Induction of p21~(Waf1/Cip1) by Garcinol via Downregulation of p38-IVIAPK Signaling in p53-lndependent HI299 Lung Cancer

摘要

Garcinol, a polyisoprenylated benzophenone, from Garcinia indica fruit rind has possessed anti-inflammatory, antioxidant, antiproliferation, and anticancer activities. However, the anticancer mechanisms of garcinol in lung cancer were still unclear. Therefore, we examine the effects of garcinol on antiproliferation in human lung cancer cells. Treatments with garcinol for 24 h exhibited morphological changes and inhibited the proliferation of H460 (p53-wild type) and H1299 (p53-null) cells in dose-and time-dependent manners. Furthermore, a significant Gl cell cycle arrest was observed in a dose-dependent treatment after HI299 cells were exposed in garcinol, whereas garcinol induced apoptosis rather than cell cycle arrest in H460 cells. Moreover, cyclin-dependent kinase 2 (CDK2), cyclin-dependent kinase 4 (CDK4), Cyclin Dl, and cyclin D3 were decreased, although cyclin E and cyclin-dependent kinase 6 (CDK6) were increased in garcinol-treated HI299 cells. Meanwhile, the protein levels of CDK inhibitors p21~(Waf1/Cip1) and p27~(kip1) also exhibited upregulation after garcinol treatments. The enhanced protein-associated level between p21~(Waf1/Cip1) and CDK4/2 rather than p27~(kip1) and CDK4/2 was demonstrated in garcinol-treated cells. Additionally, knock-down p21~(Waf1/Cip1) by specific siRNA competently prevented garcinol-induced Gl arrest. Besides, garcinol also inhibited ERK and p38-MAPK activations in time-dependent mode. The pretreatment with p38-MAPK inhibitor but not ERK inhibitor raised garcinol-induced Gl population cells. Co-treatment with p38-MAPK inhibitor and garcinol synergistically elevated cyclin E, p21~(Waf1/Cip1) and p27~(kip1)l expressions. Meanwhile, overexpression dominant negative p38-MAPK also enhanced garcinol-induced p21~(Waf1/Cip1) expression in H1299 cells. Accordingly, our data suggested that garcinol induced Gl cell cycle arrest and apoptosis in lung cancer cells under different p53 statuses. The p53-independent Gl cell cycle arrest induced by garcinol might be through upregulation of p21~(Waf1/Cip1) triggered from p38-MAPK signaling inactivation. Kgarcinol;; lung cancer;; pS3;; Gl arres;; p21~(Waf1/Cip1);; p38-MAPK