Serum iron status and the risk of breast cancer in the European population: a two-sample Mendelian randomisation study

Mendelian randomization analysis of modifiable risk factors for breast cancer

This review explores the role of Mendelian randomization (MR) in the analysis of modifiable risk factors for breast cancer. Breast cancer is the most common cancer in women, with risk factors including lifestyle, genetic predisposition, and hormonal influences. Mendelian randomization (MR) is a robust epidemiological tool, uses genetic variants to assess causal relationships between exposures and breast cancer risk. Evidence suggests that obesity, particularly in adulthood, is associated with elevated risk, while early obesity may be protective. Alcohol consumption shows a complex relationship, with adverse effects associated with problematic drinking behaviors rather than moderate drinking. Physical activity is associated with reduced breast cancer risk, likely through hormonal and metabolic pathways. Dietary factors, such as higher intake of monounsaturated fatty acids and vitamin E, appear protective, highlighting the importance of dietary choices. Methodological considerations, including pleiotropy and sample size, are crucial to ensure the validity of MR studies. Overall, this synthesis of existing studies demonstrates the importance of Mendelian randomization (MR) in identifying causal links between modifiable risk factors and breast cancer, which is essential for developing targeted prevention strategies.

Risk Role of Genetically Predicted Serum Iron Status on Thyroid Cancer

Previous research has not clearly illustrated the impact of serum iron status on thyroid cancer. Bi-directional and multivariable Mendelian randomization (MVMR) analyses were conducted to determine the causative effects of serum iron status on thyroid cancer. Genetic markers for serum iron status, including serum iron, ferritin, transferrin saturation (TSTA), and transferrin, were acquired from the Genetics of Iron Status. The primary analytical method employed was inverse variance weighting, supplemented by other sensitivity approaches to validate the consistency of the results. Genetically predicted serum iron, ferritin, and TSTA were found to increase the risk of thyroid cancer. However, there was no causal link between transferrin levels and the risk of thyroid cancer. The causal link remained strong in the reverse MR and MVMR. Furthermore, serum iron status had no causal effect on benign neoplasms of the thyroid gland based on the two-sample MR analysis. Our MR study provides novel evidence that serum iron, ferritin, and TSTA are associated with thyroid cancer, but not with benign neoplasms of the thyroid gland. These markers could be useful for differential diagnosis. Strategies to lower serum iron levels may reduce the burden of thyroid cancer.

The marine xanthophyll diatoxanthin as ferroptosis inducer in MDAMB231 breast cancer cells

Marine biotopes are considered as a huge reservoir of biodiversity and chemodiversity, the latter potentially providing new treats for health prevention. Among the emphasized marine biocenosis, microorganisms such as microalgae propose suitable solutions to address eco-sustainability or biorefinery topics. The health interests of the xanthophyll diatoxanthin (Dt), a photoprotective and antioxidant pigment synthetized by diatoms, have been recently documented. This study deeply explores the capacity of Dt to intercept cancer progression and addresses the Dt -induced cell death in breast cancer. It is crucial to know which signalling pathway explaining its function is induced by the molecule in the targeted cells. This study disentangled the intracellular effects of Dt in MDAMB231 breast cancer cells. The results highlighted the inhibition of glutathione synthesis through cysteine transport blockage, that in turn, induced an iron accumulation and increase in lipid peroxidation. Those features represent the principal hallmarks of intracellular ferroptosis pathway. Ferroptosis being considered as one of the cell death most promising in fighting cancer development (e.g. in breast cancer) this study reinforces the scientific/biomedical interests on Dt and the diatoms' resource and paves the way to explore its suitability in vivo.

Extracting Knowledge from Machine Learning Models to Diagnose Breast Cancer

This study explored the application of explainable machine learning models to enhance breast cancer diagnosis using serum biomarkers, contrary to many studies that focus on medical images and demographic data. The primary objective was to develop models that are not only accurate but also provide insights into the factors driving predictions, addressing the need for trustworthy AI in healthcare. Several classification models were evaluated, including OneR, JRIP, the FURIA, J48, the ADTree, and the Random Forest, all of which are known for their explainability. The dataset included a variety of biomarkers, such as electrolytes, metal ions, marker proteins, enzymes, lipid profiles, peptide hormones, steroid hormones, and hormone receptors. The Random Forest model achieved the highest accuracy at 99.401%, followed closely by JRIP, the FURIA, and the ADTree at 98.802%. OneR and J48 achieved 98.204% accuracy. Notably, the models identified oxytocin as a key predictive biomarker, with most models featuring it in their rules. Other significant parameters included GnRH, β-endorphin, vasopressin, IRAP, and APB, as well as factors like iron, cholinesterase, the total protein, progesterone, 5-nucleotidase, and the BMI, which are considered clinically relevant to breast cancer pathogenesis. This study discusses the roles of the identified parameters in cancer development, thus underscoring the potential of explainable machine learning models for enhancing early breast cancer diagnosis by focusing on explainability and the use of serum biomarkers.The combination of both can lead to improved early detection and personalized treatments, emphasizing the potential of these methods in clinical settings. The identified markers also provide additional research and therapeutic targets for breast cancer pathogenesis and a deep understanding of their interactions, advancing personalized approaches to breast cancer management.

