Heterogeneous Effects of Growth Factors and Serum on TSH and Foskolin Stimulated Camp Levels in Continuous Cell Strains Derived from Feline Toxic Adenomatous Goiters

Kintzer P.P., Ferguson D.C., Hoenig M., et al.

Annales d’endocrinologie, 1991. 52(1): p.87.


Hyperthyroidism is now the most common endocrine disease of the cat and, based on pathologic, immunologic and xenoptransplantation studies, appears similar to toxic nodular goiter.  We have reported (Gerber et al, Proc Am Thyroid Assoc, 1989) on the proliferative response to growth factors of these cell lines.  Insulin and IGF-1 stimulated growth in PETCAT-1 and PETCAT-2 cell lines but not in normal cells; EGF and serum stimulated all cell types.  In this study, PETCAT-1 and PETCAT-2 cells were grown in 24-well plates in 6H media for 7 days, in 4H for 6 days and then in 4H +/- growth factor (50 ng/ml EGF, 5 ng/ml bFGF, 50 ng/ml IGF-1, 10% calf serum, 10ug/ml insulin or serum/insulin) for 3 days.  Basal samples were collected and cells incubated for 30 and 60 min hypotonic Hanks media (with 0.5 mM IBMX) alone or with 10 mU/ml TSH, 50 mU/ml TSH or 0.1 mM forskolin.  Camp, measured by RIA, is reported as pmol/ug DNA.  Changes, analyzed by ANOVA, are given as % of control.

Cyclic AMP generation by PETCAT 1 in 4H was stimulated by 10 mU TSH (2.39 pmol/ug DNA/30 min; 5.66 pmol/ug DNA/60min), 50 mU TSH (3.80 and 9.71) and forskolin (61.48 and 124.77).  Insulin lowered basal cAMP levels (58%; P<0.05) and tended to decrease the response to TSH and forskolin.  Serum enhanced (P<0.05) responses for 10 mU TSH at 30 and 60 min (383%; 117%), 50mU TSH at 30 min (324%) and forskolin at 30 min (179%).  Serum reversed the inhibitory effect of insulin and, in fact, significantly increased responses to TSH and forskolin.  Generation of camp in PETCAT-2 in 4H was: 10 mU TSH (2.14 pmol/ug DNA/30 min and 5.18 pmol/ug DNA/60 min), 50 mU TSH (2.85 and 6.60) and forskolin (85.82 and 113.14).  Serum enhances (p<0.05) responses for 10 mU TSH at 30 min (471%) and 50 mU TSH at 30 and 60 min (334%: 143%) but not forskolin, implicating alteration of receptor or G protein action in this strain.  EGF, bFGF or IGF-1 failed to alter responses in either cell line.  In summary, serum potentiates the cAMP response to TSH in PETCAT 1 and 2, to forskolin in PETCAT 1 and overcomes the inhibitory action of insulin in PETCAT 1.  Insulin exhibits an inhibitory effect on both basal and stimulated cAMP levels in PETCAT 1.  EGF, bFGF and IGF-1, although growth promotants, fail to alter the stimulatory effect of TSH or forskolin.  These variable responses may reflect heterogeneity of the original lesions.  These cell lines are unique and valuable tools for study of the cellular changes underlying goitrogenesis.