Combined Strategy of Radioactive 125I Seeds and Salinomycin for Enhanced Glioma Chemo-radiotherapy: Evidences for ROS-Mediated Apoptosis and Signaling Crosstalk

Carfilzomib promotes Iodine-125 seed radiation-induced apoptosis, paraptosis, and ferroptosis in esophageal squamous cell carcinoma by aggravating endoplasmic reticulum stress

Iodine-125 (125I) seed brachytherapy has been applied to treat various malignant tumors such as esophageal cancer, however, radioresistance can reduce its efficacy. Endoplasmic reticulum stress (ERS) and subsequent unfolded protein response (UPR) is one of the core mechanisms of 125I seed radiation-induced cell death, thus aggravating ERS has been considered a promising sensitization strategy. Herein, we show that combination therapy of an irreversible proteasome inhibitor carfilzomib (CFZ) and 125I seed radiation displayed strong anti-tumor effect on esophageal squamous cell carcinoma (ESCC). Mechanistically, ERS and UPR regulated multiple cell death modalities induced by the combination therapy, including apoptosis, paraptosis, and ferroptosis. 125I seed radiation induced reactive oxygen species (ROS) production, DNA damage, p53 activation, and apoptosis. CFZ promoted ROS production, and augmented 125I seed radiation-induced apoptosis via the mitochondrial pathway, which was mediated by the UPR-C/EBP homologous protein (CHOP) pathway and was independent of the p53 pathway. CFZ enhanced 125I seed radiation-induced intracellular Ca2+ overload, protein ubiquitination, ERS, and UPR, consequently promoting paraptosis. 125I seed radiation induced accumulation of intracellular Fe2+ and lipid peroxides but upregulated the expression of ferroptosis inhibitors, SLC7A11 and glutathione peroxidase 4 (GPX4). The combination therapy promoted ferroptosis by enhancing the accumulation of intracellular Fe2+ and downregulating GPX4 expression. The mouse experiment demonstrated that CFZ can promote the efficacy of 125I seed radiation with good tolerance. Our findings suggest that combination therapy of 125I seed radiation and CFZ is associated with multiple cell death modalities and may serve as a promising therapeutic strategy for ESCC.

Mechanistic insights into 125I seed implantation therapy for Cholangiocarcinoma: focus on ROS-Mediated apoptosis and the role of GPX2

OBJECTIVES

Cholangiocarcinoma (CCA) is a rare tumor with a poor prognosis and poses significant therapeutic challenges. Herein, we investigated the mechanism of efficacy of 125I seed implantation therapy in CCA, focusing on the induction of reactive oxygen species (ROS)-mediated apoptosis and the involvement of glutathione peroxidase 2 (GPX2).

MATERIALS AND METHODS

Human cholangiocarcinoma cell lines QBC939 and RBE were purchased for in vitro studies. In vivo studies were performed using a rabbit VX2 CCA model. Apoptosis and proliferation were detected by TUNEL staining and clone formation, respectively. ROS generation was detected by dihydroethidium staining. Histological evaluation was performed by hematoxylin and eosin staining. Protein expression was determined by Western blotting and immunohistochemistry.

RESULTS

Our results demonstrate that 125I seeds effectively inhibited tumor growth in the rabbit VX2 tumor model and promoted the apoptosis of CCA cells in vitro in a dose-dependent manner. Molecular analyses indicate a marked increase in reactive oxygen species (ROS) levels following treatment with 125I seeds, suggesting the involvement of ROS-mediated apoptosis in the therapeutic mechanism. Furthermore, the downregulation of glutathione peroxidase 2 (GPX2) was observed, indicating its potential role in modulating ROS-mediated apoptosis in CCA.

CONCLUSION

125I seed implantation therapy exerts therapeutic effects on CCA by inducing ROS-mediated apoptosis. The downregulation of GPX2 may contribute to enhanced ROS accumulation and apoptotic cell death. These findings provide mechanistic insights into the therapeutic potential of 125I seed implantation for CCA and highlight ROS-mediated apoptosis and GPX2 regulation as promising targets for further investigation and therapeutic intervention in this malignancy.

