These findings provide new therapeutic perspectives for the treatment of muscle injuries, sarcopenia, and cachectic disease, but also imply that such a substance could be abused for doping purposes.

Background: Breast cancer is the most frequently diagnosed malignancy among women and the second leading cause of cancer death worldwide. Among which nuclear estrogen receptor (nER) negative breast cancer is always with much poor prognosis. Recently, membrane G protein coupled estrogen receptor (GPER), a newly recognized estrogen receptor has been documented to take essential part in the development and treatment of breast cancer. The present study was designed to investigate the anti nER negative breast cancer effect of cryptotanshinone (CPT), an important active compound of traditional Chinese medicine Danshen and its possible molecular pathway. Methods: The following in vitro tests were performed in nER negative but GPER positive breast cancer SKBR-3 cells. The effect of CPT on cell proliferation rate and cell cycle distribution was evaluated by MTT cell viability test and flow cytometry assay respectively. The role of PI3K/AKT pathway and the mediated function of GPER were tested by western blot and immunofluorescence. Technique of gene silence and the specific GPER agonist G-1 and antagonist G-15 were employed in the experiments to further verify the function of GPER in mediating the anticancer role of CPT. Results: The results showed that proliferation of SKBR-3 cells could be blocked by CPT in a time and dose dependent manner. CPT could also exert antiproliferative activities by arresting cell cycle progression in G1 phase and down regulating the expression level of cyclin A, cyclin B, cyclin D and cyclin-dependent kinase 2 (CDK2). The antiproliferative effect of CPT was further enhanced by G-1 and attenuated by G-15. Results of western blot and immunofluorescence showed that expression of PI3K and p-AKT could be downregulated by CPT and such effects were mediated by GPER which were further demonstrated by gene silence test. Conclusion: The current study showed that the antiproliferative action of CPT on SKBR-3 cells was realized by inhibition of GPER mediated PI3K/AKT pathway. These findings provide further validation of GPER serving as useful therapeutic target.

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Skeletal muscle loss during menopause is associated with a higher risk of developing diabetes type II and the general development of the metabolic syndrome. Therefore, strategies combining nutritional and training interventions to prevent muscle loss are necessary. Danshen Si Wu is a traditional Chinese medicine used for menopausal complains. One of the main compounds of Danshen Si Wu is tanshinone IIA. Physiological effects of tanshinone IIA have been described as being mediated via the estrogen receptor. Therefore, it was the aim of this study to determine its tissue specific ERα- and ERβ-mediated estrogenic activity, to investigate its antiestrogenic properties, and, particularly, to study estrogen receptor-mediated biological responses to tanshinone IIA on skeletal muscle cells. The purity of tanshinone IIA was analyzed by LC-DAD-MS/MS analysis. ERα/ERβ-mediated activity was dose-dependently analyzed in HEK 239 cells transfected with ERα or ERβ expression vectors and respective reporter genes. Androgenic, antiandrogenic, and antiestrogenic properties of tanshinone IIA were analyzed in a yeast reporter gene assay. The effects of tanshinone IIA on proliferation and cell cycle distribution were investigated in ERα positive T47D breast cancer cells. The ability of tanshinone IIA to stimulate estrogen receptor-mediated myotube hypertrophy was studied in C2C12 myoblastoma cells. Our data show that tanshinone IIA is quite potent at stimulating ERα and ERβ reporter genes with comparable efficacy. Tanshinone IIA displayed antiestrogenic and also antiandrogenic properties in a yeast reporter gene assay. It inhibited the growth of T47D breast cancer cells by suppressing proliferation and arresting the cells in G0/G1. Tanshinone IIA also stimulated the hypertrophy of C2C12 myotubes via an estrogen receptor-mediated mechanism. Summarizing our results, tanshinone IIA can be characterized as an estrogen receptor partial agonist with antiandrogenic properties. It seems to inhibit ERα-mediated cell proliferation but induces ERβ-related biological responses like hypertrophy of myotubes. These findings are interesting with respect to the treatment of a variety of complains of postmenopausal females, including muscle wasting.

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