Characterizing ERG-Mediated Transcriptional Reprogramming of Prostatic Epithelial Cells towards a Cancer Stem Cell Phenotype
Session type: Poster / e-Poster / Silent Theatre session
ERG expression commonly occurs in prostate cancer (PCa). While often linked to poor prognosis, how ERG might mechanistically promote transformation remains to be elucidated.
ERG-expressing RWPE1 prostatic epithelial cells (ERG-RWPE1) were constructed to test whether ERG transformation is caused by specific transcriptional profile changes. Microarray analysis of ERG-RWPE1 cells demonstrated up-regulation transcription of stem cell (SC)-related genes. Expression of the SC markers PROM1, c-KIT and CD33 were confirmed at the protein level by FACS and immunofluorescence. The transcriptional reprogramming events related to SC-like capacity were confirmed at mRNA in ERG-RWPE-1 attached and spheroid cultures.
ERG-RWPE1 cells form self-renewable spheroids when cultured in non-adherent SC media. Spheroids uniformly express PROM1, c-KIT and CD33 and when re-plated in adherent conditions, re-establish the SC marker expression pattern of the parental adherent cultures. Transcript analysis of ERG-RWPE-1 spheroid cultures also revealed activation of transcriptional reprogramming events related to acquisition of SC-like capacity, including up-regulated expression of a panel of “Yamanaka-related” SC genes (OCT3/4, SOX2, MYC and KLF4), epigenetic control (PRC1, PRC2 and Homeobox C family genes) and genes belonging to DNA methyltransferase, long noncoding RNA and hypoxia pathways.
RWPE1–ERG cells exhibit up regulated expression of SC genes. ERG induces the formation of self-renewable prostaspheres that exhibit enriched expression of membrane SC markers including (PROM1, c-KIT and CD33). Prostaspheres and attached cells have different gene expression in the family groups of Transcription Factors (Yamanaka Factors), PRC1, PRC2, Homeobox C family, DNA Methyltransferase and long non-coding RNA. Prostaspheres functional groups rank Pluripotency > Maintenance > Differentiation. The genes of the Family groups are interconnected and form a complex network of interactions. This system is a useful model to interrogate the molecular mechanisms of transformation and control of cancer SC leading to the design of new therapies for prostate cancer.