Efficient iron utilization compensates for loss of extracellular matrix of ovarian cancer spheroids

Synergistic suppression of ovarian cancer by combining NRF2 and GPX4 inhibitors: in vitro and in vivo evidence

Ovarian cancer is a significant challenge in women's health due to the lack of effective screening and diagnostic methods, often leading to late detection and the highest mortality rate among all gynecologic tumors worldwide. Recent research has shown that ovarian cancer has an "iron addiction" phenotype which makes it vulnerable to ferroptosis inducers. We tested the combination of NRF2-targeted inhibitors with GPX4-targeted inhibitors in ovarian cancer through in vitro and in vivo experiment. The data showed that combination treatment effectively suppressed adherent cell growth, inhibited suspended cell spheroid formation, and restrained the ability of spheroid formation in 3D-culture. Mechanistically, the combination induced accumulation of ROS, 4-HNE, as well as activation of caspase-3 which indicates that this combination simultaneously increases cell ferroptosis and apoptosis. Notably, inhibition of GPX4 or NRF2 can suppress ovarian cancer spreading and growth in the peritoneal cavity of mice, while the combination of NRF2 inhibitor ML385 with GPX4 inhibitors showed a significant synergistic effect compared to individual drug treatment in a syngeneic mouse ovarian cancer model. Overall, these findings suggest that combining NRF2 inhibitors with GPX4 inhibitors results in a synergy suppression of ovarian cancer in vitro and in vivo, and maybe a promising therapeutic strategy for the treatment of ovarian cancer.

Glycine recalibrates iron homeostasis of lens epithelial cells by blocking lysosome-dependent ferritin degradation

One of the major pathological processes in cataracts has been identified as ferroptosis. However, studies on the iron metabolism mechanism in lens epithelial cells (LECs) and the methods of effectively alleviating ferroptosis in LECs are scarce. Along these lines, we found that in the ultraviolet radiation b (UVB) induced cataract model in vitro and in vivo, the ferritin of LECs is over-degraded by lysosomes, resulting in the occurrence of iron homeostasis disorder. Glycine can affect the ferritin degradation through the proton-coupled amino acid transporter (PAT1) on the lysosome membrane, further upregulating the content of nuclear factor erythrocyte 2 related factor 2 (Nrf2) to reduce the damage of LECs from two aspects of regulating iron homeostasis and alleviating oxidative stress. By co-staining, we further demonstrate that there is a more sensitive poly-(rC)-binding protein 2 (PCBP2) transportation of iron ions in LECs after UVB irradiation. Additionally, this study illustrated the increased expression of nuclear receptor coactivator 4 (NCOA4) in NRF2-KO mice, indicating that Nrf2 may affect ferritin degradation by decreasing the expression of NCOA4. Collectively, glycine can effectively regulate cellular iron homeostasis by synergistically affecting the lysosome-dependent ferritin degradation and PCBP2-mediated ferrous ion transportation, ultimately delaying the development of cataracts.

Iron affects the sphere-forming ability of ovarian cancer cells in non-adherent culture conditions

