title: Autophagy and lysosomal related protein expression patterns in human glioblastoma.
abstract: Glioblastoma cells are resistant to apoptotic stimuli with autophagic death prevailing under cytotoxic stress. Autophagy interfering agents may represent a new strategy to test in combination with chemo-radiation. We investigated the patterns of expression of autophagy related proteins (LC3A, LC3B, p62, Beclin 1, ULK1 and ULK2) in a series of patients treated with post-operative radiotherapy. Experiments with glioblastoma cell lines (T98 and U87) were also performed to assess autophagic response under conditions simulating the adverse intratumoral environment. Glioblastomas showed cytoplasmic overexpression of autophagic proteins in a varying extent, so that cases could be grouped into low and high expression groups. 10/23, 5/23, 13/23, 5/23, 8/23 and 9/23 cases examined showed extensive expression of LC3A, LC3B, Beclin 1, Ulk 1, Ulk 2 and p62, respectively. Lysosomal markers Cathepsin D and LAMP2a, as well as the lyososomal biogenesis transcription factor TFEB were frequently overexpressed in glioblastomas (10/23, 11/23, and 10/23 cases, respectively). TFEB was directly linked with PTEN, Cathepsin D, HIF1α, LC3B, Beclin 1 and p62 expression. PTEN was also significantly related with LC3B but not LC3A expression, in both immunohistochemistry and gene expression analysis. Confocal microscopy in T98 and U87 cell lines showed distinct identity of LC3A and LC3B autophagosomes. The previously reported stone-like structure (SLS) pattern of LC3 expression was related with prognosis. SLS were inducible in glioblastoma cell lines under exposure to acidic conditions and 2DG mediated glucose antagonism. The present study provides the basis for autophagic characterization of human glioblastoma for further translational studies and targeted therapy trials.
authors.affiliation: a Department of Pathology ; Democritus University of Thrace/University General Hospital of Alexandroupolis ; Alexandroupolis , Greece.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Giatromanolaki
authors.forename: Efthimios
authors.initials: E
authors.lastname: Sivridis
authors.forename: Achileas
authors.initials: A
authors.lastname: Mitrakas
authors.forename: Dimitra
authors.initials: D
authors.lastname: Kalamida
authors.forename: Christos E
authors.initials: CE
authors.lastname: Zois
authors.forename: Syed
authors.initials: S
authors.lastname: Haider
authors.forename: Charitomeni
authors.initials: C
authors.lastname: Piperidou
authors.forename: Aglaia
authors.initials: A
authors.lastname: Pappa
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Gatter
authors.forename: Adrian L
authors.initials: AL
authors.lastname: Harris
authors.forename: Michael I
authors.initials: MI
authors.lastname: Koukourakis
mesh_terms: D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D001343:Autophagy / Q000235:genetics; D000071189:Autophagy-Related Protein-1 Homolog; D000071186:Beclin-1; D015415:Biomarkers; D001921:Brain / Q000378:metabolism; D045744:Cell Line, Tumor; D003593:Cytoplasm; D015870:Gene Expression; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism; D011379:Prognosis; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D015415:Biomarkers; D047908:Intracellular Signaling Peptides and Proteins; C477012:MAP1LC3A protein, human; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D000071189:Autophagy-Related Protein-1 Homolog; D017346:Protein Serine-Threonine Kinases; C484754:ULK1 protein, human; C541703:Ulk2 protein, human
keywords: 2DG, 2-deoxy-D-glucose; Abbreviations:; Beclin 1, Coiled-Coil, Moesin-Like BCL2 Interacting Protein; Beclin1; LC3, Microtubule-associated protein 1 light chain 3; LC3A; LC3B; SLS, stone-like structures; SQSTM1; ULK; Ulk, Unc-51 Like Autophagy Activating Kinase; autophagy; glioblastoma; p62; p62, sequestosome 1; prognosis