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Opposite effect of stable transfection of bioactive transforming growth factor‐β1 (TGFβ1) versus exogenous TGFβ1 treatment on expression of 92‐kDa type iv collagenase in mouse skin squamous cell carcinoma CH72 cells
Author(s) -
Rundhaug Joyce E.,
Park Jeanie,
Pavone Amy,
Opdenakker Ghislain,
Fischer Susan M.
Publication year - 1997
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/(sici)1098-2744(199707)19:2<122::aid-mc7>3.0.co;2-h
Subject(s) - biology , transfection , transforming growth factor , collagenase , cell culture , microbiology and biotechnology , messenger rna , carcinogenesis , endocrinology , gene , enzyme , biochemistry , genetics
We have previously shown that transforming growth factor‐β1 ( TGFβ1 ) mRNA is consistently overexpressed in squamous cell carcinomas relative to normal mouse skin. Here we show that 92‐kDa type IV collagenase (matrix metalloproteinase) ( MMP‐9 ) mRNA was likewise progressively overexpressed during mouse skin carcinogenesis. To determine if overexpression of MMP‐9 and TGFβ1 are linked, we stably transfected a bioactive TGFβ1 into a mouse skin squamous cell carcinoma cell line (CH72), which resulted in about twofold to threefold higher levels of secreted active TGFβ1. Active TGFβ1 –transfected cells grew only slightly, but not significantly, more slowly in vitro and in vivo than vector‐only transfectants. Two clones overexpressing active TGFβ1 secreted much reduced levels of MMP‐9 activity, as determined by zymogram analyses. However, treatment of these clones with 40 pM exogenous TGFβ1 for 48 h enhanced secretion of MMP‐9 activity. Constitutive mRNA expression of MMP‐9 was reduced twofold to 70‐fold in five untreated active TGFβ1 –transfected clones relative to the other transfectants. In contrast, treatment with 40 pM exogenous TGFβ1 induced MMP‐9 mRNA expression in a time‐dependent fashion, from twofold to fourfold after 4 h to a maximum of 12‐ to 19‐fold after 24–48 h. Induction of MMP‐9 mRNA was dose dependent at TGFβ1 concentrations of 4–400 pM. Thus, stable transfection of bioactive TGFβ1 downregulated whereas exogenous TGFβ1 treatment upregulated MMP‐9 activity and expression. Treatment of transfectants with a neutralizing TGFβ1 antibody slightly downregulated constitutive MMP‐9 mRNA (20–30%) but completely blocked induction by exogenous TGFβ1. Thus, the effect of TGFβ1 transfection was not due to secreted TGFβ1 but may have been a secondary effect. Mol. Carcinog. 19:122–136, 1997. © 1997 Wiley‐Liss, Inc.