Epigenetics Reactivation of Nrf2 in Prostate TRAMP C1 Cells by Curcumin Analogue FN1

Abstract

It has previously been demonstrated that curcumin is effective against prostate cancer growth and progression in TRAMP mice, potentially acting through the epigenetic modification of the Nrf2 gene and the subsequent induction of the Nrf2-mediated anti-oxidative stress cellular defense pathway. FN1 is a synthetic curcumin analog that shows stronger anti-cancer activity than curcumin. The purpose of this study was to investigate a potential epigenetic effect of FN1 that restores Nrf2 gene expression in TRAMP-C1 cells. Stably transfected HepG2-C8 cells were used to investigate the effect of FN1 on the Nrf2-ARE pathway. Real-time quantitative PCR and western blotting were used to study the influence of FN1 on endogenous Nrf2 and its downstream genes. Bisulfite genomic sequencing (BGS) and methylated DNA immunoprecipitation (MeDIP) were then performed to examine the methylation profile of the Nrf2 promoter. An anchorage-independent colony-formation assay was conducted to test the tumor inhibitory effect of FN1. Epigenetic modification enzymes, including DNMTs and HDACs, were investigated by western blotting. Luciferase reporter assay indicated FN1 was more potent than curcumin in activating the Nrf2-ARE pathway. FN1 increased the mRNA and protein expression of Nrf2 and downstream genes, such as HO-1, NQO1, and UGT1A1. FN1 significantly inhibited the colony formation of TRAMP-C1 cells. BGS and MeDIP assays revealed that FN1 treatment (250 nM for 3 days) decreased the level of CpG methylation of the Nrf2 promoter. FN1 also downregulated epigenetic modification enzymes. In conclusion, our results suggest that FN1 is a novel anti-cancer agent for prostate cancer. FN1 can activate the Nrf2-ARE pathway, inhibit the colony formation of TRAMP-C1 cells and increase the expression of Nrf2 and downstream genes potentially through the decreased expression of keap1 coupled with CpG demethylation of the Nrf2 promoter. This CpG demethylation effect may come from decreased epigenetic modification enzymes, such as DNMT1, DNMT3a, DNMT3b and HDAC4.

Nuclear transcription factor Nrf2 suppresses prostate cancer cells growth and migration through upregulating ferroportin

“…Not surprisingly, previous studies also proved that Nrf2 plays a key role in the development of cancers [28–30], including prostate cancer [19, 31]. It seems that an increased expression of Nrf2 may suppress the proliferation and invasion abilities of prostate cancer cells [19, 32], which exactly agreed with the results of our present study. However, Raatikainen et al revealed that when the Nrf2 was increased, the biochemical recurrence-free survival would be shortened and the overall survival rate would be worse, indicating a worse prognosis of prostate cancer patients and enhanced proliferative and invasive abilities [33].…”

A Subpopulation of the K562 Cells Are Killed by Curcumin Treatment after G2/M Arrest and Mitotic Catastrophe

“…It has been shown to inhibit cell proliferation, cell survival and the production of several cytokines by altering the function of numerous important regulatory pathways, such as NFκB [21] and the transcription factor NRF2 Keap1 [22]. Moreover, Curcumin targets several different proteins and inhibit the activity of various kinases in vitro [23], as well as the activity of histone acetyl transferases [24], therefore, curcumin alters different signaling pathways and also effects epigenetic control of gene expression [25].…”

Protection against oxidative stress mediated by the Nrf2/Keap1 axis is impaired in Primary Biliary Cholangitis

“…Consequently, Nrf2 accumulates, and then, translocates to the nucleus, where it targets a cis-acting antioxidant response element, which activates a set of genes. In addition to p62, the Nrf2/Keap1 signalling axis is regulated by epigenetic mechanisms that involve microRNAs1819. To date, numerous microRNAs have been identified that function as modulators of Nrf2 and related regulatory proteins2021.…”