The Inhibitory Effect of Sulforaphane on Bladder Cancer Cell Depends on GSH Depletion-Induced by Nrf2 Translocation

Canxia He,Maria Fernanda Taviano,Luigina P Buongiorno,Wei Wang,Natalizia Miceli,Yujuan Shan,Yongping Bao,Jonathan C Y Tang

doi:10.3390/molecules26164919

Abstract

Sulforaphane (SFN), an isothiocyanate (ITCs) derived from glucosinolate that is found in cruciferous vegetables, has been reported to exert a promising anticancer effect in a substantial amount of scientific research. However, epidemical studies showed inconsistencies between cruciferous vegetable intake and bladder cancer risk. In this study, human bladder cancer T24 cells were used as in vitro model for revealing the inhibitory effect and its potential mechanism of SFN on cell growth. Here, a low dose of SFN (2.5 µM) was shown to promote cell proliferation (5.18–11.84%) and migration in T24 cells, whilst high doses of SFN (>10 µM) inhibited cell growth significantly. The induction effect of SFN on nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression at both low (2.5 µM) and high dose (10 µM) was characterized by a bell-shaped curve. Nrf2 and glutathione (GSH) might be the underlying mechanism in the effect of SFN on T24 cell growth since Nrf2 siRNA and GSH-depleting agent L-Buthionine-sulfoximine abolished the effect of SFN on cell proliferation. In summary, the inhibitory effect of SFN on bladder cancer cell growth and migration is highly dependent on Nrf2-mediated GSH depletion and following production. These findings suggested that a higher dose of SFN is required for the prevention and treatment of bladder cancer.

Highlights

Bladder cancer (BC) is the ninth most common cancer worldwide, with an estimated550,000 new cases and 200,000 deaths in 2018, and the incidence of this disease increases with age [1]
Our results suggested that the inhibitory effect of SFN on cell proliferation and migration is highly dependent on the level of GSH depletion and the following production by nuclear factor (erythroid-derived 2)-like 2 (Nrf2) translocation
Given that SFN is capable of stimulating GSH synthesis in T24 cells, we tested whether the mechanism involved was dependent on γ-GCS induction; a key enzyme in glutathione biosynthesis regulated at the transcriptional level by Nrf2

Summary

Introduction

Bladder cancer (BC) is the ninth most common cancer worldwide, with an estimated. 550,000 new cases and 200,000 deaths in 2018, and the incidence of this disease increases with age [1]. Results from a meta-analysis of prospective cohort studies of 14 cohorts with 17 studies including 9447 cases suggested that there was no correlation between cruciferous vegetable intake and bladder cancer risk [9]. Despite mixed outcomes from epidemiologic studies, reports from animal studies have confirmed that SFN or SFN-containing broccoli sprout extract inhibit carcinogenesis, cancer development and/or progression in a wide variety of organs, including breast, colon, liver, stomach, prostate, and especially bladder [10,11,12,13,14,15,16] Our previous results, both in vitro and in vivo, have confirmed the inhibitory effect of SFN on bladder cancer [14,17,18,19]. Our results suggested that the inhibitory effect of SFN on cell proliferation and migration is highly dependent on the level of GSH depletion and the following production by Nrf translocation

Effect of SFN on Cell Growth and Migration in T24 Cells

Effect of γ-GCS on SFN-Induced GSH Increase

Cell Viability Assay

Cell Migration Assay

Knockdown Gene by siRNA

Statistical Analysis