securinine and Colonic-Neoplasms

To investigate the anti-tumor effects of L-securinine inducing colon cancer SW480 cell autophagy and explore its potential molecular mechanism.. MTT method was used to detect the antitumor effect of SW480 cells cultured with L-securinine in vitro. Light and electron microscopy were used to observe SW480 cells treated with L-securinine morphological changes. Flow cytometry was used to observe the apoptoticratio and cell cycle inducing with the L-securinine in SW480 cells, and the autophagic apoptosis ratio was determined by FITC-conjugated annexin V by flow cytometry (FCM). FCM was applied to analysis cell cycle; the expression of autophagy gene Beclin-1 was examined by reverse transcriptase polymerase chain reaction (RT-PCR).. The generation depression effects of SW480 cells cultured in vitro were detected byMTT method (Pb0.05), and there were dosage-time dependent relationships. Numerous autophagic vacuoles and empty vacuoles were observed in SW480 cells treated with 2.5 μM L-securinine for 48 h by electron microscopy, and the process of cell division that got less was observed.Through flow cytometry, a number of observed autophagic cells were obviously increased, and G1/S phase was retarded. L-Securinine tended to arrest cells at the G1 phase of the cell cycle. The percentage of the apoptotic cells increased as treatment duration and concentrations increased. Beclin-1 expression enhanced with L-securinine concentration increased.. L-Securinine has an anti-tumor effect against colon cancer SW480 cell. The L-securinine can induce striking autophagy in SW480 cell in vitro. The autophagy induced by L-securinine is related with upregulating the expression of autophagy gene Beclin-1.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Azepines; Beclin-1; Cell Cycle; Cell Line, Tumor; Colonic Neoplasms; Euphorbiaceae; Flow Cytometry; Gene Expression; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Bridged-Ring; Humans; Lactones; Membrane Proteins; Phytotherapy; Piperidines; Plant Extracts; Up-Regulation; Vacuoles

The identification of agents that preferentially kill cancer cells while protecting normal cells offers the potential to overcome toxicities found in many existing chemotherapeutic agents. Because p53 is frequently inactivated in cancer, agents that preferentially kill p53-null cells and protect wild-type p53-expressing cells are highly desirable chemotherapeutic agents. By using pairs of isogenic colon cancer cell lines that differ only in p53 expression (RKO and HCT116), securinine was found to exhibit these properties. Securinine (30 microM) induces apoptosis in 73% of p53-null HCT116 cells (LD(50) 17.5 microM) as opposed to 17.6% of HCT116 parental cells (LD(50) 50 microM) at 72 h after treatment. The mechanism of securinine-mediated death in p53-deficient cells involves the induction of the p53 family member, p73. Interestingly, the proapoptotic protein p73 is down-regulated in colon cancer cells expressing p53. This differential regulation of p73 in a p53-dependent fashion reveals a novel pathway for preferentially targeting cancer cells. In contrast to p53-deficient cells, cells expressing p53 are protected from cell death through the p53-mediated up-regulation of p21. These studies reveal a novel approach to specifically target colon cancer cells lacking p53 as well as identify a novel clinically relevant pathway to selectively induce p73 in p53-null cells.

Topics: Apoptosis; Azepines; Blotting, Western; Caspase Inhibitors; Caspases; Cell Adhesion; Cell Cycle; Cell Proliferation; Colonic Neoplasms; DNA Damage; DNA-Binding Proteins; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Bridged-Ring; Humans; Lactones; Nuclear Proteins; Piperidines; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tumor Cells, Cultured; Tumor Protein p73; Tumor Suppressor Protein p53; Tumor Suppressor Proteins