Barrier-promoting efficiency of two bioactive flavonols quercetin and myricetin on rat intestinal epithelial (IEC-6) cellsviasuppressing Rho activation
RSC ADVANCES
Authors: Fan, Jing; Li, Tie-Jing; Zhao, Xin-Huai
Abstract
Polyphenols are beneficial to human health because of their bio-activities. In this study, two flavonols quercetin and myricetin with or without heat treatment at 100 degrees C for 30 min were assessed for their barrier-promoting efficiency in rat intestinal epithelial (IEC-6) cells. The results indicated that the heated and unheated flavonols at dose levels of 2.5-20 mu mol L(-1)had a nontoxic effect on the cells treated for 24 and 48 h but enhanced the values of cell viability larger than 100% (especially at a dose level of 5 mu mol L-1). Moreover, the cells exposed to these flavonols of 5 mu mol L(-1)for 24 and 48 h had improved barrier integrity compared to the control cells without any flavonol treatment, reflected by enhanced transepithelial electrical resistance and anti-bacterial effect but decreased paracellular permeability and bacterial translocation. Moreover, the results from both mRNA and protein expression verified 1.1-3.4 fold up-regulation of zonula occludens-1, occludin, and claudin-1 that are critical to tight junctions and barrier function of cells. Furthermore, the expression of other two proteins RhoA and ROCK in the treated cells was also down-regulated, demonstrating suppressed Rho activation and consequently barrier promotionviathe RhoA/ROCK signaling pathway. Overall quercetin, due to its lower molecular polarity, mostly gave higher barrier-promoting efficiency than myricetin, while the heated flavonols were always less efficient than the unheated counterparts to promote barrier integrity of IEC-6 cells. It is thus highlighted that flavonols can provide barrier-promoting effects on intestinal epithelial cells with a promoting efficiency dependent on flavonol polarity; however, heat treatment especially excessive heat treatment of plant foods might lead to damaged flavonol activity.
Rhophilin-associated tail protein 1 promotes migration and metastasis in triple negative breast cancer via activation of RhoA
FASEB JOURNAL
Authors: Liu, Qinghua; Huang, Xinjian; Li, Qingyuan; He, Lixin; Li, Siqi; Chen, Xiangfu; Ouyang, Ying; Wang, Xi; Lin, Chuyong
Abstract
Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype with high motile and invasive capacity that contributes to metastasis. Understanding the mechanisms for the motility of TNBC might provide novel targetable vulnerabilities of the tumors. Herein, we find that Rhophilin-associated tail protein 1 (ROPN1) is selectively overexpressed in human TNBC cell lines and tissues. Overexpression of ROPN1 promotes, while silencing of ROPN1 inhibits the robust migration, invasion, and in vivo metastasis of TNBC cells. Moreover, we find that ROPN1 activates RhoA signaling via rhophilin-1 (RHPN1), leading to enhanced actin stress fibers formation in TNBC cells. RhoA signaling is demonstrated to be essential for ROPN1-mediated migration and metastasis of TNBC cells. Finally, we find that high levels of ROPN1 are significantly associated distant metastasis and predicted poor prognosis in patients with breast cancer. These findings reveal a novel mechanism for the high motility and metastasis of TNBC cells, suggesting that ROPN1 might be a potential prognostic marker and therapeutic target.