RESUMEN
PURPOSE: Novel molecularly targeted agents, given in combination with radiotherapy, have the potential to increase tumor response rates and the survival of patients with lung cancer. AZD6244 is a potent and selective inhibitor of mitogen-activated protein kinase (MAPK) kinase 1/2 (MEK1/2), a critical enzyme within the MAPK/extracellular signal-regulated kinase (ERK) signaling pathway that regulates the proliferation and survival of tumor cells. EXPERIMENTAL DESIGN: This study examined the potential benefit of combining AZD6244 with fractionated radiotherapy using human lung and colon carcinoma xenograft models. RESULTS: AZD6244 reduced ERK phosphorylation in Calu-6 lung cancer cells in vitro. Administration of AZD6244 for 10 days (25 mg/kg twice daily p.o.) inhibited the tumor growth of Calu-6 xenografts, with regrowth occurring on cessation of drug treatment. When fractionated tumor-localized radiotherapy (5 x 2 Gy) was combined with AZD6244 treatment, the tumor growth delay was enhanced significantly when compared with either modality alone, and this effect was also seen in a colon tumor model. We examined the effect of inhibiting MEK1/2 on the molecular responses to hypoxia, a potential interaction that could contribute to radioresponsiveness. AZD6244 reduced hypoxia-inducible factor-specific transactivation in vivo, shown using Calu-6 dual clone cells that stably express a Firefly luciferase gene under the control of a hypoxia-driven promoter. Furthermore, hypoxia-inducible factor-1 alpha, GLUT-1, and vascular endothelial growth factor levels were reduced by AZD6244, and there was a significant decrease in vascular perfusion in the tumors given combination treatment when compared with the other treatment groups. CONCLUSIONS: These data provide support for the clinical development of AZD6244 in combination with radiotherapy and indicate a potential role for AZD6244 in inhibiting the tumor hypoxia response.
Asunto(s)
Bencimidazoles/farmacología , Neoplasias Colorrectales/radioterapia , Neoplasias Pulmonares/radioterapia , MAP Quinasa Quinasa 2/antagonistas & inhibidores , Inhibidores de Proteínas Quinasas/farmacología , Fármacos Sensibilizantes a Radiaciones/farmacología , Animales , Hipoxia de la Célula/efectos de los fármacos , Línea Celular Tumoral , Evaluación de Medicamentos , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Femenino , Humanos , MAP Quinasa Quinasa 1 , Ratones , Proteína Quinasa 1 Activada por Mitógenos/antagonistas & inhibidores , Virus de la Neumonía Murina , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
The resistance of hypoxic cells to conventional chemotherapy is well documented. Using both adenovirus-mediated gene delivery and small molecules targeting hypoxia-inducible factor-1 (HIF-1), we evaluated the impact of HIF-1 inhibition on the sensitivity of hypoxic tumor cells to etoposide. The genetic therapy exploited a truncated HIF-1alpha protein that acts as a dominant-negative HIF-1alpha (HIF-1alpha-no-TAD). Its functionality was validated in six human tumor cell lines using HIF-1 reporter assays. An EGFP-fused protein demonstrated that the dominant-negative HIF-1alpha was nucleus-localized and constitutively expressed irrespective of oxygen tension. The small molecules studied were quinocarmycin monocitrate (KW2152), its analog 7-cyanoquinocarcinol (DX-52-1), and topotecan. DX-52-1 and topotecan have been previously established as HIF-1 inhibitors. HT1080 and HCT116 cells were treated with either AdHIF-1alpha-no-TAD or nontoxic concentrations (0.1 microM; Asunto(s)
Resistencia a Antineoplásicos
, Factor 1 Inducible por Hipoxia/antagonistas & inhibidores
, Neoplasias/tratamiento farmacológico
, Adenoviridae/genética
, Antineoplásicos Fitogénicos/uso terapéutico
, Hipoxia de la Célula
, Línea Celular Tumoral
, Núcleo Celular/química
, Resistencia a Antineoplásicos/efectos de los fármacos
, Etopósido/uso terapéutico
, Vectores Genéticos/genética
, Proteínas Fluorescentes Verdes/análisis
, Proteínas Fluorescentes Verdes/genética
, Humanos
, Factor 1 Inducible por Hipoxia/genética
, Subunidad alfa del Factor 1 Inducible por Hipoxia/análisis
, Subunidad alfa del Factor 1 Inducible por Hipoxia/genética
, Isoquinolinas/farmacología
, Oxígeno/metabolismo
, Eliminación de Secuencia
, Topotecan/farmacología
, Activación Transcripcional