Genome-wide functional genetic screen with the anticancer agent AMPI-109 identifies PRL-3 as an oncogenic driver in triple-negative breast cancers

// Hamid H. Gari 1 , Christy M. Gearheart 2 , Susan Fosmire 2 , Gregory D. DeGala 1 , Zeying Fan 1 , Kathleen C. Torkko 1 , Susan M. Edgerton 1 , M. Scott Lucia 1 , Rahul Ray 3 , Ann D. Thor 1 , Christopher C. Porter 2 and James R. Lambert 1 1 Department of Pathology, University of Colorado School of Medicine, Aurora, CO, USA 2 Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA 3 Department of Medicine, Boston University School of Medicine, Boston, MA, USA Correspondence to: James R. Lambert, email: // Keywords : AMPI-109, PRL-3, triple-negative breast cancer, phosphatase, functional genomics Received : December 22, 2015 Accepted : February 09, 2016 Published : February 17, 2016 Abstract Triple-negative breast cancers (TNBC) are among the most aggressive and heterogeneous cancers with a high propensity to invade, metastasize and relapse. Here, we demonstrate that the anticancer compound, AMPI-109, is selectively efficacious in inhibiting proliferation and inducing apoptosis of multiple TNBC subtype cell lines as assessed by activation of pro-apoptotic caspases-3 and 7, PARP cleavage and nucleosomal DNA fragmentation. AMPI-109 had little to no effect on growth in the majority of non-TNBC cell lines examined. We therefore utilized AMPI-109 in a genome-wide shRNA screen in the TNBC cell line, BT-20, to investigate the utility of AMPI-109 as a tool in helping to identify molecular alterations unique to TNBC. Our screen identified the oncogenic phosphatase, PRL-3, as a potentially important driver of TNBC growth, migration and invasion. Through stable lentiviral knock downs and transfection with catalytically impaired PRL-3 in TNBC cells, loss of PRL-3 expression, or functionality, led to substantial growth inhibition. Moreover, AMPI-109 treatment, downregulation of PRL-3 expression or impairment of PRL-3 activity reduced TNBC cell migration and invasion. Histological evaluation of human breast cancers revealed PRL-3 was significantly, though not exclusively, associated with the TNBC subtype and correlated positively with regional and distant metastases, as well as 1 and 3 year relapse free survival. Collectively, our study is proof-of-concept that AMPI-109, a selectively active agent against TNBC cell lines, can be used as a molecular tool to uncover unique drivers of disease progression, such as PRL-3, which we show promotes oncogenic phenotypes in TNBC cells.