RESUMO
We investigated the effects of isoalantolactone on cell growth inhibition and underlying cell death mechanisms in SKOV3 human ovarian cancer cells. The effects of isoalantolactone on cell proliferation and cell cycle were examined by EdU incorporation assay and DNA content assay. Western blotting was performed to determine the protein expression effects of isoalantolactone on cell cyclerelated proteins, autophagic regulators and PEA15. Autophagic vacuoles were observed by acridine orange staining. PEA15 knockdown by siRNA was used to confirm that PEA15 was involved in isoalantolactoneinduced autophagy of SKOV3 cells. Isoalantolactone inhibited the viability and proliferation of SKOV3 cells in a dose and timedependent fashion. Isoalantolactone induced cell cycle arrest at G2/M phase and decreased the expression of cell cyclerelated proteins cyclin B1 and CDK1 in SKOV3 cells. Accordingly, isoalantolactone also induced SKOV3 cell autophagy via accumulation of autophagic vacuoles in the cytoplasm, increased Beclin1 protein expression, and increased LC3 cleavage. Furthermore, we observed that isoalantolactoneinduced autophagy was through increased PEA15 expression and the phosphorylation of ERK, whereas less change was observed to autophagy on SKOV3 cells through PEA15 knockdown by siRNA. Isoalantolactoneinduced autophagic cell death was further confirmed by pretreatment with the autophagy inhibitor 3methyladenine (3MA). In conclusion, isoalantolactone induced cell cycle arrest and autophagy and inhibited cell proliferation of SKOV3 cells via the upregulated PEA15 expression and the phosphorylation of ERK.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Autofagia/efeitos dos fármacos , Peptídeos e Proteínas de Sinalização Intracelular/biossíntese , Neoplasias Ovarianas/patologia , Fosfoproteínas/biossíntese , Sesquiterpenos/farmacologia , Animais , Proteínas Reguladoras de Apoptose , Western Blotting , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Feminino , Técnicas de Silenciamento de Genes , Humanos , Camundongos Endogâmicos C57BL , RNA Interferente Pequeno , Transfecção , Regulação para Cima , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: Although radiotherapy is one of the mainstream approaches for the treatment of head and neck squamous cell carcinoma (HNSCC), this cancer is always associated with resistance to radiation. In this study, the mechanism of action of isoalantolactone as well as its radiosensitizing effect was investigated in UMSCC-10A cells. METHODS: The radiosensitization of UMSCC-10A cells treated with isoalantolactone was analyzed by colony formation assay. The radiosensitization effects of isoalantolactone on cell proliferation, cell cycle and apoptosis regulation were examined by BrdU incorporation assay, DNA content assay and flow cytometry, respectively. Western blotting was performed to determine the effects of isoalantolactone combined with radiation on the protein expression of Mek, extracellular signal-regulated kinase (Erk1/2) as well as phosphorylated Mek and Erk1/2. Erk1/2 knockdown by siRNA was used to confirm that isoalantolactone specifically inhibited the activation of Erk1/2 signaling pathway in UMSCC-10A cells. RESULTS: Isoalantolactone enhanced the radiosensitivity of UMSCC-10A cells; the sensitivity enhanced ratios (SERs) were 1.44 and 1.63, respectively, for 2.5 and 5 µM. Moreover, isoalantolactone enhanced radiation-induced cell proliferation and apoptosis and cell cycle arrested at G2/M phase. Furthermore, no marked changes were observed in the expression of total Erk1/2 and Mek protein after radiation treatment. However, isoalantolactone was significantly reduced radiation-induced the phosphorylation of Erk1/2, whereas it altered the phosphorylation of Mek to a lesser extent. In addition, the radiosensitivity of UMSCC-10A cells with Erk1/2 knockdown was increased. Isoalantolactone cannot further prevent the proliferation of UMSCC-10A cells with Erk1/2 knockdown which other mechanism regulated cell proliferation. CONCLUSION: Our results suggested that isoalantolactone enhanced radiation-induced apoptosis, cell cycle arrested and reduced the cell proliferation of UMSCC-10A cells via specifically inhibited the phosphorylation of Erk1/2. Thus a low concentration of isoalantolactone may be used to overcome the resistance of UMSCC-10A cells to radiation and may be a promising radiosensitizer in cancer therapy.
Assuntos
Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Tolerância a Radiação/efeitos dos fármacos , Radiossensibilizantes/farmacologia , Sesquiterpenos/farmacologia , Animais , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/metabolismo , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/metabolismo , Divisão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fase G2/efeitos dos fármacos , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/metabolismo , Células Hep G2 , Humanos , Ratos , Transdução de Sinais/efeitos dos fármacosRESUMO
Many studies investigated the relationship between matrix metalloproteinase 2 (MMP-2) overexpression and survival in patients with colorectal cancer (CRC), but yielded inconsistent results. To derive a more precise estimate of the prognostic significance of MMP-2 overexpression, we reviewed published studies and carried out a meta-analysis. Eligible articles were identified for the period up to March 2012 in electronic databases. To evaluate the correlation between MMP-2 overexpression and the prognosis in CRC, pooled hazard ratio (HR) and its 95 % confidence interval (95 % CI) for poorer overall and progression-free survival were appropriately derived from fixed-effects or random-effects models using standard meta-analysis techniques. Thirteen studies with a total of 1,919 CRC patients stratifying overall survival (OS) and/or progression-free survival in CRC patients by MMP-2 expression status were eligible for analysis. Ten studies investigated the OS in a total of 1,612 cases with CRC, and five studies investigated the progression-free survival in a total of 508 patients CRC. The combined HR estimate for OS and progression-free survival was 1.74 (95 % CI, 1.34-2.26) and 1.35 (95 % CI, 1.07-1.80), respectively. Both subgroup analyses and sensitivity analysis further identified the prognostic role of MMP-2 overexpression in patients with CRC. There was no evidence for publication bias. In conclusion, MMP-2 overexpression is associated with poorer overall and progression-free survival in patients with CRC.