RESUMO
Resistance to chemotherapy is responsible for a failure of current treatment regimens in cancer patients. We have reported previously that the Y-box protein YB-1 regulates expression of the P-glycoprotein gene mdr1, which plays a major role in the development of a multidrug resistant-tumor phenotype. YB-1 predicts drug resistance and patient outcome in breast cancer. Thus, YB-1 is a promising target for new therapeutic approaches to defeat multidrug resistance. In drug-resistant cancer cells and in adenovirus-infected cells YB-1 is found in the nucleus. Nuclear accumulation of YB-1 in adenovirus-infected cells is a function of the E1 region, and we have shown that YB-1 facilitates adenovirus replication. Here we report that E1A-deleted or mutant adenovirus vectors, such as Ad312 and Ad520, replicate efficiently in multidrug-resistant (MDR) cancer cells and induce an adenovirus cytopathic effect resulting in host cell lysis. Thus, replication-defective adenoviruses are a previously unrecognized vector system for a selective elimination of MDR cancer cells. Our work forms the basis for the development of novel oncolytic adenovirus vectors for the treatment of MDR malignant diseases in the clinical setting.
Assuntos
Proteínas E1A de Adenovirus/genética , Resistência a Múltiplos Medicamentos , Terapia Genética/métodos , Replicação Viral/genética , Adenovírus Humanos/genética , Adenovírus Humanos/isolamento & purificação , Sequência de Bases , Linhagem Celular , Linhagem Celular Tumoral , Primers do DNA , DNA Complementar/genética , Deleção de Genes , Células HeLa , Humanos , Neoplasias/genética , Neoplasias/terapia , Transfecção/métodosRESUMO
Elevated expression of the heparan sulphate proteoglycan glypican-3 (GPC3) was found on mRNA and protein levels in the atypical multidrug-resistant gastric carcinoma cell line EPG85-257RNOV, which was established by in vitro selection against mitoxantrone. In order to elucidate a putative role of GPC3 in the drug-resistant phenotype, the mitoxantrone-resistant cell line EPG85-257RNOV was transfected with an expression vector construct carrying an anti-GPC3 hammerhead ribozyme. It could be demonstrated that in anti-GPC3 ribozyme-transfected cell clones, the GPC3-specific mRNA and corresponding protein expression levels were decreased to levels that are similar to those observed in nonresistant, parental cells. The anti-GPC3 ribozyme-containing clones reduced the mitoxantrone resistance level up to 21% of the original resistance and the crossresistance against etoposide to 33% of the original value. This reversal of drug resistance was accompanied by an increased cellular mitoxantrone accumulation in the anti-GPC3 ribozyme-expressing cells. In conclusion, it was verified that GPC3 is involved in the cellular protection against mitoxantrone in the atypical multidrug-resistant gastric carcinoma cell line EPG85-257RNOV.