ER alpha-Targeted Therapy in Ovarian Cancer Cells by a Novel Estradiol-Platinum(II) Hybrid

作者：Brasseur K; Leblanc V; Fabi F; Parent S; Descoteaux C; Berube G; Asselin E^*

来源：Endocrinology, 2013, 154(7): 2281-2295.

DOI：10.1210/en.2013-1083

As we previously showed, we have synthesized a new family of 17 beta-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)-alpha in ER alpha-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 ER alpha-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 ER alpha-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 ER alpha -by 17 beta-estradiol Pt (II)-linked chemotherapeutic hybrids in these tumors. (Endocrinology 154: 2281-2295, 2013)

• 出版日期2013-7