Oral Presentation Annual Meetings of the Endocrine Society of Australia and Society for Reproductive Biology and Australia and New Zealand Bone and Mineral Society 2016

Transcriptome profiling of single prostate cancer cells in the castrate setting (#37)

Ashlee Clark 1 , Hieu Nim 1 , Natalie Lister 1 , Mark Frydenberg 1 , Mitchell Lawrence 1 , Gail Risbridger 1 , Renea Taylor 2
  1. Department of Anatomy and Developmental Biology, Monash University, Clayton, Vic, Australia
  2. Department of Physiology, Monash University, Clayton, Victoria, Australia

The standard of care for men with metastatic prostate cancer is androgen deprivation. Although initially all patients respond, resistance is inevitable and lethal castration-resistant prostate cancer ensues. Using patient-derived xenografts (PDX) of localised prostate tumours, we have identified a rare sub-population of ‘castration-tolerant’ prostate cancer cells that survive following castration.  The aim of this study was to molecularly characterise human castrate-tolerant prostate cancer cells and identify novel targeting strategies to eliminate them and delay disease progression. To study the genomic features of castrate-tolerant cells, we enriched for prostate cancer cells from PDXs and subjected them to single cell isolation and RNA sequencing. In the absence of a definitive cell–surface antigen for prostate cancer, we have developed a panel of 16 fluorescent surface-markers to enrich for tumour cells from PDX grafts. Using the Fluidigm C1 platform, we captured and sequenced > 50 cells from pre- and post-castration prostate cancer PDXs. Sequencing of isolated single cells and pooled populations was performed using the Illumina HiSeq in rapid mode with 50 bp fragment sequencing chemistry (3Million reads/cell).  Multidimensional scaling analysis showed that pre-castration and castrate-tolerant cells clustered separately, and that the response to castration is not uniform in all human cells, with variable degrees of heterogeneity seen within both groups. A unique gene set was identified in pre-castration versus castrate-tolerant luminal cells; we identified distinct changes in energy metabolism, including suppression of ATP production, that aid cell survival and detected a consistent upregulation of the retinoic acid signaling pathway, including upregulation of CRABP2 and RARRES3 expression in castrate-tolerant cells. This is the first study to report gene expression in single human prostate cells and revealed novel endocrine-related changes prior to and following androgen deprivation. Our data suggest that further and/or alterative hormone suppression may be effective in targeting castration-tolerant prostate cancer cells.