Gadolinium chloride elicits apoptosis in human osteosarcoma U-2 OS cells through extrinsic signaling, intrinsic pathway and endoplasmic reticulum stress

Toxicity Mechanisms of Gadolinium and Gadolinium-Based Contrast Agents-A Review

Gadolinium-based contrast agents (GBCAs) have been used for more than 30 years to improve magnetic resonance imaging, a crucial tool for medical diagnosis and treatment monitoring across multiple clinical settings. Studies have shown that exposure to GBCAs is associated with gadolinium release and tissue deposition that may cause short- and long-term toxicity in several organs, including the kidney, the main excretion organ of most GBCAs. Considering the increasing prevalence of chronic kidney disease worldwide and that most of the complications following GBCA exposure are associated with renal dysfunction, the mechanisms underlying GBCA toxicity, especially renal toxicity, are particularly important. A better understanding of the gadolinium mechanisms of toxicity may contribute to clarify the safety and/or potential risks associated with the use of GBCAs. In this work, a review of the recent literature concerning gadolinium and GBCA mechanisms of toxicity was performed.

Expression of GRP78 and its copartners in HEK293 and pancreatic cancer cell lines (BxPC-3/PANC-1) exposed to MRI and CT contrast agents

Endoplasmic reticulum (ER) stress-associated chaperones trigger a defense mechanism called as unfolded protein response (UPR) which can manage apoptosis and be determinative in cell fate. Both anticancer drug effects and potential toxicity effects of magnetic resonance imaging (MRI) and computed tomography (CT) contrast agents were aimed to be evaluated. For this purpose, we investigated expression profiles of endoplasmic reticulum stress-associated chaperone molecules in human pancreatic tumor lines BxPC-3 and PANC-1 and control human embryonic kidney cells 293 (HEK293) induced with a variety of gadolinium and iohexol contrast agents. Protein expression levels of ER stress-associated chaperones (master regulator: GRP78/Bip and its copartners: Calnexin, Ero1, PDI, CHOP, IRE1α and PERK) were evaluated with Western blotting. Expression levels at mRNA level were also assessed for GRP78/Bip and CHOP with real-time PCR. Induction of cells was carried out with four different Gd-based contrast agents (GBCAs): (Dotarem, Optimark, Primovist and Gadovist) and two different iohexol agents (Omnipol, Omnipaque). CT contrast agents tested in the study did not result in significant ER stress in HEK293 cells. However, they do not seem to have theranostic potential in pancreas cancer through ER pathway. The potential efficiency of macrocyclic MRI contrast agents to provoke apoptosis via ER stress-associated chaperones in BxPC-3 cells lends credibility for their future theranostic use in pancreas cancer as long as undesired toxicity effects were carefully considered. ER stress markers and/or contrast agents seem to have promising potential to be translated into the clinical practice to manage pancreas cancer progression.

Gadolinium-based contrast agents suppress adipocyte differentiation in 3T3-L1 cells

Gadolinium-based contrast agents (GBCAs) are widely used in magnetic resonance imaging (MRI) to improve the sensitivity and enhance diagnostic performance. GBCAs are mostly eliminated from the body through the kidney after administration; however small amounts of gadolinium are retained in the brain and other tissues. Although there is increasing concern about the adverse health effects of gadolinium, the cellular effects of GBCAs remains poorly understood. Here, we elucidated the potential cytotoxicity of the GBCAs Omniscan and Gadovist in 12 different cell lines, especially 3T3-L1 adipocyte cell line. Omniscan and Gadovist treatments significantly increased intracellular gadolinium levels in 3T3-L1 cells in a time- and dose-dependent manner. Additionally, Omniscan and Gadovist treatments downregulated the expression of adipocyte differentiation markers, including peroxisome proliferator-activated receptor γ (PPARG), adiponectin (ADIPOQ), and fatty acid-binding protein (FABP4), in 3T3-L1 cells, especially during early differentiation (day 0-2). Moreover, histological analysis using Oil red O staining showed that gadolinium chloride (GdCl₃) treatment suppressed lipid droplet accumulation and the expression of adipocyte differentiation markers. Overall, the results showed that Omniscan and Gadovist treatment suppressed adipocyte differentiation in 3T3-L1 cells, contributing to the understanding of the potential toxic effects of GBCA exposure.

