Apoptosis induction by E2F-1 via adenoviral-mediated gene transfer results in growth suppression of head and neck squamous cell carcinoma cell lines.
E2F-1, a transcription factor by discovery, is thought to play a crucial role in regulating G1/S cell cycle progression. Its activity is modulated by complex formation with the retinoblastoma protein and related proteins. Overexpression of E2F-1 has been shown to induce apoptosis in quiescent fibroblasts. We constructed a recombinant E2F-1 adenovirus to test whether an overexpression of E2F-1 in head and neck squamous cell carcinoma cell lines would also induce apoptosis. Two cell lines, Tu-138 and Tu-167, were chosen for use in this study. Both cell lines harbor p53 mutations but express different levels of the retinoblastoma protein. Upon E2F-1 adenovirus infection, both cell lines expressed elevated levels of E2F-1 protein and then activated a pRb-chloramphenicol acetyltransferase reporter construct containing an E2F-1 binding motif. In vitro growth assay demonstrated that growth suppression by the E2F-1 protein was effective on both cell lines. Results from DNA fragmentation and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling analyses indicated apoptosis induction in cells infected with AdCMV-E2F-1. Moreover, ex vivo experiments in nude mice showed total suppression of tumor growth at sites that received cells infected AdCMV-E2F-1. An in vivo analysis of apoptosis using in situ end-labeling further demonstrated the induction of apoptosis by AdCMV-E2F-1 in tumor-bearing animals. These data indicate that overexpression of E2F-1 via an adenoviral vector suppresses in vitro and in vivo growth of head and neck squamous carcinoma cell lines through induction of apoptosis.
Liu
T J
TJ
Department of Head and Neck Surgery, University of Texas M.D. Anderson Cancer Center, Houston 77303, USA. tjlui@notes.mdacc.tmc.edu
Wang
M
M
Breau
R L
RL
Henderson
Y
Y
El-Naggar
A K
AK
Steck
K D
KD
Sicard
M W
MW
Clayman
G L
GL
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000628:therapy*; D002352:Carrier Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000187:drug effects; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D053938:DNA Fragmentation; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D006258:Head and Neck Neoplasms / Q000628:therapy*; D006801:Humans; D020287:In Situ Nick-End Labeling; D051379:Mice; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000473:pathology; D056465:Retinoblastoma-Binding Protein 1; D013997:Time Factors; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000235:genetics / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
C533431:Arid4a protein, mouse; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C493754:E2f1 protein, mouse; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D015500:Chloramphenicol O-Acetyltransferase