Down-regulation of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx)-induced CYP1A2 expression is associated with bovine lactoferrin inhibition of MeIQx-induced liver and colon carcinogenesis in rats

Iron-saturated bovine lactoferrin: a promising chemopreventive agent for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a tumor with minimal chance of cure due to underlying liver diseases, late diagnosis, and inefficient treatments. Thus, HCC treatment warrants the development of additional strategies. Lactoferrin (Lf) is a mammalian multifunctional iron-binding glycoprotein of the innate immune response and can be found as either a native low iron form (native-Lf) or a high iron form (holo-Lf). Bovine Lf (bLf), which shares many functions with human Lf (hLf), is safe for humans and has several anticancer activities, including chemotherapy boost in cancer. We found endogenous hLf is downregulated in HCC tumors compared with normal liver, and decreased hLf levels in HCC tumors are associated with shorter survival of HCC patients. However, the chemoprotective effect of 100% iron saturated holo-bLf on experimental hepatocarcinogenesis has not yet been determined. We aimed to evaluate the chemopreventive effects of holo-bLf in different HCC models. Remarkably, a single dose (200 mg kg-1) of holo-bLf was effective in preventing early carcinogenic events in a diethylnitrosamine induced HCC in vivo model, such as necrosis, ROS production, and the surge of facultative liver stem cells, and eventually, holo-bLf reduced the number of preneoplastic lesions. For an established HCC model, holo-bLf treatment significantly reduced HepG2 tumor burden in xenotransplanted mice. Finally, holo-bLf in combination with sorafenib, the advanced HCC first-line treatment, synergistically decreased HepG2 viability by arresting cells in the G0/G1 phase of the cell cycle. Our findings provide the first evidence suggesting that holo-bLf has the potential to prevent HCC or to be used in combination with treatments for established HCC.

Unlocking the potential of milk whey protein components in colorectal cancer prevention and therapy

Extensive research from large prospective cohort studies and meta-analytical investigations over recent decades have consistently indicated that dairy foods have protective effects, reducing the risk of colorectal cancer. Most of the literature has explored the potential role of milk minerals and vitamins in managing colorectal cancer. Yet, there is a paucity of a comprehensive summary of the anticancer attributes of milk protein components and their underlying mechanisms of action. Recent advancements have spotlighted the potential of whey proteins, including β-lactoglobulin, α-lactalbumin, serum albumin, and lactoferrin, as promising candidates for both the prevention and treatment of colorectal cancer. Notably, whey proteins have demonstrated a more pronounced capacity for suppressing carcinogen-induced tumors when compared to casein. Their strong binding affinity enables them to serve as effective carriers for small molecules or drugs targeting colon cancer therapy. Furthermore, numerous studies have underscored the anti-inflammatory and antioxidant prowess of whey proteins in cancer prevention. Additionally, whey proteins have been shown to trigger apoptosis, hinder tumor cell proliferation, and impede metastasis. This comprehensive review, therefore, not only substantiates the significance of incorporating whey protein components into a balanced daily diet but also underscores their potential in safeguarding against the onset and progression of colorectal cancer.

Lactoferrin: A Nutraceutical with Activity against Colorectal Cancer

Homeostasis in the human body results from the tight regulation of several events, since too little inflammation disrupts the process of tissue repair and remodeling, whereas too much exerts a collateral effect by causing tissue damage with life-threatening consequences. In some clinical conditions, such as inflammatory bowel disease (IBD), inflammation functions as a double-edged sword by either enabling or inhibiting cancer development and progression. Generally, cancer develops through evasion mechanisms that regulate cell growth, causing a high rate of uncontrolled proliferation, and mechanisms for evading cell death, such as apoptosis. Moreover, chronic inflammation is a factor that contributes to colorectal cancer (CRC), as observed in individuals with IBD; all these conditions favor an increased rate of angiogenesis and eventual metastasis. Lactoferrin (Lf) is a mammalian iron-binding multifunctional glycoprotein regarded as a natural compound that up- and downregulates both humoral and cellular components of immunity involved in regulating the inflammatory response and maintaining gut homeostasis. Human and bovine Lf share high sequence homology and have very similar antimicrobial, anti-inflammatory, and immunomodulatory activities. Bovine Lf from milk is considered a safe molecule and is commercially available in large quantities. This review mainly focuses on the regulatory effects of orally administered bovine Lf on the inflammatory response associated with CRC; this approach indicates that CRC is one of the most frequently diagnosed cancers and affects the intestinal tract with high clinical and epidemiologic relevance. Thus, this review may provide foundations for the potential use of bovine Lf alone or as a natural adjunct agent to increase the effectiveness and reduce the side effects of anticancer chemotherapy.

