RESUMO
BACKGROUND/AIMS: A major polyphenol of green tea, epigallocatechin-3-gallate (EGCG), has previously been shown to induce cell-cycle arrest and apoptosis in various cancers. However, little is known about its effects on hepatocellular carcinomas (HCCs). METHODS: Four HCC cell lines, HLE, HepG2, HuH-7 and PLC/PRF/5, were treated with EGCG or vehicle. Cell viability was assessed by trypan blue staining and WST-8 assay. Cell-cycle, apoptosis and apoptosis-related proteins in HLE cells were evaluated by flow cytometry and Western blotting. The effect of EGCG was also studied in vivo using a xenograft model. The effect of co-treatment with EGCG and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was also assessed. RESULTS: EGCG inhibited the growth of all HCC cell lines at concentrations of 50-100 microg/ml. In HLE cells, EGCG induced apoptosis but not cell-cycle arrest and appears to have down-regulated Bcl-2alpha and Bcl-xl by inactivation of NF-kappaB. Oral administration of EGCG showed similar effects in HLE xenograft tumors. Co-treatment with EGCG and TRAIL synergistically induced apoptosis in HLE cells. CONCLUSIONS: EGCG induced apoptosis in HLE cells, both in vitro and in vivo. Moreover, it enhanced TRAIL-induced apoptosis. Therefore, EGCG treatment may be useful for improving the prognosis of HCCs.
Assuntos
Anticarcinógenos/uso terapêutico , Carcinoma Hepatocelular/tratamento farmacológico , Catequina/análogos & derivados , Neoplasias Hepáticas/tratamento farmacológico , Proteína X Associada a bcl-2/metabolismo , Proteína bcl-X/metabolismo , Administração Oral , Animais , Anticarcinógenos/análise , Apoptose , Proteínas Reguladoras de Apoptose/uso terapêutico , Camellia sinensis/química , Carcinoma Hepatocelular/metabolismo , Caspases/metabolismo , Catequina/análise , Catequina/uso terapêutico , Linhagem Celular Tumoral , Regulação para Baixo , Ativação Enzimática , Humanos , Neoplasias Hepáticas/metabolismo , Masculino , Glicoproteínas de Membrana/uso terapêutico , Camundongos , Camundongos Endogâmicos , RNA Mensageiro/análise , RNA Mensageiro/metabolismo , Ligante Indutor de Apoptose Relacionado a TNF , Chá/química , Fator de Necrose Tumoral alfa/uso terapêutico , Ensaios Antitumorais Modelo de Xenoenxerto , Proteína X Associada a bcl-2/genética , Proteína bcl-X/genéticaRESUMO
Proviral tagging has been used in animals as a powerful tool for cancer genetics. We show that a similar approach is possible in patients with hepatocellular carcinoma (HCC) infected by Hepatitis B Virus (HBV), a human pararetrovirus which may act by insertional mutagenesis. In this work, the HBV genome is used as a probe to identify cancer-related genes. By using HBV-Alu-PCR, we obtained 21 HBV/cellular DNA junctions from 18 different patients. In six of 21, we found the HBV DNA integrated into a cellular gene: (1) Sarco/Endoplasmic Reticulum Calcium ATPase1 Gene; (2) Thyroid Hormone Receptor Associated Protein 150 alpha Gene; (3) Human Telomerase Reverse Transcriptase Gene; (4) Minichromosome Maintenance Protein (MCM)-Related Gene; (5) FR7, a new gene expressed in human liver and cancer tissues; and (6) Nuclear Matrix Protein p84 Gene. Seven junctions contained unique cellular sequences. In the remaining eight, the HBV DNA was next to repetitive sequences, five of them of LINE1 type. The cellular genes targeted by HBV are key regulators of cell proliferation and viability. Our results show that studies on HBV-related HCCs allow to identify cellular genes involved in cancer. We therefore propose this approach as a valuable tool for functional cancer genomic studies in humans.