Biochemical and Biophysical Research Communications
Quercetin restrains TGF-β1-induced epithelial–mesenchymal transition by inhibiting Twist1 and regulating E-cadherin expression
Introduction
The epithelial–mesenchymal transition (EMT) is regarded as a crucial process during tumor initiation and progression, and this process is also recognized as a key step toward cancer metastasis [1]. Loss of E-cadherin is considered a hallmark event of EMT that initiates a series of signal transduction pathways and major cytoskeletal reorganization processes [2]. In response, a cohort of EMT-inducing transcription factors, including Twist, Snail, Slug, and ZEB1, has been reported to activate EMT programs in epithelial cells, and their elevated expression has been well documented in invasive tumors [[3], [4], [5]].
Transforming growth factor-beta 1 (TGF-β1), a potent regulator of EMT, regulates a wide range of cellular functions, including tumor initiation, progression, and extracellular matrix remodeling [6]. Upon TGF-β1 treatment, epithelial cells switch from a cuboidal to an elongated spindle shape and demonstrate enhanced expression of Snail1 and Twist1 and subsequently decreased expression of E-cadherin [7]. As a transcription factor, Twist1 plays a vital role in inducing metastasis in tumor cells through the EMT process [8]. Indeed, ectopic expression of Twist1 decreases E-cadherin, occludin and claudin-7 expression and increases Vimentin and N-cadherin expression [3], although its role in the occurrence of TGF-β1-induced EMT has not been fully elucidated.
Quercetin (3,3′,4′,5,7-pentahydroxyflavone), a member of the polyphenolic flavonoid family, is universally distributed across edible plant species and is one of the most potent antioxidants of plant origin [9]. Quercetin is also the most abundant dietary flavonoid in fruit and vegetables [10]. Numerous studies have indicated that quercetin exhibits a range of biological properties, including antioxidant, anti-inflammatory, antiproliferative, and anticancer activities [[11], [12], [13]]. However, little information exists concerning the role of quercetin in tumorigenesis and tumor progression in TGF-β1-activated CRC cells.
In this study, we investigated novel effects of quercetin on TGF-β1-induced EMT in CRC cells and elucidated the underlying downstream signaling mechanism. Our results show that quercetin inhibits E-cadherin expression by decreasing Twist1 expression, leading to the suppression of TGF-β1-induced EMT and migration in CRC.
Section snippets
Reagents
Quercetin, dimethyl sulfoxide (DMSO), propidium iodide (PI), fetal bovine serum (FBS) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) were purchased from Sigma-Aldrich (St. Louis, MO). Purity of quercetin (>98%) was confirmed by high-performance liquid chromatography (HPLC). Stock solutions (200 mM) were prepared in DMSO. Triton X-100 and EDTA were obtained from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Recombinant human TGF-β1 (AF-100-21C) was purchased
TGF-β1 triggers EMT in SW480 cells
To assess whether TGF-β1 affects EMT markers in epithelial cells, SW480 cells were treated with TGF-β1 at various concentrations for various durations to induce an EMT-like process. We found that SW480 cells cultured with TGF-β1 displayed an elongated fibroblast-like morphology with a scattered distribution, whereas cells cultured without TGF-β1 presented a cobblestone-like morphology with tight cell-cell contact in culture (Fig. 1A). Consistent with this observation, Western blot analyses of
Discussion
Quercetin is a naturally occurring chemopreventive agent whose biological activities include anticancer, antioxidant, anti-inflammatory, anti-angiogenic, growth-suppressing, pro-apoptotic, and anti-aging properties [10]. As a cancer-preventing agent, quercetin can also decrease cellular migration, which is a prerequisite for cellular invasion and an often fatal tumorigenic property [14]. Although some reports have indicated an effect of quercetin on tumor metastasis [15,16], its role in
Competing interests
The authors declare no competing financial interests.
Acknowledgments
This research was supported by the Program of National Natural Science Foundation of China (NO.81560407), The Key Project on Social Development by Department of Science and Technology of Guizhou Province (No. 2015SY3046), Natural Science Foundation of Jiangsu Province (BK20160174), the Joint Foundation of Guizhou Province (No. 2015LH7483 and 2015LH7505).
References (21)
- et al.
Epigenetic control of epithelial-to-mesenchymal transition and cancer metastasis
Exp. Cell Res.
(2013) - et al.
Twist, a master regulator of morphogenesis, plays an essential role in tumor metastasis
Cell
(2004) - et al.
Slug and Sox9 cooperatively determine the mammary stem cell state
Cell
(2012) - et al.
Twist1-induced invadopodia formation promotes tumor metastasis
Canc. Cell
(2011) - et al.
Daily quercetin supplementation dose-dependently increases plasma quercetin concentrations in healthy humans
J. Nutr.
(2008) - et al.
The flavonoid quercetin in disease prevention and therapy: facts and fancies
Biochem. Pharmacol.
(2012) - et al.
Antioxidant and anti-inflammatory effects of quercetin in functional and morphological alterations in streptozotocin-induced diabetic rats
Res. Vet. Sci.
(2013) - et al.
Alterations in the extracellular catabolism of nucleotides are involved in the antiproliferative effect of quercetin in human bladder cancer T24 cells
Urol. Oncol.
(2013) - et al.
Quercetin, a potent inhibitor against beta-catenin/Tcf signaling in SW480 colon cancer cells
Biochem. Biophys. Res. Commun.
(2005) - et al.
Quercetin exerts anti-melanoma activities and inhibits STAT3 signaling
Biochem. Pharmacol.
(2014)
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These authors contributed equally to this work.