In Vitro and in Vivo Atheroprotective Effects of Gossypetin against Endothelial Cell Injury by Induction of Autophagy

Abstract

Oxidized low-density lipoprotein (ox-LDL) contributes to the pathogenesis of atherosclerosis by promoting vascular endothelial cell injury.Gossypetin, a naturally occurring hexahydroxyflavone, has been shown to possess antimutagenic, antioxidant, antimicrobial, and antiatherosclerotic effects. In this study, the atheroprotective role of gossypetin was examined in endothelial cells. The protective effect of gossypetin against ox-LDL-induced injury in human umbilicalvein endothelial cells (HUVECs) was first noted at 0.1−0.5 μM. Gossypetin showed potential in reducing ox-LDL-dependent apoptosis, as demonstrated by morphological and biochemical features, including formation of apoptotic bodies,distribution of hypodiploid phase, and activation of caspase-3. Next, the ox-LDL induced formation of acidic vesicular organelles and the upregulation of autophagyrelated genes (LC3 and Beclin-1) were enhanced by gossypetin. Gossypetin triggered autophagic flux was further confirmed by an increase in the level of LC3-II under pretreatment conditions with an autophagy inhibitor, chloroquine (CQ). In addition, silencing Beclin-1 inhibited both the gossypetin-mediated protective affects and the autophagic process. Molecular data indicated that the autophagic effect of gossypetin might be mediated via the class III PI3K/Beclin-1 and PTEN/class I PI3K/Akt signaling cascades, as demonstrated by the use of a class III PI3K inhibitor, 3-methyladenine (3-MA), and a PTEN inhibitor, SF1670. Finally, gossypetin improved atherosclerotic lesions and endothelial injury in vivo. These data imply that gossypetin upregulates the autophagic pathway, which led to subsequent reduction of ox-LDL-induced atherogenic endothelial cell injury and apoptosis, and provide a new mechanism for the antiatherosclerotic activity of gossypetin.

Anti‐prostate cancer potential of gossypetin via inducing apoptotic and autophagic cell death

“…Our results demonstrated that GTIN treatments induced a significant cell cycle arrest at G0/G1 phase in LNCaP cell, but its apoptosis‐inducing effect was lower than DU145 cells (Figure C and Figure ). This is consistent with previous observation that GTIN possesses only weak cytotoxicity and inhibited the proliferation of human pulmonary epithelial cells, murine macrophage cells, and human umbilical vein endothelial cells (HUVECs) without causing cell death . Collectively, these findings indicate that the inhibitory effect of GTIN on the growth of LNCaP cells may be contributed by the induction of cell cycle arrest, apoptosis or others.…”

“…Furthermore, it is still a matter of debate as to whether natural products, such as resveratrol, not only suppress cancer cells by activating apoptosis but also protect normal cells from oxidative injury via autophagy induction . In agreement with these previous studies, the findings from our study reveal that GTIN at higher dosage range induced not only apoptosis (≥50 μM) but also autphagic cell death (25 μM) in LNCaP cells (Figures ‐), and, on the other hand, lower concentrations (0.1‐0.5 μM) had a protective effect via autophagy induction in HUVECs . The findings, hence, provided evidences supporting a multifunction of GTIN on LNCaP cells and HUVECs between high and low concentrations.…”

“…49,50 In agreement with these previous studies, the findings from our study reveal that GTIN at higher dosage range induced not only apoptosis (≥50 μM) but also autphagic cell death (25 μM) in LNCaP cells (Figures 2-5), and, on the other hand, lower concentrations (0.1-0.5 μM) had a protective effect via autophagy induction in HUVECs. 44 The findings, hence, provided evidences supporting a multifunction of GTIN on LNCaP cells and HUVECs between high and low concentrations. Our results further suggested that the induction of autophagy in PCa cells were likely to be cell type-specific.…”

“…This is consistent with previous observation that GTIN possesses only weak cytotoxicity and inhibited the proliferation of human pulmonary epithelial cells, murine macrophage cells, and human umbilical vein endothelial cells (HUVECs) without causing cell death. [42][43][44] Collectively, these findings indicate that the inhibitory effect of GTIN on the growth of LNCaP cells may be contributed by the induction of cell cycle arrest, apoptosis or others. Supporting our data, it has been previously reported that gossypol, a derivate form of GTIN, induced not only apoptosis but also autophagy in PCa cells.…”

Role of autophagy in advanced atherosclerosis

“…In advanced AS, plaque rupture or erosion may cause acute clinical events. However, in early AS with endothelial dysfunction (33), the repair of VEC injuries may prevent the subsequent development of AS. Furthermore, in advanced AS, apoptotic macrophages may be quickly cleaned-up by macrophages, to prevent the progression of inflammation and plaque necrosis, thereby delaying plaque development (29).…”