Purpose: We examined the usability of a newly developed, compact-sized DNA array filter for studying the gene expression pattern of individual colorectal cancer.
Methods: Complementary DNA probes were prepared from mRNA extracted from colonic cancer specimens and adjacent normal mucosa and then were labeled with chemiluminescence. These labeled probes were allowed to bind to the gene fragments on the filter. A specialized scanning charge-coupled device camera measured the intensity of each chemiluminescent spot, which is an indicator of the degree to which a specific gene is expressed. Gene expression image was quantified into intensity of signals by using computer software.
Results: Characteristic gene expression patterns were obtained from the colonic cancer cell line, RPMI4788, and the leukemia cell line, HL60, by using this compact-sized DNA array filter in the preliminary experiment. Up-regulation of nm23, TIMP1, VEGF, and cyclin E and down-regulation of some tumor suppressor genes (p53, TOSO, and SIVA), beta-catenin, and metallothionein were observed in colonic cancer specimen when compared with those of normal mucosa.
Conclusions: We have obtained unique gene expression patterns from colorectal cancer and normal tissue by using a newly developed compact-sized DNA array filter system. Collecting, storing, and analyzing of gene expression data from many samples of colorectal cancer will enable us to identify distinct subsets of patients based on molecular characteristics in the near future.