The effectiveness of cisplatin, a mainstay in treatment of many solid organ cancers, is hindered by dose-limiting nephrotoxicity. Cisplatin causes acute kidney injury (AKI) in 30% of patients. Patients who do not develop AKI by clinical standards during the course of treatment are still at risk for long-term decline in kidney function and the development of chronic kidney disease (CKD). The connection between AKI and CKD has become increasingly studied, with renal fibrosis being a hallmark of CKD development. To prevent both the short- and long-term effects of cisplatin, researchers must use models that reflect both types of pathology. Although a lot is known about cisplatin-induced AKI, very little is known about the mechanisms by which repeated low levels of cisplatin lead to fibrosis development. In this review, strategies used in various rodent models to prevent kidney injury, its progression to fibrosis, or both are examined to gain mechanistic insights and identify potential therapeutic targets for cisplatin-induced kidney pathologies. Reviewing the results from these models highlights the diverse and highly complex role of cell death, cell senescence, endoplasmic reticulum stress, autophagy, and immune cell activation in acute and chronic kidney injuries. Use of several models of kidney injury is needed for development of agents that will prevent all aspects of cisplatin-induced kidney injury.

C57BL/6 mice are one of the most commonly used mouse strains in research, especially in kidney injury studies. However, C57BL/6 mice are resistant to chronic kidney disease-associated pathologies, particularly the development of glomerulosclerosis and interstitial fibrosis. Our lab and others developed a more clinically relevant dosing regimen of cisplatin (7 mg/kg cisplatin once a week for four weeks, mice euthanized at Day 24) that leads to the development of progressive kidney fibrosis in FVB/n mice. However, we found that treating C57BL/6 mice with this same dosing regimen does not result in kidney fibrosis. In this study, we demonstrate that increasing the dose of cisplatin to 9 mg/kg once a week for four weeks is sufficient to consistently induce fibrosis in C57BL/6 mice while maintaining animal survival. In addition, we present that cohorts of C57BL/6 mice purchased from Jackson one year apart and mice bred in house display variability in renal outcomes following repeated low dose cisplatin treatment. In depth analyses of this intra-animal variability revealed CCL2 as a marker of cisplatin-induced kidney injury through correlation studies. In addition, significant immune cell infiltration was observed in the kidney after four doses of 9 mg/kg cisplatin, contrary to what has been previously reported. These results indicate that multiple strains of mice can be used with our repeated low dose cisplatin model with dose optimization. Results also indicate that littermate control mice should be used with this model to account for population variability.

Background:Cadmium, an established carcinogen, is a risk factor for prostate cancer. Induction of autophagy is a prerequisite for cadmium-induced transformation and metastasis. The ability of Psoralidin (Pso), a non-toxic, orally bioavailable compound to inhibit cadmium-induced autophagy to prevent prostate cancer was investigated.Methods:Psoralidin was studied using cadmium-transformed prostate epithelial cells (CTPE), which exhibit high proliferative, invasive and colony forming abilities. Gene and protein expression were evaluated by qPCR, western blot, immunohistochemistry and immunofluorescence. Xenograft models were used to study the chemopreventive effects in vivo.Results:Cadmium-transformed prostate epithelial cells were treated with Pso resulting in growth inhibition, without causing toxicity to normal prostate epithelial cells (RWPE-1). Psoralidin-treatment of CTPE cells inhibited the expression of Placenta Specific 8, a lysosomal protein essential for autophagosome and autolysosome fusion, which resulted in growth inhibition. Additionally, Pso treatment caused decreased expression of pro-survival signalling proteins, NFκB and Bcl2, and increased expression of apoptotic genes. In vivo, Pso effectively suppressed CTPE xenografts growth, without any observable toxicity. Tumours from Pso-treated animals showed decreased autophagic morphology, mesenchymal markers expression and increased epithelial protein expression.Conclusions:These results confirm that inhibition of autophagy by Pso plays an important role in the chemoprevention of cadmium-induced prostate carcinogenesis.

Background: Cisplatin-induced kidney injury remains a major obstacle in utilizing cisplatin as a chemotherapeutic for solid-organ cancers. 30% of patients treated with cisplatin develop acute kidney injury (AKI), and even patients who do not develop AKI are at risk for long term declines in kidney function and development of chronic kidney disease (CKD). Modeling cisplatin-induced kidney injury in mice has revealed that repeated, low doses of cisplatin lead to development of kidney fibrosis. This model can be used to examine AKI-to-CKD transition processes. Macrophages play a role in some of these processes, including immune response, wound healing, and tissue remodeling. Depleting macrophage populations in the kidney reduced fibrosis development in other models of renal fibrosis. Methods: We used either C57BL/6 mice with a Ccr2 genetic knockout or liposome encapsulated clodronate (Clodrosome) to deplete macrophage populations during repeated, 9 mg/kg cisplatin treatments. We assessed how immune cell populations were altered in the blood and kidney of these mice and how these alterations impacted development of renal fibrosis and kidney injury. Results: We found that Clodrosome treatment decreased collagen deposition, myofibroblast accumulation, and inflammatory cytokine production, while Ccr2 genetic knockout had no effect on these markers following cisplatin treatment. Additionally, Ccr2-/- mice had decreased levels of F4/80lo infiltrating macrophages in the kidney following cisplatin treatments, but Clodrosome treatment depleted F4/80hi resident and CD206+ M2 macrophages. Conclusions: These data suggest that Clodrosome depletion of F4/80hi and M2 macrophages in the kidney attenuates development of renal fibrosis following repeated, low doses of cisplatin.

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