Mechanism and Role of Endoplasmic Reticulum Stress in Osteosarcoma

Osteosarcoma is the most common malignant bone tumor, often occurring in children and adolescents. The etiology of most patients is unclear, and the current conventional treatment methods are chemotherapy, radiotherapy, and surgical resection. However, the sensitivity of osteosarcoma to radiotherapy and chemotherapy is low, and the prognosis is poor. The development of new and useful treatment strategies for improving patient survival is an urgent need. It has been found that endoplasmic reticulum (ER) stress (ERS) affects tumor angiogenesis, invasion, etc. By summarizing the literature related to osteosarcoma and ERS, we found that the unfolded protein response (UPR) pathway activated by ERS has a regulatory role in osteosarcoma proliferation, apoptosis, and chemoresistance. In osteosarcoma, the UPR pathway plays an important role by crosstalk with autophagy, oxidative stress, and other pathways. Overall, this article focuses on the relationship between ERS and osteosarcoma and reviews the potential of drugs or gene targets associated with ERS for the treatment of osteosarcoma.

Effects of chemical forms of gadolinium on the spleen in mice after single intravenous administration

Gadolinium-based contrast agents (GBCAs) are widely used to improve tissue contrast during magnetic resonance imaging. Exposure to GBCAs can result in gadolinium deposition within human tissues and has become a clinical concern because of the potential toxic effects of free gadolinium (Gd³⁺). Here, we report the impact of a single administration of GBCAs (Omniscan and Gadovist), and Gd³⁺ on mouse tissues. Five-week-old male BALB/c mice were injected intravenously with GBCAs or Gd³⁺. Seven days after injection, relatively high levels of gadolinium were detected in the spleen (118.87 nmol/g tissue), liver (83.00 nmol/g tissue), skin (48.56 nmol/g tissue), and kidneys (25.59 nmol/g tissue) of the Gd(NO₃)₃ (high dose: 0.165 mmol/kg) group; in the bones (11.12 nmol/g tissue), kidneys (7.49 nmol/g tissue), teeth (teeth: 6.18 nmol/g tissue), and skin (2.43 nmol/g tissue) of the Omniscan (high dose: 1.654 mmol/kg) group and in the kidneys (16.36 nmol/g tissue) and skin (4.88 nmol/g tissue) of the Gadovist (high dose: 3.308 mmol/kg) group. Enlargement of the spleen was observed in the Gd³⁺ group (p < 0.05), but not in the Omniscan or Gadovist groups. Gd³⁺ caused iron accumulation around the white pulp of the spleen, suggesting that enlargement of the spleen is, at least in part, associated with Gd³⁺ and/or iron accumulation. Our results may help elucidate the relative risks of different types of gadolinium agents, the mechanisms involved, and even recognition of potential toxic effects of GBCAs.

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The tissue deposition of gadolinium influenced by the chemical forms of gadolinium.

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Gd³⁺ causes enlargement and iron deposition in the spleen of mice.

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The spleen is a potential target for the release of Gd³⁺ from GBCAs.

Cytotoxic lanthanum oxide nanoparticles sensitize glioblastoma cells to radiation therapy and temozolomide: an in vitro rationale for translational studies

Glioblastoma (GBM) is a malignant brain tumour with a dismal prognosis, despite best treatment by surgical resection, radiation therapy (RT) and chemotherapy with temozolomide (TMZ). Nanoparticle (NP) therapy is an emerging consideration due to the ability of NPs to be formulated and cross the blood brain barrier. Lanthanum oxide (La2O3) NPs are therapeutically advantageous due to the unique chemical properties of lanthanum making it cytotoxic to cancers, and able to enhance existing anti-cancer treatments. However, La2O3 NPs have yet to be thoroughly investigated in brain tumors. We show that these NPs can reach the brain after venous injection, penetrate into GBM cells via endocytosis, dissociate to be cytotoxic, and enhance the therapeutic effects of RT and TMZ. The mechanisms of cell death by La2O3 NPs were found to be multifaceted. Increasing NP concentration was correlated to increased intrinsic and extrinsic apoptosis pathway markers in a radical oxygen species (ROS)-dependent manner, as well as involving direct DNA damage and autophagic pathways within GBM patient-derived cell lines. NP interactions to sensitize GBM to RT and TMZ were shown to involve these pathways by enhancing ROS and apoptotic mechanisms. We therefore demonstrate the therapeutic potential of La2O3 NPs to treat GBM cells in vitro, and encourage translational exploration in the future.

