The inhibitory effect of genistein on the growth and metastasis of a transplantable rat accessory sex gland carcinoma

Background: A cell line (K1) derived from a carcinogen-induced accessory se x gland carcinoma was used to examine the effects of the soybean extract, g enistein, on tumor growth and metastasis. Methods, Male Lobund-Wistar rats were injected s.c. with 20 million K1 cells; genistein (50 mg/kg BW) or the vehicle was administered s.c. every 12 h for 31 days. Results, Genistein s ignificantly inhibited tumor growth. Compared with controls, fewer genistei n-treated rats developed invasive tumors (11% vs. 44%) or lymph node metast ases (44% vs. 89%), No lung metastases were found in genistein-treated anim als in contrast to controls (0% vs. 44%). Estrogenic side effects were prec ipitated in genistein-treated rats, including decreased accessory sex gland complex weight, increased pituitary weight, decreased testis weight, and d ecreased (BW). Serum testosterone was undetectable and serum prostate-speci fic acid phosphatase activity was 38% lower in genistein-treated rats compa red with controls. Genistein concentrations in the solid tumors (2 nmol/g) were one-third those in blood. Conclusions: These data suggest that geniste in may be a useful chemotherapeutic agent to inhibit the growth and metasta sis of accessory sex gland cancers, such as those derived from the prostate . (C) 1999 Published by Elsevier Science Ltd. All rights reserved.