Development of DNA Methylation Markers for Early Detection of Lung Cancer

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In the United States, lung cancer is the leading cause of cancer death in men and women of all ethnic groups. This disease, which is mainly caused by smoking, will kill over 160,000 Americans in 2005. In 2002/2003 it was estimated that 20-25% of men and women and almost 22% of high school students smoke. Survival of lung cancer patients is very poor, largely because the disease is difficult to detect at an early stage, when it could still be cured by surgery. Advanced imaging techniques such as spiral computed tomography allow high resolution examination of the lung, but lesions that do not progress to lung cancer are very frequently observed in longtime heavy smokers. Molecular markers that could be detected in the bodily fluids of early stage lung cancer patients would be a very powerful and complementary addition to imaging techniques, that would allow the identification of true lung cancer patients from among those with suspicious lesions. DNA hypermethylation is a modification of DNA that does not change its sequence, but that alters the ability of genes to be expressed. Abnormally increased methylation is frequently observed in cancer, where it causes the silencing of genes that normally keep cell growth and cell survival in check. To date, a number of genes showing increased methylation have been identified, but many of these genes are not methylated in a high enough percentage of lung cancers to be useful as markers. Using a high-throughput system developed at USC, the Laird-Offringa laboratory has recently identified a number of very strong candidate markers that are hypermethylated in lung cancer. This proposal is aimed at validating these markers in all major types of non-small cell lung cancer using 300 archival lung specimens and 300 matched control non-tumor lung (from the same patients), as well as 100 non-lung cancers that metastasized to the lung. Lung specimens from all major ethnic groups (white, black, Hispanic/Latino and Asian/Pacific Islander) will be examined. The ability of these markers to detect lung cancer through the analysis of patient bodily fluids will be determined using a new quantitative technique to examine the plasma, sputum and/or bronchioalveloar wash of 300 lung cancer patients treated at University Hospital, Morris Cancer Center, and Los Angeles County Hospital. The development of sensitive and specific molecular markers for lung cancer is the key to early detection of this disease, and could greatly increase lung cancer patient survival.