1015 - Coupled effect of a miR-155 deficiency and hypoxia conditions leads to the upregulation of SLC2A1 (GLUT1), SLC2A3 (GLUT3) and EGLN1 genes in the leukemic B-cells

Hypoxia represents one of the key factors that stimulate the growth of leukemic cells in their niche. Hypoxia forces the leukemic cells to reprogram their original transcriptome, miRNome, and metabolome. It is still not fully known how the microRNAs (miRNAs) / mRNAs coupling enables the emergence of a leukemic state. Generally, miRNAs regulate practically all cells' biological processes and play a crucial role in leukemia development and progression.
In the present study, we aimed to uncover the impact of hsa-miR-155-5p (miR-155, MIR155HG) on the metabolism, proliferation, and mRNA/miRNA network of human chronic lymphocytic leukemia cells (CLL) in hypoxia conditions. In this project, we used the human MEC-1 cell line, as a model of CLL, where we deleted mature miR-155 with the CRISPR/Cas9 tool. However, hypoxia increases the proliferation of MEC-1 cells; the miR-155 deficiency overall reduces cell proliferation. The miR-155 deficiency under hypoxia condition was accompanied by a level-up of apoptosis.
Besides the common hypoxia-related genes (HIF1α, EGLN1, VHL, HK1, and HK2) we also examined glucose-transporters genes SLC2A1 (GLUT1) and SLC2A3 (GLUT3) by qRT-PCR. The hypoxic, miR-155 deficient MEC-1 cells significantly raised the expression of EGLN1, GLUT3, and GLUT1 genes, which points out possible novel targets of miR-155 in CLL. In addition to this, we detected considerable overexpression of hsa-miR-210-5p, a well-known hypoxamiRNA, in MEC-1 cells in hypoxia. Subsequently, the qRT-PCR and the metabolic assays showed the significant influence of miR-155 on glucose and lactate metabolism. Decreased glucose uptake and increased lactate support our hypothesis that miR-155 deficiency and hypoxia transform leukemic cell metabolism.
To conclude, the coupled effect of miR-155 deficiency and hypoxia affects glucose and lactate metabolism that stimulates the expression of GLUT1, GLUT3, and EGLN1 genes in MEC-1 CLL cells. Effective inhibition of key metabolites in the leukemic cells could be one of the novel options in the current treatment of CLL.