Search

Abstract Leukemia stem cells (LSCs) are recognized as the root cause of leukemia initiation, relapse, and drug resistance. Lipid species are highly abundant and essential component of human cells, which often changed in tumor microenvironment. LSCs remodel lipid metabolism to sustain the stemness. However, there is no useful lipid related biomarker has been approved for clinical practice in AML prediction and treatment. Here, we constructed and verified fatty acid metabolism-related risk score (LFMRS) model based on TCGA database via a series of bioinformatics analysis, univariate COX regression analysis, and multivariate COX regression analysis, and found that the LFMRS model could be an independent risk factor and predict the survival time of AML patients combined with age. Moreover, we revealed that Galectin-1 (LGALS1, the key gene of LFMRS) was highly expressed in LSCs and associated with poor prognosis of AML patients, and LGALS1 repression inhibited AML cell and LSC proliferation, enhanced cell apoptosis, and decreased lipid accumulation in vitro. LGALS1 repression curbed AML progression, lipid accumulation, and CD8+ T and NK cell counts in vivo. Our study sheds light on the roles of LFMRS (especially LGALS1) model in AML, and provides information that may help clinicians improve patient prognosis and develop personalized treatment regimens for AML.

Abstract Acute myeloid leukemia (AML) is a rapidly progressing and often fatal hematopoietic malignancy. Venetoclax (VEN), a recent FDA-approved BCL-2 selective inhibitor, has high initial response rates in elderly AML patients, but the majority of patients eventually acquire resistance. Multiple studies have demonstrated that the female sex is associated with better outcomes in patients with AML, which are predominantly attributed to estrogen signaling. As a novel membrane estrogen receptor, G protein-coupled estrogen receptor (GPER)-mediated-rapid estrogen effects have attracted considerable attention. However, whether targeting GPER enhances the antileukemic activity of VEN is unknown. In this study, we first demonstrated that GPER expression was dramatically reduced in AML cells owing to promoter hypermethylation. Furthermore, pharmacological activation of GPER by G-1 combined with VEN resulted in synergistic antileukemic activity in vitro and in vivo. Mechanistically, G-1/VEN combination synergistically triggered concurrent mitochondria-related apoptosis and gasdermin E (GSDME)-dependent pyroptosis by activating p38-MAPK/myeloid cell leukemia 1 (MCL-1) axis. Importantly, leukemic pyroptosis heightened CD8+ T cell immune function by releasing interleukin (IL)-1β/18 into the tumor microenvironment. Our study corroborates that GPER activation shows a synergistic antileukemic effect with VEN, making it a promising therapeutic regimen for AML.

Abstract Background Acute myeloid leukemia (AML) with mutated nucleophosmin (NPM1), which displays a distinct long noncoding RNA (lncRNA) expression profile, has been defined as a unique subgroup in the new classification of myeloid neoplasms. However, the biological roles of key lncRNAs in the development of NPM1-mutated AML are currently unclear. Here, we aimed to investigate the functional and mechanistic roles of the lncRNA HOTAIRM1 in NPM1-mutated AML. Methods The expression of HOTAIRM1 was analyzed with a public database and further determined by qRT-PCR in NPM1-mutated AML samples and cell lines. The cause of upregulated HOTAIRM1 expression was investigated by luciferase reporter, chromatin immunoprecipitation and ubiquitination assays. The functional role of HOTAIRM1 in autophagy and proliferation was evaluated using western blot analysis, immunofluorescence staining, a Cell Counting Kit-8 (CCK-8) assay, a 5-ethynyl-2′-deoxyuridine (EdU) incorporation assay, flow cytometric analyses and animal studies. The action mechanism of HOTAIRM1 was explored through RNA fluorescence in situ hybridization, RNA pulldown and RNA immunoprecipitation assays. Results HOTAIRM1 was highly expressed in NPM1-mutated AML. High HOTAIRM1 expression was induced in part by mutant NPM1 via KLF5-dependent transcriptional regulation. Importantly, HOTAIRM1 promoted autophagy and proliferation both in vitro and in vivo. Mechanistic investigations demonstrated that nuclear HOTAIRM1 promoted EGR1 degradation by serving as a scaffold to facilitate MDM2-EGR1 complex formation, while cytoplasmic HOTAIRM1 acted as a sponge for miR-152-3p to increase ULK3 expression. Conclusions Taken together, our findings identify two oncogenic regulatory axes in NPM1-mutated AML centered on HOTAIRM1: one involving EGR1 and MDM2 in the nucleus and the other involving the miR-152-3p/ULK3 axis in the cytoplasm. Our study indicates that HOTAIRM1 may be a promising therapeutic target for this distinct leukemia subtype.