Introduction: Detachment from the extracellular matrix (ECM) is the first step of the metastatic cascade. It is a regulated process involving interaction between tumor cells and tumor microenvironment (TME). Iron is a key micronutrient within the TME. Here, we explored the role of iron in the ability of ovarian cancer cells to successfully detach from the ECM. Methods: HEY and PEO1 ovarian cancer cells were grown in 3D conditions. To mimic an iron rich TME, culture media were supplemented with 100 μM Fe3+. Cell mortality was evaluated by cytofluorimetric assay. The invasive potential of tumor spheroids was performed in Matrigel and documented with images and time-lapses. Iron metabolism was assessed by analyzing the expression of CD71 and FtH1, and by quantifying the intracellular labile iron pool (LIP) through Calcein-AM cytofluorimetric assay. Ferroptosis was assessed by quantifying mitochondrial reactive oxygen species (ROS) and lipid peroxidation through MitoSOX and BODIPY-C11 cytofluorimetric assays, respectively. Ferroptosis markers GPX4 and VDAC2 were measured by Western blot. FtH1 knockdown was performed by using siRNA. Results: To generate spheroids, HEY and PEO1 cells prevent LIP accumulation by upregulating FtH1. 3D HEY moderately increases FtH1, and LIP is only slightly reduced. 3D PEO1upregulate FtH1 and LIP results significantly diminished. HEY tumor spheroids prevent iron import downregulating CD71, while PEO1 cells strongly enhance it. Intracellular ROS drop down during the 2D to 3D transition in both cell lines, but more significantly in PEO1 cells. Upon iron supplementation, PEO1 cells continue to enhance CD71 and FtH1 without accumulating the LIP and ROS and do not undergo ferroptosis. HEY, instead, accumulate LIP, undergo ferroptosis and attenuate their sphere-forming ability and invasiveness. FtH1 knockdown significantly reduces the generation of PEO1 tumor spheroids, although without sensitizing them to ferroptosis. Discussion: Iron metabolism reprogramming is a key event in the tumor spheroid generation of ovarian cancer cells. An iron-rich environment impairs the sphere-forming ability and causes cell death only in ferroptosis sensitive cells. A better understanding of ferroptosis sensitivity could be useful to develop effective treatments to kill ECM-detached ovarian cancer cells.

DMT1 differentially regulates mitochondrial complex activities to reduce glutathione loss and mitigate ferroptosis

Mitochondria are vital for energy production and redox homeostasis, yet knowledge of relevant mechanisms remains limited. Here, through a genome-wide CRISPR-Cas9 knockout screening, we have identified DMT1 as a major regulator of mitochondria membrane potential. Our findings demonstrate that DMT1 deficiency increases the activity of mitochondrial complex I and reduces that of complex III. Enhanced complex I activity leads to increased NAD+ production, which activates IDH2 by promoting its deacetylation via SIRT3. This results in higher levels of NADPH and GSH, which improve antioxidant capacity during Erastin-induced ferroptosis. Meanwhile, loss of complex III activity impairs mitochondrial biogenesis and promotes mitophagy, contributing to suppression of ferroptosis. Thus, DMT1 differentially regulates activities of mitochondrial complex I and III to cooperatly suppress Erastin-induced ferroptosis. Furthermore, NMN, an alternative method of increasing mitochondrial NAD+, exhibits similar protective effects against ferroptosis by boosting GSH in a manner similar to DMT1 deficiency, shedding a light on potential therapeutic strategy for ferroptosis-related pathologies.

Relevant Membrane Transport Proteins as Possible Gatekeepers for Effective Pharmacological Ascorbate Treatment in Cancer

Despite the increasing number of newly diagnosed malignancies worldwide, therapeutic options for some tumor diseases are unfortunately still limited. Interestingly, preclinical but also some clinical data suggest that the administration of pharmacological ascorbate seems to respond well, especially in some aggressively growing tumor entities. The membrane transport and channel proteins are highly relevant for the use of pharmacological ascorbate in cancer therapy and are involved in the transfer of active substances such as ascorbate, hydrogen peroxide, and iron that predominantly must enter malignant cells to induce antiproliferative effects and especially ferroptosis. In this review, the relevant conveying proteins from cellular surfaces are presented as an integral part of the efficacy of pharmacological ascorbate, considering the already known genetic and functional features in tumor tissues. Accordingly, candidates for diagnostic markers and therapeutic targets are mentioned.

Antimicrobial peptides CS-piscidin-induced cell death involves activation of RIPK1/PARP, and modification with myristic acid enhances its stability and tumor-targeting capability

