An alpha-subunit-secreting cell line derived from a mouse thyrotrope tumor.

The anterior pituitary contains multiple distinct endocrine cell types that secrete individual hormones. To derive a pure cell culture population in which to study the regulation of the alpha-subunit of TSH free of other hormones and cell types, we have developed a clonal continuous cell line from the transplantable thyrotrope tumor MGH101A. This cell line expresses alpha-subunit mRNA, secretes alpha-subunit protein, and has maintained a stable phenotype for over 3 yr in culture. However, as is the case for the transplantable tumor from which they are derived, these cells do not express the beta-subunit of TSH or respond to TRH or thyroid hormone. We have used this cell line to investigate regulation of the alpha-subunit mRNA by the second messengers, cAMP and phorbol esters, and by glucocorticoids. Phorbol esters increase alpha-subunit mRNA levels significantly (3.5-fold), as does cAMP (1.8-fold). In contrast, glucocorticoids decrease mRNA levels from cAMP-induced or basal levels (2-fold). These cells should prove valuable for study of alpha-subunit gene expression in an isolated renewable clonal cell culture system.