Abstract
In a previous report we have shown that a few substances, especially thiouracil, are incorporated as false precursors into melanin during its synthesis. In the present investigation, we have intensified our studies on the incorporation of thiouracil into melanotic melanomas. Firstly, the distribution and retention of both 14C- and 35S-labelled thiouracil in mice with transplanted melanomas were studied. A high and selective accumulation was found in the melanotic tumours. The concentration in the rest of the body was low, with the exception of the thyroid gland. Secondly, melanoma-bearing mice were given increasing doses of thiouracil, and cultured melanoma cells were exposed to different concentrations of thiouracil, to investigate the relation between dose and uptake in melanomas and melanoma cells, respectively. A relatively linear increase in uptake with dose was found, indicating that the melanin incorporation of thiouracil is non-saturable up to subtoxic levels.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Comis R. L., Carter S. K. Integration of chemotherapy into combined modality therapy of solid tumors. IV. Malignant melanoma. Cancer Treat Rev. 1974 Dec;1(4):285–304. doi: 10.1016/s0305-7372(74)80020-4. [DOI] [PubMed] [Google Scholar]
- Dencker L., Larsson B., Olander K., Ullberg S., Yokota M. False precursors of melanin as selective melanoma seekers. Br J Cancer. 1979 Apr;39(4):449–452. doi: 10.1038/bjc.1979.80. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dencker L., Larsson B., Olander K., Ullberg S., Yokota M. Incorporation of thiouracil and some related compounds into growing melanin. Acta Pharmacol Toxicol (Copenh) 1981 Aug;49(2):141–149. doi: 10.1111/j.1600-0773.1981.tb00883.x. [DOI] [PubMed] [Google Scholar]
- Hornsey S. The relationship between total dose, number of fractions and fractions size in the response of malignant melanoma in patients. Br J Radiol. 1978 Nov;51(611):905–909. doi: 10.1259/0007-1285-51-611-905. [DOI] [PubMed] [Google Scholar]
- POTTS A. M. THE REACTION OF UVEAL PIGMENT IN VITRO WITH POLYCYCLIC COMPOUNDS. Invest Ophthalmol. 1964 Aug;3:405–416. [PubMed] [Google Scholar]
- Whittaker J. R. Biosynthesis of a thouracil pheomelanin in embryonic pigment cells exposed to thouracil. J Biol Chem. 1971 Oct 25;246(20):6217–6226. [PubMed] [Google Scholar]