title: Piperine causes G1 phase cell cycle arrest and apoptosis in melanoma cells through checkpoint kinase-1 activation.
abstract: In this study, we determined the cytotoxic effects of piperine, a major constituent of black and long pepper in melanoma cells. Piperine treatment inhibited the growth of SK MEL 28 and B16 F0 cells in a dose and time-dependent manner. The growth inhibitory effects of piperine were mediated by cell cycle arrest of both the cell lines in G1 phase. The G1 arrest by piperine correlated with the down-regulation of cyclin D1 and induction of p21. Furthermore, this growth arrest by piperine treatment was associated with DNA damage as indicated by phosphorylation of H2AX at Ser139, activation of ataxia telangiectasia and rad3-related protein (ATR) and checkpoint kinase 1 (Chk1). Pretreatment with AZD 7762, a Chk1 inhibitor not only abrogated the activation of Chk1 but also piperine mediated G1 arrest. Similarly, transfection of cells with Chk1 siRNA completely protected the cells from G1 arrest induced by piperine. Piperine treatment caused down-regulation of E2F1 and phosphorylation of retinoblastoma protein (Rb). Apoptosis induced by piperine was associated with down-regulation of XIAP, Bid (full length) and cleavage of Caspase-3 and PARP. Furthermore, our results showed that piperine treatment generated ROS in melanoma cells. Blocking ROS by tiron protected the cells from piperine mediated cell cycle arrest and apoptosis. These results suggest that piperine mediated ROS played a critical role in inducing DNA damage and activation of Chk1 leading to G1 cell cycle arrest and apoptosis.
authors.affiliation: Department of Biomedical Sciences and Cancer Biology Center, Texas Tech University Health Sciences Center, Amarillo, Texas, United States of America.
authors.forename: Neel M
authors.initials: NM
authors.lastname: Fofaria
authors.affiliation: Cancer Preventive Material Development Research Center, College of Korean Medicine, Department of Pathology, Kyunghee University, Seoul, South Korea.
authors.forename: Sung-Hoon
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Biomedical Sciences and Cancer Biology Center, Texas Tech University Health Sciences Center, Amarillo, Texas, United States of America; Cancer Preventive Material Development Research Center, College of Korean Medicine, Department of Pathology, Kyunghee University, Seoul, South Korea.
authors.forename: Sanjay K
authors.initials: SK
authors.lastname: Srivastava
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D052117:Benzodioxoles / Q000494:pharmacology*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects*; D000071877:Checkpoint Kinase 1; D004789:Enzyme Activation / Q000187:drug effects; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D006801:Humans; D008545:Melanoma / Q000378:metabolism; D010880:Piperidines / Q000494:pharmacology*; D053284:Polyunsaturated Alkamides / Q000494:pharmacology*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000470:Alkaloids; D052117:Benzodioxoles; D010880:Piperidines; D053284:Polyunsaturated Alkamides; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C008922:piperine