Single-cell sequencing unveils T-cell characteristic in acute myeloid leukemia.

Acute myeloid leukemia (AML) presents as a remarkably heterogeneous disease, and the intricate role of various T cell subtypes, including T helper (Th) cells and regulatory T (Treg) cells, in immune dysregulation and the promotion of leukemia cell proliferation and survival is not yet fully understood. In this study, we conducted a comparative analysis of transcriptome profiles in T cells derived from bone marrow samples of three leukemia patients, both before and after treatment, as well as from a relapse sample. This analysis was facilitated through the utilization of single-cell RNA sequencing. The T cell population was subcategorized into CD4 + T cells and CD8 + T cells. Intriguingly, the composition of CD8 + T cells exhibited a relatively stable pattern before and after treatment, while a substantial difference in composition was observed in CD4 + T cells, notably in Th17 and Treg cell populations. Pseudotime trajectory analysis of CD4 + T cell clusters provided further insights into the augmented transition between Th17-like and Treg cells in AML. This transition was characterized by changes in the expression of key genes, including STAT3, CCR6, IL23R, FOXP3, and CTLA4, along their developmental path. An increased cell-to-cell interaction between AML blast cells and all types of T cells appeared to contribute to the restoration of normal T cell proportions. Notably, the LGALS9-CD45 and LGALS9-CD44 pathways emerged as pivotal interactions between blast cells and Treg cells. Our findings unveil an imbalanced differentiation pattern in CD4 + T cells and elucidate the immunosuppressive profiles linked to leukemia cells, thereby enhancing our understanding of CD4 + T cell functionality in the context of AML.

G-CSF upregulates the expression of aquaporin-9 through CEBPB to enhance the cytotoxic activity of arsenic trioxide to acute myeloid leukemia cells.

BACKGROUND: Arsenic trioxide (ATO) is highly effective in acute promyelocytic leukemia (APL) patients, but it fails to show satisfactory efficacy in other acute myeloid leukemia (AML) patients with non-APL subtypes. Different from the APL cells, most non-APL AML cells express low levels of the ATO transporter Aquaporin-9 (AQP9) protein, making them less sensitive to ATO treatment. Recently, we found that granulocyte colony stimulating factor (G-CSF) can upregulate the expression of AQP9. We hypothesized that the pretreatment with G-CSF may enhance the antitumor effect of ATO in non-APL AML cells. In addition, we aimed to elucidate the underlying mechanisms by which G-CSF upregulates the expression of AQP9. METHODS: Non-APL AML cell lines including THP-1 and HL-60 were pretreated with or without G-CSF (100 ng/ml) for 24 h, followed by the treatment with ATO (2 µM) for 48 h. Cell morphology was observed under the microscope after Wright-Giemsa staining. Flow cytometry was performed to evaluate the cell apoptosis levels. The intracellular concentrations of ATO were determined by atomic fluorescence spectrometry. The mRNA and protein expression were respectively measured by quantitative reverse transcription PCR (RT-qPCR) and western blotting. Target genes were knocked down by transfection with small interfering RNA (siRNA), or overexpressed by transfection with overexpression plasmids. The cell line derived xenograft mouse model was established to confirm the results of the in vitro experiments. RESULTS: Compared with using ATO alone, the combination of G-CSF with ATO induced the cell apoptosis more dramatically. G-CSF upregulated the expression of AQP9 and enhanced the intracellular concentrations of ATO in AML cells. When AQP9 was overexpressed, it markedly enhanced the cytotoxic activity of ATO. On the other hand, when AQP9 was knocked down, it profoundly attenuated the combinational effect. Moreover, we found that the upregulation of AQP9 by G-CSF depends on the transcription factor CCAAT enhancer binding protein beta (CEBPB). We also demonstrated that the combination of G-CSF and ATO significantly inhibited tumor growth in the xenograft mouse model. CONCLUSIONS: The combination of G-CSF and ATO may be a potential therapeutic strategy for AML patients.

