title: Potent induction of apoptosis by beta-lapachone in human multiple myeloma cell lines and patient cells.
abstract: BACKGROUND
  Human multiple myeloma (MM) remains an incurable hematological malignancy. We have reported that beta-lapachone, a pure compound derived from a plant, can induce cell death in a variety of human carcinoma cells, including ovary, colon, lung, prostate, pancreas, and breast, suggesting a wide spectrum of anticancer activity.
  
  
  METHODS
  We first studied antisurvival effects of beta-lapachone in human MM cells by colony formation assay. To determine whether the differential inhibition of colony formation occurs through antiproliferative activity, we performed MTT assays. The cytotoxicity of beta-lapachone on human peripheral blood mononuclear cells was also measured by MTT assay. To determine whether the cell death induced by beta-lapachone occurs through necrosis or apoptosis, we used the propidium iodide staining procedure to determine the sub-GI fraction, Annexin-V staining for externalization of phosphatidylserine, and fragmentation of cellular genomic DNA subjected to gel electrophoresis. To investigate the mechanism of anti-MM activity, we examined Bcl-2 expression, cytochrome C release, and poly (ADP ribose) polymerase cleavage by Western blot assay.
  
  
  RESULTS
  We found that beta-lapachone (less than 4 microM) inhibits cell survival and proliferation by triggering cell death with characteristics of apoptosis in ARH-77, HS Sultan, and MM.1S cell lines, in freshly derived patient MM cells (MM.As), MM cell lines resistant to dexamethasone (MM.1R), doxorubicin (DOX.40), mitoxantrone (MR.20), and mephalan (LR5). Importantly, after treatment with beta-lapachone, we observed no apoptosis in peripheral blood mononuclear cells in either quiescent or proliferative states, freshly isolated from healthy donors. In beta-lapachone treated ARH-77, cytochrome C was released from mitochondria to cytosol, and poly (ADP ribose) polymerase was cleaved, signature events of apoptosis. Finally, the apoptosis induced by beta-lapachone in MM cells was not blocked by either interleukin-6 or Bcl-2, which confer multidrug resistance in MM.
  
  
  CONCLUSIONS
  Our results suggest potential therapeutic application of beta-lapachone against MM, particularly to overcome drug resistance in relapsed patients.
authors.affiliation: Dana-Farbe Cancer Institute, Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA. Youzhi_Li@dfci.harvard.edu
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: C J
authors.initials: CJ
authors.lastname: Li
authors.forename: D
authors.initials: D
authors.lastname: Yu
authors.forename: A B
authors.initials: AB
authors.lastname: Pardee
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis; D015153:Blotting, Western; D002455:Cell Division; D002470:Cell Survival; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000473:pathology*; D009285:Naphthoquinones / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012008:Recurrence; D014407:Tumor Cells, Cultured
chemical_list: D000903:Antibiotics, Antineoplastic; D003574:Cytochrome c Group; D009285:Naphthoquinones; D019253:Proto-Oncogene Proteins c-bcl-2; C014638:beta-lapachone