Kaempferol induces ATM/p53-mediated death receptor and mitochondrial apoptosis in human umbilical vein endothelial cells

Abstract

Abstract. Kaempferol is a member of the flavonoid compounds found in vegetables and fruits. It is shown to exhibit biological impact and anticancer activity, but no report exists on the angiogenic effect of kaempferol and induction of cell apoptosis in vitro. In this study, we investigated the role of kaempferol on anti-angiogenic property and the apoptotic mechanism of human umbilical vein endothelial cells (HUVECs). Our results demonstrated that kaempferol decreased HUVEC viability in a time-and concentration-dependent manner. Kaempferol also induced morphological changes and sub-G1 phase cell population (apoptotic cells). Kaempferol triggered apoptosis of HUVECs as detecting by DNA fragmentation, comet assay and immunofluorescent staining for activated caspase-3. The caspase signals, including caspase-8, -9 and -3, were time-dependently activated in HUVECs after kaempferol exposure. Furthermore, pre-treatment with a specific inhibitor of caspase-8 (Z-IETD-FMK) significantly reduced the activity of caspase-8, -9 and -3, indicating that extrinsic pathway is a major signaling pathway in kaempferoltreated HUVECs. Importantly, kaempferol promoted reactive oxygen species (ROS) evaluated using flow cytometric assay in HUVECs. We further investigated the upstream extrinsic pathway and showed that kaempferol stimulated death receptor signals [Fas/CD95, death receptor 4 (DR4) and DR5] through increasing the levels of phosphorylated p53 and phosphorylated ATM pathways in HUVECs, which can be individually confirmed by N-acetylcysteine (NAC), ATM specific inhibitor (caffeine) and p53 siRNA. Based on these results, kaempferol-induced HUVEC apoptosis was involved in an ROS-mediated p53/ATM/death receptor signaling. Kaempferol might possess therapeutic effects on cancer treatment in anti-vascular targeting.

Kaempferol inhibits angiogenic ability by targeting VEGF receptor-2 and downregulating the PI3K/AKT, MEK and ERK pathways in VEGF-stimulated human umbilical vein endothelial cells

“…In addition, we also demonstrated that kaempferol suppressed U-2 OS cell metastasis through suppression of the ERK/p38/JNK and AP-1 signaling pathways (28). In an anti-angiogenic study, our earlier research indicated that kaempferol induced ROS-mediated p53/ATM-dependent apoptosis in human umbilical vein endothelial cells (HUVECs) (29). However, there is no available information regarding the possible major target and anti-angiogenic mechanism of kaempferol in endothelial cells.…”

Chemo‐preventive and therapeutic effect of the dietary flavonoid kaempferol: A comprehensive review

“…In human umbilical vein endothelial cells (HUVECs), Lee et al () showed that kaempferol induces sub‐G1 phase cell population, activates the caspase signals such as caspase‐3, ‐8, and ‐9 and triggers apoptosis in a dose‐dependent manner. Additionally, it stimulates death receptor signals (death receptor 4 [DR4], Fas/CD95, and DR5) by enhancing the expressions of phosphorylated ataxia telangiectasia mutated (ATM) and phosphorylated p53 pathways (Lee et al, ).…”

“…In human umbilical vein endothelial cells (HUVECs), Lee et al () showed that kaempferol induces sub‐G1 phase cell population, activates the caspase signals such as caspase‐3, ‐8, and ‐9 and triggers apoptosis in a dose‐dependent manner. Additionally, it stimulates death receptor signals (death receptor 4 [DR4], Fas/CD95, and DR5) by enhancing the expressions of phosphorylated ataxia telangiectasia mutated (ATM) and phosphorylated p53 pathways (Lee et al, ). In a similar fashion, research by Liao and colleagues revealed that kaempferol displays anticancer activity against different human cancer cell lines, such as the human stomach carcinoma (SGC‐7901), human breast carcinoma (MCF‐7), human lung carcinoma (A549), and human cervical carcinoma (Liao et al, ).…”

The Role of p53-Mediated Signaling in the Therapeutic Response of Colorectal Cancer to 9F, a Spermine-Modified Naphthalene Diimide Derivative

“…In response to stress, p53 acts as a transcriptional factor that regulates the expression of downstream target genes involved in the cell cycle, apoptosis, DNA damage and senescence [27,28]. A correlation has been identified between p53 and the death receptor [29,30], which suggests a significant role of p53 in death receptor-mediated cell death. Metastasis is the main cause of cancer death, and the epithelial-to-mesenchymal transition (EMT) is a crucial process for metastasis [31,32].…”