Serum iron status and the risk of female infertility in European populations: A two-sample Mendelian randomization study

The relationship between iron status and female infertility has been observed in several studies, yet its causal nature remains ambiguous. We employed univariate Mendelian randomization (MR) analyses to explore the potential causal connection between these 2 factors. For our analysis, genetic instrumental variables pertaining to iron status were selected using data from the Iron Status Genetics Consortium, encompassing 48,972 individuals of European descent from 19 cohorts (11 discovery and 8 replication). For female infertility data, we referred to FinnGen Consortium Release 9, which includes 11,442 cases and 107,564 controls. Our MR approach utilized both a conservative strategy (involving single nucleotide polymorphisms pertinent to general iron status) and a liberal strategy (encompassing single nucleotide polymorphisms linked to any iron status indicator). The conservative approach relied on inverse variance-weighted methods, whereas the liberal strategy integrated inverse variance weighted with MR-Egger regression, the weighted median approach, and simple mode techniques. The conservative strategy did not reveal a significant link between iron status and female infertility risk. Conversely, the liberal strategy indicated a positive correlation specifically between serum iron levels and female infertility risk (odds ratio from MR: 1.225; 95% confidence interval: 1.064-1.410; P = .030), while no significant associations were found for other iron indicators (P > 0.05). Our MR investigation suggests a potential positive association between serum iron levels and the risk of female infertility, while other iron markers do not appear to significantly influence this risk. These findings highlight the need for further research into the possible connection between serum iron status and female infertility risk.

Emerging role of necroptosis, pyroptosis, and ferroptosis in breast cancer: New dawn for overcoming therapy resistance

Breast cancer (BC) is one of the primary causes of death in women worldwide. The challenges associated with adverse outcomes have increased significantly, and the identification of novel therapeutic targets has become increasingly urgent. Regulated cell death (RCD) refers to a type of cell death that can be regulated by several different biomacromolecules, which is distinctive from accidental cell death (ACD). In recent years, apoptosis, a representative RCD pathway, has gained significance as a target for BC medications. However, tumor cells exhibit avoidance of apoptosis and result in treatment resistance, which emphasizes further studies devoted to alternative cell death processes, namely necroptosis, pyroptosis, and ferroptosis. Here, in this review, we focus on summarizing the crucial signaling pathways of these RCD in BC. We further discuss the molecular mechanism and potentiality in clinical application of several prospective drugs, nanoparticles, and other small compounds targeting different RCD subroutines of BC. We also discuss the benefits of modulating RCD processes on drug resistance and the advantages of combining RCD modulators with conventional treatments in BC. This review will deepen our understanding of the relationship between RCD and BC, and shed new light on future directions to attack cancer vulnerabilities with RCD modulators for therapeutic purposes.

Iron status and non-alcoholic fatty liver disease: A Mendelian randomization study

OBJECTIVES

The aim of this study was to assess the association of genetically determined iron status with the risk for non-alcoholic fatty liver disease (NAFLD) using two-sample Mendelian randomization (MR) analysis.

METHODS

We applied single nucleotide polymorphisms (SNPs) associated at genome-wide significance with iron status proxied by serum iron, ferritin, transferrin, and transferrin saturation from the Genetics of Iron status Consortium (N = 48 793), in a genome-wide association study of 1664 NAFLD cases and 400 055 controls from the United Kingdom Biobank. A SNP associated with multiple markers of iron status was only applied to one marker with the strongest association in the main analysis. Their effects on NAFLD were calculated using inverse variance weighting after excluding SNPs associated with alkaline phosphatase and lipid metabolism.

RESULTS

The risk for NAFLD is negatively associated with genetically predicted serum transferrin level with a 20% reduction in NAFLD risk per SD (0.65g/L) increase in transferrin (95% confidence interval [CI], 0.66-0.97), and trending positive association with transferrin saturation (odds ratio [OR], 1.50; 95% CI, 0.96-2.35) but it was not associated with serum iron (OR, 0.90; 95% CI, 0.63-1.29) and ferritin (OR, 1.33; 95% CI, 0.54-3.30).

CONCLUSIONS

MR analysis provided evidence that genetically predicted higher serum transferrin, indicating lower iron status, may be protective against NAFLD, whereas higher transferrin saturation, indicating higher iron status, might increase the risk for NAFLD and its pathogenesis.

