Simultaneous analysis of 1176 gene products in normal human aorta and abdominal aortic aneurysms using a membrane-based complementary DNA expression array

Background: A number of changes in gene expression have been described in a bdominal aortic aneurysms (AAAs), but the spectrum of molecular alterations in this disease is un]known. The purpose of this study was to characterize the expression of approximately 1000 gene products in human AAA tissue and to compare the profile of genes expressed in AAAs with that observed in no rmal aorta. Materials and Methods Total RNA was isolated from abdominal aortic wall tis sues (4 AAAs and 4 normal aortas), and array-specific [P-32]-labeled comple mentary DNA (cDNA) probes were created with reverse transcription. The cDNA probes were hybridized with nylon membranes containing an array of 1176 cD NA clones (AtlasArray Human 1.2 I; Clontech, Pale Alto, Calif), and autorad iographs were scanned to identify the patterns of gene expression character istic of each tissue type. Densitometric analysis was used to standardize t he expression of individual genes to a panel of housekeeping controls, and differential gene expression was defined by a signal ratio of at least 2:1. Results: One hundred forty-five (12.3%) of the 1176 genes were consistently expressed in aortic tissue. Thymosin beta -4 was the most abundant of 101 transcripts detected in both AAAs and normal aorta, whereas 44 genes exhibi ted differential patterns of expression (39 predominant in AAAs and 5 in no rmal aorta). Densitometric analysis confirmed differences in expression for 20 of these gene products between AAAs and normal aorta, with the greatest increases seen for myeloid cell nuclear differentiation antigen (31-fold), cathepsin H (30-fold), platelet-derived growth factor-A (23-fold), apolipo protein E (13-fold), gelatinase B/matrix metalloproteinase-9 (12-fold), and interleukin-8 (11-fold). The only gene products substantially decreased in AAAs were myosin light chain kinase (39-fold) and beta -1 integrin (twofol d). AAA tissues thereby exhibited a distinct pattern of gene expression ref lecting chronic inflammation, extracellular matrix degradation, atheroscler osis, and smooth muscle cell depletion. Conclusion: cDNA expression arrays provide a powerful new approach to help identify the molecular mechanisms responsible for aneurysmal degeneration. Further studies will be needed to elucidate the functional and pathophysiol ogic significance of the individual genes that exhibit altered levels of ex pression in AAA tissue.