Iodine-125 seed inhibits proliferation and promotes apoptosis of cholangiocarcinoma cells by inducing the ROS/p53 axis

With advances in radioactive particle implantation in clinical practice, Iodine-125 (125I) seed brachytherapy has emerged as a promising treatment for cholangiocarcinoma (CCA), showing good prognosis; however, the underlying molecular mechanism of the therapeutic effect of 125I seed is unclear. To study the effects of 125I seed on the proliferation and apoptosis of CCA cells. CCA cell lines, RBE and HCCC-9810, were treated with reactive oxygen species (ROS) scavenger acetylcysteine (NAC) or the p53 functional inhibitor, pifithrin-α hydrobromide (PFTα). Cell counting kit-8 (CCK-8) assay, 5-bromo-2-deoxy-uridine (BrdU) staining, and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay and flow cytometry assay were performed to test the radiation-sensitivity of 125I seed toward CCA cells at different radiation doses (0.4 mCi and 0.8 mCi). 2,7-dichlorofluorescein diacetate (DCF-DA) assay, real-time quantitative polymerase chain reaction (RT-qPCR), and western blot analysis were performed to assess the effect of 125I seed on the ROS/p53 axis. A dose-dependent inhibitory effect of 125I seeds on the proliferation of CCA cells was observed. The 125I seed promoted apoptosis of CCA cells and induced the activation of the ROS/p53 pathway in a dose-dependent manner. NAC or PFTα treatment effectively reversed the stimulatory effect of 125I seed on the proliferation of CCA cells. NAC or PFTα suppressed apoptosis and p53 protein expression induced by the 125I seed. 125I seed can inhibit cell growth mainly through the apoptotic pathway. The mechanism may involve the activation of p53 and its downstream apoptotic pathway by up-regulating the level of ROS in cells.

Natural and synthetic compounds for glioma treatment based on ROS-mediated strategy

Glioma is the most frequent and most malignant tumor of the central nervous system (CNS)，accounting for about 50% of all CNS tumor and approximately 80% of the malignant primary tumors in the CNS. Patients with glioma benefit from surgical resection, chemo- and radio-therapy. However these therapeutical strategies do not significantly improve the prognosis, nor increase survival rates owing to restricted drug contribution in the CNS and to the malignant characteristics of glioma. Reactive oxygen species (ROS) are important oxygen-containing molecules that regulate tumorigenesis and tumor progression. When ROS accumulates to cytotoxic levels, this can lead to anti-tumor effects. Multiple chemicals used as therapeutic strategies are based on this mechanism. They regulate intracellular ROS levels directly or indirectly, resulting in the inability of glioma cells to adapt to the damage induced by these substances. In the current review, we summarize the natural products, synthetic compounds and interdisciplinary techniques used for the treatment of glioma. Their possible molecular mechanisms are also presented. Some of them are also used as sensitizers: they modulate ROS levels to improve the outcomes of chemo- and radio-therapy. In addition, we summarize some new targets upstream or downstream of ROS to provide ideas for developing new anti-glioma therapies.

Gold nanoparticles enhances radiosensitivity in glioma cells by inhibiting TRAF6/NF-κB induced CCL2 expression

Gliomas are inherently difficult to treat by radiotherapy because glioma cells become radioresistant over time. However, combining radiotherapy with a radiosensitizer could be an effective strategy to mitigate the radioresistance of glioma cells. Gold nanoparticles (AuNPs) have emerged as a promising nanomaterial for cancer therapy, but little is known about whether AuNPs and X-ray radiation have cytotoxic synergistic effects against tumors. In this study, we found that the combination of AuNPs and X-ray irradiation significantly reduced the viabilities, as well as the migration and invasion, of glioma cells. Mechanistically, we observed that the AuNPs inhibited radiation-induced CCL2 expression by inhibiting the TRAF6/NF-κB pathway, which likely manifested the synergistic therapeutic effect between the AuNPs and X-ray radiation. The AuNPs also re-sensitized radioresistant glioma cells by inhibiting CCL2 expression. These results were also observed in another tumor cell line with a different molecular pattern, indicating that the underlying mechanism may be ubiquitous through cancer cells. Lastly, using the glioma mouse model, we observed that AuNPs significantly reduced tumor growth in the presence of X-ray radiation compared to radiotherapy alone.

