RESUMO
INTRODUCTION: Radiation resistance is a major cause of death in cancer patients. Cancer cells react during radiotherapy by re-programming specific cell functions that may confer resistance to radiation. The understanding of this complex process is hindered due to the lack of appropriate study models. We describe an experimental development of a radioresistant isogenic cancer cell line, and its molecular characterization. MATERIALS AND METHODS: A431-cultured cells were irradiated for 7 month until 85 Gy. Then, a selected single cell was left to grow as stable A431-R cell line. Clonogenic assay was used to determine cell survival, the α and ß parameters of the LQ model, and the mean inactivation dose. The DNA repair ability of cells was evaluated by pulsed-field electrophoresis method. Differential effect of fractionated radiation was ultimately tested in xenografts. Furthermore, we used a wound healing assay, Western blot for EGFR, AKT and ERK1/2 and ELISA test for vascular endothelial growth factor (VEGF) secretion. Finally we explored CD44 marker and cell cycle distribution. RESULTS: The established A431-R cell line showed radiation resistance in clonogenic assays, repair of radiation-induced DNA fragmentation and xenografted tumours. The radiation resistance was associated with in vitro higher cell growth and migration, increased levels of former oncoproteins, and secretion of VEGF. CONCLUSIONS: In this model, the emergence of radiation resistance was associated with the acquisition of biological traits that support more aggressive behaviour of cancer cells. We have generated a model that will be useful for mechanistic studies and development of rational treatments against radiation resistance in cancer.
Assuntos
Carcinoma de Células Escamosas/patologia , Tolerância a Radiação , Animais , Apoptose , Western Blotting , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/radioterapia , Ciclo Celular , Movimento Celular , Proliferação de Células , Relação Dose-Resposta à Radiação , Feminino , Citometria de Fluxo , Raios gama , Humanos , Receptores de Hialuronatos/metabolismo , Camundongos , Camundongos Nus , Fenótipo , Células Tumorais Cultivadas , Fator A de Crescimento do Endotélio Vascular/metabolismo , Cicatrização , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
INTRODUCTION: The aim of this study is to determine the interobserver variability (IV) between radiation oncologists (RO) in target volume delineation for postoperative gastric cancer (GC) radiotherapy planning. MATERIALS AND METHODS: Four physicians were asked to delimitate clinical target volume (CTV) on the same 3D CT images in 9 postoperative radiochemotherapy GC patients. Instructions were given to include tumour bed, remaining stomach, anastomosis, duodenal loop and local lymph nodes. The principal variable was spatial volume discrepancy between the main observer (called "A") and other observers (all called "B"), which were compared using the mathematical formula Aâ£B/Aâ¢B, applied to the 3D CT images using Boolean operators. Analysis of variance with two random effects (observers and patients) was performed. RESULTS: Mean volumes were 1410 cm(3) for OBA, 1231 cm(3) for OB2, 734.6 cm(3) for OB3 and 1350 cm(3) for OB4. Discrepancies were 519.9±431.6 cm(3) for OB2, 652.1±294.36 cm(3) for OB3 and 225.90±237.07 cm(3) for OB4. Standard deviation ascribed to patients as random effect was 898.6 cm(3) and that ascribed to observers was 198.10 cm(3), considered as a statistically significant difference. CONCLUSIONS: A significant IV in target delineation that can be attributed to many factors depends more on patients' characteristics than RO delineating decisions.