INTRODUCTION: SLIT-ROBO is a ligand-receptor family of neuronal guidance cues 
that has been involved in pathological and physiological angiogenesis. SLIT-ROBO 
expression is altered in many tumours. However, no data exist about the role of 
the whole family in acute myelogenous myeloid leukemia (AML).
PURPOSE: Herein, we assessed the expression of all SLIT-ROBO family in bone 
marrow (BM) biopsy of AML patients and control group on both protein and RNA 
levels.
METHODS: The paraffin-embedded tissue blocks were subjected to 
immunohistochemistry for SLIT1, SLIT2, SLIT3, ROBO1, ROBO2, ROBO3, and ROBO4. 
Microvessel density (MVD) was evaluated by CD34 immunohistochemistry. An in 
silico analysis using The Cancer Genome Atlas data repository was conducted for 
assessment of RNA level.
RESULTS: Acute myeloid leukemia patients were generally high expressers of ROBO1 
and ROBO2 compared to the controls (p < 0.0001, p < 0.001, respectively). In 
contrast, low expression of SLIT1, SLIT2, and SLIT3 ligands has been noted more 
commonly in AML than in control BM samples (p < 0.0001, p = 0.003, and 
p = 0.001, respectively). ROBO4 expression correlated with MVD. The in silico 
analysis showed a poor prognostic value of high ROBO3 and low SLIT2 RNA levels 
(p = 0.0003 and p = 0.0008, respectively), as well as high ROBO3 and ROBO4 RNA 
levels in cytogenetic poor risk groups of patients (p = 0.0029 and p = 0.0003, 
respectively).
CONCLUSIONS: These data indicate that SLIT-ROBO family members play a role in 
the biology of AML. Low expression of SLIT in BM of AML patients may suggest its 
expression alterations in AML. Increased expression of ROBO1 and ROBO2 in AML 
patients suggests their participation in AML pathogenesis.