Interaction of Lactoferrin with Unsaturated Fatty Acids: In Vitro and In Vivo Study of Human Lactoferrin/Oleic Acid Complex Cytotoxicity

As shown recently, oleic acid (OA) in complex with lactoferrin (LF) causes the death of cancer cells, but no mechanism(s) of that toxicity have been disclosed. In this study, constitutive parameters of the antitumor effect of LF/OA complex were explored. Complex LF/OA was prepared by titrating recombinant human LF with OA. Spectral analysis was used to assess possible structural changes of LF within its complex with OA. Structural features of apo-LF did not change within the complex LF:OA = 1:8, which was toxic for hepatoma 22a cells. Cytotoxicity of the complex LF:OA = 1:8 was tested in cultured hepatoma 22a cells and in fresh erythrocytes. Its anticancer activity was tested in mice carrying hepatoma 22a. In mice injected daily with LF-8OA, the same tumor grew significantly slower. In 20% of animals, the tumors completely resolved. LF alone was less efficient, i.e., the tumor growth index was 0.14 for LF-8OA and 0.63 for LF as compared with 1.0 in the control animals. The results of testing from 48 days after the tumor inoculation showed that the survival rate among LF-8OA-treated animals was 70%, contrary to 0% rate in the control group and among the LF-treated mice. Our data allow us to regard the complex of LF and OA as a promising tool for cancer treatment.

Different iron-handling in inflamed small and large cholangiocytes and in small and large-duct type intrahepatic cholangiocarcinoma

Cholangiocarcinoma (CCA) represents the second most common primary hepatic malignancy and originates from the neoplastic transformation of the biliary cells. The intrahepatic subtype includes two morpho-molecular forms: large-duct type intrahepatic CCA (iCCA) and small-duct type iCCA. Iron is fundamental for the cellular processes, contributing in tumor development and progression. The aim of this study was to evaluate iron uptake, storage, and efflux proteins in both lipopolysaccharide-inflamed small and large cholangiocytes as well as in different iCCA subtypes. Our results show that, despite an increase in interleukin-6 production by both small and large cholangiocytes, ferroportin (Fpn) was decreased only in small cholangiocytes, whereas transferrin receptor-1 (TfR1) and ferritin (Ftn) did not show any change. Differently from in vitro models, Fpn expression was increased in malignant cholangiocytes of small-duct type iCCA in comparison to large-duct type iCCA and peritumoral tissues. TfR1, Ftn and hepcidin were enhanced, even if at different extent, in both malignant cholangiocytes in comparison to the surrounding samples. Lactoferrin was higher in large-duct type iCCA in respect to small-duct type iCCA and peritumoral tissues. These findings show a different iron handling by inflamed small and large cholangiocytes, and small and large-duct type iCCA. The difference in iron homeostasis by the iCCA subtypes may have implications for the tumor management.

Effects of oral bovine lactoferrin on a mouse model of inflammation associated colon cancer

Patients with ulcerative colitis or colonic Crohn's disease have a significantly increased risk of developing colorectal cancer. Bovine lactoferrin (bLF) reportedly inhibited the development of colon cancer in rats and mice, and in a placebo controlled trial, ingestion of bLF inhibited the growth of intestinal polyps. In addition, in a case study, a patient with Crohn's disease was reported to have remained in remission for over 7 years while ingesting 1 g of bLF daily. Thus, bLF has an inhibitory effect on colon carcinogenesis, and it may also promote remission of Crohn's disease. The purpose of this study was to investigate the effects of bLF in a mouse model of colorectal cancer related to irritable bowel disease (IBD). The mice were divided into 4 groups: (i) no treatment; (ii) treated with bLF only; (iii) treated with azoxymethane plus dextran sulfate sodium (AOM + DSS); and (iv) treated with AOM + DSS + bLF. AOM was used to initiate intestinal cancer, and DSS was used to induce IBD-like inflammation in the intestine of the C57BL/6 mice. At the end of the study, the mice treated with AOM + DSS + bLF had a better fecal score, fewer lesions in the colon, and less weight loss than the mice treated with AOM + DSS without bLF. However, there were no statistically significant differences between the two groups with respect to tumor burden.

