Demonstration of differential gene expression between sensitive and resistant ovarian tumor cells by fluorescence differential display-PCR analysis

Chemotherapy plays a major role in cancer management; however, acquired drug resistance remains a significant problem for ovarian cancer treatment. Chemoresistance is regulated by the coordinated expression of a set of genes. Thus, the identification of genes specifically modulated in the process provides an important step toward the discovery of underlying molecular mechanisms in drug resistance events. We recently developed five drug-resistant human ovarian carcinoma cell lines, including two cisplatin (cis) resistant cell lines, two carboplatin (car) resistant cell lines and one taxol (tax) resistant cell line. In this study, we investigated differential gene expression between these resistant cell lines and their parental cell lines by the fluorescence differential display-polymerase chain reaction (FDD-PCR) technique. We first screened and identified differentially expressed genes in the resistant ovarian cancer cell lines, and we then sequenced and analyzed these genes by bioinformatics software. A total of 33 fragments were displayed in the two resistant cell lines (S-cis and S-car) derived from the sensitive SKOV-3 cell line, and 36 fragments were displayed in the three resistant cell lines (A-cis, A-car and A-tax) derived from the sensitive A2780 cell line. After purification, cloning, sequencing, and homology analysis on the NCBI BLAST GenBank, 12 gene fragments were identified from the resistant S-cis and S-car cells, and 23 gene fragments were identified from the resistant A-cis, A-car and A-tax cells. Although a homolog search of the NIH GenBank revealed that most of the gene fragments were not significantly associated with the known drug resistance-related genes, our study conclusively demonstrates that FDD-PCR is a useful tool for analyzing the differential gene expression between resistant and sensitive tumor cells and for identifying novel chemoresistance-associated genes and potential biological markers or genetic markers of drug resistance.