Administration of N-methyl-N′-nitro-N-nitrosoguanidine, a glndular stomach carcinogen, at the concentration of 100 µg/ml in drinking water for 8 days induced the appearance of a MHC class II-associated invariant chain in the target organ of stomach pyloric mucosa of male Lewis rats. The up-regulation of the MHC class II-associated invariant chain was revealed by fluorescent differential display analysis, reverse transcription-PCR, Northern blot, and histochemical staining. The appearance of MHC class II and MHC class I was also demonstrated by reverse transcription-PCR and Northern blot. The results suggest the involvement of MHC-controlled immune reactions in chemically-induced stomach carcinogenesis.
Supported in part by the Tutikawa Memorial Fund for Study in Mammalian Mutagenicity (to C. F.). Part of this study was published in the proceedings of Recent Advances in Gastroenterological Carcinogenesis I (Monduzzi Editore).