Histopathological and Biochemical Analyses of Transplantable Renal Adenocarcinoma in Rats Induced by JV-Ethyl-N-hydroxyethylnitrosamine1

Transplantable renal adenocarcinoma can be readily induced in Wistar strain male rats by initiation with A/-ethyl-W-hydroxyethylnitrosamine followed by promotion with ß-cyclodextrin. The transplantability rates of the tumors by s.c. inoculation in new born rats were 33 and 50%, respectively, for tumors of the first and second passages, and 100% for both third and fourth passages. The transplantability rates were affected by route of inoculation; rates of 50 and 100% were observed for s.c. and i.p. inoculations, respectively. The growth rate of tumors induced by i.p. inoculation was 3-fold higher than that induced by s.c. injection. Macroscopically, most of the tumors grew in the s.c. tissue of inoculation sites. However, invasive growth of tumors in spleen, liver, stomach, peritoneum, and intestine were seen in 50% of the animals inoculated i.p.; metastatic cancers to lung were seen in 16%. Histologically, the tumors were well-differen tiated adenocarcinomas composed of uniform cells resembling kidney tubular cells and appeared to be derived from normal kidney tissues. A 5-fold decrease in 7-glutamyl transferase activ ity in tumor tissues was found as compared with that of nontumorous kidney tissues. Electrophoretic analysis of cellular pro teins in polyacrylamide gels revealed that tumor tissues exhibited five new polypeptides with molecular weights of 81,000,64,000, 59,000, 50,000, and 36,000 which were either lacking or undetectable in the nontumourous area and control kidney. In addi tion, protein banding patterns of transplantable renal tumor ap peared to be more heterogeneous than those of primary kidney tumor.