Objective:

To explore the potential function of MDM2-mediated Notch/hes1 signaling pathway in cisplatin-induced renal injury.

Methods:

The acute renal injury models of mice after intraperitoneal injection of cisplatin in vivo, and the apoptotic models of human renal tubular epithelial (HK-2) cells induced by cisplatin in vitro, were conducted respectively. The renal function-related parameters were measured. The renal tissue pathological changes and apoptosis were observed by PAS staining and TUNEL staining, respectively. Cell viability and apoptosis were detected by MTT and flow cytometry. Notch/hes1 pathway-related proteins were tested by Western blotting.

Results:

After mice injected by cisplatin, the levels of Cr, BUN, urine cystatin C, urine NGAL and urine ACR were increased and GFR was decreased with the elevation of renal tubular injury scores, the upregulation of the expressions of MDM2, N1ICD, Hes1 and Cleaved caspase-3, as well as the enhancement of cell apoptosis accompanying decreased ratio of Bcl-2/Bax. However, these cisplatin-induced renal injuries of mice have been improved by MDM2 inhibition. Besides, the declined viability, increased cytotoxicity, and enhanced apoptosis were observed in cisplatin-induced HK-2 cells, with the activated Notch/hes1 pathway. Notably, the phenomenon was alleviated in cisplatin-induced HK-2 cells transfected with MDM2 shRNA, but was severer in those co-treated with AdMDM2. Moreover, Notch1 siRNA can reverse the injury of AdMDM2 on HK-2 cells.

Conclusion:

Inhibiting MDM2 could reduce cell apoptosis through blocking Notch/hes1 signaling pathway, thus alleviating the acute renal injury caused by cisplatin.

中文翻译：

---

MDM2 抑制通过 Notch/hes1 信号通路失活改善顺铂诱导的小鼠肾损伤。

客观的：

探讨MDM2介导的Notch/hes1信号通路在顺铂致肾损伤中的潜在作用。

方法：

分别建立小鼠体内顺铂腹腔注射后急性肾损伤模型和体外顺铂诱导人肾小管上皮（HK-2）细胞凋亡模型。测量肾功能相关参数。PAS染色和TUNEL染色分别观察肾组织病理变化和细胞凋亡。通过MTT和流式细胞术检测细胞活力和凋亡。通过Western印迹检测Notch/hes1通路相关蛋白。

结果：

小鼠注射顺铂后，随着肾小管损伤评分的升高、MDM2、N1ICD、Hes1和Cleaved的表达上调，Cr、BUN、尿胱抑素C、尿NGAL和尿ACR水平升高，GFR降低caspase-3，以及伴随 Bcl-2/Bax 比率降低的细胞凋亡增强。然而，这些顺铂诱导的小鼠肾损伤已通过 MDM2 抑制得到改善。此外，在顺铂诱导的 HK-2 细胞中观察到活力下降、细胞毒性增加和细胞凋亡增强，同时 Notch/hes1 通路被激活。值得注意的是，这种现象在用 MDM2 shRNA 转染的顺铂诱导的 HK-2 细胞中得到缓解，但在用 AdMDM2 共同处理的细胞中更为严重。此外，Notch1 siRNA 可以逆转 AdMDM2 对 HK-2 细胞的损伤。

结论：

抑制MDM2可通过阻断Notch/hes1信号通路减少细胞凋亡，从而减轻顺铂引起的急性肾损伤。