title: Carnosic acid induces proteasomal degradation of Cyclin B1, RB and SOX2 along with cell growth arrest and apoptosis in GBM cells.
abstract: BACKGROUND
  Carnosic acid (CA) is a diterpenoid found in Rosmarinus officinalis L. and Salvia officinalis L. as well as in many other Lamiaceae. This compound is reported to have antioxidant and antimicrobial properties. In addition, a number of reports showed that CA has a cytotoxic activity toward several cancer cell lines.
  
  
  OBJECTIVE
  The aim of this study was to establish whether CA has any specific antiproliferative effect toward human glioblastoma (GBM) cells and to analyze the molecular mechanisms involved.
  
  
  METHODS
  We evaluated cell survival by MTT assay, apoptosis and DNA content by flow cytometry, protein expression and phosphorylation by immunoblot analyses.
  
  
  RESULTS
  Our results showed that CA inhibited cell survival on both normal astrocytes and GBM cells. In GBM cells, in particular, CA caused an early G2 block, a reduction in the percentage of cells expressing Ki67, an enhanced expression of p21(WAF) and induced apoptosis. Furthermore, we showed that CA promoted proteasomal degradation of several substrate proteins, including Cyclin B1, retinoblastoma (RB), SOX2, and glial fibrillary acid protein (GFAP), whereas MYC levels were not modified. In addition, CA dramatically reduced the activity of CDKs.
  
  
  CONCLUSIONS
  In conclusion, our findings strongly suggest that CA promotes a profound deregulation of cell cycle control and reduces the survival of GBM cells via proteasome-mediated degradation of Cyclin B1, RB and SOX2.
authors.affiliation: DIMES, Dipartimento di Medicina Sperimentale, Anatomia Umana, Università di Genova, Via de Toni 14, 16132 Genova, Italy.
authors.forename: Katia
authors.initials: K
authors.lastname: Cortese
authors.affiliation: IRCCS AOU - San Martino - IST, Largo Rosanna Benzi, 10, 16132 Genova, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Daga
authors.affiliation: IRCCS AOU - San Martino - IST, Largo Rosanna Benzi, 10, 16132 Genova, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Monticone
authors.affiliation: DIMES, Dipartimento di Medicina Sperimentale, Anatomia Umana, Università di Genova, Via de Toni 14, 16132 Genova, Italy; IRCCS AOU - San Martino - IST, Largo Rosanna Benzi, 10, 16132 Genova, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Tavella
authors.affiliation: IRCCS AOU - San Martino - IST, Largo Rosanna Benzi, 10, 16132 Genova, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Stefanelli
authors.affiliation: IRCCS AOU - San Martino - IST, Largo Rosanna Benzi, 10, 16132 Genova, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Aiello
authors.affiliation: Dip. Farmacia, Università di Genova, Via Brigata Salerno 13, 16147 Genova, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Bisio
authors.affiliation: DIMES, Dipartimento di Medicina Sperimentale, Anatomia Umana, Università di Genova, Via de Toni 14, 16132 Genova, Italy.
authors.forename: Grazia
authors.initials: G
authors.lastname: Bellese
authors.affiliation: IRCCS AOU - San Martino - IST, Largo Rosanna Benzi, 10, 16132 Genova, Italy. Electronic address: patrizio.castagnola@hsanmartino.it.
authors.forename: Patrizio
authors.initials: P
authors.lastname: Castagnola
mesh_terms: D045784:Abietanes / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001253:Astrocytes / Q000187:drug effects; D001932:Brain Neoplasms / Q000473:pathology*; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D056744:Cyclin B1 / Q000187:drug effects* / Q000235:genetics; D004273:DNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D016195:G2 Phase / Q000187:drug effects; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects* / Q000235:genetics; D016160:Retinoblastoma Protein / Q000187:drug effects* / Q000235:genetics; D055748:SOXB1 Transcription Factors / Q000187:drug effects* / Q000235:genetics
chemical_list: D045784:Abietanes; D000972:Antineoplastic Agents, Phytogenic; C534699:CCNB1 protein, human; D056744:Cyclin B1; D004273:DNA, Neoplasm; D016160:Retinoblastoma Protein; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; D046988:Proteasome Endopeptidase Complex; C018381:salvin
keywords: Carnosic acid; Cyclin B1; Glioma; Proteasome; Retinoblastoma; SOX2