title: Crotoxin induces apoptosis and autophagy in human lung carcinoma cells in vitro via activation of the p38MAPK signaling pathway.
abstract: OBJECTIVE
  Crotoxin (CrTX) is the primary toxin in South American rattlesnake (Crotalus durissus terrificus) venom, and exhibits antitumor and other pharmacological actions in vivo and in vitro. Here, we investigated the molecular mechanisms of the antitumor action of CrTX in human lung carcinoma cells in vitro.
  
  
  METHODS
  Human lung squamous carcinoma SK-MES-1 cells were tested. The cytotoxicity of CrTX was evaluated in both MTT and colony formation assays. Cell cycle was investigated with flow cytometry. Cell apoptosis was studied with Hoechst 33258 and Annexin V-FITC staining. The levels of relevant proteins were analyzed using Western blot assays.
  
  
  RESULTS
  CrTX (25, 50, 100 μmol/L) inhibited the growth and colony formation of SK-MES-1 cells in dose- and time-dependent manners. CrTX increased the proportion of S phase cells and dose-dependently induced cell apoptosis, accompanied by down-regulating the expression of proliferating cell nuclear antigen (PCNA), and increasing the level of cleaved caspase-3. Furthermore, CrTX dose-dependently increased the expression of autophagy-related proteins LC3-II and beclin 1, and decreased the level of p62 in the cells. Moreover, CrTX (50 μmol/L) significantly increased p38MAPK phosphorylation in the cells. Pretreatment of the cells with SB203580, a specific inhibitor of p38MAPK, blocked the inhibition of CrTX on cell proliferation, as well as CrTX-induced apoptosis and cleaved caspase-3 expression.
  
  
  CONCLUSIONS
  The p38MAPK signaling pathway mediates CrTX-induced apoptosis and autophagy of human lung carcinoma SK-MES-1 cells in vitro.
authors.affiliation: College of Pharmaceutical Science, Soochow University, Suzhou 215123, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Han
authors.affiliation: College of Pharmaceutical Science, Soochow University, Suzhou 215123, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Liang
authors.affiliation: College of Pharmaceutical Science, Soochow University, Suzhou 215123, China.
authors.forename: Zheng-hong
authors.initials: ZH
authors.lastname: Qin
authors.affiliation: College of Pharmaceutical Science, Soochow University, Suzhou 215123, China.
authors.forename: Chun-yu
authors.initials: CY
authors.lastname: Liu
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects*; D000071186:Beclin-1; D002277:Carcinoma / Q000188:drug therapy* / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003439:Crotoxin / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D016196:S Phase / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; C477012:MAP1LC3A protein, human; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C118585:P62 protein, human; D018809:Proliferating Cell Nuclear Antigen; D016601:RNA-Binding Proteins; D003439:Crotoxin; D048051:p38 Mitogen-Activated Protein Kinases; D053148:Caspase 3