Inhibition of glutathione metabolism attenuates esophageal cancer progression

Study on the Mechanism of FOXA2 Activation on Glutathione Metabolic Reprogramming Mediated by ETV4 Transcription to Facilitate Colorectal Cancer Malignant Progression

The metabolic imbalance of glutathione (GSH) has been widely recognized in most cancers, but the specific molecular mechanism of GSH metabolic regulation in the malignant progression of colorectal cancer (CRC) is unexplored. The objective of our project is to elucidate whether ETV4 affects the malignant progression of CRC through GSH metabolic reprogramming. Bioinformatics and molecular experiments measured the expression of ETV4 in CRC, and in vitro experiments explored the impact of ETV4 on CRC malignant progression. The Kyoto Encyclopedia of Genes and Genomes (KEGG) identified the pathway of ETV4 enrichment. The bioinformatics approach identified FOXA2 as an upstream regulatory factor of ETV4. The dual-luciferase assay, chromatin immunoprecipitation (ChIP) and co-immunoprecipitation (Co-IP) experiment verified the binding relationship between ETV4 and FOXA2. Cell viability, migration, and invasion abilities were determined by conducting CCK-8, wound healing, and Transwell assays, respectively. The expression levels of N-cadherin, E-cadherin, and vimentin were determined by utilizing immunofluorescence (IF). Metabolism-related enzymes GCLM, GCLC, and GSTP1 levels were detected to evaluate the GSH metabolism level by analyzing the GSH/GSSG ratio. In vivo experiments were performed to explore the effect of FOXA2/ETV4 on CRC progression, and the expression of related proteins was detected by western blot. ETV4 was highly expressed in CRC. Knocking down ETV4 suppressed CRC cell viability, migration, invasion, and epithelial-mesenchymal transition (EMT) progression in vitro. ETV4 was abundant in the GSH metabolic pathway, and overexpression of ETV4 facilitated CRC malignant progression through activation of the GSH metabolism. In addition, in vitro cellular experiments and in vivo experiments in nude mice confirmed that FOXA2 transcriptionally activated ETV4. Knocking down FOXA2 repressed the malignant phenotype of CRC cells by suppressing GSH metabolism. These effects were reversed by overexpressing ETV4. Our results indicated that FOXA2 transcriptionally activates ETV4 to facilitate CRC malignant progression by modulating the GSH metabolic pathway. Targeting the FOXA2/ETV4 axis or GSH metabolism may be an effective approach for CRC treatment.

Buthionine sulfoximine and chemoresistance in cancer treatments: a systematic review with meta-analysis of preclinical studies

Buthionine sulfoximine (BSO) is a synthetic amino acid that blocks the biosynthesis of reduced glutathione (GSH), an endogenous antioxidant cellular component present in tumor cells. GSH levels have been associated with tumor cell resistance to chemotherapeutic drugs and platinum compounds. Consequently, by depleting GSH, BSO enhances the cytotoxicity of chemotherapeutic agents in drug-resistant tumors. Therefore, the aim of this study was to conduct a systematic review with meta-analysis of preclinical studies utilizing BSO in cancer treatments. The systematic search was carried out using the following databases: PubMed, Web of Science, Scopus, and EMBASE up until March 20, 2023, in order to collect preclinical studies that evaluated BSO, alone or in association, as a strategy for antineoplastic therapy. One hundred nine investigations were found to assess the cytotoxic potential of BSO alone or in combination with other compounds. Twenty-one of these met the criteria for performing the meta-analysis. The evidence gathered indicated that BSO alone exhibits cytotoxic activity. However, this compound is generally used in combination with other antineoplastic strategies, mainly chemotherapy ones, to improve cytotoxicity to carcinogenic cells and treatment efficacy. Finally, this review provides important considerations regarding BSO use in cancer treatment conditions, which might optimize future studies as a potential adjuvant antineoplastic therapeutic tool.

