RESUMO
Millingtonia hortensis is a medicinal plant widely used in many Asian countries. An aqueous crude extract of this plant has been shown the apoptosis induction on RKO colon cancer cells. However, its mechanism remains unknown. To learn more about this plant extract, we partially purified the crude extract using Sephadex LH-20 and three aqueous fractions were collected. Each fraction was investigated for cytotoxicity using MTT assay. Fraction 1 showed antiproliferative effect on RKO cells with dose-dependent manner, while fraction 2 and 3 had no effect. Induction of apoptosis was determined using flow cytometry and DNA fragmentation method. Apoptotic cell numbers and the appearance of fragmented DNA increased with dose-dependent manner after treatment with fraction 1 for 48 h. We further investigated the expression of apoptotic protein by western blot analysis. Fraction 1 decreased the expression of anti-apoptotic protein, Bcl-xL and p-Bad, while pro-apoptotic protein Bad, was not changed. Fraction 1 also decreased the expression of p-Akt and slightly increased the level of total Akt. These results indicated that fraction 1 is able to inhibit cell proliferation and induce apoptosis on RKO cells by decreasing the expression of Bcl-xL, p-Bad and p-Akt which are involving in survival of cancer cells.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Neoplasias do Colo/tratamento farmacológico , Flavonoides/farmacologia , Fitoterapia/métodos , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Proliferação de Células/efeitos dos fármacos , Neoplasias do Colo/patologia , Neoplasias do Colo/prevenção & controle , Fragmentação do DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Citometria de Fluxo , Regulação Neoplásica da Expressão Gênica , Humanos , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Células Tumorais CultivadasRESUMO
Millingtonia hortensis is an important medicinal plant in Southeast Asia, used for the treatment of asthma, sinusitis and as a cholagogue and tonic. The aim of this study was to compare the effects of aqueous and ethanol extracts of Millingtonia hortensis on the induction of apoptosis in an RKO human colon cancer cell line. Viability of RKO cells was assessed by MTT reduction assay. The aqueous extract, but not the ethanol extract of M. hortensis inhibited cell growth and proliferation in a dose- and time-dependent manner. Apoptotic cells were determined by flow cytometry and DNA fragmentation assay. Apoptotic cell numbers increased in a dose-dependent manner after treatment with aqueous extract. DNA ladders were clearly observed in RKO cells treated with 200, 300 and 400 ?g/ml of the aqueous extract of M. hortensis for 48 h. These results indicate that the aqueous extract of M. hortensis inhibited cell proliferation in an RKO colon cancer cell line via the apoptosis pathway.
