Inhibition of azoxymethane-initiated colon tumor by bovine lactoferrin administration in F344 rats

13-Week oral repeated administration toxicity study of bovine lactoferrin in rats

Bovine lactoferrin (LF), which is an iron-binding glycoprotein in milk, was administered orally to groups of 12 males and 12 female rats at dose levels of 200, 600 and 2000mg/kg/day once daily for 13 weeks and its toxicity on repeated administration was examined. Throughout the administration period, there were no deaths caused by administration of the test compound, nor were there any adverse effects noted in the general condition of the animals. The study findings concerning body weight and food consumption, ophthalmology, urinalysis including water consumption, haematology, blood chemistry, necropsy, organ weights and histopathology revealed that there were no apparent changes due to administration of LF. Therefore, the level of LF at which no adverse effect was observed was considered to be 2000mg/kg/day for both sexes.

Chemopreventive effects of bovine lactoferrin on N-butyl-N-(4-hydroxybutyl)nitrosamine-induced rat bladder carcinogenesis

Chemopreventive effects of bovine lactoferrin (bLF), which is found at high concentrations in colostrum, on rat bladder carcinogenesis were investigated using a rat bladder medium-term bioassay. In experiment 1, a total of 80 F344 male rats, 6 weeks old, were divided into 5 groups. Groups 1 and 2 were treated with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in the drinking water for 8 weeks and after a 1-week interval, received dietary supplementation with 2% and 0.2% bLF, respectively. Group 3 received 0.05% BBN for 8 weeks and then no treatment. Group 4 was administered 2% bLF alone from week 9, without prior carcinogen exposure. Group 5 was maintained without any treatment throughout the experiment. All rats were killed at the end of week 36. Group 1 demonstrated a significantly decreased multiplicity of the bladder tumors (carcinomas and papillomas) as compared with group 3. Maximum cut surface areas of bladder tumors were also significantly decreased in groups 1 and 2 compared with group 3. No bladder tumors were observed in groups 4 or 5. In experiment 2, a total of 60 rats were divided into two groups (30 rats each); both were treated with 0.05% BBN for 4 weeks and after a 1-week interval, one received 2% bLF (group 1) and the other, basal diet (group 2) for 4 weeks. Group 1 demonstrated a tendency for decrease of the 5-bromo-2'-deoxyuridine (BrdU) labeling index. bLF was detected in the urine of rats fed bLF by ELISA as well as western blot analysis. The findings indicate that 2% bLF can inhibit BBN-induced rat bladder carcinogenesis, and that this may be due to bLF in the urine.

Milk and dairy products in cancer prevention: focus on bovine lactoferrin

Milk and dairy products constitute an important part of the western style diet. A large number of epidemiological studies have been conducted to determine effects of consumption on cancer development but the data are largely equivocal, presumably reflecting the different included components. It has been proposed that whereas fats in general could promote tumor development, individual milk fats like conjugated linoleic acid could exert inhibitory effects. There is also considerable evidence that calcium in milk products protects against colon cancer, while promoting in the prostate through suppression of circulating levels of 1,25-dihydroxyvitamin D3. Whey protein may also be beneficial, as shown by both animal and human studies, and experimental data have demonstrated that the major component bovine lactoferrin (bLF), inhibits colon carcinogenesis in the post-initiation stage in male F344 rats treated with azoxymethane (AOM) without any overt toxicity. The incidence of adenocarcinomas in the groups receiving 2% and 0.2% bLF were thus 15% and 25%, respectively, in contrast to the 57.5% control value (P<0.01 and P<0.05, respectively). Results in other animal models have provided further indications that bLF might find application as a natural ingredient of milk with potential for chemoprevention of colon and other cancers.

Chemopreventive effect of bovine lactoferrin on 4-nitroquinoline 1-oxide-induced tongue carcinogenesis in male F344 rats

