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

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 implantation in the treatment of malignant tumors

Malignant tumors are major causes of morbidity and mortality in China. Despite advances in surgical, radiological, chemotherapeutic, molecular targeting, and immunotherapeutic treatments, patients with malignant tumors still have poor prognoses. Low-dose-rate brachytherapy, specifically 125I seed implantation, is beneficial because of its high local delivery dose and minimal damage to surrounding tissues. Consequently, it has gained increasing acceptance as a treatment modality for various malignant tumors. In this study, we explored the fundamental principles, clinical applications, and new technologies associated with 125I radioactive seed implantation.

V. J, Pal S, Nair BG, Kar R, Mishra N. Paraptosis: a unique cell death mode for targeting cancer

Programmed cell death (PCD) is the universal process that maintains cellular homeostasis and regulates all living systems' development, health and disease. Out of all, apoptosis is one of the major PCDs that was found to play a crucial role in many disease conditions, including cancer. The cancer cells acquire the ability to escape apoptotic cell death, thereby increasing their resistance towards current therapies. This issue has led to the need to search for alternate forms of programmed cell death mechanisms. Paraptosis is an alternative cell death pathway characterized by vacuolation and damage to the endoplasmic reticulum and mitochondria. Many natural compounds and metallic complexes have been reported to induce paraptosis in cancer cell lines. Since the morphological and biochemical features of paraptosis are much different from apoptosis and other alternate PCDs, it is crucial to understand the different modulators governing it. In this review, we have highlighted the factors that trigger paraptosis and the role of specific modulators in mediating this alternative cell death pathway. Recent findings include the role of paraptosis in inducing anti-tumour T-cell immunity and other immunogenic responses against cancer. A significant role played by paraptosis in cancer has also scaled its importance in knowing its mechanism. The study of paraptosis in xenograft mice, zebrafish model, 3D cultures, and novel paraptosis-based prognostic model for low-grade glioma patients have led to the broad aspect and its potential involvement in the field of cancer therapy. The co-occurrence of different modes of cell death with photodynamic therapy and other combinatorial treatments in the tumour microenvironment are also summarized here. Finally, the growth, challenges, and future perspectives of paraptosis research in cancer are discussed in this review. Understanding this unique PCD pathway would help to develop potential therapy and combat chemo-resistance in various cancer.

125I Radioactive Particles Drive Protective Autophagy in Hepatocellular Carcinoma by Upregulating ATG9B

BACKGROUND AND AIMS

¹²⁵I radioactive particles implantation have demonstrated efficacy in eradicating hepatocellular carcinoma (HCC). However, progressive resistance of HCC to ¹²⁵I radioactive particles has limited its wide clinical application.

METHODS

We investigated the cellular responses to ¹²⁵I radioactive particles treatment and autophagy-related 9B (ATG9B) silencing in HCC cell lines and Hep3B xenografted tumor model using Cell Counting Kit-8 reagent, western blotting, immunofluorescence, flow cytometry, transmission electron microscopy and immunohistochemistry.

RESULTS

In this study, we demonstrated that ¹²⁵I radioactive particles induced cell apoptosis and protective autophagy of HCC in vitro and in vivo. Inhibition of autophagy enhanced the radiosensitivity of HCC to ¹²⁵I radioactive particles. Moreover, ¹²⁵I radioactive particles induced autophagy by upregulating ATG9B, with increased expression level of LC3B and decreased expression level of p62. Furthermore, ATG9B silencing downregulated LC3B expression and upregulated p62 expression and enhanced radiosensitivity of HCC to ¹²⁵I radioactive particles in vitro and in vivo.

CONCLUSIONS

Inhibition of ATG9B enhanced the antitumor effects of ¹²⁵I particle radiation against HCC in vitro and in vivo. Our findings suggest that ¹²⁵I particle radiation plus chloroquine or/and the ATG9B inhibitor may be a novel therapeutic strategy for HCC.

