Pljesa-Ercegovac Marija, Mimic-Oka Jasmina, Dragicevic Dejan, Savic-Radojevic Ana, Opacic Marija, Pljesa Steva, Radosavljevic Radoslav, Simic Tatjana
Institute of Biochemistry, Faculty of Medicine, University of Belgrade, Belgrade, Serbia.
Urol Oncol. 2008 Mar-Apr;26(2):175-81. doi: 10.1016/j.urolonc.2007.02.007. Epub 2007 Nov 26.
We aimed to discern the role of glutathione (GSH) associated enzymes in maintaining high GSH levels in renal cell carcinoma (RCC) of the clear cell type and analyze RCC enzyme antioxidant capacity. Since changes in cellular redox balance in RCC might also be related to alterations of glutathione S-transferase (GST) phenotype, GST class alpha and pi expression was also explored.
Human kidney specimens of tumor and distant nontumor regions were obtained from 15 patients with RCC at the time of surgery. The activities of GSH-replenishing enzymes, gamma-glutamylcysteine synthetase (gamma-GCS), gamma-glutamyl transferase (gamma-GT), and glutathione reductase (GR), as well as the activities of antioxidant enzymes glutathione peroxidase (GPX) and catalase (CAT) were determined spectrophotometrically. GST alpha and pi class expression was determined by immunoblot.
In the course of renal cancerization, significant changes appear in the activities of GSH-replenishing and antioxidant enzymes. The activity of the key enzyme of GSH synthesis, gamma-GCS, is up-regulated (P < 0.001), while the activities of gamma-GT and GR are down-regulated in renal tumors compared to nontumor tissue (P < 0.001 and P < 0.05, respectively). Activities of GPX and CAT were also down-regulated (P < 0.001 and P < 0.05, respectively) in RCC. Changes in enzyme antioxidant capacity in RCC were associated with decreased GST class alpha (P < 0.001) and unchanged GST pi expression at the protein level.
Changes in redox status in RCC as a consequence of decreased enzyme antioxidant capacity, together with altered GST alpha expression, may be important factors in development and tumor growth. The up-regulation of gamma-GCS and high levels of GSH in RCC may be an attempt to limit injury caused by oxidative stress.
我们旨在探究谷胱甘肽（GSH）相关酶在维持透明细胞型肾细胞癌（RCC）中高GSH水平方面的作用，并分析RCC酶的抗氧化能力。由于RCC细胞氧化还原平衡的变化可能也与谷胱甘肽S-转移酶（GST）表型的改变有关，因此还对GSTα和π类的表达进行了研究。
在手术时从15例RCC患者获取肿瘤及远处非肿瘤区域的人肾标本。用分光光度法测定GSH补充酶γ-谷氨酰半胱氨酸合成酶（γ-GCS）、γ-谷氨酰转移酶（γ-GT）和谷胱甘肽还原酶（GR）的活性，以及抗氧化酶谷胱甘肽过氧化物酶（GPX）和过氧化氢酶（CAT）的活性。通过免疫印迹法测定GSTα和π类的表达。
在肾癌发生过程中，GSH补充酶和抗氧化酶的活性出现显著变化。与非肿瘤组织相比，肾肿瘤中GSH合成的关键酶γ-GCS的活性上调（P<0.0），而γ-GT和GR的活性下调（分别为P<0.0和P<0.05）。RCC中GPX和CAT的活性也下调（分别为P<0.0和P<0.05）。RCC中酶抗氧化能力的变化与GSTα类的降低（P<0.0）以及蛋白质水平上GSTπ表达未改变有关。
由于酶抗氧化能力降低导致的RCC氧化还原状态变化，以及GSTα表达改变，可能是肿瘤发生和生长的重要因素。RCC中γ-GCS的上调和高GSH水平可能是限制氧化应激所致损伤的一种尝试。