Regulation of PKB/Akt-pathway in the chemopreventive effect of lactoferrin against diethylnitrosamine-induced hepatocarcinogenesis in rats

BACKGROUND

Abnormal activation of protein kinase B (PKB) is associated with many cancers. This makes inhibition of PKB signaling pathway a promising strategy for cancer therapy. Lactoferrin (Lf) has been reported for its inhibition of tumor growth and metastasis, however, the mechanism is not completely understood. Its anti-hepatocarcinogenic activity has not taken the deserved recognition despite the additional advantages of Lf as an antiviral against hepatitis C virus, the main cause of hepatocellular carcinoma (HCC), and as a targeting ligand for delivering chemotherapeutics to hepatoma cells.

METHODS

This study evaluated the anti-hepatocarcinogenic effect of Lf, and the role of PKB in this effect using diethylnitrosamine (DENA)-induced HCC rat model, and a primary cell culture prepared from the induced hepatic lesions (DENA-HCC cell culture).

RESULTS

Up-regulation of activated PKB in the hepatocytes of rats with DENA-induced HCC was observed, as measured biochemically in the liver homogenate, and localized immunohistochemically. This was accompanied by increment of hepatocytes proliferation, and expression of vascular endothelial growth factor and endothelial nitric oxide synthase. Involvement of PKB in DENA-induced HCC was confirmed by the observed decrease in cell proliferation in DENA-HCC cell culture that was treated with PKB inhibitor. In Lf-treated rats, a dose-dependent chemopreventive effect was observed, with decreased expression and activation of PKB, amelioration of the other DENA-induced alterations, and stimulation of apoptosis. In vitro, Lf blocked PKB activator-induced cell proliferation.

CONCLUSION

These findings support the chemopreventive activity of Lf against HCC, and suggest regulation of PKB-pathway as a potential mechanism underlying this effect.

Plant-based biopharming of recombinant human lactoferrin

Recombinant proteins are currently recognized as pharmaceuticals, enzymes, food constituents, nutritional additives, antibodies and other valuable products for industry, healthcare, research, and everyday life. Lactoferrin (Lf), one of the promising human milk proteins, occupies the expanding biotechnological food market niche due to its important versatile properties. Lf shows antiviral, antimicrobial, antiprotozoal and antioxidant activities, modulates cell growth rate, binds glycosaminoglycans and lipopolysaccharides, and also inputs into the innate/specific immune responses. Development of highly efficient human recombinant Lf expression systems employing yeasts, filamentous fungi and undoubtedly higher plants as bioreactors for the large-scale Lf production is a biotechnological challenge. This review highlights the advantages and disadvantages of the existing non-animal Lf expression systems from the standpoint of protein yield and its biological activity. Special emphasis is put on the benefits of monocot plant system for Lf expression and the biosafety aspects of the transgenic Lf-expressing plants.

An investigation of growth factors and lactoferrin in naturally occurring ovine pulmonary adenomatosis

Ovine pulmonary adenomatosis (OPA), also known as jaagsiekte, is a transmissible beta retrovirus-induced lung tumour of sheep that has several features resembling human bronchoalveolar carcinoma (BAC). Angiogenesis has been suggested to be one of the most important factors underlying tumour growth and invasion. This process involves the action of growth factors including vascular endothelial growth factor (VEGF)-C, basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF)-C and its receptor (PDGFR-α). Bovine lactoferrin (bLF), an iron and heparin-binding glycoprotein secreted into various biological fluids, has been implicated in innate immunity and has anti-inflammatory and anti-tumour functions. Tissues from 16 cases of OPA were compared with tissues from seven healthy control sheep by immunohistochemistry. Expression of the markers was assessed semi-quantitatively by ascribing an immunoreactivity score (IRS) with a maximum value of 300. VEGF-C, bFGF, PDGF-C, PDGFR-α and bLF signals were detected in 10/16, 15/16, 12/16, 15/16 and 10/16 of the OPA cases studied, respectively. bLF expression was weak in the neoplastic epithelial cells (IRS 21.4 ± 10.0) in contrast to high levels detected in infiltrating macrophages and plasma cells (IRS 141.3 ± 24.8 and 140.0 ± 25.1, respectively). The PDGFR-α IRS was elevated for neoplastic epithelial cells (108.9 ± 18.2) and was lowest for macrophages and plasma cells (20.4 ± 13.1 and 13.7 ± 12.4, respectively). These results suggest that bFGF, VEGF-C and PDGF-C have roles in the pathogenesis of OPA. bLF may activate macrophages and plasma cells in these lesions, but limited expression of bLF by neoplastic cells may be a consequence of defective or impaired function of this molecule.

