A mechanistic study of the proapoptotic effect of tolfenamic acid: involvement of NF- B activation

Abstract

Recent studies demonstrate that tolfenamic acid (TA) induces apoptosis and suppresses the development and progression of several types of cancers. However, the underlying mechanisms are complex and remain to be fully elucidated. Nuclear factor-kappaB (NF-κB) plays a critical role in inflammation, cancer development and progression. Although non-steroidal anti-inflammatory drugs modulate NF-κB signaling pathway in different ways, the link between NF-κB and TA-induced apoptosis of colorectal cancer cells has yet to be thoroughly investigated. In this study, we examined the effects of TA on the NF-κB pathway and apoptosis. TA activated NF-κB transcriptional activity and binding affinity of NF-κB to DNA. TA-induced NF-κB activation was mediated by an increased phosphorylation and proteosomal degradation of IκB-α and subsequent p65 nuclear translocation. We also observed that TA stabilized p65 and increased nuclear accumulation via an increase of p65 phosphorylation at Ser276 residue, which was mediated by p38 mitogen-activated protein kinase and extracellular signal-regulated kinase. The knockout of p53 blocked TA-induced transcriptional activation of NF-κB, but not the p65 nuclear accumulation. TA increased transcriptional activity of p53 and the binding affinity of p53 with p65, which are mediated by p38 mitogen-activated protein kinase and extracellular signal-regulated kinase-stimulated Ser276 phosphorylation. TA-induced apoptosis was ameliorated by the knockout of p65 and p53 and the point mutation of p65 at Ser276 residue. We demonstrate a novel molecular mechanism by which TA induced the NF-κB and apoptosis in human colorectal cancer cells.

Reactive oxygen species mediate tolfenamic acid-induced apoptosis in human colorectal cancer cells

“…6). Indeed, we observed that TA activates NF-jB transcriptional activity [45] and ATF3 activation, which is required for TA-induced apoptosis [15]. NF-jB is a key mediator of the cellular stress response and activation of NF-jB can induce apoptosis [46].…”

“…Previously, we reported that TA-stimulated apoptosis is associated with up-regulation of pro-apoptotic proteins, early growth response-1 (EGR-1) and activating transcription factor 3 (ATF3) [14,15]. In terms of NF-jB activation, we also reported that TA increases nuclear p65 translocation through IKK-mediated translocation and p65 accumulation through a novel mechanism involving proteosomal degradation and cooperation of p65 with p53 [45]. Therefore, the present study demonstrates that TA-stimulated ROS generation may play a significant upstream role by targeting various cancer-associated proteins and contribute TAinduced apoptosis in cancer.…”

“…These data indicate that TA-induced ROS generation and subsequent ERK activation may lead to DNA damage. TA activates NF-jB via ROS-dependent pathway ROS-mediated DNA damage and oxidative stress activate NF-jB transcriptional activity [30,31] and we observed that TA increased transcriptional activity of NF-jB and nuclear translocation/accumulation of p65 (RelA) [45]. Therefore, we tested if ROS mediates TA-induced NF-jB activation.…”

Anti-inflammatory and anti-cancer activity of mulberry (Morus alba L.) root bark

“…However, pretreatment of MRBE dose-dependently inhibited LPS-induced p65 nuclear translocation in RAW264.7 cells. There is a growing evidence that NF-κB activation is modulated by ERK1/2 activation [24]. Thus, we evaluated the effects of MRBE on phosphorylation of ERK1/2 in LPS-stimulated RAW264.7 cells using Western blot to further investigate whether inhibition of NF-κB activation by MRBE was associated with modulation of ERK1/2.…”

Induction of Cyclin D1 Proteasomal Degradation by Branch Extracts from Abeliophyllum distichum Nakai in Human Colorectal Cancer Cells

“…We found anticancer therapy (Verma, 2004;Kim et al, 2006). However, some reports suggest that NF-κB activation by aspirin and tolfenamic acid promotes a proapoptotic response in cancer cells (Stark et al, 2001;Jeong et al, 2013). Although tolfenamic acid induces NF-κB activation in human colorectal cancer cell line, HCT116, it has been reported that tolfenamic acid suppresses inflammatory stimuli-mediated NF-κB signaling pathway in HCT116 cells (Shao et al, 2015).…”