Preclinical evidence of progesterone as a new pharmacological strategy in human adrenocortical carcinoma cell lines

Background: and Purpose: Adrenocortical cancer (ACC) is a rare malignant neoplasm with a dismal prognosis. The treatment includes mitotane and EDP chemotherapy (etoposide, doxorubicin, cisplatin). However, new therapeutic approaches for advanced ACC are needed, particularly targeting the metastatic process. Here, we deepen the role of progesterone as a new potential drug useful in ACC, in line with other studies that demonstrated its antitumoral effect in other cancers. Experimental Approach: NCI-H295R, MUC-1, and TVBF-7 ACC cell lines were used. Cell apoptosis and cell cycle were analyzed by flow cytometry. Cell migration and invasiveness were studied using transwell assays, and metalloprotease 2 activity by zymography. Cell xenografts in zebrafish embryos were performed by measuring both the tumor areas and the number of embryos with metastasis. Key Results: Progesterone exerted a long-lasting cytotoxic effect in metastatic cell lines, MUC-1 and TVBF-7. Progesterone caused apoptosis in NCI-H295R and MUC-1 cells, inducing changes in the cell cycle distribution, while autophagy was predominantly activated in TVBF-7 cells. In the zebrafish embryos, progesterone significantly reduced each ACC cell line’s xenograft tumor area and metastasis formation in embryos injected with metastatic cells. These results were confirmed in vitro, where the reduction of invasion was mediated, at least in part, by the decrease in MMP2 levels. Conclusion and Implications: Our results give support to the role of progesterone in ACC. The involvement of its analogous (megestrol acetate) in reducing ACC progression in ACC patients undergoing EDP-M therapy is now under investigation in the PESETA phase II clinical study.