NOTCH activation promotes glycosyltransferase expression in human myeloid leukemia cells

NOTCH signaling diversely regulates the growth of acute myeloid leukemia (AML) cells. It is known that glycosylation of NOTCH receptors modulates NOTCH activation. However, little is known about glycosylation of NOTCH in AML cells. We examined the effects of ligand-induced NOTCH activation on the expression of NOTCHmodifying glycosyltransferases in two AML cell lines, THP-1 and TMD7. The cells were stimulated with recombinant NOTCH ligands JAGGED1 and DELTA1, and subjected to immunoblot analysis to evaluate the expression levels of glycosyltransferases. Ligand stimulation promoted the expression of POFUT1, LFNG, MFNG, RFNG, GXYLT1, GXYLT2, and XXYLT1 in THP-1 cells, and that of RFNG and GXYLT1 in TMD7 cells. We found that NOTCH activation promoted the expression of several glycosyltransferases in AML cells. This suggests that NOTCH activation modulates its sensitivity to NOTCH ligands by increased glycosylation of NOTCH receptors in AML cells. Further investigation is needed to elucidate its biological significance

FOXP3 knockdown inhibits the proliferation and reduces NOTCH1 expression of T cell acute lymphoblastic leukemia cells

Abstract Objective Forkhead box P3 (FOXP3) is a master transcriptional factor of regulatory T-cells (Tregs). Recent studies have shown that FOXP3 is associated with growth inhibition of cancer cells. However, the role of FOXP3 in acute T-lymphoblastic leukemia (T-ALL) cells is not known. It was also reported that NOTCH signaling promoted the expression of FOXP3 in Tregs. However, the effect of FOXP3 on NOTCH expression in T-ALL cells is little known. Therefore, we examined the effect of FOXP3 knockdown on the proliferation of T-ALL cells and NOTCH1 signaling. Results Two T-ALL cell lines Jurkat and KOPT-K1, harboring activating NOTCH1 mutations, were transfected with small interfering RNA against FOXP3. Cell growth was assessed with a colorimetric assay and morphology was observed under a microscope. FOXP3 knockdown significantly reduced cell growth and induced morphological changes suggesting apoptosis. Quantitative polymerase chain reaction revealed that FOXP3 knockdown caused the downregulation of mRNA expression of NOTCH1 and HES1. These findings suggest that FOXP3 supports the growth of T-ALL cells although this can not be generalized because we examined only two cell lines. The observed growth suppression can be partly due to the downregulation of NOTCH1 signaling. FOXP3 may be a potential therapeutic target in T-ALL