DNA methylation of E-cadherin is a priming mechanism for prostate development

Abstract

In prostate and other epithelial cancers, E-cadherin (CDH1) is downregulated inappropriately by DNA methylation to promote an invasive phenotype. Though cancer frequently involves a reawakening of developmental signaling pathways, whether DNA methylation of Cdh1 occurs during organogenesis has not been determined. Here we show that DNA methylation of Cdh1 mediates outgrowth of developing prostate ducts. During the three-day gestational window leading up to and including prostate ductal initiation, Cdh1 promoter methylation increases and its mRNA and protein abundance decreases in epithelium giving rise to prostatic buds. DNA methylation is required for prostate specification, ductal outgrowth, and branching morphogenesis. All three endpoints are impaired by a DNA methylation inhibitor, which also decreases Cdh1 promoter methylation and increases Cdh1 mRNA and protein abundance. A CDH1 function-blocking antibody restores prostatic identity, bud outgrowth, and potentiates epithelial differentiation in the presence of the DNA methylation inhibitor. This is the first study to mechanistically link acquired changes in DNA methylation to the normal process of prostate organogenesis. We propose a novel mechanism whereby Cdh1 promoter methylation restricts Cdh1 abundance in developing prostate epithelium to create a permissive environment for prostatic bud outgrowth. Thus, DNA methylation primes the prostate primordium to respond to developmental cues mediating outgrowth, differentiation and maturation of the ductal network.

Androgen receptor DNA methylation regulates the timing and androgen sensitivity of mouse prostate ductal development

“…Female UGS explants grown in the presence of 5AzadC during the first two days of a seven day culture period also formed a greater number of buds compared to controls (Supplemental Figure 1A–B) and formed a similar number of buds compared to male UGSs grown in the presence of 5AzadC during the first two days of a seven day culture period (Supplemental Figure 1C). Both male and female UGSs grown in the presence of 5AzadC during the first two days of a seven day culture have similar histology (Supplemental Figure 1D) and appear to have shorter buds compared to control UGSs, a phenotype consistent with that previously reported (24). Together these results are consistent with DNA methylation functioning as a general mechanism to refine androgen dependent prostatic development by restricting the number of prostatic buds formed.…”

“…Male UGSs already exhibit androgen-induced gene expression at 14dpc (12). To ensure that UGSs used in this experiment were naïve to high androgen levels prior to the culture period, we used female UGSs, which also form prostatic buds in response to androgens (24, 29). Female UGSs were grown for two days in medium containing 5AzadC (5µM) or vehicle alone, followed by five additional days in medium containing androgen alone.…”

“…While 5AzadC is capable of inhibiting DNA methylation across the genome, other studies using this drug reveal its scope of action on gene expression is surprisingly narrow - often involving only a few hundred genes (35). We previously used 5AzadC as a chemical probe to demonstrate a crucial role for E-cadherin DNA methylation in prostatic bud outgrowth (24). Here, using the same approach but modifying the timing of 5AzadC exposure, we revealed a second prostate development phenotype linked to DNA methylation – the timing and scope of prostatic bud formation.…”

“…MeDIP was conducted as described previously (24). UGS explants were pooled (5–6 tissues/pool) and each experimental group consisted of five pools.…”

Role of Epithelial Mesenchymal Transition in Prostate Tumorigenesis

“…The classical epithelial marker E-cadherin is often found to be silenced in PCa due to promoter methylation [85–86]. It is intriguing to note that methylation of E-cadherin is a priming event that helps in creating a permissive environment for outgrowth and continued morphogenesis of prostatic ducts at different stages of the development [87]. This again tells us how PCa cells hijack this evolutionary conserved process to decrease the expression of E-cadherin.…”