Search

Drug resistance induced by increasing intracellular levels of detoxifying agents for conventional platinum(II) drugs such as metallothioneins (MTs) and glutathione (GSH) are the major obstacles for widely used platinum-based chemotherapeutic cancer treatment. Here, we developed trans-geometry platinum (II) drugs with sterically hindered bulky ligands PyPt which is able to hind the GSH attack of platinum drug to overcome cisplatin resistance. Moreover, the PyPt can self-assemble with biodegradable copolymer mPEG-PGA into uniform nanoparticles with PyPt drugs in the polymeric core and PEG as the shell, further protecting PyPt from GSH detoxification to further slow the reaction rate with GSH in vivo. This strategy was developed to bring benefit of not only increasing the solubility of sterically hindered platinum drugs but also combating cisplatin resistance. The M(PyPt) exhibited environment controlled releasing of Pt in tumor micro-environment which prohibited the division of cancer cells. Furthermore, due to the increasing solubility of nanoparticle encapsulated PyPt, the cellular uptake and cytotoxicity of M(PyPt) against both cancer resistance cells was enhanced compared to the cisplatin and PyPt through evaluating with flow cytometry and MTT, respectively. Thus, it was concluded that the M(PyPt) was capable to successfully overcome the cisplatin resistance in the drug-resistant cell line, indicating its potential application in the treatment of clinical cancers with strong cisplatin resistance. Hence the M(PyPt) strategy may represent a promising novel drug delivery system for the local treatment of drug resistance cancer., (Copyright © 2018. Published by Elsevier B.V.)

Background: Isocitrate dehydrogenase wild-type (WT) glioblastoma (GBM) accounts for 90% of all GBMs, yet only 27% of isocitrate dehydrogenase WT-GBMs have p53 mutations. However, the tumor surveillance function of WT-p53 in GBM is subverted by mechanisms that are not fully understood.Methods: We investigated the proteolytic inactivation of WT-p53 by asparaginyl endopeptidase (AEP) and its effects on GBM progression in cancer cells, murine models, and patients' specimens using biochemical and functional assays. The sera of healthy donors (n = 48) and GBM patients (n = 20) were examined by enzyme-linked immunosorbent assay. Furthermore, effects of AEP inhibitors on GBM progression were evaluated in murine models (n = 6-8 per group). The statistical significance between groups was determined using two-tailed Student t tests.Results: We demonstrate that AEP binds to and directly cleaves WT-p53, resulting in the inhibition of WT-p53-mediated tumor suppressor function in both tumor cells and stromal cells via extracellular vesicle communication. High expression of uncleavable p53-N311A-mutant rescue AEP-induced tumorigenesis, proliferation, and anti-apoptotic abilities. Knock down or pharmacological inhibition of AEP reduced tumorigenesis and prolonged survival in murine models. However, overexpression of AEP promoted tumorigenesis and shortened the survival time. Moreover, high AEP levels in GBM tissues were associated with a poor prognosis of GBM patients (n = 83; hazard ratio = 3.94, 95% confidence interval = 1.87 to 8.28; P < .001). A correlation was found between high plasma AEP levels and a larger tumor size in GBM patients (r = 0.6, P = .03), which decreased dramatically after surgery.Conclusions: Our results indicate that AEP promotes GBM progression via inactivation of WT-p53 and may serve as a prognostic and therapeutic target for GBM. [ABSTRACT FROM AUTHOR]