cytochrome-c-t and hirsutine

The aim of this study was to investigate the effects of hirsutine on apoptosis of breast cancer cells and its possible mechanism. The MCF-10A, MCF-7 and MDA-MB-231 cells were treated with hirsutine at different concentrations for 48 h or incubated with 160 μmol/L hirsutine for 24, 48, and 72 h. The MCF-10A cell line is a non-tumorigenic epithelial cell line, and the MCF-7 and MDA-MB-231 are human breast adenocarcinoma cell lines. CCK-8 assay was employed to detect the cell viability. Flow cytometry was used to assay the apoptosis and mitochondrial membrane potential (MMP). The protein expressions of Bcl-2, Bax, cleaved-caspase 9, cleaved-caspase 3 and cytochrome C (Cyt C) in the MDA-MB-231 cells were detected by Western blotting. The results showed that hirsutine remarkably reduced the viability of MCF-7 and MDA-MB-231 cells in a time- and dose-dependent manner (P < 0.05) with IC50 values of 447.79 and 179.06 μmol/L, respectively. In the MDA-MB-231 cells, hirsutine induced apoptosis and depolarization of MMP (P < 0.05), released Cyt C from mitochondria (P < 0.05), and activated caspase 9 and caspase 3 (P < 0.05). However, these effects induced by hirsutine were all inhibited by cyclosporin A (CsA) (P < 0.05), a specific inhibitor of mitochondrial permeability transition pore (MPTP). In addition, hirsutine down-regulated the protein level of Bcl-2 and up-regulated the protein level of Bax (P < 0.05). These results suggest that hirsutine may induce apoptosis of human breast cancer MDA-MB-231 cells through decreasing the ratio of Bcl-2 to Bax, opening MPTP, releasing Cyt C from mitochondria, and activating caspase 9 and caspase 3.

Topics: Alkaloids; Apoptosis; bcl-2-Associated X Protein; Breast Neoplasms; Caspase 3; Caspase 9; Cell Line, Tumor; Cell Survival; Cytochromes c; Humans; MCF-7 Cells; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Proto-Oncogene Proteins c-bcl-2

Hirsutine extracted from Uncaria rhynchophylla has been shown to exhibit anti-cancer activity. However, the molecular mechanism by which hirsutine exhibits anti-lung cancer activity remains unclear. In the present study, we showed that hirsutine induces apoptosis in human lung cancer cells via loss of mitochondrial membrane potential (∆ψm), adenosine triphosphate (ATP) depletion, ROS production, as well as cytochrome c release. Dephosphorylation of GSK3β is involved in hirsutine-mediated mitochondrial permeability transition pore (mPTP) opening through ANT1/CypD interaction. Mechanistic study revealed that interruption of ROCK1/PTEN/PI3K/Akt signaling pathway plays a critical role in hirsutine-mediated GSK3β dephosphorylation and mitochondrial apoptosis. Our in vivo study also showed that hirsutine effectively inhibits tumor growth in a A549 xenograft mouse model through ROCK1/PTEN/PI3K/Akt signaling-mediated GSK3β dephosphorylation and apoptosis. Collectively, these findings suggest a hierarchical model in which induction of apoptosis by hirsutine stems primarily from activation of ROCK1 and PTEN, inactivation of PI3K/Akt, leading in turn to GSK3β dephosphorylation and mPTP opening, and culminating in caspase-3 activation and apoptosis. These findings could provide a novel mechanistic basis for the application of hirsutine in the treatment of human lung cancer.

Topics: A549 Cells; Adenine Nucleotide Translocator 1; Adenosine Triphosphate; Alkaloids; Animals; Apoptosis; Cell Proliferation; Cyclophilins; Cytochromes c; Glycogen Synthase Kinase 3 beta; Humans; Lung Neoplasms; Membrane Potential, Mitochondrial; Mice, Nude; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Models, Biological; Peptidyl-Prolyl Isomerase F; Phosphatidylinositol 3-Kinases; Phosphorylation; PTEN Phosphohydrolase; Reactive Oxygen Species; rho-Associated Kinases; Signal Transduction; Xenograft Model Antitumor Assays