Identification of molecular mechanisms for cellular drug resistance by combining drug activity and gene expression profiles.

Acquired drug resistance is a major problem in cancer treatment. To explore the genes involved in chemosensitivity and resistance, 10 human tumour cell lines, including parental cells and resistant subtypes selected for resistance against doxorubicin, melphalan, teniposide and vincristine, were profiled for mRNA expression of 7400 genes using cDNA microarray technology. The drug activity of 66 cancer agents was evaluated on the cell lines, and correlations between drug activity and gene expression were calculated and ranked. Hierarchical clustering of drugs based on their drug-gene correlations yielded clusters of drugs with similar mechanism of action. Genes correlated with drug sensitivity and resistance were imported into the PathwayAssist software to identify putative molecular pathways involved. A substantial number of both proapoptotic and antiapoptotic genes such as signal transducer and activator of transcription 1, mitogen-activated protein kinase 1 and focal adhesion kinase were found to be associated to drug resistance, whereas genes linked to cell cycle control and proliferation, such as cell division cycle 25A and signal transducer of activator of transcription 5A, were associated to general drug sensitivity. The results indicate that combined information from drug activity and gene expression in a resistance-based cell line panel may provide new knowledge of the genes involved in anticancer drug resistance and become a useful tool in drug development.

Activation of p53 protein in normal and in tumor cells by a novel anticancer agent CHS 828.

CHS 828, a novel cyanoguanidine, represents a new class of drugs for cancer therapy, with an unknown primary mechanism of action. It is generally known that anticancer drugs induce p53 response thereby triggering cell cycle arrest or apoptosis. We investigated the effect of CHS 828 on p53 response in normal and tumor cells and compared this effect with that exerted by conventional anticancer drugs. After 24 h of treatment with CHS 828, we observed a dose-dependent up-regulation of wild type (WT) p53 protein in human breast carcinoma MCF-7 cells as well as in normal human and mouse fibroblasts. The highest p53 increase was observed at 300 nM to 1 microM CHS 828. CHS 828 induced phosphorylation of p53 protein at Ser-15 in normal cells. However, the drug failed to induce p53 protein in mouse cells in which the poly(ADP-ribose)-1 gene (PARP-1) was disrupted even at a 30-fold higher dose and after prolonged treatment. Combined treatment of PARP-1 -/- cells by multidrug resistance modulators did not alter p53 expression. CHS 828 inhibited cell proliferation and DNA replication in the tested cells. Interestingly, DNA synthesis as well as proliferation of PARP-1 deficient cells was inhibited by drug concentrations that were approximately 3-fold lower than their conventional counterparts. Treatment of cells with CHS 828 for 48 h did not induce apoptosis.