Treatment with siRNA and antisense oligonucleotides targeted to HIF-1alpha induced apoptosis in human tongue squamous cell carcinomas.
Overexpression of hypoxia inducible factor-1alpha (HIF-1alpha) in cancers has been correlated to a more aggressive tumor phenotype. We investigated the effect of HIF-1alpha knockout on the in vitro survival and death of human tongue squamous cell carcinomas (SCC-4 and SCC-9). Under normoxic condition, a basal level of HIF-1alpha protein was constitutively expressed in SCC-9 cells, albeit an undetectable level of HIF-1alpha messages. Exposure to hypoxia induced only a transient increase in mRNA transcript but a prolonged elevation of HIF-1alpha protein and its immediate downstream target gene product, VEGF. Under normoxic or hypoxic conditions, treatment of SCC-9 cells with AS-HIF-1alpha ODN suppressed both constitutive and hypoxia-induced HIF-1alpha expression at both mRNA and protein levels. Knockout of HIF-1alpha gene expression via either AS-HIF-1alpha ODN or siRNA (siRNAHIF-1alpha) treatment resulted in inhibition of cell proliferation and induced apoptosis in SCC-4 and SCC-9 cells. We also demonstrated that exposure of SCC-9 cells to hypoxia led to a time-dependent increase in the expression of bcl-2 and IAP-2, but not p53. The attenuated levels of bcl-2 and IAP-2, and the enhanced activity of caspase-3 after treatment with AS-HIF-1alpha ODN may contribute partly to the effects of HIF-1alpha blockade on SCC-9 cell death. Collectively, our data suggest that a constitutive or hypoxia-induced expression of HIF-1alpha in SCC-9 and SCC-4 cells is sufficient to confer target genes expression essential for tumor proliferation and survival. As a result, interfering with HIF-1alpha pathways by antisense or siRNA strategy may provide a therapeutic target for human tongue squamous cell carcinomas.
Zhang
Qunzhou
Q
Department of Oral & Maxillofacial Surgery, Charles R. Drew University of Medicine and Science, Los Angeles, CA 90059, USA.
Zhang
Zuo-Feng
ZF
Rao
Jian Y
JY
Sato
J Denry
JD
Brown
Jimmy
J
Messadi
Diana V
DV
Le
Anh D
AD
D017209:Apoptosis / Q000187:drug effects*; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D015687:Cell Hypoxia; D002470:Cell Survival; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016376:Oligonucleotides, Antisense / Q000627:therapeutic use*; D010641:Phenotype; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000627:therapeutic use*; D014062:Tongue Neoplasms / Q000473:pathology*; D014157:Transcription Factors / Q000235:genetics* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D014157:Transcription Factors