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Kidney Week

Abstract: PO0233

Salubrinal Attenuates Proximal Tubular Cell Injury Induced by Cisplatin

Session Information

  • AKI Mechanisms - 3
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Dong, Guie, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
  • Dong, Zheng, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
Background

Cisplatin is a widely used chemotherapy drug, but it has notorious side effects in kidneys. Effective kidney protective agents are not available for clinical use. Salubrinal is a specific inhibitor of eIF2alpha phosphatase, it promotes eIF2alpha phosphorylation which blocks the formation of the pre-initiation complex and halts global protein translation and protein synthesis. In this study, we examined the effect of salubrinal on cisplatin-induced injury in kidney proximal tubular cells.

Methods

Rat proximal tubular cells (RPTC) were treated with cisplatin or cisplatin with salubrinal for 4, 8, and 24hrs. Cell lysates were collected for immunoblot analysis to examine phospho-eIF2alpha and its related proteins. In addition, other signaling proteins implicated in cisplatin injury were examined, including p53, JNK, p38, and pkcdelta, and ERK. Apoptosis was determined at 24hrs of treatment by phase contrast and fluorescence microscopy following nuclear staining with Hoechst. Caspase activities were measured enzymatically by using DEVD.AFC, a fluorogenic peptide substrate. To examine cell survival, the cells were changed to fresh medium for 48 hrs after 24 hrs of cisplatin treatments with or without Salubrinal.

Results

Salubrinal suppressed apoptosis and caspase activation in RPTC during cisplatin treatment. It also promoted long-term cell survival after cisplatin treatment. In immunoblot analysis, during cisplatin treatment salubrinal increased eIF2alpha phosphorylation. It also increased PERK phosphorylation and the expression of GRP78 and CHOP, indicative of ER stress or unfolded protein response. Signaling pathways including MAP kinases, PKCdelta, and p53 are involved in cisplatin-induced kidney injury. In this regard, Salubrinal decreased JNK and p38 phosphorylation, but increased ERK phosphorylation during cisplatin treatment. Salubrinal diminished phosphorylation of PKCdelta at late time point of cisplatin treatment. However, Salubrinal did not affect p53 expression or its phosphorylation.

Conclusion

Salubrinal has protective effects against cisplatin-induced kidney cell injury. Mechanistically, the protective effects are associated with the increase of UPR and suppression of MAPK signaling but not with p53 activation. The results also suggest that inhibition of global protein synthesis may be a new therapeutic strategy for the side-effects of cisplatin chemotherapy.

Funding

  • NIDDK Support