Background: 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), a disinfection by-product in chlorinated drinking water, induces follicular tumors in thyroid glands in Wistar rats. The mechanisms of the MX-induced thyroid gland tumorigenesis are not known.
Materials and methods: The expressions of p53 (primary antibody CM5) and p21 Ki-ras (primary antibody F234) proteins were evaluated by immunohistochemisty in MX-induced tumors in Wistar rats. p53 expression was studied in 3 follicular adenomas, 29 follicular carcinomas and two C-cell carcinomas of thyroid glands. p21 Ki-ras expression was studied in 13 follicular carcinomas and one C-cell carcinoma.
Results: A weak expression of p53 protein (1-5% of tumor cells) observed in six follicular carcinomas (21%) and one C-cell carcinoma was not considered to be p53-positive. No expression of p21 Ki-ras was observed in any of the samples.
Conclusion: These data indicate that p53 and Ki-ras proteins are not overexpressed in the MX-induced thyroid tumors in rats.