Significant contribution of autophagy in mitigating cytotoxicity of gadolinium ions

Gadolinium-based contrast agents (GBCAs) are widely used in clinical magnetic resonance imaging (MRI). Free gadolinium ions (Gd³⁺) released from GBCAs potentially increase the risk of GBCA-related toxicity. However, the cellular responses to Gd³⁺ and the underlying mechanisms responsible for protection against Gd³⁺ remain poorly understood. Recently, autophagy has been considered a cell survival mechanism against various toxic metals. Here, we investigated the relationship between Gd³⁺ and autophagy, as well as the effect of autophagy inhibition on the survival of cells exposed to Gd³⁺. We found that the increased expression of microtubule-associated protein 1 light chain 3 (LC3)-II, a marker protein of autophagy, in Gd³⁺-exposed human embryonic kidney 293 (HEK293) cells. Moreover, we found a greater accumulation of LC3-II after exposure to an autophagy inhibitor, chloroquine (CQ), combined with Gd³⁺ than that after exposure to CQ alone, suggesting that Gd³⁺ activated autophagy in HEK293 cells. Furthermore, we found that Gd³⁺ reduced cell viability, which was more pronounced after CQ treatment. Our findings indicated that autophagy exerted a cytoprotective effect against Gd³⁺ toxicity, suggesting a potential link between autophagy and GBCA-associated adverse events.

Toxicity Mechanism of Gadolinium Oxide Nanoparticles and Gadolinium Ions in Human Breast Cancer Cells

Background:

Due to the potential advantages of Gadolinium Nanoparticles (NPs) over gadolinium elements, gadolinium based NPs are currently being explored in the field of MRI. Either in elemental form or nanoparticulate form, gadolinium toxicity is believed to occur due to the deposition of gadolinium ion (designated as Gd3+ ion or simply G ion).

Objective:

There is a serious lack of literature on the mechanisms of toxicity caused by either gadolinium-based NPs or ions. Breast cancer tumors are often subjected to MRIs, therefore, human breast cancer (MCF-7) cells could serve as an appropriate in vitro model for the study of Gadolinium Oxide (GO) NP and G ion.

Methods:

Cytotoxicity and oxidative damage was determined by quantifying cell viability, cell membrane damage, and Reactive Oxygen Species (ROS). Intracellular Glutathione (GSH) was measured along with cellular Total Antioxidant Capacity (TAC). Autophagy was determined by using Monodansylcadaverine (MDC) and Lysotracker Red (LTR) dyes in tandem. Mitochondrial Membrane Potential (MMP) was measured by JC-1 fluorescence. Physicochemical properties of GO NPs were characterized by field emission transmission electron microscopy, X-ray diffraction, and energy dispersive spectrum.

Results:

A time- and concentration-dependent toxicity and oxidative damage was observed due to GO NPs and G ions. Bax/Bcl2 ratios, FITC-7AAD double staining, and cell membrane blebbing in phase-contrast images all suggested different modes of cell death induced by NPs and ions.

Conclusion:

In summary, cell death induced by GO NPs with high aspect ratio favored apoptosis-independent cell death, whereas G ions favored apoptosis-dependent cell death.

Toxicity Mechanism of Low Doses of NaGdF₄:Yb3+,Er3+ Upconverting Nanoparticles in Activated Macrophage Cell Lines

Gadolinium-doped nanoparticles (NPs) are regarded as promising luminescent probes. In this report, we studied details of toxicity mechanism of low doses of NaGdF₄-based fluorescent nanoparticles in activated RAW264.7, J774A.1 macrophages. These cell lines were specifically sensitive to the treatment with nanoparticles. Using nanoparticles of three different sizes, but with a uniform zeta potential (about −11 mV), we observed rapid uptake of NPs by the cells, resulting in the increased lysosomal compartment and subsequent superoxide induction along with a decrease in mitochondrial potential, indicating the impairment of mitochondrial homeostasis. At the molecular level, this led to upregulation of proapoptotic Bax and downregulation of anti-apoptotic Bcl-2, which triggered the apoptosis with phosphatidylserine externalization, caspase-3 activation and DNA fragmentation. We provide a time frame of the toxicity process by presenting data from different time points. These effects were present regardless of the size of nanoparticles. Moreover, despite the stability of NaGdF₄ nanoparticles at low pH, we identified cell acidification as an essential prerequisite of cytotoxic reaction using acidification inhibitors (NH₄Cl or Bafilomycin A1). Therefore, approaching the evaluation of the biocompatibility of such materials, one should keep in mind that toxicity could be revealed only in specific cells. On the other hand, designing gadolinium-doped NPs with increased resistance to harsh conditions of activated macrophage phagolysosomes should prevent NP decomposition, concurrent gadolinium release, and thus the elimination of its toxicity.

