title: Muscadine Grape Skin Extract Induces an Unfolded Protein Response-Mediated Autophagy in Prostate Cancer Cells: A TMT-Based Quantitative Proteomic Analysis.
abstract: Muscadine grape skin extract (MSKE) is derived from muscadine grape (Vitis rotundifolia), a common red grape used to produce red wine. Endoplasmic reticulum (ER) stress activates the unfolded protein response (UPR) that serves as a survival mechanism to relieve ER stress and restore ER homeostasis. However, when persistent, ER stress can alter the cytoprotective functions of the UPR to promote autophagy and cell death. Although MSKE has been documented to induce apoptosis, it has not been linked to ER stress/UPR/autophagy. We hypothesized that MSKE may induce a severe ER stress response-mediated autophagy leading to apoptosis. As a model, we treated C4-2 prostate cancer cells with MSKE and performed a quantitative Tandem Mass Tag Isobaric Labeling proteomic analysis. ER stress response, autophagy and apoptosis were analyzed by western blot, acridine orange and TUNEL/Annexin V staining, respectively. Quantitative proteomics analysis indicated that ER stress response proteins, such as GRP78 were greatly elevated following treatment with MSKE. The up-regulation of pro-apoptotic markers PARP, caspase-12, cleaved caspase-3, -7, BAX and down-regulation of anti-apoptotic marker BCL2 was confirmed by Western blot analysis and apoptosis was visualized by increased TUNEL/Annexin V staining upon MSKE treatment. Moreover, increased acridine orange, and LC3B staining was detected in MSKE-treated cells, suggesting an ER stress/autophagy response. Finally, MSKE-mediated autophagy and apoptosis was antagonized by co-treatment with chloroquine, an autophagy inhibitor. Our results indicate that MSKE can elicit an UPR that can eventually lead to apoptosis in prostate cancer cells.
authors.affiliation: Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, United States of America.
authors.forename: Liza J
authors.initials: LJ
authors.lastname: Burton
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Universidad Central del Caribe, Bayamon, PR, 00956, United States of America.
authors.forename: Mariela
authors.initials: M
authors.lastname: Rivera
authors.affiliation: Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, United States of America.
authors.forename: Ohuod
authors.initials: O
authors.lastname: Hawsawi
authors.affiliation: Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, United States of America.
authors.forename: Jin
authors.initials: J
authors.lastname: Zou
authors.affiliation: Department of Medicine, Howard University, Washington, DC, 20060, United States of America.
authors.forename: Tamaro
authors.initials: T
authors.lastname: Hudson
authors.affiliation: Department of Chemistry, Xavier University, New Orleans, LA, 70125, United States of America.
authors.forename: Guangdi
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Xavier University, New Orleans, LA, 70125, United States of America.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Universidad Central del Caribe, Bayamon, PR, 00956, United States of America.
authors.forename: Luis
authors.initials: L
authors.lastname: Cubano
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Universidad Central del Caribe, Bayamon, PR, 00956, United States of America.
authors.forename: Nawal
authors.initials: N
authors.lastname: Boukli
authors.affiliation: Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, United States of America.
authors.forename: Valerie
authors.initials: V
authors.lastname: Odero-Marah
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D053454:Caspase 12 / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002738:Chloroquine / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology; D040901:Proteomics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D015854:Up-Regulation / Q000187:drug effects; D027843:Vitis / Q000737:chemistry* / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D010936:Plant Extracts; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D002738:Chloroquine; D053454:Caspase 12; D053148:Caspase 3