Exosomal long non-coding RNAs (lncRNAs) have emerged as a cell-free biomarker for clinical evaluation of cancers. However, the potential clinical applications of exosomal lncRNAs in acute myeloid leukemia (AML) remain unclear. Herein, we attempted to identify plasma exosomal lncRNAs as prospective biomarkers for AML. In this study, plasma exosomes were first successfully extracted from AML patients and healthy donors (HD). Subsequently, the downregulated plasma exosomal lncRNAs (LINC00265, LINC00467, and UCA1) and the upregulated plasma exosomal lncRNA (SNHG1) were identified in AML patients (n=65) compared to HD (n=20). Notably, individual exosomal LINC00265, LINC00467, UCA1, or SNHG1 had a capability for discriminating AML patients from HD, and their combination displayed better efficiency. Furthermore, exosomal LINC00265 and LINC00467 were increased expressed in patients achieving complete remission after chemotherapy. Importantly, there was upregulation of exosomal LINC00265 and downregulation of exosomal SNHG1 upon allogeneic hematopoietic stem cell transplantation. Additionally, these lncRNAs were high stability in plasma exosomes. Exosomal LINC00265, LINC00467, UCA1, and SNHG1 may act as promising cell-free biomarkers for AML diagnosis and treatment monitoring and provide a new frontier of liquid biopsy for this type of cancer.

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy characterized by multiple cytogenetic and molecular abnormalities, with a very poor prognosis. Current treatments for AML often fail to eliminate leukemic stem cells (LSCs), which perpetuate the disease. LSCs exhibit a unique metabolic profile, especially dependent on oxidative phosphorylation (OXPHOS) for energy production. Whereas, normal hematopoietic stem cells (HSCs) and leukemic blasts rely on glycolysis for adenosine triphosphate (ATP) production. Thus, understanding the regulation of OXPHOS in LSCs may offer effective targets for developing clinical therapies in AML. This review summarizes these studies with a focus on the regulation of the electron transport chain (ETC) and tricarboxylic acid (TCA) cycle in OXPHOS and discusses potential therapies for eliminating LSCs.

Acute myeloid leukemia (AML) with nucleophosmin 1 (NPM1) mutations exhibits distinct biological and clinical features, accounting for approximately one-third of AML. Recently, the N6-methyladenosine (m6A) RNA modification has emerged as a new epigenetic modification to contribute to tumorigenesis and development. However, there is limited knowledge on the role of m6A modifications in NPM1-mutated AML. In this study, the decreased m6A level was first detected and high expression of fat mass and obesity-associated protein (FTO) was responsible for the m6A suppression in NPM1-mutated AML. FTO upregulation was partially induced by NPM1 mutation type A (NPM1-mA) through impeding the proteasome pathway. Importantly, FTO promoted leukemic cell survival by facilitating cell cycle and inhibiting cell apoptosis. Mechanistic investigations demonstrated that FTO depended on its m6A RNA demethylase activity to activate PDGFRB/ERK signaling axis. Our findings indicate that FTO-mediated m6A demethylation plays an oncogenic role in NPM1-mutated AML and provide a new layer of epigenetic insight for future treatments of this distinctly leukemic entity.

Abstract Acute myeloid leukaemia (AML) carrying nucleophosmin (NPM1) mutations has been defined as a distinct entity of acute leukaemia. Despite remarkable improvements in diagnosis and treatment, the long‐term outcomes for this entity remain unsatisfactory. Emerging evidence suggests that leukaemia, similar to other malignant diseases, employs various mechanisms to evade killing by immune cells. However, the mechanism of immune escape in NPM1‐mutated AML remains unknown. In this study, both serum and leukemic cells from patients with NPM1‐mutated AML impaired the immune function of CD8+ T cells in a co‐culture system. Mechanistically, leukemic cells secreted miR‐19a‐3p into the tumour microenvironment (TME) via small extracellular vesicles (sEVs), which was controlled by the NPM1‐mutated protein/CCCTC‐binding factor (CTCF)/poly (A)‐binding protein cytoplasmic 1 (PABPC1) signalling axis. sEV‐related miR‐19a‐3p was internalized by CD8+ T cells and directly repressed the expression of solute‐carrier family 6 member 8 (SLC6A8; a creatine‐specific transporter) to inhibit creatine import. Decreased creatine levels can reduce ATP production and impair CD8+ T cell immune function, leading to immune escape by leukemic cells. In summary, leukemic cell‐derived sEV‐related miR‐19a‐3p confers immunosuppression to CD8+ T cells by targeting SLC6A8‐mediated creatine import, indicating that sEV‐related miR‐19a‐3p might be a promising therapeutic target for NPM1‐mutated AML.

