Journal Article

Map kinase activation correlates with K-<i>ras</i> mutation and loss of heterozygosity on chromosome 6 in alveolar bronchiolar carcinomas from B6C3F1 mice exposed to vanadium pentoxide for 2 years

Theodora R. Devereux, Wanda Holliday, Colleen Anna, Nancy Ress, Joseph Roycroft and Robert C. Sills

in Carcinogenesis

Volume 23, issue 10, pages 1737-1743
Published in print October 2002 | ISSN: 0143-3334
Published online October 2002 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/23.10.1737
Map kinase activation correlates with K-ras mutation and loss of heterozygosity on chromosome 6 in alveolar bronchiolar carcinomas from B6C3F1 mice exposed to vanadium pentoxide for 2 years

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Previous work showed a correlation between K-ras mutation and loss of heterozygosity (LOH) on chromosome 6 in the region of K-ras in lung carcinomas from B6C3F1 mice. We hypothesized that mitogen-activated protein kinase (MAPK) would be activated only in those lung neoplasms with both K-ras mutation and LOH. As MAPK activity can be correlated directly with signal detection using antibodies to phosphorylated MAPK, we were able to analyze lung carcinomas from B6C3F1 mice for the presence or absence of MAPK activity by western analysis. Vanadium pentoxide-induced mouse lung carcinomas, which had been shown to have a high frequency of K-ras mutations and LOH on chromosome 6 and for which frozen tumor tissue was available, were used for this study. Total MAPK expression levels were similar between normal lung and lung carcinomas. Phospho-MAPK was elevated in five of six lung carcinoma samples examined in which K-ras mutations and chromosome 6 LOH were identified and in four of five carcinomas with K-ras mutations that lacked LOH. Phospho-MAPK was undetectable or weakly expressed in seven carcinomas examined without K-ras mutations and in normal lung. By immunohistochemistry three K-ras positive/LOH negative samples exhibited multifocal areas of nuclear and cytoplasmic staining for phospho-MAPK. Large amounts of non-staining fibroblasts, lymphocytes and macrophages were also observed in these tumors. Two of these lung carcinomas were microdissected and chromosome 6 LOH was detected in regions of phospho-MAPK positive cells. These results suggest that MAPK is activated during vanadium pentoxide-induced B6C3F1 mouse lung tumorigenesis following K-ras mutation and loss of the wild-type K-ras allele.

Keywords: LOH, loss of heterozygosity; MAPK, mitogen-activated protein kinase; SOS, sodium dodecyl sulfate; SSCP, single-strand conformation polymorphism.

Journal Article.  5087 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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