RESUMO
Multidrug resistance (MDR) is the main challenge in the treatment of chronic myeloid leukemia (CML), and P-glycoprotein (P-gp) overexpression is an important mechanism involved in this resistance process. However, some compounds can selectively affect MDR cells, inducing collateral sensitivity (CS), which may be dependent on P-gp. The aim of this study was to investigate the effect of piperine, a phytochemical from black pepper, on CS induction in CML MDR cells, and the mechanisms involved. The results indicate that piperine induced CS, being more cytotoxic to K562-derived MDR cells (Lucena-1 and FEPS) than to K562, the parental CML cell. CS was confirmed by analysis of cell metabolic activity and viability, cell morphology and apoptosis. P-gp was partially required for CS induction. To investigate a P-gp independent mechanism, we analyzed the possibility that poly (ADP-ribose) polymerase-1 (PARP-1) could be involved in piperine cytotoxic effects. It was previously shown that only MDR FEPS cells present a high level of 24 kDa fragment of PARP-1, which could protect these cells against cell death. In the present study, piperine was able to decrease the 24 kDa fragment of PARP-1 in MDR FEPS cells. We conclude that piperine targets selectively MDR cells, inducing CS, through a mechanism that might be dependent or not on P-gp.
Assuntos
Alcaloides/farmacologia , Apoptose , Benzodioxóis/farmacologia , Inibidores das Enzimas do Citocromo P-450/farmacologia , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Piperidinas/farmacologia , Alcamidas Poli-Insaturadas/farmacologia , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Sobrevivência Celular , Humanos , Células K562 , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismoRESUMO
Resveratrol is a promising chemopreventive agent that mediates many cellular targets involved in cancer signaling pathways. p53 has been suggested to play a role in the anticancer properties of resveratrol. We investigated resveratrol-induced cytotoxicity in H1299 cells, which are non-small lung cancer cells that have a partial deletion of the gene that encodes the p53 protein. The results for H1299 cells were compared with those for three cell lines that constitutively express wild-type p53: breast cancer MCF-7, adenocarcinomic alveolar basal epithelia A549 and non-small lung cancer H460. Cell viability assays revealed that resveratrol reduced the viability of all four of these cell lines in a dose- and time-dependent manner. MCF-7, A549 and H460 cells were more sensitive to resveratrol than were H1299 cells when exposed to the drug for 24 h at concentrations above 100 µM. Resveratrol also increased the p53 protein levels in MCF-7 cells without altering the p53 mRNA levels, suggesting a post-translational modulation of the protein. The resveratrol-induced cytotoxicity in these cells was partially mediated by p53 and involved the activation of caspases 9 and 7 and the cleavage of PARP. In H1299 cells, resveratrol-induced cytotoxicity was less pronounced and (in contrast to MCF-7 cells) cell death was not accompanied by caspase activation. These findings are consistent with the observation that MCF-7 cells were positively labeled by TUNEL following exposure to 100 µM resveratrol whereas H1299 cells under similar conditions were not labeled by TUNEL. The transient transfection of a wild-type p53-GFP gene caused H1299 cells to become more responsive to the pro-apoptotic properties of resveratrol, similarly to findings in the p53-positive MCF-7 cells. Our results suggest a possible therapeutic strategy based on the use of resveratrol for the treatment of tumors that are typically unresponsive to conventional therapies because of the loss of normal p53 function.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/genética , Estilbenos/farmacologia , Proteína Supressora de Tumor p53/genética , Antineoplásicos Fitogênicos/toxicidade , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Relação Dose-Resposta a Droga , Feminino , Humanos , Neoplasias Pulmonares/genética , Células MCF-7 , Masculino , Resveratrol , Estilbenos/toxicidade , Ativação Transcricional/efeitos dos fármacos , Transfecção , Proteína Supressora de Tumor p53/metabolismoRESUMO
Melphalan (MEL) is a chemotherapeutic agent used in breast cancer therapy; however, MEL's side effects limit its clinical applications. In the last 20 years, resveratrol (RSV), a polyphenol found in grape skins, has been proposed to reduce the risk of cancer development. The aim of this study was to investigate whether RSV would be able to enhance the antitumor effects of MEL in MCF-7 and MDA-MB-231 cells. RSV potentiated the cytotoxic effects of MEL in human breast cancer cells. This finding was related to the ability of RSV to sensitize MCF-7 cells to MEL-induced apoptosis. The sensitization by RSV involved the enhancement of p53 levels, the decrease of procaspase 8 and the activation of caspases 7 and 9. Another proposed mechanism for the chemosensitization effect of MCF-7 cells to MEL by RSV was the cell cycle arrest in the S phase. The treatment with RSV or MEL increased the levels of p-Chk2. The increase became pronounced in the combined treatments of the compounds. The expression of cyclin A was decreased by treatment with RSV and by the combination of RSV with MEL. While the levels of cyclin dependent kinase 2 (CDK2) remained unchanged by treatments, its active form (Thr(160) -phosphorylated CDK2) was decreased by treatment with RSV and by the combination of RSV with MEL. The activity of CDK7, kinase that phosphorylates CDK2 at Thr(160), was inhibited by RSV and by the combination of RSV with MEL. These results indicate that RSV could be used as an adjuvant agent during breast cancer therapy with MEL.