Abstract Cancer‐associated fibroblasts (CAFs) as a predominant cell component in the tumour microenvironment (TME) play an essential role in tumour progression. Our earlier studies revealed oxidized ATM activation in breast CAFs, which is independent of DNA double‐strand breaks (DSBs). Oxidized ATM has been found to serve as a redox sensor to maintain cellular redox homeostasis. However, whether and how oxidized ATM in breast CAFs regulates breast cancer progression remains poorly understood. In this study, we found that oxidized ATM phosphorylates BNIP3 to induce autophagosome accumulation and exosome release from hypoxic breast CAFs. Inhibition of oxidized ATM kinase by KU60019 (a small‐molecule inhibitor of activated ATM) or shRNA‐mediated knockdown of endogenous ATM or BNIP3 blocks autophagy and exosome release from hypoxic CAFs. We also show that oxidized ATM phosphorylates ATP6V1G1, a core proton pump in maintaining lysosomal acidification, leading to lysosomal dysfunction and autophagosome fusion with multi‐vesicular bodies (MVB) but not lysosomes to facilitate exosome release. Furthermore, autophagy‐associated GPR64 is enriched in hypoxic CAFs‐derived exosomes, which stimulates the non‐canonical NF‐κB signalling to upregulate MMP9 and IL‐8 in recipient breast cancer cells, enabling cancer cells to acquire enhanced invasive abilities. Collectively, these results provide novel insights into the role of stromal CAFs in promoting tumour progression and reveal a new function of oxidized ATM in regulating autophagy and exosome release.

Background: Cancer-associated fibroblasts (CAFs) are the predominant residents in the breast tumor microenvironment. In our work, we found activation of DNA damage-independent ATM (oxidized ATM), enhanced glycolysis and aberrant metabolism-associated gene expressions in breast CAFs. Nevertheless, whether and how oxidized ATM regulates the glycolytic activity of CAFs keep in unveil. Recently, a reverse Warburg effect was observed in tumor tissues, in which host cells (such as CAFs, PSCs) in the tumor microenvironment have been found to “fuel” the cancer cells via metabolites transfer. However, the molecular mechanisms of the metabolites from stromal cells playing a role to the progression of cancer cells remain to be determined. Methods: Oxidized ATM activation in stromal CAFs was assessed by western blotting and immunofluorescence. The increased glycolytic ability of CAFs was validated by measurements of OCR and ECAR and detections of glucose consumption and lactate production. Kinase assay and western blotting were performed to confirm the phosphorylation of GLUT1. The membrane location of phosphorylated GLUT1 was determined by biotin pull-down assay and immunofluorescence staining. The regulation of PKM2 through oxidized ATM was evaluated by western blots. In addition, the impact of lactate derived from hypoxic CAFs on cancer cell invasion was investigated both in vitro (transwell assays, western blots) and in vivo (orthotopic xenografts). Findings: Hypoxia-induced oxidized ATM promotes glycolytic activity of CAFs by phosphorylating GLUT1 at S490 and increasing PKM2 expression. Moreover, lactate derived from hypoxic CAFs, acting as a metabolic coupling between CAFs and breast cancer cells, promotes breast cancer cell invasion by activating the TGFβ1/p38 MAPK/MMP2/9 signaling axis and fueling the mitochondrial activity in cancer cells. Interpretation: Our work shows that oxidized ATM-mediated glycolysis enhancement in hypoxic stromal fibroblasts plays an essential role in cancer cell invasion and metastasis and may implicate oxidized ATM as a target for breast tumor treatment. Fund: This research was supported by National Natural Science Foundation of China. Keywords: CAFs, Oxidized-ATM, Hypoxia, GLUT1, PKM2(PYKM2)

