Fluoxymesterone is a synthetic androgen drug that decomposes slowly in the body and has a long-lasting effect[1]. Fluoxymesterone promotes protein anabolism and inhibits amino acid catabolism by activating androgen receptors, and can competitively inhibit estrogen receptors, thereby inhibiting the growth of hormone-dependent tumors[2]. Fluoxymesterone is commonly applied in research areas such as hypogonadism, delayed puberty, and advanced breast cancer[3,4].
In vitro, treatment of human colon cancer SW-620 cells with Fluoxymesterone (1-10000nM) for 2h concentration-dependently inhibited the activity of 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), with an IC50 value of 160 ± 10nM[5]. Treatment of primary osteoblasts from neonatal mouse calvaria cultured in serum-free DMEM with Fluoxymesterone (1nM) for 24h ([3H]thymidine was added during the final 6h) increased [3H]thymidine incorporation into DNA to 180 ± 18% of the control[6].
In vivo, oral gavage administration of Fluoxymesterone (100mg/kg/day) to castrated Sprague Dawley rats for 6 weeks increased the weights of the levator ani muscle and prostate[7]. Intragastric administration of Fluoxymesterone (5mg/kg/day) to sedentary male Wistar rats for 8 weeks resulted in an increase in lysosomes of various morphologies in hepatocytes[8].
References:[1] Solomon Z J, Mirabal J R, Mazur D J, et al. Selective androgen receptor modulators: current knowledge and clinical applications[J]. Sexual medicine reviews, 2019, 7(1): 84-94.
[2] Vera-Badillo F E, Templeton A J, De Gouveia P, et al. Androgen receptor expression and outcomes in early breast cancer: a systematic review and meta-analysis[J]. Journal of the National Cancer Institute, 2014, 106(1): djt319.
[3] LARON Z V I. Use of fluoxymesterone in the treatment of growth retardation[J]. Acta Pædiatrica, 1963, 52(5): 465-472.
[4] Strickland A L. Long-term results of treatment with low-dose fluoxymesterone in constitutional delay of growth and puberty and in genetic short stature[J]. Pediatrics, 1993, 91(4): 716-720.
[5] Schuster D, Odermatt A. The Anabolic Androgenic Steroid Fluoxymesterone Inhibits 11b-Hydroxysteroid Dehydrogenase 2–Dependent Glucocorticoid Inactivation[J]. TOXICOLOGICAL SCIENCES, 2012, 126(2): 353-361.
[6] Kasperk C H, Wergedal J E, Farley J R, et al. Androgens directly stimulate proliferation of bone cells in vitro[J]. Endocrinology, 1989, 124(3): 1576-1578.
[7] Miner J N, Chang W, Chapman M S, et al. An orally active selective androgen receptor modulator is efficacious on bone, muscle, and sex function with reduced impact on prostate[J]. Endocrinology, 2007, 148(1): 363-373.
[8] Gragera R, Saborido A, Molano F, et al. Ultrastructural changes induced by anabolic steroids in liver of trained rats[J]. 1993.