Resistance to ferroptosis, a form of regulated cell death caused by disruptions in iron ion and intracellular redox homeostasis, is closely related to tumorigenesis and tumor drug resistance; therefore, targeting ferroptosis-related pathways has garnered attention as a potential antitumor therapeutic strategy. However, the molecular mechanisms underlying ferroptosis resistance in tumor cells remain unknown. Zinc-finger estrogen receptor interaction clone 6 (ZER6) consists of two isoforms with distinct N-termini, p52-ZER6 and p71-ZER6. ZER6 is upregulated in tumors and promotes tumorigenic potential; however, whether ZER6 is involved in tumor cell ferroptosis resistance remains unknown. Herein, we identified p52-ZER6 as a novel regulator of tumor cell ferroptosis resistance. p52-ZER6 promotes the transcriptional activity of DAZAP1, an RNA-binding protein. DAZAP1, in turn, enhances the stability of SLC7A11 mRNA by binding to its 3'-UTR region, thereby increasing SLC7A11 expression and cellular glutathione levels. This subsequently reduces lipid peroxide accumulation and enhances tumor cell ferroptosis resistance, eventually promoting tumorigenic potential. These findings reveal a new function of p52-ZER6 in regulating SLC7A11 mRNA stability via DAZAP1, ultimately leading to ferroptosis resistance and tumorigenic potential. Additionally, we also suggest targeting p52-ZER6 as a potential strategy to promote the efficacy of ferroptosis-based antitumor therapies.

Pulmonary hypertension (PH) is a life-threatening disease characterized by pulmonary vascular remodeling, in which hyperproliferation of pulmonary artery smooth muscle cells (PASMCs) plays an important role. The cysteine 674 (C674) in the sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase 2 (SERCA2) is the critical redox regulatory cysteine to regulate SERCA2 activity. Heterozygous SERCA2 C674S knock-in mice (SKI), where one copy of C674 was substituted by serine to represent partial C674 oxidative inactivation, developed significant pulmonary vascular remodeling resembling human PH, and their right ventricular systolic pressure modestly increased with age. In PASMCs, substitution of C674 activated inositol requiring enzyme 1 alpha (IRE1α) and spliced X-box binding protein 1 (XBP1s) pathway, accelerated cell cycle and cell proliferation, which reversed by IRE1α/XBP1s pathway inhibitor 4μ8C. In addition, suppressing the IRE1α/XBP1s pathway prevented pulmonary vascular remodeling caused by substitution of C674. Similar to SERCA2a, SERCA2b is also important to restrict the proliferation of PASMCs. Our study articulates the causal effect of C674 oxidative inactivation on the development of pulmonary vascular remodeling and PH, emphasizing the importance of C674 in restricting PASMC proliferation to maintain pulmonary vascular homeostasis. Moreover, the IRE1α/XBP1s pathway and SERCA2 might be potential targets for PH therapy.

Prolyl-4-hydroxylase domain (PHDs) family is one of the most important regulatory factors in hypoxic stress. PHD2 plays a critical role in cells and tissues adaptation to the low oxygen environment. Its hydroxylation activity regulates the stability and transcriptional activity of the hypoxia-inducible factor 1 (HIF-1), which is the key factor in response to hypoxic stress. Subsequently, PHD2 acts as an important factor in oxygen homeostasis. Studies have shown that PHD2, through its regulation on HIF-1, plays an important role in the post-ischemic neovascularization. Furthermore, under hypoxic condition, PHD2 also regulates other pathways that positively regulate angiogenesis factors HIF-1 independently. Moreover, recently, several evidences have also shown that PHD2 also affects tumor growth and metastasis in a tumor microenvironment. Based on these facts, PHD2 have been considered as a potential therapeutic target both in treating ischemic diseases and tumors. Here, we review the molecular regulation mechanism of PHD2 and its physiological and pathological functions. We focus on the role of PHD2 in both therapeutic angiogenesis for ischemic disease and tumor angiogenesis, and the current progress in utilizing PHD2 as a therapeutic target.
Animals ; Humans ; Hydroxylation ; Hypoxia-Inducible Factor 1 ; metabolism ; Hypoxia-Inducible Factor-Proline Dioxygenases ; antagonists & inhibitors ; physiology ; Neoplasms ; blood supply ; metabolism ; pathology ; therapy ; Neovascularization, Pathologic ; metabolism ; pathology ; Tumor Microenvironment ; Vascular Diseases ; pathology ; therapy

Prolyl-4-hydroxylase domain (PHDs) family is one of the most important regulatory factors in hypoxic stress. PHD2 plays a critical role in cells and tissues adaptation to the low oxygen environment. Its hydroxylation activity regulates the stability and transcriptional activity of the hypoxia-inducible factor 1 (HIF-1), which is the key factor in response to hypoxic stress. Subsequently, PHD2 acts as an important factor in oxygen homeostasis. Studies have shown that PHD2, through its regulation on HIF-1, plays an important role in the post-ischemic neovascularization. Furthermore, under hypoxic condition, PHD2 also regulates other pathways that positively regulate angiogenesis factors HIF-1 independently. Moreover, recently, several evidences have also shown that PHD2 also affects tumor growth and metastasis in a tumor microenvironment. Based on these facts, PHD2 have been considered as a potential therapeutic target both in treating ischemic diseases and tumors. Here, we review the molecular regulation mechanism of PHD2 and its physiological and pathological functions. We focus on the role of PHD2 in both therapeutic angiogenesis for ischemic disease and tumor angiogenesis, and the current progress in utilizing PHD2 as a therapeutic target.