RESUMO
Inhibition of androgen receptor (AR) signalling represents the conventional medical management of prostate cancer. Ultimately this treatment fails because tumors develop an incurable, castrate resistant phenotype, resulting in an unmet need for new treatments in prostate cancer. The AR remains a viable therapeutic target in castrate resistant disease, such that novel ways of downregulating AR activities are attractive as potential treatments. Here we describe a mechanism by which the AR can be downregulated by the MDM2 antagonist Nutlin-3, resulting in loss of pro-survival c-FLIP gene expression and apoptosis. We additionally show that loss of c-FLIP sensitises prostate cancer cells to Nutlin-3. Finally, we demonstrate that the unrelated MDM2 antagonist Mi-63 also impinges upon AR signalling, supporting the concept of future treatment of prostate cancer with MDM2 antagonists.
Assuntos
Apoptose/efeitos dos fármacos , Apoptose/genética , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Imidazóis/farmacologia , Piperazinas/farmacologia , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Receptores Androgênicos/metabolismo , Biomarcadores , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/genética , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/genética , Citometria de Fluxo , Técnicas de Silenciamento de Genes , Humanos , Masculino , Ligação Proteica , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , UbiquitinaçãoRESUMO
Continued androgen receptor (AR) expression and signaling is a key driver in castration-resistant prostate cancer (CRPC) after classical androgen ablation therapies have failed, and therefore remains a target for the treatment of progressive disease. Here, we describe the biological characterization of AZD3514, an orally bioavailable drug that inhibits androgen-dependent and -independent AR signaling. AZD3514 modulates AR signaling through two distinct mechanisms, an inhibition of ligand-driven nuclear translocation of AR and a downregulation of receptor levels, both of which were observed in vitro and in vivo. AZD3514 inhibited testosterone-driven seminal vesicle development in juvenile male rats and the growth of androgen-dependent Dunning R3327H prostate tumors in adult rats. Furthermore, this class of compound showed antitumor activity in the HID28 mouse model of CRPC in vivo. AZD3514 is currently in phase I clinical evaluation.
Assuntos
Antagonistas de Receptores de Andrógenos/farmacologia , Antineoplásicos/farmacologia , Neoplasias de Próstata Resistentes à Castração/patologia , Piridazinas/farmacologia , Receptores Androgênicos/metabolismo , Glândulas Seminais/efeitos dos fármacos , Acetato de Abiraterona , Antagonistas de Receptores de Andrógenos/metabolismo , Androstadienos/farmacologia , Animais , Antineoplásicos/metabolismo , Benzamidas , Linhagem Celular Tumoral , Modelos Animais de Doenças , Regulação para Baixo , Ensaios de Seleção de Medicamentos Antitumorais , Regulação Neoplásica da Expressão Gênica , Células HCT116 , Humanos , Masculino , Camundongos , Camundongos Nus , Nitrilas , Feniltioidantoína/análogos & derivados , Feniltioidantoína/farmacologia , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Piridazinas/síntese química , Piridazinas/metabolismo , Ratos , Ratos Wistar , Receptores Androgênicos/genética , Glândulas Seminais/crescimento & desenvolvimento , Transdução de Sinais/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Regardless of the achievable remissions with first line hormone therapy in patients with prostate cancer (CaP), the disease escapes the hormone dependent stage to a more aggressive status where chemotherapy is the only effective treatment and no treatment is curative. This makes it very important to identify new targets that can improve the outcome of treatment. ATM and DNA-PK are the two kinases responsible for signalling and repairing double strand breaks (DSB). Thus, both kinases are pertinent targets in CaP treatment to enhance the activity of the numerous DNA DSB inducing agents used in CaP treatment such as ionizing radiation (IR). Colony formation assay was used to assess the sensitivity of hormone dependent, p53 wt (LNCaP) and hormone independent p53 mutant (PC3) CaP cell lines to the cytotoxic effect of IR and Doxorubicin in the presence or absence of Ku55933 and NU7441 which are small molecule inhibitors of ATM and DNA-PK, respectively. Flow cytometry based methods were used to assess the effect of the two inhibitors on cell cycle, apoptosis and H2AX foci formation. Neutral comet assay was used to assess the induction of DNA DSBs. Ku55933 or NU7441 alone increased the sensitivity of CaP cell lines to the DNA damaging agents, however combining both inhibitors together resulted in further enhancement of sensitivity. The cell cycle profile of both cell lines was altered with increased cell death, DNA DSBs and H2AX foci formation. This study justifies further evaluation of the ATM and DNA-PK inhibitors for clinical application in CaP patients. Additionally, the augmented effect resulting from combining both inhibitors may have a significant implication for the treatment of CaP patients who have a defect in one of the two DSB repair pathways.
