Sulforaphane Alone and in Combination with Clofarabine Epigenetically Regulates the Expression of DNA Methylation-Silenced Tumour Suppressor Genes in Human Breast Cancer Cells

Abstract

Background/Aim: Sporadic breast cancer is frequently associated with aberrant DNA methylation patterns that are reversible and responsive to environmental factors, including diet. In the present study, we investigated the effects of sulforaphane (SFN), a phytochemical from cruciferous vegetables, on the methylation and expression of PTEN and RARbeta2 tumour suppressor genes as well as on the expression of regulators of DNA methylation reaction, DNMT1, p53, and p21, in MCF-7 and MDA-MB-231 human breast cancer cells with different invasive potential. We also evaluate the role of SFN epigenetic effects in support of therapy with clofarabine (ClF) that was recently shown to modulate the epigenome as well. Methods: Promoter methylation and gene expression were estimated using methylation-sensitive restriction analysis and real-time PCR, respectively. Results: In both MCF-7 and MDA-MB-231 cells, SFN at IC₅₀ (22 and 46 µ<smlcap>M</smlcap>, respectively) and a physiologically relevant 10 µ<smlcap>M</smlcap> concentration lead to hypomethylation of PTEN and RARbeta2 promoters with concomitant gene up-regulation. The combination of SFN and ClF enhances these effects, resulting in an increase in cell growth arrest and apoptosis at a non-invasive breast cancer stage. Conclusions: Our findings provide evidence that SFN activates DNA methylation-silenced tumour suppressor genes in breast cancer cells and may contribute to SFN-mediated support of therapy with an anti-cancer drug, ClF, increasing its applications in solid tumours.

Sulforaphane and Epigallocatechin Gallate Restore Estrogen Receptor Expression by Modulating Epigenetic Events in the Breast Cancer Cell Line MDA-MB-231: A Systematic Review and Meta-Analysis

“…Referring to apoptosis, the authors indicated an increase in apoptosis rate in 4 cases, while in 1 study this effect could not be observed. Two studies analyzed the standard MDA-MB-231 cell line [24,25], while one study [26] analyzed MDA-MB-231 cells both with and without ERα expression. The concentration of SFN, tested in the included studies, was 10 µ M .…”

“…Even though PTEN and RARβ2 encode proteins potentially able to indirectly reduce the level of DNMT1 by downregulating the intracellular oncogenic mitogen-activated protein kinase/activator protein 1 signaling cascade, this hypothesized effect could not be detected in the MDA-MB-231 cell line. No DNMT1 suppression was noticed, while p21 was found to be upregulated through the p53-independent pathway [24]. …”

Dietary antioxidants remodel DNA methylation patterns in chronic disease

“…Earlier gene candidate studies performed in murine RAW 264.7 macrophage cells and TRAMP C1 prostate cancer cells delivered evidence for curcumin-mediated demethylation and activation of Nrf2, a potent activator of antioxidant pathways (Khor et al, 2011). Another member of the antioxidant network, GSTP1, was also found to be demethylated and activated upon exposure of breast cancer cells to curcumin (Kumar, Sharma, & Rathi, 2017 CDKN2A at a non-invasive breast cancer stage , PTEN and RARβ2 in breast cancer cells (Lubecka-Pietruszewska et al, 2015), and RARβ, CDH1, DAPK1, and GSTP1…”

“…Szymczyk, & Fabianowska-Majewska, 2018;Lubecka-Pietruszewska et al, 2015). Demethylation and re-activation of tumour suppressor genes in response to SFN have been reported, for example, for…”

Current potential health benefits of sulforaphane

“…In this present study, we reviewed the most recent studies on the biological and pharmacological activities of SFN (Table 1(Tab. 1)) (References in Table 1: Pal and Konkimalla, 2016[34]; Zhao et al, 2016[55]; Wu et al, 2016[52]; Sasaki et al, 2016[39]; Jiang et al, 2016[17]; Hernández-Rabaza et al, 2016[15]; Sikdar et al, 2016[45]; Li et al, 2016[28]; Thaler et al, 2016[48]; Lan et al, 2016[23]; Shehatou and Suddek, 2016[42]; Townsend and Johnson, 2016[49]; Qi et al, 2016[37]; Abbas et al, 2016[1]; Kikuchi et al, 2015[21]; Atwell et al, 2015[6]; Ma et al, 2015[30]; Kim et al, 2015[22]; Wang et al, 2015[50]; Lubecka-Pietruszewska et al, 2015[29]; Brown et al, 2015[7]; Carrasco-Pozo et al, 2015[8]; Ambrecht et al, 2015[3]; Lavich et al, 2015[24]; Waston et al, 2015[51]; Shirai et al, 2015[43]; Prasad and Mishra, 2015[36]; Li et al, 2015[27]; Cipolla et al, 2015[9]; Angeloni et al, 2015[5]; Oguz et al, 2015[33]; Noh et al, 2015[32]; Shang et al, 2015[41]; Horwacik et al, 2015[16]; Shokeir et al, 2015[44]; Alzoubi et al, 2015[2]; Gabriel et al, 2015[13]; Kee et al, 2015[20]; Rizzo et al, 2014[38]; Pan et al, 2014[35]; Sayed et al, 2014[40]; Singh et al, 2014[46]; Maeda et al, 2014[31]; Zhang et al, 2014[54]; Lee et al, 2014[25]; Fimognari et al, 2014[12]; Jo et al, 2014[18]). …”