The molecular signature of BCR::ABLP210 and BCR::ABLT315I in a Drosophila melanogaster chronic myeloid leukemia model

Chronic myeloid leukemia (CML) is a clonal hematopoietic stem cell disorder resulting from a balanced translocation leading to BCR::ABL1 oncogene with increased tyrosine kinase activity. Despite the advancements in the development of tyrosine kinase inhibitors (TKIs), the T315I gatekeeper point mutation in the BCR::ABL1 gene remains a challenge. We have previously reported in a Drosophila CML model an increased hemocyte count and disruption in sessile hemocyte patterns upon expression of BCR::ABL1p210 and BCR::ABL1T315I in the hemolymph. In this study, we performed RNA sequencing to determine if there is a distinct gene expression that distinguishes BCR::ABL1p210 and BCR::ABL1T315I. We identified six genes that were consistently upregulated in the fly CML model and validated in adult and pediatric CML patients and in a mouse cell line expressing BCR::ABL1T315I. This study provides a comprehensive analysis of gene signatures in BCR::ABL1p210 and BCR::ABL1T315I, laying the groundwork for targeted investigations into the role of these genes in CML pathogenesis.

Expression of chronic myeloid leukemia oncogenes BCR-ABL P210 and BCR-ABL T315I affect cellular and humoral innate immunity in Drosophila melanogaster

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm that results from a chromosomal translocation between chromosome 9 and chromosome 22. The resulting fusion gene ( BCR-ABL ) encodes a constitutively active BCR-ABL tyrosine kinase. Some mutations of this oncogene, especially the Threonine 315 to Isoleucine substitution of the ABL kinase is resistant to first and second-generation tyrosine kinase inhibitors (TKIs) conventionally used in CML therapy. We have previously validated a CML fruit fly model for drug screening using the adult fly compound eye. Here we expressed wild-type BCR-ABL ^P210 and mutated BCR-ABL ^T315I in Drosophila melanogaster hematopoietic system to understand the phenotypic consequences of this expression and its impact on innate immune pathways. Flies expressing both wild-type BCR-ABL^P210 and mutant BCR-ABL^T315I showed increased number of circulating hemocytes, disruption in sessile patterning of resident hemocytes, dysregulation in the humoral Toll, ImD, and JAK/STAT pathways at the mRNA level in both the 3 ^rd instar larva and adult stages. Of note, BCR-ABL^T315I flies presented more severe phenotypes and a higher deviation in humoral dysregulation than BCR -ABL^P210 flies pointing towards more complex oncogenic effect of this mutant which requires further investigation.