Sequential protooncogene expression during regeneration in rat stomach.

Cellular protooncogenes such as c-myc and c-Ha-ras may play important roles in the control of regeneration of the stomach. In this study, in situ hybridization histochemistry and immunohistochemistry were used to determine how these protooncogenes and the corresponding oncoproteins are expressed at the cellular level during gastric regeneration after mucosal injuries caused by indomethacin. In addition, cells in the S-phase were immunohistochemically detected by means of 5-bromo-2'-deoxyuridine incorporation. Expression of the c-myc gene was localized to nuclei and reached a maximum at 3 h, and that of the c-Ha-ras gene was localized to cytoplasm with a peak at 6-12 h after treatment on the mucous neck, parietal, chief, and enterochromaffinlike cells around the lesions. The distribution of cells in the S-phase roughly coincided with that of cells in which expression of the protooncogenes was detected. In conclusion, various types of gastric mucosal cells participated in the sequential regulated expression of cellular protooncogenes during regeneration of the rat stomach.