Discovery of differentially expressed genes associated with paclitaxel resistance using cDNA array technology: Analysis of interleukin (IL) 6, IL-8, and monocyte chemotactic protein 1 in the paclitaxel-resistant phenotype

In an attempt to define the molecular changes associated with the paclitaxe l-resistant phenotype in human cancer, a paclitaxel-resistant ovarian cance r cell Line, SKOV-3(TR), was established through stepwise selection in incr easing paclitaxel concentrations. SROV-3(TR) was cross- resistant to doxoru bicin and vincristine and overexpressed multidrug resistance gene 1 but not multidrug resistance associated protein. SKOV-3(TR) and the paclitaxel-sen sitive SKOV-3 parent line were characterized using human cDNA array technol ogy that examined expression of a wide variety of genes involved in cell gr owth, signal transduction, cell death, and immune function. cDNA probes fro m reverse transcribed mRNAs of both paclitaxel-resistant and parent cells w ere compared to identify genes differentially expressed in the paclitaxel-r esistant cells. Of 588 different human cDNA transcripts compared, 6 genes w ere found to be markedly decreased, and 12 genes increased in the resistant subline. Northern analysis and/or reverse transcription-PCR confirmed that 12 of these 18 genes were over- or underexpressed in SKOV-3(TR), In additi on, at Least eight of the genes were found differentially expressed in seve ral other paclitaxel- and/or doxorubicin-resistant cell lines, both those w ith increased multidrug resistance expression and those without. Included i n the set of overexpressed genes were the cytokines/chemokines interleukin 6, interleukin 8, and monocyte chemotactic protein 1, ELISA assays confirm that mRNA overexpression of these cytokine/chemokines was associated with t he increased secretion of these molecules in the tissue culture supernatant . Evaluation of supernatants from an expanded collection of paclitaxel- and Adriamycin-resistant cell lines demonstrated that all of the resistant lin es had significant overexpression of at least one cytokine/chemokine as com pared with their drug-sensitive parent line. The overexpression of these cy tokines seemed to be stable and associated with a drug-resistant phenotype with only a modest induction of cytokine expression in the parent line with short-term paclitaxel exposure. These findings suggest that the developmen t of paclitaxel resistance is accompanied by multiple changes in gene expre ssion including stable alterations in selective chemokine and cytokine expr ession. The role these associated genetic changes have in the drug-resistan t phenotype is discussed.