Treatment of 1-methyl-1-nitrosourea-induced mammary tumours with immunostimulatory CpG motifs and 13-cis retinoic acid in female rats: histopathological study.

Histopathological evaluation of the mammary gland tumours of Sprague-Dawley rats induced with 1-methyl-1-nitrosourea (MNU), and treated with either CpG oligodeoxynucleotides (CpG-ODN) and/or 13-cis retinoic acid has been performed in this work. Since, the treatment of animals with CpG-ODN induced a significant decrease of tumour burden and volume in comparison with MNU treated control group (Macejova et al. 2001), it was of high impact to compare histological appearance of tumours in different experimental groups (MNU, CpG-ODN, 13-cis retinoic acid, CpG-ODN plus 13-cis retinoic acid). We have found reduced number of carcinomas with necroses in the CpG motifs treated group when compared to animals treated with MNU only. From the histological point of view the treatment with the CpG-ODN may have some protective effect. Carcinoma patterns proportion in the group treated with CpG-ODN was found to be different in comparison with other experimental groups. Treatment of rats with CpG-ODN had no apparent effect on invasiveness of developed carcinomas.