DMMIC derivatization-assisted liquid chromatography-mass spectrometry method for metabolite profiling of the glutathione anabolic pathway in esophageal cancer tissues and cells

In this work, a new pyrylium derivatization-assisted liquid chromatography-mass spectrometry (LC-MS) method was developed for metabolite profiling of the glutathione anabolic pathway (GAP) in cancer tissues and cells. The pyrylium salt of 6,7-dimethoxy-3-methyl isochromenylium tetrafluoroborate (DMMIC) was used to label the amino group of metabolites, and a reductant of dithiothreitol (DTT) was employed to stabilize the thiol group. By combining DMMIC derivatization with LC-MS, it was feasible to quantify the 13 main metabolites on the GAP in complex biological samples, which had good linearity (R2 = 0.9981-0.9999), precision (interday precision of 1.6%-19.0% and intraday precision of 1.4%-19.8%) and accuracy (83.4%-115.7%). Moreover, the recovery assessments in tissues (82.5%-107.3%) and in cells (98.1%-118.9%) with GSH-13C2, 15N, and Cys-15N demonstrated the reliability of the method in detecting tissues and cells. Following a methodological evaluation, the method was applied successfully to investigate difference in the GAP between the carcinoma and para-carcinoma tissues of esophageal squamous cell carcinoma (ESCC) and the effect of p-hydroxycinnamaldehyde (CMSP) on the GAP in KYSE-150 esophageal cancer cells. The results demonstrate that the developed method provides a promising new tool to elucidate the roles of GAP in physiological and pathological processes, which can contribute to research on drugs and diseases.

Exosome-mediated metabolic reprogramming: Implications in esophageal carcinoma progression and tumor microenvironment remodeling

Esophageal carcinoma is among the most fatal malignancies with increasing incidence globally. Tumor onset and progression can be driven by metabolic reprogramming, especially during esophageal carcinoma development. Exosomes, a subset of extracellular vesicles, display an average size of ∼100 nanometers, containing multifarious components (nucleic acids, proteins, lipids, etc.). An increasing number of studies have shown that exosomes are capable of transferring molecules with biological functions into recipient cells, which play crucial roles in esophageal carcinoma progression and tumor microenvironment that is a highly heterogeneous ecosystem through rewriting the metabolic processes in tumor cells and environmental stromal cells. The review introduces the reprogramming of glucose, lipid, amino acid, mitochondrial metabolism in esophageal carcinoma, and summarize current pharmaceutical agents targeting such aberrant metabolism rewiring. We also comprehensively overview the biogenesis and release of exosomes, and recent advances of exosomal cargoes and functions in esophageal carcinoma and their promising clinical application. Moreover, we discuss how exosomes trigger tumor growth, metastasis, drug resistance, and immunosuppression as well as tumor microenvironment remodeling through focusing on their capacity to transfer materials between cells or between cells and tissues and modulate metabolic reprogramming, thus providing a theoretical reference for the design potential pharmaceutical agents targeting these mechanisms. Altogether, our review attempts to fully understand the significance of exosome-based metabolic rewriting in esophageal carcinoma progression and remodeling of the tumor microenvironment, bringing novel insights into the prevention and treatment of esophageal carcinoma in the future.

Unraveling the Complexity of Regulated Cell Death in Esophageal Cancer: from Underlying Mechanisms to Targeted Therapeutics

Esophageal cancer (EC) is the sixth most common and the seventh most deadly malignancy of the digestive tract, representing a major global health challenge. Despite the availability of multimodal therapeutic strategies, the existing EC treatments continue to yield unsatisfactory results due to their limited efficacy and severe side effects. Recently, knowledge of the subroutines and molecular mechanisms of regulated cell death (RCD) has progressed rapidly, enhancing the understanding of key pathways related to the occurrence, progression, and treatment of many types of tumors, including EC. In this context, the use of small-molecule compounds to target such RCD subroutines has emerged as a promising therapeutic strategy for patients with EC. Thus, in this review, we firstly discussed the risk factors and prevention of EC. We then outlined the established treatment regimens for patients with EC. Furthermore, we not only briefly summarized the mechanisms of five best studied subroutines of RCD related to EC, including apoptosis, ferroptosis, pyroptosis, necroptosis and autophagy, but also outlined the recent advances in the development of small-molecule compounds and long non-coding RNA (lncRNA) targeting the abovementioned RCD subroutines, which may serve as a new therapeutic strategy for patients with EC in the future.

SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop

Studies have indicated dietary restriction of methionine/cystine provided a therapeutic benefit in diseases such as cancer. However, the molecular and cellular mechanisms that underlie the interaction between methionine/cystine restriction (MCR) and effects on esophageal squamous cell carcinoma (ESCC) have remained elusive. Here, we discovered the dietary restriction of methionine/cystine has a large effect on cellular methionine metabolism as assayed in a ECA109 derived xenograft model. RNA-seq and enrichment analysis suggested the blocked tumor progression was affected by ferroptosis, together with the NFκB signaling pathway activation in ESCC. Consistently, GSH content and GPX4 expression were downregulated by MCR both in vivo and in vitro. The contents of Fe²⁺ and MDA were negatively correlated with supplementary methionine in a dose-dependent way. Mechanistically, MCR and silent of SLC43A2, a methionine transporter, diminished phosphorylation of IKKα/β and p65. Blocked NFκB signaling pathway further decreased the expression of SLC43A2 and GPX4 in both mRNA and protein level, which in turn downregulated the methionine intake and stimulated ferroptosis, respectively. ESCC progression was inhibited by enhanced ferroptosis and apoptosis and impaired cell proliferation. In this study, we proposed a novel feedback regulation mechanism underlie the correlation between dietary restriction of methionine/cystine and ESCC progression. MCR blocked cancer progression via stimulating ferroptosis through the positive feedback loop between SLC43A2 and NFκB signaling pathways. Our results provided the theoretical basis and new targets for ferroptosis-based clinical antitumor treatments for ESCC patients.

Immunity Depletion, Telomere Imbalance, and Cancer-Associated Metabolism Pathway Aberrations in Intestinal Mucosa upon Short-Term Caloric Restriction

Systems cancer biology analysis of calorie restriction (CR) mechanisms and pathways has not been carried out, leaving therapeutic benefits unclear. Using metadata analysis, we studied gene expression changes in normal mouse duodenum mucosa (DM) response to short-term (2-weeks) 25% CR as a biological model. Our results indicate cancer-associated genes consist of 26% of 467 CR responding differential expressed genes (DEGs). The DEGs were enriched with over-expressed cell cycle, oncogenes, and metabolic reprogramming pathways that determine tissue-specific tumorigenesis, cancer, and stem cell activation; tumor suppressors and apoptosis genes were under-expressed. DEG enrichments suggest telomeric maintenance misbalance and metabolic pathway activation playing dual (anti-cancer and pro-oncogenic) roles. The aberrant DEG profile of DM epithelial cells is found within CR-induced overexpression of Paneth cells and is coordinated significantly across GI tract tissues mucosa. Immune system genes (ISGs) consist of 37% of the total DEGs; the majority of ISGs are suppressed, including cell-autonomous immunity and tumor-immune surveillance. CR induces metabolic reprogramming, suppressing immune mechanics and activating oncogenic pathways. We introduce and argue for our network pro-oncogenic model of the mucosa multicellular tissue response to CR leading to aberrant transcription and pre-malignant states. These findings change the paradigm regarding CR's anti-cancer role, initiating specific treatment target development. This will aid future work to define critical oncogenic pathways preceding intestinal lesion development and biomarkers for earlier adenoma and colorectal cancer detection.

Oxidative Stress and the Intersection of Oncogenic Signaling and Metabolism in Squamous Cell Carcinomas

Squamous cell carcinomas (SCCs) arise from both stratified squamous and non-squamous epithelium of diverse anatomical sites and collectively represent one of the most frequent solid tumors, accounting for more than one million cancer deaths annually. Despite this prevalence, SCC patients have not fully benefited from recent advances in molecularly targeted therapy or immunotherapy. Rather, decades old platinum-based or radiation regimens retaining limited specificity to the unique characteristics of SCC remain first-line treatment options. Historically, a lack of a consolidated perspective on genetic aberrations driving oncogenic transformation and other such factors essential for SCC pathogenesis and intrinsic confounding cellular heterogeneity in SCC have contributed to a critical dearth in effective and specific therapies. However, emerging evidence characterizing the distinct genomic, epigenetic, and metabolic landscapes of SCC may be elucidating unifying features in a seemingly heterogeneous disease. In this review, by describing distinct metabolic alterations and genetic drivers of SCC revealed by recent studies, we aim to establish a conceptual framework for a previously unappreciated network of oncogenic signaling, redox perturbation, and metabolic reprogramming that may reveal targetable vulnerabilities at their intersection.

Oxidative Stress-Inducing Anticancer Therapies: Taking a Closer Look at Their Immunomodulating Effects

Cancer cells are characterized by higher levels of reactive oxygen species (ROS) compared to normal cells as a result of an imbalance between oxidants and antioxidants. However, cancer cells maintain their redox balance due to their high antioxidant capacity. Recently, a high level of oxidative stress is considered a novel target for anticancer therapy. This can be induced by increasing exogenous ROS and/or inhibiting the endogenous protective antioxidant system. Additionally, the immune system has been shown to be a significant ally in the fight against cancer. Since ROS levels are important to modulate the antitumor immune response, it is essential to consider the effects of oxidative stress-inducing treatments on this response. In this review, we provide an overview of the mechanistic cellular responses of cancer cells towards exogenous and endogenous ROS-inducing treatments, as well as the indirect and direct antitumoral immune effects, which can be both immunostimulatory and/or immunosuppressive. For future perspectives, there is a clear need for comprehensive investigations of different oxidative stress-inducing treatment strategies and their specific immunomodulating effects, since the effects cannot be generalized over different treatment modalities. It is essential to elucidate all these underlying immune effects to make oxidative stress-inducing treatments effective anticancer therapy.

