Nanoparticle encapsulation of non-genotoxic p53 activator Inauhzin-C for improved therapeutic efficacy.
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ABSTRACT:
SUBMITTER: Bhattarai N
PROVIDER: S-EPMC8171090 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Photodynamic therapy regimens, which use light-activated molecules known as photosensitizers, are highly selective against many malignancies and can bypass certain challenging therapeutic resistance mechanisms. Photosensitizers such as the small cationic molecule EtNBS (5-ethylamino-9-diethyl-aminobenzo[a]phenothiazinium chloride) have proven potent against cancer cells that reside within acidic and hypoxic tumour microenvironments. At higher doses, however, these photosensitizers induce "dark toxicity" through light-independent mechanisms. In this study, we evaluated the use of nanoparticle encapsulation to overcome this limitation. Interestingly, encapsulation of the compound within poly(lactic-co-glycolic acid) (PLGA) nanoparticles (PLGA-EtNBS) was found to significantly reduce EtNBS dark toxicity while completely retaining the molecule's cytotoxicity in both normoxic and hypoxic conditions. This dual effect can be attributed to the mechanism of release: EtNBS remains encapsulated until external light irradiation, which stimulates an oxygen-independent, radical-mediated process that degrades the PLGA nanoparticles and releases the molecule. As these PLGA-encapsulated EtNBS nanoparticles are capable of penetrating deeply into the hypoxic and acidic cores of 3D spheroid cultures, they may enable the safe and efficacious treatment of otherwise unresponsive tumour regions.
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Project description:BackgroundPreviously, we reported that Inauhzin (INZ) induces p53 activity and suppresses tumor growth by inhibiting Sirt1. However, it remains unknown whether INZ may globally affect p53-dependent gene expression or not. Herein, we have conducted microarray and real-time PCR analyses of gene expression to determine the global effect of INZ on human p53-responsive transcriptome.Methodology/principal findingsIn this study, we conducted microarray analysis followed by PCR validation of general gene expression in HCT116(p53+/+) and HCT116(p53-/-) cells treated with or without INZ. Microarray data showed that 324 genes were up-regulated by ≥ 2.3-fold and 266 genes were down-regulated by ≥ 2-fold in response to INZ treatment in a p53-dependent manner. GO analysis for these genes further revealed that INZ affects several biological processes, including apoptosis (GO:0006915), cell cycle (GO:0007049), immune system process (GO:0002376), and cell adhesion (GO:0007155), which are in line with p53 functions in cells. Also, pathway and STRING analyses of these genes indicated that the p53-signaling pathway is the most significant pathway responsive to INZ treatment as predicted, since a number of these p53 target genes have been previously reported and some of them were validated by RT-qPCR. Finally, among the 9 tested and highly expressed genes, ACBD4, APOBEC3C, and FLJ14327 could be novel p53 target genes, for they were up-regulated by INZ in HCT116(p53+/+) cells, but not in HCT116(p53-/-) cells.Conclusions/significanceFrom our whole genome microarray analysis followed by validation with RT-qPCR, we found that INZ can indeed induce the expression of p53 target genes at a larger scale or globally. Our findings not only verify that INZ indeed activates the p53 signaling pathway, but also provide useful information for identifying novel INZ and/or p53 targets. The global effect of INZ on human p53-responsive transcriptome could also be instrumental to the future design of INZ clinical trials.
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Project description:Several proteins have been suggested in promoting tumor formation in numerous human tissues by inactivating the tumor suppressor p53. This has generated interest in the development of small molecules to block these inhibitors of p53 and to regain p53 activity. Recently, we identified a small molecule, Inauhzin, which can inhibit SIRT1 activity and activate p53. SIRT1 is a deacetylase that deacetylates p53 and facilitates Mdm2 mediated p53 destabilization. In this study, we tested if combining Inauhzin with Nutlin-3, an inhibitor of MDM2-p53 binding, might synergistically activate p53 to suppress tumor growth. Indeed, at lower doses, combination of Inauhzin and Nutlin-3 exhibited a synergistic effect on inhibiting cell growth and promoting apoptosis in human colon and lung cancer cell lines in a p53-dependent fashion. Minimal effects were observed with treatment of either compound alone. Using a xenograft tumor model, we also showed a synergistic effect with both compounds. Thus, to fully regain p53 activity, targeting its multiple inhibitory proteins might be a better approach. Our study provides evidence supporting this concept for achieving better therapeutic efficacy in tumors that possess wild type p53.
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Project description:Toxicity and chemoresistance are two major issues to hamper the success of current standard tumor chemotherapy. Combined therapy of agents with different mechanisms of action is a feasible and effective means to minimize the side effects and avoid the resistance to chemotherapeutic drugs while improving the antitumor effects. As the most essential tumor suppressor, p53 or its pathway has been an attractive target to develop a new type of molecule-targeting anticancer therapy. Recently, we identified a small molecule, Inauhzin (INZ), which can specifically activate p53 by inducing its deacetylation. In this study, we tested if combination with INZ could sensitize tumor cells to the current chemotherapeutic drugs, cisplatin (CIS) and doxorubicin (DOX). We found that compared with any single treatment, combination of lower doses of INZ and CIS or DOX significantly promoted apoptosis and cell growth inhibition in human non-small lung cancer and colon cancer cell lines in a p53-dependent fashion. This cooperative effect between INZ and CIS on tumor suppression was also confirmed in a xenograft tumor model. Therefore, this study suggests that specifically targeting the p53 pathway could enhance the sensitivity of cancer cells to chemotherapeutic agents and markedly reduce the doses of the chemotherapy, possibly decreasing its adverse side effects.
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