J. Biol. Chem., Vol. 261, Issue 26, 11956-11961, Sep, 1986
Loss of thyroidal inducibility of Na,K-ATPase with neoplastic transformation in tissue culture
DL Guernsey and IS Edelman
Thyroidal induction of the plasma membrane Na,K-ATPase is a characteristic
of mammalian tissues that exhibit a thermogenic response to this hormone.
To facilitate analysis of the pathways mediating this response, we defined
the conditions needed for reproducible thyroidal induction of this enzyme,
as well as mitochondrial cytochrome c oxidase, in established cell lines in
tissue cultures. In confluent monolayers of nontransformed mouse embryo
fibroblasts (C3H/10T1/2), triiodothyronine modulated Na,K-ATPase and
cytochrome c oxidase activities in a concentration- and time-dependent
manner. Similar increases in Na,K-ATPase activity were obtained in other
rodent embryo cells (SWISS/3T3 and NIH/3T3) and in human fibroblasts
(WI-38). In contrast, neoplastic transformation of all of these cell lines
resulted in loss of inducibility of Na,K-ATPase by thyroid hormone,
regardless of the initiating mechanism (i.e. spontaneous, x-ray, chemicals,
viruses).