Transplantable Calcitonin-Secreting Medullary Carcinomas of the Thyroid in the WAG/Rij Rat

Abstract

Bioassay of medullary thyroid carcinomas occurring spontaneously in older WAG/Rij rats revealed high levels of calcitonin activity in the tumor tissue. Of 10 such spontaneous carcinomas transplanted toyoung WAG/Rij recipients, 7 grew. Several transplantation lines are being maintained. The tumors usually grew slowly and progressively. The hosts died 7–11 months after receiving the transplant, often from an adenoma of the pituitary. Calcitonin activity has been demonstrated both in the tumor transplant and in the serum of the tumor-bearing rats. In a preliminary experiment, calcitonin secretion by tumor tissue in vitro was stimulated by addition of pentagastrin.