The Selectivity for Tumor Cells of Nuclear-Directed Cytotoxic RNases Is Mediated by the Nuclear/Cytoplasmic Distribution of p27KIP1.

Glòria García-Galindo,Jessica Castro,Marlon Bravo,Jesús Matés,Antoni Benito,Marc Ribó,Maria Vilanova

doi:10.3390/molecules26051319

Glòria García-Galindo, Jessica Castro + Show 5 more

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https://doi.org/10.3390/molecules26051319

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Abstract

Although single targeted anti-cancer drugs are envisaged as safer treatments because they do not affect normal cells, cancer is a very complex disease to be eradicated with a single targeted drug. Alternatively, multi-targeted drugs may be more effective and the tumor cells may be less prone to develop drug resistance although these drugs may be less specific for cancer cells. We have previously developed a new strategy to endow human pancreatic ribonuclease with antitumor action by introducing in its sequence a non-classical nuclear localization signal. These engineered proteins cleave multiple species of nuclear RNA promoting apoptosis of tumor cells. Interestingly, these enzymes, on ovarian cancer cells, affect the expression of multiple genes implicated in metabolic and signaling pathways that are critic for the development of cancer. Since most of these targeted pathways are not highly relevant for non-proliferating cells, we envisioned the possibility that nuclear directed-ribonucleases were specific for tumor cells. Here, we show that these enzymes are much more cytotoxic for tumor cells in vitro. Although the mechanism of selectivity of NLSPE5 is not fully understood, herein we show that p27KIP1 displays an important role on the higher resistance of non-tumor cells to these ribonucleases.

Highlights

Members of the pancreatic ribonuclease (RNase) superfamily display an array of biological activities ranging from cytotoxicity to angiogenesis
Onconase, an RNase isolated from Rana pipiens, reached phase II/III of clinical trials for the treatment of malignant mesothelioma but failed due to its renal toxicity when administered at high concentrations
Among the designed variants of HP-RNase some are cytotoxic because they are either resistant to the cytosolic RNase inhibitor (RI) or because they are targeted to tumor cells through specific ligands that ensure an efficient arrival to the cytosol

Summary

Introduction

Members of the pancreatic ribonuclease (RNase) superfamily display an array of biological activities ranging from cytotoxicity to angiogenesis. Cytotoxicity is highly attractive since such enzymes can be used, alone or conjugated to ligands or antibodies, as non-mutagenic therapeutic agents for cancer treatment [1,2,3]. The generation of cytotoxic variants of human pancreatic RNase (HP-RNase), which has lower renal toxicity, is less immunogenic and displays higher ribonucleolytic activity than onconase [4,5,6], is a potentially useful approach to get non-genotoxic antitumor agents. Among the designed variants of HP-RNase some are cytotoxic because they are either resistant to the cytosolic RNase inhibitor (RI) or because they are targeted to tumor cells through specific ligands that ensure an efficient arrival to the cytosol (for a review see [3]). We anticipated an alternative strategy to produce cytotoxic RNases consistent in their engineering to direct them to the nucleus [7,8], which is free of RI [9]

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