Transfection of wild-type TP53 induces differentiation in human gingival carcinoma cells.
We investigated the effects of transfection of wild-type TP53 on the growth properties of a human gingival carcinoma cell line, KOSC-3, in which the TP53 gene is mutated at codon 248 and overexpressed. The wild-type TP53 expression plasmid, pCDM8-p53/neo and the control plasmid, pCDM8/neo, were each stably transfected into KOSC-3 cells by using the calcium phosphate method. The number of G418-resistant colonies from wild-type TP53-transfected cells was approximately half that from plasmid controls. Exogenous wild-type TP53 transcripts were identified in four of the 20 G418-resistant clones analysed by reverse transcription PCR. Although the growth rates of the wild-type TP53+ clones did not drastically change during log phase, their saturation density was significantly reduced. The wild-type TP53+ cells were morphologically flat and enlarged when cultured in vitro, and were less able to form colonies in soft agar. In nude mice, the wild-type TP53+ clones formed subcutaneous tumours with conspicuous keratinisation and notable cell death that was not manifested in the parental and plasmid control cells. These findings indicate that the wild-type TP53 gene, even when it coexists with a mutated form, may function as a growth suppressor and differentiation inducer under restricted conditions in gingival squamous cell carcinoma.
Takahashi
R
R
Department of Tumour Biology and Pathology, Graduate School of Medicine, Kyoto University, Japan.
Inagaki
T
T
Matsuwari
S
S
Fujioka
M
M
Maeda
S
S
Ijuhin
N
N
Haga
H
H
Koh
T
T
Shimada
K
K
Saya
H
H
D000818:Animals; D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D018014:Gene Transfer Techniques; D016158:Genes, p53 / Q000235:genetics*; D005887:Gingival Neoplasms / Q000235:genetics* / Q000473:pathology; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger