In experimental studies, bovine
lactoferrin (bLF) has been found to significantly inhibit colon, esophagus, lung, and bladder
carcinogenesis in rats when administered orally in the post-initiation stage. Furthermore, concomitant administration with
carcinogens resulted in inhibition of colon
carcinogenesis, possibly by suppression of phase I
enzymes, such as
cytochrome P450 1A2 (
CYP1A2), which is preferentially induced by carcinogenic heterocyclic
amines. Enhancement of the activities of their phase II counterparts, such as
glutathione S-transferase might have also played a critical role in post-initiation suppression in a study of tongue
carcinogenesis. Anti-metastatic effects were moreover detected when bLF was given intragastrically to mice bearing highly metastatic colon
carcinoma 26 cells (Co 26Lu), with apparent enhancing influence on local and systemic immunity. Marked increase in the number of cytotoxic T and NK cells in the mucosal layer of the small intestine and peripheral blood cells was thus found, this in turn enhancing the production of
Interleukin 18 (IL-18) and caspase-1 in the epithelial cells of the small intestine, with possible consequent induction of
interferon (IFN)-gamma positive cells. Furthermore, bLF has been found to exert anti-hepatitis C virus (HCV) activity in a preliminary clinical trial in patients with
chronic active hepatitis due to this virus, a main causative factor in
hepatocellular carcinoma development in Japanese. More extensive clinical trials are now underway in the National
Cancer Center Hospital and other institutes to further explore the preventive potential against colon
carcinogenesis.