Ahn Y S, Zerban H, Grobholz R, Bannasch P
Abteilung für Cytopathologie, Deutsches Krebsforschungszentrum, Heidelberg, Germany.
Carcinogenesis. 1992 Dec;13(12):2329-34. doi: 10.1093/carcin/13.12.2329.
Renal clear cell tubules and clear/acidophilic cell tumors were induced in male Sprague-Dawley rats by 7 weeks oral administration (stop model) of N-nitrosomorpholine (NNM) at a concentration of 12 mg/100 ml in the drinking water. Twelve, 23 and 34 weeks after withdrawal of NNM serial cryostat sections of the kidneys were histochemically analyzed for the following parameters: glucose transporter proteins (GLUT1, GLUT2), glycogen content and the activities of glycogen synthase (SYN), glycogen phosphorylase (PHO), glucose-6-phosphatase (G6Pase), glucose-6-phosphate dehydrogenase (G6PDH), hexokinase (HK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PK), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), alkaline phosphatase (ALP), acid phosphatase (ACP) and gamma-glutamyltransferase (GGT). Clear cell (glycogenotic) tubules first appeared at 23 weeks, and clear/acidophilic cell tumors at 34 weeks after withdrawal of the carcinogen. G6Pase, ALP, GGT and GLUT2 were absent in clear cell tubules, clear/acidophilic cell tubules, and clear/acidophilic cell tumors indicating a sequential origin of all these types of lesions from the collecting duct system, in line with previous morphological findings. In comparison to the collecting duct epithelium, glycogenotic tubules demonstrated an increased activity of PHO and reduced activities of glycolytic and mitochondrial enzymes, which were accompanied by a strongly reduced expression of GLUT1. Moderately increased activities of glycolytic and mitochondrial enzymes were observed in the clear cells of clear/acidophilic cell tubules and tumors compared with those in glycogenotic tubules. They had slightly increased activities of the glycolytic enzymes GAPDH and PK compared with normal collecting duct epithelium, while most of them were nearly lacking in GLUT1. Our findings suggest that glycogen storage is not due to an increased uptake of glucose from the blood, but results from a disturbance in intracellular flux of metabolites. The development of clear cell tubules from the normal collecting duct epithelium is accompanied by a markedly decreased expression of GLUT1 along with a reduction in glycolytic and mitochondrial enzymes. This reduction of enzyme activities is replaced by an increase in enzyme activities in clear/acidophilic cell tumors indicating a fundamental shift in carbohydrate metabolism during progression from preneoplastic to neoplastic lesions.
通过在饮用水中以12毫克/100毫升的浓度口服给予雄性Sprague-Dawley大鼠7周的N-亚硝基吗啉（NNM）来诱导肾透明细胞小管和透明/嗜酸性细胞瘤（停药模型）。在停用NNM后的12周、23周和34周，对肾脏的系列冰冻切片进行组织化学分析，检测以下参数：葡萄糖转运蛋白（GLUT1、GLUT2）、糖原含量以及糖原合酶（SYN）、糖原磷酸化酶（PHO）、葡萄糖-6-磷酸酶（G6Pase）、葡萄糖-6-磷酸脱氢酶（G6PDH）、己糖激酶（HK）、甘油醛-3-磷酸脱氢酶（GAPDH）、丙酮酸激酶（PK）、琥珀酸脱氢酶（SDH）、苹果酸脱氢酶（MDH）、碱性磷酸酶（ALP）、酸性磷酸酶（ACP）和γ-谷氨酰转移酶（GGT）的活性。透明细胞（糖原性）小管在停药后23周首次出现，透明/嗜酸性细胞瘤在停药后34周出现。在透明细胞小管、透明/嗜酸性细胞小管和透明/嗜酸性细胞瘤中均未检测到G6Pase、ALP、GGT和GLUT2，这表明所有这些类型的病变均起源于集合管系统，与先前的形态学研究结果一致。与集合管上皮相比，糖原性小管中PHO活性增加，糖酵解和线粒体酶活性降低，同时GLUT1表达显著降低。与糖原性小管相比，在透明/嗜酸性细胞小管和肿瘤的透明细胞中观察到糖酵解和线粒体酶活性适度增加。与正常集合管上皮相比，它们的糖酵解酶GAPDH和PK活性略有增加，而大多数几乎缺乏GLUT1。我们的研究结果表明，糖原储存并非由于从血液中摄取葡萄糖增加，而是由于细胞内代谢物通量紊乱所致。从正常集合管上皮发展而来的透明细胞小管伴随着GLUT1表达的显著降低以及糖酵解和线粒体酶的减少。酶活性的这种降低在透明/嗜酸性细胞瘤中被酶活性的增加所取代，这表明从癌前病变发展为肿瘤病变过程中碳水化合物代谢发生了根本性转变。
