title: Severe hypoxia induces chemo-resistance in clinical cervical tumors through MVP over-expression.
abstract: Oxygen molecule modulates tumour response to radiotherapy. Higher radiation doses are required under hypoxic conditions to induce cell death. Hypoxia may inhibit the non-homologous end-joining DNA repair through down regulating Ku70/80 expression. Hypoxia induces drug resistance in clinical tumours, although the mechanism is not clearly elucidated. Vaults are ribonucleoprotein particles with a hollow barrel-like structure composed of three proteins: major vault protein (MVP), vault poly(ADP-ribose) polymerase, and telomerase associated protein-1 and small untranslated RNA. Over-expression of MVP has been associated with chemotherapy resistance. Also, it has been related to poor outcome in patients treated with radiotherapy alone. The aim of the present study was to assess the relation of Major Vault Protein expression and tumor hypoxia in clinical cervical tumors. MVP, p53 and angiogenesis, together with tumor oxygenation, were determined in forty-three consecutive patients suffering from localized cervix carcinoma. High MVP expression was related to severe hypoxia compared to low MVP expressing tumors (p = 0.022). Tumors over-expressing MVP also showed increased angiogenesis (p = 0.003). Besides it, in this study we show for the first time that severe tumor hypoxia is associated with high MVP expression in clinical cervical tumors. Up-regulation of MVP by hypoxia is of critical relevance as chemotherapy is currently a standard treatment for those patients. From our results it could be suggested that hypoxia not only induces increased genetic instability, oncogenic properties and metastatization, but through the correlation observed with MVP expression, another pathway of chemo and radiation resistance could be developed.
authors: Radiation Oncology Department, Hospital Universitario de Gran Canaria Dr, Negrín, Spain. plara@dcc.ulpgc.es
authors: Pedro C
authors: PC
authors: Lara
authors: Marta
authors: M
authors: Lloret
authors: Bernardino
authors: B
authors: Clavo
authors: Rosa M
authors: RM
authors: Apolinario
authors: Luis Alberto
authors: LA
authors: Henríquez-Hernández
authors: Elisa
authors: E
authors: Bordón
authors: Fausto
authors: F
authors: Fontes
authors: Agustín
authors: A
authors: Rey
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015687:Cell Hypoxia / Q000502:physiology*; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009367:Neoplasm Staging; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D002583:Uterine Cervical Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020394:Vault Ribonucleoprotein Particles / Q000096:biosynthesis* / Q000235:genetics; D000099187:Major Vault Protein
chemical_list: D016159:Tumor Suppressor Protein p53; D020394:Vault Ribonucleoprotein Particles; D000099187:Major Vault Protein