Sensitization to the mitochondrial pathway of apoptosis augments melanoma tumor cell responses to conventional chemotherapeutic regimens

Cell Death Dis. 2012 Nov 15;3(11):e420. doi: 10.1038/cddis.2012.161.

Abstract

Metastatic malignant melanoma is highly resistant to chemotherapy, and the average survival rate is under 1 year. The only FDA-approved conventional chemotherapy (i.e., dacarbazine) targets melanoma tumor cells by inducing a form of cell death referred to as apoptosis. However, dacarbazine exhibits a response rate of ~5%, and combination chemotherapies consisting of cisplatin, vinblastine, and dacarbazine often offer little clinical advantage over dacarbazine alone. Apoptosis is governed by the BCL-2 family of proteins, which is comprised of anti-apoptotic and pro-apoptotic members. To determine if the anti-apoptotic BCL-2 repertoire established the cell death threshold and chemoresistance in melanoma, a novel treatment strategy was designed to inhibit the anti-apoptotic BCL-2 members with ABT-737. Using various melanoma model systems, we determined the affects of ABT-737 on sensitivity to dacarbazine-based regimens. Strikingly, ABT-737 re-sensitized melanoma cell lines to common chemotherapeutics leading to marked BIM-mediated apoptosis. Cellular features of the ABT-737 combination treatments were loss of proliferation, mitochondrial fragmentation, nuclear condensation, phosphatidylserine exposure, and decreased clonogenic survival. We also observed significant anti-tumor activity in an in vivo melanoma model system. Our data indicate that ABT-737 may be a beneficial adjuvant therapy to improve melanoma response rates when conventional chemotherapy is the only option.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Apoptosis*
  • Biphenyl Compounds / pharmacology*
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cisplatin / pharmacology
  • Humans
  • Melanoma / drug therapy
  • Melanoma / genetics
  • Melanoma / metabolism
  • Melanoma / physiopathology*
  • Mitochondria / drug effects*
  • Mitochondria / metabolism
  • Nitrophenols / pharmacology*
  • Piperazines / pharmacology
  • Proto-Oncogene Proteins c-bcl-2 / antagonists & inhibitors
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Sulfonamides / pharmacology*

Substances

  • ABT-737
  • Antineoplastic Agents
  • Biphenyl Compounds
  • Nitrophenols
  • Piperazines
  • Proto-Oncogene Proteins c-bcl-2
  • Sulfonamides
  • Cisplatin