ERα-targeted therapy in ovarian cancer cells by a novel estradiol-platinum(II) hybrid

Endocrinology. 2013 Jul;154(7):2281-95. doi: 10.1210/en.2013-1083. Epub 2013 May 15.

Abstract

As we previously showed, we have synthesized a new family of 17β-estradiol-platinum(II) hybrids. Earlier studies revealed the VP-128 hybrid to show high efficiency compared with cisplatin toward hormone-dependent breast cancer cells. In the present research, we have studied the antitumor activity of VP-128 in vitro and in vivo against ovarian cancer. In nude mice with ovarian xenografts, VP-128 displayed selective activity toward hormone-dependent tumors and showed higher efficiency than cisplatin to inhibit tumor growth. Similarly, in vitro, transient transfection of estrogen receptor (ER)-α in ERα-negative A2780 cells increased their sensitivity to VP-128-induced apoptosis, confirming the selectivity of VP-128 toward hormone-dependent tumor cells. In agreement, Western blot analysis revealed that VP-128 induced higher caspase-9, caspase-3, and poly (ADP-ribose) polymerase cleavage compared with cisplatin. The activation of caspase-independent apoptosis was also observed in ERα-negative A2780 cells, in which VP-128 rapidly induced the translocation of apoptosis-inducing factor to the nucleus. Conversely, subcellular localization of apoptosis-inducing factor was not modified in ERα-positive Ovcar-3 cells. We also discovered that VP-128 induces autophagy in ovarian cancer cells because of the formation of acidic vesicular organelles (AVOs) and increase of Light Chain 3B-II protein responsible for the formation of autophagosomes; pathways related to autophagy (AKT and mammalian target of rapamycin) were also down-regulated, supporting this mechanism. Finally, the inhibition of autophagy using chloroquine increased VP-128 efficiency, indicating a possible combination therapy. Altogether these results highlight the beneficial value of VP-128 for the treatment of hormone-dependent ovarian cancers and provide preliminary proof of concept for the efficient targeting of ERα- by 17β-estradiol-Pt(II)-linked chemotherapeutic hybrids in these tumors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Annexin A5 / metabolism
  • Anticarcinogenic Agents / pharmacology
  • Anticarcinogenic Agents / therapeutic use*
  • Blotting, Western
  • Cell Line, Tumor
  • Estradiol / chemistry
  • Estradiol / pharmacology*
  • Estradiol / therapeutic use*
  • Estrogen Receptor alpha / genetics
  • Estrogen Receptor alpha / metabolism*
  • Female
  • Fluorescent Antibody Technique
  • Humans
  • Lentivirus / genetics
  • Mice
  • Mice, Nude
  • Ovarian Neoplasms / drug therapy*
  • Ovarian Neoplasms / metabolism
  • Platinum Compounds / chemistry
  • Platinum Compounds / pharmacology*
  • Platinum Compounds / therapeutic use*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Xenograft Model Antitumor Assays

Substances

  • Annexin A5
  • Anticarcinogenic Agents
  • ESR1 protein, human
  • Estrogen Receptor alpha
  • Platinum Compounds
  • Estradiol