2 The tumor suppressor p53 is the most commonly mutated gene in human cancers, and iron is necessary for 3 cancer cell growth and proliferation, but there is a significant gap in knowledge for how the two affect cellular 4 physiology. The wild-type form of p53 has been shown to both regulate iron homeostasis and itself be 5 regulated in response to iron availability. Wild-type p53 promotes iron sequestration into its storage form, which 6 reduces its availability for cellular proliferation and participation in free radical formation, whereas excess iron 7 can decrease p53 signaling and abate its tumor suppressive functions. Conversely, cells that lack p53, or 8 express a mutant p53, tend to accumulate iron in response to DNA damage, and mutations in p53 have been 9 shown to decrease the responsiveness of tumor cells to iron restriction. Despite the significant evidence for 10 disruption in iron homeostasis following p53 mutation however, the mechanisms controlling iron metabolism in 11 cells with p53 mutations are unknown. The long-term goal of the Montgomery lab is to understand how tumor 12 cells compete for and acquire the exaggerated amounts of iron needed to support neoplastic growth and tumor 13 expansion. The primary objective of this work is to determine how p53 mutation status influences the 14 molecular control of iron homeostasis. The rationale is that understanding how iron metabolism is regulated in 15 cells with distinct p53 mutation types could help predict and improve outcomes for the targeting of mutant p53 16 in cancer therapy. The central hypothesis is that mutant p53-dependent disruptions in iron regulatory 17 signaling pathways result from impaired iron-sulfur cluster biogenesis and iron regulatory protein activity. To 18 test this hypothesis, in Aim 1 we will assess iron-sulfur cluster assembly and iron-sulfur containing protein 19 activity under control, iron deficient, and high iron conditions following the induction of mutant p53 expression. 20 We will also utilize total differential proteomics to concurrently measure changes in mutant p53- and iron- 21 dependent signaling pathways in response to changes in iron availability. As our preliminary data 22 demonstrates that iron regulatory pathways are disrupted by induction of mutant p53 expression, activation of 23 ferroptosis, a form of iron-dependent cell death, may represent a novel pathway for targeting cancer cells 24 harboring mutant p53. Thus, in Aim 2 we will determine the extent to which ferroptosis induction influences 25 iron metabolism and ferroptotic cell death in cells with distinct p53 mutation types. After completion of Aim 2, 26 we also expect to have determined how p53 mutation status influences iron acquisition and accumulation and 27 following ferroptosis activation. As p53 is mutated in nearly half of all human cancers, and iron is necessary for 28 cancer cell growth and proliferation, the studies have implications for a wide range of clinically important 29 cancers. 30 31
The tumor suppressor gene p53 is the most commonly mutated gene in human cancer, but mutations in p53 don?t just result in loss of tumor suppressor function, they can also promote cancer progression by altering cellular iron acquisition and metabolism. The proposed work describes a previously unrecognized type of iron regulation that could be exploited to more effectively target mutant p53. The proposed research is relevant to human health because it is expected to lead to new therapeutic approaches for repressing the oncogenic functions of mutant p53.