The modifying effects of dietary feeding of bovine lactoferrin (bLF) on tongue carcinogenesis initiated with 4-nitroquinoline 1-oxide (4-NQO) were investigated in male F344 rats. The activities of phase II detoxifying enzymes, glutathione S-transferase (GST) and quinone reductase (QR), polyamine content and ornithine decarboxylase (ODC) activity in the tongue were also examined for mechanistic analysis of possible modifying effects of bLF on carcinogenesis. At 7 weeks of age, all animals except those treated with bLF alone and untreated rats were given 20 ppm 4-NQO in drinking water for 8 weeks to induce tongue neoplasms. Starting 7 days before 4-NQO exposure, experimental groups were fed experimental diets containing bLF (0.2% and 2%) for 10 weeks ("initiation feeding"). Starting 1 week after the cessation of exposure to 4-NQO, the other experimental groups given 4-NQO and a basal diet were fed the experimental diets for 22 weeks ("postinitiation feeding"). At week 32, the incidence and multiplicity of tongue neoplasms in the "initiation feeding" groups of 0.2% and 2% bLF and the "post-initiation feeding" group of 0.2% bLF were lower than those of the 4-NQO alone group, but without statistical significance. However, "post-initiation feeding" of 2% bLF caused a significant reduction in the incidence (20% vs. 55%, P=0.02418) and multiplicity (0.25+/-0.54 vs. 0.70+/-0.71, P<0.05) of tongue squamous cell carcinoma (by 64%, P=0.02418). bLF treatment elevated liver and tongue GST activities and liver QR activity. The "post-initiation feeding" with 2% bLF significantly decreased QR activity, proliferating cell nulcear antigen-positive index and ODC activity in the tongue. In addition, feeding with bLF decreased tongue polyamine content. These results suggest that bLF, when given at the 2% dose level during the post-initiation phase, exerts chemopreventive action against tongue tumorigenesis through modification of cell proliferation activity and/or the activities of detoxifying enzymes.

Characterization of antiviral activity of lactoferrin against hepatitis C virus infection in human cultured cells

We recently found that bovine lactoferrin (bLF), a milk glycoprotein belonging to the iron transporter family, prevented hepatitis C virus (HCV) infection in human hepatocyte PH5CH8 cells, that are susceptible to HCV infection, and demonstrated that the anti-HCV activity of bLF was due to the interaction of bLF and HCV. In this study we further characterized the anti-HCV activity of bLF and the mechanism by which bLF prevents HCV infection. We found that bLF inhibited viral entry to the cells by interacting directly with HCV immediately after mixing of bLF and HCV inoculum. The anti-HCV activity of bLF was lost by heating at 65 degrees C, and other milk proteins (mucin, beta-lactoglobulin and casein) did not prevent HCV infection, indicating that bLF prevented HCV infection in a rather specific manner. Furthermore, we found that bovine lactoferricin, a basic N-terminal loop of bLF that is an important region for antibacterial activity, did not exhibit any anti-HCV activity, suggesting that some other region is involved in anti-HCV activity. We confirmed that prevention of HCV infection by bLF was a general phenomenon, because bLF inhibited HCV infection with all five inocula examined, and bLF inhibited HCV infection in human MT-2C T-cells, that were susceptible to HCV infection. In addition, infection with hepatitis G virus, which is distantly related to HCV, was prevented also by bLF. In conclusion, lactoferrin is a natural glycoprotein which effectively protects against HCV infection in hepatocytes and lymphocytes by neutralizing the virus.

Prevention of colon carcinogenesis and carcinoma metastasis by orally administered bovine lactoferrin in animals

Bovine lactoferrin (bLF), a milk protein known to have bacteriostatic properties was examined for its preventive effects on colon and other organ carcinogenesis and experimental metastasis. (Experiment 1) The influence on colon carcinogenesis was investigated in male rats treated with azoxymethane (AOM), then received 2 or 0.2% bLF for 36 weeks. Significant reduction in the incidence (27% and 46% of the control, respectively) and number of adenocarcinomas of the large intestine was observed. (Experiment 2) In BALB/c mice bearing subcutaneous (s.c.) implants of colon carcinoma 26 (Co 26Lu). bLF demonstrated significant inhibition of spontaneous lung metastasis (approximately 43% of the control). Number of cytotoxic asialoGM1+ and CD8+ cells in white blood cells increased (171% and 122% of control, respectively) after treatment. Results of those experiments indicate that bLF remarkably prevents colon carcinogenesis and lung metastasis of colon carcinoma cells, possibly due to increasing cytotoxic cells in the peripheral blood.

Lactoferrin inhibits hepatitis C virus viremia in patients with chronic hepatitis C: a pilot study

Hepatitis C virus (HCV) is associated with the development of cirrhosis and hepatocellular carcinoma. We recently found that bovine lactoferrin, a milk protein belonging to the iron transporter family, effectively prevented HCV infection in cultured human hepatocytes (PH5CH8). We tested the hypothesis that lactoferrin inhibits HCV viremia in patients with chronic hepatitis C. Eleven patients with chronic hepatitis C received an 8-week course of bovine lactoferrin (1.8 or 3.6 g/day). At the end of lactoferrin treatment, a decrease in serum alanine transaminase and HCV RNA concentrations was apparent in 3 (75%) of 4 patients with low pretreatment serum concentrations of HCV RNA. However, 7 patients with high pretreatment concentrations showed no significant changes in these indices. This pilot study suggests that lactoferrin is one potential candidate as an anti-HCV reagent that may be effective for the treatment of patients with chronic hepatitis.

