Regulation of pancreatic cancer growth by superoxide
| Autor: | 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 |
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| Rok vydání: | 2011 |
| Předmět: |
Blotting
Western Mice Nude Fluorescence Article Cyclic N-Oxides Proto-Oncogene Proteins p21(ras) Mice Cytosol Superoxides Proto-Oncogene Proteins Tumor Cells Cultured Animals Humans RNA Small Interfering Tumor Stem Cell Assay Cell Proliferation Membrane Glycoproteins Superoxide Dismutase NADPH Oxidases Mitochondria Phenanthridines Pancreatic Neoplasms NADPH Oxidase 2 ras Proteins Spin Labels Extracellular Space |
| Zdroj: | Molecular carcinogenesis. 52(7) |
| ISSN: | 1098-2744 |
| Popis: | 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 (O 2.-), 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 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. |
| Databáze: | OpenAIRE |
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