Targeting IFN-γ-inducible lysosomal thiol reductase overcomes chemoresistance in AML through regulating the ROS-mediated mitochondrial damage

Susceptibility of acute myeloid leukemia cells to ferroptosis and evasion strategies

Acute myeloid leukemia (AML) is a highly aggressive hematologic malignancy with a 5-year survival rate of less than 30%. Continuous updating of diagnostic and therapeutic strategies has not been effective in improving the clinical benefit of AML. AML cells are prone to iron metabolism imbalance due to their unique pathological characteristics, and ferroptosis is a novel cell death mode that is dominated by three cellular biological processes: iron metabolism, oxidative stress and lipid metabolism. An in-depth exploration of the unique ferroptosis mechanism in AML can provide new insights for the diagnosis and treatment of this disease. This study summarizes recent studies on ferroptosis in AML cells and suggests that the metabolic characteristics, gene mutation patterns, and dependence on mitochondria of AML cells greatly increase their susceptibility to ferroptosis. In addition, this study suggests that AML cells can establish a variety of strategies to evade ferroptosis to maintain their survival during the process of occurrence and development, and summarizes the related drugs targeting ferroptosis pathway in AML treatment, which provides development directions for the subsequent mechanism research and clinical treatment of AML.

Chemoresistance in acute myeloid leukemia: An alternative single-cell RNA sequencing approach

Our previous study demonstrated that myc, mitochondrial oxidative phosphorylation, mTOR, and stemness are independently responsible for chemoresistance in acute myeloid leukemia (AML) cells. This study aimed to identify potential mechanisms of chemoresistance of the "7 + 3" induction in AML by using a single-cell RNA sequencing (scRNA-seq) approach. In the present study, 13 untreated patients with de novo AML were enrolled and stratified into two groups: complete remission (CR; n = 8) and non-CR (n = 5). Single-cell RNA sequencing was used to analyze genetic profiles of 28,950 AML cells from these patients; results were validated using a previously published bulk RNA-seq dataset. Our study results showed chemoresistant AML cells had premature accumulation during early hematopoiesis. Hematopoietic stem cell-like cells from the non-CR group expressed more leukemic stem cell markers (CD9, CD82, IL3RA, and IL1RAP) than those from the CR group. Chemoresistant progenitor cells had impaired myeloid differentiation owing to early arrest of hematopoiesis. Notably, AML cells analyzed by scRNA-seq and bulk RNA-seq harbored a comparable myeloid lineage cell fraction, which internally validated our results. Using the TCGA database, our analysis demonstrated that patients with AML with higher expression of chemoresistant genetic markers (IL3RA and IL1RAP) had a worse overall survival (p < 0.01 for IL3RA; p < 0.05 for IL1RAP). In conclusion, AML cells responsive and resistant to the "7 + 3" induction were derived from a diverse cancerous hematopoietic stem cell population, as indicated by the specific genetic biomarkers obtained using scRNA-seq approach. Furthermore, arrest of hematopoiesis was shown to occur earlier in chemoresistant AML cells, furthering the current understanding of chemoresistance in AML.

Drug therapy for myocarditis induced by immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs), including cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed cell death 1 (PD-1), and its ligand 1 (PD-L1), have improved the survival in multiple types of cancers; however, ICIs may cause cardiovascular toxicity. Although rare, ICI-mediated cardiotoxicity is an extremely serious complication with a relatively high mortality. In this review, we discuss the underlying mechanism and clinical manifestations of cardiovascular toxicity induced by ICIs. According to previous studies, multiple signaling pathways are involved in myocarditis induced by ICIs. Further, we summarize the clinical trials of drugs for the treatment of ICI-associated myocarditis. Although these drugs have shown the beneficial effects of alleviating cardiac function and reducing mortality rates, their efficacy is not optimal. Finally, we discuss the therapeutic potential of some novel compounds as well as the underlying mechanisms of their action.

Comprehensive analysis of ECHDC3 as a potential biomarker and therapeutic target for acute myeloid leukemia: Bioinformatic analysis and experimental verification

Background

Enoyl-CoA hydratase domain containing 3 (ECHDC3) increased in CD34+ progenitor cells of acute myeloid leukemia (AML) cells after chemotherapy. However, the prognostic significance and function of ECHDC3 in AML remain to be clarified.

Methods

In the training cohort, 24 AML (non-acute promyelocytic leukemia, APL) patients were enrolled in Peking University People’s Hospital and tested for ECHDC3 in enriched CD34+ cells at diagnosis. In the validation set, 351 bone marrow RNA-seq data of non-APL AML were obtained by two independent online datasets (TCGA-LAML and BEAT-AML). LASSO regression model was conducted to a new prediction model of ECHDC3-related genes. In addition, the ECHDC3 signature was further explored by GO, KEGG, GSEA, and immuno-infiltration analysis. By RNA interference, the function of ECHDC3 in mitochondrial DNA (mt-DNA) transcriptome and chemoresistance was further explored, and the GSE52919 database re-verified the ECHDC3 chemoresistance feature.

Results

By Kaplan-Meier analysis, patients with ECHDC3high demonstrated inferior overall survival (OS) compared to those with ECHDC3low both in the training (2-year OS, 55.6% vs. 100%, p = 0.011) and validation cohorts (5-year OS, 9.6% vs. 24.3%, p = 0.002). In addition, ECHDC3high predicted inferior OS in the subgroup of patients with ELN 2017 intermediated (int) risk (5-year OS, 9.5% vs. 26.3%, p = 0.039) or FLT3+NPM1− adverse (adv) risk (4-year OS, 6.4% vs. 31.8%, p = 0.003). In multivariate analysis, ECHDC3 was an independent risk factor of inferior OS (HR 1.159, 95% CI 1.013–1.326, p = 0.032). In the prediction model combining ECHDC3 and nine selected genes (RPS6KL1, RELL2, FAM64A, SPATS2L, MEIS3P1, CDCP1, CD276, IL1R2, and OLFML2A) by Lasso regression, patients with high risk showed inferior 5-year OS (9.3% vs. 23.5%, p &lt; 0.001). Bioinformatic analysis suggested that ECHDC3 alters the bone marrow microenvironment by inducing NK, resting mast cell, and monocyte differentiation. Knocking down ECHDC3 in AML cells by RNAi promoted the death of leukemia cells with cytarabine and doxorubicin.

Conclusion

These bioinformatic analyses and experimental verification indicated that high ECHDC3 expression might be a poor prognostic biomarker for non-APL AML, which might be a potential target for reverting chemoresistance.

Lysosomes in Stem Cell Quiescence: A Potential Therapeutic Target in Acute Myeloid Leukemia

Lysosomes are cellular organelles that regulate essential biological processes such as cellular homeostasis, development, and aging. They are primarily connected to the degradation/recycling of cellular macromolecules and participate in cellular trafficking, nutritional signaling, energy metabolism, and immune regulation. Therefore, lysosomes connect cellular metabolism and signaling pathways. Lysosome's involvement in the critical biological processes has rekindled clinical interest towards this organelle for treating various diseases, including cancer. Recent research advancements have demonstrated that lysosomes also regulate the maintenance and hemostasis of hematopoietic stem cells (HSCs), which play a critical role in the progression of acute myeloid leukemia (AML) and other types of cancer. Lysosomes regulate both HSCs' metabolic networks and identity transition. AML is a lethal type of blood cancer with a poor prognosis that is particularly associated with aging. Although the genetic landscape of AML has been extensively described, only a few targeted therapies have been produced, warranting the need for further research. This review summarizes the functions and importance of targeting lysosomes in AML, while highlighting the significance of lysosomes in HSCs maintenance.