Drug resistance in D. discoideum: isolation of 4-nitroquinoline 1-oxide resistant mutants

Abstract

The drug 4-nitroquinoline 1-oxide (4NQO) displays both carcinogenic and antitumor effects, a well known characteristic of many chemotherapeutic drugs. In addition 4NQO shares a similar operating mechanism with the commonly used chemotherapeutic drug cisplatin. Previously, using the model organism Dictyostelium discoideum, we have shown that we can alter sensitivity to cisplatin by deleting or overexpressing enzymes in the sphingolipid metabolic pathway. Similarly, this work analyzed the cellular response to 4NQO in Dictyostelium discoideum. To study the molecular basis of 4NQO resistance in Dictyostelium, I used restriction enzyme mediated integration (REMI), a direct insertional mutagenesis approach, to isolate 4NQO resistant mutants. This study lead to the isolation of two Dictyostelium mutants showing about 1.5 to 4.5 fold more resistance than the wild-type. Using inverse PCR and DA sequencing one mutant disruption was found to be in a retrotransposon and in the second mutant the disruption was fond to be in an intergenic region between a S-adenosylmethionine-dependent methyltransferase gene and a retrotransposon. This study confirmed that Dictyostelium discoideum can be used as a model system to study the molecular basis of resistance to anticancer drugs.