sirolimus and icariin

The regenerative effect of Epimedium and its major bioactive flavonoid icariin (ICA) have been documented in traditional medicine, but their effect on sarcopenia has not been evaluated. The aim of this study was to investigate the effects of Epimedium extract (EE) on skeletal muscle as represented by differentiated C2C12 cells. Here we demonstrated that EE and ICA stimulated C2C12 myotube hypertrophy by activating several, including IGF-1 signal pathways. C2C12 myotube hypertrophy was demonstrated by enlarged myotube and increased myosin heavy chains (MyHCs). In similar to IGF-1, EE/ICA activated key components of the IGF-1 signal pathway, including IGF-1 receptor. Pre-treatment with IGF-1 signal pathway specific inhibitors such as picropodophyllin, LY294002, and rapamycin attenuated EE induced myotube hypertrophy and MyHC isoform overexpression. In a different way, EE induced MHyC-S overexpression can be blocked by AMPK, but not by mTOR inhibitor. On the level of transcription, EE suppressed myostatin and MRF4 expression, but did not suppress atrogenes MAFbx and MuRF1 like IGF-1 did. Differential regulation of MyHC isoform and atrogenes is probably due to inequivalent AKT and AMPK phosphorylation induced by EE and IGF-1. These findings suggest that EE/ICA stimulates pathways partially overlapping with IGF-1 signaling pathway to promote myotube hypertrophy.

Topics: Animals; Cell Differentiation; Cell Line; Chromones; Flavonoids; Gene Expression Regulation; Hypertrophy; Insulin-Like Growth Factor I; Mice; Morpholines; Myoblasts; Myosin Heavy Chains; Podophyllotoxin; Signal Transduction; Sirolimus

Autophagy is a conserved biological process, which is regulated by mTOR pathway and is reported to be a self-protective process of cancer cells to counteract apoptosis. Icariin is an active flavonoid that is reported to inhibit autophagy. In this study, we investigated whether Icariin could induce a reduction of cell proliferation by inhibiting autophagy. SKVCR cells, which are resistant to vincristine, were used for the investigation. We used CCK8 test and flow cytometry assay to study the effects of Icariin on cell proliferation, cell apoptosis and cell circle. We performed transmission electron microscope (TEM), immunohistochemical assay and western blotting assay to study the level of autophagy after Icariin treatment. Finally, we investigated whether the mTOR pathway is a target of Icariin by using mTOR inhibitor rapamycin and detected autophagy and apoptosis via flow cytometry assay, TEM, immunohistochemical assay and western blotting assay. Decreased proliferation and increased apoptosis was observed after Icariin treatment in SKVCR cells, together with decreased level of autophagy. Application of rapamycin could reverse the anti-autophagic and pro- apoptotic effect of Icariin. Icariin can inhibit autophagy and promote apoptosis in SKVCR cells by activating mTOR signal pathway. Icariin attenuates tumorigenesis by inhibiting autophagy and inducing apoptosis.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Autophagy; Cell Cycle; Cell Division; Cell Line, Tumor; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Drugs, Chinese Herbal; Female; Flavonoids; Humans; Molecular Targeted Therapy; Neoplasm Proteins; Ovarian Neoplasms; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Vincristine