Microarray analysis reveals distinct immune signatures in BCR-ABL positive and negative myeloproliferative neoplasms

Background: BCR-ABL mutation on the Philadelphia chromosome is the key driver of chronic myeloid leukemia (CML) pathogenesis. However, there are certain cases of myeloproliferative neoplasms (MPN) wherein no inherent driver mutation is detected resulting in clinical phenotype. It is important to identify key genes and pathways in driving the disease. The aim of the study was to use a gene-based omics approach to molecularly characterize these mutation-positive and negative cases to further strengthen diagnostics and precision medicine. Methods: A microarray profiling was done on CD34 positive cells isolated from two BCR-ABL positive and five BCR-ABL negative samples. JAK2V617F mutation testing was also done to rule out the presence of any other mutation in the latter group. The fold change cut-off was taken as +/- 1.5 with p <= 0.5 for significant genes. The gene network and pathway analysis were done using DAVID and STRING software. Results: The genes upregulated in BCR-ABL negative samples were shown to be involved in immune regulation, signal transduction and T- and B-cell signalling. The protein-protein interaction network of upregulated genes in these samples were enriched for various immunomodulatory genes such as HLADP, HLADQ, IL7R, CCR7, CD3 subtypes. These genes further formed a network with signal transduction genes such as LCK, FYN, RAG1, DOCK1, AKT3, SMAD3, LEF1. Conclusion: The results suggested a modulation of immune response genes and its subsequent effect on oncogenic signalling in BCR-ABL negative samples as compared to BCR-ABL positive samples. The protein network analysis was enriched for genes involved in Src, TGF-beta and PI3K-AKT pathway contributing to the proliferation of neoplastic clone.