Loss of dihydrotestosterone-inactivation activity promotes prostate cancer castration resistance detectable by functional imaging

Ziqi Zhu,Yoon-Mi Chung,Olga Sergeeva,Vladimir Kepe,Michael Berk,Jianneng Li,Hyun-Kyung Ko,Zhenfei Li,Marianne Petro,Frank P Difilippo,Zhenghong Lee,Nima Sharifi

doi:10.1074/jbc.ra118.004846

Abstract

Androgens such as testosterone and dihydrotestosterone are a critical driver of prostate cancer progression. Cancer resistance to androgen deprivation therapies ensues when tumors engage metabolic processes that produce sustained androgen levels in the tissue. However, the molecular mechanisms involved in this resistance process are unclear, and functional imaging modalities that predict impending resistance are lacking. Here, using the human LNCaP and C4-2 cell line models of prostate cancer, we show that castration treatment-sensitive prostate cancer cells that normally have an intact glucuronidation pathway that rapidly conjugates and inactivates dihydrotestosterone and thereby limits androgen signaling, become glucuronidation deficient and resistant to androgen deprivation. Mechanistically, using CRISPR/Cas9-mediated gene ablation, we found that loss of UDP glucuronosyltransferase family 2 member B15 (UGT2B15) and UGT2B17 is sufficient to restore free dihydrotestosterone, sustained androgen signaling, and development of castration resistance. Furthermore, loss of glucuronidation enzymatic activity was also detectable with a nonsteroid glucuronidation substrate. Of note, glucuronidation-incompetent cells and the resultant loss of intracellular conjugated dihydrotestosterone were detectable in vivo by 18F-dihydrotestosterone PET. Together, these findings couple a mechanism with a functional imaging modality to identify impending castration resistance in prostate cancers.

Highlights

Androgens such as testosterone and dihydrotestosterone are a critical driver of prostate cancer progression
UDP glucuronosyltransferase family 2 member B15 (UGT2B15) and UGT2B17 are the 2 major enzymes that are responsible for androgen glucuronidation in prostate cancer [10, 14]
The transition from LNCaP to the resistant C4-2 model is accompanied by a profound loss of expression of the glucuronidation machinery (Fig. 1, D and E), which accounts for the apparent switch in metabolic phenotype (Fig. 1A)

Summary

Introduction

Androgens such as testosterone and dihydrotestosterone are a critical driver of prostate cancer progression. Cancer resistance to androgen deprivation therapies ensues when tumors engage metabolic processes that produce sustained androgen levels in the tissue. Glucuronidation-incompetent cells and the resultant loss of intracellular conjugated dihydrotestosterone were detectable in vivo by 18F-dihydrotestosterone PET Together, these findings couple a mechanism with a functional imaging modality to identify impending castration resistance in prostate cancers. The long-standing standard treatment for advanced prostate cancer is androgen deprivation therapy by way of medical or surgical castration [1]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Tel.: 216-445-9750; Fax: prostate cancer (CRPC)2 [2, 3] This resistant state is frequently first heralded by a rising prostate-specific antigen (PSA), which is an androgen-responsive gene and is indicative of a reinstatement of androgen receptor (AR) stimulation [4]. There is a complete absence of functional imaging approaches that are informative of the metabolic state of the disease that provides information on tumor susceptibility to systemic therapies in the clinical standard of care

Methods

Results

Conclusion