AhR Reporter HCT116 Cells

Cell line description

HCT116-Lucia™ AhR cells were generated from the human colorectal carcinoma HCT116 cell line, which endogenously expresses the aryl hydrocarbon receptor (AhR) [1]. Their colorectal origin makes these cells particularly relevant for studying AhR responses to intestinal and microbiota-derived ligands.

HCT116-Lucia™ AhR cells stably express the secreted Lucia® luciferase reporter gene under the control of a minimal promoter coupled to the complete regulatory sequence of the human CYP1A1 gene, containing six dioxin response elements (DREs).

In the absence of a ligand, AhR is retained in the cytoplasm as part of a multiprotein complex. Upon binding of an AhR agonist, such as FICZ, AhR is activated and released from its cytoplasmic complex. Activated AhR then translocates into the nucleus, where it heterodimerizes with the AhR nuclear translocator (ARNT). The AhR/ARNT complex binds to DREs and induces the transcription of AhR-responsive genes. In HCT116-Lucia™ AhR cells, activation of this pathway also drives the expression and secretion of Lucia® luciferase. AhR activation can therefore be readily quantified by measuring Lucia® luciferase activity in the cell culture supernatant using QUANTI-Luc™ 4 Lucia/Gaussia.

AhR Background

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcriptional factor widely expressed in barrier tissues [2]. AhR plays a key role in gut-microbiota and host immune homeostasis [2]. Besides xenobiotics, including the prototypic AhR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a variety of dietary-derived AhR ligands have been identified, many of which are byproducts of tryptophan metabolism [2].

Inactive AhR resides inactive in the cytoplasm within protein complex consisting of Hsp90:XAP2:p23:Src. The AhR canonical genomic signaling pathway occurs as follows: upon ligand binding, the complex undergoes conformational changes and partly translocates into the nucleus. AhR heterodimerizes with AhR nuclear translocator (ARNT) before binding to dioxin response elements (DREs) in the upstream regulatory regions of AhR target genes, such as the cytochrome P450-dependent monooxygenase Cyp1a1 or the AhR repressor (AhRR) [2].

Given the pleiotropic and highly context-dependent nature of AHR signaling, further studies are essential to fully elucidate its complex biological functions and therapeutic potential across a broad range of diseases, including cancer, inflammatory and autoimmune disorders [1-2]. For example, disruptions in AhR signaling have been shown to be involved in the development of diseases such as inflammatory bowel disease (IBD) and atopic dermatitis (AD) [2].

References

1. Karasová M, et al., 2022. Inhibition of Aryl Hydrocarbon Receptor (AhR) Expression Disrupts Cell Proliferation and Alters Energy Metabolism and Fatty Acid Synthesis in Colon Cancer Cells. Cancers (Basel). 14(17):4245
2. Coumoul X, et al., 2026. The aryl hydrocarbon receptor: structure, signaling, physiology and pathology. Signal Transduct Target Ther.11(1):20.