Lu Qian, Ji Xiao-Jun, Zhou Yue-Xian, Yao Xiao-Qin, Liu Yu-Qing, Zhang Fan, Yin Xiao-Xing
Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, 209 Tongshan Road, Xuzhou 221004, Jiangsu, China.
Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, 209 Tongshan Road, Xuzhou 221004, Jiangsu, China.
Pharmacol Res. 2015 Sep;99:237-47. doi: 10.1016/j.phrs.2015.06.006. Epub 2015 Jul 4.
Quercetin is a classic flavonoid that inhibits the epithelial-mesenchymal transition (EMT) of tumor cells. However, the effects of quercetin on the EMT of renal tubular epithelial cells, a potential mechanism of renal fibrosis and important characteristic of diabetic nephropathy (DN), remain largely unknown. In the present study, we investigated the effects of quercetin on the EMT of two lines of renal tubular proximal epithelial cells (HK-2 and NRK-52E) induced with high glucose and renal fibrosis resulting from type 1 diabetes and tried to clarify the specific mechanisms underlying these effects. The in vitro results showed that the EMT of HK-2 and NRK-52E cells was induced by high glucose, and mTORC1/p70S6K was highly activated in these two cell lines cultured under high glucose. Quercetin effectively ameliorated the high glucose-induced EMT of HK-2 and NRK-52E cells and inhibited the activation of mTORC1/p70S6K. In vivo, diabetic rats showed a significant decline in renal function and severe renal fibrosis at 14 weeks after STZ injection. Furthermore, mTORC1/p70S6K was activated in the renal cortex of diabetic rats. Treatment with quercetin alleviated the decline in renal function, and the progression of renal fibrosis and inhibited mTORC1/p70S6K activation in the diabetic renal cortex. In addition, we examined the protein and mRNA levels of four transcriptional factors (snail, slug, twist and ZEB-1), which regulate E-cadherin expression at the transcriptional level both in vivo and in vitro. The results revealed that the elevated expression of snail and twist in HK-2 and NRK-52E cells cultured under high glucose and in the renal cortex of diabetic rats was inhibited by quercetin. These results demonstrated that quercetin ameliorates the EMT of HK-2 and NRK-52E cells induced by high glucose and renal fibrosis induced by diabetes, and these effects have been associated with the inhibition of the two transcriptional factors (snail and twist) and the activation of mTORC1/p70S6K.
槲皮素是一种经典的黄酮类化合物，可抑制肿瘤细胞的上皮-间质转化（EMT）。然而，槲皮素对肾小管上皮细胞EMT的影响，即肾纤维化的潜在机制和糖尿病肾病（DN）的重要特征，在很大程度上仍不清楚。在本研究中，我们研究了槲皮素对两株高糖诱导的肾小管近端上皮细胞（HK-2和NRK-52E）EMT的影响以及1型糖尿病导致的肾纤维化，并试图阐明这些影响背后的具体机制。体外实验结果表明，高糖诱导了HK-2和NRK-52E细胞的EMT，并且在高糖培养的这两种细胞系中mTORC1/p70S6K被高度激活。槲皮素有效改善了高糖诱导的HK-2和NRK-52E细胞的EMT，并抑制了mTORC1/p70S6K的激活。在体内，链脲佐菌素注射14周后，糖尿病大鼠的肾功能显著下降且出现严重肾纤维化。此外，糖尿病大鼠肾皮质中的mTORC1/p70S6K被激活。槲皮素治疗减轻了肾功能下降和肾纤维化的进展，并抑制了糖尿病肾皮质中mTORC1/p70S6K的激活。此外，我们检测了四种转录因子（Snail、Slug、Twist和ZEB-1）的蛋白质和mRNA水平，它们在体内和体外均在转录水平上调节E-钙黏蛋白的表达。结果显示，槲皮素抑制了高糖培养的HK-2和NRK-52E细胞以及糖尿病大鼠肾皮质中Snail和Twist表达的升高。这些结果表明，槲皮素改善了高糖诱导的HK-2和NRK-52E细胞的EMT以及糖尿病诱导的肾纤维化，并且这些作用与抑制两种转录因子（Snail和Twist）以及mTORC1/p70S6K的激活有关。
