title: The MDM2 small-molecule inhibitor RG7388 leads to potent tumor inhibition in p53 wild-type neuroblastoma.
abstract: Neuroblastoma is an aggressive pediatric malignancy which is >98% p53 wild-type at diagnosis. As a primary repressor of p53 activity and part of a p53-activated negative feedback loop, targeting of mouse double minute 2 homolog (MDM2) is an attractive therapeutic approach to reactivation of p53. Since development of the first selective MDM2 inhibitor, Nutlin-3a, newer compounds have been developed for increased potency and improved bioavailability. Herein, we sought to determine the efficacy and specificity of a second-generation MDM2 inhibitor, RG7388, in neuroblastoma cell lines and xenografts and examine its effect on the p53-independent pathway of hypoxia-inducible factor-1 alpha (HIF-1α)/vascular endothelial growth factor (VEGF). Cell viability and apoptosis studies were performed on the neuroblastoma cell lines, NGP, SH-SY5Y, LAN-5, LAN-5 si-p53 (p53 silenced), and SK-N-AS (p53 null). RG7388 potently decreased cell proliferation and activated p53-dependent apoptosis. Tumor-bearing mice treated with RG7388 demonstrated significant tumor inhibition by 59% in NGP (P= 0.003), 67% in SH-SY5Y (P= 0.006), and 75% in LAN-5 (P= 0.0019) p53 wild-type xenograft tumors, but no inhibitory effect on LAN-5 si-p53 or SK-N-AS p53-silenced/null xenograft tumors. Moreover, RG7388 was found to inhibit the p53-independent pathway of HIF-1α/VEGF with decreased gene expression and alteration of angiogenesis. Our study supports the further evaluation of RG7388 as a novel treatment option in p53 wild-type neuroblastoma at diagnosis and relapse.
authors.affiliation: Division of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: A
authors.initials: A
authors.lastname: Lakoma
authors.affiliation: Department of Pediatrics, Section of Hematology-Oncology, Texas Children's Cancer Center, Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: E
authors.initials: E
authors.lastname: Barbieri
authors.affiliation: Department of Pediatrics, Section of Hematology-Oncology, Texas Children's Cancer Center, Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: S
authors.initials: S
authors.lastname: Agarwal
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA.
authors.forename: J
authors.initials: J
authors.lastname: Jackson
authors.affiliation: Department of Pediatrics, Section of Hematology-Oncology, Texas Children's Cancer Center, Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Division of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: M
authors.initials: M
authors.lastname: McVay
authors.affiliation: Department of Pediatrics, Section of Hematology-Oncology, Texas Children's Cancer Center, Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Shohet
authors.affiliation: Division of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA; Division of Pediatric Surgery, Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA.
authors.forename: E S
authors.initials: ES
authors.lastname: Kim