title: 6-C-(E-phenylethenyl)naringenin induces cell growth inhibition and cytoprotective autophagy in colon cancer cells.
abstract: 6-C-(E-phenylethenyl)naringenin (6-CEPN) is a small molecule found in naringenin fortified fried beef. It has been shown to suppress colon cancer cell proliferation, but the underlying mechanisms are not fully understood. Here we demonstrate that 6-CEPN suppresses tumour cell proliferation through cell cycle arrest in G1phase, induces necrotic cell death and autophagy in colon cancer cells. Blockade of autophagy by knockdown of the essential autophagy proteins, Atg7 or beclin-1, resulted in aggravated cell death in response to 6-CEPN treatment. In addition, genome-wide transcriptome expression profiling by RNA-sequencing revealed that 6-CEPN-mediated gene expression pattern was extremely similar to the transcriptome response induced by a RAS inhibitor salirasib (farnesylthiosalicylic acid [FTS; salirasib]). Subsequent molecular biological and biochemical experiments demonstrated that 6-CEPN indeed strongly inhibited RAS activation, leading to the inhibition of the downstream effector pathways c-Raf/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase kinase and phosphoinositide 3-kinase/AKT/mammalian target of rapamycin. More importantly, our computational molecular docking data showed that 6-CEPN could bind to the active site of isoprenylcysteine carboxyl methyltransferase (Icmt), a critical enzyme for the activation of RAS. Icmt activity assay showed that 6-CEPN inhibited its activity significantly. Knockdown of Icmt by siRNA attenuated 6-CEPN-mediated autophagy and cell death. The present study demonstrates that 6-CEPN induces cell growth inhibition and cytoprotective autophagy in colon cancer cells, at least in part, though inhibition of the Icmt/RAS signalling pathways.
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Yueliang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Daming
authors.initials: D
authors.lastname: Fan
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Beibei
authors.initials: B
authors.lastname: Ru
authors.affiliation: College of Engineering, Peking University, Haidian District, Beijing, China.
authors.forename: Ka-Wing
authors.initials: KW
authors.lastname: Cheng
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Shuting
authors.initials: S
authors.lastname: Hu
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Jiangwen
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Edmund T S
authors.initials: ET
authors.lastname: Li
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China. Electronic address: mfwang@hku.hk.
authors.forename: Mingfu
authors.initials: M
authors.lastname: Wang
mesh_terms: D001343:Autophagy / Q000187:drug effects* / Q000235:genetics; D000071193:Autophagy-Related Protein 7 / Q000235:genetics; D000071186:Beclin-1 / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D015179:Colorectal Neoplasms; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005204:Farnesol / Q000031:analogs & derivatives / Q000494:pharmacology; D044950:Flavanones / Q000378:metabolism / Q000494:pharmacology*; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D055785:Gene Knockdown Techniques; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D062105:Molecular Docking Simulation; D009336:Necrosis; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects / Q000378:metabolism; D011496:Protein Methyltransferases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000187:drug effects / Q000378:metabolism; D012459:Salicylates / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000187:drug effects; D018631:ras Proteins / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000071193:Autophagy-Related Protein 7; D000071186:Beclin-1; D004791:Enzyme Inhibitors; D005204:Farnesol; D044950:Flavanones; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D011496:Protein Methyltransferases; D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf; D012459:Salicylates; D058570:TOR Serine-Threonine Kinases; D018631:ras Proteins; C000621686:6-C-(phenylethenyl)naringenin; C491997:BECN1 protein, human; C093323:farnesylthiosalicylic acid; C056501:protein-S-isoprenylcysteine O-methyltransferase; C509349:ATG7 protein, human; C005273:naringenin
keywords: 6-CEPN; Anticancer; Colon cancer; RAS