Tumor oxygenation nanoliposome synergistic hypoxia-inducible-factor-1 inhibitor enhanced Iodine-125 seed brachytherapy for esophageal cancer

Iodine-125 (¹²⁵I) brachytherapy has become one of the most effective palliative treatment options for advanced esophageal cancer. However, resistance toward ¹²⁵I brachytherapy caused by pre-existing tumor hypoxia and hypoxia-inducible factor 1 (HIF-1) signaling pathway activation represents a significant limitation in esophageal cancer treatment. To circumvent these problems, herein, we proposed an innovative strategy to alleviate radioresistance of brachytherapy by co-encapsulating catalase (CAT) and HIF-1 inhibitor-acriflavine (ACF) into the hydrophilic cavities of liposome, termed as "ACF-CAT@Lipo". Under overexpressed H₂O₂ stimulation in the tumor region, the fabricated ACF-CAT@Lipo can generate an amount of O₂ and alleviate tumor hypoxia in vitro and in vivo. Furthermore, cooperating with ACF, the expression of hypoxia-related protein (e.g. HIF-1α, VEGF, MMP-2) are obviously decreased. Importantly, the copious oxygenation and the significant inhibition expression of HIF-1α can further improve the radiosensitivity of ¹²⁵I brachytherapy and finally realize the eradication of esophageal cancer in vivo. The oxygen enrichment and HIF-1 inhibition function of ACF-CAT@Lipo provides a new strategy to overcome the brachytherapy resistance of esophageal cancer therapy.

Potential targets and treatments affect oxidative stress in gliomas: An overview of molecular mechanisms

Oxidative stress refers to the imbalance between oxidation and antioxidant activity in the body. Oxygen is reduced by electrons as part of normal metabolism leading to the formation of various reactive oxygen species (ROS). ROS are the main cause of oxidative stress and can be assessed through direct detection. Oxidative stress is a double-edged phenomenon in that it has protective mechanisms that help to destroy bacteria and pathogens, however, increased ROS accumulation can lead to host cell apoptosis and damage. Glioma is one of the most common malignant tumors of the central nervous system and is characterized by changes in the redox state. Therapeutic regimens still encounter multiple obstacles and challenges. Glioma occurrence is related to increased free radical levels and decreased antioxidant defense responses. Oxidative stress is particularly important in the pathogenesis of gliomas, indicating that antioxidant therapy may be a means of treating tumors. This review evaluates oxidative stress and its effects on gliomas, describes the potential targets and therapeutic drugs in detail, and clarifies the effects of radiotherapy and chemotherapy on oxidative stress. These data may provide a reference for the development of precise therapeutic regimes of gliomas based on oxidative stress.

Administration of Iodine-125 Seeds Promotes Apoptosis in Cholangiocarcinoma through the PI3K/Akt Pathway

Purpose. We aimed to examine the effects of 125I seeds on the gene expression of Bcl-2, Bax, and PI3K/Akt pathway components in cholangiocarcinoma cells. Methods. In vitro, human cholangiocarcinoma RBE cells were treated with 125I seeds (0.39 mCi or 0.85 mCi) for 72 h, 120 h, and 168 h. Cell proliferation and apoptosis were assessed. The expression of Bcl-2 and Bax was detected by RT-PCR, and Western blotting was carried out to explore changes in Akt activity. Result. 125I seeds inhibited the proliferation of RBE cells. The apoptosis rate of the RBE cells in the low-activity group was significantly higher than that in the high-activity group at 120 h and 168 h, while no difference was found between the two groups at 72 h. After 120 h of culture, the gene expression of Bcl-2 and Bax decreased in both groups, the ratio of $\text{Bcl}-2/\text{Bax}$ in the low-activity group decreased, and the PI3K/Akt signaling pathway was inhibited in both groups. Conclusion. 125I seeds affect the proliferation and apoptosis of cholangiocarcinoma cells in a dose-dependent manner. The therapeutic effect of low-activity 125I seeds on cancer cells may be better. 125I seed brachytherapy may promote the apoptosis of cholangiocarcinoma cells by inhibiting the PI3K/Akt signaling pathway and regulating the $\text{Bcl}-2/\text{Bax}$ ratio.

