title: A novel polypeptide extracted from Ciona savignyi induces apoptosis through a mitochondrial-mediated pathway in human colorectal carcinoma cells.
abstract: BACKGROUND
  Sessile marine animals such as sponges, ascidians, and bryozoans are a rich source of bioactive natural products, many of which exhibit potent anticancer activity.
  
  
  METHODS
  We extracted and purified a polypeptide with potent antitumor activity from Ciona savignyi by acetone fractionation, ultrafiltration, ion exchange chromatography, gel chromatography, and high-performance liquid chromatography. An MTT assay was used to study the cytotoxicity of the isolated fraction and the purified polypeptide. Cell cycle and Western blot analysis were performed to study the mode of action of the purified polypeptide.
  
  
  RESULTS
  A novel polypeptide with potent antitumor activity was purified. The molecular weight of the polypeptide, designated CS5931, was 5931 Da, and use of the genome basic local alignment search tool (BLAST) revealed that the N-terminal sequence of CS5931 is identical to that of granulin A from C savignyi. CS5931 exhibited significant cytotoxicity for several cancer cell types and induced apoptotic death in HCT-8 cells in a dose- and time-dependent manner. Cell cycle analysis demonstrated that CS5931 caused cell cycle arrest at the G(2)/M phase, and a sub-G(1) peak appeared after treating the cells with CS5931 for 12 hours. The mitochondrial-mediated pathway was implicated in CS5931-induced apoptosis.
  
  
  CONCLUSIONS
  Our observations clearly demonstrate the antiproliferative and proapoptotic activities of the polypeptide CS5931 from C savignyi and the mitochondrial-mediated pathway involved in the polypeptide-induced cell death.
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Linyou
authors.initials: L
authors.lastname: Cheng
authors.forename: Chunguang
authors.initials: C
authors.lastname: Wang
authors.forename: Haizhou
authors.initials: H
authors.lastname: Liu
authors.forename: Fengxia
authors.initials: F
authors.lastname: Wang
authors.forename: Lanhong
authors.initials: L
authors.lastname: Zheng
authors.forename: Jin
authors.initials: J
authors.lastname: Zhao
authors.forename: Edward
authors.initials: E
authors.lastname: Chu
authors.forename: Xiukun
authors.initials: X
authors.lastname: Lin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D000077155:Granulins; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D008928:Mitochondria / Q000378:metabolism*; D010455:Peptides / Q000302:isolation & purification / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014561:Urochordata; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C494826:BAX protein, human; D000077155:Granulins; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; D053148:Caspase 3; D053453:Caspase 9