CYP2J2produced epoxyeicosatrienoic acids contribute to the ferroptosis resistance of pancreatic ductal adenocarcinoma in a PPARdependent manner

A new perspective: Acyl-CoA synthetase long-chain family member 4 inhibits ubiquitin-specific protease 7-induced epithelial ovarian cancer progression by inducing ferroptosis and M1 macrophage polarization

Objective

Epithelial ovarian cancer (EOC) is the most common and lethal type of ovarian cancer, and the cross-talk between tumor cell ferroptosis and macrophages is essential to cancer progression. This study aims to investigate the roles of ubiquitin-specific protease 7 (USP7) and acyl-CoA synthetase long-chain family member 4 (ACSL4) in the pathogenesis of EOC.

Material and Methods

The expression patterns of USP7 and ACSL4 in EOC cell lines were first determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot. ACSL4 recombinant protein was applied alone or in conjunction with a USP7 overexpression plasmid in EOC cells, and the effects of USP7 and ACSL4 on EOC cell proliferation and apoptosis were assessed using colony formation assays and terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling staining. The effects of USP7 and ACSL4 on ferroptosis in EOC cells were evaluated by measuring reactive oxygen species (ROS) fluorescence intensity, malondialdehyde (MDA), glutathione (GSH) levels, and glutathione peroxidase 4 (GPX4) messenger RNA (mRNA) levels. Co-culture of EOC cell-conditioned medium treated with ACSL4 recombinant protein or USP7 overexpression plasmid was performed with Human Acute Monocytic Leukemia Cell Line (THP-1) macrophages, and the expression levels of cluster of differentiation 86 and cluster of differentiation 206 were analyzed by flow cytometry. The expression levels of M1 polarization markers and M2 markers in macrophages were measured by qRT-PCR.

Results

ACSL4 was expressed at low levels in the EOC cell lines, whereas USP7 was expressed at high levels. Treatment with ACSL4 recombinant protein reduced colony formation and increased apoptotic cell levels in the EOC cells (P < 0.001). In addition, ACSL4 treatment increased ROS fluorescence intensity and MDA levels while decreasing GSH levels and GPX4 expression (P < 0.001). Furthermore, ACSL4 treatment promoted the polarization of THP-1 macrophages toward M1, increasing the expression of M1 markers (P < 0.001). USP7 overexpression exerted the opposite effect (P < 0.001).

Conclusion

This study reveals the critical role of USP7 in the progression of EOC. ACSL4 inhibits EOC growth and anti-apoptosis by inhibiting USP7-induced antiferroptosis and anti-M1 macrophage polarization, highlighting this mechanism as a potential therapeutic target in EOC.

Ferroptosis in thyroid cancer: mechanisms, current status, and treatment

Thyroid cancer (TC) represents the most prevalent malignancy within the endocrine system. In recent years, there has been a marked global increase in the incidence of thyroid cancer, garnering substantial scientific interest. Comprehensive investigations into the pathogenesis of TC have identified a significant association with ferroptosis, a newly characterized form of cell death mediated by iron ions. Distinct from apoptosis, necrosis, and autophagy, ferroptosis is characterized by the accumulation of lipid peroxides and reactive oxygen species, culminating in cellular damage and death.Recent research has elucidated a connection between ferroptosis and the initiation, progression, and treatment of thyroid cancer. These findings underscore the significance of ferroptosis in thyroid cancer and offer valuable insights into the development of novel therapeutic strategies and precise predictive markers. The unique mechanisms of ferroptosis present opportunities for targeting treatment-resistant thyroid cancers. Consequently, the regulation of ferroptosis may emerge as a novel therapeutic target, potentially addressing the limitations of current treatments. Moreover, elucidating the molecular mechanisms underpinning ferroptosis in thyroid cancer may facilitate the identification of novel biomarkers for early detection and prognostication. This review endeavors to synthesize the extant knowledge regarding the role of ferroptosis in thyroid cancer, examine potential therapeutic implications, and propose future research trajectories to enhance the understanding and clinical application of ferroptosis.

FSP1-mediated ferroptosis in cancer: from mechanisms to therapeutic applications

Ferroptosis is a new discovered regulated cell death triggered by the ferrous ion (Fe2+)-dependent accumulation of lipid peroxides associated with cancer and many other diseases. The mechanism of ferroptosis includes oxidation systems (such as enzymatic oxidation and free radical oxidation) and antioxidant systems (such as GSH/GPX4, CoQ10/FSP1, BH4/GCH1 and VKORC1L1/VK). Among them, ferroptosis suppressor protein 1 (FSP1), as a crucial regulatory factor in the antioxidant system, has shown a crucial role in ferroptosis. FSP1 has been well validated to ferroptosis in three ways, and a variety of intracellular factors and drug molecules can alleviate ferroptosis via FSP1, which has been demonstrated to alter the sensitivity and effectiveness of cancer therapies, including chemotherapy, radiotherapy, targeted therapy and immunotherapy. This review aims to provide important frameworks that, bring the regulation of FSP1 mediated ferroptosis into cancer therapies on the basis of existing studies.

