Abstract B07: s-SHIP promoter expression identifies a subset of murine basal prostate cells as neonatal stem cells
Authors: Brocqueville Guillaume , Roy Hélène Bauderlique Le , Rohrschneider Larry R. , Bourette Roland P. 
Published: August 2014

Abstract
The ability to isolate epithelial stem cells of the adult prostate (PrSCs) is crucial in terms of understanding their biology and purported role in tumor initiation. Previous isolations of PrSCs were based on subdividing total prostate epithelial cells by flow cytometry using antibodies to cell surface markers. In this study we have used a novel approach shown previously to successfully identify mammary stem cells (Bai & Rohrschneider, 2010, Genes Dev. 24:1882). This method employs the s-SHIP (stem-SH2-containing 5'-Inositol Phosphatase) promoter to tag presumptive stem cells with GFP in a transgenic mouse model, called Tg11.5kb-GFP.
Here we show that in Tg11.5kb-GFP mice, epithelial GFP+ (s-SHIP-expressing) cells are present transiently during early mouse prostate development: during the first week after birth, GFP expression was present in the growing buds in 1-3 % of total prostate cells, then decreased during the second week as the solid epithelial cords canalize. During this process, luminal and basal cells differenciate, and GFP+ cells localized in the basal cell layer of the epithelium. GFP expression was then totally turned off after 3 weeks. We therefore focused our study on epithelial GFP+ cells present between day 5 and day 7 after birth in order to determine if this population represents a population of putative stem cells. Cell surface marker analyses demonstrate an antigenic profile characteristic of basal epithelial prostate cells: lineage- CD24+ Sca-1+ CD49f+ (LSC). Interestingly, other research groups have shown that LSC population contains multipotent stem cells of the adult prostate; thus, the GFP+ cell population represent a subpopulation (~15%) of this basal/stem LSC population in the neonatal prostate. Moreover, in this LSC population, GFP+ cells showed ~20 fold more in vitro sphere-forming activity than the GFP- cells. Finally transplantation assays of 103 GFP+ cells in combination with urogenital sinus mesechymal cells demonstrated the potential of this GFP+ cell population to reconstitute in vivo prostate ducts containing both basal and luminal cells in renal grafts.
Altogether, these results demonstrate that s-SHIP promoter expression is a new marker for basal epithelial prostate cells exhibiting stem/progenitor cell properties. We are now performing transcriptional analysis of GFP+ and GFP- basal LSC cells in order to define gene sets that distinguish a basal cell profile from a tissue stem cell profile. Preliminary results showed interesting candidate genes including transcription factors. We anticipate that these results will lead to a better definition of adult PrSCs and will help to elucidate prostate cancer etiology.
Citation Format: Guillaume Brocqueville, Hélène Bauderlique Le Roy, Larry R. Rohrschneider, Roland P. Bourette. s-SHIP promoter expression identifies a subset of murine basal prostate cells as neonatal stem cells. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B07.