RESUMO
Few therapeutic treatment options are available for patients suffering from metastatic androgen-independent prostate cancer. We investigated the ability of the estrogen metabolite 2-methoxyestradiol to inhibit the proliferation of a variety of human prostate cancer cell lines in vitro and to inhibit the growth of androgen-independent prostate cancer in a transgenic mouse model in vivo. Our results showed that 2-methoxyestradiol is a powerful growth inhibitor of LNCaP, DU 145, PC-3, and ALVA-31 prostate cancer cells. Cell flow cytometry of 2-methoxyestradiol-treated DU 145 cells showed a marked accumulation of cells in the G2/M phase of the cell cycle and an increase in the sub-G1 fraction (apoptotic). In addition, staining for annexin V, changes in nuclear morphology, and inhibition of caspase activity support a role for apoptosis. More importantly, we showed that 2-methoxyestradiol inhibits prostate tumor progression in the Ggamma/T-15 transgenic mouse model of androgen-independent prostate cancer without toxic side effects. These results in cell culture and an animal model support investigations into the clinical use of 2-methoxyestradiol in patients with androgen-independent prostate cancer.
Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Estradiol/farmacologia , Fase G2/efeitos dos fármacos , Mitose/efeitos dos fármacos , Neoplasias da Próstata/tratamento farmacológico , 2-Metoxiestradiol , Administração Oral , Clorometilcetonas de Aminoácidos/farmacologia , Animais , Anexina A5/análise , Antineoplásicos/administração & dosagem , Inibidores de Caspase , Divisão Celular/efeitos dos fármacos , Núcleo Celular/efeitos dos fármacos , Modelos Animais de Doenças , Progressão da Doença , Relação Dose-Resposta a Droga , Implantes de Medicamento , Resistencia a Medicamentos Antineoplásicos , Inibidores Enzimáticos/farmacologia , Estradiol/administração & dosagem , Estradiol/análogos & derivados , Citometria de Fluxo , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Neoplasias da Próstata/química , Neoplasias da Próstata/patologia , Células Tumorais CultivadasRESUMO
The transgenic mouse line Ggamma/T-15 containing the fetal globin promoter linked to SV40 T antigen unexpectedly results in androgen-independent prostate carcinomas. Given the key role of GATA-1 transcription factor in fetal globin gene promoter activity, we investigated whether specific GATA family members are expressed in the prostate and whether they can regulate prostate-specific genes. We found that GATA-2 and -3 are the predominant GATA family members expressed in human and mouse prostate and that GATA mRNA levels are not regulated by androgen. We identified six GATA sites flanking an androgen-response element located in the far-upstream enhancer of the prostate-specific antigen (PSA) gene. These GATA sites are targets for GATA factors and are essential for optimal androgen induction of transfected PSA enhancer/promoter plasmids in LNCaP, a PSA and androgen receptor expressing human prostate cancer cell line. Our results suggest that prostatic GATA-2 and -3 are involved in the androgen regulation of the PSA gene.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Elementos Facilitadores Genéticos/genética , Regiões Promotoras Genéticas/genética , Antígeno Prostático Específico/genética , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , Animais , Neoplasias da Mama , Proteínas de Ligação a DNA/genética , Eletroforese em Gel de Poliacrilamida , Feminino , Fator de Transcrição GATA2 , Fator de Transcrição GATA3 , Fator de Transcrição GATA6 , Regulação da Expressão Gênica , Genes Reporter , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Mutagênese Sítio-Dirigida , Neoplasias da Próstata , Ligação Proteica , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transativadores/genética , Fatores de Transcrição/genética , Células Tumorais Cultivadas , Sistema Urogenital/crescimento & desenvolvimento , Sistema Urogenital/metabolismo , Dedos de Zinco/genéticaRESUMO
Expression of MET, the receptor for hepatocyte growth factor (HGF), has been associated with androgen-insensitive prostate cancer. In this study we evaluated MET activation by HGF and HGF action in prostate cancer cell lines. HGF causes phosphorylation (activation) of the MET receptor in three androgen-unresponsive cell lines (DU 145, PC-3, and ALVA-31) together with morphological change. Although HGF is known to stimulate the growth of normal epithelial cells, including those from prostate, we found that HGF inhibited ALVA-31 and DU 145 (hormone-refractory) cell lines. Moreover, HGF and vitamin D additively inhibited growth in each androgen-unresponsive cell line, with the greatest growth inhibition in ALVA-31 cells. Further studies in ALVA-31 cells revealed distinct cooperative actions of HGF and vitamin D. In contrast to the accumulation of cells in G1 seen during vitamin D inhibition of androgen-responsive cells (LNCaP), growth inhibition of the androgen-unresponsive ALVA-31 cell line with the HGF and vitamin D combination decreased, rather than increased, the fraction of cells in G1, with a corresponding increase in the later cell cycle phases. This cell cycle redistribution suggests that in androgen-unresponsive prostate cancer cells, HGF and vitamin D act together to slow cell cycle progression via control at sites beyond the G1/S checkpoint, the major regulatory locus of growth control in androgen-sensitive prostate cells.