Using Mendelian Randomization to Study the Role of Iron in Health and Disease

Iron has been shown to play a dual role in health and disease, with either a protective or harmful effect. Some of the contradictory findings from observational studies may be due to reverse causation, residual confounding, or small sample size. One approach that may overcome these limitations without the high cost of randomized control trials is the use of Mendelian randomization to examine the long-term role of iron in a variety of health outcomes. As there is emerging evidence employing Mendelian randomization as a method of assessing the role of micronutrients in health and disease, this narrative review will highlight recent Mendelian randomization findings examining the role of iron in cardiometabolic disorders, inflammation, neurological disorders, different cancers, and a number of other health-related outcomes.

Crosstalk between ferroptosis and steroid hormone signaling in gynecologic cancers

Ferroptosis is a novel types of regulated cell death and is widely studied in cancers and many other diseases in recent years. It is characterized by iron accumulation and intense lipid peroxidation that ultimately inducing oxidative damage. So far, signaling pathways related to ferroptosis are involved in all aspects of determining cell fate, including oxidative phosphorylation, metal-ion transport, energy metabolism and cholesterol synthesis progress, et al. Recently, accumulated studies have demonstrated that ferroptosis is associated with gynecological oncology related to steroid hormone signaling. This review trends to summarize the mechanisms and applications of ferroptosis in cancers related to estrogen and progesterone, which is expected to provide a theoretical basis for the prevention and treatment of gynecologic cancers.

Targeting ferroptosis, the achilles' heel of breast cancer: A review

Ferroptosis is referred as a novel type of cell death discovered in recent years with the feature of the accumulation of iron-dependent lipid reactive oxygen species. Breast cancer is one of the most common malignant cancers in women. There is increasing evidence that ferroptosis can inhibit breast cancer cell growth, improve the sensitivity of chemotherapy and radiotherapy and inhibit distant metastases. Therefore, ferroptosis can be regarded a new target for tumor suppression and may expand the landscape of clinical treatment of breast cancer. This review highlights the ferroptosis mechanism and its potential role in breast cancer treatment to explore new therapeutic strategies of breast cancer.

The causal association between iron status and the risk of autism: A Mendelian randomization study

Emerging evidence indicates a connection between serum iron levels and autism, but the underlying causal association is yet unclear. Thus, we performed two-sample Mendelian randomization (MR) analysis to evaluate the causal link between iron status on autism, using genetic instruments (p < 5E-08) strongly associated with iron status (N = 48,972), including serum iron, ferritin, transferrin levels, and transferrin saturation. Summary statistics of autism was obtained from two independent studies conducted by Psychiatric Genomics Consortium (PGC, Ncases = 5,305, Ncontrols = 5,305) and FinnGen Consortium (FC, Round six, Ncases = 344, Ncontrols = 258,095), respectively. Using the inverse-variance weighted (IVW) method, the combined results of PGC and FC demonstrated that genetically determined serum transferrin level was significantly associated with an increased risk of autism [odds ratio (OR) = 1.16, 95% CI: 1.03-1.30, p = 0.013]. There was no significant causal effect of serum iron (OR = 0.99, 95% CI: 0.72-1.37, p = 0.951), ferritin (OR = 0.88, 95% CI: 0.47-1.64, p = 0.676), and transferrin saturation (OR = 0.89, 95% CI: 0.72-1.09, p = 0.252) on autism. No obvious pleiotropy was found in this MR study. Taken together, our findings highlight that elevation of serum transferrin level might be associated with a high risk of autism, suggesting a potential role of iron deficiency in autism development. Future studies are warranted to clarify the underlying mechanism, which will pave a new path for the prevention and treatment of autism.

Pre-Clinical Insights into the Iron and Breast Cancer Hypothesis

Population studies, systematic reviews, and meta-analyses have revealed no relationship between iron status and breast cancer, a weak positive association, or a small protective effect of low iron status. However, in those studies, the authors concluded that further investigation was merited. The set of experiments reported here used preclinical models to assess the likely value of further investigation. The effects of iron status on the initiation and promotion stage of mammary carcinogenesis are reported. Using the classical model of cancer initiation in the mammary gland, 7,12 dimethyl-benz[α]anthracene-induced carcinogenesis was unaffected by iron status. Similarly, excess iron intake showed no effect on the promotion stage of 1-methyl-1-nitrosurea-induced mammary carcinogenesis, though iron deficiency exerted a specific inhibitory effect on the carcinogenic process. Though iron-mediated cellular oxidation is frequently cited as a potential mechanism for effects on breast cancer, no evidence of increased oxidative damage to DNA attributable to excess iron intake was found. The reported preclinical data fail to provide convincing evidence that the further evaluation of the iron–breast cancer risk hypotheses is warranted and underscore the value of redefining the referent group in population-based studies of iron–cancer hypotheses in other tissues.