title: Anti-Leukemic Activity of Shikonin: Role of ERP57 in Shikonin Induced Apoptosis in Acute Myeloid Leukemia.
abstract: OBJECTIVE
  ER-Stress and activation of unfolded protein response belong to the major factors involved in chemoresistance in cancer cells. In this study we investigated the effect of shikonin on the survival of acute myeloid leukemia cells and the role of ER-stress protein ERP57, a protein disulfide isomerase, in improvement of chemotherapy.
  
  
  METHODS
  Using MTT assay we studied cytotoxic effects of shikonin on HL-60 cells. The flow cytometry was adopted to examine the shikonin induced mode of cell death in HL-60 cells. The overall protein expression alteration resulting from shikonin treatment was investigated using proteomics methods. Western blotting was performed to quantify the alteration in protein expression in HL-60 after shikonin treatment. Silencing and overexpression studies were carried out to highlight the therapeutic role of ERP57 in shikonin effect on AML cells.
  
  
  RESULTS
  Shikonin induces apoptosis in HL-60 cells without significant effect on Primary cells from healthy volunteers. The apoptotic effect was dose and time dependent and was accompanied by strong alteration in cell proteome. Among the proteins targeted by shikonin, ERP57 was significantly downregulated in HL-60 after treatment. Compared to healthy control ERP57 was found to be highly expressed in AML cell line HL60 and was downregulated after shikonin treatment. Overexpression of ERP57 protected HL-60 from shikonin induced apoptosis, whereas knockdown of ERP57 expression resulted in increase in shikonin induced apoptosis.
  
  
  CONCLUSIONS
  Our results demonstrate that ERP57 plays a crucial role in resistance towards shikonin induced apoptosis in AML cells. Targeting of ERP57 might offer a new therapeutic option for the treatment of acute myeloid leukemia.
authors.affiliation: Clinic for Nephrology and Rheumatology, University Medical Centre, Georg-August University, Gx00F6;ttingen, Germany.
authors.forename: Rachana
authors.initials: R
authors.lastname: Trivedi
authors.forename: Gerhard A
authors.initials: GA
authors.lastname: Müller
authors.forename: Manohar S
authors.initials: MS
authors.lastname: Rathore
authors.forename: Durga P
authors.initials: DP
authors.lastname: Mishra
authors.forename: Hassan
authors.initials: H
authors.lastname: Dihazi
mesh_terms: D000208:Acute Disease; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology; D015180:Electrophoresis, Gel, Two-Dimensional; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D005434:Flow Cytometry; D018922:HL-60 Cells; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015394:Molecular Structure; D009285:Naphthoquinones / Q000737:chemistry / Q000494:pharmacology*; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism*; D020543:Proteome / Q000187:drug effects / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D034622:RNA Interference; D013997:Time Factors; D014415:Tunicamycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000970:Antineoplastic Agents; D004365:Drugs, Chinese Herbal; D009285:Naphthoquinones; D020543:Proteome; D014415:Tunicamycin; C016101:shikonin; D019704:Protein Disulfide-Isomerases; C085868:PDIA3 protein, human