title: The cooperative induction of hypoxia-inducible factor-1 alpha and STAT3 during hypoxia induced an impairment of tumor susceptibility to CTL-mediated cell lysis.
abstract: Hypoxia is an essential component of tumor microenvironment. In this study, we investigated the influence of hypoxia (1% PO(2)) on CTL-mediated tumor cell lysis. We demonstrate that exposure of target tumor cells to hypoxia has an inhibitory effect on the CTL clone (Heu171)-induced autologous target cell lysis. Such inhibition correlates with hypoxia-inducible factor-1alpha (HIF-1alpha) induction but is not associated with an alteration of CTL reactivity as revealed by granzyme B polarization or morphological change. Western blot analysis indicates that although hypoxia had no effect on p53 accumulation, it induced the phosphorylation of STAT3 in tumor cells by a mechanism at least in part involving vascular endothelial growth factor secretion. We additionally show that a simultaneous nuclear translocation of HIF-1alpha and phospho-STAT3 was observed. Interestingly, gene silencing of STAT3 by small interfering RNA resulted in HIF-1alpha inhibition and a significant restoration of target cell susceptibility to CTL-induced killing under hypoxic conditions by a mechanism involving at least in part down-regulation of AKT phosphorylation. Moreover, knockdown of HIF-1alpha resulted in the restoration of target cell lysis under hypoxic conditions. This was further supported by DNA microarray analysis where STAT3 inhibition resulted in a partly reversal of the hypoxia-induced gene expression profile. The present study demonstrates that the concomitant hypoxic induction of phospho-STAT3 and HIF-1alpha are functionally linked to the alteration of non-small cell lung carcinoma target susceptibility to CTL-mediated killing. Considering the eminent functions of STAT3 and HIF-1alpha in the tumor microenvironment, their targeting may represent novel strategies for immunotherapeutic intervention.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, Unité 753, Villejuif, France.
authors.forename: Muhammad Zaeem
authors.initials: MZ
authors.lastname: Noman
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Buart
authors.forename: Jos
authors.initials: J
authors.lastname: Van Pelt
authors.forename: Catherine
authors.initials: C
authors.lastname: Richon
authors.forename: Meriem
authors.initials: M
authors.lastname: Hasmim
authors.forename: Nathalie
authors.initials: N
authors.lastname: Leleu
authors.forename: Wictoria Maria
authors.initials: WM
authors.lastname: Suchorska
authors.forename: Abdelali
authors.initials: A
authors.lastname: Jalil
authors.forename: Yann
authors.initials: Y
authors.lastname: Lecluse
authors.forename: Faten
authors.initials: F
authors.lastname: El Hage
authors.forename: Massimo
authors.initials: M
authors.lastname: Giuliani
authors.forename: Christophe
authors.initials: C
authors.lastname: Pichon
authors.forename: Bruno
authors.initials: B
authors.lastname: Azzarone
authors.forename: Nathalie
authors.initials: N
authors.lastname: Mazure
authors.forename: Pedro
authors.initials: P
authors.lastname: Romero
authors.forename: Fathia
authors.initials: F
authors.lastname: Mami-Chouaib
authors.forename: Salem
authors.initials: S
authors.lastname: Chouaib
mesh_terms: D045744:Cell Line, Tumor; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic; D015972:Gene Expression Regulation, Neoplastic / Q000276:immunology; D006801:Humans; D000860:Hypoxia / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis* / Q000502:physiology; D007113:Immunity, Innate; D008175:Lung Neoplasms / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism / Q000473:pathology
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human