Lack of suppression of tumor cell phenotype by overexpression of TIMP-3 in mouse JB6 tumor cells identification of a transfectant with increased tumorigenicity and invasiveness.
BACKGROUND
We have recently cloned mouse tissue inhibitor of metalloproteinases-3 (mTIMP-3) by the differential display technique and found that mTIMP-3 was expressed in preneoplastic but not in neoplastic mouse JB6 epidermal cells (Sun et at. Cancer Res. 54:11139, 1994). This down regulation of the gene is attributable at least in part to alteration in gene methylation (Sun et al., J. Biol. Chem., 270:19312, 1995).


METHODS
To examine the potential role of TIMP-3 in two JB6 tumor cell model, we overexpressed mouse TIMP-3 in two JB6 tumor cell lines lacking endogenous mTIMP-3 expression. Stable transfectants from each line were selected and assayed for possible changes in tumor cell phenotype.


RESULTS
Our results showed overexpression of mTIMP-3 in these two tumor lines did not change their ability to grow in soft agar, an assay for anchorage-independent growth, nor in nude mice, an in vivo tumorigenicity assay, nor to penetrate matrigel, an assay for invasiveness We, however, isolated a clone which is highly malignant was demonstrated by a) very short latent period for tumor formation; b) very fast tumor growth; and c) highly invasive in the matrigel assay.


CONCLUSIONS
We conclude from this study that although TIMP-3 is not expressed in mouse JB6 tumor cells, overexpression by DNA transfection did not reverse tumor cell phenotype, suggesting a complex role for TIMP-3 in tumorigenesis. The highly malignant transfectant isolated by this study can be used as a tool for the cloning of dominant oncogenes as well as tumor suppressor genes.
Sun
Y
Y
Laboratory of Viral Carcinogenesis National Cancer Institute, Frederick Cancer Research & Development Center, MD 21702, USA.
Kim
H
H
Parker
M
M
Stetler-Stevenson
W G
WG
Colburn
N H
NH
D000818:Animals; D002455:Cell Division / Q000502:physiology; D018450:Disease Progression; D051379:Mice; D009361:Neoplasm Invasiveness; D010641:Phenotype; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D019717:Tissue Inhibitor of Metalloproteinase-3; D014162:Transfection; D014407:Tumor Cells, Cultured
D011506:Proteins; D019717:Tissue Inhibitor of Metalloproteinase-3