Wnt receptor Frizzled 8 is a target of ERG in prostate cancer.

Prostate cancer (PCa) is one of the most frequently diagnosed cancers among men. Many molecular changes have been detailed during PCa progression. The gene encoding the transcription factor ERG shows recurrent rearrangement, resulting in the overexpression of ERG in the majority of prostate cancers. Overexpression of ERG plays a critical role in prostate oncogenesis and development of metastatic disease. Among the downstream effectors of ERG, Frizzled family member FZD4 has been shown to be a target of ERG. Frizzled-8 (FZD8) has been shown to be involved in PCa bone metastasis. In the present study, we show that the expression of FZD8 is directly correlated with ERG expression in PCa. Furthermore, we show that ERG directly targets and activates FZD8 by binding to its promoter. This activation is specific to ETS transcription factor ERG and not ETV1. We propose that ERG overexpression in PCa leads to induction of Frizzled family member FZD8, which is known to activate the Wnt pathway. Taken together, these findings uncover a novel mechanism for PCa metastasis, and indicate that FZD8 may represent a potential therapeutic target for PCa.

Expression and Role of PAICS, a De Novo Purine Biosynthetic Gene in Prostate Cancer.

BACKGROUND: Our goal was to investigate de novo purine biosynthetic gene PAICS expression and evaluate its role in prostate cancer progression. METHODS: Next-generation sequencing, qRTPCR and immunoblot analysis revealed an elevated expression of a de novo purine biosynthetic gene, Phosphoribosylaminoimidazole Carboxylase, Phosphoribosylaminoimidazole Succinocarboxamide Synthetase (PAICS) in a progressive manner in prostate cancer. Functional analyses were performed using prostate cancer cell lines- DU145, PC3, LnCaP, and VCaP. The oncogenic properties of PAICS were studied both by transient and stable knockdown strategies, in vivo chicken chorioallantoic membrane (CAM) and murine xenograft models. Effect of BET bromodomain inhibitor JQ1 on the expression level of PAICS was also studied. RESULTS: Molecular staging of prostate cancer is important factor in effective diagnosis, prognosis and therapy. In this study, we identified a de novo purine biosynthetic gene; PAICS is overexpressed in PCa and its expression correlated with disease aggressiveness. Through several in vitro and in vivo functional studies, we show that PAICS is necessary for proliferation and invasion in prostate cancer cells. We identified JQ1, a BET bromodomain inhibitor previously implicated in regulating MYC expression and demonstrated role in prostate cancer, abrogates PAICS expression in several prostate cancer cells. Furthermore, we observe loss of MYC occupancy on PAICS promoter in presence of JQ1. CONCLUSIONS: Here, we report that evaluation of PAICS in prostate cancer progression and its role in prostate cancer cell proliferation and invasion and suggest it as a valid therapeutic target. We suggest JQ1, a BET-domain inhibitor, as possible therapeutic option in targeting PAICS in prostate cancer. Prostate 77:10-21, 2017. © 2016 Wiley Periodicals, Inc.

A Role for De Novo Purine Metabolic Enzyme PAICS in Bladder Cancer Progression.

Genomic and transcriptome sequencing of bladder cancer (BLCA) has identified multiple molecular alterations during cancer progression. Many of these identified genetic and epigenetic changes play a role in the progression of this disease. Studies have identified molecular subtypes in muscle-invasive bladder cancer (MIBC) with different sensitivities to frontline therapy suggesting the heterogeneity in these tumors and the importance of molecular characterization of MIBC to provide effective treatment. Specifically, it has become increasingly evident, as demonstrated by The Cancer Genome Atlas project, that metabolic enzymes are commonly dysregulated in BLCA. Elevated expression of multiple metabolic enzymes is due to the increased demand from rapidly proliferating BLCA cells requiring extensive nucleotide synthesis. Cancer cells utilize the de novo purine and pyrimidine biosynthetic pathway as a source of their nucleotide needs. In this study, we show that phosphoribosyl aminoimidazole succinocarboxamide synthetase (PAICS), an enzyme involved in de novo purine biosynthetic pathway, is significantly overexpressed in BLCA. Immunohistochemical staining of paraffin-embedded tissue sections showed that PAICS is overexpressed in MIBC. Furthermore, we found that tumor suppressor miR-128 negatively regulated PAICS expression by binding to its 3'-untranslated region. We also found that PAICS induces EMT by positively regulating SNAI1 and by a reduction in E-cadherin expression. Additionally, our in vitro functional studies and in vivo chicken chorioallantoic membrane assay show that PAICS plays a critical role in BLCA cell proliferation, invasion, and tumor growth. Collectively, our data suggest that targeting PAICS may provide a therapeutic option in BLCA.