Sulforaphane-induced apoptosis involves the type 1 IP3 receptor.

Sona Hudecova,Olga Krizanova,Juraj Kopacek,Marie Novakova,Michal Pastorek,Marta Sirova,Paulina Gronesova,Lucia Csaderova,Eliska Svastova,Michaela Fojtu,Jan Sedlak,Jana Markova,Tibor Stracina,Veronika Simko,Dana Cholujova,Silvia Pastorekova

doi:10.18632/oncotarget.8968

Sulforaphane-induced apoptosis involves the type 1 IP3 receptor.

Sona Hudecova, Olga Krizanova + Show 14 more

Open Access

https://doi.org/10.18632/oncotarget.8968

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Abstract

In this study we show that anti-tumor effect of sulforaphane (SFN) is partially realized through the type 1 inositol 1,4,5-trisphosphate receptor (IP3R1). This effect was verified in vitro on three different stable cell lines and also in vivo on the model of nude mice with developed tumors. Early response (6 hours) of A2780 ovarian carcinoma cells to SFN treatment involves generation of mitochondrial ROS and increased transcription of NRF2 and its downstream regulated genes including heme oxygenase 1, NAD(P)H:quinine oxidoreductase 1, and KLF9. Prolonged SFN treatment (24 hours) upregulated expression of NRF2 and IP3R1. SFN induces a time-dependent phosphorylation wave of HSP27. Use of IP3R inhibitor Xestospongin C (Xest) attenuates both SFN-induced apoptosis and the level of NRF2 protein expression. In addition, Xest partially attenuates anti-tumor effect of SFN in vivo. SFN-induced apoptosis is completely inhibited by silencing of IP3R1 gene but only partially blocked by silencing of NRF2; silencing of IP3R2 and IP3R3 had no effect on these cells. Xest inhibitor does not significantly modify SFN-induced increase in the rapid activity of ARE and AP1 responsive elements. We found that Xest effectively reverses the SFN-dependent increase of nuclear content and decrease of reticular calcium content. In addition, immunofluorescent staining with IP3R1 antibody revealed that SFN treatment induces translocation of IP3R1 to the nucleus. Our results clearly show that IP3R1 is involved in SFN-induced apoptosis through the depletion of reticular calcium and modulation of transcription factors through nuclear calcium up-regulation.

Highlights

Sulforaphane (SFN), a dietary isothiocyanate, is a product of myrosinase enzyme hydrolysis of the natural precursor glucoraphanin that occurs in various cruciferous vegetables, including broccoli, Brussels sprouts and cauliflower [1,2,3]
It was reported that histone H3 Ser-10 phosphorylation occurs when cells are exposed to various death stimuli, suggesting a potential role in the regulation of apoptosis [21]
Our results suggest the involvement of IP3R in the SFN-induced increase of nuclear factor (erythroidderived 2)-like 2 (NRF2) protein and apoptosis similar to what we have found in the A2780 cell line (Figure 4C, 4D)

Summary

Introduction

Sulforaphane (SFN), a dietary isothiocyanate, is a product of myrosinase enzyme hydrolysis of the natural precursor glucoraphanin that occurs in various cruciferous vegetables, including broccoli, Brussels sprouts and cauliflower [1,2,3]. When hepatoma cells are incubated with 100 μM SFN for approximately 30 min, the intracellular concentration reaches approximately 6.4 mM [5]. This gives SFN a potential for therapeutic utilization. Higher concentrations are achieved in tissues and it has been reported that the SFN concentration in the small intestine reached 3 and 13 nmol/g of tissue, which is equivalent to roughly 3–30 μM of total SFN [8]. The plasma levels of isothiocyanates reported so far in www.impactjournals.com/oncotarget the literature (in the μM range, but often

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