Abstract
We investigated the expression of transforming growth factors beta 1 and alpha (TGF-beta 1, TGF-alpha) in hormone-responsive (MPA-R) and unresponsive (MPA-U) tumor lines obtained from medroxyprogesterone acetate (MPA)-induced mammary adenocarcinomas in BALB/c mice. The tumors were transplanted into MPA-treated and untreated mice. TGF-beta 1 gene expression was observed in the MPA-R lines growing in untreated animals, but not in MPA-treated mice. TGF-beta 1 mRNA was not detected in the MPA-U tumor lines growing in either MPA-treated or untreated animals. In MPA-R lines the levels of TGF-beta 1 expression were inversely correlated to growth rate. High-affinity TGF-beta 1 receptors were present in the MPA-R tumors. These results suggest that one of the mechanisms by which MPA exerts its proliferative effect on MPA-R tumor lines is inhibition of the expression of TGF-beta 1. Thus, the lack of expression of TGF-beta 1 in MPA-U tumors may be related to the acquisition of autonomous growth.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenocarcinoma / chemically induced
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Adenocarcinoma / metabolism*
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Animals
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Female
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Gene Expression
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Mammary Neoplasms, Experimental / chemically induced
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Mammary Neoplasms, Experimental / metabolism*
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Medroxyprogesterone Acetate / pharmacology*
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Mice
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Mice, Inbred BALB C
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Neoplasm Transplantation
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Neoplasms, Hormone-Dependent / chemically induced
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Neoplasms, Hormone-Dependent / metabolism*
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RNA, Messenger / analysis
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RNA, Neoplasm / analysis
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Receptors, Estrogen / biosynthesis
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Receptors, Progesterone / biosynthesis
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Receptors, Transforming Growth Factor beta / biosynthesis
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Transforming Growth Factor alpha / biosynthesis
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Transforming Growth Factor alpha / genetics
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Transforming Growth Factor beta / biosynthesis*
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Transforming Growth Factor beta / genetics
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Transforming Growth Factor beta / metabolism
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Tumor Cells, Cultured
Substances
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RNA, Messenger
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RNA, Neoplasm
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Receptors, Estrogen
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Receptors, Progesterone
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Receptors, Transforming Growth Factor beta
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Transforming Growth Factor alpha
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Transforming Growth Factor beta
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Medroxyprogesterone Acetate