Direct isolation of variably amplified cdnas from human tumor-cell lines

Gene amplification is an important phenomenon in the pathogenetics of malignancy. A method is defined which allows the determination of gene amplification from any sample from which RNA can be obtained, and requires no a priori knowledge of the cytogenetic or genomic state of the tumor. This method allows the determination of various degrees of amplification, and is sensitive to lower degrees of increased copy number. Gene amplification from cell lines with known oncogene amplification of 13- and 7-fold could be detected. Hence, use of a simple modified subtractive hybridization technique can identify amplified cDNAs from tissue without detailed previous genomic knowledge of the samples. This methodology should prove useful in the assessment of disorders where copy number changes of expressed genes are present.