Abstract 1854: Generation and characterization of mouse model of Pmepa1 conditional knockout in prostate epithelia
Authors: Li Hua , Sharad Shashwat , Barbiev Talai , Song Yingjie , Young Denise , Sreenath Taduru , Dobi Albert , Srivastava Shiv 
Published: July 2017

Abstract
Introduction and Objectives: Prostate cancer (CaP) is the most common non-skin malignancy diagnosed in American men and desfunctions of androgen receptor (AR) plays an essential role in prostate tumorigenesis. PMEPA1 is an androgen and TGF-β -induced gene abundant in prostate, which was identified to degrade AR protein via NEDD4 E3 ligase mediated pathway. Reduced or loss of PMEPA1 expression, commonly detected in prostate tumors, led to increased AR protein and activated AR signaling. PMEPA1 inhibited TGF-β receptor 1 meditated signaling by a negative feedback loop. It was reported that loss of PMEPA1 facilitates bone metastasis of CaP through blocking TGF-β signaling. To further investigating the biological function of PMEP1 gene in CaP tumorigenesis, particularly via AR and TGF-β, we generated Pmepa1 prostate conditional knockout mouse model.
Methods: C57BL/6 mice were utilized for generation of Pmepa1 conditional knockout model. Pmepa1 gene was conditionally deleted in mouse prostate epithelium by ARR2PB-Cre-Lox system. Male mice of genotypes of wild-type, Pmepa1 flox/wild-type-ARR2PB-Cre, Pmepa1 flox/flox-ARR2PB-Cre were euthanized at the age of 3 months for analysis. The prostate tissue was collected for frozen and formalin fixation for histology analysis, and other major organs including heart, lung, liver, spleen, bladder and testis were also collected for control. The tissue were sectioned and stained with Hematoxylin & Erosin (H&E). Total RNA and protein were harvested by homogenizing tissue. The protein levels of Pmepa1, Ar and Nkx3.1 were analyzed by immunohistochemistry (IHC) and immunoblotting, and the transcript levels of these genes were evaluated by in situ hybridization (ISH) and quantitative-PCR (Q-PCR).
Results: The expression of Pmepa1 protein was found to focus on lateral lobe, consistent with Ar protein expression pattern. The data of Q-PCR and ISH showed that transcript level of Pmepa1 was dramatically suppressed in Pmepa1 flox/flox and flox/wild-type ARR2PB-Cre mice. Compared to wild-type ones, Pmepa1 protein was shown significantly decreased in heterozygous and homozygous knockout mice by immunoblotting and IHC staining. And the protein level of Ar was stronger in Pmepa1 conditional deleted mouse. There was no dramatic morphology change in mouse prostate gland by H&E staining.
Conclusions: Conditional deletion of Pmepa1 gene in mouse prostate epithelium led to enhanced Ar protein and activating Ar signaling. The effects of Pmepa1 gene loss in mouse prostate gland on other signaling such as TGF-β and prostate tumorigenesis are needed to be further evaluated.
Funding: This study was supported by CPDR, USUHS, HU0001-10-2-0002 to DGM.
Citation Format: Hua Li, Shashwat Sharad, Talai Barbiev, Yingjie Song, Denise Young, Taduru Sreenath, Albert Dobi, Shiv Srivastava. Generation and characterization of mouse model of Pmepa1 conditional knockout in prostate epithelia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1854. doi:10.1158/1538-7445.AM2017-1854