Ovarian cancer (OC) is a highly lethal gynecological malignancy, often diagnosed at advanced stages with limited treatment options. Here, we demonstrate that the antimicrobial peptide CS-piscidin significantly inhibits OC cell proliferation, colony formation, and induces cell death. Mechanistically, CS-piscidin causes cell necrosis by compromising the cell membrane. Furthermore, CS-piscidin can activate Receptor-interacting protein kinase 1 (RIPK1) and induce cell apoptosis by cleavage of PARP. To improve tumor targeting ability, we modified CS-piscidin by adding a short cyclic peptide, cyclo-RGDfk, to the C-terminus (CS-RGD) and a myristate to the N-terminus (Myr-CS-RGD). Our results show that while CS-RGD exhibits stronger anti-cancer activity than CS-piscidin, it also causes increased cytotoxicity. In contrast, Myr-CS-RGD significantly improves drug specificity by reducing CS-RGD toxicity in normal cells while retaining comparable antitumor activity by increasing peptide stability. In a syngeneic mouse tumor model, Myr-CS-RGD demonstrated superior anti-tumor activity compared to CS-piscidin and CS-RGD. Our findings suggest that CS-piscidin can suppress ovarian cancer via multiple cell death forms and that myristoylation modification is a promising strategy to enhance anti-cancer peptide performance.

Prognostic Significance of Iron Metabolism Related Genes in Human Lung Adenocarcinoma

Background

Iron metabolism related genes participate in cell proliferation, cell growth, and redox cycling in multiple cancers. Limited studies have revealed the roles and clinical significance of iron metabolism in the pathogenesis and prognosis of lung cancer.

Methods

A total of 119 iron metabolism related genes were extracted from MSigDB database and their prognostic values were determined in The Cancer Genome Atlas lung adenocarcinoma (TCGA-LUAD) dataset and the Gene Expression Profiling Interactive Analysis 2 (GEPIA 2) database. Immunohistochemistry technique and correlations with immune cell infiltration, gene mutation and drug resistance were used to identify the potential and underlying mechanisms of STEAP1 and STEAP2 as prognostic biomarkers of LUAD.

Results

The expression of STEAP1 and STEAP2 are negatively associated with the prognosis of LUAD patients both at the mRNA and protein level. The expression of STEAP1 and STEAP2 was not only negatively correlated with the trafficking degree of CD4+ T immune cells and positively related to most immune cells' trafficking degree, but also significantly associated with gene mutation status, particularly with mutations on TP53 and STK11. Four types of drug resistance showed significant correlation with the expression level of STEAP1 while 13 types of drug resistance were associated with the expression level of STEAP2.

Conclusion

Multiple iron metabolism related genes including STEAP1 and STEAP2 are significantly associated with the prognosis of LUAD patients. STEAP1 and STEAP2 might affect the prognosis of LUAD patients partially through immune cell infiltration, gene mutation and drug resistance, which indicated they were independent prognostic factors for LUAD patients.

Engineering Alendronate-Composed Iron Nanochelator for Efficient Peritoneal Carcinomatosis Treatment

Iron is an essential element for various cellular metabolism. Cancer cells also have high requirement of iron in their proliferation, invasion, and metastasis processes. Alendronate (ALN), a kind of FDA-approved bisphosphonates with metal-chelating capability, is initially certified to selectively bind to intracellular Fe3+ theoretically and experimentally in this study. Hence, CaALN iron nanochelator is rationally designed to kill cancer cells by synergism of Fe-depletion and calcium accumulation. In vitro experiments and RNA sequencing analysis indicate that CaALN nanomedicine inhibits the proliferation of cancer cells by depleting Fe, interfering with DNA replication, and triggering intracellular reactive oxygen species (ROS). Meanwhile, released Ca2+ and ROS mutually promote and induce damage of cellular macromolecules, which leads to mitochondrial apoptosis of cancer cells. In an intraperitoneal disseminated mouse model with the human ovarian cancer cells SKOV3, CaALN nanoparticles selectively accumulate in tumor tissues and result in significant retardation of tumor growth and ascites formation. The mean survival time of SKOV3-bearing mice in treatment group is prolonged from 33 to 90 d. These results indicate that the alendronate-originated iron chelator can serve as an efficient strategy for the treatment of peritoneal carcinomatosis.

Non-apoptotic cell death in ovarian cancer: Treatment, resistance and prognosis

Ovarian cancer is mostly diagnosed at an advanced stage due to the absence of effective screening methods and specific symptoms. Repeated chemotherapy resistance and recurrence before PARPi are used as maintenance therapies, lead to low survival rates and poor prognosis. Apoptotic cell death plays a crucial role in ovarian cancer, which is proved by current researches. With the ongoing development of targeted therapy, non-apoptotic cell death has shown substantial potential in tumor prevention and treatment, including autophagy, ferroptosis, necroptosis, immunogenic cell death, pyroptosis, alkaliptosis, and other modes of cell death. We systematically reviewed the research progress on the role of non-apoptotic cell death in the onset, development, and outcome of ovarian cancer. This review provides a more theoretical basis for exploring therapeutic targets, reversing drug resistance in refractory ovarian cancer, and establishing risk prediction models that help realize the clinical transformation of vital drugs.