Oridonin induces ferroptosis by inhibiting gamma-glutamyl cycle in TE1 cells

Oridonin (Ori) is a natural tetracyclic diterpenoid active compound with excellent antitumor activity, but the mechanism of Ori on esophageal cancer cell, TE1, remains unclear. In this study, we examined the levels of intracellular iron, malondialdehyde, and reactive oxygen species after Ori treatment, while interfering with the effects of Ori with ferroptosis inhibitor, demonstrating that Ori's inhibition of TE1 cell proliferation is associated with ferroptosis. To understand the molecular mechanism of Ori, we performed UPLC-MS/MS metabolomics profiling on TE1 cells, which show that gamma-glutamyl amino acids (gamma-glutamylleucine, gamma-glutamylvaline), 5-oxoproline, glutamate, GSH, and GSSG are changed significantly after Ori treatment. Meanwhile, the activity of gamma-glutamyl transpeptidase 1 (GGT1) decreased. This revealed that Ori inhibited the gamma-glutamyl cycle in TE1 cells. Furthermore, we found that Ori can covalently bind to cysteine to form the conjugate oridonin-cysteine (Ori-Cys), resulting in the inhibition of glutathione synthesis, which is consistent with the decrease in the enzymatic activity of glutamate cysteine ligase catalytic subunit (GCLC). Eventually, the value of intracellular GSH/GSSG was reduced, and the enzymatic activity of the glutathione peroxidase 4 (GPX4) was significantly decreased. In conclusion, our experiments indicated that Ori can inhibit the gamma-glutamyl cycle, thereby inducing ferroptosis to exert anti-cancer activity.

Survival of rats bearing advanced intracerebral F 98 tumors after glutathione depletion and microbeam radiation therapy: conclusions from a pilot project

Background

Resistance to radiotherapy is frequently encountered in patients with glioblastoma multiforme. It is caused at least partially by the high glutathione content in the tumour tissue. Therefore, the administration of the glutathione synthesis inhibitor Buthionine-SR-Sulfoximine (BSO) should increase survival time.

Methods

BSO was tested in combination with an experimental synchrotron-based treatment, microbeam radiation therapy (MRT), characterized by spatially and periodically alternating microscopic dose distribution. One hundred thousand F98 glioma cells were injected into the right cerebral hemisphere of adult male Fischer rats to generate an orthotopic small animal model of a highly malignant brain tumour in a very advanced stage. Therapy was scheduled for day 13 after tumour cell implantation. At this time, 12.5% of the animals had already died from their disease.

The surviving 24 tumour-bearing animals were randomly distributed in three experimental groups: subjected to MRT alone (Group A), to MRT plus BSO (Group B) and tumour-bearing untreated controls (Group C). Thus, half of the irradiated animals received an injection of 100 μM BSO into the tumour two hours before radiotherapy.

Additional tumour-free animals, mirroring the treatment of the tumour-bearing animals, were included in the experiment. MRT was administered in bi-directional mode with arrays of quasi-parallel beams crossing at the tumour location. The width of the microbeams was ≈28 μm with a center-to-center distance of ≈400 μm, a peak dose of 350 Gy, and a valley dose of 9 Gy in the normal tissue and 18 Gy at the tumour location; thus, the peak to valley dose ratio (PVDR) was 31.

Results

After tumour-cell implantation, otherwise untreated rats had a mean survival time of 15 days. Twenty days after implantation, 62.5% of the animals receiving MRT alone (group A) and 75% of the rats given MRT + BSO (group B) were still alive. Thirty days after implantation, survival was 12.5% in Group A and 62.5% in Group B. There were no survivors on or beyond day 35 in Group A, but 25% were still alive in Group B. Thus, rats which underwent MRT with adjuvant BSO injection experienced the largest survival gain.

Conclusions

In this pilot project using an orthotopic small animal model of advanced malignant brain tumour, the injection of the glutathione inhibitor BSO with MRT significantly increased mean survival time.