RESUMO
The ATP-binding cassette sub-family G member 2 (ABCG2) is implicated as a member of multidrug resistant proteins in tumors, mediating efflux of a wide spectrum of anticancer drugs. Pro-inflammatory cytokines, which are present within the micro-environment of tumors and inflammation, are able to modulate the expressions and activities of different drug transporters. This study was aimed to evaluate the short-term (72-h treatment) effects of interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) on the expression and function of ABCG2 in cervix carcinoma and gastric cancer cells. Effects of pro-inflammatory cytokines on mRNA, protein expression, and function of ABCG2 were studied using real time RT-PCR and flow cytometry methods, respectively. HeLa cells treated with IL-1ß, IL-6, or TNF-α showed decrements in ABCG2 mRNA levels without any changes in protein expression and function of ABCG2. IL-6 and TNF-α had no effects on mRNA, protein expression, and function of ABCG2 in EPG85-257 cells. Although IL-1ß did not alter ABCG2 at mRNA or protein levels in EPG85-257 cells, it augmented function of ABCG2 in these cells. Mitoxantrone accumulation was also amplified in IL-1ß-, IL-6- or TNF-α-treated HeLa cells and in IL-1ß-treated EPG85-257 cells. In conclusion, pro-inflammatory cytokines were able to modulate the expression of ABCG2 at transcriptional and post-transcriptional levels in human cervix and gastric cancer cells.
Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Mediadores da Inflamação/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias Gástricas/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Neoplasias do Colo do Útero/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Antineoplásicos/metabolismo , Resistencia a Medicamentos Antineoplásicos , Feminino , Citometria de Fluxo , Regulação Neoplásica da Expressão Gênica , Células HeLa , Humanos , Mitoxantrona/metabolismo , Proteínas de Neoplasias/genética , RNA Mensageiro/metabolismo , RNA Neoplásico/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Neoplasias Gástricas/genética , Neoplasias Gástricas/imunologia , Fatores de Tempo , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/imunologiaRESUMO
The protein kinase AKT is involved in several signaling pathways that are important for tumor development and progression, suggesting that AKT might be an interesting target for a molecular tumor therapy. In this study, we investigated the AKT expression in ovarian carcinomas and the role of the AKT isoforms to ovarian cancer cell proliferation. We observed an increased AKT expression in 58% of the primary ovarian carcinomas as compared to normal ovaries by immunohistochemistry. AKT expression was significantly associated with positive lymph node status (P=0.002) and advanced FIGO stage (P=0.009). In western blot analysis, total AKT was expressed in all ovarian cancer cell lines and HOSE cells, while phosphorylated AKT was only observed in OVCAR-3 and SKOV-3 cells. The isoforms AKT1 and AKT2 were expressed at the mRNA level in all cell lines, while no relevant AKT3 mRNA levels were detected by conventional and quantitative RT-PCR. To determine the effects on cell proliferation, we used the unselective PI3K-inhibitor LY294002 as well as RNA interference to selectively inhibit the AKT isoforms. Treatment with LY294002 and the AKT2 siRNA reduced proliferation of OVCAR-3 cells. Our results show that AKT is expressed in a subpopulation of advanced ovarian carcinomas suggesting a role for this protein in the progression of this entity. Deactivation of AKT, especially AKT2 can result in reduction of cell growth. Accordingly, AKT is an interesting target for therapeutic intervention in ovarian cancer.