title: P2X7 receptor as predictor gene for glioma radiosensitivity and median survival.
abstract: Glioblastoma multiforme (GBM) is considered the most lethal intracranial tumor and the median survival time is approximately 14 months. Although some glioma cells present radioresistance, radiotherapy has been the mainstay of therapy for patients with malignant glioma. The activation of P2X7 receptor (P2X7R) is responsible for ATP-induced death in various cell types. In this study, we analyzed the importance of ATP-P2X7R pathway in the radiotherapy response P2X7R silenced cell lines, in vivo and human tumor samples. Both glioma cell lines used in this study present a functional P2X7R and the P2X7R silencing reduced P2X7R pore activity by ethidium bromide uptake. Gamma radiation (2Gy) treatment reduced cell number in a P2X7R-dependent way, since both P2X7R antagonist and P2X7R silencing blocked the cell cytotoxicity caused by irradiation after 24h. The activation of P2X7R is time-dependent, as EtBr uptake significantly increased after 24h of irradiation. The radiotherapy plus ATP incubation significantly increased annexin V incorporation, compared with radiotherapy alone, suggesting that ATP acts synergistically with radiotherapy. Of note, GL261 P2X7R silenced-bearing mice failed in respond to radiotherapy (8Gy) and GL261 WT-bearing mice, that constitutively express P2X7R, presented a significant reduction in tumor volume after radiotherapy, showing in vivo that functional P2X7R expression is essential for an efficient radiotherapy response in gliomas. We also showed that a high P2X7R expression is a good prognostic factor for glioma radiosensitivity and survival probability in humans. Our data revealed the relevance of P2X7R expression in glioma cells to a successful radiotherapy response, and shed new light on this receptor as a useful predictor of the sensitivity of cancer patients to radiotherapy and median survival.
authors.affiliation: PUCRS, Programa de Pós-Graduação em Biologia Celular e Molecular, Laboratório de Farmacologia Aplicada, Av. Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil. Electronic address: marinapgehring@gmail.com.
authors.forename: Marina P
authors.initials: MP
authors.lastname: Gehring
authors.affiliation: Laboratório de Sinalização e Plasticidade Celular, UFRGS, Av. Bento Gonçalves, 9500, 91501-970 Porto Alegre, RS, Brazil. Electronic address: franciele.kipper@yahoo.com.br.
authors.forename: Franciele
authors.initials: F
authors.lastname: Kipper
authors.affiliation: PUCRS, Programa de Pós-Graduação em Biologia Celular e Molecular, Laboratório de Farmacologia Aplicada, Av. Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil. Electronic address: natifn@gmail.com.
authors.forename: Natália F
authors.initials: NF
authors.lastname: Nicoletti
authors.affiliation: PUCRS, Programa de Pós-Graduação em Biologia Celular e Molecular, Laboratório de Farmacologia Aplicada, Av. Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil. Electronic address: nati.sperotto@hotmail.com.
authors.forename: Nathalia D
authors.initials: ND
authors.lastname: Sperotto
authors.affiliation: PUCRS, Programa de Pós-Graduação em Biologia Celular e Molecular, Laboratório de Farmacologia Aplicada, Av. Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil. Electronic address: rafaelzaninn@gmail.com.
authors.forename: Rafael
authors.initials: R
authors.lastname: Zanin
authors.affiliation: Laboratório de Sinalização e Plasticidade Celular, UFRGS, Av. Bento Gonçalves, 9500, 91501-970 Porto Alegre, RS, Brazil. Electronic address: alessandratamajusuku@unipampa.edu.br.
authors.forename: Alessandra S K
authors.initials: AS
authors.lastname: Tamajusuku
authors.affiliation: Cancer Research Laboratory, University Hospital Research Center (CPE-HCPA), Porto Alegre, RS, Brazil. Electronic address: dgazzanaf@unisinos.br.
authors.forename: Debora G
authors.initials: DG
authors.lastname: Flores
authors.affiliation: Departamento de Patologia, HCPA, UFRGS, Rua Ramiro Barcelos, 2350, 90420-010 Porto Alegre, RS, Brazil. Electronic address: lmeurer@terra.com.br.
authors.forename: Luise
authors.initials: L
authors.lastname: Meurer
authors.affiliation: Laboratory of Neuropharmacology and Neural Tumor Biology, Department of Pharmacology, Institute for Basic Health Sciences, UFRGS, Porto Alegre, RS, Brazil; Cancer Research Laboratory, University Hospital Research Center (CPE-HCPA), UFRGS, Porto Alegre, RS, Brazil; National Institute for Translational Medicine, Rua Sarmento Leite, 500, Sala 202, 90050-170 Porto Alegre, RS, Brazil. Electronic address: rroesler@terra.com.br.
authors.forename: Rafael
authors.initials: R
authors.lastname: Roesler
authors.affiliation: Serviço de Radioterapia, Hospital São Lucas da PUCRS, Av. Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil. Electronic address: aroldoradioterapia@terra.com.br.
authors.forename: Aroldo B
authors.initials: AB
authors.lastname: Filho
authors.affiliation: Laboratório de Sinalização e Plasticidade Celular, UFRGS, Av. Bento Gonçalves, 9500, 91501-970 Porto Alegre, RS, Brazil. Electronic address: gulenz@gmail.com.
authors.forename: Guido
authors.initials: G
authors.lastname: Lenz
authors.affiliation: PUCRS, Instituto de Toxicologia e Farmacologia e Faculdade de Odontologia, Av. Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil. Electronic address: maria.campos@pucrs.br.
authors.forename: Maria M
authors.initials: MM
authors.lastname: Campos
authors.affiliation: PUCRS, Programa de Pós-Graduação em Biologia Celular e Molecular, Laboratório de Farmacologia Aplicada, Av. Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil. Electronic address: fernanda.morrone@pucrs.br.
authors.forename: Fernanda B
authors.initials: FB
authors.lastname: Morrone
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D001932:Brain Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D016923:Cell Death; D045744:Cell Line, Tumor; D004996:Ethidium / Q000378:metabolism; D005720:Gamma Rays; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D005909:Glioblastoma / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011836:Radiation Tolerance / Q000235:genetics*; D058486:Receptors, Purinergic P2X7 / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D016019:Survival Analysis
chemical_list: D017304:Annexin A5; C546468:P2RX7 protein, human; D034741:RNA, Small Interfering; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D004996:Ethidium
keywords: ATP; Glioma; Median survival; P2X7 receptor; Radiotherapy