Differential Gene Expression in Human Lung Adenocarcinomas and Squamous Cell Carcinomas

Purpose : Differential cDNA library screening was performed on 7 human lung adenocarcinomas and 7 human lung squamous cell carcinomas and their corresponding adjacent normal tissues using a human lung cDNA library constructed from the normal bronchoalveolar cells of a 72-year-old male smoker. Experimental Design : Of the 2758 clones that were differentially expressed between normal and tumor tissues in the preliminary cDNA library screening analysis, 1163 clones were confirmed by dot blot, revealing a confirmation rate of >40%. DNA of confirmed clones was sequenced and was subjected to GenBank Blast searches. RNA expression levels were then individually analyzed by semiquantitative reverse transcription-PCR. Results : Ninety-two genes/sequences were differentially expressed in adenocarcinomas and/or squamous cell carcinomas compared with their corresponding normal tissues. Several genes were underexpressed by at least 50% in both tumor types such as c-fos , decorin, α-2-macroglobulin , platelet endothelial cell adhesion molecule 1 , EGR1 , and fibronectin. Ribosomal protein S3 was underexpressed only in squamous cell carcinomas, whereas expression of hepatocyte growth factor activator inhibitor type 2 , ubiquitin-conjugating enzyme UBC9 , and clone 333E23 on chromosome Xq21.1 were altered only in adenocarcinomas. Several genes discovered recently of which the functions are unknown, such as KIAA0728 and KIAA0425 , were also differentially expressed in both adenocarcinomas and squamous cell carcinomas of the lung. Conclusions : Many of these known and novel genes may be involved in human lung tumorigenesis; therefore, additional characterization is warranted and will be beneficial to the understanding of this deadly disease.