Critical subcellular targets of cisplatin and related platinum analogs in rat renal proximal tubule cells

Abstract

The clinical usefulness of chemotherapeutic agents containing the platinum moiety is often limited by their nephrotoxicity. To investigate the mechanism of nephrotoxicity, and to assess the effects of platinum analogs on specific organelles and basal protein synthesis, biochemical and ultrastructural analyses were performed in rat renal proximal tubule cells (RPTCs). Neutral red (NR) uptake was used to measure lysosomal function, and conversion of MTT to formazan used to assess mitochondrial function. Despite their differential toxicity, cisplatin, carboplatin and CI-973 caused similar progressive inhibition of specific functions, suggesting they may share a common mechanism of nephrotoxicity. Protein synthesis was the earliest indicator of toxicity, followed by NR uptake and MTT conversion. Fluorescent probes for lysosomes (acridine orange) and mitochondria (rhodamine 123) confirmed that cisplatin's toxicity to RPTCs was delayed and cumulative. Condensation of nucleolar components and fragmentation of RER were observed in RPTCs treated for as little as two hours. Since the nucleolus is the site of ribosome biogenesis, the early inhibition of protein synthesis by cisplatin may arise from disruption of this region. In contrast, mitochondrial dysfunction and swelling were late-stage events, and are therefore unlikely to be the primary targets of nephrotoxic platinum compounds.

Dependence of Cisplatin-Induced Cell Death In Vitro and In Vivo on Cyclin-Dependent Kinase 2

“…It is likely that its anticancer activity depends on formation of DNA intrastrand cross-links (4). Several distinct mechanisms have been proposed for cisplatin cytotoxicity in renal tubule cells, including direct DNA damage (5), caspase activation (6), mitochondrial dysfunction (7), formation of reactive oxygen species (8), effects on the endoplasmic reticulum (9), and activation of TNF-␣ apoptotic pathways (10). However, it is unclear whether cisplatin nephrotoxicity depends on any of these pathways or these apoptotic cascades merely amplify more proximal initiated cell death signals.…”

A Pathophysiologic Role for T Lymphocytes in Murine Acute Cisplatin Nephrotoxicity

“…Approximately 25 to 30% of patients developed renal dysfunction after receiving a single dose of cisplatin (2). The pathogenesis of cisplatin toxicity is attributed to the formation of reactive oxygen species (3), caspase activation (4), DNA damage (5,6), and mitochondrial damage (7). Apoptosis, necrosis, and inflammation have also been recognized as important mechanisms of cisplatin nephrotoxicity in vivo and in vitro (8,9).…”

Protein Kinase C-α and ERK1/2 Mediate Mitochondrial Dysfunction, Decreases in Active Na+ Transport, and Cisplatin-induced Apoptosis in Renal Cells

“…Renal proximal tubular cells (RPTC) 1 are the major target for cisplatin toxicity within the kidney, as cisplatin nephrotoxicity manifests primarily as proximal tubule dysfunction (6 -8). Cisplatin alters a variety of RPTC functions including DNA, mRNA, protein syntheses, transport of organic and inorganic solutes, activities of some ATPases, ␥-glutamyl transpeptidase, and organization of intracellular cytoskeleton (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12).…”