Research Papers:

Oxidative stress-induced epigenetic changes associated with malignant transformation of human kidney epithelial cells

Prathap Kumar S. Mahalingaiah, Logeswari Ponnusamy and Kamaleshwar P. Singh _

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Oncotarget. 2017; 8:11127-11143. https://doi.org/10.18632/oncotarget.12091

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Prathap Kumar S. Mahalingaiah1, Logeswari Ponnusamy1, Kamaleshwar P. Singh1

1Department of Environmental Toxicology, The Institute of Environmental and Human Health (TIEHH), Texas Tech University, Lubbock, Texas, USA

Correspondence to:

Kamaleshwar P. Singh, email: [email protected]

Keywords: epigenetics, oxidative stress, DNA methylation, kidney cancer, histone modification

Received: June 16, 2016    Accepted: September 05, 2016    Published: September 17, 2016


Renal Cell Carcinoma (RCC) in humans is positively influenced by oxidative stress status in kidneys. We recently reported that adaptive response to low level of chronic oxidative stress induces malignant transformation of immortalized human renal tubular epithelial cells. Epigenetic alterations in human RCC are well documented, but its role in oxidative stress-induced malignant transformation of kidney cells is not known. Therefore, the objective of this study was to evaluate the potential role of epigenetic changes in chronic oxidative stress-induced malignant transformation of HK-2, human renal tubular epithelial cells. The results revealed aberrant expression of epigenetic regulatory genes involved in DNA methylation (DNMT1, DNMT3a and MBD4) and histone modifications (HDAC1, HMT1 and HAT1) in HK-2 cells malignantly transformed by chronic oxidative stress. Additionally, both in vitro soft agar assay and in vivo nude mice study showing decreased tumorigenic potential of malignantly transformed HK-2 cells following treatment with DNA de-methylating agent 5-aza 2’ dC further confirmed the crucial role of DNA hypermethyaltion in oxidative stress-induced malignant transformation. Changes observed in global histone H3 acetylation (H3K9, H3K18, H3K27 and H3K14) and decrease in phospho-H2AX (Ser139) also suggest potential role of histone modifications in increased survival and malignant transformation of HK-2 cells by oxidative stress. In summary, the results of this study suggest that epigenetic reprogramming induced by low levels of oxidative stress act as driver for malignant transformation of kidney epithelial cells. Findings of this study are highly relevant in potential clinical application of epigenetic-based therapeutics for treatments of kidney cancers.

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