Cristacarpin promotes ER stress-mediated ROS generation leading to premature senescence by activation of p21waf-1

Abstract

Stress-induced premature senescence (SIPS) is quite similar to replicative senescence that is committed by cells exposed to various stress conditions viz. ultraviolet radiation (DNA damage), hydrogen peroxide (oxidative stress), chemotherapeutic agents (cytotoxic threat), etc. Here, we report that cristacarpin, a natural product obtained from the stem bark of Erythrina suberosa, promotes endoplasmic reticulum (ER) stress, leading to sub-lethal reactive oxygen species (ROS) generation and which eventually terminates by triggering senescence in pancreatic and breast cancer cells through blocking the cell cycle in the G1 phase. The majority of cristacarpin-treated cells responded to conventional SA-β-gal stains; showed characteristic p21 waf1 upregulation along with enlarged and flattened morphology; and increased volume, granularity, and formation of heterochromatin foci-all of these features are the hallmarks of senescence. Inhibition of ROS generation by N-acetyl-L-cysteine (NAC) significantly reduced the expression of p21 waf1 , confirming that the modulation in p21 waf1 by anti-proliferative cristacarpin was ROS dependent. Further, the elevation in p21 waf1 expression in PANC-1 and MCF-7 cells was consistent with the decrease in the expression of Cdk-2 and cyclinD1. Here, we provide evidence that cristacarpin promotes senescence in a p53-independent manner. Moreover, cristacarpin treatment induced p38MAPK, indicating the ROS-dependent activation of the MAP kinase pathway, and thus abrogates the tumor growth in mouse allograft tumor model.

Dynamic recognition and repair of DNA complex damage

“…High-LET radiation can induce higher ROS levels in vivo and in vitro compared with low-LET radiation (Datta et al, 2012). High levels of ROS are often related to compact heterochromatin (HC; Chakraborty et al, 2016;Tada et al, 2004). HC prevents γH2AX foci expansion and DSB repair, and the latter is relieved by ATM-dependent KAP-1 phosphorylation (Brunton et al, 2011).…”

Erythrina suberosa: Ethnopharmacology, Phytochemistry and Biological Activities

“…Furthermore, a work on cristacarpin, a prenylated pterocarpan found in E. suberosa bark, confirmed that both PANC-1 (human pancreatic cancer cells) and MCF-7 cells were sensitive to this compound. Indeed, cell viability was decreased without toxic effects on non-cancer cell lines, such as HUVEC (human endothelial cells) and BPH-1 cells (human benign prostatic hyperplasia cells) [36]. In addition, the authors showed that cristacarpin, in an in vivo experiment with a 4T1 allograft mouse mammary carcinoma model, could prevent tumor growth by inducing premature senescence through both G1 phase blocking and ROS-dependent activation of p21/waf1.…”

Natural Polyphenols Targeting Senescence: A Novel Prevention and Therapy Strategy for Cancer

“…ROS induced by multiple extracellular and intracellular effects is widely studied as a main cause of oxidative stress. In senescence, a variety of stressors such as endoplasmic reticulum stress and mitochondrial damage can induce the production of ROS, causing downstream DNA damage, increasing expression of molecules such as p53 and p21, and blocking cell cycle [46,75,80]. B-myb expression levels were downregulated in the aortas of aged mouse, and the inhibition of B-myb induced senescence in primary cultured human aortic endothelial cells, which is mediated by ROS production through p53/p21 signal pathway [93].…”

“…An active flavonoid component oroxin A, which is obtained from the traditional Chinese herb Oroxylum indicum (L.) Kurz, increased ER-Tracker Red-positive cell population and upregulated ER stress-related proteins activating transcription factor 4 (ATF4) and binding immunoglobulin protein (GRP78), caused cell cycle arrest at the G2/M phase and induced senescence in human breast cancer cells while p38-specific inhibitor SB203580 blocked ER stress induced senescence [79]. Cristacarpin, a known isoflavonoid isolated from Erythrina suberosa stem bark, enhanced ER stress with increased expressions of GRP-94 and PERK by activation of p38, thereby generating sub-lethal ROS, elevating the expression of p21 waf1 in a p53-independent manner, and reducing the expressions of Cdk-2 and cyclinD1, which in turn caused cellular senescence through G1 phase cell cycle arrest in pancreatic and breast cancer cells [80]. After treatment with flavokawain B, a flavonoid compound, approximately 60% of human glioblastoma multiforme cells became senescent and this result was attributed to ER stress-dependent autophagy, which was regulated by ATF-4/DNA damage inducible transcript 3 (DDIT3)/tribbles pseudokinase 3 (TRIB3)/mTOR signaling pathway [81].…”

“…Penta-1,2,3,4,6-Ogalloyl-β-d-glucose, a phenolic acid compound, triggered autophagy and activated ERN1 and EIF2AK3 arms of UPR signaling pathways to promote senescence both in cancer cells and a xenograft mouse model of human HepG2 liver cancer [82]. Cristacarpin effectively inhibited allograft mouse tumor growth by promoting ER stress-mediated ROS generation to induce premature senescence [80].…”