Iodine‑125 seed radiation induces ROS‑mediated apoptosis, autophagy and paraptosis in human esophageal squamous cell carcinoma cells

Iodine-125 (¹²⁵I) seed brachytherapy has been proven to be a safe and effective treatment for advanced esophageal cancer; however, the mechanisms underlying its actions are not completely understood. In the present study, the anti-cancer mechanisms of ¹²⁵I seed radiation in human esophageal squamous cell carcinoma (ESCC) cells (Eca-109 and KYSE-150) were determined, with a particular focus on the mode of cell death. The results showed that ¹²⁵I seed radiation significantly inhibited cell proliferation, and induced DNA damage and G2/M cell cycle arrest in both ESCC cell lines. ¹²⁵I seed radiation induced cell death through both apoptosis and paraptosis. Eca-109 cells were primarily killed by inducing caspase-dependent apoptosis, with 6 Gy radiation resulting in the largest response. KYSE-150 cells were primarily killed by inducing paraptosis, which is characterized by extensive cytoplasmic vacuolation. ¹²⁵I seed radiation induced autophagic flux in both ESCC cell lines, and autophagy inhibition by 3-methyladenine enhanced radiosensitivity. Furthermore ¹²⁵I seed radiation induced increased production of reactive oxygen species (ROS) in both ESCC cell lines. Treatment with an ROS scavenger significantly attenuated the effects of ¹²⁵I seed radiation on endoplasmic reticulum stress, autophagy, apoptosis, paraptotic vacuoles and reduced cell viability. In vivo experiments showed that ¹²⁵I seed brachytherapy induced ROS generation, initiated cell apoptosis and potential paraptosis, and inhibited cell proliferation and tumor growth. In summary, the results demonstrate that in ESCC cells, ¹²⁵I seed radiation induces cell death through both apoptosis and paraptosis; and at the same time initiates protective autophagy. Additionally, ¹²⁵I seed radiation-induced apoptosis, paraptosis and autophagy was considerably mediated by ROS.

Salinomycin and its derivatives - A new class of multiple-targeted "magic bullets"

The history of drug development clearly shows the scale of painstaking effort leading to a finished product - a highly biologically active agent that would be at the same time no or little toxic to human organism. Moreover, the aim of modern drug discovery can move from "one-molecule one-target" concept to more promising "one-molecule multiple-targets" one, particularly in the context of effective fight against cancer and other complex diseases. Gratifyingly, natural compounds are excellent source of potential drug leads. One of such promising naturally-occurring drug candidates is a polyether ionophore - salinomycin (SAL). This compound should be identified as multi-target agent for two reasons. Firstly, SAL combines a broad spectrum of bioactivity, including antibacterial, antifungal, antiviral, antiparasitic and anticancer activity, with high selectivity of action, proving its significant therapeutic potential. Secondly, the multimodal mechanism of action of SAL has been shown to be related to its interactions with multiple molecular targets and signalling pathways that are synergistic for achieving a therapeutic anticancer effect. On the other hand, according to the Paul Ehrlich's "magic bullet" concept, invariably inspiring the scientists working on design of novel target-selective molecules, a very interesting direction of research is rational chemical modification of SAL. Importantly, many of SAL derivatives have been found to be more promising as chemotherapeutics than the native structure. This concise review article is focused both on the possible role of SAL and its selected analogues in future antimicrobial and/or cancer therapy, and on the potential use of SAL as a new class of multiple-targeted "magic bullet" because of its multimodal mechanism of action.