Hepatocellular carcinoma (HCC) is an aggressive malignancy with a poor prognosis. Effective biomarkers and specific therapeutic targets for HCC are therefore urgently needed. G protein-coupled estrogen receptor (GPER) plays a crucial role in numerous cancer types; however, its functions in HCC require further exploration. In the present study, we found a remarkable difference in GPER staining between tumor tissue (100/141, 70.9%) and matched non-tumor tissue (27/30, 90.0%). Compared with the GPER-negative patients, the GPER-positive patients with HCC were closely associated with female sex, negative hepatitis B surface antigen, small tumor size, low serum alpha fetoprotein level, and longer overall survival. Treatment with GPER-specific agonist G1 led to the sustained and transient activation of the EGFR/ERK and EGFR/AKT signaling pathways, respectively, in the HCC cell lines HCCLM3 and SMMC-7721, which express high levels of GPER. Interestingly, G1-induced EGFR/ERK signaling, rather than EGFR/AKT signaling mediated by GPER, was involved in decreasing cell viability by blocking cell cycle progression, thereby promoting apoptosis and inhibiting cell growth. Clinical analysis indicated that simultaneous high expression of GPER and phosphorylated-ERK (p-ERK) predicted improved prognosis for HCC. Finally, the activation of GPER/ERK signaling remarkably suppressed tumor growth in an HCC xenograft model, and this result was consistent with the in vitro data. Our findings suggest that specific activation of the GPER/ERK axis may serve as a novel tumor-suppressive mechanism and that this axis could be a therapeutic target for HCC.

Abstract Cancer stem cells (CSCs) are considered the roots of cancer metastasis and recurrence (CSCs), due in part to their self‐renewal and therapy resistance properties. However, the underlying mechanisms for the regulation of CSC stemness are poorly understood. Recently, increasing evidence shows that long non‐coding RNAs (lncRNAs) are critical regulators for cancer cell function in various malignancies including breast cancer, but how lncRNAs regulate the function of breast cancer stem cells (BCSCs) remains to be determined. Herein, using lncRNA/mRNA microarray assays, a novel lncRNA (named lnc030) is identified, which is highly expressed in BCSCs in vitro and in vivo, as a pivotal regulator in maintaining BCSC stemness and promoting tumorigenesis. Mechanistically, lnc030 cooperates with poly(rC) binding protein 2(PCBP2) to stabilize squalene epoxidase (SQLE) mRNA, resulting in an increase of cholesterol synthesis. The increased cholesterol in turn actives PI3K/Akt signaling, which governs BCSC stemness. In summary, these findings demonstrate that a new, lnc030‐based mechanism for regulating cholesterol synthesis and stemness properties of BCSCs. The lnc030‐SQLE‐cholesterol synthesis pathway may serve as an effective therapeutic target for BCSC elimination and breast cancer treatment.

Background/Aims: The ataxia-telangiectasia mutated (ATM) protein kinase is critical for the maintenance of genomic stability and acts as tumor suppressor. Although evidence shows that a DNA damage-independent ATM (oxidized ATM) may be involved in cancer progression, the underlying mechanism is still unclear. Methods: Immunohistochemistry, immunofluorescence and western blotting were applied to detect the levels of oxidized ATM. Transwell assay was used to detect the cell migration and invasion abilities in different treatments. Quantitative phosphoproteome analysis was performed using hypoxic BT549 cells, in the presence or absence of Ku60019, a specific inhibitor of ATM kinase. The phosphorylated cortactin, the target protein of oxidized ATM, was confirmed by immunoprecipitation-western blots and in vitro kinase assay. The functions of phosphorylated cortactin were studied by specific short hairpin RNA, site-directed mutation, transwell assay, and actin polymerization assay. Results: Enhanced oxidized ATM proteins were present not only in the advanced and invasive breast tumor tissues but also malignant hypoxic breast cancer cells, in the absence of DNA damage. Loss of ATM expression or inhibiting oxidized ATM kinase activity reduced breast cancer cell migration and invasion. Using quantitative phosphoproteomics approach, 333 oxidized ATM target proteins were identified, some of these proteins govern key signaling associated with gap junction, focal adhesion, actin cytoskeleton rearrangement. Cortactin, one of the biggest changed phospho-protein, is a novel oxidized ATM-dependent target in response to hypoxia. Mechanically, we reveal that hypoxia-activated ATM can enhance the binding affinity of cortactin with Arp2/3 complex by phosphorylating cortactin at serine 113, and as a result, in favor of breast cancer cell migration and invasion. Conclusion: Oxidized ATM can phosphorylate cortactin at serine 113, playing a critical role in promoting breast tumor cell mobility and invasion via actin polymerization.