RESUMO
BACKGROUND: Aurora kinases are key regulators of cell cycle and represent new promising therapeutic targets in several human tumours. METHODS: Biological relevance of Aurora kinase-A and -B was assessed on osteosarcoma clinical samples and by silencing these genes with specific siRNA in three human osteosarcoma cell lines. In vitro efficacy of two Aurora kinases-targeting drugs (VX-680 and ZM447439) was evaluated on a panel of four drug-sensitive and six drug-resistant human osteosarcoma cell lines. RESULTS: Human osteosarcoma cell lines proved to be highly sensitive to both drugs. A decreased drug sensitivity was observed in doxorubicin-resistant cell lines, most probably related to ABCB1/MDR1 overexpression. Both drugs variably induced hyperploidy and apoptosis in the majority of cell lines. VX-680 also reduced in vitro cell motility and soft-agar cloning efficiency. Drug association experiments showed that VX-680 positively interacts with all conventional drugs used in osteosarcoma chemotherapy, overcoming the cross-resistance observed in the single-drug treatments. CONCLUSION: Aurora kinase-A and -B represent new candidate therapeutic targets for osteosarcoma. In vitro analysis of the Aurora kinases inhibitors VX-680 and ZM447439 indicated in VX-680 a new promising drug of potential clinical usefulness in association with conventional osteosarcoma chemotherapeutic agents.
Assuntos
Antineoplásicos/uso terapêutico , Aurora Quinases/antagonistas & inibidores , Neoplasias Ósseas/tratamento farmacológico , Osteossarcoma/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Adulto , Aurora Quinases/genética , Benzamidas/uso terapêutico , Neoplasias Ósseas/genética , Neoplasias Ósseas/patologia , Avaliação Pré-Clínica de Medicamentos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Terapia de Alvo Molecular/métodos , Osteossarcoma/genética , Osteossarcoma/patologia , Piperazinas/uso terapêutico , Quinazolinas/uso terapêutico , Células Tumorais Cultivadas , Adulto JovemRESUMO
BACKGROUND: Aims of this study were the validation of C-MYC involvement in methotrexate (MTX) resistance and the assessment of clinical impact of C-MYC and dihydrofolate reductase (DHFR) in osteosarcoma (OS). MATERIALS AND METHODS: The involvement of C-MYC in MTX resistance was validated with an antisense approach. C-MYC and DHFR protein levels at diagnosis were assessed by immunohistochemistry on series of patients treated with either a MTX-based protocol (IOR/OS-1; 72 patients) or with a standard four-drug regimen (ISG/SSG 1; 61 patients). RESULTS: Down-regulation of C-MYC significantly decreased the MTX resistance level of OS cells, demonstrating its causal involvement in this phenomenon. In clinical samples, a worse outcome was associated with increased levels of DHFR and C-MYC at diagnosis in the IOR/OS-1 patients and of C-MYC in the ISG/SSG 1 patients. CONCLUSIONS: Meanwhile the adverse clinical impact of DHFR overexpression appeared to be closely related to the relevance of MTX in the chemotherapeutic protocol, that of C-MYC overexpression was more general and not strictly MTX related. The assessment of C-MYC and DHFR at diagnosis, together with that of other known prognostic markers, can be considered for an early identification of subgroups of OS patients with higher risk of adverse outcome.