Sulforaphane-N-Acetyl-Cysteine Induces Autophagy Through Activation of ERK1/2 in U87MG and U373MG Cells

Abstract

Background/Aims: Sulforaphane-N-acetyl-cysteine (SFN-NAC) is a sulforaphane (SFN) metabolite with a longer half-life and better blood–brain barrier permeability than those of SFN. Previous studies have found that SFN-NAC can act via ERK to destroy microtubules and inhibit cell growth in lung cancer cells. However, the underlying mechanisms are unclear, and it is unknown whether SFN-NAC can inhibit the growth of glioma. Here, we have demonstrated for the first time that SFN-NAC activates autophagy-mediated downregulation of α-tubulin expression via the ERK pathway. Methods: U87MG and U373MG cells, two widely used glioma cell lines, were utilized in this study. Apoptosis assay, western blot analysis, co-immunoprecipitation, immunostaining, and electron microscopy were used to analyze the effect of SFN-NAC on α-tubulin and its interaction with microtube-associated protein 1 light-chain 3 (LC3). Results: SFN-NAC induced cell-cycle arrest in the G2/M phase and dose-dependently induced intracellular ERK activation, autophagy, and α-tubulin downregulation. These SFN-NAC-induced effects were reversed by inhibiting the ERK pathway with its inhibitor PD98059. U87MG and U373MG cells were transfected with LC3 small interfering RNA, and the subsequent inhibition of autophagy reversed the downregulation of α-tubulin by SFN-NAC. Furthermore, co-immunoprecipitation experiments and confocal microscopy confirmed that SFN-NAC promotes the binding of LC3 with α-tubulin in the cytoplasm. Cell viability experiments demonstrate that SFN-NAC inhibits the growth of U87MG and U373MG cell colonies. Conclusion: These findings suggest that SFN-NAC is a novel potential anti-glioma agent.

Ferroptosis-Related Gene Signature Predicts Glioma Cell Death and Glioma Patient Progression

“…The procedures for Western blot were described in detail in a previous study (Liu H. J. et al, 2018). In the current study, after incubation with primary antibodies, the HRP labeled anti-rabbit or anti-mouse secondary antibody was used for incubation at room temperature for another period of 1 h. Specific protein bands were detected using an ECL Western blotting kit, following the recommended procedure.…”

The Role of Isothiocyanates as Cancer Chemo-Preventive, Chemo-Therapeutic and Anti-Melanoma Agents

“…ITCs can act as autophagic inducers and, by doing so, they may exert either a protective role [148,149,150,151,152,153,154,155,156,157] or promote cell death [158,159,160,161,162] according to tumour type, stage and genetic context. To this end, a recent study investigated the autophagic involvement on BITC-induced inhibition of cell growth in lung cancer cells and showed an induction of ER (endoplasmatic reticulum) stress-mediated autophagy capable of protecting from the suppressive effects of BITC on cancer cell growth.…”

“…In this experimental setting, the apoptotic induction was attenuated after pharmacological inhibition of autophagy [159]. In line, SFN-NAC (sulforaphane-N-acetyl-cysteine), an important metabolite of SFN, was shown to downregulate α-tubulin through induction of autophagy and activation of ERK1/2, leading to cell-cycle arrest and cell growth inhibition in glioma cells [160].…”

Sulforaphane Causes Cell Cycle Arrest and Apoptosis in Human Glioblastoma U87MG and U373MG Cell Lines under Hypoxic Conditions

“…Transient phosphorylation of ERK1/2 (5-15-min stimulation) promotes cell growth [60], while sustained phosphorylation of ERK1/2 (>15 min stimulation) is responsible for cell apoptosis [61]. In recent studies, SFN significantly increased the phosphorylation of ERK1/2 in different cancer cell lines [62], which is closely related to cell division, invasion, and apoptosis [63,64]. Accordingly, in human GBM U87MG and U373MG cells, SFN inhibited invasion by activating ERK1/2 signaling.…”