title: Evidence for the association of synaptotagmin with glutathione S-transferases: implications for a novel function in human breast cancer.
abstract: OBJECTIVE
  To analyze the pattern of changes in GSTs in cancerous and adjacent non-cancerous tissues obtained from breast cancer patients undergoing surgery.
  
  
  METHODS
  Cytosolic GST purification, assay of GST, protein expression levels, and GST-synaptotagmin association were analyzed using standard biochemical techniques like GSH-affinity purification, spectrophotometry, SDS-PAGE, Western blots, and matrix-assisted laser desorption and ionization-time of flight (MALDI-TOF).
  
  
  RESULTS
  GST activity in cancerous tissues (0.26 U/mg protein) was significantly higher (P < 0.05) as compared to those from adjacent non-cancerous tissues (0.14 U/mg protein) of breast cancer patients. Further analysis of GST subunits on SDS-PAGE and Western blots using class-specific GST antibodies revealed significant elevation in GST-pi levels in cancer tissues with no appreciable changes in GST-alpha and GST-mu. Along with the elevation of GST-pi levels, high molecular weight proteins (approximately 70 kDa) cross reacting with GST antibodies were detected only in surgically resected tumor biopsies but not in the non-cancerous tissues adjacent to the tumor. Based on MALDI-TOF analysis, the high molecular weight band was identified as synaptotagmin V bound to GST-M1 with 47% sequence coverage after processing on an MS-FIT search engine.
  
  
  CONCLUSIONS
  Our results suggest a novel putative functional role for the GST-synaptotagmin complex in human breast cancers. As this association of GST M1-synaptotagmin was not seen in adjacent non-cancerous tissues, this can be used as a marker for breast cancers.
authors.affiliation: Department of Animal Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India.
authors.forename: A S
authors.initials: AS
authors.lastname: Sreenath
authors.forename: K Ravi
authors.initials: KR
authors.lastname: Kumar
authors.forename: G V
authors.initials: GV
authors.lastname: Reddy
authors.forename: B
authors.initials: B
authors.lastname: Sreedevi
authors.forename: D
authors.initials: D
authors.lastname: Praveen
authors.forename: S
authors.initials: S
authors.lastname: Monika
authors.forename: S
authors.initials: S
authors.lastname: Sudha
authors.forename: M Gopal
authors.initials: MG
authors.lastname: Reddy
authors.forename: P
authors.initials: P
authors.lastname: Reddanna
mesh_terms: D000328:Adult; D015153:Blotting, Western; D001940:Breast / Q000201:enzymology; D001943:Breast Neoplasms / Q000201:enzymology / Q000503:physiopathology*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D018270:Carcinoma, Ductal, Breast / Q000201:enzymology / Q000503:physiopathology; D002846:Chromatography, Affinity; D005260:Female; D005982:Glutathione Transferase / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D050857:Synaptotagmins
chemical_list: D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; C494295:SYT5 protein, human; D050857:Synaptotagmins; D005982:Glutathione Transferase