Mechanisms of translation inhibition and suppression of Stress Granule formation by cisplatin

ABSTRACT Platinum-based antineoplastic drugs, such as cisplatin, are commonly used to induce tumor cell death. Cisplatin is believed to induce apoptosis as a result of cisplatin-DNA adducts that inhibit DNA and RNA synthesis. Although idea that DNA damage underlines anti-proliferative effects of cisplatin is dominant in cancer research, there is a poor correlation between the degree of the cell sensitivity to cisplatin and the extent of DNA platination. Here, we propose a novel mechanism of cisplatin-mediated cytotoxicity. We show that cisplatin suppresses formation of Stress Granules (SGs), pro-survival RNA granules with multiple roles in cellular metabolism. Mechanistically, cisplatin inhibits cellular translation to promote disassembly of polysomes and aggregation of ribosomal subunits. As SGs are in equilibrium with polysomes, cisplatin-induced shift towards ribosomal aggregation suppresses SG formation and promotes cellular death. Our data also explain nephrotoxic, neurotoxic and ototoxic effects of cisplatin treatment.