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Regulation of pancreatic cancer growth by superoxide
Author(s) -
Du Juan,
Nelson Elke S.,
Simons Andrean L.,
Olney Kristen E.,
Moser Justin C.,
Schrock Hannah E.,
Wagner Brett A.,
Buettner Garry R.,
Smith Brian J.,
Teoh Melissa L.T.,
Tsao MingSound,
Cullen Joseph J.
Publication year - 2013
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/mc.21891
Subject(s) - biology , clonogenic assay , cell culture , oncogene , superoxide dismutase , pancreatic cancer , cell growth , cancer cell , cell , microbiology and biotechnology , cancer research , cancer , biochemistry , enzyme , cell cycle , genetics
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‐r as oncogene correlates with increased non‐mitochondrial‐generated superoxide (O 2 . − ), which could be involved in regulating cell growth contributing to tumor progression. In the H6c7 cell line and its derivatives, H6c7er‐K ras + (H6c7 cells expressing K‐ ras oncogene), and H6c7eR‐K ras T (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 O 2 . −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 O 2 . − , 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 O 2 . − , and treatment with the small molecule O 2 . −scavenger Tempol, also decreased hydroethidine fluorescence, inhibited clonogenic survival and inhibited growth of tumor xenografts. Thus, O 2 . −produced by NOX2 in pancreatic cancer cells with K‐ ras , may regulate pancreatic cancer cell growth. © 2012 Wiley Periodicals, Inc.