Modulation of nuclear factor-kappa B activation by the endoplasmic reticulum stress sensor PERK to mediate estrogen-induced apoptosis in breast cancer cells

Abstract

Stress responses are critical for estrogen (E2)-induced apoptosis in E2-deprived breast cancer cells. Nuclear factor-kappa B (NF-κB) is an important therapeutic target to prevent stress responses in chronic inflammatory diseases including cancer. However, whether E2 activates NF-κB to participate in stress-associated apoptosis in E2-deprived breast cancer cells is unknown. Here, we demonstrated that E2 differentially modulates NF-κB activity according to treatment time. E2 initially has significant potential to suppress NF-κB activation; it completely blocks tumor necrosis factor alpha (TNFα)-induced activation of NF-κB. We found that E2 preferentially and constantly enhances the expression of the adipogenic transcription factor CCAAT/enhancer binding protein beta (C/EBPβ), which is responsible for the suppression of NF-κB activation by E2 in MCF-7:5C cells. Interestingly, NF-κB p65 DNA-binding activity is increased when E2 is administered for 48 h, leading to the induction of TNFα and associated apoptosis. Blocking the nuclear translocation of NF-κB can completely prevent the induction of TNFα and apoptosis induced by E2. Further examination revealed that protein kinase RNA-like endoplasmic reticulum kinase (PERK), a stress sensor of unfolded protein response (UPR), plays an essential role in the late activation of NF-κB by E2. This modulation between PERK and NF-κB is mainly mediated by a stress responsive transcription factor, transducer and activator of transcription 3 (STAT3), independently of the classic canonical IκBα signaling pathway. Thus, inhibition of PERK kinase activity completely blocks the DNA binding of both STAT3 and NF-κB, thereby preventing induction of NF-κB-dependent genes and E2-induced apoptosis. All of these findings suggest that PERK is a key regulator to convey stress signals from the endoplasmic reticulum to the nucleus and illustrate a crucial role for the novel PERK/STAT3/NF-κB/TNFα axis in E2-induced apoptosis in E2-deprived breast cancer cells.

1,25-hydroxyvitamin D3 decreases endoplasmic reticulum stress-induced inflammatory response in mammary epithelial cells

“…In addition, MCF-7 cells like normal MECs are VDR positive cells and exposure to 1,25D 3 causes a marked induction of CYP24A1 and several immune response genes [37]. Moreover, cellular stress signaling, such as ER stress-induced activation of the UPR via the ER stress signaling proteins ATF6, IRE1 and PERK and ER stress-mediated activation of NF-κB, occurs largely identical in MCF-7 cells [60,61] like in non-cancer MECs, thus, allowing to use the MCF-7 cell line specifically for studying the potential of 1,25D 3 to modulate ER stress-induced NF-κB-driven inflammatory response in MECs. The present findings show that 1,25D 3 is effective in attenuating ER stress and the NF-κB-driven inflammatory response in MCF-7 cells.…”

Estrogen therapy induces an unfolded protein response to drive cell death in ER+ breast cancer

“…However, preclinical studies to characterize the mechanism(s) underlying therapeutic response to estrogens have thus far been limited to derivatives of two ER+ breast cancer cell lines. Evidence supports mechanisms that include ER-driven upregulation of genes involved in apoptosis, inflammation, and endoplasmic reticulum (EnR) stress Fan et al, 2018;Lewis et al, 2005;Obiorah et al, 2014;Song et al, 2001). We evaluated multiple additional in vivo models of therapeutic response to estrogen and further deciphered a cellular mechanism underlying response to ER reactivation therapy.…”

Suppression of Nuclear Factor-κB by Glucocorticoid Receptor Blocks Estrogen-Induced Apoptosis in Estrogen-Deprived Breast Cancer Cells

“…Our further observations demonstrate that accumulation of stress responses, including endoplasmic reticulum stress, oxidative stress, and inflammatory stress, is a major mechanism by which E 2 induces apoptosis (12,13). Particularly, endoplasmic reticulum is a critical regulatory site for conveying signals between the nucleus and cytoplasm to decide the cell fate (12,14,15). The endoplasmic reticulum stress sensor, protein kinase RNA-like endoplasmic reticulum kinase (PERK) is responsible for homeostasis of unfolded proteins and is also a key driver of E 2 -induced apoptosis (12,14,15).…”

“…Particularly, endoplasmic reticulum is a critical regulatory site for conveying signals between the nucleus and cytoplasm to decide the cell fate (12,14,15). The endoplasmic reticulum stress sensor, protein kinase RNA-like endoplasmic reticulum kinase (PERK) is responsible for homeostasis of unfolded proteins and is also a key driver of E 2 -induced apoptosis (12,14,15). Specifically, PERK links endoplasmic reticulum stress with oxidative stress and increases transcription factor NF-kB DNA-binding activity to induce TNFa in E 2 -deprived breast cancer cells (12,15,16).…”

“…The endoplasmic reticulum stress sensor, protein kinase RNA-like endoplasmic reticulum kinase (PERK) is responsible for homeostasis of unfolded proteins and is also a key driver of E 2 -induced apoptosis (12,14,15). Specifically, PERK links endoplasmic reticulum stress with oxidative stress and increases transcription factor NF-kB DNA-binding activity to induce TNFa in E 2 -deprived breast cancer cells (12,15,16). Our recent findings have demonstrated that the PERK/NF-kB/TNFa axis plays a critical role in E 2 -induced apoptosis (15,16).…”