Possible chemopreventive effects of bovine lactoferrin on esophagus and lung carcinogenesis in the rat

A milk component, bovine lactoferrin (bLF), previously shown by us to be a strong chemopreventive of colon carcinoma development, was examined for its influence on other organs using a rat multi-organ carcinogenesis model. Male F344 rats, aged 6 weeks, were treated sequentially with diethylnitrosamine (DEN, i.p.), dihydroxy-di-N-propylnitrosamine (DHPN, in drinking water) and N-nitrosomethylbenzylamine (NMBA, s.c.) during the first 8 weeks (DDN treatment), and then bLF was administered in the basal diet, at a dose of 2, 0.2, 0.02 or 0.002%. Other groups were given DDN treatment or bLF alone as controls. All surviving animals were killed at week 41, and major organs were examined histopathologically for neoplastic lesions. In the esophagus, a tendency for reduction in development of papillomas was evident in the bLF-treated animals, along with a significant suppression of relatively large-sized papillomas (more than 50 mm3 volume) at the 0.2% dose (P<0.05, 11% of the control). The multiplicity of tumors (adenomas and carcinomas) in the lung was also decreased in animals fed 0.02% bLF (1.98+/-0.41 per cm2 lung tissue section, P<0.05) compared to the control group (3.48+/-0.33). No enhancing or inhibitory effects of bLF on tumor development in other organs were noted. The present results indicate that bLF exerts chemopreventive effects in the esophagus and lung in addition to the colon.

Inhibitory effects of bovine lactoferrin on colon carcinoma 26 lung metastasis in mice

In order to determine the effects of the multifunctional iron-binding glycoprotein, lactoferrin (LF), and related compounds on tumor growth and metastasis, bovine LF (bLF), and bLF hydrolysate and lactoferricin (bLFcin), active products generated by acid-pepsin hydrolysis were administered orally to BALB/c mice bearing subcutaneous (s.c.) implants of the highly metastatic colon carcinoma 26 (Co 26Lu). bLF and the bLF hydrolysate demonstrated significant inhibition of lung metastatic colony formation from s.c. implanted tumors without appreciable effects on tumor growth. bLFcin displayed a tendency for inhibition of lung metastasis. On the other hand, bLF did not exert marked anti-metastatic activity in athymic nude mice bearing Co 26Lu, though bLF had a tendency to inhibit the lung metastatic colony formation associated with anti-asialoGM1 antibody (Ab) treatment. AsialoGM1+ and CD8+ cells in white blood cells were increased after treatment with bLF. In vitro, the viability of Co 26Lu-F55 cells was markedly decreased when co-cultured with white blood cells from mice administrated bLF p.o., but recovered on treatment with anti-asialoGM1 Ab or anti-CD8 mAb and complement. The results suggest bLF and related compounds might find application as tools in the control of metastasis and that asialoGM1+ and CD8+ cells in the blood are important for their inhibitory effects.

Influence of lactoferrin feeding and injection against systemic staphylococcal infections in mice

Human and bovine lactoferrins (Lfs) and bovine lactoferrin hydrolysate (LH) were assessed in vitro and in vivo for their antibacterial effects on Staphylococcus aureus. Lactoferrins showed weak in vitro antibacterial activity while Fe-saturated Lfs and LH showed no activity. Lactoferrin-treated mice (1 mg, i.v.) when injected i.v. with 10(6) staphylococci, showed 30-50% reduction in kidney infections, and viable bacterial counts in the kidneys decreased 5-12-fold. The inhibitory effect was dose-dependent up to 1 mg Lf. Lactoferrins were effective when given 1 day prior to the bacterial challenge, after which there was no significant effect even at doses up to 5 mg. Apo- and Fe-saturated forms of human and bovine Lfs were all equally effective, while LH was not protective. Human and bovine Lfs with different degrees of iron saturation (9-97%) were found to be equipotent. Feeding mice with 2% bLf in drinking water also reduced the kidney infections by 40-60%, and viable bacterial counts, 5-12-fold. The results suggest a potential for the use of Lfs as natural antibacterial proteins for preventing bacterial infections.

