Detection of androgen receptor (AR) and AR-V7 in small cell prostate carcinoma: Diagnostic and therapeutic implications

doi:10.1016/j.ajur.2018.09.003

Asian Journal of Urology, 2019, 6 (1): 109-113 doi: 10.1016/j.ajur.2018.09.003

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Detection of androgen receptor (AR) and AR-V7 in small cell prostate carcinoma: Diagnostic and therapeutic implications

Pei Zhao^a,Yezi Zhu^a,Liang Cheng^b,*(

),Jun Luo^a,*(

)

a Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
b Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA

Abstract
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Abstract

Objective: Small cell prostate carcinoma (SCPC) is a rare and highly malignant subtype of prostate cancer. SCPC frequently lacks androgen receptor (AR) and prostate-specific antigen (PSA) expression, and often responds poorly to androgen deprivation therapy (ADT). AR splice variant-7 (AR-V7) is a truncated AR protein implicated in resistance to AR-targeting therapies. AR-V7 expression in castration-resistant prostate cancers has been evaluated extensively, and blood-based detection of AR-V7 has been associated with lack of response to abiraterone and enzalutamide. However, whether AR-V7 is expressed in SCPC is not known.
Methods: Using validated antibodies, we performed immunohistochemistry (IHC) assay for the full-length AR (AR-FL) and (AR-V7) on post-ADT surgical SCPC specimens.
Results: Seventy-five percent (9/12) of the specimens showed positive staining for the AR-FL with various intensities. Thirty-three percent (4/12) of the specimens showed positive staining for AR-V7. Among the specimens with positive AR-V7 staining, two samples displayed very weak staining, one sample showed weak-to-moderate staining, and one sample showed strong staining. All positive specimens displayed a heterogeneous pattern of AR-FL/AR-V7 staining. All specimens positive for AR-V7 were also positive for AR-FL.
Conclusion: The study findings support the existence of measurable AR-FL and AR-V7 proteins in SCPC specimens. The results also have implications in detection of AR-V7 in specimens obtained through systemic sampling approaches such as circulating tumor cells. A positive AR-V7 finding by blood-based tests is not impossible in patients with SCPC who often demonstrate low PSA values.

Key words： Small cell prostate carcinoma Androgen receptor Androgen receptor splice variant-7 Immunohistochemistry

Received: 31 May 2018 Available online: 28 September 2018

Corresponding Authors: Liang Cheng,Jun Luo E-mail: liang_cheng@yahoo.com;jluo1@jhmi.edu

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Cite this article:

Pei Zhao,Yezi Zhu,Liang Cheng, et al. Detection of androgen receptor (AR) and AR-V7 in small cell prostate carcinoma: Diagnostic and therapeutic implications[J]. Asian Journal of Urology, 2019, 6(1): 109-113.

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http://www.ajurology.com/EN/10.1016/j.ajur.2018.09.003 OR http://www.ajurology.com/EN/Y2019/V6/I1/109

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