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Journal of Cancer Epidemiology
Volume 2008, Article ID 215809, 8 pages
http://dx.doi.org/10.1155/2008/215809
Research Article

Genetic and Epigenetic Tumor Suppressor Gene Silencing Are Distinct Molecular Phenotypes Driven by Growth Promoting Mutations in Nonsmall Cell Lung Cancer

1Department of Pathology and Laboratory Medicine, Center for Environmental Health and Technology, Brown University, Providence, RI 02912, USA
2Department of Community Health, Center for Environmental Health and Technology, Brown University, Providence, RI 02912, USA
3Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA
4Division of Epidemiology and Community Health, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA

Received 10 January 2008; Accepted 16 December 2008

Academic Editor: Cornelia Ulrich

Copyright © 2008 Carmen J. Marsit et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Both genetic and epigenetic alterations characterize human nonsmall cell lung cancer (NSCLC), but the biological processes that create or select these alterations remain incompletely investigated. Our hypothesis posits that a roughly reciprocal relationship between the propensity for promoter hypermethylation and a propensity for genetic deletion leads to distinct molecular phenotypes of lung cancer. To test this hypothesis, we examined promoter hypermethylation of 17 tumor suppressor genes, as a marker of epigenetic alteration propensity, and deletion events at the 3p21 region, as a marker of genetic alteration. To model the complex biology between these somatic alterations, we utilized an item response theory model. We demonstrated that tumors exhibiting LOH at greater than 30% of informative alleles in the 3p21 region have a significantly reduced propensity for hypermethylation. At the same time, tumors with activating KRAS mutations showed a significantly increased propensity for hypermethylation of the loci examined, a result similar to what has been observed in colon cancer. These data suggest that NSCLCs have distinct epigenetic or genetic alteration phenotypes acting upon tumor suppressor genes and that mutation of oncogenic growth promoting genes, such as KRAS, is associated with the epigenetic phenotype.