Inhibitory effects of bovine lactoferrin on intestinal polyposis in the Apc(Min) mouse

Chemopreventive effects of bovine lactoferrin (bLF), previously shown to strongly inhibit intestinal carcinogenesis in rats (K. Sekine, E. Watanabe, J. Nakamura, N. Takasuka, D.J. Kim, M. Asamoto, V. Krutovskikh, T.H. Baba, T. Ota, M.A. Moore, M. Masuda, H. Sugimoto, H. Nishino, T. Kakizoe, H. Tsuda, Inhibition of azoxymethane-initiated colon tumor by bovine lactoferrin administration in F344 rats, Jpn. J. Cancer Res. 88 (1997) 523-526; K. Sekine, Y. Ushida, T. Kuhara, M. Iigo, H. Baba-Toriyama, M.A. Moore, M. Murakoshi, Y. Satomi, H. Nishino, T. Kakizoe, H. Tsuda, Inhibition of initiation and early stage development of aberrant crypt foci and enhanced natural killer activity in male rats administered bovine lactoferrin concomitantly with azoxymethane, Cancer Lett. 121 (1997) 211-216), on spontaneous intestinal polyp development were assessed in the ApcMin mouse, a model for both familial adenomatous polyposis and sporadic colon cancers. In the experiment, 54 mice at 6 weeks of age were given 2% bLF (15 mice), 0.2% bLF (15 mice) and AIN-93G (24 mice) as basal diet ad libitum for 8 weeks. An overall tendency for a reduction in the total number of polyps in the small intestine was evident in the bLF-treated animals, along with significant suppression in the jejunum at the 2% dose (P < 0.05, 68% of the control). In addition, body growth suppression, presumed to be due to anemia and/or intussusception as a consequence of numerous polyps in the intestine, was alleviated. No toxic effects were observed in the intestinal epithelium. Although not as obvious as observed for the rat case, the data suggest that bLF may be a chemopreventor of intestinal polyposis.

The survival of ingested lactoferrin in the gastrointestinal tract of adult mice

Lactoferrin is an 80 kDa major protein component of mammalian colostral whey. The antimicrobial active centre of lactoferrin, lactoferricin (Lfcin), may also be an important determinant of the interaction between lactoferrin and specific receptors on lymphocytes. We have documented the survival in vivo of ingested lactoferrin in the gastrointestinal tract of adult mice by surface-enhanced laser desorption/ionization affinity MS. Various kinds of degraded lactoferrin fragments were detected as molecular-ion peaks corresponding to Lfcin after being captured by an affinity capture device, hydrolysis in situ and laser desorption/ionization. No evident molecular-ion peaks of Lfcin were observed upon analysis of faeces from mice fed commercial milk, whereas lactoferrin fragments containing the Lfcin region were detected at concentrations in the order of at least pmol/g in the faeces of mice fed milk enriched with lactoferrin at 40 mg/ml. These results suggest that ingested lactoferrin would survive transit through the gastrointestinal tract as partially degraded forms containing the receptor-binding region(s) as well as the antimicrobial active centre.

Lactoferrin markedly inhibits hepatitis C virus infection in cultured human hepatocytes

We found that bovine lactoferrin (bLF), a milk protein belonging to the iron transporter family, effectively prevented hepatitis C virus (HCV) infection in cultured human hepatocytes (PH5CH8), a cell line susceptible to HCV infection and supportive of HCV replication. Because preincubation of HCV with bLF was required to prevent the infection of HCV to the cells, and preincubation of bLF with the cells showed no inhibitory effect on HCV infection, we demonstrated that the anti-HCV activity of bLF was due to the interaction of bLF with HCV, but not due to the interaction of bLF with the cells. We further found that human lactoferrin also had anti-HCV activity, but bovine transferrin, the other member of the iron transporter family, did not have anti-HCV activity. Our findings suggest that lactoferrin is one of candidates for an anti-HCV reagent that will be well-tolerated and effective in the treatment of patients with chronic hepatitis.

Inhibition of initiation and early stage development of aberrant crypt foci and enhanced natural killer activity in male rats administered bovine lactoferrin concomitantly with azoxymethane

The influence of concomitant administration of bovine lactoferrin (bLF) on induction of aberrant crypt foci (ACF) by azoxymethane was investigated in male F344 rats. Two percent bLF and 3% Bifidobacterium longum (B. longum), as a positive control, significantly decreased the numbers of ACF as well as the total numbers of aberrant crypts reproducibly in three independent studies (2% bLF, P < 0.01; 3% B. longum, P < 0.05). Most importantly large size foci composed of four or more crypts were always significantly decreased by 2% bLF (P < 0.05). Additional investigation of the natural killer activity of spleen cells demonstrated enhancement by bLF (P < 0.01) and B. longum (P < 0.01) in line with the levels of influence on foci induction, indicating a possible role for elevated immune cytotoxicity in the observed inhibition.