Regulation of pancreatic cancer growth by superoxide

Juan Du, Elke S. Nelson, Andrean L. Simons, Kristen E. Olney, Justin C. Moser, Hannah E. Schrock, Brett A. Wagner, Garry R. Buettner, Brian J. Smith, Melissa L.T. Teoh, Ming Sound Tsao, Joseph J. Cullen

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

K-ras mutations have been identified in up to 95% of pancreatic cancers, implying their critical role in the molecular pathogenesis. Expression of K-ras oncogene in an immortalized human pancreatic ductal epithelial cell line, originally derived from normal pancreas (H6c7), induced the formation of carcinoma in mice. We hypothesized that K-ras oncogene correlates with increased non-mitochondrial-generated superoxide (O2.-), which could be involved in regulating cell growth contributing to tumor progression. In the H6c7 cell line and its derivatives, H6c7er-Kras+ (H6c7 cells expressing K-ras oncogene), and H6c7eR-KrasT (tumorigenic H6c7 cells expressing K-ras oncogene), there was an increase in hydroethidine fluorescence in cell lines that express K-ras. Western blots and activity assays for the antioxidant enzymes that detoxify O2.- were similar in these cell lines suggesting that the increase in hydroethidine fluorescence was not due to decreased antioxidant capacity. To determine a possible non-mitochondrial source of the increased levels of O2.-, Western analysis demonstrated the absence of NADPH oxidase-2 (NOX2) in H6c7 cells but present in the H6c7 cell lines expressing K-ras and other pancreatic cancer cell lines. Inhibition of NOX2 decreased hydroethidine fluorescence and clonogenic survival. Furthermore, in the cell lines with the K-ras oncogene, overexpression of superoxide dismutases that detoxify non-mitochondrial sources of O2.-, and treatment with the small molecule O2.- scavenger Tempol, also decreased hydroethidine fluorescence, inhibited clonogenic survival and inhibited growth of tumor xenografts. Thus, O2.- produced by NOX2 in pancreatic cancer cells with K-ras, may regulate pancreatic cancer cell growth.

Original languageEnglish (US)
Pages (from-to)555-567
Number of pages13
JournalMolecular Carcinogenesis
Volume52
Issue number7
DOIs
StatePublished - Jul 2013

Keywords

  • Oncogene
  • Pancreatic cancer
  • Superoxide

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research

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    Du, J., Nelson, E. S., Simons, A. L., Olney, K. E., Moser, J. C., Schrock, H. E., Wagner, B. A., Buettner, G. R., Smith, B. J., Teoh, M. L. T., Tsao, M. S., & Cullen, J. J. (2013). Regulation of pancreatic cancer growth by superoxide. Molecular Carcinogenesis, 52(7), 555-567. https://doi.org/10.1002/mc.21891