The beneficial androgenic action of steroidal aromatase inactivators in estrogen-dependent breast cancer after failure of nonsteroidal drugs

• Published in: Cell death & disease Vol. 10; no. 7; pp. 494 - 14
• Main Authors: Gao, Lanyang, Bao, Zheng, Deng, Heng, Li, Xiaofang, Li, Jiamin, Rong, Zuyuan, Yang, Youzhe, Liu, Ling, Nie, Dan, Wang, Guilin, Teichmann, Alexander T., Wieland, F. Heinrich
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.06.2019; Springer Nature B.V
• Subjects: 13; 13/1; 13/109; 13/31; 38; 38/77; 59; 59/36; 59/5; 631/67/1347; 631/80/641/2358; 692/699/67/1347; Androgens; Androgens - metabolism; Androstenedione - analogs & derivatives; Androstenedione - pharmacology; Androstenedione - therapeutic use; Animals; Anthracenes - toxicity; Antiandrogens; Antibodies; Antitumor activity; Aromatase; Aromatase - genetics; Aromatase - metabolism; Aromatase Inhibitors - pharmacology; Biochemistry; Biomedical and Life Sciences; Breast cancer; Breast Neoplasms - chemically induced; Breast Neoplasms - metabolism; Cell Biology; Cell Culture; Cell cycle; Cell Cycle - drug effects; Cell Line, Tumor; Cell proliferation; Cell Proliferation - drug effects; Cross-resistance; Cyclin D1; Cytometry; Estrogen receptors; Estrogens; Female; Humans; Immunology; Inactivators; Life Sciences; Male; Mammary Neoplasms, Animal - chemically induced; Mammary Neoplasms, Animal - metabolism; MCF-7 Cells; Metabolites; Piperidines - toxicity; Prostate - drug effects; Prostate - metabolism; Protein Binding; Rats; Reporter gene; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; Seminal Vesicles - drug effects; Seminal Vesicles - metabolism; siRNA; Steroids - pharmacology; Steroids - therapeutic use; Sterols; Tumors
• ISSN: 2041-4889; 2041-4889
• DOI: 10.1038/s41419-019-1724-9

Direct treatment of ER (+) breast cancer with Formestane diminishes the tumor within weeks. This is unlikely due to lack of estrogens alone. We proposed that it is the negative influence of androgens on the growth of ER(+) breast cancer. We investigated the influence of Formestane and Exemestane and of their major androgenic metabolites 4-hydroxytestosterone and 17-hydroexemestane on the proliferation of MCF-7 cells and ZR-75-1 cells. Inhibitory effects could be prevented by antiandrogens and siRNA. Activation of the AR in MCF-7 and U2-OS cells was tested by reporter gene assays. In vivo androgenicity was evaluated using the Hershberger assay. Influence on the cell cycle was demonstrated by flow-cytometry. Influence of androgens on the activity of CCND1 was demonstrated by Chip-qPCR. Antitumor activity was determined by topical treatment of DMBA tumors. We found that breast cancer cells can metabolize Formestane and Exemestane to androgenic compounds which inhibit proliferation. This can be explained by hindering the accessibility of CCND1 by histone modification. Androgenic metabolites can abolish the growth of DMBA-tumors and prevent the appearance of new tumors. The lack of cross-resistance between steroidal and nonsteroidal aromatase inhibitors is due to inhibitory effects of androgenic steroidal metabolites on the production of cyclin D1. These sterols not only inhibit proliferation of cancer cells but can also stop the growth of DMBA cancers upon direct absorption into the tumor. The quick and considerable effect on ER(+) tumors may open a new avenue for neodjuvant treatment.