Luteolin, a common dietary flavonoid, has been found to have antitumor properties and therefore poses special interest for the development of preventive and/or therapeutic agent for cancers. E-cadherin, a marker of epithelial cells, mediates cell-cell adhesion. Decreased expression of E-cadherin results in a loss of cell-cell adhesion and an increased cell invasion. Many studies have shown the antiproliferative activities of luteolin on cancer cells. However, the effects of luteolin on invasion of cancer cells remain unclear. In this article, we show that luteolin inhibits invasion of prostate cancer PC3 cells through E-cadherin. We found that Luteolin induced expression of E-cadherin through mdm2. Overexpression of mdm2 or knockdown of E-cadherin could restore invasion of PC3 cells after luteolin treatment. Luteolin inhibits mdm2 through AKT and overexpression of active AKT attenuated luteolin-induced expression of E-cadherin, suggesting that luteolin regulates E-cadherin through AKT/mdm2 pathway. The in vivo experiments showed that luteolin inhibited spontaneous lung metastasis of PC3 cells implanted onto the nude mice. These findings provide a new sight into the mechanisms that luteolin is against cancer cells, and suggest that molecular targeting of E-cadherin by luteolin may be a useful strategy for treatment of invasive prostate cancers.
"It has been shown that the decrease in E-cadherin is associated with poor prognosis in various human tumors (10–13). In addition, E-cadherin overexpression in cultured cells and in vivo tumor models leads to a decrease of invasiveness and metastasis (14). Immunohistochemical studies on PC tissue microarray showed that SNAIL staining is associated with Gleason grade (15) with increasing expression from benign prostatic hyperplasia (BPH) to PC bone metastasis (16). "
[Show abstract][Hide abstract] ABSTRACT: Prostate cancer (PC) is a leading male oncologic malignancy wideworld. During malignant transformation, normal epithelial cells undergo genetic and morphological changes known as epithelial-mesenchymal transition (EMT). Several regulatory genes and specific marker proteins are involved in PC EMT. Recently, syndecans have been associated with malignancy grade and Gleason score in PC. Considering that SNAIL is mainly a gene repressor increased in PC and that syndecan promoters have putative binding sites for this repressor, we propose that SNAIL might regulate syndecan expression during PC EMT. The aim of this study was to analyze immunochemically the expression of SNAIL, syndecans 1 and 2 and other EMT markers in a tissue microarray (TMA) of PC samples and PC cell lines. The TMAs included PC samples of different Gleason grade and benign prostatic hyperplasia (BPH) samples, as non‑malignant controls. PC3 and LNCaP cell lines were used as models of PC representing different tumorigenic capacities. Semi-quantitative immunohistochemistry was performed on TMAs and fluorescence immunocytochemistry and western blot analysis were conducted on cell cultures. Results show that SNAIL exhibits increased expression in high Gleason specimens compared to low histological grade and BPH samples. Accordingly, PC3 cells show higher SNAIL expression levels compared to LNCaP cells. Conversely, syndecan 1, similarly to E-cadherin (a known marker of EMT), shows a decreased expression in high Gleason grades samples and PC3 cells. Interestingly, syndecan 2 shows no changes associated to histological grade. It is concluded that increased SNAIL levels in advanced PC are associated with low expression of syndecan 1. The mechanism by which SNAIL regulates the expression of syndecan 1 remains to be investigated.
International Journal of Oncology 01/2014; 44(3). DOI:10.3892/ijo.2014.2254 · 3.03 Impact Factor
"The pursuit of novel compounds able to block or reverse EMT has become an emerging issue. Luteolin, a well-known flavonoid compound, has been reported to inhibit the migration/invasion and prevent the EMT phenomenon of some malignant cancers such as PC-3 (prostate cancer) and A431 (skin cancer) (Lee et al., 2006; Zhou et al., 2009). Other flavonoid compounds including quercetin, epigallocatechin-3-gallate, apigenin, theaflavin, and baicalein exhibit similar inhibitory effects of migration/invasion and EMT in skin, melanoma, breast, and HCC (hepatocellularcarcinoma) cells (Noh et al., 2010; Sil et al., 2010; Wang et al., 2010). "
[Show abstract][Hide abstract] ABSTRACT: Luteolin is a natural flavonoid that possesses a variety of pharmacological activities, such as anti-inflammatory and anti-cancer abilities. Whether luteolin regulates the transformation ability of Lung cancer cells remains unclear. The current study aims to uncover the effects and underling mechanisms of luteolin in regulation of and Epithelial-mesenchymal transition of lung cancer cells.