Tumorigenesis of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), but not enhancing effects of concomitant high-fat diet, on lung carcinogenesis in female A/J mice

It has been reported that 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) induces liver tumors and to a lesser extent lung lesions, lymphomas and leukemias in CDF(1) mice. Since a number of case control studies have pointed to a positive association between fat consumption and lung cancer, we examined the lung carcinogenic potential of MeIQx treatment concomitant with a high-fat diet using female A/J mice. Groups 1 and 2 were fed a diet supplemented with MeIQx at a concentration of 600 ppm. Groups 1 and 3 received a diet containing 20% corn oil and group 4 was fed the basal diet alone. After 1 week, 10 mice in each group were sacrificed for measurement of cytochrome P450 (CYP)1A2 mRNA in the liver and lung. The remaining mice were maintained on their respective diets until termination, 32 weeks after the initial MeIQx treatment, when lung proliferative lesions were analyzed. The incidences and multiplicities of hyperplasias and adenomas in MeIQx-treated groups (groups 1 and 2) were significantly higher than in the groups without MeIQx treatment, with a significant increase in the incidences and multiplicities of adenomas + carcinomas, as well as hyperplasia + adenomas + carcinomas (lung proliferative lesions). Lung carcinomas were observed in 1 mouse in each of the MeIQx-treated groups. However, the high-fat diet (groups 1 and 3) did not affect the incidences or multiplicities of lung proliferative lesions. Expression levels of CYP1A2 mRNA after MeIQx treatment significantly increased >3-fold in livers, but no significant change was noted in the lungs, where levels were very low at 1/210 and 1/923 the values for livers. In conclusion, following a 32-week period, we confirmed the lung tumorigenic potential of MeIQx which possibly occurs due to proximate carcinogens activated by CYP1A2 in the liver. However, we failed to detect any influence of a high-fat diet.

Lactoferrin and cancer disease prevention

Lactoferrin (LF) is an iron-binding glycoprotein that is composed of the transferrin family and is predominantly found in the products of the exocrine glands located in the gateways of the digestive, respiratory, and reproductive systems, suggesting a role in the non-specific defence against invading pathogens. Additionally, several physiological roles have been attributed to LF, namely regulation of iron homeostasis, host defence against infection and inflammation, regulation of cellular growth, and differentiation and protection against cancer development and metastasis. These findings have suggested LF's great potential therapeutic use in cancer disease prevention and/or treatment, namely as a chemopreventive agent. This review looks at the recent advances in understanding the mechanisms underlying the multifunctional roles of LF and future perspectives on its potential therapeutic applications.

Modulation of xenobiotic-metabolizing enzymes and redox status during chemoprevention of hamster buccal carcinogenesis by bovine lactoferrin

OBJECTIVE

Chemoprevention by dietary constituents has emerged as a novel approach to control oral cancer incidence. We therefore evaluated the chemopreventive efficacy of bovine milk lactoferrin (bLF) on 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis.

METHODS

Hamsters were divided into four groups. The right buccal pouches of animals in groups 1 and 2 were painted with 0.5% DMBA three times a week for 14 wk. Animals in group 2, received in addition, basal diet containing 0.2% bLF. Group 3 animals were given 0.2% bLF alone. Group 4 animals served as control. The status of carcinogen-metabolizing enzymes, the extent of lipid peroxidation and glutathione-dependent antioxidants in the buccal pouch and liver as well as bone marrow micronuclei incidence were used as biomarkers.

