NRF2 Induction Supporting Breast Cancer Cell Survival Is Enabled by Oxidative Stress–Induced DPP3–KEAP1 Interaction

Abstract

NRF2 is a transcription factor serving as a master regulator of the expression of many genes involved in cellular responses to oxidative and other stresses. In the absence of stress, NRF2 is constantly synthesized but maintained at low levels as it is targeted by KEAP1 for ubiquitination and proteasome-mediated degradation. NRF2 binds KEAP1 mainly through a conserved “ETGE” motif that has also been found in several other proteins, such as DPP3, which has been shown to bind KEAP1 and enhance NRF2 function upon overexpression. Here we demonstrate the interaction between endogenous DPP3 and endogenous KEAP1. We further show that the DPP3-KEAP1 interaction is strongly induced by hydrogen peroxide and that DPP3 is required for timely NRF2 induction and nuclear accumulation in the estrogen receptor (ER)-positive MCF7 breast cancer cells. Moreover, we present evidence that the binding of DPP3 to KEAP1 stabilizes the latter. Finally, we show that DPP3 is overexpressed in breast cancer and that elevated levels of DPP3 mRNA correlate with increased NRF2 downstream gene expression and poor prognosis, particularly for ER-positive breast cancer. Our studies reveal novel insights into the regulation of NRF2 and identify DPP3 and an NRF2 transcriptional signature as potential biomarkers for breast cancer prognosis and treatment.

Absence of Dipeptidyl Peptidase 3 Increases Oxidative Stress and Causes Bone Loss

“…Nrf2 pathway activation by DPP3 has been clearly shown to be independent of DPP3 enzymatic activity. (30) In this respect, we showed almost complete lack of enzymatic function in vitro in our Dpp3 KO mouse using a standard synthetic substrate, but we did not systematically look for DPP3 substrate in vivo. A series of compounds have been proposed to play this role, mainly through in vitro studies.…”

“…(24) It has been purified from several murine and human biological sources and has been proposed to act in the terminal stages of protein turnover, in the framework of several pathophysiological processes through the hydrolysis of bioactive peptides, (24)(25)(26)(27) in metabolic, cardiovascular, and neoplastic diseases. (25,26,(28)(29)(30) For the first time, here we demonstrate DPP3 protein expression in the bone tissue and uncover its role in bone pathophysiology, taking advantage of our newly generated Dpp3 knockout (KO) mouse model.…”

Transcription Factor NRF2 as a Therapeutic Target for Chronic Diseases: A Systems Medicine Approach

“…The list of all the proteins that interact with NRF2 in the human interactome is available online at http://sbi.imim.es/data/nrf2/. 352 formation underlining colon (Gonzalez-Donquiles et al, 2017) and breast (Lu et al, 2017) tumors.…”

“…Recently, it was shown that dipeptidyl-peptidase 3, which bears an ETGE motif, may compete with NRF2 for binding to KEAP1 (Hast et al, 2013). Overexpression of dipeptidyl-peptidase 3, possibly induced by chronic alteration of the redox status, correlates with increased expression of ARE genes and poor prognosis, particularly in estrogen receptor-positive breast cancer (Lu et al, 2017).…”

The Role of Nrf2 in the Response to Normal Tissue Radiation Injury

“…(12,19, 20)]. In addition to stress-related activation, a number of proteins [e.g., p21 (21), p62, PALB2, IKKB, DPP3 (22) and iASPP (23)] can competitively bind to Keap1 and inhibit Nrf2 ubiquitination. Inactivation of Keap1 allows de novo synthesized Nrf2 to translocate to the nucleus and either transduce or suppress target genes [Supplementary Fig.…”