RESUMO
BACKGROUND: Rituximab is a chimeric monoclonal antibody against CD20. It is an established immunotherapeutic agent for non-Hodgkin's lymphoma. Even though rituximab has been used in clinics for decades, only 50% of the patients respond to rituximab therapy. To enhance the in vitro effect of rituximab, it was labeled with Iodine-131 (131I) and combined effect of 131I-rituximab and camptothecin (CPT) was studied on a tumor cell line expressing CD20. OBJECTIVE: The aim is to study the magnitude of cell killing and the underlying mechanism responsible for enhancing in vitro therapeutic efficacy. METHODS: Rituximab was labeled with 131I by the iodogen method. Raji cells were pretreated with CPT (250 nM) for an hour followed by 131I-rituximab (0.37 and 3.7 MBq) and incubated for 24 h in a humidified atmosphere of CO2 incubator at 37°C. Subsequently, Raji cells were harvested and thoroughly washed to carry out studies of cellular toxicity, apoptosis, cell cycle, and mitogen-activated protein kinase (MAPK) pathways. RESULTS: Maximal inhibition of cell proliferation and enhancement of apoptotic cell death was observed in the cells treated with the combination of CPT and 131I-rituximab, compared to controls of CPT-treated and 131I-rituximab-treated cells. Raji cells undergo G1 arrest after 131I-rituximab treatment, which leads to apoptosis and was confirmed by the downregulation of bclxl protein. Expression of p38 was decreased while an increase in phosphorylation of p38 was observed in the combination treatment of CPT and 131I-rituximab. CONCLUSIONS: It was concluded from the findings that CPT enhanced 131I-rituximab-induced apoptosis, G1 cell cycle arrest and p38 MAPK phosphorylation in Raji cells.
Assuntos
Apoptose , Linfoma de Burkitt/patologia , Camptotecina/farmacologia , Pontos de Checagem da Fase G1 do Ciclo Celular , Rituximab/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Linfoma de Burkitt/imunologia , Linfoma de Burkitt/terapia , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Humanos , Radioimunoterapia , Células Tumorais Cultivadas , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
The aim of this study was to formulate an indigenous cold kit of Ubiquicidin, UBI (29-41), for easy preparation of (99m)Tc-UBI (29-41) to be used as an infection imaging agent. A two component kit with the peptide and SnCl2 as vial 1 and optimum amount of NaOH as vial 2 was successfully formulated as seen from the consistent radiochemical and pharmaceutical purity of the product over six consecutive batches of kits. The utility of the kit could be demonstrated through in-vitro and in vivo specificity of (99m)Tc-UBI (29-41).