Homoharringtonine Synergized with Gilteritinib Results in the Downregulation of Myeloid Cell Leukemia-1 by Upregulating UBE2L6 in FLT3-ITD-Mutant Acute Myeloid (Leukemia) Cell Lines.

FMS-like tyrosine kinase 3 (FLT3) mutant acute myeloid leukemia (AML) occurs in approximately 30% of all AML patients and still has a poor prognosis. This study is directed to investigate gilteritinib in combination with homoharringtonine (HHT) on FLT3-ITD-mutant AML cell lines. In our study, we found that cell proliferation was dramatically suppressed by the combination of gilteritinib and HHT. This combination therapy decreased the mitochondrial membrane potential, finally inducing apoptosis. We demonstrated that gilteritinib downregulated the expression of FLT3 and downstream signaling, further decreased the mRNA level of myeloid cell leukemia-1 (Mcl-1). HHT and combination therapy could upregulate UBE2L6, which induced the degradation of Mcl-1 via ubiquitin-proteasome system. Knockdown of UBE2L6 could protect Mcl-1 from deprivation through the ubiquitin-proteasome system. These findings may provide a novel theoretical basis for the treatment of AML patients with FLT3-ITD mutations.

Synergistic effect of oridonin and a PI3K/mTOR inhibitor on the non-germinal center B cell-like subtype of diffuse large B cell lymphoma.

We demonstrate the synergistic antitumor effect of oridonin and the PI3K/mTOR inhibitor NVP-BEZ235 on the non-germinal center B cell-like subtype of diffuse large B cell lymphoma (non-GCB DLBCL) both in vitro and in vivo. The underlying mechanism may be multifunctional, involving apoptosis, AKT/mTOR and NF-kB inactivation, and ROS-mediated DNA damage response. Our findings pave the way for a new potential treatment option for non-GCB DLBCL with the combination of oridonin and NVP-BEZ235.

Reactive oxygen species mediate oridonin-induced apoptosis through DNA damage response and activation of JNK pathway in diffuse large B cell lymphoma.

This study investigated the cytotoxic effect of oridonin (ORI), a diterpenoid isolated from Rabdosia rubescens, in human diffuse large B cell lymphoma (DLBCL) in vitro and in vivo and the potential molecular mechanisms for ORI-induced cell apoptosis. ORI treatment caused reactive oxygen species (ROS)-mediated oxidative DNA damage response (DDR) and the c-Jun N-terminal kinase (JNK) pathway activation, leading to an induction of intrinsic apoptosis. ROS abolition blocked ORI-induced apoptosis and attenuated the expression of phospho-histone H2AX and phospho-JNK, indicating that ROS-mediated DNA damage and JNK pathway activation were involved in ORI-induced apoptosis. The systemic administration of ORI suppressed the growth of human DLBCL xenografts without showing significant toxicity. These findings suggest that ORI may have promising therapeutic application in DLBCL.

Combination of rituximab and mammalian target of rapamycin inhibitor everolimus (RAD001) in diffuse large B-cell lymphoma.

Abstract We evaluated the efficacy of the anti-CD20 monoclonal antibody rituximab in combination with the mammalian target of rapamycin (mTOR) inhibitor everolimus for treating diffuse large B-cell lymphoma (DLBCL). The combination of rituximab and everolimus was more effective for inhibiting cell growth compared with single-agent therapy. An increase in G0/G1 cell cycle arrest and an increased population of cells in apoptosis were observed in the combination treatment group. The addition of rituximab reduced the overexpression of p-AKT caused by the negative feedback loop of everolimus and had an enhanced effect on inhibition of mTOR signaling, thus providing a rationale for this synergistic effect. Furthermore, combination treatment was also more effective than treatment with either agent alone for inhibiting the growth of DLBCL xenografts. Our study provides preclinical evidence and a theoretical basis for combination therapy with rituximab and everolimus in DLBCL.