Vinorelbine Activates Downstream Targets of Notch Signaling on Huvec Cells
Authors: L. Mavroeidis, H. Sheldon, E. Briasoulis, M. Marselos, P. Pappas, A. Harris
Journal: Annals of Oncology (2013)

Vinorelbine is a vinca alkaloid1 and is able to inhibit endothelial cell function through binding to microtubules2. We show that 10 nM vinorelbine inhibits HUVEC tube formation (0.3 compared to control, ± 0.2, p < 0.05) on matrigel assay and sprouting from HUVEC spheroids (0.1 compared to control, ± 0.007, p < 0.005).Notch signaling activation also suppresses angiogenic sprouting3 and we investig ated this as a possible mechanism of vinorelbine action in addition to the direct anti-microtubular action that the vinca alkaloids possess.10 nM VRL increased the mRNA levels of the target genes of Notch, HEY1 (2.24 fold, ± 0.6, p < 0.05) and HES1 (1.42 fold, ± 0.2, p < 0.05) in 12 h without increasing NICD (Notch intracellular domain) protein expression but 100 nM of the gamma-secretase inhibitor DBZ did not inhibit this effect significantly.NF-kB is another transcription factor that regulates Notch signaling in NIH-3T3 and 293T cells as determined by cotransfection assays4. We found in HUVEC that 10 nM vinorelbine caused translocation of NF-kB p65 and NF-kB p50 to the nucleus after 1 h treatment but 10 µ&Mgr; of the IKK inhibitor iii BMS 345541 (blocks NF-kB activation) did not inhibit the vinorelbine effect on HES1 and HEY1 mRNA although it reduced the dll4 (delta like 4) mRNA levels (50 fold, ±0.003, p < 0.0005). c-JUN also regulates target genes of Notch signaling5. 10 nM vinorelbine caused JNK kinase phosphorylation in 30 min but 10 µ&Mgr; of the JNK inhibitor ii did not block the increase on HES1 and HEY1 mRNA after 12 h treatment when the maximum increase of HES1 and HEY1 occurs.ConclusionsVinorelbine can activate target genes of Notch without direct action on NICD expression. This effect cannot be attributed to the already known pathways that regulate Notch, NF-kB and c-JUN. There was however a striking effect of NF-kB inhibition on Dll4 expression. Crosstalk with other pathways deserves further investigation. Vinorelbine is a vinca alkaloid1 and is able to inhibit endothelial cell function through binding to microtubules2. We show that 10 nM vinorelbine inhibits HUVEC tube formation (0.3 compared to control, ± 0.2, p < 0.05) on matrigel assay and sprouting from HUVEC spheroids (0.1 compared to control, ± 0.007, p < 0.005). Notch signaling activation also suppresses angiogenic sprouting3 and we investig ated this as a possible mechanism of vinorelbine action in addition to the direct anti-microtubular action that the vinca alkaloids possess. 10 nM VRL increased the mRNA levels of the target genes of Notch, HEY1 (2.24 fold, ± 0.6, p < 0.05) and HES1 (1.42 fold, ± 0.2, p < 0.05) in 12 h without increasing NICD (Notch intracellular domain) protein expression but 100 nM of the gamma-secretase inhibitor DBZ did not inhibit this effect significantly. NF-kB is another transcription factor that regulates Notch signaling in NIH-3T3 and 293T cells as determined by cotransfection assays4. We found in HUVEC that 10 nM vinorelbine caused translocation of NF-kB p65 and NF-kB p50 to the nucleus after 1 h treatment but 10 µ&Mgr; of the IKK inhibitor iii BMS 345541 (blocks NF-kB activation) did not inhibit the vinorelbine effect on HES1 and HEY1 mRNA although it reduced the dll4 (delta like 4) mRNA levels (50 fold, ±0.003, p < 0.0005). c-JUN also regulates target genes of Notch signaling5. 10 nM vinorelbine caused JNK kinase phosphorylation in 30 min but 10 µ&Mgr; of the JNK inhibitor ii did not block the increase on HES1 and HEY1 mRNA after 12 h treatment when the maximum increase of HES1 and HEY1 occurs. ConclusionsVinorelbine can activate target genes of Notch without direct action on NICD expression. This effect cannot be attributed to the already known pathways that regulate Notch, NF-kB and c-JUN. There was however a striking effect of NF-kB inhibition on Dll4 expression. Crosstalk with other pathways deserves further investigation. Vinorelbine can activate target genes of Notch without direct action on NICD expression. This effect cannot be attributed to the already known pathways that regulate Notch, NF-kB and c-JUN. There was however a striking effect of NF-kB inhibition on Dll4 expression. Crosstalk with other pathways deserves further investigation.