A Novel Insight into Paraptosis-Related Classification and Signature in Lower-Grade Gliomas

Lower-grade gliomas (LGG) are the most common intracranial malignancies that readily evolve to high-grade gliomas and increase drug resistance. Paraptosis is defined as a nonapoptotic form of programmed cell death, which is gradually focused on patients with gliomas to develop treatment options. However, the specific role of paraptosis in LGG and its correlation is still vague. In this study, we first establish the novel paraptosis-based prognostic model for LGG patients. The relevant data of LGG patients were acquired from The Cancer Genome Atlas database, and we found that LGG patients could be divided into three different clusters based on paraptosis via consensus cluster analysis. Through least absolute shrinkage and selection operator regression analysis and multivariate Cox regression analysis, 10-paraptosis-related gene (PRG) signatures (CDK4, TNK2, DSTYK, CDKN3, CCR4, CASP9, HSPA5, RGR, LPAR1, and PDCD6IP) were identified to separate LGG patients into high- and low-risk subgroups successfully. The Kaplan-Meier analysis and time-dependent receiver-operating characteristic showed that the performances of predicting overall survival (OS) were dramatically high. The parallel results were reappeared and verified by using the Chinese Glioma Genome Atlas and Gene Expression Omnibus databases. Independent prognostic analysis and nomogram construction implied that risk scores could be considered the independent factor to predict OS. Enrichment analysis indicated that immune-related biological processes were generally enriched, and different immune statuses were highly infiltrated in high-risk group. We also confirmed the potential relationship of 10-PRG signatures and drug sensitivity of Food and Drug Administration-approved drugs. In summary, our findings provide a novel knowledge of paraptosis status and crucial direction to further explore the role of PRG signatures in LGG.

Iodine-125 Seeds Inhibit Carcinogenesis of Hepatocellular Carcinoma Cells by Suppressing Epithelial-Mesenchymal Transition via TGF-β1/Smad Signaling

To investigate the radioactive iodine-125 (I-125) seed on migrating and invading of hepatocellular carcinoma (HCC) cells and its mechanism, the irradiation of PLC and Huh7 cells was carried out with I-125 seeds in vitro. Cell counting kit 8 assay was employed to measure cell viability. Cell migration was evaluated by using wound-healing assay. Cell invasion was detected by Transwell assay; RT-PCR and Western blot were used for the detection of the mRNA and proteins of TGF-β1 signaling pathway-related genes. The viability of PLC and Huh7 cells declined in a dose-dependent manner with increasing irradiation from 0 Gy, 2 Gy, 4 Gy, and 6 Gy, to 8 Gy, respectively. The IC50 of PLC and Huh7 cells were 6.20 Gy and 5.39 Gy, respectively, after 24 h of irradiation. Migration and invasion abilities of I-125 group cells were greatly weakened (P < 0.05) comparing with the control group. According to the outcomes of RT-PCR and WB, I-125 seed irradiation significantly inhibited the mRNA and protein expression of N-cadherin, vimentin, TGF-β1, p-Smad2/3, and Snail. But the mRNA and protein expressions of E-cadherin were enhanced. Rescue experiment demonstrates that TGF-β1 activator could reverse the inhibitory effects of I-125 on invasion and migration of cells. The results of in vivo experiments further verified that the I-125 seeds can inhibit the proliferation and TGF-β1 of xenographed PLC cells. In conclusion, I-125 seeds restrain the invasion and migration of HCC cells by suppressing epithelial to mesenchymal transition, which may associate with the inhibition of the TGF-β1 signaling.

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.

Honokiol induces paraptosis-like cell death of acute promyelocytic leukemia via mTOR & MAPK signaling pathways activation

Acute promyelocytic leukemia (APL) is a blood system disease caused by the accumulation of a large number of immature blood cells in bone marrow. Although the introduction of all-trans retinoic acid (ATRA) and arsenic has reached a high level of complete remission rate and 5-year disease-free survival rate, the occurrence of various adverse reactions still severely affects the quality of life of patients. As a natural product, honokiol (HNK) has the advantages of low toxicity and high efficiency, and it is a potential drug for the treatment of cancer. Since cancer cells can escape apoptotic cell death through multiple adaptive mechanisms, HNK, a drug that induces cancer cell death in a nonapoptotic way, has attracted much interest. We found that HNK reduced the viability of human APL cell line (NB4 cells) by inducing paraptosis-like cell death. The process was accompanied by excessive reactive oxygen species (ROS), mitochondrial damage, endoplasmic reticulum stress, and increased microtubule-associated protein 1 light chain 3 (LC3) processing. The inactivation of proteasome activity was the main cause of misfolded and unfolded protein accumulation in endoplasmic reticulum, such as LC3II/I and p62. This phenomenon could be alleviated by adding cycloheximide (CHX), a protein synthesis inhibitor. We found that mTOR signaling pathway participated in paraptosis-like cell death induced by HNK in an autophagy-independent process. Moreover, the mitogen-activated protein kinase (MAPK) signaling pathway induced paraptosis of NB4 cells by promoting endoplasmic reticulum stress. In summary, these findings indicate that paraptosis may be a new way to treat APL, and provide novel insights into the potential mechanism of paraptosis-like cell death.