The IDO1 Knockout NCI-H1299 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal population with disrupted IDO1 in the NCI-H1299 human non-small cell lung carcinoma line. This heterogeneous knockout model, generated by CRISPR/Cas9-mediated gene disruption, enables functional studies of IDO1 in a mixed cell pool without clonal isolation.
The NCI-H1299 host cell line originates from a lymph node metastasis of a male lung adenocarcinoma patient. It is p53-deficient with wild-type KRAS and EGFR, representing a genotype common in certain NSCLC subtypes. These epithelial cells are frequently used to study tumor metastasis, drug resistance, and immune interactions, and their p53-null background simplifies the interrogation of p53-independent pathways.
IDO1 (indoleamine 2,3-dioxygenase 1) is a heme-containing enzyme that catalyzes the rate-limiting step of tryptophan degradation into kynurenines, which act as endogenous ligands for the aryl hydrocarbon receptor (AhR). In the tumor microenvironment, IDO1 expression is upregulated by inflammatory cytokines including IFN-??, TNF-??, and TGF-??. Tryptophan depletion activates the stress kinase GCN2, leading to mTOR inhibition and T cell anergy, while kynurenine-AhR signaling promotes differentiation of regulatory T cells and suppresses effector T cell functions. This pathway also influences the expression of immune checkpoint molecules such as PD-1, collectively fostering an immunosuppressive tumor microenvironment.
Within the NCI-H1299 context, IDO1 knockout provides a clean system to study its role in lung cancer immune evasion. Because these cells lack functional p53, potential interactions between IDO1-mediated tryptophan metabolism and p53-dependent stress pathways are minimized, allowing focused investigation of IDO1-specific effects on kynurenine production, AhR activation, and downstream targets like IL-6 and TGF-??. This model is useful for co-culture assays with immune cells to assess changes in T cell proliferation and Treg induction, and for exploring mechanisms of resistance to immunotherapies that block the PD-1 axis.
Typical research applications encompass tumor immunology, development and validation of IDO1 inhibitors, and detailed studies of T cell suppression mechanisms. Researchers can perform kynurenine quantification assays, T cell proliferation and suppression assays, and co-culture experiments with peripheral blood mononuclear cells or purified T cells. Western blotting and RT-qPCR confirm IDO1 disruption and evaluate compensatory changes in pathway components such as AhR and GCN2. Flow cytometry enables profiling of Treg markers and PD-1 expression. The polyclonal knockout population is also well-suited for drug response screening, particularly for IDO1 inhibitors and combination therapies. For further information, please contact Ascent Research.
