Description
Reliable clinical tests for predicting cancer chemotherapy response are not available and individual markers failed to correctly predict resistance against anticancer agents. We hypothesized that gene expression patterns attributable to chemotherapy-resistant cells can be used as a classification tool for chemoresistance and provide novel candidate genes involved in anthracycline resistance mechanisms. We contrasted the expression profiles of 4 different human tumor cell lines of gastric, pancreatic, colon and breast origin and of their counterparts resistant to the topoisomerase inhibitors daunorubicin or doxorubicin. We also profiled the sensitive parental cells treated with doxorubicin for 24h. We interrogated Affymetrix HGU133A and U95A arrays independently. We applied two independent methods for data normalization and used Prediction Analysis of Microarrays (PAM) for feature selection. In addition, we established data sets related to drug resistance by using a virtual array composed of features represented on both types of oligonucleotide arrays. We identified 71 candidate genes associated with doxorubicine/daunorubicine resistance. To validate the microarray data, we also analyzed the expression of 12 selected genes by quantitative RT-PCR or immunocytochemistry, respectively. While the comparison of drug-sensitive versus drug-resistant cells yields candidates associated with drug resistance, the 24h treatment of sensitive parental cells produced a distinct transcriptional profile related to short-term drug effects.