Grants and Contracts Details
Description
Lung cancer is the most lethal cancer in the United States and Kentucky is the leading
state for lung cancer death in the nation. However, the molecular basis of the deadly disease
is still unknown. Previous studies have shown that lung cancer is often associated with
deletion of chromosome 3p, where a mismatch repair (MMR)gene, MLH1, is located.
Recently, a substantial fraction of lung cancer have been shown to manifest frequent
alterations in simple repetitive sequences (also called microsatellite instability), a phenotype
that was initiaJlyidentified in hereditary non-polyposis colorectal cancer and was caused by
loss of function in a genome maintenance pathway called MMR. These findings strongly
suggest a close association of lung cancer with MMRdefects. To test this hypothesis, this
application will utilize both genetic and biochemical approaches to analyze relationship
between lung cancer and MMRdeficiency. First, lung tumors willbe screened for
microsatellite instability (MSI), and tumors with MSI willbe examined for expression of two
important MMRgenes, MSH2 and MLH1, by immunohistochemistry. Specific
alterations/mutations willbe determined in tumors lacking expression of MSH2 or MLH1
using the combined technology of PCR, single strand conformation polymorphism, and DNA
sequencing analysis. Second, individual alterations identified willbe introduced into the
MSH2 or MLH1 baculovirual clones by site-directed mutagenesis. To determine actual
impact of these alterations on lung carcinogenesis and MMRfunction, the mutant
baculovirual recombinant proteins willbe examined for their ability to restore MMRto known
MSH2 or MLH1 mutant extracts using an in vitro functional assay. Finally, tumors lacking
MLH1 expression willbe analyzed for hypermethylation of the MLH1 promoter, whose
methylation has been shown to transcriptionally silence the MLH1 expression in other
cancers. Based on our preliminarystudies, we believe that both deletions and point
mutations of MMR genes will be identified in lung cancers, and this study will provide useful
inforr~ation for lung cancer etiology, early detection, and treatment.
Status | Finished |
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Effective start/end date | 7/1/02 → 6/30/05 |
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