Breast cancer tumorigenicity is dependent on high expression levels of NAF-1 and the lability of its Fe-S clusters

Abstract

Iron-sulfur (Fe-S) proteins are thought to play an important role in cancer cells mediating redox reactions, DNA replication, and telomere maintenance. Nutrient-deprivation autophagy factor-1 (NAF-1) is a 2Fe-2S protein associated with the progression of multiple cancer types. It is unique among Fe-S proteins because of its 3Cys-1His cluster coordination structure that allows it to be relatively stable, as well as to transfer its clusters to apo-acceptor proteins. Here, we report that overexpression of NAF-1 in xenograft breast cancer tumors results in a dramatic augmentation in tumor size and aggressiveness and that NAF-1 overexpression enhances the tolerance of cancer cells to oxidative stress. Remarkably, overexpression of a NAF-1 mutant with a single point mutation that stabilizes the NAF-1 cluster, NAF-1(H114C), in xenograft breast cancer tumors results in a dramatic decrease in tumor size that is accompanied by enhanced mitochondrial iron and reactive oxygen accumulation and reduced cellular tolerance to oxidative stress. Furthermore, treating breast cancer cells with pioglitazone that stabilizes the 3Cys-1His cluster of NAF-1 results in a similar effect on mitochondrial iron and reactive oxygen species accumulation. Taken together, our findings point to a key role for the unique 3Cys-1His cluster of NAF-1 in promoting rapid tumor growth through cellular resistance to oxidative stress. Cluster transfer reactions mediated by the overexpressed NAF-1 protein are therefore critical for inducing oxidative stress tolerance in cancer cells, leading to rapid tumor growth, and drugs that stabilize the NAF-1 cluster could be used as part of a treatment strategy for cancers that display high NAF-1 expression.Fe-S | ROS | NEET | cancer | NAF-1

Structure of the human monomeric NEET protein MiNT and its role in regulating iron and reactive oxygen species in cancer cells

“…Biological studies confirmed our initial proposals and led to the hypothesis that the NEETs participate in the regulation of different iron, Fe-S, and reactive oxygen/redox reactions in cells (2,13). Indeed, NEET proteins play a key role in many cellular functions, as well as in different human diseases (2,6,(13)(14)(15)(16)(17)(18).…”

“…Also known as CDGSH proteins, due to their signature [2Fe-2S]-binding domain consensus sequence [C-X-C-X2-(S/T)-X3-P-X-C-D-G-(S/A/T)-H], these proteins are highly conserved from bacteria to humans (3). The 3Cys-1His cluster-binding site of NEET proteins houses a [2Fe-2S] redox-sensing cluster that can be transferred to apo-acceptor protein(s) when the cluster is oxidized (2,(4)(5)(6)(7). The [2Fe-2S] clusters of NEET proteins can also participate in electron transfer reactions (8)(9)(10)(11).…”

Expression of a dominant‐negative AtNEET‐H89C protein disrupts iron–sulfur metabolism and iron homeostasis in Arabidopsis

“…Although AtNEET was found to be localized to the chloroplast (Nechushtai et al , ; Su et al , ), and the suppression of its expression was shown to cause impaired growth, early senescence, and the accumulation of Fe and ROS in Arabidopsis plants (Nechushtai et al , ), the function of AtNEET in relation to its localization and the phenotypes its suppression induced were unclear. Here we show that disrupting AtNEET function using a dominant‐negative strategy (Darash‐Yahana et al , ) impairs chloroplastic 2Fe–2S metabolism and causes the enhanced expression of many different transcripts involved in Fe‐deficiency responses, Fe–S biosynthesis in mitochondria, cytosol and chloroplasts, and Fe–S proteins (Figures and ). Proteomics analysis shows that despite the higher expression levels of transcripts encoding Fe–S proteins, the abundance of several Fe–S proteins, and in particular 2Fe–2S, in H89C plants is low (e.g.…”

Comparative proteomic profiling reveals a role for Cisd2 in skeletal muscle aging

“…By way of contrast, only the Cisd2 mKO mice showed significant mitochondrial dysfunction. Furthermore, previous studies have revealed that Cisd2‐deficient mouse embryonic fibroblasts (MEFs) exhibit increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) (Wiley et al., 2013), and that Cisd2 overexpression is able to protect cells from H 2 O 2 ‐induced oxidative stress and cell death using a breast cancer cell model (Darash‐Yahana et al., 2016). In this context, four DEPs that are related to the ROS response and redox regulation were pinpointed; these are involved in the “NRF2‐mediated oxidative stress response” and “glutathione redox reactions” pathways.…”