Pharmacological targeting of neurotensin response by diet-derived EGCG in macrophage-differentiated HL-60 promyelocytic leukemia cells

Abstract

The neurotensin (NTS)/neurotensin receptor (NTSR) axis in chronic B cell leukemia regulates B cell proliferation. We questioned whether a similar NTS/NTSR axis was functional in acute myeloid leukemia (AML), and to what extent it could become a pharmacological target for epigallocatechin-3-gallate (EGCG), a diet-derived polyphenol with chemopreventive properties. Analysis of NTS, NTSR1, NTSR2, and NTSR3 gene expression in AML patients using Kaplan-Meier plots highlighted NTSR3 as a poor clinical prognosis biomarker. EGCG was tested on NTSR3 function and gene/protein expression in undifferentiated and phorbol 12-myristate 13-acetate (PMA)-differentiated HL-60 cells, an acute promyelocytic leukemia subset cell line model from AML, which can differentiate into CD11bHigh/CD14Low adherent macrophages. We found that high level of gene, total protein, and cell surface expression of NTSR3 correlated with clinical samples of highly differentiated CD11b hematopoietic cells. Increased NTSR3 expression, NTS internalization, and matrix metalloproteinase-9 expression, was recapitulated in HL60-differentiated CD11bHigh macrophages, where chemotaxis in response to NTS was reduced through decreased Erk, MEK and Src signaling. EGCG prevented PMA-induced CD11b expression, NTS internalization and NTSR3-induced expression. Targeting of hematopoietic cell differentiation by EGCG could alter the NTS/NTSR3 signaling axis and possibly prevent the acquisition of an invasive phenotype.