The ICOSLG Knockout A-549 Polyclonal Cells constitute a CRISPR/Cas9-edited polyclonal knockout cell population derived from the A-549 human lung adenocarcinoma epithelial cell line, featuring targeted disruption of the ICOSLG gene to create a loss-of-function model. This polyclonal population represents a heterogeneous pool of edited cells, each carrying distinct CRISPR/Cas9-mediated gene disruptions, enabling robust functional studies without clonal selection. The knockout model provides a powerful tool for dissecting ICOSLG-dependent mechanisms in a lung cancer context, specifically within the tumor-immune microenvironment, and is suitable for a wide range of downstream applications requiring ablation of ICOSLG expression.
The A-549 cell line was originally established from the lung adenocarcinoma of a 58-year-old Caucasian male and exhibits hypotriploid chromosomal content with an epithelial morphology. These cells serve as a widely used model for human lung adenocarcinoma, particularly in studies of alveolar type II epithelial cell biology, and retain key features of the respiratory epithelium. The A-549 background is well-characterized for its growth properties, signaling responsiveness, and expression of both epithelial and innate immune markers, making it an ideal host for interrogating the role of immunomodulatory molecules like ICOSLG. The derivative knockout cells maintain the parental line??s core characteristics while eliminating functional ICOSLG expression, offering a clean system for comparative analyses.
ICOSLG (inducible T-cell costimulator ligand, B7-H2) functions as a critical costimulatory ligand that engages the ICOS receptor on activated T cells, thereby enhancing T-cell proliferation, cytokine production, and T follicular helper cell differentiation. Mechanistically, ICOS-ICOSLG binding activates downstream signaling cascades, prominently including the PI3K/Akt and NF-kB pathways, with involvement of adaptor proteins such as TRAF2 and TRAF6. ICOSLG expression is regulated by upstream pro-inflammatory stimuli including TNF-alpha, IL-1beta, IFN-gamma, LPS, and CD40 ligation, often via NF-kB transcription factors. Downstream targets encompass PI3K, Akt, NFAT, and a spectrum of cytokines (IL-4, IL-10, IL-17, IFN-gamma) central to adaptive immunity. While ICOS is its dominant receptor, weak interactions with CD28 and CTLA-4 have also been reported, underscoring its nuanced role in immune checkpoint biology.
In the context of lung adenocarcinoma, ICOSLG is increasingly recognized for its role in shaping the tumor-immune microenvironment, contributing to immune evasion and modulating T-cell responses within the tumor milieu. A-549 cells express ICOSLG under basal conditions and upregulate it in response to inflammatory cues, mimicking features of in vivo lung tumors. The ICOSLG knockout A-549 model thus enables precise dissection of epithelial-cell-intrinsic contributions to immune regulation, tumor progression, and therapeutic resistance. Researchers can employ this system to evaluate how loss of ICOSLG alters cytokine networks, T-cell activation profiles, and signaling crosstalk, providing insights into potential combination strategies targeting the ICOS/ICOSLG axis in lung cancer.
This polyclonal knockout product is suited for diverse experimental workflows, including western blotting and RT-qPCR for expression quantification, flow cytometry for surface ICOSLG analysis, and functional co-culture assays with T cells coupled to cytokine readouts (ELISA/ELISpot). It further supports high-content applications such as RNA-seq, ChIP-qPCR for NF-kB binding, immunofluorescence, and phenotypic assays examining proliferation, migration, invasion, and apoptosis. The model is particularly valuable for drug screening of ICOSLG inhibitors, investigation of T follicular helper cell differentiation in a tumor setting, and mechanistic studies of PI3K/Akt/NF-kB signaling. For further details, please contact Ascent Research.
