Coagulation FXIII-a Protein Expression Defines Three Novel Sub-Populations in Pediatric B-Cell Progenitor Acute Lymphoblastic Leukemia Characterized By Distinct Gene Expression Signatures

Background Leukemic B-cell precursor (BCP) lymphoblasts were identified as a novel expression site for coagulation factor XIII subunit A (FXIII-A). FXIII-A expression determined by flow cytometry (FC) exhibited characteristically distinct expression patterns in subgroups of lymphoblasts. The FXIII-A negative subgroup was significantly associated with the ‘B-other’ genetic category and had an unfavorable disease outcome. Methods RNA was extracted from bone marrow lymphoblasts of 42 pediatric patients with BCP-acute lymphoblastic leukemia (ALL). FXIII-A expression was determined by multiparameter FC. Genetic diagnosis was based on conventional cytogenetic method and fluorescence in situ hybridization. Affymetrix GeneChip Human Primeview array was used to analyze global expression pattern of 28869 well-annotated genes. Microarray data were analyzed by Genespring GX14.9.1 software. Gene Ontology (GO) analysis was performed using Cytoscape 3.4.0 software with ClueGO application. Selected differentially expressed (DE) genes were validated by RT-Q-PCR. Results We demonstrated, for the first time, the general expression of F13A1 gene in pediatric BCP-ALL samples. The intensity of F13A1 expression corresponded to the expression of FXIII-A protein, as determined by FC. We observed three well-defined categories of FXIII-A protein expression: FXIII-A negative (80% FXIII-A positive blasts). The intensity of the FXIII-A expression increased continuously, which excluded the existence of a distinct FXIII-A negative and a FXIII-A bright subpopulation within the FXIII-A dim subgroup (Image 1/A). These three subgroups defined three characteristic and distinct gene expression signatures detected by Affymetrix oligonucleotide microarrays. There were 26 DE genes found when comparing the FXIII-A negative with the FXIII-A bright subgroup. The FXIII-A dim vs. bright comparison resulted in 155 DE genes and there were 88 DE genes identified between the FXIII-A negative and dim subgroups (Image 1/B). Expression of F13A1 gene was detected and readily validated by RT-Q-PCR in every sample. Intensity of gene expression; however, was characteristically different among samples of the three different FXIII-A protein expression subgroups with an increasing intensity in terms of relative fold-changes measured by RT-Q-PCR from the FXIII-A negative, through dim to bright subgroups. We selected 13/