LSP1 promotes the progression of acute myelogenous leukemia by regulating KSR/ERK signaling pathway and cell migration

We aimed to investigate the role and mechanism of LSP1 in the progression of acute myelogenous leukemia. In this study, we established shLSP1 cell line to analyze the function of LSP1 in AML. We observed high expression of LSP1 in AML patients, whereas it showed no expression in normal adults. Furthermore, we found that LSP1 expression was associated with disease prognosis. Our results indicate that LSP1 plays a crucial role in mediating proliferation and survival of leukemia cells through the KSR/ERK signaling pathway. Additionally, LSP1 promotes cell chemotaxis and homing by enhancing cell adhesion and migration. We also discovered that LSP1 confers chemotactic ability to leukemia cells in vivo. Finally, our study identified 12 genes related to LSP1 in AML, which indicated poor survival outcome in AML patients and were enriched in Ras and cell adhesion signaling pathways. Our results revealed that the overexpression of LSP1 is related to the activation of the KSR/ERK signaling pathway, as well as cell adhesion and migration in AML patients. Reducing LSP1 expression impair AML progression, suggesting that LSP1 may serve as a potential drug therapy target for more effective treatment of AML.

FLI1 Regulates Histamine Decarboxylase Expression to Control Inflammation Signaling and Leukemia Progression

Aim

Histamine decarboxylase (HDC) catalyzes decarboxylation of histidine to generate histamine. This enzyme affects several biological processes including inflammation, allergy, asthma, and cancer, although the underlying mechanism is not fully understood. The present study provides a novel insight into the relationship between the transcription factor FLI1 and its downstream target HDC, and their effects on inflammation and leukemia progression.

Methods

Promoter analysis combined with chromatin immunoprecipitation (ChIp) was used to demonstrate binding of FLI1 to the promoter of HDC in leukemic cells. Western blotting and RT-qPCR were used to determine expression of HDC and allergy response genes, and lentivirus shRNA was used to knock-down target genes. Proliferation, cell cycle, apoptosis assays and molecular docking were used to determine the effect of HDC inhibitors in culture. An animal model of leukemia was employed to test the effect of HDC inhibitory compounds in vivo.

Results

Results presented herein demonstrate that FLI1 transcriptionally regulates HDC by direct binding to its promoter. Using genetic and pharmacological inhibition of HDC, or the addition of histamine, the enzymatic product of HDC, we show neither have a discernable effect on leukemic cell proliferation in culture. However, HDC controls several inflammatory genes including IL1B and CXCR2 that may influence leukemia progression in vivo through the tumor microenvironment. Indeed, diacerein, an IL1B inhibitor, strongly blocked Fli-1-induced leukemia in mice. In addition to allergy, FLI1 is shown to regulate genes associated with asthma such as IL1B, CPA3 and CXCR2. Toward treatment of these inflammatory conditions, epigallocatechin (EGC), a tea polyphenolic compound, is found strongly inhibit HDC independently of FLI1 and its downstream effector GATA2. Moreover, the HDC inhibitor, tetrandrine, suppressed HDC transcription by directly binding to and inhibiting the FLI1 DNA binding domain, and like other FLI1 inhibitors, tetrandrine strongly suppressed cell proliferation in culture and leukemia progression in vivo.

Conclusion

These results suggest a role for the transcription factor FLI1 in inflammation signaling and leukemia progression through HDC and point to the HDC pathway as potential therapeutics for FLI1-driven leukemia.

Association of Somatic Gene Mutations with Risk of Transformation into Acute Myeloid Leukemia in Patients with Myelodysplastic Syndrome: A Systematic Review and Meta-Analysis

OBJECTIVES

we aim to conduct a systematic review and meta-analysis in population of adult MDS patients to elucidate the role of these genes in AML transformation risk.

MATERIALS AND METHODS

The protocol for this systematic review and meta-analysis was registered in the international prospective register of systematic reviews (PROSPERO) with ID number of CRD42020218581. Systematic literature search was conducted by all authors up to October 2021 on: (1) PubMed, (2) EBSCOhost, (3) Scopus, (4) JSTOR, and (5) grey literatures. Hand-searching for relevant articles was also conducted. The following keywords with their synonyms and combinations using Boolean operators were applied to all database: "myelodysplastic syndrome", SRSF2", "SF3B1", "U2AF1", "ASXL1", "DNMT3A", "TET2", "IDH1", "IDH2", "RUNX1", "acute myeloid leukemia progression", and "leukemia free survival". Outcome was measured using hazard ratio (HR).

RESULTS

We identified 14 articles to be used for this systematic review and meta-analysis. There was no statistically significant difference in AML transformation risk between U2AF1 mutant and U2AF1 wildtype MDS patients (HR: 1.41; 95% CI: 0.95-2.07, p=0.08, I2=0%). Pooled HR showed that patients with SRSF2 mutation had higher risk of AML transformation (HR 2.62; 95% CI: 1.54-4.45; p= .0004; I2= 55%). The pooled HR for SF3B1 was 0.48 (95% CI: 0.22-1.06, p=0.07, I2=55%). Mutations of TET2, ASXL1, and EZH2 were not associated with AML transformation. Meanwhile, DNMT3A mutations were associated with AML transformation with pooled HR of 2.73 (95% CI: 1.43-5.21; p= 0.08; I2: 67%). The pooled HR for IDH genes was smaller (HR: 2.92; 95%CI: 1.21-7.06; p=0.02; I2:65%). Patients with RUNX1 mutation were associated with AML transformation (HR: 1.85; 95%CI: 1.11-3.09; p=0.02; I2:38%).

CONCLUSION

Based from our analyses, MDS patients with mutations of SRSF2, DNMT3A, IDH, and RUNX1 have higher hazard ratio for AML transformation.

Stage-Specific Human Induced Pluripotent Stem Cells Map the Progression of Myeloid Transformation to Transplantable Leukemia

Myeloid malignancy is increasingly viewed as a disease spectrum, comprising hematopoietic disorders that extend across a phenotypic continuum ranging from clonal hematopoiesis to myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). In this study, we derived a collection of induced pluripotent stem cell (iPSC) lines capturing a range of disease stages encompassing preleukemia, low-risk MDS, high-risk MDS, and secondary AML. Upon their differentiation, we found hematopoietic phenotypes of graded severity and/or stage specificity that together delineate a phenotypic roadmap of disease progression culminating in serially transplantable leukemia. We also show that disease stage transitions, both reversal and progression, can be modeled in this system using genetic correction or introduction of mutations via CRISPR/Cas9 and that this iPSC-based approach can be used to uncover disease-stage-specific responses to drugs. Our study therefore provides insight into the cellular events demarcating the initiation and progression of myeloid transformation and a new platform for testing genetic and pharmacological interventions.