rg7388 and Glioblastoma

Glioblastoma (GBM) is a malignant brain tumor with a poor long-term prognosis due to recurrence from highly resistant GBM cancer stem cells (CSCs), for which the current standard of treatment with temozolomide (TMZ) alone will unlikely produce a viable cure. In addition, CSCs regenerate rapidly and overexpress methyl transferase which overrides the DNA-alkylating mechanism of TMZ, leading to resistance. The objective of this research was to apply the concepts of nanotechnology to develop a multi-drug therapy, TMZ and idasanutlin (RG7388, a potent mouse double minute 2 (MDM2) antagonist), loaded in functionalized nanoparticles (NPs) that target the GBM CSC subpopulation, reduce the cell viability and provide possibility of in vivo preclinical imaging.. Polymer-micellar NPs composed of poly(styrene-b-ethylene oxide) (PS-b-PEO) and poly(lactic-co-glycolic) acid (PLGA) were developed by a double emulsion technique loading TMZ and/or RG7388. The NPs were covalently bound to a 15-nucleotide base-pair CD133 aptamer to target the CD133 antigen expressed on the surfaces of GBM CSCs. For diagnostic functionality, the NPs were labelled with radiotracer Zirconium-89 (. NPs maintained size range less than 100 nm, a low negative charge and exhibited the ability to target and kill the CSC subpopulation when TMZ and RG7388 were used in combination. The targeting function of CD133 aptamer promoted killing in GBM CSCs providing impetus for further development of targeted nanosystems for localized therapy in future in vivo models.. This work has provided a potential clinical application for targeting GBM CSCs with simultaneous diagnostic imaging.

Topics: AC133 Antigen; Animals; Brain Neoplasms; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Delivery Systems; Drug Development; Drug Evaluation, Preclinical; Glioblastoma; Humans; Mice; Micelles; Nanoparticles; Neoplastic Stem Cells; para-Aminobenzoates; Polymers; Proto-Oncogene Proteins c-mdm2; Pyrrolidines; Temozolomide

Resistance is an obstacle of glioma therapy. Despite targeted interventions, tumors harbor primary resistance or become resistant over short course of treatment. This study examined the mouse double minute 2 (MDM2) inhibitor RG7388 together with radiotherapy and analyzed strategies to overcome acquired MDM2 inhibitor resistance in glioblastoma.. Effects of RG7388 and radiotherapy were analyzed in p53 wild-type glioblastoma cell lines and glioma-initiating cells. RG7388 resistant cells were generated by increasing RG7388 doses over 3 months. Regulated pathways were investigated by microarray, qRT-PCR, and immunoblot analysis and specifically inhibited to evaluate rational salvage therapies at RG7388 resistance. Effects of RG7388 and trametinib treatment were challenged in an orthotopical mouse model with RG7388 resistant U87MG glioblastoma cells.. MDM2 inhibition required functional p53 and showed synergistic activity with radiotherapy in first-line treatment. Long-term exposure to RG7388 induced resistance by activation of the extracellular signal-regulated kinases 1/2 (ERK1/2)-insulin growth factor binding protein 1 (IGFBP1) signaling cascade, which was specifically overcome by ERK1/2 pathway inhibition with trametinib and knockdown of IGFBP1. Combining trametinib with continued RG7388 treatment enhanced antitumor effects at RG7388 resistance. These data provide a rationale for combining RG7388 and radiotherapy as first-line therapy with a specific relevance for tumors insensitive to alkylating standard chemotherapy and for the addition of trametinib to continued RG7388 treatment as salvage therapy after acquired resistance against RG7388 for clinical practice.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Drug Resistance, Neoplasm; Glioblastoma; Heterografts; Humans; Insulin-Like Growth Factor Binding Protein 1; Mice; para-Aminobenzoates; Proto-Oncogene Proteins c-mdm2; Pyridones; Pyrimidinones; Pyrrolidines; Signal Transduction; Tumor Suppressor Protein p53