The lung adenocarcinoma A549 cells were used in this experiment; the cells were pretreated with luteolin followed by administration with TGF-β1. The expression levels of various cadherin and related upstream regulatory modules were examined, KEY FINDINGS: Pretreatment of luteolin prevented the morphological change and downregulation of E-cadherin of A549 cells induced by TGF-β1. In addition, the activation of PI3K-AKT-IκBa-NF-κB-snail pathway which leading to the decline of E-cadherin induced by TGF-β1 also attenuated under the pretreatment of luteolin.
We provide the mechanisms about how luteolin attenuated the Epithelial-mesenchymal transition of A549 lung cancer cells induced by TGF-β1. This finding will strengthen the anti-cancer effects of flavonoid compounds via the regulation of migration/invasion and EMT ability of various cancer cells.
Life sciences 10/2013; 109(2). DOI:10.1016/j.lfs.2013.10.004 · 2.70 Impact Factor
"Furthermore, as a highly prevalent flavonoid in plants, luteolin exhibits favorable biological activity and potential anti-tumor capacity12 and has also been reported to induce the apoptosis of tumor cells and to inhibit EMT in PC3 cells13. In this study, the reversal of EMT was investigated in B16F10 malignant melanoma cells in both in vitro and in vivo animal experiments. "
[Show abstract][Hide abstract] ABSTRACT: Aim:
To investigate whether luteolin, a highly prevalent flavonoid, reverses the effects of epithelial-mesenchymal transition (EMT) in vitro and in vivo and to determine the mechanisms underlying this reversal.
Murine malignant melanoma B16F10 cells were exposed to 1% O2 for 24 h. Cellular mobility and adhesion were assessed using Boyden chamber transwell assay and cell adhesion assay, respectively. EMT-related proteins, such as E-cadherin and N-cadherin, were examined using Western blotting. Female C57BL/6 mice (6 to 8 weeks old) were injected with B16F10 cells (1×106 cells in 0.2 mL per mouse) via the lateral tail vein. The mice were treated with luteolin (10 or 20 mg/kg, ip) daily for 23 d. On the 23rd day after tumor injection, the mice were sacrificed, and the lungs were collected, and metastatic foci in the lung surfaces were photographed. Tissue sections were analyzed with immunohistochemistry and HE staining.
Hypoxia changed the morphology of B16F10 cells in vitro from the cobblestone-like to mesenchymal-like strips, which was accompanied by increased cellular adhesion and invasion. Luteolin (5−50 μmol/L) suppressed the hypoxia-induced changes in the cells in a dose-dependent manner. Hypoxia significantly decreased the expression of E-cadherin while increased the expression of N-cadherin in the cells (indicating the occurrence of EMT-like transformation), which was reversed by luteolin (5 μmol/L). In B16F10 cells, luteolin up-regulated E-cadherin at least partly via inhibiting the β3 integrin/FAK signal pathway. In experimental metastasis model mice, treatment with luteolin (10 or 20 mg/kg) reduced metastatic colonization in the lungs by 50%. Furthermore, the treatment increased the expression of E-cadherin while reduced the expression of vimentin and β3 integrin in the tumor tissues.
Luteolin inhibits the hypoxia-induced EMT in malignant melanoma cells both in vitro and in vivo via the regulation of β3 integrin, suggesting that luteolin may be applied as a potential anticancer chemopreventative and chemotherapeutic agent.
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