Effects of hormones (E2: estradiol, TP: testosterone) and propylthiouracil (PTU) on the growth of transplantable rat thyroid tumor (F2D1) having estrogen receptors were studied. Rat thyroid neoplasms, induced by N-bis (2-hydroxypropyl) nitrosamine, were inoculated subcutaneously from donor to recipient rats, in order to establish 16 transplantable rat thyroid tumor lines. The grafts were used for histological studies and for the assay of estrogen receptor (ER) and androgen receptor (AR). Of these lines, we designated papillary carcinoma, which was positive for ER (N: 12.5fmol/mg protein, Kd: 0.4nM) but negative for AR, as F2D1. For studies on the effects of sex hormones and PTU on the growth of transplantable tumors, the rats which had been inoculated with tumors were divided into the following 8 groups; (1) Intact, (2) PTU, (3) ovariectomy (OV), and (4) OV + E2 for female, and (5) Intact, (6) PTU, (7) castration (CA), and (8) CA + TP for male.
Results: The growth rate of F2D1 in female rats was decreased by OV, but no change was observed in OV + E2 as compared with Intact. CA and CA + TP in male rats did not influence the growth rate. PTU produced a significant increase in the growth rate in both sexes. These results demonstrate that estrogen and PTU act on the growth of ER-positive rat thyroid tumors.