The Hdm2 (Mdm2) Inhibitor Nvp-Cgm097 Inhibits Tumor Cell Proliferation And Shows Additive Effects With 5-Fluorouracil On The P53-P21-Rb-E2f1 Cascade In The P53(Wild Type) Neuroendocrine Tumor Cell Line Got1

Background/Aims: The tumor suppressor p53 is depleted in many tumor cells by the E3 ubiquitin ligase mouse double minute 2 homolog (MDM2) through MDM2/p53 interaction. A novel target for inhibiting p53 degradation and for causing reexpression of p53(wild type) is inhibition of MDM2. The small molecule NVP-CGM097 is a novel MDM2 inhibitor. We investigated MDM2 inhibition as a target in neuroendocrine tumor cells in vitro. Methods: Human neuroendocrine tumor cell lines from the pancreas (BON1), lung (NCI-H727), and midgut (GOT1) were incubated with the MDM2 inhibitor NVP-CGM097 (Novartis) at concentrations from 4 to 2,500 nM. Results: While p53 (wild type) GOT1 cells were sensitive to NVP-CGM097, p53(mutated) BON1 and p53(mutated) NCI-H727 cells were resistant to NVP-CGM097. Incubation of GOT1 cells with NVP-CGM097 at 100, 500, and 2,500 nM for 96 h caused a significant decline in cell viability to 84.9 +/- 9.2% (p < 0.05), 77.4 +/- 6.6% (p < 0.01), and 47.7 +/- 9.2% (p < 0.01). In a Western blot analysis of GOT1 cells, NVP-CGM097 caused a dose-dependent increase in the expression of p53 and p21 tumor suppressor proteins and a decrease in phospho-Rb and E2F1. Experiments of co-incubation of NVP-CGM097 with 5-fluorouracil, temozolomide, or everolimus each showed additive antiproliferative effects in GOT1 cells. NVP-CGM097 and 5-fluorouracil increased p53 and p21 expression in an additive manner. Conclusions: MDM2 inhibition seems a promising novel therapeutic target in neuroendocrine tumors harboring p53(wild type). Further investigations should examine the potential role of MDM2 inhibitors in neuroendocrine tumor treatment. (C) 2016 S. Karger AG, Basel