Assuntos
Melfalan/farmacologia , Estilbenos/farmacologia , Apoptose/efeitos dos fármacos , Western Blotting , Neoplasias da Mama/metabolismo , Ciclo Celular/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Feminino , Humanos , Imunoprecipitação , ResveratrolRESUMO
Melfalan é um agente quimioterápico usado na terapia de câncer de mama. Noentanto, este composto produz efeitos colaterais que limitam suas aplicaçõesclínicas. A combinação de fitoquímicos quimiopreventivos com quimioterápicos tem sido utilizada para sensibilizar células de câncer à quimioterapia. Essa estratégia pode minimizar os efeitos colaterais provocados pelo tratamento. Entre os quimiosensibilizadores potenciais estão os compostos bioativos como o resveratrol (RSV). O objetivo deste trabalho foi investigar os efeitos antitumorais do RSV em associação com melfalan nas células de câncer de mama MCF-7 e MDA-MB-231. Tanto RSV quanto o melfalan reduziram a viabilidade das células MCF-7 e MDA-MB-231. O RSV apresentou um menor efeito citotóxico nas células PBMC do que nas células de câncer de mama. Além disso, o RSV potencializou o efeito citotóxico do melfalan em células de câncer de mama. A sequência dos tratamentos influenciou no efeito antitumoral, uma vez que o tratamento com RSV seguido do melfalan provocou uma maior redução na viabilidade celular do que no tratamento commelfalan seguido do resveratrol. O RSV potencializou a apoptose induzida pelomelfalan. Este efeito pode estar relacionado com o aumento dos níveis de p53, diminuição de procaspase 8 e ativação das caspases 7 e 9. Baseada na análise de citometria de fluxo, 50 M de RSV foi capaz de promover um acúmulo de células na fase S, assim como a sua associação com melfalan, sugerindo um bloqueio nesta fase do ciclo celular. Para testar o papel do ciclo celular na citotoxicidade do melfalan, as células foram bloqueadas nas fases G1, S ou G2/M usando inibidores específicos do ciclo celular e tratadas com melfalan. Estas combinações de drogas também potencializaram o efeito do melfalan em diminuir a viabilidade das célulasMCF-7. Estes resultados sugerem que o bloqueio do ciclo celular induzido pelo RSV pode ser um dos mecanismos desta molécula em sensibilizar as células MCF-7...
Melphalan is a chemotherapeutic agent used in breast cancer therapy; however,MELs side effects limit its clinical applications. The combination of cancerchemopreventive phytochemicals with chemotherapeutic agents has been shown to sensitize cancer cells to chemotherapy. This strategy can minimize the side effects of the treatment. Among the potential chemosensitizers are bioactive compounds such as resveratrol (RSV). The aim of this study was to investigate the antitumor effects of the RSV in combination with melphalan in MCF-7 and MDA-MB-231 breast cancercells. Both RSV and melphalan reduced the viability of MCF-7 and MDA-MB-231cells. RSV showed a lower cytotoxic effect in PBMC cells than in the breast cancer cells. In addition, RSV increased the cytotoxic effect of melphalan in breast cancer cells. The sequence of the treatments affected the anti-tumor effect, since the treatment with RSV followed by melphalan promoted a greater reduction in cell viability than in the treatment with melphalan followed by RSV. RSV increased the melphalan-induced apoptosis. This effect may be related to the enhancement of p53levels, the decrease of procaspase 8 and the activation of caspases 7 and 9. Basedon the flow cytometric analysis, 50 M of RSV was able to promote an accumulation of cells in S phase, as well as their combination with melphalan, suggesting cell cycle arrest in this phase. To test the role of cell cycle progression in increasing melphalans cytotoxicity, cells were arrested in the G1, S, or G2/M phase using the specific cell cycle inhibitors and treated oncomitantly with melphalan. Thesecombinations of drugs also potentiated the ability of melphalan to decrease theviability of MCF-7 cells. These findings suggest that RSV-induced cell cycle arrest in S phase could be one of the mechanisms of RSV to sensitize MCF-7 cells for treatment with melphalan...