RESULTS

All the hamsters painted with DMBA alone for 14 wk, developed HBP carcinomas that showed diminished lipid peroxidation and increased activities of carcinogen-metabolizing enzymes and antioxidants with enhanced bone marrow micronuclei. In the liver of tumor bearing animals, the increase in phase I enzymes and lipid peroxidation was accompanied by reduced activities of antioxidant and phase II detoxification enzymes. Administration of bLF decreased the incidence of DMBA-induced micronuclei and HBP carcinomas by decreasing phase I enzymes, modulating lipid peroxidation and enhancing antioxidant and phase II enzyme activities.

CONCLUSION

The chemopreventive effects of bLF is mediated by reducing DMBA-induced genotoxicity and modulating carcinogen-metabolizing enzymes and oxidant-antioxidant profile in the target organ as well as in the liver.

Nitric oxide as a target of complementary and alternative medicines to prevent and treat inflammation and cancer

Nitric oxide (NO) and associated reactive nitrogen species (RNS) are involved in many physiological functions. There has been an ongoing debate to whether RNS can inhibit or perpetuate chronic inflammation and associated carcinogenesis. Although the final outcome depends on the genetic make-up of its target, the surrounding microenvironment, the activity and localization of nitric oxide synthase (NOS) isoforms, and overall levels of NO/RNS, evidence is accumulating that in general, RNS drive inflammation and cancers associated with inflammation. To this end, many complementary and alternative medicines (CAMs) that work in chemoprevention associated with chronic inflammation, are inhibitors of excessive NO observed in inflammatory conditions. Here, we review recent literature outlining a role of NO/RNS in chronic inflammation and cancer, and point toward NO as one of several targets for the success of CAMs in treating chronic inflammation and cancer associated with this inflammation.

Prevention of carcinogenesis and cancer metastasis by bovine lactoferrin

Increasing attention is being paid to chemopreventive agents for individuals at high risk of cancer. We have concentrated on bovine lactoferrin (bLF), an 80 kDa iron-binding glycoprotein known to have anti-microbial and immunoprotective effects. Lactoferrin is particularly abundant in colostrum, and is also present in tears, saliva and seminal and uterine secretions. However, only little is known regarding its influence on carcinogenesis. We have shown preventive effects of bLF and its fragment peptide, lactoferricin (bLFcin), consisting of a 25 amino acid sequence without iron binding capacity, on chemically-induced colon carcinogenesis in the rat and transplanted carcinoma cell metastasis in the mouse. The mechanisms are wide-spectrum, including elevation of caspase-1 and IL-18 in the small intestine, enhancement of the cell killing activity of cytotoxic T and natural killer (NK) cells, and anti-inflammatory and anti-angiogenic effects. It also inhibits the induction of liver CYP1A2, a carcinogen activating enzyme, and induces apoptosis in the colon epithelium of carcinogen treated rats. Thus, bLF possesses multi-functional potential to suppress carcinogenesis and is a good candidate for practical application in humans.

Post-initiation chemopreventive effects of dietary bovine lactoferrin on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis in female A/J mice

We investigated the effects of bovine LF (bLF) on different phases of NNK-induced lung tumorigenesis in A/J mice. Mice were orally administered 0.02, 0.2 and 2% bLF during the initiation phase, and 2% bLF during the whole tumorigenesis phase or post-initiation phase. Administered bLF during the post-initiation phase showed significant reduction of macroscopical lung nodules, and immunohistochemically decreased expression levels of cell proliferation marker and increased expression levels of apoptosis marker in lung proliferative lesions. bLF might inhibit NNK-induced mouse lung tumorigenesis, only when given limited to the post-initiation phase, through modification of cell proliferation and/or apoptosis.

Enhancement by acrylamide of N-methyl-N-nitrosourea-induced rat mammary tumor development—possible application for a model to detect co-modifiers of carcinogenesis

Acrylamide (AA) has recently been reported to be spontaneously formed in fried and baked foods with various concentrations. Although carcinogenicity in humans is as yet equivocal, numerous positive genotoxicity data in vitro and in vivo and results of rat long-term carcinogenicity studies demonstrating tumor induction at multiple sites, like the mammary gland, thyroid and testes, suggest the risk with dietary exposure may not be negligible. In the present study, to establish a medium-term carcinogenesis model for screening of agents with the potential to modify AA effects on the mammary gland and thyroid, we pretreated rats with 7,12-dimethylbenz(a)anthracene (DMBA), in combination with N-bis(2-hydroxypropyl)nitrosamine (DHPN), or N-methyl-N-nitrosourea (MNU) alone and then administered AA at 20 and 40 ppm in the drinking water for 30 weeks. The incidence and multiplicity of mammary tumors were increased at the high dose (P<0.05) in MNU- but not DMBA+DHPN-treated rats. No thyroid tumors were induced in any case. The results indicate that the MNU model is suitable for detection of modifiers of AA actions.

