Role of C10orfl12 in Prostate Cancer
Abstract
Scientific Rationale, Objectives, and Aims: Prostate cancer (PCa) is the second most commonly diagnosed cancer in American men. Prostate cancer that has developed resistance to androgen deprivation therapy, termed castration-resistant prostate cancer (CRPC), is a lethal disease. It is estimated that over 26,000 men in the United States will die from PCa this year, mostly due to metastatic CRPC. New drugs are thus urgently needed to treat CRPC. Genes and molecular pathways that are de-regulated in CRPC may be causatively associated with the disease and represent promising targets for therapeutic intervention. Among the most upregulated genes in CRPC, relative to less aggressive and localized PCa, is EZH2. EZH2 is a bona fide oncogene whose upregulation has been shown to promote PCa cell cycle progression, cell proliferation, migration, and invasion in vitro and tumor growth in vivo. Mechanistically, EZH2 is an enzyme that catalyzes methylation of Histone H3 at Lysine 27, a modification that turns off gene expression. In the last decade, we and others have characterized a plethora of tumor suppressor genes whose expression is aberrantly inhibited by EZH2 in aggressive PCa. However, it remains unclear to us how EZH2 is recruited to the promoters of these important safe-keeping genes in the first place, which represents a major knowledge gap in the field. In the present study, we hypothesized that EZH2 is recruited to the target promoters, at least in part, by another enzyme called G9a, which catalyzes histone H3 lysine 9 methylation, through a mammalian-specific scaffold protein C10orf12 and that G9a and C10orf12 play important roles in driving PCa progression and are potential prognostic biomarkers and therapeutic targets. This hypothesis is supported by our preliminary observation that (1) C10orf12 expression is required for the interaction between the EZH2 and G9a proteins; (2) all three proteins are remarkably upregulated in CRPC, suggesting the presence of an active C10orf12-G9a-EZH2 complex in these cells; and (3) C10orf12 functionally mimics that of EZH2 in terms of promoting cell cycle entry, cell proliferation, and colony formation. To test our hypothesis, in Aim 1 we will first determine how C10orf12 mediates G9a and EZH2 protein interaction and genomic co-localization at target gene promoters in PCa cells. Subsequently, we will investigate whether and how G9a controls EZH2 recruitment to these regions. Aim 2 will focus on defining the oncogenic roles of C10orf12 and G9a in prostate cancer, which have not been previously characterized. We will examine how knockdown or CRISPR-Cas9-mediated knockout of C10orf12 or G9a inhibit oncogenic properties of PCa cells in vitro and abolishes xenograft tumor growth in vivo and how their overexpression conversely drives PCa tumorigenesis. Aim 3 will translate our findings to the clinic by evaluating the potential of C10orf12 and G9a as prognostic biomarkers utilizing a large cohort of PCa tissues with clinical follow-up information and testing the therapeutic effects of several G9a inhibitors in inhibiting PCa growth in vitro and xenograft tumor growth and metastasis in vivo. Ultimate Applicability of the Research: Our study is transformative to the field as it will for the first time characterize novel interactor proteins of EZH2 in PCa cells that may be important in defining its recruitment to the chromatin, an important knowledge gap in the studies of EZH2 biology. We will develop C10orf12 and G9a as novel tissue biomarkers to predict PCa prognosis, which might provide valuable information to early-stage PCa patients regarding the aggressiveness of their disease and help them choose the most appropriate treatments, such as active surveillance versus surgery or radiation treatment. Another major goal of this project is to examine C10orf12 and G9a as new therapeutic targets and to evaluate the efficacy of G9a inhibitors, alone or in combination with EZH2 i
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 29, 2018
- Source ID
- W81XWH1710578
Entities
People
- Jindan Yu
Organizations
- Northwestern University
- United States Army