AhR molecular pathway in adrenal carcinoma cell: crosstalk, modulators and their evaluation for pharmacological purposes

Adrenocortical carcinoma (ACC) is a rare, aggressive and lethal endocrine neoplasm. Mitotane is the only drug approved as a treatment, although it has a narrow therapeutic range, poor bioavailability and several side effects. This chemotherapy drug is a derivative of the well-known insecticide DDT. Human exposure to persistent organic pollutants, such as DDT, is of great concern due to a variety of adverse effects resulting from prolonged exposure and bioaccumulation. The transcription factor AhR has been defined as an essential environmental sensor and can act as a positive or negative regulator of carcinogenesis. The AhR pathway plays a major role in the detoxification of xenobiotics. In this study we will also evaluate its possible involvement in ACC. Furthermore, we have evaluated how AhR modulation can be used in the future to develop new therapies in ACC. To do this, we used an ACC H295R cell model expressing the Firefly luciferase protein under the control of AhR-responsive elements. In the first part of this study, we characterized the tool at the molecular level by evaluating its ability to respond to different stimuli mediated by known AhR modulators. In the second part, we sought to investigate the peculiarities of each AhR modulator in our ACC cell model, trying to identify whether this pathway is important for the development/sustainability of ACC or as a possible target for future anticancer therapies. Of note, hypoxia is one of the well-known hallmarks of cancer and the main inducible factor regulating this process, the HIF-1α protein, shares the ARNT/HIF-1β cofactor with AhR. On this basis, to try to understand the fine tuning and crosstalk of these two molecular pathways in ACC, we used a similar approach to the previous one to create a cell model expressing the enzymatic marker NanoLuc® under the control of HIF-responsive elements. Using our ACC cellular tools, we identified a complex modulation of AhR pathways that could indicate the involvement of AhR, alone or associated with other molecular players, in the response to different active substances. With our study, we underline how in vitro experiments are a powerful tool, which broadens the knowledge of molecular mechanisms, which allows the identification of new molecular pathways with future pharmacological implications.