Cancer prevention by natural compounds

Increasing attention is being paid to the possibility of applying cancer chemopreventive agents for individuals at high risk of neoplastic development. For this purpose by natural compounds have practical advantages with regard to availability, suitability for oral application, regulatory approval and mechanisms of action. Candidate substances such as phytochemicals present in foods and their derivatives have been identified by a combination of epidemiological and experimental studies. Plant constituents include vitamin derivatives, phenolic and flavonoid agents, organic sulfur compounds, isothiocyanates, curcumins, fatty acids and d-limonene. Examples of compounds from animals are unsaturated fatty acids and lactoferrin. Recent studies have indicated that mechanisms underlying chemopreventive potential may be combinations of anti-oxidant, anti-inflammatory, immune-enhancing, and anti-hormone effects, with modification of drug-metabolizing enzymes, influence on the cell cycle and cell differentiation, induction of apoptosis and suppression of proliferation and angiogenesis playing roles in the initiation and secondary modification stages of neoplastic development. Accordingly, natural agents are advantageous for application to humans because of their combined mild mechanism. Here we review naturally occurring compounds useful for cancer chemprevention based on in vivo studies with reference to their structures, sources and mechanisms of action.

Induction of DNA-adducts and increase of 8-hydroxy-2-deoxyguanosine, but no development of preneoplastic lesions in offspring liver with transplacental and trans-breast milk exposure to 2-amino-3,8-dimethylimidazo [4,5-f ]quinoxaline (MeIQx) in rats

Humans may be exposed to 2-amino-3,8-dimethylimidazo[4,5-f ]quinoxaline (MeIQx) at low doses during the period of gestation and lactation, and thereafter throughout life. The current study was designed to examine the possibility that early exposure may increase the risk of liver tumor development and related genetic changes. Male and female F344 rats were therefore administered MeIQx in diet (1, 10 and 100 ppm) for 4 weeks before mating and also during gestation and lactation. We also examined the carcinogenic risk of low-dose maternal and post-weaning exposure (MeIQx at doses of 1 and 10 ppm). Surviving male F1 rats were sacrificed under ether anesthesia at 19 weeks of age for analyses of glutathione S-transferase placental form-positive foci in the liver and aberrant crypt foci in the colon, as putative preneoplastic lesions. Transplacental and trans-breast milk exposure to MeIQx did not enhance development of the lesions, and levels of cell proliferation in the liver also did not differ from control values. However, excretion of MeIQx into breast milk and transfer to the fetus and offspring were observed with resultant hepatic MeIQx-DNA adducts and 8-hydroxy-2'-deoxyguanosine formation. Thus, our data suggest that maternal exposure to MeIQx during the period of pregnancy and lactation may not increase the risk of hepatocarcinogenesis in male offspring, despite causing genetic damage. If this result can be extrapolated to humans, exposure to MeIQx may not increase carcinogenic risk in offspring at usual human exposure levels.

Lactoferrin modifies apoptosis-related gene expression in the colon of the azoxymethane-treated rat

Lactoferrin, an iron-binding glycoprotein, exhibits suppressive effects on development of azoxymethane (AOM)-induced tumors in the rat colon, but the mechanisms are largely unknown. In this study, we investigated the effect of lactoferrin on the gene expression of 10 apoptosis-related molecules in colon mucosa of AOM-treated rats during early and late stages of colon carcinogenesis by reverse transcription PCR. Here we document that a death-inducing receptor, Fas, and a pro-apoptotic Bcl-2 family member, Bid, are increased in the colon mucosa in proportion to decreases in AOM-induced aberrant crypt foci by lactoferrin. Similarly, increased expression of the pro-apoptotic Bcl-2 family member, Bax, was also observed in AOM-induced tumors in rats fed by lactoferrin. These results indicate that Fas and pro-apoptotic Bcl-2 members participate in the lactoferrin action and may contribute to suppressive effects on tumor development in the rat colon.