CEMIP promotes extracellular matrix-detached prostate cancer cells survival by inhibiting ferroptosis

Cells detached from the extracellular matrix (ECM) can trigger different modes of cell death, and the survival of ECM‐detached cells is one of the prerequisites for the metastatic cascade. Ferroptosis, a form of iron‐dependent programmed cell death, has recently been found to be involved in matrix‐detached cancer cells. However, the molecular mechanisms by which ECM‐detached cells escape ferroptosis are not fully understood. Here, we observed that cell migration‐inducing protein (CEMIP) upregulation facilitates ferroptosis resistance during ECM detachment by promoting cystine uptake in prostate cancer (PCa) cells. Meanwhile, silencing CEMIP causes it to lose its ability to promote cystine uptake and inhibit ferroptosis. Mechanistically, the interaction of CEMIP with inositol 1,4,5‐trisphosphate receptor type 3 (ITPR3) modulates calcium ion (Ca²⁺) leakage from the endoplasmic reticulum, activating calcium/calmodulin‐dependent protein kinase II (CaMKII), which further facilitates nuclear factor erythroid 2‐related factor 2 (NRF2) phosphorylation and nuclear localization, leading to elevated transcription of solute carrier family 7 member 11 (SLC7A11), a glutamate/cystine antiporter, in PCa cells. Our findings delineate a novel role of CEMIP in ferroptosis resistance during ECM detachment and provide new insights into therapeutic strategies for metastatic PCa.

Sodium molybdate inhibits the growth of ovarian cancer cells via inducing both ferroptosis and apoptosis

Ovarian cancer has the most mortality of all gynecologic malignancies. High-grade serous ovarian carcinoma (HGSOC) is the most common and deadly type of ovarian cancer. Tumor recurrence occurs due to the emergence of chemotherapy resistance. Thus, searching for new therapeutic strategies is essential for the management of ovarian cancer. Deregulation of iron metabolism can be used by ovarian cancer cells to survive, proliferate and metastasize. Here we report that sodium molybdate, a soluble molybdenum (Mo) compound, induces the elevation of the labile iron pool (LIP) in ovarian cancer cells, correlated with the down-regulation of genes involved in extracellular matrix organization. Sodium molybdate also induces depletion of glutathione (GSH) through mediating the production of nitric oxide (NO). Elevation of LIP and depletion of GSH promote the ferroptosis of ovarian cancer cells. Meanwhile, nitric oxide induces mitochondrial damage through inhibiting mitochondrial aconitase activity, ATP production, and mitochondrial membrane potential, leading to apoptosis of ovarian cancer cells. In vivo study shows that sodium molybdate reduces tumor burden in nude mice. Xenografts treated with sodium molybdate are characterized by obvious iron accumulation, increased expression of the iron storage protein ferritin, and lipid peroxide product 4-hydroxynonenal. In addition, an elevated percentage of apoptotic cells is observed in xenografts treated with sodium molybdate. Taken together, these results demonstrate that sodium molybdate can induce both ferroptosis and apoptosis of ovarian cancer cells, making it a potential therapeutic candidate for ovarian cancer.

The Role of Iron in Cancer Progression

Iron is an essential trace element for the human body, and its deficiency or excess can induce a variety of biological processes. Plenty of evidences have shown that iron metabolism is closely related to the occurrence and development of tumors. In addition, iron plays an important role in cell death, which is very important for the development of potential strategies for tumor treatment. Here, we reviewed the latest research about iron metabolism disorders in various types of tumors, the functions and properties of iron in ferroptosis and ferritinophagy, and new opportunities for iron-based on treatment methods for tumors, providing more information regarding the prevention and treatment of tumors.