Pb1797: the prognostic significance of bcat1 on npm1+flt3-itd+ aml patients and related molecular mechanisms

Topic: 3. Acute myeloid leukemia - Biology & Translational Research Background: Acute myeloid leukemia (AML) is a clonal malignant proliferative disease of non-lymphocytic origin in the hematopoietic system. FLT3-ITD mutations frequently co-occur with NPM1 mutations, and AML patients with NPM1 mutations at initial diagnosis (NPM1+) are classified in favorable group according to the 2017 version of the ELN AML guideline. They were further classified into favorable and intermediate risk groups according to the ratio of concomitant FLT3-ITD mutations, which are currently difficult to quantify accurately by conventional FLT3-ITD clinical testing methods and the optimal stratification boundaries are still controversial. Aims: To find novel biomarker in NPM1+FLT3-ITD+ AML patients for more precise stratification of these AML patients and explore the specific mechanisms by which FLT3-ITD interacts with novel biomarker and influences the occurrence and development of AML. Methods: This study included 248 NPM1+ AML patients who were initially diagnosed at the Peking University Institute of Hematology between 2015.01-2021.09, and the differentially expressed genes of NPM1+FLT3-ITD+ vs. NPM1+FLT3-ITD- groups were analyzed by Nanostring technology and bulk RNA- sequencing (RNA-seq), using bone marrow mononuclear cells. Differentially expressed genes between NPM1+FLT3-ITD+ vs. NPM1+FLT3-ITD- were also analyzed by mining the TCGA-AML, Beat-AML, GSE6891, GSE10358, and GSE15434 public datasets, taking the intersection and identifying the biomarker. The prognostic significance of the biomarker was analyzed in the Peking University Institute of Hematology. In AML cell lines Molm13 and MV411, which carry the FLT3-ITD mutation, the molecular mechanism of the interaction between the FLT3-ITD mutation and the biomarker was explored. Results: In the Nanostring cohort, RNA-Seq cohort, GSE6891, GSE10358, GSE15434, Beat-AML and TCGA-AML, a total of seven cohorts, BCAT1 was highly expressed in the NPM1+ FLT3-ITD+ group. In the RNA-Seq cohort and Nanostring cohort of Peking University Institute of Hematology, BCAT1 expression levels could effectively predict the prognosis of NPM1+ FLT3-ITD+AML patients, and the ability of BCAT1 transcript levels to predict the prognosis of NPM1+ITD+AML patients was superior to FLT3-ITD allelic ration. MV411 and MOLM13 cell lines were treated with AC220 respectively and BCAT1 expression was found to be significantly down-regulated at the mRNA level and the protein level. Analysis of the GSE106291 and GSE10078 dataset revealed that the expression of MYC was downregulated in both bone marrow-derived cells and tumor cell lines after knockdown of BCAT1 expression by lentivirus, respectively. It is suggested that BCAT1 may exerts pro-tumor biological functions by regulating the expression of MYC gene. Summary/Conclusion In this study, through multiple AML public database mining and multi-omics sequencing of clinical samples, we found that the BCAT1 gene was highly expressed in NPM1+ FLT3-ITD+ AML patients, and the prognosis of AML patients with BCAT1 high expression was poor, and the predictive ability of BCAT1 on the prognosis of NPM1+FLT3-ITD+ AML patients was better than the FLT3-ITD allelic ration, which can contribute to the precise stratification of this group of patients at the mRNA level. Cell line experiments in vitro revealed that the FLT3-ITD/BCAT1/MYC signaling pathway may play a biological function in promoting the development of AML in FLT3-ITD+ cell lines. FigurePrognostic significance of BCAT1 and FT3-ITD mutation ratio on the NPM1+ FLT3-ITD+ AML patients from Peking University Institute of Hematology RNA-Seq cohort. (A)BCAT1 expression level predicts OS; (B)FLT3-ITD mutation ratio predicts OS Keywords: AML, Flt3-ITD