INHIBITORY EFFECT OF SIALOADENECTOMY ON HEPATOCELLULAR TUMORIGENESIS IN MALE-MICE INDUCED BY 3'-METHYL-4-DIMETHYLAMINOAZOBENZENE

Male C57BL/6xDS-F-1 mice that had been treated with 3'-methyl-4-dimeth ylaminoazobenzene (3'-Me-DAB) neonatally were subjected to sialoadenec tomy (removal of the submandibular salivary glands) 60 days after birt h. The development of adenomatous nodules and carcinomas in the livers of these mice was compared with the livers of males without sialoaden ectomy. The incidence of adenomatous nodules in sialoadenectomized mal es at 6, 8, 10, and 12 months was significantly lower than that in sha m-operated animals. Carcinomas were found in the livers of both sham-o perated and sialoadenectomized males that were 10 and 12 months old an d were less frequent in sialoadenectomized males although the differen ce was significant only at the age of 12 months. Sialoadenectomy decre ased the serum concentration of epidermal growth factor (EGF) by about 40%. The present results indicate that sialoadenectomy inhibits the d evelopment of hepatocellular tumours induced by 3'-Me-DAB in male mice , an effect which may be caused by decrease in the serum level of EGF.