PPARα alleviates iron overload-induced ferroptosis in mouse liver

Ferroptosis is an iron-dependent form of non-apoptotic cell death implicated in liver, brain, kidney, and heart pathology. How ferroptosis is regulated remains poorly understood. Here, we show that PPARα suppresses ferroptosis by promoting the expression of glutathione peroxidase 4 (Gpx4) and by inhibiting the expression of the plasma iron carrier TRF. PPARα directly induces Gpx4 expression by binding to a PPRE element within intron 3. PPARα knockout mice develop more severe iron accumulation and ferroptosis in the liver when fed a high-iron diet than wild-type mice. Ferrous iron (Fe2+ ) triggers ferroptosis via Fenton reactions and ROS accumulation. We further find that a rhodamine-based "turn-on" fluorescent probe(probe1) is suitable for the in vivo detection of Fe2+ . Probe1 displays high selectivity towards Fe2+ , and exhibits a stable response for Fe2+ with a concentration of 20 μM in tissue. Our data thus show that PPARα activation alleviates iron overload-induced ferroptosis in mouse livers through Gpx4 and TRF, suggesting that PPARα may be a promising therapeutic target for drug discovery in ferroptosis-related tissue injuries. Moreover, we identified a fluorescent probe that specifically labels ferrous ions and can be used to monitor Fe2+ in vivo.

[Fatty acid epoxides in the regulation of the inflammation]

Cyclooxygenase and lipoxygenase derived lipid metabolites of polyunsaturated fatty acids (PUFAs), as well as their role in the inflammation, have been studied quite thoroughly. However, cytochrome P450 derived lipid mediators, as well as their participation in the regulation of the inflammation, need deeper understanding. In recent years, it has become known that PUFAs are oxidized by cytochrome P450 epoxygenases to epoxy fatty acids, which act as the extremely powerful lipid mediators involved in resolving inflammation. Recent studies have shown that the anti-inflammatory mechanisms of ω-3 PUFAs are also mediated by their conversion to the endocannabinoid epoxides. Thus, it is clear that a number of therapeutically relevant functions of PUFAs are due to their conversion to PUFA epoxides. However, with the participation of cytochrome P450 epoxygenases, not only PUFA epoxides, but also other metabolites are formed. They are further are converted by epoxide hydrolases into pro-inflammatory dihydroxy fatty acids and anti-inflammatory dihydroxyeicosatrienoic acids. The study of the role of PUFA epoxides in the regulation of the inflammation and pharmacological modeling of the activity of epoxide hydrolases are the promising strategies for the treatment of the inflammatory diseases. This review systematizes the current literature data of the fatty acid epoxides, in particular, the endocannabinoid epoxides. Their role in the regulation of inflammation is discussed.

Exosomes and ferroptosis: roles in tumour regulation and new cancer therapies

Research on the biological role of exosomes is rapidly developing, and recent evidence suggests that exosomal effects involve ferroptosis. Exosomes derived from different tissues inhibit ferroptosis, which increases tumour cell chemoresistance. Therefore, exosome-mediated regulation of ferroptosis may be leveraged to design anticancer drugs. This review discusses three pathways of exosome-mediated inhibition of ferroptosis: (1) the Fenton reaction; (2) the ferroptosis defence system, including the Xc-GSH-GPX4 axis and the FSP1/CoQ₁₀/NAD(P)H axis; and (3) lipid peroxidation. We also summarize three recent approaches for combining exosomes and ferroptosis in oncology therapy: (1) promoting exosome-inhibited ferroptosis to enhance chemotherapy; (2) encapsulating exosomes with ferroptosis inducers to inhibit cancers; and (3) developing therapies that combine exosomal inhibitors and ferroptosis inducers. This review will contribute toward establishing effective cancer therapies.

Tumor Microenvironment Features and Chemoresistance in Pancreatic Ductal Adenocarcinoma: Insights into Targeting Physicochemical Barriers and Metabolism as Therapeutic Approaches

Currently, the median overall survival of PDAC patients rarely exceeds 1 year and has an overall 5-year survival rate of about 9%. These numbers are anticipated to worsen in the future due to the lack of understanding of the factors involved in its strong chemoresistance. Chemotherapy remains the only treatment option for most PDAC patients; however, the available therapeutic strategies are insufficient. The factors involved in chemoresistance include the development of a desmoplastic stroma which reprograms cellular metabolism, and both contribute to an impaired response to therapy. PDAC stroma is composed of immune cells, endothelial cells, and cancer-associated fibroblasts embedded in a prominent, dense extracellular matrix associated with areas of hypoxia and acidic extracellular pH. While multiple gene mutations are involved in PDAC initiation, this desmoplastic stroma plays an important role in driving progression, metastasis, and chemoresistance. Elucidating the mechanisms underlying PDAC resistance are a prerequisite for designing novel approaches to increase patient survival. In this review, we provide an overview of the stromal features and how they contribute to the chemoresistance in PDAC treatment. By highlighting new paradigms in the role of the stromal compartment in PDAC therapy, we hope to stimulate new concepts aimed at improving patient outcomes.