Inhibition of PKCδ reduces cisplatin-induced nephrotoxicity without blocking chemotherapeutic efficacy in mouse models of cancer
Navjotsingh Pabla, Guie Dong, Man Jiang, Shuang Huang, M. Vijay Kumar, Robert O. Messing, Zheng Dong
Navjotsingh Pabla, Guie Dong, Man Jiang, Shuang Huang, M. Vijay Kumar, Robert O. Messing, Zheng Dong
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Research Article Nephrology

Inhibition of PKCδ reduces cisplatin-induced nephrotoxicity without blocking chemotherapeutic efficacy in mouse models of cancer

Abstract

Cisplatin is a widely used cancer therapy drug that unfortunately has major side effects in normal tissues, notably nephrotoxicity in kidneys. Despite intensive research, the mechanism of cisplatin-induced nephrotoxicity remains unclear, and renoprotective approaches during cisplatin-based chemotherapy are lacking. Here we have identified PKCδ as a critical regulator of cisplatin nephrotoxicity, which can be effectively targeted for renoprotection during chemotherapy. We showed that early during cisplatin nephrotoxicity, Src interacted with, phosphorylated, and activated PKCδ in mouse kidney lysates. After activation, PKCδ regulated MAPKs, but not p53, to induce renal cell apoptosis. Thus, inhibition of PKCδ pharmacologically or genetically attenuated kidney cell apoptosis and tissue damage, preserving renal function during cisplatin treatment. Conversely, inhibition of PKCδ enhanced cisplatin-induced cell death in multiple cancer cell lines and, remarkably, enhanced the chemotherapeutic effects of cisplatin in several xenograft and syngeneic mouse tumor models while protecting kidneys from nephrotoxicity. Together these results demonstrate a role of PKCδ in cisplatin nephrotoxicity and support targeting PKCδ as an effective strategy for renoprotection during cisplatin-based cancer therapy.

Authors

Navjotsingh Pabla, Guie Dong, Man Jiang, Shuang Huang, M. Vijay Kumar, Robert O. Messing, Zheng Dong

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Figure 3

Effects of PKCδ inhibition on cisplatin-induced apoptosis in RPTCs.

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Effects of PKCδ inhibition on cisplatin-induced apoptosis in RPTCs. (A–C...
(A–C) RPTCs were treated with 20 μM cisplatin for 16 hours in the absence or presence of 10 μM rottlerin, BisI, or Go6976. (A) Morphology. After treatment, cells were stained with Hoechst33342. Cellular and nuclear morphology was recorded by phase-contrast and fluorescence microscopy. Original magnification, ×400. (B) Flow cytometric analysis of apoptosis. After treatment, cells were stained with Annexin V–FITC and PI for flow cytometry. Values in the plots represent percentages of Annexin V–FITC–positive cells. (C) Inhibition of Bax translocation and cytochrome c (cyt c) release during cisplatin treatment by rottlerin. Cells were fractionated into cytosolic (cyto) and membrane-bound organellar fractions for immunoblot analysis of Bax and cytochrome c. Mito, mitochondria. (D) Inhibition of cisplatin-induced apoptosis by dominant-negative PKCδ. RPTCs were cotransfected with pEGFP-C3 and a PKC plasmid (PKCδ-KD, PKCδ-CF, or PKCα-KD), and then treated with 20 μM cisplatin for 16 hours. Transfected cells (expressing GFP) were examined for the percentage of apoptosis by morphological criteria. Mean ± SD, n = 4. *P < 0.05 versus untreated control cells, #P < 0.05 versus cisplatin-treated GFP/empty vector–transfected cells.