Tuberin regulates reactive oxygen species in renal proximal cells, kidney from rodents, and kidney from patients with tuberous sclerosis complex

• Published in: Cancer science Vol. 107; no. 8; pp. 1092 - 1100
• Main Authors: Habib, Samy L., Abboud, Hanna E.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.08.2016; John Wiley and Sons Inc
• Subjects: Animals; Binding sites; Bisindolylmaleimide I; Cancer; Cell culture; Cell growth; Cells, Cultured; CYBB protein; Deoxyribonucleic acid; DNA; DNA damage; Embryo fibroblasts; Embryo, Mammalian - cytology; Embryos; Enzymes; Fibroblasts; Fibroblasts - cytology; Fibroblasts - metabolism; Gene expression; Humans; Isoforms; Kidney; Kidney Cortex - enzymology; Kidney Cortex - metabolism; Kidney Tubules, Proximal - cytology; Kidney Tubules, Proximal - metabolism; Kinases; Male; Mice; Mutation; NAD(P)H oxidase; NADPH Oxidase 1; NADPH Oxidases - genetics; NADPH Oxidases - metabolism; Nox protein; NOX4 protein; Original; Oxidative stress; Prostate; Protein expression; Protein kinase C; Proteins; Rapamycin; Rats; Reactive oxygen species; Reactive Oxygen Species - metabolism; renal cells; Renal cortex; RNA, Messenger - genetics; RNA, Messenger - metabolism; Studies; TOR Serine-Threonine Kinases - antagonists & inhibitors; TOR Serine-Threonine Kinases - metabolism; Tuberous sclerosis; Tuberous Sclerosis - metabolism; Tuberous Sclerosis Complex 2; Tuberous Sclerosis Complex 2 Protein; tumor suppressor gene; Tumor Suppressor Proteins - deficiency; Tumor Suppressor Proteins - metabolism; tumorigenesis; United States > US; tumorigenesis; Kidney; renal cells; tumor suppressor gene; reactive oxygen species
• ISSN: 1347-9032; 1349-7006; 1349-7006
• DOI: 10.1111/cas.12984

Reactive oxygen species (ROS) are an important endogenous source of DNA damage and oxidative stress in all cell types. Deficiency in tuberin resulted in increased oxidative DNA damage in renal cells. In this study, the role of tuberin in the regulating of ROS and NADPH oxidases was investigated. Formation of ROS and activity of NADPH oxidases were significantly higher in mouse embryonic fibroblasts and in primary culture of rat renal proximal tubular epithelial tuberin‐deficient cells compared to wild‐type cells. In addition, expression of NADPH oxidase (Nox)1, Nox2, and Nox4 (Nox isoforms) was higher in mouse embryonic fibroblasts and renal proximal tubular epithelial tuberin‐deficient cells compared to wild‐type cells. Furthermore, activity levels of NADPH oxidases and protein expression of all Nox isoforms were higher in the renal cortex of rat deficient in tuberin. However, treatment of tuberin‐deficient cells with rapamycin showed significant decrease in protein expression of all Nox. Significant increase in protein kinase C βII expression was detected in tuberin‐deficient cells, whereas inhibition of protein kinase C βII by bisindolylmaleimide I resulted in decreased protein expression of all Nox isoforms. In addition, treatment of mice deficient in tuberin with rapamycin resulted in significant decrease in all Nox protein expression. Moreover, protein and mRNA expression of all Nox were highly expressed in tumor kidney tissue of patients with tuberous sclerosis complex compared to control kidney tissue of normal subjects. These data provide the first evidence that tuberin plays a novel role in regulating ROS generation, NADPH oxidase activity, and Nox expression that may potentially be involved in development of kidney tumor in patients with tuberous sclerosis complex. Our data comprise the first report to provide a novel role of tuberin in regulating ROS generation and Noxs expression. The data showed a novel mechanism by which tuberin/PKC/mTOR pathway regulates ROS and Noxs protein in several cell lines, animal models as well as human kidney tumor from TSC patients. These data showed a novel molecular mechanism by which tuberin regulates Nox‐derived ROS in kidney tumorigenesis.