Dysregulation of iron homeostasis by TfR-1 renders EZH2 wild type diffuse large B-cell lymphoma resistance to EZH2 inhibition

EZH2: The roles in targeted therapy and mechanisms of resistance in breast cancer

Drug resistance presents a formidable challenge in the realm of breast cancer therapy. Accumulating evidence suggests that enhancer of zeste homolog 2 (EZH2), a component of the polycomb repressive complex 2 (PRC2), may serve as a key regulator in controlling drug resistance. EZH2 overexpression has been observed in breast cancer and many other malignancies, showing a strong correlation with poor outcomes. This review aims to summarize the mechanisms by which EZH2 regulates drug resistance, with a specific focus on breast cancer, in order to provide a comprehensive understanding of the underlying molecular processes. Additionally, we will discuss the current strategies and outcomes of targeting EZH2 using both single agents and combination therapies, with the goal of offering improved guidance for the clinical treatment of breast cancer patients who have developed drug resistance.

Ferroptosis mechanisms and its novel potential therapeutic targets for DLBCL

Diffuse large B-cell lymphoma (DLBCL), a heterogeneous lymphoid malignancy, poses a significant threat to human health. The standard therapeutic regimen for patients with DLBCL is rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), with a typical cure rate of 50-70%. However, some patients either relapse after complete remission (CR) or exhibit resistance to R-CHOP treatment. Therefore, novel therapeutic approaches are imperative for managing high-risk or refractory DLBCL. Ferroptosis is driven by iron-dependent phospholipid peroxidation, a process that relies on the transition metal iron, reactive oxygen species (ROS), and phospholipids containing polyunsaturated fatty acids-containing phospholipids (PUFA-PLs). Research indicates that ferroptosis is implicated in various carcinogenic and anticancer pathways. Several hematological disorders exhibit heightened sensitivity to cell death induced by ferroptosis. DLBCL cells, in particular, demonstrate an increased demand for iron and an upregulation in the expression of fatty acid synthase. Additionally, there exists a correlation between ferroptosis-associated genes and the prognosis of DLBCL. Therefore, ferroptosis may be a promising novel target for DLBCL therapy. In this review, we elucidate ferroptosis mechanisms, its role in DLBCL, and the potential therapeutic targets in DLBCL. This review offers novel insights into the application of ferroptosis in treatment strategies for DLBCL.

Regulation of EZH2 protein stability: new mechanisms, roles in tumorigenesis, and roads to the clinic

The importance of EZH2 as a key methyltransferase has been well documented theoretically. Practically, the first EZH2 inhibitor Tazemetostat (EPZ6438), was approved by FDA in 2020 and is used in clinic. However, for most solid tumors it is not as effective as desired and the scope of clinical indications is limited, suggesting that targeting its enzymatic activity may not be sufficient. Recent technologies focusing on the degradation of EZH2 protein have drawn attention due to their potential robust effects. This review focuses on the molecular mechanisms that regulate EZH2 protein stability via post-translational modifications (PTMs), mainly including ubiquitination, phosphorylation, and acetylation. In addition, we discuss recent advancements of multiple proteolysis targeting chimeras (PROTACs) strategies and the latest degraders that can downregulate EZH2 protein. We aim to highlight future directions to expand the application of novel EZH2 inhibitors by targeting both EZH2 enzymatic activity and protein stability.

Potential applications of ferroptosis inducers and regulatory molecules in hematological malignancy therapy

Ferroptosis, a novel form of iron-dependent cell death, has emerged as a potential avenue for promoting tumor cell death by causing cell membrane rupture and the accumulation of lipid peroxides (LPO) in the cell. Since its discovery in 2012, extensive research has been conducted to explore the mechanism of ferroptosis inducers, including erastin, sulfasalazine, and sorafenib. These compounds inhibit system XC-, while Ras-selective lethal small molecule 3 (RSL3) and FION2 specifically target GPX4 to promote ferroptosis. Therefore, targeting ferroptosis presents a promising therapeutic approach for malignant tumors. While the study of ferroptosis in solid tumors has made significant progress, there is limited information available on its role in hematological tumors. This review aims to summarize the molecular mechanisms of ferroptosis inducers and discuss their clinical applications in hematological malignancies. Furthermore, the identification of non-coding RNAs (ncRNAs) and genes that regulate key molecules in the ferroptosis pathway could provide new targets and establish a molecular theoretical foundation for exploring novel ferroptosis inducers in hematological malignancies.

Bone-targeting exosome nanoparticles activate Keap1 / Nrf2 / GPX4 signaling pathway to induce ferroptosis in osteosarcoma cells

BACKGROUND

In recent years, the development of BMSCs-derived exosomes (EXO) for the treatment of osteosarcoma (OS) is a safe and promising modality for OS treatment, which can effectively deliver drugs to tumor cells in vivo. However, the differences in the drugs carried, and the binding of EXOs to other organs limit their therapeutic efficacy. Therefore, improving the OS-targeting ability of BMSCs EXOs and developing new drugs is crucial for the clinical application of targeted therapy for OS.

RESULTS

In this study, we constructed a potential therapeutic nano platform by modifying BMSCs EXOs using the bone-targeting peptide SDSSD and encapsulated capreomycin (CAP) within a shell. These constructed nanoparticles (NPs) showed the ability of homologous targeting and bone-targeting exosomes (BT-EXO) significantly promotes cellular endocytosis in vitro and tumor accumulation in vivo. Furthermore, our results revealed that the constructed NPs induced ferroptosis in OS cells by prompting excessive accumulation of reactive oxygen species (ROS), Fe2+ aggregation, and lipid peroxidation and further identified the potential anticancer molecular mechanism of ferroptosis as transduced by the Keap1/Nrf2/GPX4 signaling pathway. Also, these constructed NP-directed ferroptosis showed significant inhibition of tumor growth in vivo with no significant side effects.

CONCLUSION

These results suggest that these constructed NPs have superior anticancer activity in mouse models of OS in vitro and in vivo, providing a new and promising strategy for combining ferroptosis-based chemotherapy with targeted therapy for OS.