Apoptosis, necrosis and hypoxia inducible factor-1 in human head and neck squamous cell carcinoma cultures.
The objective of this study was to examine the mode of cell death and the hypoxia inducible factor-1 (HIF-1) expression of human head and neck squamous cell carcinoma (HNSCC) exposed to hypoxia in vitro. Apoptosis and necrosis rates were examined using flow cytometry. The findings suggest that HNSCC cells show a considerable heterogeneity in cell size and in response to hypoxia. A small-cell population showed a high spontaneous apoptosis and necrosis rate which was in-sensitive to hypoxia. A large-cell population responded to hypoxia by increase of apoptosis rate in parallel to recruitment of HIF-1. Hypoxia led to increased HIF-1alpha protein levels in nuclear extract using ELISA-binding activity. In all cells, accumulation of HIF-1 in the nuclei during hypoxia and a rapid degradation of HIF-1 in the post-hypoxic period were observed immunocytochemically. The HIF-1alpha mRNA level showed an expression of 10-40 pg/microg total RNA and remained unchanged in one cell line, while slightly decreasing in the other. Remarkably, no increased luciferase activity response was found on the reporter gene level using pGL3 reporter gene with three erythropoietin hypoxia responsive elements, either by hypoxia or by application of lactacystin, desferrioxamine or CoCl2. These findings suggest that, in HNSCC cells, hypoxia induces HIF-1alpha to stabilize and accumulate in the cell nuclei but have a cell-specific transcriptional complex.
Gross
Johann
J
Department of Otorhinolaryngology, Charité Hospital, Humboldt University, Berlin, Germany. johann.gross@charite.de
Fuchs
Julia
J
Machulik
Astrid
A
Jahnke
Volker
V
Kietzmann
Thomas
T
Bockmühl
Ulrike
U
D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D017209:Apoptosis; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D048430:Cell Shape; D003035:Cobalt / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D003676:Deferoxamine / Q000494:pharmacology; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006258:Head and Neck Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007150:Immunohistochemistry; D009336:Necrosis; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C067713:lactacystin; D003035:Cobalt; C018021:cobaltous chloride; D003676:Deferoxamine; D000111:Acetylcysteine