928P - LHRH agonist-induced suppression of the androgen synthesis pathway in prostate cancer

Date 29 September 2012
Event ESMO Congress 2012
Session Poster presentation I
Topics Anti-Cancer Agents & Biologic Therapy
Prostate Cancer
Presenter Jacek Pinski
Authors J. Pinski1, S. Xiong2, Q. Wang2, S.V. Liu2
  • 1Medicine, University of Southern California Norris Comprehensive Cancer Center, 90033 - Los Angeles/US
  • 2Division Of Medical Oncology, University of Southern California Norris Comprehensive Cancer Center, 90033 - Los Angeles/US

Abstract

Background

Standard first-line therapy for advanced prostate cancer (PC) includes the use of a luteinizing hormone releasing hormone (LHRH) agonist. While the primary site of action for these agents is the pituitary-hypothalamic-gonadal axis, receptors fo LHRH are also present in the membrane of PC cells and mediate a direct anti-tumor effect. The mechanism of this effect has been largely unexplored and may harbor a context of vulnerability. Previously, we have demonstrated that luteinizing hormone (LH) increases de novo steroidogenesis in PC cells and silencing of the LH receptor leads to downregulation of steroidogenesis. Here, we examined the impact of LHRH agonists on this process at the cellular level.

Methods

LNCaP PC cells were treated with the LHRH agonist buserelin for 8 hours in the presence or absence of the LHRH antagonist antide. Gene expression of LH and androgen synthesis enzymes was quantified by real-time polymerase chain reaction and protein expression was measured with Western blot. Cell proliferation was assessed in these cells using MTS assays.

Results

The LHRH agonist buserelin significantly suppressed the gene expression of LH and the androgen synthesis enzymes AKR1C1, AKR1C2, AKR1C3, CYP11A1 and RDH5 (p < 0.05). Protein expression of LH, AKR1C1, AKR1C3 and CYP17A1 was also inhibited by buserelin treatment (p < 0.05). Buserelin also suppressed LNCaP cell proliferation in a dose-dependent manner (p < 0.05). The suppressive effects of buserelin on gene expression, protein expression and cell proliferation were mitigated by the LHRH antagonist antide.

Conclusion

These data implicate the LHRH agonist buserelin in the direct inhibition of de novo tumoral steroidogenesis, which may be mediated by suppression of LH. The LH pathway warrants further investigation as a therapeutic target.

Disclosure

All authors have declared no conflicts of interest.