Disruption of IGF‑1R signaling by a novel quinazoline derivative, HMJ‑30, inhibits invasiveness and reverses epithelial-mesenchymal transition in osteosarcoma U‑2 OS cells

Osteosarcoma is the most common primary malignancy of the bone and is characterized by local invasion and distant metastasis. Over the past 20 years, long-term outcomes have reached a plateau even with aggressive therapy. Overexpression of insulin-like growth factor 1 receptor (IGF‑1R) is associated with tumor proliferation, invasion and migration in osteosarcoma. In the present study, our group developed a novel quinazoline derivative, 6-fluoro‑2-(3-fluorophenyl)-4-(cyanoanilino)quinazoline (HMJ‑30), in order to disrupt IGF‑1R signaling and tumor invasiveness in osteosarcoma U‑2 OS cells. Molecular modeling, immune-precipitation, western blotting and phosphorylated protein kinase sandwich ELISA assays were used to confirm this hypothesis. The results demonstrated that HMJ‑30 selectively targeted the ATP-binding site of IGF‑1R and inhibited its downstream phosphoinositide 3-kinase/protein kinase B, Ras/mitogen-activated protein kinase, and IκK/nuclear factor-κB signaling pathways in U‑2 OS cells. HMJ‑30 inhibited U‑2 OS cell invasion and migration and downregulated protein levels and activities of matrix metalloproteinase (MMP)‑2 and MMP-9. An increase in protein levels of tissue inhibitor of metalloproteinase (TIMP)‑1 and TIMP‑2 was also observed. Furthermore, HMJ‑30 caused U‑2 OS cells to aggregate and form tight clusters, and these cells were flattened, less elongated and displayed cobblestone-like shapes. There was an increase in epithelial markers and a decrease in mesenchymal markers, indicating that the cells underwent the reverse epithelial-mesenchymal transition (EMT) process. Overall, these results demonstrated the potential molecular mechanisms underlying the effects of HMJ‑30 on invasiveness and EMT in U‑2 OS cells, suggesting that this compound deserves further investigation as a potential anti-osteosarcoma drug.

YC-1 induces G0/G1 phase arrest and mitochondria-dependent apoptosis in cisplatin-resistant human oral cancer CAR cells

Oral cancer is a serious and fatal disease. Cisplatin is the first line of chemotherapeutic agent for oral cancer therapy. However, the development of drug resistance and severe side effects cause tremendous problems clinically. In this study, we investigated the pharmacologic mechanisms of YC-1 on cisplatin-resistant human oral cancer cell line, CAR. Our results indicated that YC-1 induced a concentration-dependent and time-dependent decrease in viability of CAR cells analyzed by MTT assay. Real-time image analysis of CAR cells by IncuCyte™ Kinetic Live Cell Imaging System demonstrated that YC-1 inhibited cell proliferation and reduced cell confluence in a time-dependent manner. Results from flow cytometric analysis revealed that YC-1 promoted G₀/G₁ phase arrest and provoked apoptosis in CAR cells. The effects of cell cycle arrest by YC-1 were further supported by up-regulation of p21 and down-regulation of cyclin A, D, E and CDK2 protein levels. TUNEL staining showed that YC-1 caused DNA fragmentation, a late stage feature of apoptosis. In addition, YC-1 increased the activities of caspase-9 and caspase-3, disrupted the mitochondrial membrane potential (AYm) and stimulated ROS production in CAR cells. The protein levels of cytochrome c, Bax and Bak were elevated while Bcl-2 protein expression was attenuated in YC-1-treated CAR cells. In summary, YC-1 suppressed the viability of cisplatin-resistant CAR cells through inhibiting cell proliferation, arresting cell cycle at G₀/G₁ phase and triggering mitochondria-mediated apoptosis. Our results provide evidences to support the potentially therapeutic application of YC-1 on fighting against drug resistant oral cancer in the future.