RESUMO
Solid tumors contain normoxic and hypoxic regions depending on the distance from the capillary. Normal cells may also be exposed to hypoxia under certain physiological conditions. Tumor hypoxia has been shown to associate strongly with tumor propagation and malignant progression. Hypoxia-inducible factor (HIF)-1alpha is stable under hypoxia and induces transcription of target genes by binding to the hypoxia-response element (HRE). Here we investigated the oncolytic effects of a novel adenovirus mutant with a deleted E1B55 gene (Ad.Delta55.HRE), in which the expression of E1A, which is essential for adenoviral replication, is regulated under the control of an HRE-expression system. Ad.Delta55.HRE expressed E1A under normoxia and more E1A under hypoxia and exhibited oncolytic effects on various cultured tumor cells, but its cytotoxic effect is relatively attenuated in normal fibroblast cells under normoxic and hypoxic conditions. Ad.Delta55.HRE lysed Huh-7 hepatoma cells stably expressing HIF-1alpha more effectively compared to parental cells. Ad.Delta55.HRE treatment exhibited significant antitumor activity in PC-3 prostate- and MDA-MB-435 breast tumor-bearing nude mice in which HIF-1alpha protein was immunohistochemically detected. The E1A and hexon proteins of adenovirus were immunostained in MDA-MB-435 xenografts after Ad.Delta55.HRE treatment, suggestive of viral replication. Our results suggest that Ad.Delta55.HRE may be useful for the treatment of solid tumors.
Assuntos
Adenoviridae/genética , Proteínas E1A de Adenovirus/genética , Terapia Genética/métodos , Vetores Genéticos/genética , Neoplasias/terapia , Proteínas E1A de Adenovirus/análise , Proteínas E1B de Adenovirus/genética , Proteínas E1B de Adenovirus/metabolismo , Animais , Proteínas do Capsídeo/análise , Hipóxia Celular , Linhagem Celular Tumoral , Sobrevivência Celular , Deleção de Genes , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia , Camundongos , Transplante de Neoplasias , Regiões Promotoras Genéticas/genética , Elementos de Resposta/genética , Fatores de Transcrição/análise , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Replicação Viral/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The direct effects of estradiol-17beta (E(2)) on phosphate (P(i)) uptake and on DNA synthesis in the primary rabbit kidney proximal tubule cells (PTCs) have been investigated. In the present study, E(2) (>10(-9) M, over 9 days) causes an increase both in [(3)H]thymidine incorporation and the number of PTCs. The anti-estrogen tamoxifen completely prevented the E(2)-induced increase in [(3)H]thymidine incorporation, and ameliorated the stimulatory effect of E(2) on growth. E(2) (>10(-9 )M, over 5 days) also stimulated the P(i) uptake and its effect was due to the V(max) values but not to the K(m) value for P(i) uptake. Estriol and estrone also exerted significant stimulatory effects on P(i) uptake. Progesterone, tamoxifen, actinomycin D and cycloheximide prevented the E(2)-induced stimulation of P(i) uptake. In conclusion, estrogens at physiological concentrations stimulate P(i) uptake and DNA synthesis in the renal proximal tubule cells, and these effects are estrogen receptor mediated.
