The knockout may sensitize cells to osimertinib by attenuating ISG15-dependent pro-survival mediators such as ERK1/2 and STAT1, providing a model to study the intersection of innate immunity and targeted therapy resistance.
Researchers can use these cells for Western blot detection of ISG15 and ISGylation, RT-qPCR of ISGs, flow cytometry for ITGAL, and co-immunoprecipitation of conjugates. Functional assays include viability (MTT/PrestoBlue), migration, invasion, and drug sensitivity testing with EGFR TKIs. RNA-seq under interferon stimulation reveals ISG15-dependent transcriptomes. For in vivo xenograft studies, the cells allow assessment of tumor growth and therapy response. For additional inquiries, please contact Ascent Research.
