title: Enhancing effect of thyroxine on tumor growth and metastases in syngeneic mouse tumor systems.
abstract: We studied the effect of thyroxine treatment on tumor growth and metastases resulting from tumor implants on the hind feet of mice in two syngeneic systems. In control, untreated A/Jax mice, tumor Sarcoma 1 at Day 14 after implantation had average tumor weight of 582 +/- 60 (S.D.) mg and showed an incidence of 57% metastases to regional popliteal nodes and 5% metastases to thymus. In contrast, the thyroxine-treated group (40 microgram/mouse s.c., 5 times/week for 1 month) had an average tumor weight of 808 +/- 56 mg (p less than 0.001), and metastases to popliteal nodes and thymus were 90 and 35%, respectively. In another syngeneic tumor system, Lewis fibrosarcoma was implanted in C57BL/6J mice, and the tumor weight and metastatic index (derived from the number and size of the pulmonary tumor foci) were determined at Day 28. Again, the synthetic L-thyroxine treated group showed a significant enhancement tumor growth and metastatic index. The mean tumor weight in the treated group was 385 +/- 26 mg (control, 694 +/- 25 mg; p less than 0.005) and metastatic index was 84 +/- 29 (control, 30 +/- 25; p less than 0.001). Induced hypothyroidism (treatment with 131I, 100 microCi/mouse i.p.) showed the reverse effect on both tumor systems. These results suggest that both tumor systems are dependent on thyroid hormones for their growth and spread.
mesh_terms: D000818:Animals; D001551:Benz(a)Anthracenes; D005260:Female; D006980:Hyperthyroidism / Q000139:chemically induced; D007037:Hypothyroidism / Q000139:chemically induced; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D009362:Neoplasm Metastasis / Q000503:physiopathology; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000139:chemically induced / Q000503:physiopathology*; D009376:Neoplasms, Hormone-Dependent; D013961:Thyroid Gland / Q000503:physiopathology; D013974:Thyroxine / Q000494:pharmacology* / Q000502:physiology; D014185:Transplantation, Isogeneic
chemical_list: D001551:Benz(a)Anthracenes; D013974:Thyroxine